program one tuesday, may 23, 2000 ... - engg.ksu.edu

12000 Conference on Hazardous Waste Research

Program OneTuesday, May 23, 2000Bioremediation of PetroleumHydrocarbons

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THE ROLE OF THE VA-DOSE ZONE IN THENATURAL ATTENUA-TION OF GAS CONDEN-SATE HYDROCARBONS

1Kerry Sublette, 1Steve Harmon, 1Rick Yates,2Gary Trent, 3Ravi Kolhatkar, 4Greg Thoma,and 5Kathleen Duncan, 1Center for Environ-mental Research & Technology, University ofTulsa, 600 S. College Ave., Tulsa, OK 74104;2Environ Services, Tulsa, OK; 3Amoco Re-search Center, Naperville, IL; 4University ofArkansas, Fayetteville, AR; 5University ofOklahoma, Norman, OK;

1Phone:

(918) 631-3334, E-mail: [email protected].

Leaking underground concrete sumpsused to store produced water have contami-nated groundwater with gas condensatehydrocarbons at a gas production site near Ft.Lupton, Colorado. The source of contamina-tion has been removed; however, a plume ofhydrocarbon contamination extends some 46m from the original source location. This is anagricultural area and the water table is rathershallow (about 1.4 m on average) and fluctu-ates seasonally over 0.3 to 0.6 m. Further, thissite is in close proximity to a potential surfacereceptor, the South Platte River.

Amoco Production Co. and the Univer-sity of Tulsa have conducted extensive moni-toring of the groundwater at this site for over4 years in conjunction with microcosm studiesto ascertain the rate and extent of intrinsicbioremediation of hydrocarbons at the site.Goechemical indicators of biodegradation ofhydrocarbons by indigenous microorganismsinclude oxygen depletion, increased alkalinity,sulfate depletion, methane production, andFe+2 production associated with hydrocarboncontamination. Sulfate-reducing bacteria andmethanogens were also shown to be orders of

magnitude higher in contaminated sedimentscompared to noncontaminated areas. Lastly,metabolites of hydrocarbons degradation,including metabolites characteristic of anaero-bic degradation of xylenes and toluene, havebeen found in contaminated groundwater.

Clearly some purely anaerobic degrada-tion of toluene and xylenes occurs at the sitebased on the characteristic metabolites ofanaerobic degradation detected. However, therelative importance of this mechanism to theoverall attenuation of these or other BTEXcompounds is unknown. In addition the sitestill contains scattered free product floating onthe water table; therefore, there is also asignificant inventory of aliphatic hydrocarbonsat the site, which have not been shown todegrade under anaerobic conditions. Since theplume has been observed to be stable and thetotal hydrocarbon inventory seems to bedecreasing, some significant role for oxygen issuggested. Since this is a relatively shallowaquifer, the vadose zone may act as a signifi-cant source of oxygen for hydrocarbon degra-dation. In order to investigate the role of thevadose zone in the natural attenuation ofhydrocarbons at this site, an extensive charac-terization of the vadose zone has been carriedout as a function of depth. The vadose zonewas sampled in 15-cm increments from thesurface to the water table in both contaminatedand uncontaminated areas of the site. Each 15-cm sample was composited and analyzed forindividual C3+ hydrocarbons, hydrocarbonmetabolites, methane, CO

2, total organic

carbon (TOC), and total inorganic carbon(TIC). Methane, CO

2, TOC, and TIC were

also subjected to 13C analysis. Samples werealso analyzed to determine characteristics ofmicrobial populations using phospholipid fattyacid analysis (PLFA), degrading gradient gelelectrophoresis (DGGE), and gene probes forgenes related to aerobic biodegradation ofaliphatic and aromatic hydrocarbons. Resultsof these analyses and their implications withregard to the mechanisms of hydrocarbons’biodegradation in the vadose zone will bediscussed.

2 2000 Conference on Hazardous Waste Research

BIO-SEP: AN ADVANCEDBIOCATALYST SUPPORTSYSTEM FOR GROUND-WATER AND WASTE-WATER TREATMENT2

1Kerry Sublette, 1Steve Harmon, and 2CarlCamp,1Center for Environmental Research &Technology, University of Tulsa, 600 S. Col-lege Ave., Tulsa, OK 74014; 2Du Pont,Wilmington, DE; 1Phone: (918) 631-3085,1E-mail: [email protected].

Bio-Sep is a porous, adsorptive polymericbiocatalyst support that has numerous applica-tions in the treatment of groundwater andwastewater streams. Bio-Sep consists of 2-3mm spherical beads engineered from a com-posite of 25% polymer for toughness and highdurability and 75% powdered activated carbonfor high shock resistance. The bulk density ofthe beads is approximately 0.16 g/cm3 with aporosity of 75%. The median pore diameter is1.9 microns; however, large macropores (> 20microns) also exist inside the beads. Theseunique beads feature a structure that allowsmicroorganisms to colonize throughout theinternal volume of the bead, resulting in highbiomass density and high volumetric produc-tivity. Volumetric productivities of over 10times that of conventional activated sludgetreatment have been demonstrated. The Bio-Sep biocatalytic process has been demon-strated with a wide variety of contaminantsincluding hydrocarbons, methylene chloride,picric acid, ammonia, sulfidic caustic, pheno-lics, aldehydes and ketones, and amides. Thispaper will review the details of the Bio-Sepstructure and applications of this biocatalystsupport in environmental applications. Aspectsof Bio-Sep bioreactor design, as well aspotential bioprocessing applications, will alsobe reviewed.

Key words: Bio-Sep, biomass density, sludgetreatment

1Kerry Sublette, 1Lorrie Houston, 1SteveHarmon, 2Kathleen Duncan, and 3RaviKolhatkar, 1Center for Environmental Re-search & Technology, University of Tulsa, 600S. College Ave. Tulsa, OK 74104; 2Universityof Oklahoma, Norman, OK; 3BP Amoco,Naperville, IL.

An investigation of the impact of a hydro-carbon spill or leak on soil ecology or thepotential or progress of bioremediation ofcontaminated soil typically requires an enu-meration and characterization of microbialpopulations in the soil. Most conventionalmethods for enumeration require culturing ona solid medium (viable plate counts) or inliquid medium (most probable number counts).However, it has been estimated that 90% ofthe microorganisms in soil are non-culturable.Molecular microbial techniques which do notdepend on culturing give a more completepicture of the soil microbiology of an impactedsite. For example, phospholipid fatty acids(PFLA) from microbial cell membranes andcell walls may be extracted with an organicsolvent and characterized by GC/MS to yieldinformation about the total viable biomasspresent, community structure, metabolicstatus, and environmental stress. SpecificPLFA biomarkers can indicate the presenceand numbers of sulfate-reducing bacteria(SRB), methane-oxidizing bacteria, fungi,eucaryotes, etc. DNA extracted from soils canbe probed for specific genes such as thosespecific for aerobic degradation of aromatic oraliphatic hydrocarbons, ammonium oxidation,or sulfide reduction of SRB. Amplification of16s ribosomal DNA by PCR and separation ofthe products using degrading gradient gelelectrophoresis (DGGE) can allow determina-tion of the number and relative abundance ofeubacteria in soil samples. Subsequent se-quencing of individual bands from the gel can

USE OF MOLECULARTECHNIQUES TO INVES-TIGATE MICROBIALPOPULATIONS IN SOILIMPACTED BY HYDRO-CARBONS AND BRINE

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identify dominant organisms. Use of thesetechniques to characterize the microbialcommunity in soil impacted by crude oil will bediscussed.

MODELINGMULTI-SUBSTRATE BIO-DEGRADATION KINETICSOF BINARYPOLYCYCLIC AROMATICHYDROCARBON MIX-TURES

41Christopher Knightes and Catherine Peters,Department of Civil and EnvironmentalEngineering, Princeton University, Princeton,NJ 08544; 1Phone: (609) 258-1552, 1E-mail:[email protected].

Polycyclic aromatic hydrocarbons (PAHs)are an important class of environmental con-taminants because of their suspected carcino-genicity. Because they are organic compounds,PAHs represent a feasible source of carbon andenergy for naturally occurring microorganisms.Therefore, biodegradation is a feasibleremediation strategy for PAH-contaminatedsites. PAHs typically occur as complex mix-tures, but more research has focused on sole-substrate biodegradation. The goal of thisstudy was to investigate how multi-substrateMonod biodegradation kinetics can be used tomodel a binary mixture of PAHs and how thepresence of an additional substrate impacts thebiodegradation of the other substrate. Twoseries of experiments were performed, naph-thalene and 1-methylnaphthalene, and naphtha-lene and phenanthrene. The biodegradationstudies were performed as a series of indepen-dent batch aqueous experiments with twoPAHs available as substrates for a PAH-degrading consortium. Parallel abiotic reactorswere used to verify that abiotic losses wereminimal. The Monod kinetic parameters and

yield coefficients used to model the multi-substrate system were estimated from indepen-dent sole-substrate experiments. From theseexperiments, it is demonstrated that multi-substrate biodegradation kinetics can beadequately modeled using previously deter-mined sole-substrate parameterization. Fur-thermore, the multi-substrate model demon-strates two competing effects: enhancementand competitive inhibition. The compoundwith faster biodegradation kinetics (naphtha-lene) is not dramatically affected by the pres-ence of a secondary substrate. The slowerdegraded compounds (1-methylnaphthaleneand phenanthrene) have enhanced biodegrada-tion by the biomass growth on naphthalene,but not as enhanced as would be seen if therewere no competitive inhibition.

Key words: biodegradation, kinetics, multi-substrate, PAHs, mixtures

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ACCELERATEDBIOREMEDIATION OFPAH-CONTAMINATEDSOILS BY PRETREAT-MENT WITH FENTON’SREAGENT

1Kenneth Reardon and 2Shelley Allen, 1,2De-partment of Chemical and BioresourceEngineering, Colorado State University,Glover Room 100, Fort Collins, CO 80523;1Phone: (970) 491-6505, E-mail:[email protected]; 2Phone: (970)491-1123, E-mail:[email protected].

Chemical oxidation and bioremediationare two remediation techniques commonlyused to treat contaminated soil.Bioremediation can be an economically soundmethod of treating easily degradable com-pounds. However, many pollutants are noteffectively degraded by bioremediation.Chemical oxidation, on the contrary, success-fully degrades contaminants that are biologi-cally recalcitrant, but is considerably moreexpensive than the biological treatment. By

Program OneTuesday, May 23, 2000Bioremediation--PAHs


combining these two technologies, a cheaper,more effective method should result. For themost effective combination, the optimal extentof chemical oxidation must be found.

In a laboratory-scale project, soils ob-tained from two different sites were used tostudy the combination of chemical oxidationand bioremediation. The primary contaminantsin these soils were polycyclic aromatic hydro-carbons (PAHs) and pentachlorophenol (PCP),chosen because they are both recalcitrant andcarcinogenic. The specific chemical oxidationprocess utilized in this study involved theaddition of hydrogen peroxide along with aFenton’s-like reagent. This mixture was se-lected because it produces hydroxyl freeradicals, which have an oxidizing potentialsecond only to fluorine. In order to distributethe reagent properly into the soil, aMicroenfractionator™, designed by H&H EcoSystems, Inc., was used. TheMicroenfractionator is essentially an efficient,rapid, and large-scale mixing device. It notonly mixed the reagent homogeneously intothe soil, but also decreased the mass transferlimitations brought about by sorbed contami-nants. This decrease in mass transfer limita-tions increased the degradation rate by increas-ing the availability of the contaminants. Oncechemically oxidized and well mixed, the soilwas set aside to allow the indigenous microor-ganisms to biodegrade the remaining contami-nants. The effect of hydrogen peroxide wastested at three concentrations: zero, one, andtwo percent (by weight).

Soil samples were taken at regular inter-vals over a six-week period. These sampleswere analyzed for pollutant levels, microbialpopulation characteristics, and mutagenicity.The microbial population characteristicsstudied include total biomass, populationcomposition, and degradation activity.

The highest overall degradation wasachieved by the two-percent hydrogen perox-ide, which was the highest concentration ofhydrogen peroxide tested. This level of hydro-gen peroxide also had the largest impact on the

microbial community. The concentration ofmicroorganisms decreased by a factor of fourafter the hydrogen peroxide was added. How-ever, the microbial population reboundedwithin a week. The addition of even a smallamount of hydrogen peroxide produced betterdegradation than bioremediation alone.

Key words: bioremediation, oxidation, PAH,PCP, soil

1Eric Vestal, 2Angela Bielefeldt, 3KendraMorrison, 4Anuratha Ramaswami, 5TissaIllangasekare, 1Division of EnvironmentalScience and Engineering, Colorado School ofMines, Golden, CO 80401; 2Department ofCivil, Environmental, and ArchitecturalEngineering, University of Colorado, Boulder,CO 80309; 3U.S. EPA, 999-18th St., Suite 500,Denver, CO 80202; 4Department of CivilEngineering, University of Colorado (Den-ver), Denver, CO 80217; 5Amax Chair, Divi-sion of Environmental Science and Engineer-ing, Colorado School of Mines, Golden, CO80401; 1Phone: (303) 273-3483, 1E-mail:[email protected]; 2Phone: (303) 492-8433,2E-mail: [email protected];3Phone: (800) 227-8917, 3E-mail:[email protected]; 4Phone:(303) 556-4734, 4E-mail:[email protected]; 5Phone:(303) 384-2126, 5E-mail: tillanga@mines edu.

Nonaqueous-phase liquids (NAPLs)trapped in the subsurface as pools pose seriouslong-term groundwater contamination prob-lems. With traditional remediation methods,such as pump-and-treat, it is often impossibleto achieve complete removal of NAPL pools

ESTIMATION OF STY-RENE INHIBITION ANDINDUCTION KINETICPARAMETERS ON AMIXED CONSORTIUM OFPAH-DEGRADING BAC-TERIA: IMPLICATIONSFOR MODELING ANDDESIGNINGBIOISOLATIONSCHEMES

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and such methods can even promote unwanteddown-gradient migration (Cohen and Mercer,1993). The long-term, ubiquitous presence ofaromatic hydrocarbons in the environment hasallowed microorganisms in the subsurface todevelop the capability to metabolize them(Neff, 1979). Microbial metabolism of hydro-phobic organic contaminants typically found incoal tar, such as poly-aromatics (PAHs) andstyrene, makes bioremediation an attractive,low-cost cleanup strategy. Bioisolation pre-sents an in situ technology that can potentiallyretard mass transfer of the more solublecomponents as well as reduce overalldissolved-phased organic constituents incontaminant plumes, thereby effectively isolat-ing NAPL pools from downstream receptorlocations. The design of bioisolation/biostabilization schemes requires modeling ofnet mass transfer, degradation, transport, andbiogrowth. Microbial degradation kinetic rateconstants are critical to the accurate modelingof these phenomena. If substrate materialeither inhibits or inducts the microbial degra-dation, this can alter the accuracy of aMonod-type multicomponent, multi-electronacceptor kinetic expression used in the model-ing phase of remediation design engineering.We have found that styrene, in concentrationsgreater than 15 mg/L, is toxic (enzyme inhibi-tion) to a mixed consortium of PAH-degradingbacteria. There is also evidence that enzymaticinduction can affect the measured degradationkinetics, depending on the growth history ofthe culture. The kinetic data we present is for abacterial population of PAH degraders in thePsuedomonodaceae family that have beenmaintained in CSTRs and exposed to coal taras well as naphthalene, phenanthrene, and2-methylnaphthalene at aqueous solubilitylevels as well as styrene at 15 mg/L. Wepresent the experimental method used toidentify, measure, and uncouple the inductionand inhibition, the parameter estimation (inver-sion) process for quantifying the inhibitionconstant and induction curve within the frame-work of the multi-component, multi-electron

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acceptor Monod formulation, and the implica-tions for long-term bioisolation strategiesbased on semi-coupled mass transfer, degrada-tion, flow, transport, and biogrowth modeling.

Key words: biokinetics, bioisolation, model-ing, PAH, NAPL

1Syed Hasan, 2Suman Ghosh, and 2NamitaOswal, 1,2Department of Geosciences, Univer-sity of Missouri-Kansas City, 5100 RockhillRoad, Kansas City, MO 64110-2499; 1Phone:(816) 235-2976, E-mail: [email protected].

A partially bi-phasic, laboratory-scaleanaerobic digester was designed and utilizedfor optimum generation of methane, using ahigh strength landfill leachate with chemicaloxygen demand (COD) of 15,500 mg/L at aloading rate of 200 mL/day. The apparatuscomprises a downflow semi-continuous di-gester that was operated at mesophilic tem-perature (37 ± 0.5 °C) where the hydraulicretention time was maintained at 20 days.Modification to the conventional anaerobicdigestion was attempted by creating an aerobicphase two days prior to the effluent’s entryinto the anaerobic system. This modificationgave the digester sufficient buffering capacityto withstand limited environmental stress andprevented generation of excess acid that couldlead to a sour condition and resulting failure.Simultaneous monitoring of selected volatilefatty acids helped in optimizing the reactionconditions and maintaining stability of thedigester. Experimental results showed that thedigester could be used successfully to treat

Program OneTuesday, May 23, 2000Bioremediation--Applications

ANAEROBIC TREAT-MENT OF LANDFILLLEACHATE TO OPTIMIZEMETHANE GENERATION7


several different temperatures and hydraulicretention times (HRTs).

Results so far obtained suggestammonia-nitrogen removal and nitrification upto 65% in the first wetland. When compressedair aeration is not used, a stratified pattern ofammonia-nitrogen removal and nitrificationhas been observed, these being slightly fasterat the surface than at the bottom. This sug-gests that DO may be one of the limitingfactors for nitrogen removal in a constructedwetland. It seems that the limiting DO concen-tration is ca. 1 mg/l for nitrification to takeplace and hence, nitrogen removal. The tem-perature effect on COD and nitrogen removalhas been investigated by evaluating thefirst-order reaction rate constant and tempera-ture activity coeffficient (q). The ammonia andnitrate removal rates do not increase muchbeyond 18°C. Sulfur-limestone autotrophicdenitrification is very efficient (>95%), indicat-ing that the rate-limiting step for nitrogenremoval in the second wetland is nitrification.No SO

42- is detected in the effluent of the

second wetland, although it is detected imme-diately after the S/L section. In both reactors,NO

3--N removal increases with an increase of

HRT, while COD is removed very efficiently(up to 98%) at all HRTs. Currently, the effectof the ratios of COD/ammonium and COD/nitrate-N on nitrification and denitrification inthese wetlands are being investigated. Theresults of this study seem to indicate thatsubsurface constructed wetlands can be usedto treat wastewater generated by small com-munities.

Key words: constructed wetland, ammonia,nitrate, nitrification, denitrification, COD

1Achintya Bezbaruah, 2Tian Zhang, and 3JohnStansbury, 1,2,3Department of Civil Engineer-ing, 205 PKI, University of Nebraska-Lincolnat Omaha Campus, Omaha, NE 68182-0178;1Phone: (402) 554-3565, 1E-mail:[email protected]; 2Phone: (402) 554-3784, 2E-mail: [email protected];3Phone: (402) 554-3896, 3E-mail:[email protected].

As an alternative to conventional biologi-cal wastewater treatment systems, thelaboratory-scale subsurface constructed wet-land was used in this study for COD andnitrogen removal in a single reactor. Tworeactors, 11.5' x 0 5' x 3' each, have beenconstructed side by side, and located in acontrolled environment chamber. The reactorsare fed with primary settled municipal waste-water from a local treatment plant. The firstreactor is for COD removal, nitrification, andheterotrophic denitrification, while the secondone is for COD removal, nitrification, andsulfur/limestone (S/L) autotrophic denitrifica-tion. A polishing zone has been kept in bothreactors and they are equipped with aerationpipes for optional compressed air aeration.Plants are not grown in the reactors so as toexclude their effect in the process. The param-eters monitored are organic, ammonium, andhydraulic loading rates; and hydraulic retentiontimes (HRTs), COD, NH

4+-N, NO

3--N, DO,

pH, etc. The wetlands have been operated at

landfill leachate with high COD, and is capableof withstanding high loading rate and minorenvironmental shocks. The data showed a totalCOD removal of 79% and a methane yield of0.032 m3/kg of COD removal. Methane con-tent of the biogas varied between 35 and 39%.

Key words: bi-phasic anaerobic digester,landfill leachate, methane recovery

NITROGEN REMOVAL INLABORATORY-SCALECONSTRUCTED WET-LANDS8


trations below 100 mg/L. This inhibition wasbest described by the Monod kinetic equationwhere the effect of TNP10 inhibition is re-flected in the half-saturation constant (K

s). The

value of the Ks increased from between 1.4-

13.5 mg/L with no surfactant present to 13.6-202 mg/L at the highest level of inhibition. AtPCP concentrations above 200 mg/L, TNP10reduced the substrate inhibition effect of PCP,resulting in faster PCP degradation rates athigher concentrations of TNP10. Measure-ments of surfactant confirm that TNP10 is notdegraded by RA2. Calculations of a micellepartition coefficient (K

m) show that the differ-

ences in initial PCP degradation rates can beexplained by accounting for the amount ofPCP available to the cell in the aqueous solu-tion. A model is discussed based on theseresults where PCP is sequestered into micellesat high TNP10 concentrations to become lessavailable to the bacterial cell and resulting inobserved inhibition. Under substrate toxicityconditions, the same mechanism serves toincrease the rate of PCP biodegradation byreducing aqueous PCP concentrations to lesstoxic levels. TNP10 also enhanced the glucosedegradation and endogenous decay ratesbetween 500 and 5000 mg/L as measured bydissolved oxygen uptake and biomass growth.Tests of glucose degradation and endogenousdecay confirmed that TNP10 does not inhibitRA2 via a mechanism of general cellulartoxicity. These results suggest that TNP10 mayhave different effects on RA2, depending onthe nature of the substrate.

Key words: pentachlorophenol, surfactant,bioremediation, kinetics, inhibition

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MECHANISM AND KINET-ICS OF NONIONIC SUR-FACTANT INHIBITION OFPENTACHLOROPHENOLBIODEGRADATION

1Todd Cort and 2Angela Bielefeldt, 1,2Univer-sity of Colorado, Boulder, Department of CivilEnvironmental and Architectural Engineering,Campus Box 428, Boulder, CO 80309;1Phone: (303) 492-0139, 1E-mail:[email protected]; 2Phone: (303) 492-8433.

The use of surfactants has a great deal ofpotential to increase the biodegradation ratesof hydrophobic organic compounds in con-taminated environments by increasing the totalaqueous solubility of these compounds. How-ever, inhibitory effects of surfactants on thebiodegradation process have frequently beenreported. A variety of factors and mechanismshave been proposed to explain the inhibitionprocess, including cellular toxicity from inter-action of surfactant molecules with cell mem-branes (changing fluidity) or directly withmembrane-bound proteins, direct inhibition ofenzymes involved in the catabolic pathwayeither by association with the enzyme or withthe substrate, decreased bioavailability due tosequestration of the substrate compound intosurfactant micelles, or the accumulation oftoxic intermediates due to incomplete metabo-lism incurred from substrate-surfactant interac-tions. The future utility of surfactant-aidedbioremediation efforts relies on the ability toaccurately predict the effect of surfactants on agiven bacterial culture with a known set oforganic contaminants.

Several potential mechanisms of surfac-tant-induced inhibition of pentachlorophenol(PCP) biodegradation were tested using a purebacterial culture of Sphingomonaschlorophenolicum sp. Strain RA2. PCP andglucose degradation as well as endogenousdecay rates were measured in aqueous batchsystems in the presence of 10-5000 mg/L ofthe nonionic surfactant Tergitol NP-10(TNP10). Concentrations of TNP10 over 200mg/L inhibit biodegradation of PCP at concen-


from the primary and secondary digesters atthe City of Columbia Municipal WastewaterTreatment Plant, Missouri. These bacteriawere found to be very effective indehalogenating PCE. At the same time, thephenol-induced bacteria were added tocometabolize TCE. The microorganisms werecultured in a sequencing anoxic and aerobicbioreactor. A fast and complete PCEdehalogenation was achieved by proper con-trol of the nitrate-feeding concentration,substrate concentration, aeration, pH, andoxidation-reduction potential. A 24-hourcycle (22 hours for anoxic and 2 hours foraerobic) could completely reduce PCE with afeeding concentration of up to 100 µg/L. Inthe reactor, acetate, methanol, and phenolwere growth substrates and electron donors,and nitrate and PCE were elector acceptors.

Key words: tetrachloroethene (PCE),trichloroethene (TCE), anoxic/aerobic, fluid-

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TETRACHLOROETHENE(PCE) DEHALOGENATIONBY SEQUENCING AN-OXIC/AEROBICBIOREACTOR

Lei Wang and Robert Segar Jr., Departmentof Civil and Environmental Engineering,University of Missouri-Columbia, Columbia,MO 65211; Phone: (573) 882-0075; E-mail:[email protected].

As one of the important industrial sol-vents, tetrachloroethene (PCE) has beenwidely used worldwide Since PCE is difficultto treat by aerobic biological processes, mostresearch has been focused on anaerobicdehalogenation of PCE. A disadvantage of theanaerobic process is that the dechlorination isincomplete and the metabolites such as vinylchloride, a carcinogen chemical, can accumu-late in the reactor. To treat the less chlorinatedethenes, an aerobic process is necessary as thesecond stage. In this study, an anoxic/aerobicbiological process was employed to treat PCE.An oxygen-tolerant and denitrifying bacteriawas enriched from the mixed sludge taking

1J.G. Parsons, 1G. Gamez, 1K.J. Tiemann, and2J.L. Gardea-Torresdey, 1,2Department ofChemistry and Environmental Science andEngineering, University of Texas at El Paso,El Paso, TX 79968; 2Phone: (915) 747-5359,2E-mail: [email protected].

Due to current technologies used toextract gold from ores, increasing environmen-tal pollution has occurred. Existing technolo-gies for the extraction or recovery of goldinclude cyanidation which uses sodium cyanate(extremely toxic). Because of various acci-dents and wastes generated by the cyanidationprocess, an increasing need to develop newtechnologies to extract or recover gold fromaqueous solution has arisen. Previous experi-ments performed in this laboratory have shownthat alfalfa has the ability to reduce gold(III) togold(0). These experiments have also shownthat gold(III) at high concentrations isadsorbed by the alfalfa biomass independentlyof pH. pH profiles have been performed attrace levels for both native biomass and chemi-cally modified biomass using a 100 ppbgold(III) aqueous solution. However, at trace-level gold(III) concentrations, the adsorptionof gold(III) has been observed to be pHdependent. The observed trend in the bindingby the native alfalfa biomass was highest at pH3.0 (97%) and decreased (to approximately50%) at pH 4.0 and pH 5.0. However, theesterified biomass had an opposite binding

ized-bed bioreactor, denitrifier,dehalogenation

Program TwoTuesday, May 23, 2000Analytical Methods I

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DETERMINATION OFTRACE-LEVEL GOLD(III)BINDING TO ALFALFABIOMASS USING GFAASWITH ZEEMAN BACK-GROUND


trend, a low binding at pH 2.0 and 3.0 (50%)and a sharp increase in binding at pH 4.0 witha maximum binding at pH 5.0 (90%). Cur-rently, experiments are being performed to seethe effects of hard cations, such as calcium,magnesium, and sodium, on the binding ofgold(III) to the alfalfa biomass. Results will bepresented.

Key words: alfalfa, gold, Zeeman, GFAAS

1K.J. Tiemann, 1G. Gamez, 1J.G. Parsons, 1K.Dokken, 1I. Herrera, and 2J.L. Gardea-Torresdey, 1,2Department of Chemistry andEnvironmental Science and Engineering,University of Texas at El Paso, El Paso, TX79968; 2Phone: (915) 747-5359, 2E-mail:[email protected].

We have performed several studies todetermine the electrochemical properties ofCu(II) and Pb(II) binding by alfalfa biomassusing carbon paste alfalfa-modified electrodes.Experimental conditions such as alfalfa-carbonpaste concentrations, solution pH, and metalpreconcentration times were determined.Results of the electrochemical studies haveshown that an increase in response was ob-served by increasing the concentration ofalfalfa biomass with a maximum response at30% (w/w). In addition, the response wasfound to escalate as the pH of the Cu(II) andPb(II) solutions was raised from 2 to 6, whichparallels the trends observed from previouslyperformed batch experiments. X-ray absorp-tion spectroscopic studies were also performedto determine the actual chemical binding sitesthat are involved with Cu(II) and Pb(II)binding by the alfalfa biomass. Results fromthese studies will be presented.

Key words: XANES, EXAFS, alfalfa, biosen-sor, metal binding, copper, lead

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CAPILLARY ELECTRO-PHORESIS - INDUC-TIVELY COUPLEDPLASMA MASS SPEC-TROMETRY FOR NU-CLIDE DETERMINA-TIONS OF LANTHANIDESIN AN IRRADIATEDTANTALUM TARGETMATERIAL

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ELECTROCHEMICALAND X-RAY ABSORPTIONSPECTROSCOPIC STUD-IES OF CU(II) AND PB(II)BINDING TO ALFALFABIOMASS

1Jason Day, 1Joseph Caruso, 2J. SabineBecker, and 2H.J. Dietze, 1University ofCincinnati, Department of Chemistry, Cincin-nati, OH 45221-0172; 2Central Laboratoryfor Analytical Chemistry, Research CenterJülich, Jülich, 52425, Germany; 1Phone:(513) 556-9304, 1E-mail:[email protected].

A nuclide analysis lanthanide elementswas performed using capillary electrophoresis(CE) interfaced to a double-focusing sectorfield, inductively coupled plasma mass spec-trometer (DF-ICP-MS). Peak areas were usedto calculate isotope ratios and lanthanide oxideformation data. Isotope ratio determinationsof samples with natural isotope ratios showgood agreement with natural isotope values.Detection limits were in the low ng ml-1 con-centration range for the most abundant iso-topes. This procedure was applied to a samplefrom a tantalum target material which had beenirradiated with a high-energy proton beam for500 days. Spallation nuclides in these sampleswere lanthanides in the concentration range of~1 µg ml-1 to low ng ml-1. Additionally, spalla-tion-product nuclide abundances are signifi-cantly different from natural isotope ratios.The CE separation method has the advantageof short analysis times and very small sampleamounts (~35 nl).

Key words: lanthanide oxide formation,isotope ratios, CE separation method


Furfural background information, chemi-cal properties, and current analytical methodsare reviewed. A description is given of theinvestigative procedures that were used tounderstand the source of the difficulties and todevelop a better method. The developedanalytical method is described and compared

to previously used methods.

Key words: furfural, analysis

C.A. Ponce de Leon and Joseph Caruso,University of Cincinnati, Department ofChemistry, Mail Location 0172, Cincinnati,OH 45221-0172; 1Phone: (513) 556-9304;1E-mail: [email protected].

Selenium is an important micronutrientfor living organisms. Selenium is especiallyimportant because it is capable of being substi-tuted for sulfur in amino acids. Seleniumspecies are of special interest because of theiranti-cancer properties, as shown by Clark etal., but selenium in high concentrations and incertain forms may be toxic. The naturalabundance of selenium in nature is low; there-fore, selenium enriched foods are produced.The microorganisms present in certain foodstransform the selenium into different seleniumspecies; thus, different foods contain differentspecies. These selenium-enriched foods havebeen analyzed to elucidate the selenium speciespresent. Techniques such as ion-exchangechromatography, ion-pair chromatography,reversed-phase chromatography as well as gaschromatography have been used for thispurpose. These techniques have helped eluci-date the selenoamino acids present in thesamples, but the chiral properties of theorganoselenium species have yet to be studied.This is of importance since in living organisms,only one of the enantiomers has activity.Chiral chromatography can separate thedifferent enantiomers in a compound. Chiral-HPLC chromatography can be coupled withICP-MS to give a very selective and sensitivetechnique.

This work will present the chiral analysisof selenoamino acids that may be present inselenium-enriched yeast. The yeast analysed

Program TwoTuesday, May 23, 2000Analytical Methods II

1John Huntington, Ph.D. and 2Phillip Stark,P.E., 1Analytica Environmental Laboratories,Incorporated, 325 Interlocken Parkway, Suite200, Broomfield, CO 80021; 2EnviroGroupLimited, 7208 South Tucson Way, Suite 125,Englewood, CO 80112; 1Phone: (303) 469-8868, ext. 166, 1E-mail:[email protected]; 2Phone: (303)790-1040, 2E-mail:[email protected].

Furfural is a substance that is found inorganic vegetative matter and many foods.Furfural is produced from biomass and is usedas a solvent in numerous manufacturing pro-cesses. It is a listed hazardous waste. Analysisof the compound is complicated by a tendencyto undergo oxidation, hydrolysis, and polymer-ization in the sample as well as laboratorystandards.

Groundwater was analyzed for the pres-ence of furfural due to an accidental industrialrelease. Initial analytical results gave extremelypoor spike recoveries, poor precision, andpoor accuracy. EnviroGroup Limited re-quested the assistance of Analytica Environ-mental Laboratories, Incorporated in develop-ing a procedure for sample collection andsample analysis which would give more consis-tent and usable data.

14

PROCEDURE FOR OB-TAINING REPRODUC-IBLE FURFURAL ANA-LYTICAL RESULTS

15

DETECTION OFSELENOAMINO ACIDSENANTIOMERS IN SELE-NIUM-ENRICHED YEASTUSING HPLC COUPLEDTO ICP-MS


was enriched by two different procedures. Theseparation was carried out using a crown etherstationary phase. Also, the results obtainedusing different extraction methods will bepresented.

I have developed a technique for deter-mining toxicity of all sorts of compounds.More than 200 chemicals have been assayed. Ihave compared results with my assay withresults from 22 other assays and find I getcomparable results. The method uses thebacterium Rhizobium meliloti, the bacteriumthat grows symbiotically with alfalfa and fixesnitrogen for the plant. The bacterium canreduce a thiazole tetrazolium dye, MTT, veryreadily and toxic chemicals inhibit the reduc-tion of the dye. Large amounts of toxin inhibitthe reduction severely; smaller amounts have alesser effect so the test is quantitative. Aspectrophotometer is used to estimate reduc-tion of the dye. Divalent cations inhibit reduc-tion of the dye. This can be eliminated by theaddition of small amounts of EDTA.

The test is simple. High school studentshave contributed to the research. The test isinexpensive; the bacteria can be grown foralmost nothing and the chemicals used areinexpensive and are readily available. The testis rapid; it takes less than an hour to carry outthe reactions, plot the results, and calculate thetoxicity of the sample. Any laboratory able togrow bacteria should be able to carry out theassay readily. We have compared this test with22 other tests.

We have also compared these 22 testswith one another. Tests involving animals

tested in vitro simply are not as sensitive astests using fish, Daphnia magna, or microor-ganisms. This work will be discussed in detail.

Key words: toxicity, compounds, Rhizobiummeliloti

ENVIRONMENTAL AP-PLICATIONS OF CHIRALHPLC

1Wen-yee Lee and 2James Salvador, 1,2Depart-ment of Chemistry, University of Texas at ElPaso, El Paso, TX 79968; 1Phone: (915) 747-5849, 1E-mail:[email protected]; 2Phone:(915) 747-5704, 2E-mail:[email protected].

Chiral pesticides are asymmetric and thushave a non-superposible mirror image orenantiomer. Most of the chiral pesticides arecurrently sold, used, and analyzed in enanti-omer pairs as if they were just one singlecompound even though enantiomers havedifferent biological activities and thus differentenvironmental ramifications.

In our study, commercial chiral HighPerformance Liquid Chromatography (HPLC)was used to separate and quantify chiralpesticides. The separation of six locally usedracemic pesticides will be reported. Thedegradation of these chiral pesticides in soilsamples will also be presented.

Key words: pesticides, chiral, enantiomer

17

Program TwoTuesday, May 23, 2000Analytical Methods III/Biosorption

James Botsford, Department of Biology, NewMexico State University, Las Cruces, NM88003; Phone: (505) 646-3726, E-mail:[email protected].

16

A SIMPLE, INEXPENSIVEAND RAPID METHOD TODETERMINE TOXICITYUSINGA BACTERIAL INDICA-TOR ORGANISM


Polyethyleneimine. The positively chargedcellulosesulphatederivate/microalgae solutionprecipitated immediately. A thin membranesurrounds the resulting hollow spheres. Afteradditional treatment, the encapsulatedmicroalgae posses good mechanical andchemical properties for using them as a newbiosorbent in an adsorption column.

After optimizing the particle-size electronmicroscope, pictures of the biosorbents weretaken to locate the heavy metals and examinethe structure of the hollow spheres, e.g. thethickness of the membrane and the pore sizeinside the particles.

Kinetic experiments were carried out todetermine the mass transport resistance as afundamental requirement for the mathematicaldescription and the scaleup of the process.

The metal uptake of the biosorbent andthe matrix system was quantitatively evaluatedusing the heavy metals lead, cadmium, nickel,and zinc. The experimental results are in agood correspondence with the Langmuir-isotherm-model.

Batch experiments were made to deter-mine the selectivity of heavy metal uptake.Depending on the encapsulated microalgae andcellulosederivate, the selectivity in heavy metaluptake is changing.

Experiments in an adsorption columnwere made with synthetic and real wastewater,caused by the accumulator industry, contami-nated with lead and zinc. The results showthat the biosorbent is suitable for using it in anadsorption column.

The desorption of the adsorbed heavymetals is established by a reduction of the pHvalue. Therefore, a reversible loading/unload-ing of the adsorbed heavy metal, using HCI orcitric acid for the desorption process, is pos-sible.

Key words: microalgae, heavy metals, immo-bilization, biosorption

18

REMOVAL OF HEAVYMETAL IONS FROMWASTE WATER BY AD-SORPTION ON IMMOBI-LIZED MICROALGAE

A. Wilke, G. Bunke, and R. Buchholz, TUBerlin, Inst. of Biotechnology, Dept.Bioprocess Engineering, AckerstraBe 71-76,13355 Berlin, Germany; Phone: ++49 (0) 30314-72527, Fax: ++49 (0) 30 314-72573, E-mail: [email protected].

The contamination of wastewater and soilwith toxic heavy metal ions is a complexproblem. The removal of this contaminationhas received much attention in recent years.From an environmental protection point ofview, heavy metal ions should be removed atthe source in order to avoid pollution ofnatural waters and subsequent metal accumula-tion in the food chain. Conventional methodsfor removal are chemical precipitation, chemi-cal oxidation, chemical reduction, ion ex-change, filtration, electrochemical treatmentand evaporation. All these procedures havesignificant disadvantages, which are for in-stance incomplete removal, high-energyrequirements, and production of toxic sludgeor waste products that also require disposal.These methods often are very expensive.Alternative methods for heavy metal removalwere developed in the last decade. One ofthem is the biosorption of heavy metal ions onbiomass. Microalgae are known to have highcapacities and selectivities in the uptake ofheavy metals. Although the biosorption pro-cess has many advantages compared to con-ventional techniques, there are only a fewestablished processes up to now. The use ofscreened microalgae to reduce the heavy metalconcentration in wastewater effluents is themain subject.

A new biosorbent material, based ondifferent microalgae with high metal capacitiesor selectivities, was obtained by a new immo-bilization process. For this procedure,cellulosesulphatederivates were mixed withfreeze-dried microalgae. The resulting mixturewas dropped in a solution containing


according to the Langmuir Adsorption Model.With respect to the selectivity of thebiosorption, C. salina and L. taylorii showed apreference for the uptake of lead over cad-mium, nickel, and zinc in a four-metal solutionat the same molar concentration. In a three-metal system of cadmium, nickel, and zinc withL. taylorii, zinc was bound preferentially overcadmium and nickel. The capacity for nickelwas the lowest. The optimum pH of sorptionfor L. taylorli was observed between pH 3 andpH 7. All metals can be quantitatively des-orbed at pH 1, e.g. with 0.1 M hydrochloricacid. L. taylorii has been used successfully in atechnical process for the purification of waste-water in the cooperation project (Wilke et al.,this conference).

The cell wall of an alga consists of avariety of polysaccharides, some of whichcontain anionic carboxyl, sulphate, or phos-phate groups. These are considered as bindingsites of the metals. The surface of algae werecharacterized by elemental analysis and esteri-fication of carboxyl groups and spectroscopicmethods including FT-IR, scanning electronmicroscopy, and X-ray microanalysis. Esterifi-cation of carboxyl groups present in the cellwalls resulted in a decrease in metal binding.These findings suggest that carboxyl groupsare important in metal ion adsorption to thesematerials. Scanning electron microscopy incombination with X-ray microanalysis con-firmed that the binding sites for the four metalsare on the surface of the algae. X-ray mi-croanalysis of the surface of L. taylorii alsodemonstrated the presence of high calciumcontent. Further sorption experiments on L.taylorii showed that the calcium is displacedby the metals during biosorption similar to anion exchange process.

Capacity and selectivity of the binding ofmetals were studied by introduction of addi-tional functional groups into the cell wallpolysaccharides. Phosphorylation of L. tayloriihas been the most successful method at themoment. The phosphate content of the algaecould be increased from 0.6 mmol to 4.4

19

CHEMICAL CHARAC-TERIZATION OF THEBIOSORPTION OF HEAVYMETALS

1Dipl.-Leb.-Chem. S. Klimmek and2Prof. Dr. rer. nat. H.-J. Stan, 1,2TechnicalUniversity Berlin, Institute of Food Chemistry,Gustav-Meyer-Allee 25, D-13355 Berlin,Germany; 1Phone: ++49-30314727782, 1E-mail: [email protected]; 2Phone:++49-30314727702, 2E-mail: [email protected].

The ability of microorganisms to enrichheavy metals from aqueous solution has beenknown for some decades. The enrichment ofthe metals occurs actively only with living cells(bioaccumulation) or passively at the surfaceof both living and dead cells (biosorption). Thebiosorption is a fast and reversible reaction ofthe heavy metals with the microorganism’sbiomass and is therefore of particular eco-nomic interest.

A project of the cooperative researchprogram Sfb 193 financed by German Re-search Society, which deals with the biologicaltreatment of industrial and commercial wastewater, is to investigate the biosorption of theindustrially relevant heavy metals lead, cad-mium, nickel, and zinc by algae. The resultsare taken as basis for an application-orientedmethod for the purification of wastewater asdeveloped by Wilke, Bunke, and Buchholz, TUBerlin.

Twenty-five algae species were investi-gated for their ability to bind the four metals ina screening method. Quantitative evaluation ofthe screening results identified the most suit-able algae for this application. Chlorella salina(Chlorophyceae) and Lyngbya taylorii (Cyano-phyceae) proved to be the most efficient algaeunder investigation. Further characterization ofthe biosorption was carried out on the twomost efficient species. The sorption isothermsof the four metals by L. taylorii showed, forexample, maximum capacities of 1.4 mmollead, 0.44 mmol cadmium, 0.65 mmol nickel,and 0.59 mmol zinc per gram of dry biomass


time, and temperature dependent. In order toresolve the mechanism of both binding andreduction of gold(III) by alfalfa biomass,further experiments were performed. Theeffect of chemical modification of the alfalfabiomass on gold(III) binding and reductionwas determined. Also, further X-ray absorp-tion near edge structure (XANES) and ex-tended X-ray absorption fine structure(EXAFS) spectroscopy studies were per-formed to assess the oxidation state andnearest neighbor of the bound gold as a func-tion of time. The results indicate that gold(III)goes to gold(I) and then to gold(0). Also,EXAFS shows that binding may occur via anitrogen or oxygen ligand. Results of theseexperiments will be presented.

Key words: XANES, EXAFS, alfalfa, gold,phytofiltration, metal binding, chemicalmodification

1Brian Barbaris, 2Eric Betterton, 3RobertArnold, 3Wendell Ela, 3Laura Berry, 3DanielSamorano, 3Karen Kerr, and 3Xiumin Ju,1,2Department of Atmospheric Sciences, TheUniversity of Arizona, Tucson, AZ 85721;1Phone: (520) 621-6832, 1E-mail:[email protected]; 3Department ofChemical and Environmental Engineering,The University of Arizona, Tucson, AZ 85721;3Phone: (520) 621-6044.

Perchloroethene (PCE) was scrubbedfrom contaminated landfill soil vapor by

mmol phosphorus per gram biomass. Themodified L. taylorii shows very goodbiosorption properties. L. taylorii showedmaximum capacities of 3.22 mmol lead, 2.52mmol cadmium, 2.91 mmol nickel, and 2.70mmol zinc per gram of dry biomass. Thedesorption of the metals from phosphorylatedbiomass is in turn more difficult in comparisonwith the untreated L. taylorii. Tests showedthat the metals can be desorbed with 3 Mhydrochloric acid.Biosorption by algae thus demonstrated itselfto be an useful alternative to conventionalsystems for the removal of toxic metals fromwastewater.

Key words: biosorption, algae, cadmium,lead, nickel, zinc

1G. Gamez, 1K. Dokken, 1I. Herrera, 1J.G.Parsons, 1K.J. Tiemann, 2M.J. Yacaman, and3J.L. Gardea-Torresdey, 1,3Department ofChemistry and Environmental Sciences,University of Texas at El Paso, El Paso, TX79968; 2Instituto National de InvestigacionesNucleares, Mexico; 3Phone: (915) 747-5359,3E-mail: [email protected].

Current precious metal recovery tech-nologies that use harsh chemicals may repre-sent a threat to the environment and publichealth. Thus, there is a necessity to developenvironmentally friendly systems to retrieveprecious metals. In previous experiments, deadalfalfa biomass has shown to be efficient forgold(III) recovery. Gold(III) binding to alfalfabiomass is rapid, pH independent, and in-creases with time and temperature. Further-more, with X-ray absorption spectroscopy,alfalfa was found to reduce gold(III) togold(0) and produces nanoparticles. Transmis-sion electron micrographs showed

nanoparticles of several shapes and sizes. Thereduction process was also found to be pH,

Program ThreeTuesday, May 23, 2000Air Emissions Management

MECHANISMS OF AU(III)BINDING ANDBIOREDUCTION BY AL-FALFA BIOMASS20

21

PHOTO-TREATMENT OFPERCHLOROETHENE INSOIL VAPOR AT THEHARRISON ROAD LAND-FILL, TUCSON, ARIZONA


continuous mode, both the scrubber and thephotoreactor were operated simultaneously forextended periods of time. The effectiveness ofthe photoreactor was determined by compar-ing liquid-phase concentrations of PCE andother targets in the reactor influent and efflu-ent. PCE concentrations are lowered by 90percent or more in a matter of hours. Resultsalso indicate that the reaction is inhibited byoxygen in the soil vapor (currently 10 percentdue to the injection of air by city contractors).However, we were able to eliminate (photore-duce) interfering oxygen and also the PCE byincreasing the number of photoreactor tubes.

We are in the process of identifyingreaction intermediates detected by gas chroma-tography and also the final products of reac-tion. From the limited data to date, it isevident that scrubber design for any reasonabledegree of contaminant transfer is feasiblesimply by increasing the gas/liquid contacttime. The rate of photolysis could probably beincreased by a factor of ten simply by addingparabolic reflectors to the system, therebyboosting treatment times to twelve minutes orless.

Key words: reductive dehalogenation, soilvapor, perchloroethene

contact with a 2-propanol/acetone solution(9:1 v/v) and then destroyed by exposure tosunlight in a photoreactor. The treatmentsystem (scrubber and photoreactor) wasdeployed at the Harrison Road Landfill wheresoil vapor is being extracted and treated by thecity of Tucson using a conventional granulatedcarbon absorption system. The 120-acrelandfill is now closed and capped, but soilvapor containing 100-200 mg/L PCE (andother chlorinated organics) was readily ob-tained by diverting a small flow of soil vaporto the experimental treatment system. Exhaustgases were returned to the city’s system aheadof the carbon absorption units.

In the experimental system, contaminatedsoil vapor is pumped at a rate of 1L/min. intothe bottom of a 60 cm x 5 cm countercurrentcolumn packed with ½”ceramic Berl saddles.PCE was stripped by dissolution in the 2-propanol/acetone mixture that flowed down-ward through the scrubber. Field data indicatethat the scrubbing efficiency was approxi-mately 90 percent. A number of other haloge-nated compounds, probably including TCE,Freon-11, and Freon-12, were also detected inthe solvent.

The 2-propanol/acetone solvent, contain-ing the scrubbed PCE, was pumped to thephotoreactor, a series of four 1.2-m quartz orglass tubes (2.5cm diameter), where the PCEwas destroyed by solar-promoted photolysis(Betterton et al., Environ. Sci. Technol.,accepted Jan. 2000). The photoreactor wasdesigned for a theoretical detention time ofone hour at a solvent flow rate of 50 mL/min.and a PCE destruction efficiency of >90percent. The “spent” isopropanol/acetonesolvent was then returned to the scrubber toclose the loop.

Two types of field experiments have beenconducted to date. In the first quasi-batchmode, the solvent was preloaded with PCEthroughout the night and then exposed tosunlight while being recirculated in thephotoreactor during the day (without furthercontact with the sol vapor). In the second,


22

EVALUATION OF COM-BUSTION PROCESSESFOR PRODUCTION OFFEEDSTOCK CHEMI-CALS FROM AMMO-NIUM SULFATE ANDAMMONIUM BISULFATE

oxidized in a two-stage combustor to yield aNO

X free SO

2 stream. Two-stage combustion

was achieved by installing a restrictor in thechamber, thus creating two stages. Thecombustor volume between the burner and therestrictor (the first stage) was maintainedunder reductive conditions and secondary airwas added directly above the restrictor tocreate an oxidative atmosphere for the secondstage. To enhance the versatility of the pro-cess catalytic conversion of H

2S and COS to

methyl mercaptan, (CH3SH) is being evalu-

ated.

Key words: ammonium sulfate, ammoniumbisulfate, combustion

1Kevin Brown and 2R.E. Babcock, 1SinclairOil Corporation, Salt Lake City, UT; 2Univer-sity of Arkansas, 3202 Bell EngineeringCenter, Fayetteville, AR 72701; Phone: (501)575-4951, E-mail: [email protected].

In May 1999, EPA published its proposalto reduce emissions from light-duty vehiclesand light-duty trucks. The proposal, known as“Tier 2 Proposal,” is to be phased in beginning2004 and would also significantly reducesulfur content in gasoline. Sulfur in gasolinereduces the effectiveness of a vehicle’s emis-sion control system.

The proposed sulfur levels in gasolinewould require refiners to meet an average of30 ppm by 2004, down from the currentaverage of more than 300 ppm. The maximumamount of sulfur in gasoline for purposes ofaveraging would be capped at 80 ppm after athree-year phase-in. Small refiners would havean additional four years to comply.

EPA has designed its proposal in anattempt to provide flexibility for both the autoindustry and the oil industry. One such flex-ibility allows for a market-based credit tradingand banking system for both industries to

1Yvonne Liske, 1Shubhen Kapila, 2VirgilFlanigan, 3Paul Nam, and 4Steve Lorbert,1Department of Chemistry, University ofMissouri, Rolla, MO 65409; 2Department ofMechanical Engineering, University ofMissouri, Rolla, MO 65409; 3Center forEnvironmental Science and Technology,University of Missouri, Rolla, MO 65409;4Novus InternationaL St. Louis. MO; 1Phone:(563) 341-6187, 1E-mail: [email protected];2Phone: (573) 341-6606, 2E-mail:[email protected]; 3Phone: (573) 341-6162,3E-mail: [email protected]; 4E-mail:[email protected].

Several million tons of these chemicalsare produced as by-products during a numberof commercially important chemical manufac-turing processes. At present, a large portionof these salts are disposed in deep wells atconsiderable cost to the chemical industry.These costs can be reduced or eliminatedthrough the development of resource recoverytechnologies. Combustion-based technologieshold considerable potential in this area. Thecombustion of ammonium bisulfate and ammo-nium sulfate solutions was studied undervarious atmospheres in a combustion chamberdesigned in-house to recover the sulfur value.It was determined that varied sulfur species,such as sulfur dioxide (SO

2), hydrogen sulfide

(H2S), and carbonyl sulfide (COS) can be

obtained quantitatively by manipulating thecombustion stoichiometry in a single or two-stage burner configuration. Under near sto-ichiometric conditions, >95% of the sulfurvalue was recovered as SO

2. However, traces

(230 - 350 ppm) of nitrogen oxides were alsoobtained under these conditions. The reducedsulfur species H

2S and COS accounted for

>95% of the total sulfur during sub-stoichio-metric combustion. These species were readily

23

IMPLICATIONS OF RE-DUCED SULFUR LEVELSIN FUELS


reward those who lead the way in reducingpollution. This paper discusses various pro-cess options available to refiners and theexpected impact of each option.

1Angela Bielefeldt, 2Tissa Illangasekare, and1Rosanna LaPlante, 1University of Colorado,Campus Box 428, Boulder, CO 80309; 2Colo-rado School of Mines, Dept. Env. Science &Engrg., Golden, CO 80401-1887; 1Phone:(303) 492-8433, 1Fax: (303) 492-6644;2Phone: (303) 384-2126.

Deicing fluids applied to aircraft arebecoming a concern as a source of environ-mental contamination. The mixture mostcommonly used as aircraft deicing fluid (ADF)is approximately 88% propylene glycol (PG),2.5% surfactants and corrosion inhibitors, andwater. PG may therefore be released into theenvironment at very high concentrations (onthe order of 1,000 to 100,000 mg/L). PG isreadily degradable by common soil bacteria,but if this glycol enters streams, dissolvedoxygen could be completely removed therebyimpacting aquatic life.

Studies are ongoing to determine whatimpacts bacterial degradation of PG and ADFhave on the hydrologic characteristics ofporous media. This is relevant in both naturalsoil where the deicers may be released andengineered biofilters used to treat the releases,such as those used at Norway’s new interna-

tional airport. Experiments were conducted inpacked columns (7 cm dia. x 15 cm tall) ofsand that were pre-seeded with PG-degradingbacteria that were enriched from soil. Instudies with unsaturated sand, the amount ofPCJ removed increased with spilled concentra-tion (from 1000 to 300,000 mg/L), but de-creased as multiple pore volumes of PG ordeicer were spilled.

In saturated column tests, aqueoussolutions of ADF or pure PG were circulatedthrough the columns using a peristaltic pumpat a set flow rate. Changes in the hydraulicconductivity of the sand were measured overtime, as calculated from the headloss acrossthe sand at a measured flow rate. The break-through of slug injections of bromide wereused to calculate thc dispersivity. Effluent PG,chemical oxygen demand (COD) as a bulkcarbon measurement, ammonia nitrogen, andbiomass concentrations were measured. Atthe end of a given growth period, the columnswere sacrificed to determine the total mass ofbiogrowth on the sand and its distribution withdepth in the column.

Over the range of average loading condi-tions tested of 43 to 32,000 mg PG/d, therewere faster declines in hydraulic conductivitywith higher loading up until an inhibitionthreshold was reached at around 536 mg PG/dloading. At high loadings, the ADF mixtureappeared somewhat more inhibitory than PGalone. The flow rate of water during the testswas also important, with higher flow ratesresulting in less biomass accumulation andassociated hydraulic conductivity decline.With the same average daily PG loading,hydraulic conductivity declined faster with acontinuous inflow of the same concentration ascompared to spikes of PG every 2 days.However, the final steady-state hydraulicconductivity was lower with the intermittentPG spikes. This may be due to a higherendogenous decay rate of the biomass in thecontinually loaded system versus the intermit-tently loaded system. Further investigation ofthis effect is underway. In all experiments it

Program ThreeTuesday, May 23, 2000Fate and Transport

24

THE IMPACT OF BIO-DEGRADATION OF DEIC-ING CHEMICALS INSAND COLUMNS ON THECONDUCTIVITY ANDDISPERSIVITY OF THEPOROUS MEDIA


column experiments under variable systemchemical conditions. Solutions containingU(VI) and citrate were introduced to thecolumns packed with quartz sand with anaverage particle size of 300 µm. Our experi-mental results show that U(VI) transport wasenhanced in the presence of citric acid, de-pending on system conditions such a pH andU(VI)/citric acid ratio. The U(VI) transportsimulations were obtained using RATEQ(developed by Curtis and Rubin), a reactivetransport code which incorporates a diffuse,double-layer surface-complexation model(SCM) with transport equations. The asym-metrical breakthrough curves were an indica-tion of heterogeneous sorbent surface sitesand/or a kinetically controlled adsorption/desorption surface reactions. Our transportsimulations invoking kinetically controlledsurface reactions successfully predicted thisasymmetrical behavior. The coupled SCM/transport model improved our ability to accu-rately simulate the effects of uranium/citratecomplexes on U(VI) transport relative to theuse of distribution coefficients (K

d values) to

quantify actinide/sorbent partitioning. Experi-mental results demonstrate that organic acidligands may significantly enhance metal-iontransport through porous media.

Key words: uranium, citric acid, surfacecomplexation, transport modeling

was noted that the dispersivity, as calculatedfrom bromide breakthrough curves, initiallyincreased with biogrowth but later decreasedas biofilms became more developed.

Using measured inlet and effluent PG dataimmediately before columns were sacrificedand biomass concentrations on the sand en-abled thc calculation of first-order PG biodeg-radation rates in the columns. These ratesranged from 0.6 to 1 x 10-5 L/mg bio-min.These rates are significantly slower than ratesmeasured in batch tests with the suspendedculture; pseudo first-order degradation ratesaveraged 1.4 x 10-4 L/mg bio-min. The ratedifference is likely due to a combination ofmass transfer through the biofilms and oxygenlimitation.

Understanding the effects of bacterialgrowth in sand on the hydrodynamic proper-ties of the media and the net biokinetics of thesystem will aid in predicting the fate of deicingcompounds in the natural environment andengineered treatment biofilters. The potentialfor inhibition of bacterial activity at highconcentrations is significant, as dilution may berequired before bacteria can optimally degradethe contaminants.

Key words: biofilms, porous media, deicingfluid

25

EXPERIMENTAL INVES-TIGATION AND MULTI-COMPONENT MODELINGOF URANIUM TRANS-PORT IN THE PRESENCEOF CITRIC ACID ANDUNDER VARIABLE CON-DITIONS

port those species. Dissolved organic matterconstitutes an important radionuclide-complexing ligand pool in most aquatic sys-tems. In this study, the effects of citric acid (asa natural organic matter surrogate) on thetransport of U(VI) in a saturated porous mediawere investigated with a series of batch and

1Cetin Kantar and 2Bruce Honeyman, 1,2Colo-rado School of Mines, Environmental Scienceand Engineering Division, Golden, CO80401; 1Phone number: (303) 273 3420; 1E-mail: [email protected]; 2E-mail:[email protected].

The transport of contaminants in satu-rated porous media is governed by elementspeciation and the processes that act to trans-


alkali under a nitrogen atmosphere. Theorganic matter removed by this method wasfractionated into humic and fulvic acid compo-nents, and the atrazine associated with eachcomponent was determined. Finally, theherbicide remaining on the alkali-extracted soilwas quantified by combusting the soil at 925°Cand counting the 14CO

2 on a liquid scintillation

counter. The effect of the presence of the soilenzyme, horseradish peroxidase, on the natureand extent of binding was also evaluated.

Key words: soil, pesticide, binding, atrazine,isotherms

EVALUATION OF ATRA-ZINE BINDING TO SUR-FACE SOILS

26

Program ThreeTuesday, May 23, 2000Zero-Valent Metals

1Heather Lesan and 2Alok Bhandari, Depart-ment of Civil Engineering, Kansas StateUniversity, Manhattan, KS 66506-2905;1Phone: (785) 532-7717; 1E-mail:[email protected]; 2E-mail:[email protected].

Triazine herbicides and their derivativesare major contaminants of surface water in themidwestern United States. Every spring 150million pounds of triazine herbicides areapplied to corn and grain sorghum fields in thisregion. Atrazine, (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) is the mostfrequently applied chemical and is used exten-sively as a pre-emergent broad-leaf herbicide.Although atrazine and its partial degradationproducts are relatively mobile in soil, onceapplied they can associate with a variety of soilcomponents including soil organic matter, soilsolution, or the surfaces of suspended particu-late matter such as colloids and humic or fulvicacids. Associations between organic matterand pesticides can result in either immobiliza-tion or enhanced transport of the contaminant,depending on the nature of the interaction.Our study focused on evaluating the nature ofassociation of atrazine with two Kansas sur-face soils. The soils chosen were characterizedas silty loams and belonged to the Woodsonseries. One soil was obtained from an agricul-tural field (3.4% organic matter) while theother was collected from an adjacent forestedarea (6.2% organic matter). U-ring-14C-labeled atrazine was used to improve detectionlimits and better track the distribution of theherbicide among various soil components.Bottle-point adsorption experiments withconstant soil dosage were conducted for aperiod of 7 days followed by sequential extrac-tion (desorption) with synthetic “surfacewater.” The strongly adsorbed atrazine frac-tion was removed by multiple extractions withethyl acetate. Next, the soil was extracted with

27

CONTAMINANTREMEDIATION BY IRONMETAL: SHIFTING KI-NETIC REGIMES

1Michelle Scherer, Jennifer Ginner, PedroAlvarez, and Kathy Johnson, Department ofCivil and Environmental Engineering, Univer-sity of Iowa, 4016 Seamans Center, Iowa City,IA 52242; 1Phone: (319) 335-5654, 1E-mail:[email protected].

Zero-valent metals such as iron, tin, andzinc, are moderately strong reducing agentsthat are capable of reducing many commonenvironmental contaminants. Of these metals,granular iron metal has received a great deal ofattention because of the pioneering work ofGillham and O’Hannesin. Early studies ofreduction by iron metal focused primarily onchlorinated aliphatics (RC1), and, only re-cently, has the reduction of other compoundssuch as metals, nitrate, munition wastes, andpesticides received significant attention.

Despite the uncertainty regarding theidentity of the actual reductant (i.e., Fe0,surface-bound Fe(II), or H

2) in iron-metal

systems, it is clear that the transformation


process is a surface reaction which requiresclose contact of the reactive medium and thecontaminant. Surface redox reactions arecomprised of a series of physical and chemicalprocesses including: (i) mass transport of thedissolved contaminant from a well-mixed bulksolution to the surface (ii) sorption of thecontaminant to the surface (e.g., precursorcomplex formation or surface complex forma-tion), (iii) transfer of electrons (ET) from thesurface to the contaminant, and (iv) desorptionof the contaminant from the surface. Any oneof these four steps can limit the rate of con-taminant reduction by Fe0.

To better explore the influence of each ofthese steps on rates of contaminant reductionby Fe0, we have used an electrochemical cellwith an oxide-free Fe0 rotating disk electrode(Fe0 RDE). Earlier experiments conductedwith the Fe0 RDE clearly showed a negligibleeffect of mass transport on the overall reduc-tion rate of carbon tetrachloride (CCl

4). Over

the range of conditions of interest in environ-mental applications, however, both steps couldinfluence the reaction rate, so it is not surpris-ing that some evidence for mass transporteffects has been reported in batch and columnexperiments.

A similar set of experiments with the Fe0

RDE have been conducted with a series ofnitrogen compounds, including nitrobenzene,nitrate, and nitrite. Results obtained with theFe0 RDE indicate a case of intermediatekinetics for these contaminants, where depend-ing on the conditions of the environmentalapplications, either mass transport or reactionat the surface limits the overall rate of transfor-mation. The implications of shifting betweendifferent kinetic regimes on the design andimplementation of Fe0 PRBs will be discussed.

Key words: nitrate, nitrite, nitroaromatics,permeable reactive barriers

28

DISSIMILATORY IRON-REDUCING BACTERIACAN INFLUENCE THEREDUCTION OF CARBONTETRACHLORIDE BYIRON METAL

1Robin Gerlach, 1Al Cunningham, and 2FrankCaccavo Jr., 1Center for Biofilm Engineering,Montana State University, 366 EPS Building,Bozeman, MT 59717-3980; 2Department ofMicrobiology, University of New Hampshire,Rubman Hall, Durham, NH 02824; 1Phone:(406) 994-4770; 2Phone: (603) 862-2443.

Little is known about the long-termperformance of zero-valent iron (Fe0) subsur-face barriers. Exposure to groundwater andcontaminants induces corrosion processes thatcan passivate the Fe0 surface and decreasebarrier reaction rates. We present evidence thatdissimilatory iron-reducing bacteria (DIRB)can stimulate the rate of carbon tetrachloride(CT) transformation in such cases. The DIRB,Shewanella alga BrY, adhered to Fe-surfacesthat showed little or no capacity to transformCT. The addition of BrY to systems withdecreased CT transformation rates resulted inincreased ferrous iron concentrations andincreased CT transformation to chloroform.The results suggest that DIRB can have aninfluence on the long-term performance of Fe0

barriers for the remediation of chlorinatedaliphatics.

Key words: zero-valent iron, iron-reducingbacteria, carbon tetrachloride, subsurfacebarrier


mechanism seems to indicate that regenerationof reactive sites, often a rate-limiting factor,may not be needed, and therefore, makes itvery promising for wasted industrial Fe0

powder to be used for field-scale remediationof nitrate-contaminated groundwater. Theresults also indicate that, unlike the oxidecoated on the granular iron surface, commer-cially available magnetite powder togetherwith dissolved Fe2+ do not work for nitratereduction. Therefore, special structures may berequired for smooth electron transfer.

Key words: nitrate reduction, zero-valentiron, coordinating surface, pH, magnetite

29

NITRATE REMOVALUSING WASTED INDUS-TRIAL IRON POWDER

Program OneWednesday, May 24, 2000Phytoremediation--Exudates andMetals

Batch experiments were conducted toinvestigate the mechanisms of nitrate reductionin an iron/water/nitrate system. Ten (10) mlserum bottles with rubber stoppers were usedas reactors. Oxygen was excluded by using N

2

gas to purge the reactors. In each batch test,dozens of bottles were prepared. The testswere run under different initial conditions. Theinitial pH of each batch reactor was adjustedby adding HCI or NaOH. The batch reactorswere put in a 1 ft. by 1.5 ft. box rotating at 30rpm to provide complete mixing and reducemass transfer resistance. At each predeter-mined time interval one reactor was sacrificedfor analyzing pH, ORP, NO

3-, NO

2-, Fe2+, and

Fe3+. The impacts of pH, iron (with or withoutmagnetite coating), dissolved Fe2+, and magne-tite powder on nitrate removal were studied.

The results indicate that two differentmechanisms may be involved in nitrate re-moval. At low pH (2 to 4), Fe0 corrosion isnecessary for nitrate reduction. In this case,Fe0 is the electron donor, and Fe2+ is thereaction product; NO

3- acts as the electron

acceptor and is reduced to NH4

+ (or N2).

Another mechanism is that, at pH 5 to 8, bothdissolved Fe2+ and iron oxide (in a form ofmagnetite coated on the surface of granulariron) play a major role in nitrate degradation.In this process a black precipitate, presumablymagnetite, was formed during nitrate reduc-tion. The process shows a tendency of self-acceleration as the black precipitate is formed.It seems that the oxide film acts as a coordi-nating surface for the adsorption of Fe 2+ andoccurrence of electron transfer. The second

1Yong Huang and 2Tian Zhang, 1,2Departmentof Civil Engineering, 205 PKI, University ofNebraska-Lincoln at Omaha Campus, Omaha,NE 68182-0178; 1Phone: (402) 554-3565,1E-mail: [email protected]; 2Phone:(402) 554-3784, 2E-mail:[email protected].

30

INFLUENCE OF PLANTROOT EXUDATES ONMICROBIAL POPULA-TIONS

Ken Yoshitomi and Jodi Shann, Department ofBiological Sciences, University of Cincinnati,614 Rieveschl, P.O. Box 210006, Cincinnati,OH 45221-0006; Phone: (513) 556-9765, E-mail: [email protected].

Phytoremediation has been investigated asa cost-effective option for the clean up ofcontaminated soils. Although numerous studieshave demonstrated increased degradation ofhazardous organic compounds in the soilsurrounding plant roots (the rhizosphere), littleis known about the basic mechanisms contrib-uting to this phenomena. In this study, the roleof root exudates was explored. Specifically,the influence extracted plant exudates have onsoil microorganisms.

Corn (Zea mays L.) was grown in ahydroponic apparatus designed to simulate soilwhile maintaining aseptic conditions. Solubleroot exudates were allowed to flush throughthe system and over soil columns. Microbial


characterization of the soil columns wasassessed by plate counts, microbial lipidanalysis of biomass and activity, and theirability to mineralize a radiolabeled PAH,pyrene. Community shifts in their carbonsource utilization profile were determined byBiolog™ GN analysis.

Results from the exudate amendmentstudies indicated that long-term application ofexudates to bulk soil was able to enhance themicrobial populations’ potential to mineralize14C-pyrene. However, stimulation of biomassand activity was minimal, suggesting that merenumbers or activity was not responsible for theincreased mineralization. Multivariate analysisof Biolog™ GN plates revealed functionalshifts in microbial communities betweentreatments. This data suggests exudate pres-sures may change the functional aspect of thecommunity structure, favoring degradingpopulations of bacteria.

Current studies are further investigatingthe root exudate phenomena by addressing theinfluence of extracted root exudates on twodifferent degrading genera of bacteria, a gramnegative and a gram positive. Typically associ-ated with different portions of the soil (rhizo-sphere vs. bulk soil), their responses to plantroot exudates will help elucidate the role theseexudates play for different types of bacteria.These studies will give a clearer understandingof the potential mechanisms controlling rhizo-sphere degradation.

Key words: Zea mays, root exudates, 14C-pyrene

31

LEADHYPERACCUMULATIONBY SESBANIADRUMMONDII

1Robert Barlow, 1Natalie Bryant, 1JohnAndersland, and 2Shivendra Sahi, 1,2Depart-ment of Biology, Western Kentucky University,1 Big Red Way, Bowling Green, KY 42101;Phone: 1(270) 745-6012, 1E-mail:[email protected]; 2E-mail:[email protected].

Sesbania drummondii is a leguminousplant commonly found in the southeasternUnited States. Our studies have shown thatseedlings of Sesbania drummondii canhyperaccumulate lead (Pb) in a controlledhydroponic environment. The addition of achelating compound (EDTA) further increasesthe amount of Pb that a seedling can accumu-late. Pb-treated roots were analyzed withscanning and transmission electron micro-scopes equipped with energy dispersive X-rayspectrometers. Pb deposits were observed inconcentric rings around the stele, on subepi-dermal cortical cells, and on the surface of theepidermis. The lead appeared to be localizedwithin and on the cell wall. Phosphorus waspresent wherever lead was detected, suggest-ing that the lead precipitated as a lead phos-phate. The data gathered suggests that itwould be feasible to examine the Pb accumu-lating capabilities of Sesbania drummondii in asoil environment.

Key words: phytoremediation, lead,hyperaccumulation, Sesbania, and EDTA


32

CORROBORATION OFCOPPER AND CHRO-MIUM UPTAKE BYCREOSOTE BUSH USINGHYDROPONICS: SPEC-TROSCOPIC STUDIES

1S. Arteaga, 1R.R. Chianelli, 2J.L. Gardea-Torresdey, 3W.P. Mackay, and 4N.E. Pingitore,1,2Departments of Chemistry and Environmen-tal Science and Engineering, University ofTexas at El Paso, El Paso, TX 79968; 3De-partment of Biology, University of Texas at ElPaso, El Paso, TX 79968; 4Department ofGeological Sciences, University of Texas at ElPaso, El Paso, TX 79968; 2Phone: (915) 747-5359, 2E-mail: [email protected].

Phytoremediation has developed as apotential remediation solution for contami-nated sites. Also, phytoremediation takesadvantage of the fact that plants may extractand concentrate particular elements from theenvironment. Creosote bush, or Larreatridentata, is a common desert shrub of theSouthwest, covering roughly 20 million acresfrom western Texas to California. This plant isfound growing naturally in heavy-metal con-taminated soils in the El Paso area. Previousinvestigations had found that this plant is ableto accumulate and concentrate high amountsof copper and other metals from soils in itstissues. For this reason, this plant is consideredto be a “hyperaccumulator.” Creosote bushseedlings were exposed to two differentconcentrations of copper sulfate (63.5 ppmand 635 ppm) during 48 hours using hydro-ponics. Another set of plants were exposed toK

2Cr

2O

7 (520 ppm Cr+6) and Cr(NO

3)

3 (520

ppm Cr+3) for the same period of time. Theroots, stems, and leaves of the plants wereanalyzed by atomic absorption spectroscopygiving positive copper and chromium uptakeresults. The different parts of the plants wereanalyzed using X-ray absorption spectroscopy.Also, the copper and chromium laden plant’stissues were analyzed with X-raymicrofluorescence. Results of our experimentswill be presented. We are currently performingexperiments for the uptake of Cr+6 and Cr+3 by

living creosote bush seedlings. The results ofthose experiments will also be presented.

Key words: phytoremediation, soil contami-nation, creosote bush, XAS, XRMF

1J.R. Peralta, 1K.J. Tiemann, 1S. Arteaga, 1E.Rascon, 1J.G. Parsons, 1E. Gomez, and 2J.L.Gardea-Torresdey, 1,2Department of Chemistryand Environmental Science and Engineering,University of Texas at El Paso, El Paso, TX79968; 2Phone: (915) 747-5359, 2E-mail:[email protected].

Heavy metals contamination is a trouble-some environmental problem in many indus-trial countries, and phytoremediation technolo-gies are promising solutions to clean a varietyof pollutants. Preliminary studies have shownthat live alfalfa plants (Medicago sativa) cansurvive in heavy metal-contaminated soils.Therefore, we decided to study the metaluptake abilities of live alfalfa plants using solidmedia. The objective of this study was todetermine the effects of Cd(II), Cr(III), Cu(II),Ni(II), and Zn(II) on seed germination andplant growth in alfalfa. The heavy metalconcentrations in the growth media variedfrom 0, 10, 20, and 40 ppm for each metal ionstudied. Following two weeks of growth,germination rate, root, and shoot length wererecorded along with the metal content. Resultsof these experiments indicate that Cd(II)concentrations reduced the shoot growth by54%, 70%, and 100%, respectively. Theresults for the other metal ions studied alsoreduced growth respective to the increasing

33

STUDY OF METAL UP-TAKE AND PLANTGROWTH ON LIVE AL-FALFA PLANTS GROWNIN SOLID MEDIA

Program OneWednesday, May 24, 2000Phytoremediation--Metals andDeicers


metal content by the following amounts:Cr(III) 31%, 54%, and 93%; Cu(II) 12%,37%, and 67%; Ni(II) 17%, 30%, and 63%.However, the presence of Zn(II) enhanced thegrowth of plants and it overpassed the controllength by 4% with the doses of 10 and 20 ppm.The doses of 20 and 40 ppm of Cd(II), Cr(III),and Cu(II) affected the germination rate bymore than 40%. These results indicate thefeasibility of using live alfalfa plants in theremediation of moderately, heavy-metal con-taminated soils.

Key words: phytoremediation, alfalfa,Medicago sativa, solid media

lyzed by glutamyl-cysteine synthetase (ECS),and glutathione synthetase (GS), respectively.To obtain plants with superior metal accumula-tion and tolerance, we overexpressed the E.coli ECS and GS enzymes in Brassica juncea(Indian mustard), a particularly suitable plantspecies for heavy metal remediation. Thetransgenic ECS and GS plants containedhigher levels of glutathione and phytochelatinsthan the wildtype plants. The ECS and GSplants accumulated up to 3-fold more cad-mium in their shoots than wildtype plants, andalso showed enhanced cadmium tolerance. Inanother study, we overexpressed the keyenzyme of the sulfate assimilation pathway, i.e.ATP sulfurylase (APS). The resulting APSplants accumulated significantly (up to 3-fold)more selenium, molybdenum, and sulfur thanwildtype plants. We conclude that plantgenetic engineering is a promising strategy forthe production of plants with superiorphytoremediation capacity. These transgenicplants are presently analyzed with respect totheir tolerance and accumulation of othermetals, and used in phytoremediation studiesof metal-polluted mine drainage in Leadville.

Key words: phytoremediation, metals, sele-nium, phytochelatins

1Elizabeth Pilon-Smits, 2Yong Liang Zhu,3Kerry Hale, 3Marinus Pilon, and 4NormanTerry, 1,3Department of Biology, ColoradoState University, A/Z Building, Fort Collins,CO 80523; 2,4Department of Plant and Micro-bial Biology, University of California atBerkeley, 111 Koshland Hall, Berkeley, CA94720; 1Phone: (970) 491-4991, 1E-mail:[email protected]; 4E-mail:[email protected].

Phytoremediation, i.e. the use of plantsfor environmental cleanup, offers an attractiveand cost-effective approach to remediatemetal-polluted soils and waters. The goal ofthese studies is to use genetic engineering toincrease metal tolerance and accumulation inplants, so as to create better plants for metalphytoremediation. In one of our studies, wehave overproduced the metal-binding peptidesglutathione and phytochelatins. Glutathioneplays several important roles in the defense ofplants against environmental stresses, and isthe precursor for phytochelatins (PCs): heavymetal-binding peptides involved in metaltolerance and sequestration. Glutathione issynthesized in two enzymatic reactions, cata-

1Sigifredo Castro, 2Lawrence Davis, and1Larry Erickson, 1Department of ChemicalEngineering, Kansas State University, Man-hattan, KS 66506; 2Department of Biochemis-try, Kansas State University, Manhattan, KS66506; 1Phone: (785) 532-5584, 1E-mail:[email protected]; 2Phone: (785) 532-6121.

Aircraft deicer fluids (ADF) and anti-freeze solutions are mainly constituted byeither propylene or ethylene glycol and addi-tives such as benzotriazole methyl substitutionisomers (tolyltriazoles). The glycols are

34

ENHANCEDPHYTOREMEDIATIONEFFICIENCY THROUGHPLANT BIOTECHNOL-OGY

35

PHYTOREMEDIATION OFAIRCRAFT DEICER ANDANTIFREEZE FORMULA-TIONS


present in concentrations that vary from 20 to95 % and the triazoles at levels up to 1 g/L.The ADFs are used and discharged to theenvironment in large quantities, constituting aterrestrial and aquatic environmental risk.Although the in situ biodegradation of glycolshas been achieved under controlled conditions,the breakdown products, (bio)degradationpotential, and mode of toxicity of the triazolesremain uncertain. Triazoles are identified aspossible carcinogens and inducers of toxicresponses in aquatic flora and fauna. It isknown that an enzyme able to degrade triazoleis the lignin peroxidase, expressed by white-rotfungus, Phanerochaete chrysosporium. Theenzyme is also the catalyst in the lignificationprocess in higher plants, a fact that allowed usto propose a plant-based remediation processto economically detoxify the triazoles in theADF. We found a threshold for toxicity oftriazoles to common grass used at airports,and to sunflower, of about 0.1 mg/mL. Differ-ent methods to extract the triazoles from thetreated plants were explored and it was notpossible to recover them, indicating that thetriazoles are being incorporated covalently tothe plant structure. However, the presence ofglycols in the ADF mixture generates anobstacle for the plant to immobilize thetriazoles since during the biodegradation of theglycols, nutrient competition, nutrient deficien-cies, and/or anaerobic conditions affect thenormal development of plants. We are investi-gating ways to promote the biodegradation ofboth contaminants by modifying culture condi-tions and to determine the metabolic fate ofthe triazole.

Key words: deicer, glycol, triazole, biodegra-dation, phytoremediation

Program OneWednesday, May 24, 2000Phytoremediation--Explosives andMTBE

36

PHYTOPHOTOLYSIS: ANEW MECHANISM FORPLANT-BASEDREMEDIATION OF RDXCONTAMINATION

1Craig Just and 2Jerald Schnoor, 1,2The Uni-versity of Iowa, Department of Civil andEnvironmental Engineering, Iowa City, IA52242; 1Phone: (319) 335-5051, 1E-mail:[email protected]; 2Phone: (319) 335-5647, 2E-mail: [email protected].

The EPA describes phytoremediationas the direct use of living green plants for insitu risk reduction for contaminated soil,sludges, sediments, and groundwater, throughcontaminant removal, degradation, or contain-ment. Phytoremediation has been utilized atmany hazardous waste sites where moretraditional remediation technologies are costprohibitive. Uptake of explosive compounds,such as 2,4,6-trinitrotoluene (TNT) andhexahydro-1,3,5-trinitro-1,3,5-triazine (RDX),by plants has been shown to occur at someU.S. Army installations including the IowaArmy Ammunition Plant (IAAP). An engi-neered wetlands system has been installed atIAAP to remediate contaminated soil andgroundwater near Brush Creek. Research intothe fate of RDX in wetland plants has beeninitiated to help determine what constitutes“success” in this application ofphytoremediation.

Regulators have been inclined todeclare a remediation strategy successful whenthe final concentration of the priority contami-nant, in this case RDX, falls below a risk-basedaction level in the soil or water. Forphytoremediation of RDX, this criterion maybe inadequate due to the possibility of accumu-lation of RDX and/or RDX metabolites inplant tissues. Many plants, including poplartrees, reed canary grass, parrot feather, and


water plantain, have been shown to readilyuptake and translocate RDX. Surveys by theUniversity of Iowa at the IAAP showed RDXconcentrations ranging from 0.5 to 2.9 mg/kgin plants growing in contaminated soil. Reedcanary grass at the site showed the highestlevels of RDX compared to other plant types.Reed canary grass has the highest watertranspiration rate of the species sampled,which could explain the elevated RDX levels.It’s also possible that reed canary grass accu-mulates more RDX then other plant species.Studies in our laboratory with 14C-RDX andreed canary grass have provided evidencesupporting the formation of formaldehydewithin the plants with subsequent loss of theatmosphere. The proposed mechanism oftransformation, termed “phytophotolysis,”involves the translocation of contaminants tothe leaves of plants with subsequent photolysisdue to light exposure. This newphytoremediation mechanism could proveuseful for treatment of photoactive compoundsin shallow groundwater that might otherwisenot be exposed to sunlight.

Key words: phytophotolysis, RDX, wetlands,IAAP, formaldehyde

37

BIOTRANSFORMATIONOF 2,4,6-TNT INPHYTOREMEDIATIONSYSTEMS: CONJUGA-TION AND OXIDATION

facilities continues to be a serious challengedue to the recalcitrance of explosives in theenvironment. The primary culprit is thenitroaromatic compound 2,4,6-trinitrotoluene(TNT) and related synthesis by-products.Phytoremediation or plant-drivenbioremediation is gaining prominence as aviable, low-cost option for the amelioration ofTNT-contaminated media. This paper pre-sents studies that elucidate pathways ofbiotransformation of TNT in plants, other thanand beyond initial reduction of TNT, namelyconjugation and oxidation of TNT and me-tabolites. These aspects of nitroaromaticmetabolism in phytoremediation systems haveremained largely uninvestigated, but constitutesignificant metabolic fate as evidenced by ourfindings.

Our previous studies with the aquaticspecies (Myriophyllum aquaticum) and axenicroot cultures (of the terrestrial plant,Catharanthus roseus) have shown the signifi-cant activity of the reductive pathways, leadingto the formation of 2-amino-4,6-dinitrotolueneand 4-amino-2,6-dinitrotoluene. Beyond theinitial reduction of TNT, our present studieswith axenic roots of C. roseus show thatbiotransformation of reduced TNT derivativesoccurs by plant-specific conjugation processes,where a plant-associated carbon skeleton isadded to the aryl-amino group. Conjugatedderivatives of both 2-amino-4,6-dinitrotolueneand 4-amino-2,6-dinitrotoluene have beenisolated from the biomass and aqueous phase,and characterized by HPLC-UV, 1H- and 13C-NMR spectroscopy, and mass spectroscopy.The conjugated derivatives of TNT representsignificant metabolic fate in plants and con-form to models of xenobiotic metabolism inplants.

Since reduction products and their conju-gates do not completely account for TNTdisappearance from the contaminated phase,TNT metabolism in plants was also investi-gated for possible oxidative transformation.These studies were conducted with the aquaticplant M aquaticum. TNT-metabolites wereisolated from the aqueous matrix, providing

1R. Bhadra, 2R.J. Spanggord, 3J.V. Shanks,and 4J.B. Hughes, 1Dept. of Chemical &Bioresource Engineering, Colorado StateUniversity, Ft. Collins, CO;2Biopharmaceutical Development Division,SRI International, Menlo Park, CA; 3Dept. ofEnvironmental Science & Engineering, RiceUniversity, Houston, TX; 4Dept. of ChemicalEngineering, Iowa State University, Ames, IA;1Phone: (970) 491-2227, 2E-mail:[email protected].

The cleanup of explosives-contaminatedsoil and water at numerous defense-sector


conclusive evidence for oxidation of the ring-substituted methyl-group and aromatic hy-droxylation. These compounds include 2-amino-4,6-dinitrobenzoic acid; 2,4-dinitro-6-hydroxy-benzyl alcohol; 2-N-acetoxyamino-4,6-dinitrobenzaldehyde; and 2,4-dinitro-6-hydroxytoluene. It is possible that oxidativetransformation(s) preceded nitro-reductionsince studies on exposure of M. aquaticum toeither 2-amino-4,6-dinitrotoluene or 4-amino-2,6-dinitrotoluene did not yield any of theoxidized products identified. The accumula-tion of oxidized products was significant: 2-amino-4,6-dinitrobenzoic acid, 4.4%; 2,4-dinitro-6-hydroxy-benzyl alcohol, 8.1%; 2-N-acetoxyamino-4,6-dinitrobenzaldehyde, 7.8%;and, 2,4-dinitro-6-hydroxytoluene, 15.6%.These studies, and their implications of thefindings to the environmental fate andphytoremediation applications for explosives,will be discussed.

Key words: explosives, phytoremediation,metabolism, fate, wetlands

38

PHYTOREMEDIATIONOF METHYL-TERT-BUTYL-ETHER (MTBE)

MTBE plume develops rapidly that is difficultto remediate by conventional methods.Phytoremediation is an innovative technologythat utilizes plant systems to remediate hazard-ous waste sites. Phytoremediation is anefficient mechanism of contaminant removalfor compounds whose octonal-water partitioncoefficient, log K

o/w, is between 1 and 3. Since

the Log Ko/w

for MTBE is 1.24, which is in therange that is readily transpired in plants andtrees, phytoremediation may be a feasibleremedial technique for subsurface MTBEplumes. Plants and trees may transpire manyvolatile-organic compounds (VOCs) into theair. While MTBE does not degrade in soil,atmospheric MTBE reacts with hydroxylradicals in air, yielding a half-life in the orderof days. Thus, transpiration of MTBE fromthe subsurface to air via plants can offer a low-cost method for destruction of the pollutant tobenign products. Currently, there is no dataavailable for removal of MTBE from waterdue to plant transpiration.

The objective of this project is to examinethe potential for phytoremediation of MTBE-contaminated waters using poplar trees.Poplar trees (populus deltoids x nigra) wereselected for this project because they arehardy, rapid-growing phreatophytes. Aclosed-chamber system was developed toquantify MTBE movement through the poplartree’s roots, shoots, leaves, and finally to theair. Experimental data showed the following:

♦ 69-80% reduction in MTBE mass.♦ 46-56% reduction in MTBE concentra-

tion.♦ MTBE was extracted from plant roots

and shoots at a concentration of 5-10ppb, indicating MTBE movementthrough the plant.

These results indicate that MTBE wasreadily taken up by hybrid poplar saplings inthe laboratory. Ongoing experiments areevaluating MTBE phytoremediation in larger-scale soil-water systems.

1Ellen Rubin and 2Anu Ramaswami, 1,2Depart-ment of Civil Engineering, University ofColorado-Denver, Campus Box 113, PO Box173364, Denver, CO 80217; 1Phone: (303)556-4734, 1E-mail: [email protected]; 2E-mail: [email protected].

Methyl-tertiary-butyl-ether (MTBE) isused as a gasoline additive in EPA’s oxyfuelsprogram. MTBE in fuel can help control airpollution, but it is a potential water andgroundwater pollutant. MTBE has been foundwidespread across the nation in municipalsupply wells, irrigation wells, and groundwatermonitoring wells.

MTBE is very water-soluble and does notsorb much to soil; it is also essentially non-biodegradable and non-reactive in water.Therefore, once MTBE gets into water, an


Key words: phytoremediation, MTBE graphical user interface decision supportsystem that will allow the environmentalprofessional to calculate specific parameters,such as time of treatment, regarding the site.The last tool is a manual detailing answers tovarious questions regarding vegetated treat-ment options. In this presentation, a multime-dia decision support system, combining thesetools, will be shown. A short introduction tothe problem and the need for this solution willbe followed by a demonstration on the use ofthe product for a particular case study. Addi-tional information regarding product develop-ment will be covered as needed during thepresentation.

Key words: phytoremediation, petroleumhydrocarbons, contaminated soil, vegetation

1R. Kathikeyan, 1K.R. Mankin, 2PeterKulakow, 2G. Pierzynski, 3Blase Leven, and3Larry Erickson, 1Department of Biologicaland Agricultural Engineering, Seaton Hall,Kansas State University, Manhattan, KS66505; 2Department of Agronomy, 2004Throckmorton Plant Science Center, KansasState University, Manhattan, KS 66506-5501;3Great Plains/Rocky Mountain HSRC, 101Ward Hall, Kansas State University, Manhat-tan, KS 66506; 1Phone: (785) 532-2923, 1E-mail: [email protected]; 2Phone: (785) 532-7239, 2E-mail: [email protected]; 3Phone:(785) 532-6519, 3E-mail: [email protected].

Army training reservations contain ve-hicle wash facilities where combat and otherequipment are washed after field maneuvers.During this process, sediments containingsignificant concentrations of petroleum hydro-carbons accumulate in concrete sedimentationbasins. Conventional treatment methods todecontaminate these sediments include landfill

Program OneWednesday, May 24, 2000Phytoremediation--Sediments andSludges

1Suzette Burckhard, 2Kipp Thompson, 2VernonSchaefer, 3Peter Kulakow, 4Blase Leven, and5A. Paul Schwab, 1,2Civil and EnvironmentalEngineering Department, Box 2219, SouthDakota State University, Brookings, SD57007; 3Department of Agronomy, 2004Throckmorton Plant Science Center, KansasState University, Manhattan, KS 66506;4Great Plains/Rocky Mountain HSRC, 101Ward Hall, Kansas State University, Manhat-tan, KS 66506; 5Department of Agronomy,Purdue University, West Lafayette, IN47907-1284; 1Phone: (605) 688-5316, 1E-mail: [email protected];3Phone: (785) 532-7239, 3E-mail:[email protected]; 4Phone: (785) 532-0780,4E-mail: [email protected]; 5Phone: (965)496-3602, 5E-mail:[email protected].

The design of a vegetated treatmentsystem requires a vast amount of knowledgeregarding plants, climate, soils, contaminants,and their interactions. Most practicing environ-mental professionals do not have this back-ground. As a method to bridge the gap ofknowledge needed in designing a vegetatedtreatment option, a series of decision supporttools were designed. The first tool was anintroductory pamphlet of information regard-ing vegetated treatment options. The secondtool was a decision support tree to help envi-ronmental professionals choose vegetationtypes for a particular site. The third tool is a

39

VEGETATED TREAT-MENT OF VEHICLEWASH SEDIMENTS:DESIGN OF A MULTI-MEDIA AID DECISIONSUPPORT SYSTEM

40

VEGETATED TREAT-MENT OF VEHICLEWASH SEDIMENTS: AFIELD DEMONSTRA-TION


disposal or land application. However, vegeta-tive remediation systems may offer a cost-effective alternative. A phytoremediationdesign that reduces petroleum hydrocarbons toacceptable levels and is simple to implementand maintain was developed for the CentralVehicle Wash Facility (CVWF), Fort Riley,Kansas. This paper presents a brief outline ofsite characterization, vegetation treatmentsystem design, and complete results for a two-year study.


1R. Karthikeyan, 2Lawrence Davis, 3LarryErickson, and 4K.R. Mankin, 1,4Department ofBiological and Agricultural Engineering, 147Seaton Hall, Kansas State University, Man-hattan, KS 66506; 1Phone: (785) 532-2923;1Phone: (785) 532-2911; 2Department ofBiochemistry, Kansas State University, Man-hattan, KS 66506; 2Phone: (785) 532-6124;3Department of Chemical Engineering, Kan-sas State University, Manhattan, KS 66506.3Phone: (785) 532-4313; 4Department ofBiological and Agricultural Engineering,Kansas State University, Manhattan, KS66506; 4Phone: (785) 532-2911.

Jet fuels are supplied in several differentgrades to the U.S. Army. The U.S. Armyswitched from using JP-4 to using JP-8; thefate of JP-8 is not yet known in soil systems.A preliminary experiment was conducted forsix months to study the fate of JP-8 in veg-etated soil chambers and columns. The resultssuggested that biodegradation is also a majorfate of JP-8 in vegetated columns. Anotherstudy is underway to assess the influence ofplant-induced upward water movement on JP-8 transport and biodegradation in soils. Sixsoil columns, three of which are planted with

6-8 alfalfa plants and three of which areunplanted, are used to study the fate of JP-8.A constant groundwater table is maintained at10 cm from the bottom of the column, and a10 cm contaminated layer is placed on top ofthe groundwater table. The rest of the columnis filled with clean soil. This paper will presentthe experimental and modeling results of thestudy.

1Paul Olson and 2John Fletcher, 1BiologyDepartment, Colorado State University, E414A/Z Building, Ft. Collins, CO 80523; 2Depart-ment of Botany and Microbiology, Universityof Oklahoma, 770 Van Vleet Oval, Norman,OK 73019; 1Phone: (970) 491-3320, 1E-mail:[email protected]; 2Phone: (405)325-3174, 2E-mail: [email protected].

Examination of volunteer vegetationgrowing in industrial sludge contaminated withpolycyclic aromatic hydrocarbons (PAHs) hasbeen used as a means of identifying particularplant species whose roots foster soil restora-tion and the degradation of organic contami-nants. Aerial photographs taken over the last25 years have been used to characterize plantinvasion and plant succession that has resultedin the development of a diverse and healthycommunity of plants (51 species from 22families) currently growing at this contami-nated site. Differences between the plantcommunity composition at the contaminatedsludge basin and a non-contaminated sitesuggested that a select group of plants havefavorable characters that the presence of plantroots growing in the contaminated sludgecorresponded with a visual soil restoration anddissipation of recalcitrant PAHs. The distribu-tion and depth of plant roots from tolerantvegetation growing at this former sludge basinwere species and age dependent. In general,

EXPERIMENTAL ANDMODELING STUDIES ONJET FUEL MOVEMENTIN VEGETATED SOILCOLUMNS41

42

THE ROLE OF VEGETA-TION IN THEPHYTOREMEDIATIONAND ECOLOGICAL RE-COVERY OF HAZARD-OUS WASTE SITES


tree and shrub roots penetrated the sludge to agreater extent (~90 cm), compared to grasses(~50 cm) and forbs(~60 cm) at this site.However, PAH levels were significantly lowerwithin the root zone (10-25% the concentra-tion present beneath the root zone) regardlessof the vegetation compared to the non-rootedsludge. Thus tolerant vegetation invaded andcolonized a former sludge basin, and throughextensive root growth, fostered the naturalattenuation and ecological recovery. Theresults from this study support the concept thatan established plant community with associ-ated microorganisms provides an ecologicallystable, low cost, sustained bioremediationsystem for long-term treatment of sludgebasins.

Key words: phytoremediation, polycyclicaromatic hydrocarbons (PAHs),bioremediation, plant invasion and succes-sion, ecological recovery

1Barbara Kramer and 2P. Barry Ryan, 1De-partment of Chemistry, Emory University,Atlanta, GA 30322; 2Rollins School of PublicHealth, Emory University, Atlanta, GA 30322;1Phone: (404) 727-9259, 1E-mail:[email protected]; 2Phone: (404) 727-3826, 2E-mail: [email protected].

The inadvertent ingestion of contami-nated soil can be an important source ofpesticide exposure, especially in young chil-dren. The actual level of a pesticide that isavailable for absorption into a biological

system may be much lower than the overallcontamination level due to the interaction ofeach chemical with the solid matrix. Thisbioaccessibility is dependent on characteristicsof the chemical species as well as the soil typeand residence time of the compound in the soil.In an effort to improve understanding of thisphenomenon, we report a comparison of therecoveries of pesticides spiked into threemodel solids, as well as soil using differentanalytical extraction techniques, microwave-assisted extraction (MAE), and Soxhlet extrac-tion. The efficiencies of these techniques arefurther compared to the results of a physi-ologically based extraction test (PBET) thatestimates the bioaccessibility of each com-pound to examine the potential use of eachextraction technique in bioavailability studies.

Key words: bioaccessibility, pesticides, soil,extraction

1R. Hurtado and 2J.L. Gardea-Torresdey,1,2Department of Chemistry and Environmen-tal Science and Engineering, University ofTexas at El Paso, El Paso, TX 79968; 2Phone:(915) 747-5359, 2E-mail: [email protected].

Fluoride content in tap water presentspublic health risks, mainly when the contentsare over the regulation limits. The toxiceffects of fluorides include enzyme damage,which results in a wide variety of chronicdiseases. There are numerous scientific studieslinking fluoride to increased risk of hip frac-ture, cancer, genetic damage, bone pathology,premature aging, and dental Fluorosis, amongother health risks. In Mexico, the maximumallowable level of fluoride in drinking water is1.5 mg/L. The objective of this study was todetermine the fluoride content in drinkingwater from more than 20 sites located in “LosAltos de Jalisco” in the Central Region of

43

SOXHLET AND MICRO-WAVE EXTRACTION INDETERMINING THEBIOACCESSIBILITY OFPESTICIDES FROM SOILAND MODEL SOLIDS

Program TwoWednesday, May 24, 2000Bioavailability and Risk

44

FLUORIDE OCCURRENCEIN TAP WATERS AT “LOSALTOS DE JALISCO” INTHE CENTRAL MEXICOREGION


Mexico. Water samples were obtained fromwells and surface reservoirs following propersampling procedures. The samples wereanalyzed electrochemically, using the approvedUS EPA ion-selective method (Method 340.2).“Los Altos de Jalisco” is located in the neo-volcanic belt of the Central Mexico Regionwhere most of the waters have a naturalcontent of fluoride. Based on the results ofthis study, the content of fluoride in some citiessuch as Mezticacan (7.5 mg/L), Encarnacionde Diaz (4.3 mg/L), Lagos de Moreno (4.8mg/L), Temacapulin (11.4 mg/L), andTepatitlan (6.8 mg/L) represents a serioushealth risk and should be of major concern.This presentation will discuss the geochemistryof the waters and will present some methodsor suggestions for the defluoridation of thewater of each locality.

Key words: fluoride, fluorosis, defluoridation,public health, ion-selective

David Kurz, EnviroGroup Limited, 7208 S.Tucson Way, Suite 125, Englewood, CO;Phone: (303) 790-1340, E-mail:[email protected].

This paper presents information on thereliability of making risk-based correctiveaction (RBCA) decisions using ASTM meth-ods for groundwater remediation and indoorair mitigation in residences located over ashallow groundwater plume contaminated withchlorinated compounds, based on the predictedconcentrations of the compounds in indoor air.

Indoor air quality (IAQ) testing resultsfor 153 residential homes in 1998 at a site inDenver, Colorado, were evaluated in thisstudy. The homes overlie groundwater with1,1 DCE concentrations ranging up to ap-proximately 1,000 µg/1, resulting from thedegradation of both 1,1,1 TCA and TCE.

Concentrations of 1,1 DCE in indoor airranged up to 91 µg/m3 in residences locatedover the plume and were generally belowdetection in homes beyond the detectablegroundwater plume. Variance of results fromhouse to house is significant (plus or minus anorder of magnitude in some cases), due to site-specific geological, building, and ventilationfactors.

One method that could have been used todecide whether indoor air mitigation systemsor groundwater remediation were necessarywas the Standard Guide for Risk-Based Cor-rective Action Applied at Petroleum ReleaseSites (ASTM E1739-95). Indoor air concen-trations were calculated considering the 1,1DCE concentration in groundwater, the depthto groundwater, and effective diffusion coeffi-cients for the progressive movement of 1,1DCE from the groundwater surface to thecapillary fringe to the vadose zone throughfoundation/slab cracks into the residentialstructure at each location.

The probability of false negatives (i.e.,homes above the action level being predictedto be below the action level) was evaluated forthe homes in this study using the actual IAQtest results for 1,1 DCE. The overall falsenegative rate was approximately 10%. How-ever, this rate was not consistent across therange of 1,1 DCE concentrations in thegroundwater plume. The rate of the falsenegative decisions appeared to be correlated tothe concentrations of 1,1 DCE in the ground-water. IAQ testing demonstrated that theestimates yielded false negative rates varyingfrom 5%, in homes above groundwater with1,1 DCE concentrations below 10 µg/L, toover 50%, in homes above groundwater with1,1 DCE concentrations of 50 µg/L. At 1,1DCE concentrations greater than 100 µg/L ingroundwater, there would have been no falsenegative decisions, but the false positive ratewas approximately 15%. Based on the resultsof this evaluation, indoor air quality (IAQ)testing should be used, rather than RBCApredictive modeling, to establish the extent ofimpacts and determine the need for mitigation.

45

ESTIMATING RESIDEN-TIAL INDOOR AIR IM-PACTS DUE TO GROUND-WATER CONTAMINA-TION


Program TwoWednesday, May 24, 2000NAPLs

Key words: risk, residential, decisions, chlori-nated, groundwater

each column section, as well as the entirecolumn.

From the scan of the dissolved hydrocar-bons, primarily BTEX over time, the relation-ship between NAPL saturation, aqueous-phasevelocity, length-of-dissolution path, and disso-lution rate were determined. This correlationprovides critical input for a numerical model(UTCHEM) to simulate the dissolution in onedimension, and coupled with scale relation-ships developed numerically, the mass transfercorrelation of large systems are predicated.

Key words: dissolution, saturation, transport,dimension, simulation

1Tarek Saba and 2Tissa Illangasekare, 1,2Divi-sion of Environmental Science and CivilEngineering, Colorado School of Mines,Golden, CO 80401-1887; 1Phone: (303) 273-3483, 1E-mail: [email protected];2Phone: (303) 384-2126, 2E-mail:[email protected].

The lack of understanding of the complexbehavior of nonaqueous-phase liquids(NAPLs) in heterogeneous systems has re-sulted in improper model conceptualizationand validation. The primary goal of a projectcurrently in progress is to develop a protocolfor validation of multi-phase flow models.Data that focuses on the influence of heteroge-neity on the behavior of NAPLs in the subsur-face will be compiled. This data on NAPLsubsurface entrapment and dissolution will beplaced in a data bank. Candidate numericalmodels that simulate NAPL behavior in thesubsurface, including FEHM, TOUGH2, andUTCHEM, will all be studied and used in thisresearch.

This paper presents results from a pre-liminary investigation where simulations areperformed on dissolution of entrapped NAPLs.

46

LNAPL DISSOLUITON INAQUEOUS LIQUID:LABORATORY COLUMNEVALUATION AND NU-MERICAL SIMULATION

1,2Dongping Dai, 1Tissa Illangasekare, and2,3John Ewing, 1Environmental Science andEngineering Division, Colorado School ofMines, Coolbaugh Hall, 14th and Illinois St.,Golden, CO 80401; 2Duke Engineering &Services, 9111 Research Blvd Austin, TX78758; 1Phone: (303) 384-2126, 1E-mail:[email protected]; 2Phone: (303) 384-2237, 2E-mail: [email protected]; 3Phone:(512) 425-2065, 3E-mail:[email protected].

Understanding of the fate and transport ofnonaqueous-phase liquid (NAPL) and dis-solved NAPL constituents, such as BTEX, isimportant in design and implementation ofNAPL-contaminated site cleanup. This labora-tory column study is designed to better under-stand dissolution of BTEX from the LANPL atlow saturation into water at one-dimension,and scale up to the larger scale with numericalsimulation.

Soil cores and LNAPL from an LNAPL-contaminated site were used in the columntest. Segments of the core were packed intocolumns in eight, 3-inch sections, each columnsection facility with ports for both samplingand monometer. This design made possibleevaluating dissolution at a range of samplelengths during one column test. The residualLANPL saturations of the columns wereestimated with a partitioning tracer techniqueat the beginning of the dissolution process for

47

A PROTOCOL FORMULTI-PHASE NUMERI-CAL MODEL VALIDATION


Results show the sensitivity of different modelsto input parameters and the resulting effects onthe model predictions. These results will beused to develop guidelines on tolerances ininput data errors and the resulting modeloutputs. Future studies will demonstrate asystematic approach to define which physicaland chemical parameters are important inmodel applications involving regulations anddesign. The findings of this work will helpresearchers in the identification of the criticalparameters in subsurface NAPL investigationsand will aid in improving technologies andcharacterization methods to obtain theseparameters in the field.

Key words: multi-phase, NAPL, dissolution,numerical, models

48

A MULTI-SCALE LABO-RATORY ASSESSMENTOF CLEANUP ENDPOINTFOR A NAPL-CONTAMI-NATED SITE

1Frank Barranco Jr., 2Tarek Saba, 3DongpingDai, 4Tissa Illangasekare, 5Denton Mauldin,6Ken Vogler, and 7Mike Klein, 1,2,3,4 Environ-mental Science and Engineering Division,Colorado School of Mines, Coolbaugh Hall,14th and Illinois St., Golden, CO 80401;5,6,7Safety-Kleen Consulting, 5665 FlatironParkway, Boulder, CO 80301; Phone: (303)938-5500; 5E-mail: [email protected]; 1Phone: (303) 384-3427, 1E-mail:[email protected]; 2E-mail:tsaba@,mines.edu; 3E-mail:[email protected]; 4E-mail: [email protected]; 6E-mail: Kvogler@,Safety-Kleen.com;7E-mail: Mklein@ Safety-Kleen.com.

Pore-scale, meso-scale, and pilot-scalestudies have been conducted in the laboratoryto assess the performance of several subsur-face restoration technologies for their potentialto meet groundwater beneficial use require-ments outlined in a Record of Decision for apetroleum-contaminated site. Pilot studies atthe field scale were deemed infeasible due to

the inability to fully characterize subsurfaceheterogeneities and the resulting distribution oflight nonaqueous-phase liquid (LNAPL).Remedial Action Objectives in the interimlocality of the site were geared toward restor-ing groundwater to domestic and industrialnonconsumptive use, and protecting currentand future users from pumping well impactscaused by diesel fuel in the form of LNAPLand/or hydrocarbon sheen. Because compli-ance with beneficial-use criteria required anunderstanding of the conditions influencingmobilization and entrapment of nonaqueous-phase hydrocarbons, controlled laboratorystudies have been performed to determineLNAPL residual saturation resulting in no freehydrocarbon mobilization from representativesoil samples. Measured residual saturationwas utilized, subsequently, as an “endpointhydrocarbon saturation” for evaluatingwhether specified restoration technologiessufficiently reduced LNAPL saturation toendpoint levels. Because of the high degree ofspatial variability of soil characteristics in thesubsurface at the study site, it was expectedthat end-point conditions, as defined by re-sidual LNAPL saturation, would also varyspatially at the field scale. In order to incorpo-rate this variability, the laboratory experiments(to determine residual LNAPL saturation andto assess the performance of several subsur-face restoration technologies) were conductedwithin intermediate-scale experimental cells.Production of free product and/or aqueoussheen from an array of sampling ports wasspatially and temporally correlated to LNAPLsaturation within the cells to assess endpointcompliance for the technologies evaluated.This information is beneficial for use withfuture field-pilot studies and determining thefeasibility and performance of applicablerestoration technologies.

Key words: NAPL, technology assessment,remediation, endpoints


Mössbauer Spectroscopy to verify its structureand composition. Preliminary experimentsreveal chromate removal rates that are bothrapid (half-lives less than ten minutes) anddirectly proportional to the concentration ofgreen rust. The strong influence of green rustconcentration on chromate disappearanceconfirms that the transformation is surface-mediated. Investigation into the role of ad-sorption and ion exchange of chromate withgreen rust interlayer anions has reveled thatthese processes appear to be limited or notoccurring due to the rapid reduction of chro-mate by either structural or surface boundFe(II) on the green rust. Further work isunderway to identify thc properties and struc-ture of the Cr(III) precipitate; previous re-search suggests this is a Fe,Cr(OH)

3 oxide.

Additional research is underway to evaluatethe effect of pH, mixing intensity, and initialchromate concentration.

Key words: green rust, chromate, abioticreduction, reduced-iron minerals

50

REMOVAL AND RECOV-ERY OF CR(III) ANDCR(VI) WITH ALFALFABIOMASS

1K. Dokken, 1K.J. Tiemann, 1G. Gamez, 1J.G.Parsons, 1I. Herrera, 2J.L. Gardea-Torresdey,and 3N.E. Pingitore, 1Department of Chemis-try, University of Texas at El Paso, El Paso,TX 79968; 2Department of EnvironmentalScience and Engineering, University of Texasat El Paso, El Paso, TX 79968; and 3Depart-ment of Geological Sciences, University ofTexas at El Paso, El Paso, TX 79968; 2Phone:(915) 747-5359, 2E-mail: [email protected].

Contamination of ground and surfacewaters by trivalent and hexavalent chromiumhas become a great health risk to the publicdue to increased industrial activity over recentyears. Current technologies used to remediatechromium contamination pose a threat to theenvironment and are costly. A more environ-mentally friendly and cost-effective alternative

Program TwoWednesday, May 24, 2000Metals Remediation

49

KINETICS OF CHRO-MATE REDUCTION BYCARBONATE GREENRUST

1Aaron Williams and 2Michelle Scherer,1,2Department of Civil & EnvironmentalEngineering, University of Iowa, 4016Seamans Center, Iowa City, IA 52242;Phone: (319) 335-5654, 1E-mail:[email protected]; 2E-mail: [email protected].

Recently, interest in abiotic redox reac-tions at iron oxide-water interfaces has in-creased significantly because of their impor-tance in natural attenuation processes andengineered remediation technologies. Specifi-cally, transformation of contaminants by greenrusts has emerged as a possible transformationpathway in both anoxic environmental systems(i.e., soils, sediments, and aquifers) andremediation technologies based on reductionby iron metal. Green rust minerals are mixed-valent iron hydroxides composed of positivelycharged octahedral sheets with interlayerscontaining anions such as chloride, sulfate, andcarbonate. The significance of transformationby green rusts in these systems, however, isstill unclear. The identification of green rustminerals in both systems has been limited dueto their rapid oxidation when removed fromreductomorphic or anoxic environments.Although synthesized green rusts have beenshown to reduce some hazardous chemicals(e.g., nitrite, selenium, and carbon tetrachlo-ride), the mechanisms and kinetics of thesereactions are not well known.

To this end, we are investigating thereduction of chromate by carbonate green rust.Carbonate green rust is synthesized in ananaerobic glove box, freeze dried, and charac-terized by x-ray diffraction (XRD) and


utilizes plant or bacterial matter as biosorbentsfor chromium remediation. Alfalfa is a pos-sible biosorbent because of its affinity fortrivalent and hexavalent chromium undersingle-metal and mixed-metal conditions. Inaddition, we have found that alfalfa reduceshexavalent chromium to trivalent chromiumwhich was characterized through x-ray absorp-tion near-edge structure (XANES) spectros-copy and extended x-ray absorption fine-structure (EXAFS) spectroscopy. However, aproblem commonly encountered in ion ex-change resins, as well as biosorbents likealfalfa, is the recovery of chromium afteradsorption. Some stripping agents providelow recoveries while others damage thebiosorbent which, in each case, affectsrecyclability of the biosorbent. In this studywe investigated the use of a wide array ofstripping agents such as dilute acids and basesunder batch experimental conditions. Also,flow studies using silica-immobilized biomasswere used to further investigate the ability ofvarious stripping agents to recover hexavalentand trivalent chromium. The results of theseexperiments will be presented.

Key words: XANES, EXAFS, alfalfa, chro-mium, recovery, metal binding, strippingagents

51

FORMATION AND STA-BILITY OF SUBSTITUTEDPYROMORPHITES: AMOLECULAR MODEL-ING APPROACH

1Abhijit Shevade and 2Shaoyi Jiang, 1Depart-ment of Chemical Engineering, Kansas StateUniversity, Manhattan, KS 66506; 2Depart-ment of Chemical Engineering, University ofWashington, Seattle, WA 98195; 1Phone:(785) 532-4322, 1E-mail: [email protected];2Phone: (206) 616-6509, 2E-mail:[email protected].

Soils contaminated with Pb pose signifi-cant risk to humans as well as terrestrial andaquatic ecosystems. The formation of pyro-morphites is an attractive alternative to immo-

bilized lead, but their formation and stability isaffected by possible substitutions (partial ortotal) by cations e.g., Cd2+, Zn2+, etc. for Pb2+

or anions, e.g., OH-, Br- etc. for Cl-in the soil.We report a molecular modeling approachbased on ab initio quantum mechanics prin-ciples to investigate the stability and formationof substituted pyromorphites by competingcation and anions. The stability of these metalphosphates is investigated based on the bindingenergy and by calculating the Gibbs freeenergy for these complex periodic crystalsusing molecular simulation tools. Geochemi-cal calculations are also performed usingMINTEQA2 to investigate the speciation andsolubilities of various substituted pyromorphi-tes under specified conditions similar to thosein experiments The impact of the presentwork will provide a fundamental understandingof the interactions of metals with a phospho-rous (P) source and address important ques-tions such as how metals compete for P insoils.

Key words: pyromorphite, substitution,stability, formation, molecular modeling


hydroxide as the Fe(II)/Fe(III) ratios change,and sequestration of previously soluble ions.

53

DETERMINING HISTORI-CAL MINING IMPACTS INTHE ROBINSON DIS-TRICT, ELY, NEVADA

1Andy Davis, G.G. Fennemore, and J.A.Anderson, Geomega, 2995 Baseline Road,Suite 202, Boulder, CO 80303; 1Phone: (303)938-8115, E-mail: [email protected].

Field data were collected and incorpo-rated within a coupled transport model tounderstand the incremental impact of historicwaste rock dumps and their associated seepson groundwater at the Robinson MiningDistrict. The rate of pyrite oxidation in wasterock dumps was predicted using the WROC-2D code calibrated to measured oxygen andtemperature profiles collected from waste rockdumps across the site.

The resulting seepage pond chemistry wasused as input to HYDRUS 2D to estimateinfiltration, coupled with PHREEQC to simu-late solute reactive transport to the water table.This flux was used as a source term in a steadystate, MODFLOW model using MT3D96 andPHREEQC to determine COC concentrationsat downgradient locations. A series of six3650-day stress periods (60 years from 1940 to2000) was run to simulate transport from theidentified historical source areas during leach-ing and draindown of the waste rock dumps.

Site topography, dump surface configura-tion, and anthropogenic leaching played anintegral role in determining the propensity forleachate to emanate from the base of wasterock dumps. All dumps generating acid seepscoincided with historic operations that pro-moted percolation of ambient precipitationand/or sulfuric acid amendments through thewaste rock. Sumps that collected storm waterrunoff formed in the historic drainages upslopefrom these waste rock dumps.

Because of the complex structural geol-ogy and metamorphism in the Robinson Dis-

Program TwoWednesday, May 24, 2000Mine Waste Remediation andDrainage Treatment

52

THE RELEVANCE OFREDOX TO REMEDIATION

Andy Davis, Geomega, 2995 Baseline Road,Suite 202, Boulder, CO 80303; Phone: (303)938-8115, E-mail: [email protected].

Redox conditions represent an importantcontrol on the speciation of metals includingAs (III/V), Cr (III/VI), Sb (III/V), and Se (IV/VI) chemistry. Although the measurement andenvironmental geochemistry of these constitu-ents is well understood, application of thisknowledge in setting regulatory standards forsoils, groundwater, surface waters, and sedi-ments is rare. Hence, bulk chemistry is usuallyconsidered in setting standards rather thanevaluating the ameliorating effect of metalvalence on toxicity and mobility. Given theescalating costs of environmental restitution, itis critical that reasonable options, including theinfluence of valence, be considered in settingrealistic, risk-based cleanup goals.

This paper provides examples of thevalue of understanding redox conditions andspecies in the environment. For example, themitigating influence of precipitation reactionsin sediments is demonstrated through sulfidesprecipitation and encapsulation of metals in abiologically active system in Richmond, Cali-fornia. Arsenic is less bioavailable in theAs(III) form in mine wastes due to sparingdissolution of these less soluble forms in theshort GI tract residence times. In addition,novel approaches to constrain metal solubilityby modifying the valence state are realisticgoals. For example, the solubility of Cr(III) inacid groundwaters can be reduced by carefulpH control while remediation of acid pit lakescan be affected by modification of the pH withconcomitant precipitation of amorphous ferric


trict and the depths to the regional aquifer,there have been no impacts from historic mineoperations to the deep carbonate aquiferswithin the Robinson Mining District. Laterally,groundwater flow from the mine area into theadjoining hydrogeologic provinces is minimaldue to numerous hydraulically impeding faultsand low conductivity rocks.

Solute groundwater transport simulationsdemonstrated that even sparingly reactivesolutes, such as sulfate, have not migratedmore than 1600 feet laterally from the InteraPond area, nor deeper than 5,400 feet amslwithin the area of investigation. Thus, anthro-pogenic surface sources have not contributedto degradation of deeper potable watersbeneath the mine site.

54

SUBSURFACE FLOWTREATMENT SYSTEMFOR MINE DRAINAGE

1,3T.M. Harris, 2V. Orrostietai, 2W.A. Roschet,and 3G. Rodolph, 1Departments of Chemistryand Biochemistry, University of Tulsa, Tulsa,OK 74104; 2Biological Sciences, University ofTulsa, Tulsa, OK 74104; 3Chemical Engineer-ing, University of Tulsa, Tulsa, OK 74104;1Phone: (918) 631-3090, 1E-mail: [email protected].

Mine drainage occurs when mines be-come flooded with groundwater and the watercomes in contact with sulfide minerals (e.g.pyrite, FeS

2). The sulfur in these minerals is

oxidized to sulfate ion, resulting in solubiliza-tion of the metals (primarily iron) and acidifi-cation of the water. Several groups have hadsome success treating mine drainage withsubsurface flow (SSF) passive treatmentsystems. In these systems, sulfate-reducingbacteria (SRB) convert the sulfate ion tosulfide, which in turn precipitates the metalsand/or scavenges hydrogen ion. A new SSFtreatment system design featuring horizontalflow has been developed in the present study.This system features a gravel layer, for en-

hanced fluid flow, overlain by a thick layer oforganic matter, which provides a suitableenvironment for the SRB. The performanceadvantages of this design demonstrated inlaboratory experiments will be presented. Inaddition, experiments with this system haveindicated that the SRB are not the only type ofmicroorganism that must be considered in SSFtreatment systems; fermentative heterotrophsmust be present and active in order to convertbiomass into the simple organic substratesutilized by the SRB.

Key words: mine drainage, sulfate-reducingbacteria, subsurface flow, passive treatmentsystem, constructed wetland

55

SILICA MICRO ENCAPSU-LATION: ARD TREAT-MENT AND BEYOND

Paul Mitchell and Amy Anderson, KleanEarth Environmental Company, 19023 36thAve. W., Suite E, Lynnwood, WA 98036;Phone: (425) 778-7165, Email:[email protected].

Klean Earth Environmental Companydeveloped the silica micro encapsulation(SME) technology to treat metals in water andsoil. Unlike conventional neutralization/precipitation methods, SME encapsulates thecontaminants in a permanent silica matrixresistant to degradation under even extremeenvironmental conditions. Encapsulatedmetals are effectively immobilized, minimizingthe potential for environmental contaminationand impacts on human or ecosystem health.SME is a very robust technology and has cost-effectively treated heavy metals (such aschromium, copper, lead, mercury, and zinc),metalloids (such as arsenic), and radionuclides(such as uranium). It can be applied to surfaceand groundwaters, wastewaters, sediments,sludges, soils, mine tailings, and other complexmedia. In addition to the control of metals,SME chemicals have been shown to reducedissolved solids (such as sulfates) and to


degrade or destroy hydrocarbons (such asgasoline and fuel oil) and other organic chemi-cals through a high-energy oxidation process.The most common SME application to datehas been in the treatment of acid rock drainage(ARD) from abandoned and operationalmining and quarrying sites. A wide range ofpilot- and field-scale projects, alongsidecommercial contracts, have demonstrated thatit provides better, faster, and cheaper treatmentthan liming and other conventional methods.However, over the past year SME has beenapplied to a much wider range of metal con-tamination issues. This paper briefly describesthe theory and practice of the SME technologyand its applications and then focuses on recentARD and non-ARD applications, including:

♦ Treatment of metal plating and otherindustrial wastewaters

♦ Treatment of storm water♦ Treatment of landfill leachate♦ Polishing of municipal and industrial

water supplies♦ Recovery of resources from metals-rich

waters♦ Onsite remediation of contaminated

soil♦ Stabilization of sediments♦ Stabilization of industrial and municipal

sludges♦ Silica coating to prevent or control

future acid generation♦ Combined-metals encapsulation and

hydrocarbon oxidation

Key words: metals, silica, encapsulation,stabilization, treatment

Program ThreeWednesday, May 24, 2000Containment

56

BIOCLOGGING OF CLAYLINERS

Lakshmi Reddi, and Hugo Davalos, Depart-ment of Civil Engineering, Kansas StateUniversity, Manhattan, KS 66506; Phone:(785) 532-1586, Fax: (785) 532-7717, E-mail: [email protected].

It is common practice to use compactedclays as liners for waste containment facilitiessuch as animal waste lagoons. The integrity ofsuch waste containment systems depends to alarge extent on mass transport and transfercharacteristics of the clay liners. In this paper,results from an experimental study are re-ported addressing the permeability changes ofcompacted clay samples permeated with cattlewaste and influents containing known bacterialcultures. The experiments were conductedusing Plexiglas columns similar to compactionpermeameters. Pore-size distributions of thesamples were determined using mercuryporosimetry before and after permeation withinfluents. In an attempt to explain the time-dependent changes in the permeability as aresult of bioclogging, the pore-size distribu-tions were used in the Kozeny hydraulic radiusmodel and the permeabilities were estimated.In spite of the large-pore development inpermeated samples (perhaps due to cracking ofthe samples), the permeabilities at the end of3-month long permeation were about the sameas or lower than the initial permeabilities. Acomparison of the experimental observationswith estimates using the hydraulic radiusmodel reveals that gas accumulation in thelarge pores could be the likely reason (and notthe biomass growth) for the time-dependentreductions in permeability. It was concludedthat permeability reductions as a result of


bioclogging may not occur during the time ittakes for breakthrough of certain importantcontaminants in the influent. Thus it may notbe a conservative design approach to accountfor bioclogging reductions in the designedpermeabilities of clay liners.

Key words: bioclogging, compacted clayliners, permeability, animal waste lagoons

57

EFFECTS OF SUBSTRATECONCENTRATION ONPERMEABILITY REDUC-TION AND TCE DEGRA-DATION IN A MULTI-SPECIES BIOFILM

1John Komlos, 1Al Cunningham, and 2RobertSharp, 1Center for Biofilm Engineering,Montana State University, 366 EPS Building,Bozeman, MT 59717-3980; 2EnvironmentalEngineering Department, Leo Hall, Manhat-tan College, Riverdale, NY 10471; 1Phone:(406) 994-4770; 2Phone: (718) 862-7169.

Recalcitrant compounds, such as trichlo-roethylene (TCE), show little natural attenua-tion. The development of a biologicallyproduced subsurface barrier capable of degrad-ing TCE while reducing its migration couldresult in a significant advancement inbioaugmentation technology. Burkholderiacepacia PR1-pTOM31c has the ability toaerobically degrade TCE but is unable to forma biofilm capable of significantly reducingporous media permeability. This researchexamined the effects of combining B. cepaciawith Klebsiella oxytoca, a thick biofilm-producing bacteria, in order to create a reac-tive/reduced-permeability biobarrier.

The research indicated that speciesgrowth rate was not an adequate predictor ofwhich microorganism would out-compete theother in a biofilm. Rather, substrate concentra-tion was a dominant variable in controlling thepopulation distribution of the two organisms.At high substrate concentrations, K. oxytocawas the dominant organism in a dual-speciesbiofilm. At lower substrate concentrations,

there was a shift in the population distributionwith B. cepacia being the dominant microor-ganism. Varying substrate concentrationenabled us to manipulate the populationdistribution in this dual-species biofilm. Thisconcept was expanded to a constant head,porous media reactor. The results from theporous media reactor showed a similar shift inpopulation with change in substrate concentra-tion. K. oxytoca provided similar permeabilityreduction at high and low substrate concentra-tions. B. cepacia achieved greater populationdensity, and higher TCE-degrading potential,at the lower substrate level. Thus, similarreduction in hydraulic conductivity coupledwith a significantly higher TCE-degradingpotential at the lower substrate level wasobserved.

Key words: biofilm, biobarrier, multi-species,subsurface, trichloroethylene

58

MODELING OF SUBSUR-FACE BIOBARRIER FOR-MATION

1Benito Chen and 2Hristo Kojouharov, 1De-partment of Mathematics, University ofWyoming; 2Department of Mathematics,Arizona State University; 1Phone: (307) 766-4221, 1E-mail: [email protected]; 2Phone:(480) 965-3745, 2E-mail:[email protected].

Biofilm-forming microbes can formbiobarriers to inhibit contaminant migration ingroundwater. Also subsurface biofilms havethe potential for biotransformation of organiccontaminants to less harmful forms, therebyproviding an in situ method for treatment ofcontaminated groundwater supplies. Wepresent a mathematical and numerical model todescribe the population distribution, growth,and movement of bacteria in porous media.The model is based on the convection-disper-sion equation with nonlinear reaction terms.


Accurate numerical simulations are crucial tothe development of contaminant remediationstrategies. We use the nonstandard numericalapproach that is based on nonlocal treatmentof nonlinear reactions and modified character-istic derivatives. It leads to significant, qualita-tive improvements in the behavior of thenumerical solution. Numerical results for asimple biobarrier formation model are pre-sented to demonstrate the performance of theproposed new method. We will show compari-sons with experimental results obtained fromthe Montana State’s Center for Biofilm Engi-neering.

Key words: biobarriers, models, biofilms,simulations

59

SUPERCRITICAL FLUIDTECHNOLOGY FORREMEDIATION OF PCB/PAH-CONTAMINATED SOILS/SEDIMENTS

1L.L. Tavlarides, W. Zhou, and G. Anitescu,Department of Chemical Engineering andMaterials Science, Syracuse University,Syracuse, NY; 1Phone: (315) 443-1883, 1E-mail: [email protected].

A two-stage technology employing greensolvents such as supercritical CO

2 (SC-CO

2)

and supercritical water (SCW) for the extrac-tion and destruction of polychlorinated biphe-nyls (PCBs)/polynuclear aromatic hydrocar-bons (PAHs) from contaminated soils/sedi-ments is proposed. Results of our laboratoryand bench-scale investigations indicate thatSC-CO

2 modified with 5% methanol is an

effective solvent and conditions have beendefined to achieve sub 5 ppm in 45-60 minutesfor 99.8% removal. Comprehensive data on

PCB/PAH solubilities in SC-CO2/MeOH,

partition equilibria and desorption provide asolid basis to develop models regarding theextraction of these pollutants from solidmatrices. Further, the supercritical wateroxidation (SCWO) stage, coupled to theextraction process with three possible configu-rations, would provide clean effluent materials.The ultimate products of the proposed tech-nology are mainly clean soil/sediments andinorganic species such as H

2O, CO

2 and small

amounts of chlorides. Our SCWO studiesindicate that 5245 ppm Aroclor 1248 in metha-nol-simulated soil extract solutions can beoxidized to 99.95% conversion in less than oneminute at 550°C. An economic analysis basedon a conceptual design of the process indicatesthat the expected costs of $198-318 m3 of soilprocessed is economically competitive.

Key words: PCB, remediation, supercriticalextraction/oxidation

60

COMBINED FENTON’SOXIDATION AND BIO-DEGRADATION FOR THETREATMENT OF PCP-CONTAMINATED WATER

1Julio Zimbron and 2Kenneth Reardon, 1,2De-partment of Chemical and Bioresource Engi-neering, Colorado State University, FortCollins, CO 80523-1370; 1Phone: (970) 491-1123, E-mail: [email protected];2Phone: (970) 491-6505, 2E-mail:[email protected].

Chlorinated compounds, often found inindustrial wastes such as wood treating andpaper pulp manufacturing waste, are a com-mon source of water contamination. Thesecompounds are intrinsically recalcitrant tobiodegradation, resulting in limited applica-tions of biodegradation to water contaminatedfrom this type of waste. A promising solutionto this problem is the combination of chemicaloxidation with biological degradation.

Combinations of chemical and biologicaldegradation processes can be more effectiveand cost-efficient than either chemical or

Program ThreeWednesday, May 24, 2000Remediation I


biological treatment alone for the treatment ofgroundwater, process wastewater, and drink-ing water. The goals of this research are (1) todevelop a mathematical model for the combi-nation of chemical oxidation using Fenton’sreagent (hydrogen peroxide and ferrous ion)and biological degradation of chlorinatedphenols, and (2) to use the model to optimizeoperating conditions and reactor configura-tions for the combined system.

This presentation includes new data onthe mechanisms and rates of Fenton’s reactionfor PCP in water, as well as new data on thebiodegradation rates of chemically oxidizedintermediates. The Fenton’s degradation rateof PCP was determined by the competitivekinetics method, and compared with theFenton’s degradation rates for otherchlorophenols by means of Hammett’s equa-tion, a group contribution method. It wasfound that these degradation rates were in-versely proportional to the degree of chlorina-tion of the phenolic ring.

A model aqueous waste consisting ofPCP has been treated with a sequential combi-nation of Fenton’s reagent (for chemicaloxidation) and a packed-bed bioreactor inocu-lated with activated sludge from a municipalwastewater treatment plant. The PCP concen-trations in the feed to the chemical reactor, theeffluent of the chemical reactor, and the efflu-ent of the bioreactor were determined. Inaddition, the amount of protein in the effluentfrom the bioreactor was measured to estimatethe extent of biodegradation of the waste. Ata residence time of 1.5 hr in the Fenton’sreactor, operating at molar dosage ratios ofH

2O

2/PCP of 3.0 and 7.7, 42% and 63% of the

PCP present in the feed was degraded, respec-tively. PCP was not biodegraded in the fol-lowing biodegradation stage at a residencetime of 5.5 hr. However, the extent of biodeg-radation achieved by the microbial populationon the Fenton’s pretreated, PCP-contaminatedwater was proportional to the extent of theprevious Fenton’s degradation of PCP.

Key words: mineralization, mixture-basedmodel, advanced oxidation process, biodegra-dation

61

PREDICTING GROUND-WATER CIRCULATIONWELL PERFORMANCE

1Jason Hellman, and 2Andrew Curtis Elmore,1URS Greiner Woodward Clyde, 101 South108th Avenue, Omaha, NE 68154; 2URSGreiner Woodward Cleyde, 10975 El Monte,Suite 100, Overland Park, KS 66211; 1Phone:(402) 334-8181, 1E-mail:[email protected]; 2Phone: (913)334-1154, 2E-mail:[email protected].

Groundwater circulation well (GCW)techniques are an innovative remedial technol-ogy that may effectively remediate contami-nated groundwater in areas where moretraditional technologies are unfavorable.Traditional pump and treat systems may beproblematic where concentrated hot spots ofcontamination are present, where aquiferdrawdown due to remedial activities is unac-ceptable, where surface discharge of treatedgroundwater is unwanted, or where propertyacquisition is challenging. The vertical compo-nent of groundwater flow induced by GCWsystems presents a new challenge to practitio-ners evaluating thc potential performance ofGCW systems. Modifications were made totwo familiar pump and treat analysis tools,capture-zone type curves and MODFLOWnumerical groundwater flow modeling, topredict site-specific effectiveness of GCWtechnologies. These techniques were used topredict the GCW treatment area dimensions.This included the capture zone, recharge zone,and circulation cell diameter. Additionally,GCW design parameters, including GCWspacing, screen length, screen placement, andcirculation flowrate, were determined. Thestate of the practice is to use these predictivetools to design an instrumentation scheme that


can effectively evaluate the performance ofGCW systems during full-scale pilot testing.

Key words: groundwater circulation well(GCW), capture zone, recharge zone, circula-tion cell, MODFLOW

62

ENHANCED IN SITUBIOREMEDIATION OFCHLORINATED SOL-VENTS WITH THEBIOLUXING SYSTEM

1Theodore Meiggs, 1C. Alvin Yorke, 1JeffreyFleischman, and 2William Mahaffey, 1Fore-most Solutions, Inc. 350 Indiana Street, Suite415, Golden, CO 80401; 2Pelorus EnBiotechCorporation, 3528 Evergreen Pkwy, Ever-green, CO 80439; 1Phone: (303 271-9114,1E-mail: [email protected]; 2Phone:(303) 670-2875, 2E-mail:[email protected].

BioLuxing is a remediation technologythat utilizes jetting and hydraulic fracturingtechniques to create large porous networkswithin contaminated soil or groundwaterzones. These subsurface networks can beinstalled at great depths and in a variety of soiltypes. They make effective distribution sys-tems for the repeated delivery of contaminate-degrading bacteria, nutrients, and electronacceptors or electron donors to stimulatebiodegradation processes in the contaminatedzones. This paper will discuss the applicationof this technology for enhanced bioremediationof chlorinated solvents in both aerobic andanaerobic environments.

Key words: chlorinated solvents, BioLuxing,hydraulic fracturing

63

AIR-SPARGINGREMEDIATION: A STUDYON HETEROGENEITYAND AIR-MOBILITYREDUCTION

1Shoeleh Di Julio and 2Andrew Drucker,1California State University, Northridge,Northridge, CA 91330; 1Phone: (818) 667-2496, 1E-mail: [email protected];2Phone: (805) 982-4847, 2E-mail:[email protected].

Contaminated groundwater is a wide-spread problem often requiring innovativetechnology to remediate. The use of one suchtechnology, in situ air-sparging (Johnson, et.al., 93, Ahfield et. al., and 1994, Hinchee,1994), has lead to an increased interest inunderstanding the mass transfer process. Thepurpose of this paper is to present the labora-tory results of air-sparging models. Initial testsused very fine porous media (glass beadspacked column) to represent relatively homo-geneous soil samples. Subsequent testingemployed budded core samples taken from asite of interest to represent more realistic,heterogeneous samples. 1,1,1 Trichloroethane(TCA) was used as the dissolved contaminantto represent BTE/gasoline contamination;however, results obtained here can be appliedto any NAPI-dissolved phase. A technique toimprove the contaminant removal based onfoam injection is presented. The laboratoryresults are compared with the numerical modelprediction of an advection-diffusion, air-spargesimulation model based on the mathematicalmodel developed by Wilson, et al. (1994).Sensitivity analysis of the numerical modelprovides the range of some key parametersused to screen/evaluate air sparging as theremediation method for a given contaminatedsite of interest. The numerical model devel-oped here simulates air flow as it travelsthrough a saturated soil column contaminatedwith dissolved volatile organic compounds(VOCs). Eventual scaleup of the model to anactual site application can be justified by thefavorable results presented in this paper.

Program ThreeWednesday, May 24, 2000Remediation II


Key words: remediation, air sparging, NAPL,foam

64

MONITORED NATURALATTENUATION OF CHLO-RINATED COMPOUNDS

Timothy Cox, Rocky Mountain Consultants,Inc., 825 Delaware Ave, Suite 500, Longmont,CO 80501; Phone: (303) 665-6283, E-mail:[email protected].

Natural attenuation was evaluated as apossible corrective action for a plume ofvolatile organic compounds (VOCs) migratingfrom a closed landfill in Littleton, Colorado.In January 1995, a corrective action wasimplemented at the request of the state toprevent the further migration of VOCs, whichincluded installation of a groundwater inter-ceptor trench and collection sump (recoverysystem) immediately downgradient of thelandfill boundary. Performance monitoring ofthe recovery system has been conducted since1995, and decreasing concentrations of parentconcentrations and production of daughterproducts were observed, suggesting thatnatural attenuation processes were occurring.A supplemental evaluation was conducted inJanuary 1999 to determine if the groundwatersystem was capable of naturally attenuatingVOCs, such that the recovery system could beshut down. The evaluation was conductedusing technical guidelines for demonstratingnatural attenuation of chlorinated solventsprepared by the U.S. Air Force Center forEnvironmental Excellence. The guidelines callfor evidence of 1) reduction in contaminantconcentrations, 2) loss of contaminant mass,and 3) geochemical data supporting biodegra-dation. A decrease in contaminant concentra-tions had already been demonstrated from thefour years of monitoring data; however,collection of additional geochemical data andassessment of the reduction of contaminantmass were required. The first component ofthe supplemental evaluation included collec-

tion of site-specific geochemical data frommonitoring wells, including measurements ofdissolved oxygen, reduction/oxidation poten-tial (redox), nitrate, iron (II), sulfate, andsulfite. Some of the compounds may serve aselectron donors or acceptors, and dependingon their concentrations, may either facilitate orimpede reductive dechlorination. Dissolvedoxygen and redox were measured to determineif the groundwater system was reducing,thereby favoring reductive dechlorination.Additionally, end-member compounds wereanalyzed including ethane, ethene, methane,and chloreothane, where the presence of thesecompounds would support complete reductivedechlorination. The second component of theevaluation was to calculate the reduction ofmass. The calculation was made by comparingisocontour maps of VOC concentrationsmeasured prior to start-up of the recoverysystem to recent concentrations measured inJanuary 1999. A particular concern at the sitewas the rising groundwater levels due toincreased water use of residential developmentwithin the watershed. Therefore, the effect ofrising water levels had to be considered toidentify if the mass reduction was simply dueto dilution or due to actual biodegradationprocesses. Results of the evaluation demon-strated that the groundwater system was underreducing conditions and geochemical condi-tions support reductive dechlorination. End-member compounds were detected whichfurther demonstrated that dechlorination wasoccurring. Also, the mass of VOCs had beenreduced even after accounting for dilution.Results of the evaluation were presented tostate regulators together with a plan for futuremonitoring to assure that natural attenuation isoccurring. The recovery system was shutdown in June 1999 and subsequent monitoringhas shown that VOC concentrations continueto decrease.

Key words: attenuation, groundwater, VOCs,monitoring


66

NANOSCALE METALOXIDES USED ASDEHYDROHALOGENATIONCATALYSTS

1Ryan Richards, 2Ilya Mishakov, 3VladimirChesnokov, 4Alexander Volodin, and 5KennethKlabunde, 1,5Department of Chemistry, WillardHall, Kansas State University, Manhattan, KS66502; 2,3,4Boreskov Institute of Catalysis,Prospekt Lavrentieva 5, Novosibirsk 630090,Russia; 1Phone: (785) 532-6849, 1E-mail:[email protected]; 2E-mail: [email protected]; 4E-mail: volodin@catalysis nsk su; 5E-mail:[email protected].

The unique properties and chemistry ofmetal oxide nanoparticles including character-ization of Lewis acid and base sites usingelectron paramagnetic resonance (EPR),structures using transmission electron micros-copy (TEM), and catalytic properties havebeen investigated. These metal oxidenanoparticles have been found to demonstratehigh activity and selectivity for the dehydro-chlorination of 1-chlorobutane. The selectivitytowards dehydrochlorination to butylene ismuch higher for autoclave prepared (AP) MgOand CaO catalysts than Al

2O

3. This catalytic

activity has been found to increase uponconversion of the metal oxide catalyst tochloride. Experiments have been expanded inscope to investigate compressed metal oxidesamples, 1-bromobutane catalyticdehydrohalogenation, and surface area andpore structure analysis, as well as mechanisticstudies.

Key words: nanoparticles,dehydrohalogenation, catalysis, metal oxide

Program ThreeWednesday, May 24, 2000Nanotechnology Applications

65

NANOCRYSTALLINEADSORBENTS OF ACIDGASES

1Gavin Medine and 2Kenneth Klabunde, 1,2111Willard Hall, Kansas State University, Man-hattan, KS 66506; 1Phone: (785) 532-6829,1E-mail: [email protected]; 2Phone: (785)532-6849, 2E-mail: [email protected].

The intrinsic differences betweennanocrystalline MgO (AP-MgO), microcrystal-line MgO (CP-MgO), and commercial MgO(CP-MgO) in relation to morphology, reactiv-ity, and active sites were studied. Morphologi-cally the nanoparticles (AP-MgO) are uniqueand very different from the conventionalsamples (CP-MgO, CM-MgO).Nanocrystalline MgO possesses more defects,edge and corner sites, higher surface area, andhigher index surfaces. Sulfur dioxide was usedas an absorbate due to its variety of possiblebonding geometries and for more practicalreasons for its involvement in producing acidrain.

Key words: nanocrystalline, sulfur dioxide,MgO


67

BIOCIDAL CAPABILITIESOF NANOPARTICLES

1John Klabunde, 1George Marchin, and2Kenneth Klabunde, 1Departments of Chemis-try and Biology, Kansas State University,Manhattan, KS 66506; 2111 Willard Hall,Kansas State University, Manhattan, KS66506; 1Phone: (785) 532-6829 or (785) 532-6635, 1E-mail: [email protected] [email protected]; 2Phone: (785) 532-6849.

The biocidal capabilities of autoclaved-prepared halogenated metal oxidenanoparticles were studied. Chlorinated MgO(AP-MgO-Cl

2), brominated MgO (AP-MgO-

Br2), iodinated MgO (AP-MgO-I

2), chlorinated

CaO (AP-CaO-Cl2), brominated CaO (AP-

CaO-Br2, and iodinated CaO (AP-CaO-I

2)

were allowed to contact Bacillus cereusspores. Times of exposure were varied. Theresults showed that the spores were disin-fected, and the efficiency of this processdepended on halogen loading and time ofcontact. Electron microscope pictures showedthat the spores were cleaved open. These andrelated results will be discussed.

Key words: nanoparticles, biocidal, haloge-nated, conventionally prepared, autoclavedprepared, magnesium oxide, calcium oxide,metal oxide

lewis acid catalysts such as AlCl3, ZnCl

2, and

BF3 which are being applied in Friedal-Crafts

alkylation reactions. Similarly there has beenan interest for developing newer and moreselective ways for chlorination of hydrocar-bons which is presently done at high tempera-tures or photocatalytic methods, or by employ-ing HCl/ZnCl

2 as reagents. Nanostructured

MgO and CaO prepared by an aerogel methodare highly reactive having 4-7 nm crystallinesize with high surface area. NanocrystallineMgO, when exposed to Cl

2 gas at atmospheric

pressure and room temperature, formed anextremely reactive MgO-Cl

2 adduct and has

been used as a catalyst in the chlorination ofhydrocarbons. The chlorination of hydrocar-bons was performed in a specially designedpulse reactor to handle the corrosive Cl

2 gas,

and this method overcomes the difficulties inthe high-temperature/photocatalytic pathwaysand in the use of HCI/ ZnCl

2 reagents. The

results report an unique application ofnanocrystalline metal oxides as catalysts inchemical processes to find remedies for envi-ronmental problems.

Key words: nanostructure, catalyst, chlorina-tion, selectivity, magnesium oxide

NANOSTRUCTUREDMETAL OXIDES ASCATALYSTS FOR ENVI-RONMENTALLY BENIGNCHEMICAL PROCESSES

1Ravichandra Mulukutla and 2KennethKlabunde, 1,2Department of Chemistry, KansasState University, Manhattan, KS 66506-3701;1Phone: (785) 532-6829, 1E-mail:[email protected]; 2Phone: (785) 532-6849, 2E-mail: [email protected].

68

There has been a growing concern todevelop environmentally viable chemicalprocesses by finding alternatives for the toxic


69

A NATIONWIDE FIELDTEST OFPHYTOREMEDIATIONFOR PETROLEUM CON-TAMINATED SOILS

1Peter Kulakow and 2Larry Erickson, 1Depart-ment of Agronomy, 2004 Throckmorton PlantSciences Center, Kansas State University,Manhattan, KS 66506; 2Center for HazardousSubstance Research, 101 Ward Hall, KansasState University, Manhattan, KS 66506;1Phone: (785) 532-7239, 1E-mail:[email protected]; 2Phone: (785) 532-4313,2E-mail: [email protected].

The EPA-sponsored Research Develop-ment Technology Forum (RTDF) forPhytoremediation, Total Petroleum Hydrocar-bon (TPH) Subgroup has developed a protocolfor a nationwide field test of phytoremediationof petroleum hydrocarbon-contaminated soils.Currently 11 sites are entered in the trial. Theexperimental protocol specifies three vegeta-tion treatments including a standard grass/legume mixture planted at all locations, alocally determined vegetation treatment usuallyincluding native species or trees, and anunvegetated control. Soils are to be sampledannually at two depths with the analysis of soilsamples performed at common laboratories.Petroleum hydrocarbon analysis includesdetermination of total petroleum hydrocarbonsby GC/FID, estimation of polycyclic aromatichydrocarbons, and estimation of biomarkersfor use in normalization of the data. Petro-leum hydrocarbon composition also will beassessed using the TPH Criteria WorkingGroup method to fractionate hydrocarbonsinto 13 aliphatic and aromatic fractions. Thestatus of the field sites will be summarizedalong with a summary of the experimentalprotocol and some of the issues addressed inearly phases of the trial.


70

PHYTOREMEDIATION OFPETROLEUM-CONTAMI-NATED SOIL

1G.J. Thoma, 1T.J. Gentry, 1L.J. Krutz, 1D.C.Wolf, 1C.A. Beyrouty, and 2C.M. Reynolds,1University of Arkansas, Plant Science 115,Fayetteville, AR 72701; 2USACRREL,Hanover, NH; 1Phone: (501) 575-5739, 1E-mail: [email protected].

Traditional techniques of remediatingpetroleum-contaminated soil can be expensiveand labor intensive. Phytoremediation is aneconomical alternative technology that couldbe used at many drilling rig sites. The goal ofphytoremediation is to enhance the biodegra-dation rate and to lower the contaminantconcentration to an acceptable level. Researchon phytoremediation is needed to defineappropriate plants to establish at the sites, thefertility levels to optimize plant growth andpetroleum degradation, and the benefits ofadding soil amendments. A greenhouseexperiment was conducted to evaluate germi-nation and growth of bermuda grass, rye grass,fescue, crabgrass, and alfalfa in a crude oil-contaminated soil. In addition to an un-amended control, broiler litter, inorganicfertilizer, paper mill sludge, and sawdustamendments were studied. Analysis of plantand amendment effects on phytoremediationwill increase our understanding of theremediation processes in oil-contaminatedsoils.

Key words: petroleum-contaminated soil,phytoremediation, contaminant concentrations

Program OneThursday, May 25, 2000Oilfield Production Remediation I


71

BIOSURFACTANT-PRO-DUCING BACTERIAFOUND IN CONTAMI-NATED AND NON-CON-TAMINATED SOILS

1Eleanor Jennings and 2Ralph Tanner, 1,2De-partment of Botany and Microbiology, Univer-sity of Oklahoma, 770 Van Vleet Oval,Norman, OK 73019; 1Phone: (405) 325-1647;1E-mail: [email protected]; 2E-mail:[email protected].

Microbially produced surfactants havebeen studied for use in the bioremediation ofhydrocarbons and microbially enhanced oilrecovery (MEOR). However, most of thesestudies involved only a small number of bacte-ria isolated in a laboratory and then taken backto an environment. Here, we examined soilsfrom two different hydrocarbon-impactedsites—one in northeastern Oklahoma and theother near Ft. Lupton, Colorado. Uncontami-nated soils from both of these sites wereexamined also. Biosurfactant-producingbacteria were found in numbers ranging from102 to 104, and neither site showed any signifi-cant difference between their uncontaminatedand contaminated soils. Aerobic heterotrophswere also enumerated and again no significantdifference was determined between soil condi-tions on either site. Identification of isolatedbacterial colonies showed that Pseudomonasand Bacillus species were the primarybiosurfactant-producing bacteria in these soils.Future work suggested by these results in-cludes an examination of additional hydrocar-bon-contaminated sites as well as artificialcontamination of the soil to see if the estab-lished trend continues.

Key words: biosurfactant, Bacillus,Pseudomonas

72

LEADHYPERACCUMULATIONBY SESBANIADRUMMONDII

1Robert Barlow, 1Natalie Bryant, 1JohnAndersland, and 2Shivendra Sahi, Departmentof Biology, Western Kentucky University, 1Big Red Way, Bowling Green, KY, 42101;1Phone: (270) 745-6012, 1E-mail:[email protected]; 2E-mail:[email protected].

Sesbania drummondii is a leguminousplant commonly found in the southeasternUnited States. Our studies have shown thatseedlings of Sesbania drummondii canhyperaccumulate lead (Pb) in a controlledhydroponic environment. The addition of achelating compound (EDTA) further increasesthe amount of Pb that a seedling can accumu-late. Pb-treated roots were analyzed withscanning and transmission electron micro-scopes equipped with energy dispersive X-rayspectrometers. Pb deposits were observed inconcentric rings around the stele, on subepi-dermal cortical cells, and on the surface of theepidermis. The lead appeared to be localizedwithin and on the cell wall. Phosphorus waspresent wherever lead was detected, suggest-ing that the lead precipitated as a lead phos-phate. The data gathered suggests that itwould be feasible to examine the Pb-accumu-lating capabilities of Sesbania drummondii in asoil environment.

Key words: phytoremediation, lead,hyperaccumulation, Sesbania, EDTA


Program OneThursday, May 25, 2000Oilfield Production Remediation II

73

REMEDIATION OFOILFIELD BRINE-IM-PACTED SOIL WITHSUBSURFACE DRAINAGE

1,2Thomas Harris, 1C. Dewan, 3K. Sullivent,2R. Yates, 3J.B. Tapp, and 2Kerry Sublette,1Departments of Chemistry and Biochemistry,University of Tulsa, Tulsa, OK 74104;2Chemical Engineering, University of Tulsa,Tulsa, OK 74104; 3Geosciences, University ofTulsa, Tulsa, OK 74104; 1Phone: (918) 631-3090, 1E-mail: [email protected].

The contamination of soil and waterresources with the brine that is typically co-produced with petroleum is arguably the mostserious environmental problem associated withthe exploration and production of petroleum.Soil that is contaminated with salt cannotsustain vegetation, and is thus susceptible toerosion. The consequent runoff of both topsoiland salt will also have an adverse effect ondownstream water resources. Subsurfacedrainage, coupled with deep-well injection ofthe collected leachate, is capable of decontami-nating brine-impacted soil while limitingsecondary contamination of nearby surfacewaters and freshwater aquifers. This technol-ogy is being demonstrated on a recent two-acre brine spill in the Tallgrass Prairie Pre-serve, Osage County Oklahoma. Results ofthe chemical analysis of the leachate and soilsamples collected over a two-year period willbe presented. The latter will be correlatedwith the extensive revegetation that has oc-curred through two growing seasons.

Key words: petroleum production, brine,brine-impacted soil, salinity, erosion, subsur-face drainage

74

PLANTING CROPS ONLAND SPREAD WITHTANK BOTTOMS: APOSSIBLE DISPOSALSOLUTION FOROILFIELDS

1Lorna Bradbury and 2Sandra Mark, 1Univer-sity of Regina, Regina Saskatchewan, P.O.Box 1040, Williston, ND 58802; 2PetroleumTechnology Transfer Council, Golden, Colo-rado, Colorado School of Mines, PTTC/Geology Department, 1500 Illinois Street,Golden, CO 80401; 1Phone: (701) 774-1319,1E-mail: [email protected]; 2Phone: (303)273-3107, 2E-mail:[email protected].

Tank bottoms from a Williston Basinoilfield were applied to test plots in whichcrops were subsequently planted. Naturallyoccurring microbes reduced the 6% totalpetroleum hydrocarbon (TPH) concentrationto 3.8% in a few months (a 37% reduction),but reduced it no further, possibly due to aninsufficient amount of nitrogen or water orboth. For the first three years of the study, the6% TPH test plot did not grow crops. It wasapparent that the high (6%) application rate ofthis high-paraffin oil seriously restricted theinfiltration of water into the soil; this is consid-ered to be the primary cause of crop failure,rather than toxicity of the tank bottoms. Aftermanure was applied in the fall of the third yearfollowing the tank bottoms application, cropswere successfully grown for the next twoseasons. In the fifth year, when the manurehad degraded, crop growth was again verypoor.

The second phase of the project studiedthe addition of straw and large amounts ofnitrogen and phosphate fertilizer to new testplots. A 0.6% TPH concentration was appliedto two test plots that had been previouslyplanted to spring wheat. Because there hadbeen no rain, the crop was poor, and there wasconcern that the application of oil plus tillingwould kill the crop. When it did rain later inthe summer, the seed left in the ground germi-nated and successfully produced a crop. The


addition of straw did not increase the chancesof crop growth; rather, it reduced the yield ofthe crop significantly, even with a higher rateof fertilizer application. The original 0.6%TPH concentration was reduced to 0.14% inone year, a 77% reduction, suggesting thatlower application rates may remediate faster, inaddition to allowing crops to grow.

This study suggests that application oflow concentrations of tank bottoms on agricul-tural land may be possible, but additionalresearch is needed to discover how to controlthe hydrophobic effects of this disposalmethod. The addition of manure (rather thanstraw) to land spread with tank bottomsappears to be favorable to plant growth byincreasing water infiltration and retention.

Key words: tank bottoms, oilfield wastedisposal, bioremediation, landfarming, hydro-phobic soils

75

CLOSURE OF AN EXPLO-RATION AND PRODUC-TION WASTE DISPOSALFACILITY

1Patrick Flynn, 2David Boyce, and 3ThomasMurphy, 1HS Resources, Inc., 1999 Broadway,Suite 3600, Denver, CO 80202; 1Phone: (303)296-3600; 2BP Amoco; 3LT Environmental,Inc., 4400 W 46th Ave., Denver, CO 80212;3Phone: (303) 433-9788, 3E-mail:[email protected] Background

The Weld County Waste Disposal, Inc.(WCWD) site was a 40-acre commercial wastedisposal facility originally permitted to receiveoil field brines and other petroleum-relatedliquid waste derived from oil and gas explora-tion and production (E&P) activities. Thefacility was built in the late 1970s and waspermanently closed in May 1995. Prior toclosure, liquids received were off-loaded into aconcrete receiving sump and transported viaaboveground pipe to a clay-lined impoundment(Pond C) where liquid hydrocarbons wereseparated from the produced water (brine) and

recycled. The water was transferred to asecond clay-lined impoundment (Pond D)where enhanced evaporation occurred as theprimary water disposal method.

The work was conducted in fulfillment ofthe requirements of a U.S. EnvironmentalProtection Agency (EPA) RCRA 7003 Admin-istrative Order (Orders) received by the ownerand the two largest local producers who hadpreviously used the facility. EPA developed theorders in response to environmental concernsas a result of the operational practices.

The structures containing the wasteproducts at the time of closure consisted of theconcrete receiving sump, eight ASTs, twoimpoundments, and a sludge drying bed. SinceAugust 1995, remedial measures were initiatedto eliminate the waste present. These mea-sures included the following:♦ Removal of over 647,000 bbls

(~27,000,000 gallons) of waterthrough the operation of an enhancedevaporation system. A residual 15,000bbls of heavy brine was injected into apermitted Class I well;

♦ Removal of 4,300 bbls (180,000 gals)of nonhazardous hydrocarbon liquidsand 20 yd3 of BS&W solids from theASTs and receiving sump. The wastewas disposed of at a commercialbiobed operation; and

♦ A sludge landfarming program of anestimated 20,000 yd3 of sludge withelevated hydrocarbon and salts.

Sludge Landfarm ProgramThe objectives of the program were to:

♦ Eliminate the potential for wildlife tobe exposed to the sludge;

♦ Reduce the accumulation of free waterin the pond from precipitation;

♦ Provide easy access to the pond forsubsurface characterization activities;

♦ Reduce the potential for verticalmigration of organic and inorganiccompounds;

♦ Provide oxygen, nutrients, and propersubstrate (wood chips and manure) to


initiate in-place biodegradation of thehydrocarbons; and

♦ Reduce the oily matrix to allow formore precise chemical characterizationof the sludge.

Establishment of Cleanup ObjectivesTo accomplish the on-site landfarming

project, chemical-specific cleanup objectiveswere established through the risk assessmentprocess that protects potential human recep-tors. The primary contaminants of concern—benzene, polynuclear aromatic hydrocarbons(PAHs), and arsenic—were evaluated. Theobjective was to establish what the maximumconcentration of these compounds could beafter the sludge treatment so as not to pose athreat based on potential future land usescenarios. This process was concurrent withthe implementation of the landfarming pro-gram.

The cleanup goals established werederived from risk-based concentrations(RBCs), background values, and soil-to-groundwater transfer concentrations using theSESOIL/AT123D fate and transport models.Cleanup goals based primarily on the moreconservative RBCs were established forbenzene (0.65 mg/kg) and the PAHs (chemicalspecific). Background values were used toestablish an arsenic cleanup goal of 22 mg/kg.

Implementation of Landfarming ProgramThe initial mixing of bulking material and

nutrients was conducted in May 1997 in PondC and in March 1998 in Pond D. An estimated4,125 yd3 of wood chips and 1,000 yd3 of cowmanure were added, increasing the sludgevolume by 25%. After conducting baselineanalyses, the initial nutrient addition consistedof six tons of urea and one ton ofmonoammonium phosphate. Tilling of theamended sludge occurred on average threetimes per month from June 1997 throughSeptember 1998. A second nutrient applica-tion occurred in June 1998 with 3.8 tons of

urea and 0.65 tons of monoammonium phos-phate added.Performance Results

Periodic performance monitoring of theamended sludge occurred. By September1998, the benzene concentration in the sludgewas non-detect at reporting limits below thecleanup goal of 0.65 mg/kg. The observedbenzene reduction since the inception of theaggressive tilling program is 99%. This isaccompanied by an overall reduction in totalhydrocarbons (TRPH) concentration of 84%.Although reporting limits of two PAHs ex-ceeded the established RBC cleanup goals,mitigation was achieved through the use of theSESOIL/AT123D models and closure designcriteria (i.e. soil cover). The models demon-strated that as a result of biodegradation in thegroundwater, the potential pathway was notcompleted. Arsenic concentrations did notexceed the established background values forthe area.

Site ClosurePermanent closure was achieved through

the elimination of the waste products andremoval of the remaining structures. TheASTs were dismantled and removed from thesite. The concrete sump was rubbleized andburied on site. Pond C containing theremediated sludge from both ponds wasbackfilled with berm material, a soil cover withdrainage controls constructed, and the siterevegetated. Final EPA approval is imminentand post-closure monitoring occurring todocument the success of the closure activities.

Key words: waste disposal, EPA,landfarming, fate and transport models,sludge


76

PIT LAKES--PAST,PRESENT, AND FUTURE

Andy Davis, Geomega, 2995 Baseline Road,Suite 202, Boulder, CO 80303; Phone: (303)938-8115, E-mail : [email protected].

Concern over pit lake chemistry is arecent phenomenon, initiated by the realizationthat the Berkeley Pit Lake would contain alarge reservoir of acidic, metal-rich surfacewater. However, over the past 10 years therehas been a rapid metamorphosis in pit lakeissues, the focus of this paper, includingpredictive analysis, model verification, ecologi-cal risk, closure, and the eventual use of thewater in pit lake storage in the 21st century.

Current predictive efforts have resulted ina general recognition that Carlin-type depositswill have adequate neutralizing capacity topreclude the formation of acidic pit lakes,while those hosted in metamorphic terrain arelikely to generate acidity with associated poorwater quality. Analog laboratory pit lakes area useful screening tool because no pit lakesinvestigated prior to refilling have yet formedto test model results.

It is likely that beneficial use issues willbecome important due to the huge volume ofwater in storage in pit lakes, the increasingrequirements for water, and the generally goodwater quality in many pit lakes. Other issuesinclude the technical efficacy of pit backfillingduring active mining, pit lake closure withrespect to the ultimate equilibrium chemistry,and the value of undertaking uncertain model-ing exercises. For example, a screening levelanalysis of water quantity and water qualityissues may suffice, with the funds for a com-prehensive study better utilized for activitiesthat directly benefit the community. Finally, it

is likely that more regulatory agencies willbecome involved in pit lakes in the U.S. andthat scrutiny abroad will intensify as environ-mental regulations become more stringent.

77

A BIOLOGICAL SURVEYOF THE BERKELEY PIT

Grant Mitman, Biology Department, MontanaTech of the University of Montana, Butte, MT59701; Phone: (406) 496-4617, E-mail:[email protected].

The Berkeley Pit Lake System is esti-mated to contain more than 30 billion gallonsof acidic, metal-laden water. Current investi-gations examine how the naturally occurringorganisms in the Berkeley Pit Lake Systemmight be stimulated by nutrient additions tobegin a self-purification process for aqueousenvironments impacted by acid mine drainage.The combined physiological processes havebeen observed to bioremediate aquatic minewaste environments. Consequently, if a minewaste site like the Berkeley Pit Lake System isproperly nutrified with nitrogen, phosphorous,or potassium (e.g. manure or sewage asinexpensive sources), this nutrification maycause a successional cascade of increaseddiversity and biomass that is coupled with anincrease in pH. A pH increase, in turn, maylead to a natural restoration process. Thus, ifsystems are to function correctly and to re-cover from pollution-induced perturbations,fundamental information both on the au-totrophic and heterotrophic components of themicrobial community is essential. Defining thebaseline community structure is the first steptoward understanding the interactions of thedifferent groups of extremeophiles and towardassessing any improvement in biodiversitywithin the biotic community.

Key words: acid mine drainage, Berkeley PitLake System, nutrification

Program TwoThursday, May 25, 2000Mine Pits and Pit Lakes I


78

CURRENT SEASONALLIMNOLOGY OF THEBERKELEY PIT LAKE

Jim Jonas, 9852 Independence Street,Westminster, CO 80021; Phone: (303) 421-7527, E-mail: [email protected].

The Berkeley Pit Lake was sampledduring two seasons, fall 1997 and spring 1998,from the surface to the bottom. Variousparameters were measured to determine whateffect the seasons had on the water chemistry.It appears that a seasonal turnover did occurbetween the fall and the spring sampling;however, the depth of mixing due to turnovercould not be established. Trends were ob-served which suggested the microbial activitywas altering the iron speciation at depth, andsubsequently masking the extent of mixing.Various trace metals were removed from thesurface water by either co-precipitation withschwertmannite or adsorption. Optical mi-croscopy, scanning electron microscopy, andgeochemical modeling were performed todetermine the composition of the precipitatesformed in the surface water. This work isbeing performed under the Mine Waste Tech-nology Program, funded by the U.S. Environ-mental Protection Agency (EPA) and jointlyadministered by the EPA and the U.S. Depart-ment of Energy, Contract Number DE-AC22-96EW96405.

DETERMINATION ANDCHARACTERIZATION OFORGANIC CARBON INTHE WATER AND SEDI-MENT OF THE BERKE-LEY PIT LAKE, BUTTEMONTANA

791Douglas Cameron and Margery Willett,Chemistry and Geochemistry Department,Montana Tech of the University of Montana,1300 West Park Street, Butte, MT 59701;1Phone: (406) 496-4247, 1E-mail:[email protected].

Past work has focused on the inorganicchemistry of the Berkeley Pit Lake; however,

recent work has shown that the water in thispit lake also contains organic carbon at a levelcomparable to the infiltrating groundwater (2-3 ppm). Depth profiles of the organic carbonwere obtained during the fall of 1997 and thespring of 1998. The results from these previ-ous studies will be compared to those obtainedfrom a fall 1999 sampling. The organic carbonprofile, from the previous studies, shows somecorrelation with the iron concentration and theiron (II)/iron (III) ratios in the pit lake. Thepossible effect of organic carbon on the ironchemistry in the pit lake will be discussed.Preliminary analyses have indicated that theorganic carbon content in sediments from theBerkeley Pit Lake are 100 times greater thanthat found in the overlying water. The pres-ence of this much organic carbon could have asignificant impact on the redox potential of thesediment and hence mineral formation. Or-ganic carbon depth profiles from two coreswill be presented and a comparison will bemade with iron and sulfur speciation in thesediment cores. The analysis of organiccarbon by nondispersive infrared absorptionspectroscopy in acid mine drainage waters iscomplicated by the high concentration ofsulfate and apparently the oxidation state ofiron. The reason for this sulfate interferencewill be shown and methods to correct for thisinterference will be discussed.

Key words: organic carbon, pit lake, redoxpotential


Program TwoThursday, May 25, 2000Mine Pits and Pit Lakes II

80

ALGALBIOREMEDIATION OFTHE BERKELEY PITLAKE

Grant Mitman, Department of BiologicalSciences, Montana Tech of the University ofMT, 1300 West Park Street, Butte, Montana59701; Phone: (406) 496-4617, E-mail:[email protected].

Ongoing research is unraveling theintricacies of the microbial ecology of theBerkeley Pit Lake System, with ever increasinginformation becoming available regarding thediversity of algae, protistans, fungi, and bacte-ria that inhabit this mine waste site. Definingthe baseline community structure has been thefirst step not only toward understanding theinteractions of the different groups of organ-isms, and also toward assessing any improve-ment in biodiversity within the biotic commu-nity. Now that this first step has begun, someof these extremophiles, specifically algae, thathave been isolated from the Berkeley PitlakeSystem are being used as a potential solutionfor bioremediation. The specific objectives ofthis research are fivefold: 1) To evaluate thebioremediative potential of our four mostrapidly growing species: (Chromulinafreiburgensis Dofl., Chlorella ellipsoideaGerneck, Chlorella vulgaris Beyerinck andChlamydomonas acidophilla Negoro) inBerkeley Pit Lake System water with theadditions of NaNO

3 and NaPO

4 by using an

experimental matrix. This matrix will be usedto estimate the minimum nutrient concentra-tions that would be necessary to achieve themaximum growth of algae and maximumbioremediation of the Berkeley Pit LakeSystem. 2) To determine which combinationof nutrients will stimulate growth of the bestbioremediator of our four isolated species in

natural Berkeley Pit Lake System waters. Inother words, what nutrient combination willgive the best bioremediator a competitive edgeover the other species. If time permits, differ-ent species may be grown in combination todetermine if there are synergistic effects(protocooperation) between species. 3) Todetermine a temperature profile for these fourspecies in order to determine their optimalgrowth temperature in Berkeley Pit LakeSystem water. 4) To continue to isolateorganisms from the Berkeley Pit Lake Systemand determine their bioremediative potential.5) Monitor algal and bacterial counts from aprofile of Pit Lake System waters. The resultsto date will be presented for this conference.

81

AN INVESTIGATION INTOTHE EFFECTS OF OR-GANIC AMENDMENTSON BERKELEY PIT LAKEWATER QUALITY UNDERVARIOUS ENVIRONMEN-TAL CONDITIONS

1Douglas Cameron and Margery Willett,Chemistry and Geochemistry Department,Montana Tech of the University of Montana,Butte, MT 59701; 1Phone: (406) 496-4247,1E-mail: [email protected].

Wetland studies to ameliorate acid minedrainage have shown 10-80% metal removalby sorption to insoluble or slightly solubleorganic matter. These works have also dem-onstrated decreases in the aqueous Eh valuesresulting from organic oxidation, increases inpH due to chemical reaction of the organicmatter, and the organic matter acting as acarbon source for sulfate-reducing bacteria(SRB). We have recently started investigationof the effects added organic amendments haveon the water quality of the Berkeley Pit Lake.The added organic carbon comes from sewagesludge, local grass clippings, local foliage, andsawdust. The sawdust, foliage, and grassrepresent precursors to natural humic materialand are often deposited in the local landfill.The sewage sludge is a readily available and


economic source of carbon. Each organicamendment is mixed separately with the waterin a 10% mass ratio, and the mixture is stirredcontinuously. The experimental matrix is suchthat a replicate of each mixture is exposed tothe following conditions: sunlight and air,sunlight and no oxygen, oxygen and no sun-light, or no oxygen and no sunlight. Smallfractions of the mixture will be removed as afunction of time and then filtered and analyzedto monitor the amount of dissolved metal ions,anions, and organic carbon. The pH of themixture will be monitored frequently, and thegases and volatile organic matter emitted fromthe mixture will be collected and analyzedperiodically. We will be reporting the resultsfrom these experiments.

82

MWTP-BERKELEYPIT LAKE RESEARCH

1Karl Burgher and Steve Anderson, MontanaTech of The University of Montana, 1300 WestPark Street, Butte, MT 59701; 1Phone:(406) 496-4410, 1E-mail:[email protected].

An interdisciplinary team of MontanaTech researchers, being funded by the MineWaste Technology Program (MWTP), hascurrently completed studying several aspectsof the Berkeley Pit Lake system to betterunderstand the system as a whole. The infor-mation obtained from the studies may be usedto predict future qualities of the water, toevaluate the natural rate of remediation, todetermine if partial in situ remediation may bepractical prior to expensive pump and treatremediation, and to predict water quality forsimilar bodies of water in the United States.The following research has been completed onthe Berkeley Pit Lake as part of this project:Biological Survey of Berkeley Pit Water;Sediment/Pore Water Characterization; Sul-fate-Reducing Bacteria; Surface OxidationReactions; and Organic Carbon. The projects

were funded through the Mine Waste Technol-ogy Program (MWTP). The MWTP is spon-sored by the EPA through the DOE, andimplemented by MSE Technology Applica-tions, Inc., in Butte, Montana. The underlyingtheme of all MWTP projects is remediationand/or control of current or future mine wasteproblems.

83

CLEANUP AT THE RAMPSITE IN DENVER, COLO-RADO

1Erna Waterman and 2Keith Anderson, 1Envi-ronmental Engineer/Project Manager USEPA, Region VIII, 999 18th Street, Suite 500,Denver, CO 80202-2466; 2EnvironmentalChemical Corporation; 1Phone: (303) 312-6762.

RAMP, a privately owned and operatedconsolidation and storage facility located inDenver, Colorado, was abandoned in 1994.RAMP processed low-level radioactive wastesand “mixed” wastes (wastes containing amixture of both radioactive waste and hazard-ous waste). The mixed waste that RAMPreceived contained solvents such astrichloroethane, tetrachloroethylene, methylenechloride, acetone, ethyl benzene, toluene, andmethanol. The U.S. Environmental ProtectionAgency responded to an emergency requestfrom the state of Colorado in August 1994.When EPA initiated the cleanup of the site,they identified approximately 5,500 drums ofunprocessed waste that needed removal. Inaddition to the technical difficulties in theremoval process, the site location requireddiligent effort in the public participationprocess due to the Environmental Justice “EJ”issues. The EPA addressed the removal action

Program ThreeThursday, May 25, 2000Multi-Stakeholder DecisionMaking I


at the site through consolidation of similarwaste streams, applying aggressive and cre-ative characterization techniques, on-sitestabilization, and numerous off-site treatmenttechnologies. The EPA completed the removalaction in 1999 and the site will not be placedon the National Priorities List (NPL).

84

APPORTIONING SLUDGEVOLUMES DISPOSED INA LANDFILL

1Andy Davis, P. DeCurnou, S. Helgen, and J.van Middlesworth, Geomega, 2995 BaselineRoad, Suite 202, Boulder, CO 80303; 1Phone:(303) 938-8115; 1E-mail:[email protected].

Sludges from a galvanizing operation anda tile manufacturer were sent to a Texaslandfill over a 17-year period. Closure wascomplicated by the estimated $14m cost, so atwo-part solution was proposed. First acheaper, less complicated (yet effective)closure plan received regulatory approvalwhile cost allocation proceeded in parallel.The closure plan was modified (with regula-tory approval) to avoid sludge stabilizationbecause the caustic soda and lime added toboth sludges resulted in immobilization of leadand zinc (the compounds of concern). Inaddition, the siliceous nature of the materialrendered further compaction prior to closureunnecessary. Waste apportionment used theend member materials to identify the mineral-ogic and chemical signatures of each that wereused to develop a three-component (Pb/Zn/Fe)mixing model. The proportions of the twowastes in 201 samples of mixed sludge in thelandfill were computed, the spatial distributionkriged, and the results summed to apportion-ment waste volumes between the two entities.The parties were able to settle when thelandfill closure costs were reduced to ~$4mand the mixing model showed that 93% of thewaste was from the tile manufacturer and 7%from the galvanizing operation.

85

A TRIBAL PERSPECTIVEON FEDERAL DEPART-MENTS’ AND AGENCIES’ENVIRONMENTAL JUS-TICE POLICY AND PRO-CEDURES: CASE STUD-IES FROMTHE DEPARTMENT OFENERGY

Jessica Alcorn, Council of Energy ResourceTribes, Department of Energy-Headquarters,Office of Intergovernmental and PublicAccountability, EM 11, Office of Environmen-tal Management, 1000 Independence Ave. SW,Rm. Lh-087,Washington, D.C. 20585; Phone:(202) 586-0798, E-mail:[email protected].

The environmental justice movement hadits beginnings in the growing perception thatenvironmental benefits and burdens have beeninequitably distributed--that the poor, thedisenfranchised, and minority communities arethe unwilling hosts to a disproportionatenumber of waste management and disposalfacilities and other environmentally undesirabledevelopments. President Clinton, in response,committed federal departments and agencies todevelop and implement environmental justicestrategies to address “disproportionately highand adverse human health or environmentaleffects of [their] programs, policies, andactivities on minority populations and low-income populations in the United States” whenhe signed Executive Order 12898 in February1994. However, casting environmental justicein distributive justice terms has not provenvery effective in addressing the communityempowerment prong of the environmentaljustice movement’s goals. The distributivejustice paradigm leads federal agencies toadopt a two-step approach to environmentaljustice: agencies first determine whether theiractivities will have impacts on “environmentaljustice communities” and second, determinewhether such impacts on such communities aredisproportionately high.

American Indian tribes have a growingconcern about the interpretation federal de-partments and agencies have taken for envi-


ronmental justice in relation to tribes. Execu-tive Order 12898 and the subsequent Councilof Environmental Quality environmental justiceguidance have defined tribes as “Native Ameri-can communities” to be included as a minoritygroup. This definition does not recognizetribes’ sovereign nation-state status, noridentifies the federal trust responsibility totribes. The author suggests that environmentalinjustice is not fundamentally about distribu-tions of benefits and burdens or the definitionof minority communities and disproportionateimpacts, but is, instead, about the inability ofcommunity institutions to participate in thebroad range of decisions that determine if,where, when, and under what conditionsundesirable land uses and development will beapproved. The author maintains that the finalreport of the U.S. Environmental Protection’sFederal Facilities Environmental RestorationDialogue Committee suggest that more thanprocedural justice or participation in decisionmaking is required. This paper sets out acapacity-building model of environmentaljustice based on the recommendation of theFFERDC report and the approach taken by theDepartment of Energy to implement its IndianPolicy.

Key words: environmental justice, AmericanIndian tribes, DOE

86

COMMUNITY SKEPTI-CISM NEEDED IN SUC-CESS FORMULA

Stuart Hill, Community Involvement Coordi-nator (P-l9J), U. S. Environmental ProtectionAgency, 77 West Jackson Boulevard, Chicago,IL 60604; Phone: (312) 886-0689; E-mail:[email protected].

Program ThreeThursday, May 25, 2000Multi-Stakeholder DecisionMaking II

A healthy dose of skepticism is one of themany legacies left for a community in anenvironmental melodrama that became a moviescript.

That skepticism lay dormant, like theDDT in the river which bisected the Michigantown of St. Louis, until the EnvironmentalProtection Agency announced plans to changeits remedial plans from natural attenuation todredging. Latent emotions exploded from thecommunity which feared the return of televi-sion cameras, which watched its principleemployer disappear overnight decades before,and which was excluded from decisions influ-encing its future.

Armed with a healthy respect for theskepticism the community so openly ex-pressed, the U.S. EPA encouraged its criticsthrough the use of several proven tools in itsCommunity Involvement process at Superfundsites. To date, the results are favorable andrange from doubt to enthusiasm—expressed intaking brownfield initatives. Other, moresubtle, changes have occurred in the commu-nity with Superfund activities serving as thecatalyst. These include a community riverbankcleanup and a fishing derby, now annualevents, in a body of water ignored by residentsfor the contamination it contained.

In only two short years since Region 5began remediation of the Pine River in centralMichigan, the town has made a remarkable


transition from the quaint, unassuming smalltown depicted in the 1981 movie “BitterHarvest,” starring Ron Howard. Once thecenter of a crisis calling for the slaughter ofdairy herds—the mid-1970’s event which madethe city synonymous with chemical contamina-tion—the town now views its brownfields asdevelopment opportunities. Yet, the skepticsremain and they are still encouraged.

The long-standing EPA tool of a Commu-nity Advisory Group (CAG) was first devel-oped to address doubts. The CommunityAdvisory Group quickly became one of themore active and aggressive in Region 5 withclose to 40 people attending monthly meetings.When the meetings became so heavily indoctri-nated with technical matters that non-technicalmembers lost interest, a Technical AdvisoryGroup (TAG) was formed. The two groupsbecame the general and the specific doubters,respectively.

Community involvement methods weredevised to address the issues of both groups.But what about others? How about businessand youth interests? How could they beserved? Simple answers provided in a brieforal presentation.

87

COMMUNITY RELATIONSISSUES RELATED TORESIDENTIAL SITE IN-VESTIGATIONS ANDCLEANUPS

1Lisa Sigler, and 2David Folkes, 1Sigler Com-munications, Inc, 1324 S. University Blvd,Denver, CO 80210; 2EnviroGroup Limited,7208 S. Tucson Way, Suite 125, Englewood,CO 80112; 1Phone: (303) 778-8355,1E-mail: [email protected]; 2Phone: (303)790-1340, 2E-mail:[email protected].

Communication with and involvement ofthe public are critical aspects of any environ-mental investigation or cleanup. Experience attwo of the highest profile residentialremediation sites in Denver, Colorado (oneinvolving soil cleanup at over 500 homes and

the other involving indoor air testing at over150 homes), demonstrate that communityrelations issues are even more important, andchallenging when the investigation and cleanupoccur at residential properties. Communityissues at sites involving remediation in homesand yards are different than those at a removedplant site or manufacturing facility. Commu-nity opinion and emotions can influenceregulator’s decisions on remediation, monitor-ing, and long-term site use. The invasivenature of these cleanups requires access to bearranged with each property owner.Homeowners have more of a personal invest-ment and say in the cleanup activities at theirhomes or yards. As a result, extensive com-munications, sensitivity, and flexibility are thecritical elements to establishing and maintain-ing a positive relationship with the home-owner.

In working on these sites, Sigler Commu-nication, Inc., a communications/communityrelations consulting firm, and EnviroGroup,Ltd., an environmental consulting firm, workedclosely together to:

♦ Develop strategies that would gaincommunity cooperation for theremediation projects;♦ Obtain community input to ensureresidents needs were being met; and,♦ Keep residents constantly informedto help alleviate problems encoun-tered during cleanup and monitoringand keep projects on schedule.

Comprehensive, proactive communica-tions and community outreach programs weredeveloped at both sites that include the follow-ing activities:

♦ Conducting community opinion re-search to determine concerns andidentify the best ways tocommunicate.

♦ Implementing a comprehensiveoutreach program that includes thesame staff members setting up


appointments and making in-homevisits for monitoring. Staff membersdevelop a personal relationship withhomeowners to ease apprehensionabout “outsiders” in the home andgain more cooperation. Keeping apersonal information notebook (e.g.,pets and upcoming vacations) allowsstaff members to establish a persondialogue with the homeowners.

♦ Establishing a close working rela-tionship with regulators to ensureconsistent information is beingdelivered to the public.

♦ Hosting public information openhouses that allow the public to askquestions and learn about next stepsfrom the technical team.

♦ Distributing written materials, videos,and newsletters regularly to updatehomeowners on project status.

♦ Developing an information source inthe community staffed by a communitymember that houses cleanup photosand information.

♦ Establishing a telephone hotline up-dated monthly that homeowners cancall for updates on the project.

♦ Making technical staff available to meetone-on-one with homeowners.

♦ Tracking real estate transactions in theneighborhood to answer thehomeowners’ questions about realestate values.

Key words: community, involvement, commu-nications, residential

PostersAnalytical Methods

P1

MEASURING MASSDEPLETION BY DISSOLU-TION OF ENTRAPPEDNONAQUEOUS-PHASELIQUIDS IN FRACTUREDMEDIA WITH X-RAYS

1Joseph McGahee and 2Tissa Illangasekare,1Colorado School of Mines, 1012 14th Street,Golden, CO 80401; 1Phone: (303) 384-2237,1E-mail: [email protected]; 2AMAXProfessor, Division of Environmental Scienceand Engineering, Colorado School of Mines,1012 14th Street, Golden, CO 80401; 2Phone:(303) 384-212, 2E-mail: [email protected].

Nonaqueous-phase liquids (NAPLs) posea potential risk to humans when released intothe environment. Once a NAPL is releasedinto the environment, it could have the abilityto contaminate the groundwater and nearbybodies of water. With this in mind, the dissolu-tion of NAPLs needs to be better understoodin order to adequately predict the impact ofthese contaminants in the subsurface, as wellas for determining the best remediation pro-cess for removing the NAPL.

The ability to detect spatial differencesand to monitor changes in the various phaseswithin a porous medium is vital to enhancingthe information extracted from multi-phaseflow and transport experiments. Radiationattenuation techniques have been productivelyused in multi-phase research at ColoradoSchool of Mines and elsewhere with the use ofradioisotopes (gamma rays). X-ray generatorscan theoretically offer advantages as a radia-tion source in the nondestructive measurementof phase fractions in porous media as com-pared with radioisotopes emitting photons ofsimilar energy. This is true because x-raygenerators can produce a photon flux two tothree orders of magnitude greater than radio-isotopes, thus allowing the time necessary totake a measurement to be reduced. Also,photon energies can be optimized to yield the


best measurement precision for a given experi-ment by choosing the voltage setting on the x-ray generator and by filtering the emittedradiation spectrum with filters. X-ray genera-tors have been shown to have enough flexibil-ity in photon-energy settings to allow accurateand precise measurements, and sufficientphoton flux and detector throughput to per-form these measurements in short durations.

Currently, gamma rays are being used inthe laboratory at Colorado School of Mines tomeasure the location and dissolution of NAPLsin porous media. With the use of x-rays, betterresolution and accuracy will be obtained inmeasurements compared to the use of gammarays. Once the x-ray generator is assembled,experiments will be performed to measure thedissolution of NAPLs in fractured media, aswell as various other experiments. This x-raysystem will also be used in conjunction withthe gamma system in order to better under-stand and determine the behavior of NAPLs inporous media.

Key words: fracture, x-rays, dissolution,NAPL, radioisotopes

P2

COMPARATIVE ANALY-SIS OF RESPIROMETRYAND DIESEL DEGRADA-TION

1Cynthia Davis, 2Tissa Illangasekare, 2FrankBarranco Jr., 3Denton Mauldin, and 4KenVogler, 1,2Environmental Science and Engi-neering Division, Coolbaugh Hall, 14th andIllinois St., Colorado School of Mines,Golden, CO 8040; 3,4Safety-Kleen Consulting,5665 Flatiron Parkway, Boulder, CO 80301;1Phone: (303) 384-2237, 1E-mail:[email protected]; 3Phone: (303) 938-5500, 3E-mail: [email protected],4Email: [email protected].

Respirometry is one method available tomonitor biodegradation kinetics of hydrocar-bon contaminants that degrade aerobically in

soil media. Few field or laboratory studies,however, have validated respirometry informa-tion with confirmatory analysis of actualhydrocarbon degradation in soil. The goal ofthis study was to comparatively evaluate(within controlled lab- and pilot-scale condi-tions) biodegradation rates obtained fromrespirometry versus rates obtained from actualhydrocarbon depletion in soil. Initial experi-ments have been performed in small-scalelaboratory bioreactors to determine diesel-degradation rates through oxygen-consump-tion data collected over a period of time.Results show that oxygen depletion occurredsimultaneously with carbon dioxide produc-tion, indicating that aerobic mineralization ofan aged diesel occurred. Analysis of initial andfinal hydrocarbon mass within the bioreactorsindicated that estimates of diesel depletionbased on respirometry were reasonably accu-rate. Evaluation of the data, assuming first-order kinetics, led to calculated degradationrates ranging from 0.5-5.2mg/kg/day, valuesthat are within published ranges for diesel fuel.Pilot-scale studies are currently underway toassess respirometry results versus actualhydrocarbon depletion within simulatedbioventing systems comprised of 3 in. diametercolumns that are up to 5 ft. in length. Respiro-metric testing is being performed on the gas-phase generated at the top of the column,while in situ measurements are being per-formed spatially within the soil to determinehydrocarbon depletion. In this way, the valid-ity of respirometric data to quantify hydrocar-bon degradation is being evaluated.

Key words: remediation, degradation,respirometry, bioventing, diesel


P3

DEVELOPMENT OF ABIOSENSOR FOR ATRA-ZINE

1Neema Das and 2Kenneth Reardon, 1,2Depart-ment of Chemical and Bioresource Engineer-ing, Colorado State University, Ft. Collins,CO 80523-1370; 1Phone: (970) 491-1137, 1E-mail: [email protected]; 2Phone:(970) 491-6505, 2E-mail:[email protected].

Atrazine is one of the most commonlyused herbicides. It affects metabolic processeswithin weeds, resulting in chlorosis and even-tual death. It is moderately persistent in soil(t

1/2=4-57 weeks) and does not sorb strongly to

the soil matrix. These properties have led togroundwater contamination following over-application and spills of atrazine. Hence,continuous monitoring of the atrazine concen-tration in groundwater is desirable.

The aim of this study is to design abiosensor that will measure atrazine concentra-tion in groundwater. This biosensor is basedon measurement of pH change, which isproportional to the concentration of atrazine.The tip of the biosensor is coated with twolayers. The first layer contains a pH-sensitivefluorescent dye and the second layer containsbacteria (Pseudomonas sp. ADP orClavibacter michiganese sp. ATZ1) immobi-lized in an alginate medium. These microor-ganisms use atrazine as a substrate and pro-duce HCl. The production of acid lowers thepH and this change is detected by the firstlayer.

The biosensor made from Clavibacter hasshown high specificity for atrazine in compari-son to other commonly found groundwatercontaminants (toluene, ethylacetate and chlo-robenzene) and naturally occuring chemicals(aminoacids). It has shown a large responsefor simazine (84% that of atrazine response).It has high sensitivity, with a detection limit of1 ppb (lowest measurement taken is 60 timesthe background noise). The response of thisbiosensor is linear for atrazine concentrations

from 1 ppb to 100 ppb. It has high reproduc-ibility at low concentrations. Most (95%) ofthe total signal change is observed in 10minutes, which is one-third of the responsetime. It loses 45% of its activity in 6 days.The biosensor performance at various tem-peratures and pH is also studied. The biosen-sor made from Pseudomonas measured atra-zine concentration from 25 ppb to 150 ppb.Its response became non-linear at high concen-trations and it lost 72% of its activity in twodays.

Key words: biosensor, immobilization

PostersContaminants in Porous Systems

P4

SURFACTANT-ENHANCED DISSOLU-TION AT ELEVATEDTEMPERATURES

1Quentin Robert Moore and 2TissaIllangasekare, 1Colorado School of Mines,1012 14th Street, Golden, CO 80401; 2AMAXProfessor, Division of Environmental Scienceand Engineering, Colorado School of Mines,1012 14th Street. Golden, CO 80401; 1Phone:(303) 384-2237; 1E-mail:[email protected]; 2Phone: (303) 384-2126; 2E-mail: [email protected].

The release of light nonaqueous-phaseliquids, or LNAPLs, by surface spills, leakingunderground storage tanks, or careless dis-posal practices into the subsurface, has thepotential to infiltrate into the groundwater andcontaminate local aquifers. Due to varyingpumping rates or fluctuating seasonal condi-tions, the height of the water table maychange, thus creating a smear zone of LNAPLcontamination. Large capillary forces immobi-lize the LNAPL in the saturated region belowthe capillary fringe and are stronger than theviscous and buoyancy forces combined. TheLNAPL lens will therefore exist as a residual


covering a large region of soil. Currentremediation technologies are limited by thestrength of the capillary forces; therefore, as anadaptation of enhanced oil recovery in petro-leum engineering, surfactants have receivedmuch attention in recent years as a viablemeans of residual LNAPL remediation. Sur-factants reduce the interfacial tension betweenan organic and an aqueous phase and, there-fore, have the ability to greatly increase themobility of LNAPLs.

The focus of this research is to study thebehavior of a surfactant to decrease the inter-facial tension between an LNAPL and theaqueous phase in the saturated zone of thesubsurface at elevated temperatures to increasethe amount of LNAPL mass recovered. Theeffects of temperature on the LNAPL parti-tioning behavior between the adsorbed andaqueous phases and the possibilities of local-ized density effects are also considered. Sev-eral experiments were run with a well-definedLNAPL source at residual saturation to quan-tify the recovery of an LNAPL. Dissolutionexperiments in a 2D tank provided a means ofdetermining whether a surfactant and anincrease in temperature increase the amount ofNAPL solubilized. As a baseline to compareagainst, a natural dissolution simulation pro-vided a LNAPL mass recovery without theeffects of an added surfactant. Experimentswith a nonionic surfactant injected at roomtemperature directly upstream from theLNAPL contamination studied the rate limitingbehavior and quantified the mass recovery ofsurfactant enhanced dissolution. Lastly, anexperiment injecting the same surfactant at85°C showed the effects of temperature on therelative buoyancy of the surfactant and theresulting mass recovery.

The surfactant-enhanced experimentsshowed a large increase in the amount ofLNAPL mass recovered as compared tonatural dissolution. The amount of massrecovered from the hot surfactant-enhanceddissolution, however, proved to be less thanthe injection of surfactant at room tempera-

ture. It is hypothesized that due to a buoyancyeffect, the hot surfactant injection displacedthe cooler surrounding groundwater as it roseup above the injection point. Once the hotsurfactant cooled, ceasing the upward migra-tion, much of the surfactant had risen higherthan the source of LNAPL contamination andas a result bypassed the LNAPL.

Key words: LNAPL, surfactant, dissolution,residual, temperature

P5

THE EFFECTS OF MICRO-BIAL GROWTH ANDTRANSPORT ON SOILCHARACTERISTICS: AONE-DIMENSIONALANALYSIS

1Rock Richard, 2Tissa Illangasekare, 3AngelaBielefeldt, and 4Anu Ramaswami, 1,2Environ-mental Science and Engineering Division,Colorado School of Mines, Golden, CO80401;3Department of Civil Engineering, Universityof Colorado at Boulder; 4Department of CivilEngineering, University of Colorado atDenver; 1Phone: (303) 348-2237, 1E-mail:[email protected]; 3Phone: (303) 492-8433, 3E-mail:[email protected]; 4Phone:(303) 556-4734, 4E-mail:[email protected].

The use of polyaromatic hydrocarbon(PAH)-degrading microorganisms to treat andcontain dense nonaqueous-phase liquid(DNAPL) soil contamination is an effectiveand efficient solution to an often costly andlabor-intensive problem. The prohibitive costsassociated with traditional cleanup optionssuch as full removal of contaminated soil orvarious pump-and-treat technologies create theneed for such a long-term, low-cost, minimumlabor solution. While the biochemical pro-cesses involved in the breakdown of DNAPL-derived contaminants by microorganisms havebeen well documented, information is currentlylacking on the direct and indirect effects of the


growth and movement of the resultant biomasson the surrounding media.

The goal of this research is to evaluate, inone dimension, the changes in the properties ofporous media associated with microbialgrowth and deposition as well as the subse-quent shearing and redeposition caused bysubsurface flow. To measure these changes,several soil column systems were constructed.A nutrient-solution mixture containing a liveconsortium of PAH-degrading bacteria waspassed through the columns via syringe pumpat rates comparable to real-world low, me-dium, and high groundwater flow rates (lm/yr,10 m/yr, and 100 m/yr, respectively). ThePAH-degrading bacteria consortium consistingof Stenotrophomonas maltophilia, Pseudomo-nas fluorescens, Pseudomonas putida, andPseudomonas stutzeri was cultivated for overone year in a CSTR. The consortium wasexposed to Naphthalene, N-Methyl Naphtha-lene, and Phenanthrene. These constituentswere found to be most abundant, in terms ofmole fractions, in common DNAPLs such ascoal tar. This cultivation procedure wasfollowed in an attempt to create a populationof bacteria representative of those naturallypresent in the soil surrounding a commonDNAPL spill.

Before the microbe solution was circu-lated through the columns, and at regularintervals thereafter, information was gatheredto measure the hydraulic conductivity,dispersivity and porosity of the soil at variousstages of bacterial residence. Microbial con-centration was measured in both the influentand the effluent by means of direct counts viaepifluorescent microscopy as well as a mea-surement of the volatile suspended solids(VSS). Biogrowth density was also measuredthroughout the column length to provideinformation about shearing and redeposition.

The results from this research will beuseful in upscaling to the two-dimensional andfield levels as well as in numerically modelingthe effects of microbial growth and transporton porous media. This in turn could be useful

in designing the most effective biostabilizationand bioremediation systems for treatment ofcontaminated soils.

Key words: biostabilization, bioremediation,DNAPL, PAH, column

P6

LIGHT NONAQUEOUS-PHASE LIQUID WEATH-ERING AT VARIOUS FUELRELEASE SITES

Don Kampbell,EPA/RSKERC, P.O. Box ll98,Ada. OK 74820; Phone: (580) 436-8564,Fax: (580) 436-8703, E-mail:[email protected].

A fuel weathering study was conductedfor database entries to estimate naturalLNAPL weathering and source-term reductionrates for use in natural attenuation models. Arange of BTEX weathering rates from mobileLNAPL plumes at eight field sites with knownrelease dates was documented. Free-phasefuel BTEX weathering rates varied amongsites and were influenced by many factors.First-order weathering rate for five JP-4 fuelsites was 16%/year. Benzene and tolueneexhibited higher weathering rates thanethylbenzene and xylene, as expected, becauseof higher water solubility. The primary weath-ering mechanism of mobile LNAPL wasdissolution. Meaningful determination ofmobile LNAPL weathering rates for BTEX ingasoline was difficult because of the largeranges of initial BTEX values.

Key words: LNAPL, dissolution, naturalattenuation


plistic design) in reducing seepage of untreatedgroundwater through the wall and reducedflow around the end points of the barrier by 57percent. The length and thickness of the gateswere also optimized to provide sufficientresident time of groundwater in the PRB toaccomplish treatment. Important designfeatures affecting PRB performance includeorientation of slurry walls to groundwater flowand contrast between slurry wall and formationpermeability. Minor seepage through theslurry walls may be addressed by short exten-sions of the PRB to capture flow parallel to theslurry wall. The model results were also usedto locate optimum sites for downgradientmonitor wells to assess performance of the ssystem.

Key words: barrier, modeling, PRB

GROUNDWATER MODEL-ING OF A PERMEABLEREACTIVE BARRIER TOENHANCE SYSTEM PER-FORMANCE

1Kenneth Scott, and 2David Folkes,1,2EnviroGroup Limited, 7208 South TucsonWay Suite 125, Englewood, CO 80112;1,2Phone: (303) 790-1340; 1E-mail:[email protected], 2E-mail:[email protected].

Experience has shown that one of themost common reasons permeable reactivebarriers (PRBs) fail to meet performancecriteria is inadequate understanding of thegroundwater flow system. For example,contaminated water may flow around the endsof the barrier or funnelling slurry walls, underthe barrier walls, or through the slurry walls.An analysis of the groundwater flow regimeresulting from the installation of a PRB canlead to an effective design that significantlyreduces the escape of untreated water throughassociated slurry walls and/or around the endsof the PRB system. A three-dimensionalgroundwater flow model using Modflow wasdeveloped to evaluate the effectiveness ofgroundwater capture and treatment resultingfrom the installation of a funnel-and-gate PRB.The reactive barrier was one remedy evaluatedfor containment of an on-site chlorinatedsolvent plume with concentrations of 1,1 DCEranging up to 3,000 ug/l resulting from thedegradation of 1,1,1 TCA and TCE. Theplume is approximately 750 feet wide andflowed off site into a residential area. The on-site plume is of sufficient size that a lineardesign with one or more gates could not beconstructed entirely on site and still providefor complete capture of impacted groundwa-ter. The results of the model analysis providedfor a design that incorporated several barrierand gate segments at varying orientations togroundwater flow for optimization groundwa-ter capture. The model indicated the ideallocation for gates to minimize head increasesalong the upgradient portion of the slurry wall,which resulted (as compared to a more sim-

P7


P8

A STUDY OF SOIL WA-TER-HOLDING PROPER-TIES AS AFFECTED BYTPH CONTAMINATION

1Suzette Burckhard, 2Dan Pirkl, 2VernonSchaefer, 3Peter Kulakow, and 4BlaseLeven, 1,2Civil and Environmental EngineeringDepartment, Box 2219, South Dakota StateUniversity, Brookings, SD 57007; 1Phone:(605) 688-5316, 1E-mail:[email protected]; 3Departmentof Agronomy, 2004 Throckmorton PlantScience Center, Kansas State University,Manhattan, KS 66506; 3Phone: (785) 532-7239, 3E-mail: [email protected]; 4GreatPlains/Rocky Mountain HSRC, 101 WardHall, Kansas State University, Manhattan, KS66506; 4Phone: (785) 532-0780, 4E-mail:[email protected] measurement of soil water content is one ofthe most common kinds of soil analysis per-formed. The potential effects of the soil watercontent on the behavior of soil make it an impor-tant measurement in every type of soil study. Therelationship between soil water content andmetric suction is known as the soil-water charac-teristic curve. The soil-water characteristic curveis often used for calculating unsaturated hydrau-lic values. The introduction of petroleum hydro-carbons into an unsaturated soil, due to a spill,alters unsaturated hydraulic properties of the soil,but current computer modeling of flow in unsat-urated soil does not account for this change inunsaturated hydraulic properties. This presenta-tion will present results from a laboratory experi-ment measuring the hydraulic properties ofcontaminated soils.


PostersBioremediation

P9

BIOREMEDIATION OFMTBE IN THE RHIZO-SPHERE

1Suzanne Bonola and 2Anu Ramaswami,1,2Department of Civil Engineering, Universityof Colorado at Denver, Denver, CO 80217;1Phone: (303) 556-6726, 1E-mail:[email protected]; 2Phone: (303) 556-4734, 2E-mail:[email protected].

Accidental leaks or spills of gasolinecontaining the fuel oxygenate methyl-tert-butylether (MTBE) are of concern because ofMTBE’s high water solubility and low octanol/water partition coefficient (among otherfactors). Once in the groundwater, MTBE canmove at virtually the same velocity as water,whereas benzene and other petroleum con-stituents tend to biodegrade and adsorb to soilparticles. The degradation of MTBE in watercan lead to the formation of tert-butyl alcohol,which can cause some carcinogenic activity inlaboratory animals. Although MTBE isgenerally believed to be resistant to biodegra-dation, research has revealed that microbialbiodegradation, particularly in situ in thevadose zone, may be an effective remediationoption. The goal of this project is to deter-mine the effect of grasses such as Festucaarundinacea (tall fescue) and Medicago sativa(alfalfa) on the degradation of MTBE in soilsystems.

Key words: MTBE, rhizosphere, biodegrada-tion, phytoremediation


P10

NUTRIENT AND SURFAC-TANT ADDITIONS,PYRENE DEGRADATION,AND MYCOBACTERIADIVERSITY IN PAH-CONTAMINATED SOIL

1Pui-Yi Cheung and Brian Kinkle, Departmentof Biological Sciences, P.O. Box 210006,University of Cincinnati, Cincinnati, OH45221-0006; 1Phone: (513) 556-9757, 1E-mail: [email protected].

Polycyclic aromatic hydrocarbons (PAHs)are recalcitrant pollutants produced in fossilfuel combustion or as by-products of manyindustrial processes. There has been growinginterest in the study of fast-growing species ofmycobacteria due to their potential for PAHdegradation. It has been suggested thataddition of nutrients and surfactants maystimulate bioremediation of contaminated sites.However, little is known about the effects ofthese introduced chemicals on microbialcommunity structure and degradative activity.In this study, we measured the mineralizationof 14C-labeled pyrene in a PAH-contaminatedSuperfund soil with and without nutrient orsurfactant amendments. Results showed thatlittle degradation occurred in the control soilwith no supplements. Higher levels of miner-alization occurred when the soil was amendedwith nitrate, phosphate, Triton X-100, orTergitol NP-10. Soils that received 1.5 mg/gsoil of nitrate resulted in a higher level ofpyrene mineralization than those that received0.15 mg/g soil of nitrate. There was no ob-servable difference in the level of mineraliza-tion between soils amended with phosphate at0.15 mg/g or 1.5 mg/g soil. Triton X-100, at aconcentration above its critical micelle concen-tration (CMC), was slightly more effective inenhancing mineralization than below the CMC.In contrast, there was no observable differencein the level of mineralization between soilsamended with Tergitol NP-10 slightly below orabove its CMC. Soil samples will be analyzedby PCR and temperature gradient gel electro-phoresis (TGGE) to determine the relationshipbetween the addition of nutrients and surfac-

tants, patterns of mineralization, and changesin mycobacterial community structure.

Key words: PAH, mycobacteria, surfactant,TGGE

P11

THE EFFECTS OF ETHA-NOL ON BTEX NATURALATTENUATION (PURECULTURE AND AQUIFERCOLUMN EXPERIMENTS)

1Marcio Luis Busi da Silva, 2Nanh Lovanh,3Craig Hunt, and 3Pedro Alvarez, 1,2,3Depart-ment of Civil and Environmental Engineering,2130 SC, University of Iowa, Iowa City, IA52242; 1Phone: (319) 335-5054; 1E-mail:[email protected]; 2E-mail:[email protected].

Although considerable progress has beenmade toward understanding hydrogeochemicalfactors that affect BTEX migration and bio-degradation, little attention has been given tohow differences in gasoline formulation affectnatural attenuation processes. In this regard,the use of ethanol as a gasoline additive isincreasing worldwide, both as a substitute fuelfor imported oil and as an oxygenate to mini-mize air pollution from combustion. Yet, littleis known about the effect of ethanol on bio-degradation and migration of the toxic BTEXcontaminants.

In this work, chemostat experiments wereperformed to investigate the effect of ethanolon aerobic benzene degradation, and to delin-eate the conditions that lead to simultaneousversus preferential biodegradation of ethanolwhen BTEX compounds are present. Chemo-stats were seeded with Pseudomonas putidaF1 (PpF1), and fed benzene and ethanol. Theinfluent benzene concentration was about 1mg/L, and the dilution rate was 0.25 h-1. Theaddition of ethanol to the influent at a concen-tration with equal chemical oxygen demand(COD) to the added benzene resulted in a 70%decrease in the steady-state effluent benzeneconcentration. This effect was representativeof results with carbon-limiting conditions, and


was attributed to an ethanol-supported in-crease in biomass, resulting in faster benzenedegradation rates. When ethanol was added tothe influent at a high enough concentrationthat oxygen became limiting, no significantbenzene degradation occurred. This suggeststhat simultaneous degradation is the normalmode of multiple substrate degradation whencarbon is limiting, and preferential degradationwould occur when carbon is not limiting.

Additional research of the effect ofethanol on BTEX bioremediation is beingconducted. Aquifer columns have been con-structed to study both the biotic and abioticeffects of ethanol on natural attenuation ofgasoline releases. The column is of a largeenough size (120 cm length by 5 cm diameter)and the hydraulic residence time is longenough (~7 days) for anaerobic zones todevelop. One hypothesis for this work is thatethanol will be preferentially degraded underboth aerobic and anaerobic conditions, extend-ing the time and distance required for BTEXconcentrations to be attenuated below regula-tory limits. Theoretical considerations andpreliminary results also indicate ethanol couldincrease BTEX migration velocities by de-creasing sorption-related retardation duringtransport.

In conclusion, the use of ethanol as agasoline oxygenate represents potential eco-nomic and air-quality benefits. Nevertheless,the inhibition of BTEX biodegradation and thepossible decrease in sorption-related retarda-tion suggests that ethanol is likely to increaseBTEX plume lengths. The net effect of etha-nol on natural attenuation of BTEX is likely tobe system specific, depending largely on therelease scenario and the assimilative capacityof the aquifer.

Key words: natural attenuation, ethanol,MTBE, BTEX

P12

BIOLOGICAL SULFATEREDUCTION IN ALKA-LINE WATERS FOR THEREPROCESSING OFTRONA TAILINGS PONDS

1Leigh Ann Boyack, 2Shelly Robertson, and3Patrick Gilcrease, 1,2,3Department of Chemi-cal and Petroleum Engineering, University ofWyoming, P.O. Box 3295, Laramie, WY82071-3295; 1,2,3Phone: (307) 766-2500; 1E-mail: [email protected]; 2E-mail:[email protected]; 3E-mail:[email protected].

Sodium carbonate, commonly known assoda ash, is used in the production of glass,detergents, and other products. In the produc-tion of soda ash from trona ore, crystallizerpurge streams are disposed of in large tailingsponds. The sodium carbonate levels in theseponds are quite high (8 to 14 weight percent);thus, after 50 years of operation, these pondsrepresent a significant potential source ofsodium carbonate. Unfortunately, moderatelevels of sodium sulfate (1 to 2 percent)prevent the further recovery of soda ash fromthese waters. In this research, a novel biologi-cal process which utilizes sulfate-reducingbacteria (SRB) was investigated.

SRBs that can survive the high pH condi-tions of the tailings ponds have been detected.These strict anaerobes have been tentativelyidentified as Desulfovibrio species throughvarious staining techniques. They requireorganic matter for growth and use sulfate as afinal electron acceptor. Soil and water samplesfrom trona tailings ponds were set up inWinogradsky columns to enrich for SRBs.Samples collected from the Winogradskycolumns and site soils were used to inoculatebatch reactors (serum bottles). The batchreactors were used to optimize the organiccarbon source and measure sulfate-reductionkinetics for the cultures. Reduction kineticswere also determined from chemostat data atdifferent dilution rates. The resulting kineticdata will be used to evaluate variousbioreactor designs. Support for this researchwas provided by OCI Wyoming.


Key words: biological sulfate reduction,sodium bicarbonate, soda ash

P13

AGRICULTURE-BASEDREMEDIATION PRO-GRAM-TECHNOLOGYDEVELOPMENT ANDTRAINING INBIOREMEDIATION

1Charles Kinoshita and 2Traci Sylva, 1,2Uni-versity of Hawaii at Manoa, Department ofBiosystems Engineering, 3050 Maile Way,Gilmore 111, Honolulu, HI 96822; 1,2Phone:(808) 956-8863: 1E-mail:[email protected]; 2E-mail:[email protected].

Bioremediation--the application of bio-logical processes to address environmentalproblems--is among the technologies beingtouted to treat contaminated soils and watersources, and to process wastes. There aresignificant advantages to using bioremediationover other approaches. Most bioremediationprocesses can be performed in situ, whichreduces cost and disruption to operations,simplifies logistics, and minimizes liability.Unlike many traditional methods that relysolely on disposal or containment,bioremediation usually aims to decomposepollutants, and therefore represents a perma-nent strategy, minimizing long-term liability.

Technological commercialization, movingscientific discovery to the marketplace, logi-cally begins with an assessment of the scientificand engineering parameters of the technologyand its potential application in a particularmarket. Widespread adoption depends onacceptance of the technology by the public andby regulators. Many technologies that are atthe commercial or near-commercial stage canproduce significant positive impacts in agricul-tural and military settings, but are not in usebecause specific skills are lacking or becauselittle is known of available technologies or ofproviders of those technologies.

This report describes the University ofHawaii’s component of the Agriculture-Based

Remediation Program (ABRP). The ABRPaims to strengthen bioremediation skills lo-cally, nurture a bioremediation industry thatcan serve Hawaii and other locations in theAsia-Pacific region, and increase public aware-ness of agriculture-based bioremediationtechnologies. The present work consists oftwo components: (1) Technology Develop-ment and Capacity Building and (2) Informa-tion Dissemination and Outreach.

The primary objective of the first compo-nent, Technology Development and CapacityBuilding, is to strengthen biologically basedenvironmental remediation skills to support themilitary and agricultural sectors locally andnationally, and help develop a bioremediationindustry that has the capability to share tech-nologies and services internationally. This isbeing achieved by assessing the appropriate-ness of existing bioremediation technologiesand the professional pool in Hawaii and target-ing efforts and resources to strengthen defi-ciencies. Particular emphasis is being given toABRP-supported projects and technologies;filling critical voids in analytical and otherindustry-supporting capabilities; and workingwith the Governor’s Millennium WorkforceDevelopment Initiative subgroup, which isfocused on the development of an environmen-tal workforce in Hawaii.

The primary objective of the InformationDissemination and Outreach component is toprovide formal training to educators, govern-ment agencies, and the general public onadvances in bioremediation and increase publicawareness of the social and economic benefitsof environmental restoration through agricul-ture-based bioremediation. These are beingachieved by providing training to universityand secondary-education faculty and govern-ment agencies; offering courses and hands-ontraining in environmental remediation tosecondary-school and university students aswell as post-graduate professional training;and disseminating information onbioremediation activities that are taking placeunder ABRP.


Key words: bioremediation,phytoremediation, environmental remediation,community outreach

PostersPhytoremediation--Organics

P14

METABOLISM OFTRICHLOROETHYLENEIN HYBRID POPLAR

1Annette Dietz and 2Jerry Schnoor, 1Depart-ment of Civil and Environmental Engineering,122 ERF, University of Iowa, Iowa City, IA52242; 2Department of Civil and Environmen-tal Engineering, 116 ERF, University of Iowa,Iowa City, IA 52242; 1Phone: (319) 335-5053, 1E-mail: [email protected].

Phytoremediation efforts often use hybridpoplar trees, which may prove to be an inex-pensive method of cleaning up groundwatercontaminated with trichloroethylene. Hybridpoplar trees have been shown to take up andconvert trichloroethylene to trichloroaceticacid, dichloroacetic acid, and trichloroethanol.These metabolites indicate that TCE may betransformed via an oxidative pathway similarto that found in mammalian systems, possiblyinvolving a cytochrome P450-type enzyme.The subcellular microsomal fraction wasisolated from hybrid poplar leaf tissues, andwas tested for the ability to convert trichloro-ethylene to trichloroacetic acid. The effects ofknown inhibitors and inducers of cytochromeP450s on the formation of trichloroethylenemetabolites were studied.

Key words: phytoremediation, trichloroethyl-ene, cytochrome P450, poplar

P15

ENHANCEDPHYTOREMEDIATION OFSMEAR-ZONE SOILSTHROUGHOXYGEN ADDITION

1Jeremy Rentz and 2Jerry Schnoor, 1Depart-ment of Civil and Environmental Engineering,125 ERF, University of Iowa, Iowa City, IA52242; 2Department of Civil and Environmen-tal Engineering, 116 ERF, University of Iowa,Iowa City, IA 52242; 1Phone: (319) 339-1005, 1E-mail: [email protected]. Hybrid poplar trees have been shown toclean soils and groundwater contaminated withhydrocarbons. The most successfulphytoremediation projects have cleaned siteswith moderate concentrations of contaminantsat shallow depths. One limitation of thetechnology is often the presence of a “smearzone,” an area of soil with elevated levels ofcontamination that is often anaerobic. Thesetwo characteristics serve to inhibit the roots ofpoplars from penetrating and cleaning the soil.It has been hypothesized that poplar trees cantransport oxygen to anaerobic soils, but thischaracteristic has not been shown experimen-tally. In an effort to increase the usefulness ofphytoremediation, the addition of oxygen tosoils by chemical and physical means wasinvestigated. The addition of oxygen to soilsmay aid in the penetration of smear-zone soilby the roots of hybrid poplar trees. Hybridpoplar (Populus deltoides x nigra DN34)cuttings were planted in eight-inch plastictubes filled with soil from a former refineryand spill site at Heath, Ohio. The top 1.5 feetof soil in the tubes was excavated from a depthof zero to four feet at Heath, Ohio, withbackground levels of hydrocarbon contamina-tion. The soil from 1.5 to 2.5 feet was exca-vated from Heath, Ohio, from depths of ten tofourteen feet. Six inches of gravel were addedfor adequate drainage. Five different experi-mental setups were used to evaluate variousmethods of oxygen transfer to roots and soils.Two methods for ORC (oxygen release com-pound) application and two different aerationtube configurations were tested along with one


set of tubes without oxygen addition. Growth,root density with depth, and final hydrocarbonconcentration were used to evaluate thevarious scenarios.

Key words: phytoremediation, oxygen, poplar

P16

PHYTOREMEDIATION OFA PETROLEUM REFIN-ERY LAND TREATMENTUNIT

Katherine Gomez and Jodi Shann, Universityof Cincinnati, Department of BiologicalSciences, 821 A Rieveschl, P.O. Box 210006,Cincinnati, OH, 45221-0006; Phone: (513)556-9765, E-mail: [email protected] has shown promise in thelaboratory as a remediation technique fordifferent individual soil contaminants. Fewstudies, however, examine the application ofphytoremediation to actual field sites, whichare often contaminated with a mixture ofcompounds and have complicating factorsassociated with the specific site’s history. Inthis study we investigated the potential forphytoremediation on a Land Treatment Unitthat received petroleum refinery wastes morethen 10 years ago and is currently under aRCRA closure plan. We conducted fieldsampling, lab analysis, and greenhouse treat-ability studies to determine, respectively, thevertical and horizontal distribution of contami-nants on the site, their availability in soil, andsite management strategies that could enhanceremediation. Metal and organic analysis of soilcores sampled from across the site confirmedthe presence of high concentrations of Cr, Pb,Zn, Cu, Ni, and several large ring PAHs withpyrene and chrysene predominating. The levelof contamination varied with location on thesite and depth in soil. The depth and the agingof the contaminants may limit theirbioavailability to plants and microorganismsand the potential for remediation. Plants maybe able to increase the bioavailability of agedcontaminants through release of exudates, orplant root penetration. Sequential extractions

were performed before and after planting todetermine the bioavailability of contaminantsto plants and to see if different plant speciesaffect the bioavailability of compounds to plantuptake or microbial degradation. Previousplantings at the site may have allowedphytoremediation to occur resulting in adistinct upper and lower soil layer. Somepreliminary studies were done with plants inlarge clear columns with each of the layersseparately and with both layers together, todetermine if the layers existed because theroots could not grow deep enough to reach thelower layer or if the lower layer was morephytotoxic. Our results showed that plantswere able to grow on the deeper layer, indicat-ing that limited rooting depth may have beenresponsible for the observed layers. To deter-mine if deep tilling to incorporate the twolayers would allow for more phytoremediation,a treatability study was performed on differentconcentrations of the upper and lower soillayers with several plant species. The speciesused were perennial rye; a mixture of legume,rye, and fescue; lambsquarter; and timothy.

Key words: phytoremediation, petroleumhydrocarbons, bioavailability


P17

VEGETATED TREATMENTOF VEHICLE WASH SEDI-MENTS: DEVELOPMENTOF A DECISION SUPPORTTREE

1Suzette Burckhard, 2Kipp Thompson, 2VernonSchaefer, 3Peter Kulakow, and 4Blase Leven,1,2Civil and Environmental EngineeringDepartment, Box 2219, South Dakota StateUniversity, Brookings, SD 57007; 3Depart-ment of Agronomy, 2004 Throckmorton PlantScience Center, Kansas State University,Manhattan, KS 66506; 4Great Plains/RockyMountain HSRC, 101 Ward Hall, Kansas StateUniversity, Manhattan, KS 66506; 1Phone:(605) 688-5316, 1E-mail:[email protected]; ; 3Phone:(785) 532-7239, 3E-mail: [email protected];4Phone: (785) 532-0780, 4E-mail:[email protected].

There is a need for a support tree that willallow for simple design of the natural treat-ment of a contaminated soil using vegetation.This support tree has the potential to offer thebackground needed for design rather thanrequiring the user to possess this background.This will allow persons seeking choices re-garding information on the design of a naturaltreatment using vegetation to approach thedesign and find simple and generalized solu-tions. The objective of this paper is to showan initial guide for a natural treatment option,decision support tree. The decision supporttree will require input from the user. The inputwould consist of answering a few questionsrelated to the type of contamination, soil, andclimate. From this input, the decision supporttree will provide a list of plants that would besuited to the site. Output from this decisiontree has been designed to work with a graphi-cal user interface to further help environmentalprofessionals design vegetated treatmentoptions.


P18

VEGETATED TREATMENTOF VEHICLE WASH SEDI-MENTS: DESIGNING AGRAPHICAL USER INTER-FACE

1Muralidharan Narayanan, 2Jai BharathReddy, 3Suzette Burckhard, 4David Gustafson,5Larry Erickson, 6Peter Kulakow, and 7BlaseLeven, 1,2,4Department of Computing andInformation Sciences, Kansas State Univer-sity, Manhattan, KS 66506; 3Department ofCivil and Environmental Engineering, SouthDakota State University, Brookings, SD57007; 5Department of Chemical Engineer-ing, Kansas State University, Manhattan, KS66506; 6Department of Agronomy, KansasState University, Manhattan, KS 66506;7Great Plains/Rocky Mountain HazardousSubstance Research Center, Kansas StateUniversity, Manhattan, KS 66506; 1,2,4Phone:(785) 532-6350; 1E-mail: [email protected];2E-mail: [email protected]; 5Phone: (785) 532-4313; 5E-mail: [email protected]; 7Phone:(785) 532-0780, 7E-mail: [email protected].

Graphical user interfaces (GUIs) helpcreate user-friendly interactions between amodel application and an inexperienced user.A GUI helps to package the various softwaretools that are essential for effective userinteractions. The paper presents a GUI basedon mathematical model used for simulating avegetated treatment of a site contaminatedwith petroleum hydrocarbons. The mathemati-cal model, described elsewhere, helps tosimulate fate and transport of water and solutein the subsurface environments. The simulatedresults are graphically displayed as modelpredictions to the user in a friendly and clearmanner. To successfully develop a GUI,integration of components from variousplatforms is essential: (1) Databases compo-nent may be used to retrieve or update infor-mation about specific soil properties, soluteproperties, plant properties, and climaticconditions of the site; (2) Graphical units suchas graphics editor, menu bars, tool bars, anddialog boxes allow the user to generate usefulsite-specific data as input components to the


GUI; (3) The mathematical modeling compo-nent, developed in FORTRAN, is coupled andexecuted using the GUI, based on the gener-ated input component; and (4) The outputcomponent of the GUI is used to display to theuser the model predictions in a graphicalformat. These predictions help the user tomake effective management-related decisionssuch as irrigation and fertilization require-ments. The GUI could also include variousestimates such as the desired cleanup levels,amount of time required for these cleanuplevels, and cost incurred in this treatmentprocess. This GUI would also be a useful toolfor environmental professionals who aremaking decisions with regard tophytoremediation treatment of any contami-nated site.

Key words: GUI, contaminated site, decisionmaking

etated treatment (phytoremediation strategy)are mathematically modeled. Subsurfacegroundwater flow, precipitation events, andtranspiring vegetation significantly influencesoil-water transport. This in turn influencesthe transport and fate processes of contami-nants in subsurface environments. The trans-port of soil-water is modeled in a variablysaturated environment in vertical dimensionand is represented as a Richards equationsupported with a van Genuchten model as itsconstitutive relations. The fate and transportof solutes is coupled to the water transportthrough the Darcy water flux equation. Thesolute transport model considers variousphysicochemical phenomena such as adsorp-tion, volatilization, gas-phase diffusion, bio-degradation by soil microbes, and plant uptakeas fate processes of the solutes. Vegetationmay play an important role by enhancingindigenous soil microbial degradation and byalso absorbing or transpiring the contaminants.Moreover, volatile contaminants could escapeto the atmosphere under the influence ofatmospheric conditions. This condition istreated as an open-contaminant, evaporative-flux boundary condition at the soil surface.The mathematical model is validated withexperiments performed in laboratory columns.The validated model is also employed toinvestigate the fate and transport processes inan actual field site at Ft. Riley, Kansas. Thesite was contaminated with petroleum hydro-carbons. The time scales considered for themodel simulation stretch over seasons ofvarying precipitation events. The modelresults help to predict the soil conditions, plantactivities, and contaminant fate processes inthe soil environments for the simulation pe-riod.

Key words: soil-water transport, vanGenuchten model, petroleum hydrocarbons

VEGETATED TREATMENTOF VEHICLE WASH SEDI-MENTS: MATHEMATI-CAL MODELING OFGROUNDWATER ANDSOLUTE TRANSPORT

P191Muralidharan Narayanan, 2SuzetteBurckhard, 3Larry Erickson,4Peter Kulakow, and 5Blase Leven, 1Depart-ment of Computing and Information Sciences,Kansas State University, Manhattan, KS66506; 2Department of Civil and Environmen-tal Engineering, South Dakota State Univer-sity, Brookings, SD 57007; 3Department ofChemical Engineering, Kansas State Univer-sity, Manhattan, KS 66506; 4Department ofAgronomy, Kansas State University, Manhat-tan, KS 66506; 5Great Plains/Rocky Moun-tains Hazardous Substance Research Center,Kansas State University, Manhattan, KS66506; 1Phone: (785) 532-6350, 1E-mail:[email protected]; 3Phone: (785) 532-4313,3E-mail: [email protected]; 5Phone: (785) 532-0780, 5E-mail: [email protected].

The transport and fate processes of waterand solutes in a contaminated site with veg-


PostersPhytoremediation--Metals

P20

NEWPHYTOREMEDIATIONMETHOD FOR TITECLEANING OF RADIOAC-TIVE-CONTAMINATEDAQUATIC SYSTEMS

Oleksandr Mikhyeyev, Boris Sorochinsky,Mikle Ruchko, and Alexey Prokhnevsky,Institute of Cell Biology and Genetic Engi-neering, National Academy of Science ofUkraine, 148 Zabolotnogo St., Kiev–252143,Ukraine; Phone: +380-44-263-61-67; Fax:+380-10-50; E-mail: [email protected].

The problem of soil and water pollutedwith radionuclides is very important for manycountries. For example, in the Ukraine morethan 4.6 billion hectares of agricultural landsand woods and 2200 occupied properties witha population of about 2.4 million people haveundergone radioactive pollution as a result offailure at the Chernobyl Nuclear Power Station(ChNPS) in 1986. The task of water reser-voirs’ deactivation from short-living radionu-clides is no longer an urgent concern. Unfor-tunately, there is still an unsolved problem ofenvironment cleaning from the long-livingradionuclides like 137Cs and 90Sr. These iso-topes are the main source of irradiation for thepeople and animals in the polluted territories.The preservation of all useful properties mustbe an obligatory condition for the environmen-tal cleanup. Plant-based technologies seem tobe the solution for some cleanup problems.The radionuclides’ low biological availabilitymay limit use of plant technologies forremediation of soils. However,phytotechnologies can be rather effective inaquatic systems where the radionuclides existin the dissolved state. 137Cs and 90Sr isotopesare the main sources of irradiation atChernobyl’s accident territories. The labora-tory investigations took place with sunflowerplants, Indian mustard, and peas. The maximal

transfer factors (TF - magnitude of a ratio ofspecific activity of plant object to specificactivity of a medium, i.e., ground or water) for137Cs are determined in roots of the mustardand were equal to 2350. The maximal TF for90Sr is equal to 374 for sunflower roots. Whenthe plants with large biomass levels were used,the activity of 137Cs was reduced from 90 Bq/Lto 9 Bq/L. The efficiency of water clearingfrom 90Sr was not so effective. The field trialswere carried out at a natural pond located nearYanov village (10-km exclusion zone ofChNPS; the volume of the pond is equal to 18-20 m3). Plants were cultivated directly at thewater surface by using special floated con-structions. The plants have taken out from areservoir more than 380 kBq 137Cs and near1100 kBq 90Sr, respectively 74% and 14%from the initial amount of these isotopes. It isremarkable that many plants can demonstratelarger sorption ability at the conditions ofaquatic culture than other water vegetation.The plant species capable of producing largebiomass levels seems to be a determiningfactor in rhizofiltration technology. Sunflowerplants and pea plants are most preferable fromthis point of view. The results allow a conclu-sion that there is a high degree of clearing ofwater polluted with the soluble forms ofradionuclides and puts into perspective theapplication of this technology. Vegetativebiomass with high activity must be convertedto ash and the ash buried as high activitywaste. It solves the problem of radioactivityand reduction of quantity for such waste. Atthe same time, low-radioactive phytomass maybe used as raw material for the production ofbiogas and allocation of various vegetativeproducts, including some secondary metabo-lites, cellulose, etc.

Key words: ChNPS, radionuclides, aquaticsystems, phytoremediation


P21

USING PLANT BIOTECH-NOLOGY TO INCREASETHE POTENTIAL FORPHYTOREMEDIATION OFMOLYBDENUM ANDTUNGSTEN

Kerry Hale, Steven Stack, and ElizabethPilon-Smits, Colorado State University,Department of Biology, A/Z Building, FortCollins, CO 80523; Phone: (970) 491-3320;E-mail: [email protected].

Phytoremediation, environmental cleanupusing plants, offers a cost-effective and envi-ronmentally friendly alternative to conven-tional methods of pollutant remediation. Weare exploring the potential of using Brassicajuncea (Indian mustard) for thephytoremediation of heavy metals such asmolybdenum (Mo) and tungsten (W). In ourstudy, seedlings were treated with Mo and Wto test their tolerance and accumulation ca-pacities for these elements.

We are also interested in determining themetabolic pathways of these elements inplants. To test whether the sulfate assimilationpathway may be involved in uptake and reduc-tion of these oxyanions, genetically engineeredmustard plants overproducing the enzyme ATPsulfurylase (APS) were compared to normal(wild-type) mustard plants for tolerance andaccumulation of Mo and W. Differencesbetween APS and wild-type were found to besignificant. The transgenic APS plants are ableto accumulate up to 1% of their dry weight asMo, an increase of 40% over wild-type. APSplants also show a decrease in Mo tolerance,as seen in their reduced size, when comparedto wild-type. One explanation for this reducedtolerance to Mo is that ATP sulfurylase reactswith Mo to form unstable esters that result in aloss of ATP. Also interesting is the appearanceof blue compounds within the epidermal/subepidermal layers of the plant tissue whenthe plants are exposed to high concentrationsof Mo and W. It appears that B. juncea isconverting the metal into a blue form that isaccumulated in the periphery of the stem,perhaps as a tolerance mechanism. Overall, B.juncea appears to be a good species for the

phytoremediation of Mo, and the applicationof plant biotechnology may serve to increasethis potential.

Key words: phytoremediation, molybdenum,tungsten

UPTAKE OF METALS ANDPAHS BY BRASSICAJUNCEA AND MEDICAGOSATIVAP22

1Anamaria Bukvic and 2Jodi Shann, 1,2Univer-sity of Cincinnati, Department of BiologicalSciences, 614 Rieveschl Hall, P.O. Box210006, Cincinnati, OH 45221-0006;1,2Phone: (513) 556-9700, 1E-mail:[email protected]; 2E-mail:[email protected].

Phytoremediation is an emerging technol-ogy in which plants remove contaminants fromthe environment. One of the common cleanupstrategies in phytoremediation isphytoextraction where plants participate indecontamination directly through the uptake ofpollutants. Many contaminated sites containcomplex mixtures of organic and inorganiccompounds released from the sameantropogenic sources. Plant uptake mecha-nisms may act differently when pollutants arepresent as mixtures than when they occurseparately. To address this situation, uptake ofPAHs and metals by Brassica juncea (mustard)and Medicago sativa (alfalfa) is being investi-gated. To determine the potential of B. junceaand alfalfa for uptake of the heavy metals, Cd,Ni, and Zn, and the PAHs, pyrene andbenzo[a]pyrene, plants were exposed tohydroponic solutions containing the individualcontaminants or mixtures of them. In hydro-ponics, all factors that would normally inter-fere with plant uptake, such as microbialactivity and adsorption to the soil particles,were eliminated, creating a sterile and homo-geneous experimental environment. Uptakewas determined by metal and/or PAHs lossfrom the hydroponic solution over time andfrom analysis of plant tissues. Metals and


PAHs were determined by AAS, ICP, HPLC,and GC-MS, respectively. Uptake of chosencontaminants, present individually or in themixture, was observed by both model species.Experiments were also conducted on theuptake in B. juncea excised roots using 14Cradiolabeled pyrene and benzo[a]pyrene.Subsequent loss of the contaminants from thetreatment solution was observed over time, aswell as its incorporation in the root tissue.

Key words: uptake, phytoremediation, PAHs,heavy metals

PostersRemediation

PHOTOOXIDATION OFMETHYL-TERT-BUTYLETHER ON TITANIA US-ING A PLUG-FLOW REAC-TOR

Shaogang Chu, Chia-Swee Hong, andRajinder Narang, Wadsworth Center, NewYork State Department of Health, and Schoolof Public Health, State University of New Yorkat Albany, NY 12201-0509; Phone:(518)473-7299, E-mail:[email protected].

The gas-phase photocatalytic degradationof methyl-tert-butyl ether (MTBE) using TiO

2-

impregnated fiberglass mesh was investigated.The kinetics of the photocatalytic process wasmeasured with a continuous flow of reactantsthrough the plug-flow reactor, which wasilluminated with UVA light lamp. A plot of(V/Q)/(C

0-C) versus ln(C

0/C)/(C

0-C) showed a

linear relationship by varying C0, the initial

concentration of MTBE, and measuring C, theconcentration of MTBE in the outlet, where Vand Q represent the volume of the reactor andthe flow rate through the reactor, respectively.The oxidation kinetics of MTBE followed theLangmuir-Hinshelwood model. The effect ofhumidity on the photocatalysis was also exam-ined. The adsorption constant K and rate

constant k was 92.42 L/mmol and 0.07 mmol/L min-1, respectively, under the humidity of15% in comparison to the correspondingvalues of 125.84 L/mmol and 0.14 mmol/Lmin-1 in dry air condition. Both adsorptionconstant and rate constant decreased withincreasing humidity. It indicated that waterproduced from the reaction process is enoughfor the hole scavenging to form hydroxylradicals and extra water vapor-inhibitedMTBE photodegradation. The half-lives ofMTBE with initial concentration of 0.14mmol/L were 1.05 and 0.53 min for 15%humidity and dry air condition, respectively.The reaction by-products have been identifiedby GC/MS. Acetone and tert-butyl formate(TBF) were the primary intermediates. Otherby-products, formaldehyde and tert-butyl,alcohol (TBA) were also detected. Thedegradation pathway of MTBE in the photoca-talysis was believed to be similar to that inTiO

2 slurries. The concentration of carbon

dioxide in the outlet gas was increased rapidlyafter the reactions were initiated. It showedthat MTBE could virtually be completelymineralized after extended reaction time.

Key words: photocatalysis, MTBE, titaniumdioxide, GC/MS

P23

Electrochemical peroxidation (ECP), aproprietary process developed by SUNY atOswego researchers, is an enhancement ofFenton’s Reagent (FR) that utilizes sacrificialsteel electrodes, electricity andstochiometrically balanced applications ofhydrogen peroxide. This process has beenused to degrade aqueous phase organicsincluding petroleum hydrocarbons, MTBE and

P24

TREATMENT OF PETRO-LEUM CONTAMINATEDGROUNDWATER BYELECTROCHEMICALPEROXIDATION

1M. Wunderlich, J. Chiarenzelli, R. Scrudato,and L. Falanga, Environmental ResearchCenter, SUNY Oswego, 319 Piez Hall, Os-wego, NY 13126; 1Phone: (315) 341-3639,1E-mail: [email protected].


P25

KINETICS AND PROD-UCTS OF THE TIO

2 PHO-

TOCATALYTICDEGREDATION OF 4,4’-DICHLOROBIPHENYL INWATER

1Fu Fang, 2Shaogang Chu, 3Chia-Swee Hong,and 4Steven Connor, 1,3Department of Environ-mental Health and Toxicology, School ofPublic Health, State University of New York atAlbany, NY 12201-0509; 2,3,4WadsworthCenter, New York State Department of Health,Albany, NY 12201-0509; 1Phone: (518)486-1830, 1E-mail: [email protected].

Photocatalytic processes in the presenceof titanium dioxide provide an interesting routeto destroy hazardous organic contaminants,such as polychlorinated biphenyls, beingoperational in the UV-A domain with a poten-tial use of solar radiation. In this paper, 4,4’-dichlorobiphenyl (4,4’-DCB) was tested as amodel compound at bench scale. A generator-column technique was used to prepare thePCB aqueous solution. 4,4’-DCB was irradi-ated in a TiO

2 aqueous suspension under UV-

340. The degradation of 4,4’-DCB followedthe Langmuir-Hinshelwood kinetic model atnatural pH. Rate constant k was proportionalto the concentration of TiO

2 up to 5 mg/L.

Adsorption equilibrium constant K of 4,4’-DCB was calculated to be 3.59x 107 L/moland was independent of the concentration ofTiO

2. Pentafluorobenzoyl chloride (PFBC)

was used as a derivatizing agent for hydroxy-lated PCBs. The derivatives were identified bygas chromatography-mass spectrometry (GC-MS) and quantified by using gas chromatogra-phy with an electron-capture detector (GC-ECD). The derivatization method improvedthe detection limits of the targeted compoundsto 19.0 pg/mL for 4’-chloro-4-biphenyl-ol, and12.6 pg/mL for 4,4’-dichloro-3-biphenyl-ol,respectively. The primary by-products in-cluded three hydroxylated PCBs, 4’-chloro-4-biphenyl-ol, 4,4’-dichloro-2-biphenyl-ol, and4,4’-dichloro-3-biphenyl-ol. A first-orderparallel/consecutive reaction model wasdeveloped based on an assumed oxidative

BTEX in groundwater. Bench scale FR hasbeen conducted on petroleum contaminatedgroundwater taken from two recovery wells atthe site of a leaking subsurface storage tank atthe Onondaga Nation located near Syracuse,N.Y. FR treatment reduced benzene, MTBE,ethylbenzene, toluene and total xylenes to non-detect levels within minutes. Subsequent ECPexperiments also showed the elevation ofdissolved oxygen levels in anaerobicgroundwaters during treatment resulting inaerobic conditions. Bench scale ECP experi-ments were also conducted on petroleumcontaminated groundwater from the site of apreviously removed subsurface gasolinestorage tank in Saratoga Springs, N.Y. ECPtreatment of this groundwater resulted incomplete degradation of ethyl benzene, m-, o-,and p- xylene at a pH of 2 and 5. Similarexperiments conducted on petroleum contami-nated groundwater from the site of a subsur-face gasoline release in Amsterdam, N.Y.showed complete destruction of BTEX andphenolic compounds. MTBE was reduced by82% and 97% in duplicate experiments. ECPtechnology has been selected by the New YorkDepartment of Environmental Conservation(NYSDEC) to treat groundwater at theSaratoga Springs and Amsterdam sites. Pilotscale tests will be conducted involving ECPtreatment of groundwater and rechargeupgradient of the plume utilizing dry wells orglass filled infiltration galleries. Geochemicalcharacterization of both groundwaters showsubstantial amounts of ferrous iron facilitatingin-situ Fenton’s Reagent reactions and oxida-tion. Therefore, residual peroxide will bemaintained in the effluent for in-situ reactionswith contaminants sorbed to sediment par-ticles. ECP is also being considered for a pilotscale demonstration to degrade BTEX andMTBE at the Onondaga Nation site, nearSyracuse, N.Y., by the NYSDEC and theUnited States Environmental ProtectionAgency.

Key words: electrochemical peroxidation,petroleum, MTBE, Fenton’s Reagent


mechanism. Time profiles of hydroxylatedPCBs based on the predicted model were inagreement with those from the experimentaldata. Hydroxylation was confirmed to be themajor pathway in the photocatalysis. OHradicals could substitute either hydrogen orchlorine on a phenyl ring. Hydroxylationcould occur at all sites of a biphenyl ringdespite steric hindrance and/or resonanceeffects; however, the ortho position was morefavorable for substitution than meta or parapositions. Other important intermediates wereidentified as 4-chlorophenyl-ethanone, 4-chlorobenzaldehyde, and 4-chlorophenol.Neither 4-chlorobiphenyl nor biphenyl weredetected, which indicated that dechlorinationwas a minor pathway if any. A reactionscheme involving hydroxyl radicals has beenproposed.

Key words: PCB, TiO2, photocatalysis,

derivatization, pentafluorobenzoyl chloride

P26

THE EFFECTS OF LOW-LEVEL RELATIVE HU-MIDITY ON THE CARBONADSORPTION EFFI-CIENCY OF A VOLATILEORGANIC HYDROCAR-BON

1Jefrey Sipple, R. Putnam, and AnuRamaswami, 13226 E. Kansas Dr., K183,Aurora, CO 80012; 1Phone: (303) 338-5390;1E-mail: [email protected].

The removal of volatile organic hydrocar-bons (VOCs) is extremely important to theprotection of human health and the environ-ment. Carbon adsorption is one such technol-ogy which is used to remove these contami-nants with greater than 99% efficiency. Theremoval is facilitated by Van Der Waal forces,which enhance the stability of the bondsbetween carbon atoms which make up thecontaminant and the elemental carbon atomscomprising the carbon bed. Though thisremoval efficiency is slightly lower than incin-eration, it also has a lower overall environmen-tal impact. However, the literature suggests

that under humid conditions (i.e. somewherebetween 30 and 70% or above), solventbonding to activated carbon is impaired,decreasing the overall carbon adsorptionefficiency. Practical experiences indicate thateven a one percent decrease in the overallremoval efficiency by activated carbon can besignificant, especially in instances that cleanupgoals cannot be achieved. It is generallyaccepted that under humid conditions, watermolecules in some way interfere with thebinding sites available to the carbons of thecontaminant, but what effects, if any, lowrelative humidity may have on carbon adsorp-tion is unknown. In fact, all experimentalmodels and data are currently based on therecovery of pure solvents or combinations ofpure solvents, so a model incorporating theeffects of any relative humidity on recovery isunavailable. The major goal of our project isto test the hypothesis that a decrease in thecarbon adsorption efficiency of a pure VOCoccurs under conditions of low relative humid-ity. If this decrease in carbon adsorptionefficiency is a statistically significant one, wewill propose a theoretical, mathematical modelwhich could explain these changes.

PostersMetals-Enhanced Remediation

P27

ZERO-VALENT IRONFOR TREATMENT OFHIGH ARSENIC WATER

1Santhiti Tawachsupa, 2Mehmet Isleyen, and3Anu Ramaswami, 1,2,3Department of CivilEngineering, University of Colorado, Denver,CO 80217; 1Phone: (303) 504-4916, 1E-mail:[email protected].

The international community is urgentlyseeking low-cost, point-of-use arsenic removaltechnologies appropriate for use in rural areasof Bangladesh and West Bengal, India, where


an estimated 76 million people are exposed tohigh concentrations (50 ppb to ~3,500 ppb) ofarsenic in drinking water. The affected popu-lations reside in villages with little electricityand no running water, and they rely on thedrinking water pumped from borewells whichhas been shown to be contaminated with highlevels of arsenic. Low-cost and in-hometreatment technologies are required for rapidremoval of arsenic from the contaminateddrinking waters. This poster presents resultsfrom a screening study designed to evaluatethe efficiency of zero-valent iron for arsenicremoval from water stored in vessels withinindividual homes. Batch equilibrium experi-ments, with initial arsenic concentrations of2000 ppb and 200 ppb, showed arsenic re-moval efficiencies of ~95% with iron in thepresence of sulphate in solution. The kineticsof arsenic removal by iron was examined undervarious conditions. High removal efficiencies(~93%) were observed from high arsenicwaters (2000 ppb) over short contact times(30-40 min) with iron, in the presence ofsulphate in solution. Most rapid arsenicremoval was observed in the absence of air inthe system, while phosphate buffers wereobserved to inhibit arsenic removal by iron.Arsenic was found to be firmly bound on ironfilings in the presence and absence of sulphate.The final concentrations of iron seem to bedependent on arsenic concentration in solution,and it was shown that a dose of iron concen-tration (2,500 mg/L) is suitable for the processto the EPA’s standard for people’s health.

Key words: arsenic, zero-valent iron, watertreatment

P28

REDUTION KINETICS OFINORGANIC CONTAMI-NANTS BY IRON METAL

1Michael Alowitz, 2Ryan Gettler, and 3MichelleScherer, 1,2,3Department of Civil and Environ-mental Engineering, University of Iowa, 4016Seamans Center, Iowa City, IA 52242; 1Phone:(319) 335-6164, 1E-mail; [email protected]; 2Phone: (319) 335-6164,2E-mail: [email protected]; 3Phone:(319) 335-5654, 3E-mail: [email protected].

In recent years, research into zero-valentiron walls has yielded hundreds of papers andover 40 field installations of permeable reac-tive barriers (PRBs). Zero-valent iron is astrong reductant capable of degrading manyoxidized compounds. Reduction of organiccompounds by zero-valent iron is well studied.Observed rate constants (k

obs) for reduction of

chlorinated aliphatic compounds by iron spanmore than three orders of magnitude. Normal-ization of observed rate data to iron surfacearea concentrations has decreased the variabil-ity to a single order of magnitude for mostcompounds. Reactivity of chlorinated aliphaticcompounds with iron correlates well withmeasures of electron affinity such as one-electron reduction potential and the energy ofthe lowest unoccupied molecular orbital(E

LUMO).

Reduction of inorganic compounds byiron metal has not been studied as thoroughlyas the degradation of organic compounds. Weare exploring published kinetic data for reduc-tion of inorganic compounds such as chro-mate, nitrate, and uranium in an attempt toelucidate a correlation between reported rateconstants and several parameters includingreaction pH, iron surface area concentration,and electron affinity. We will also examine therates of reduction by iron from differentsources.

Thc reactivity of iron from differentsources has been reported to vary by morethan would be expected by surface area differ-


ences alone. Iron commercially available inbulk often has a significant oxide layer on theparticles and may contain substantial impuritiessuch as magnesium, carbon, and sulfur. Manycontaminant reduction studies have usedexpensive high purity iron; however, thecheaper bulk iron is used in field installations.We will examine the importance of iron sourceby comparing the kinetics for reduction ofinorganic compounds by several different typesof iron.

The results will aid in the design of ironmetal permeable reactive barriers by providinga better estimate of the expected rates ofreduction of inorganic compounds. Informa-tion about the reactivity of different iron typesmay allow for improved cost analysis andlower construction costs by promoting selec-tion of a more effective iron.

Key words: iron, PRB, reduction, chromate,nitrate

P29

GEOMICROBIOLOGICALINTERACTIONS AMONGIRON SULFIDE MINER-ALS ANDMETHANOGENIC CON-SORTIA

1Jerry Gander, 2Gene Parkin, and 3MichelleScherer, 1,2,3Department of Civil and Environ-mental Engineering, The University of lowa,2130 Seamans Center, lowa City, lA 52242;1Phone: (319) 335-6164; 1Email: [email protected]; 2Phone: (319) 355-5655,2Email: [email protected];3Phone:(319) 355-5654, 3Email: [email protected].

Iron sulfide minerals are common soilconstituents that have been identified in anumber of anaerobic aquatic systems. Ironsulfide minerals are produced primarily viaanaerobic microbial activity where hydrogensulfide produced by sulfate-reducing bacteriareacts with various iron species. The initialiron sulfide species formed is mackinawite,FeS

1+x. Changes in the environmental condi-

tions, including pH, temperature, and exposureto sulfate-reducing bacteria, however, will alterthe iron sulfide minerals to other crystallinestructures such as greigite, Fe

3S

4, and pyrrho-

tite, FeS1+x

. Pyrite, FeS2, (i.e., fool’s gold) is

the most stable form of iron sulfide mineral,and sulfate-reducing bacteria can producepyrite from mackinawite when elemental sulfuris present.

Iron sulfide minerals represent a potentialreductant in the natural attenuation of chlori-nated aliphatic hydrocarbons (CAHs) inreduced anaerobic environments, and it mayhave application as an additive in certainpassive remediation applications using ironmetal as a reductant. Iron sulfide reactionswith hexachloroethane have been shown to beinsensitive to many organic amendments andmild changes in ionic strength, suggesting thatiron sulfide may retain its reactivity in diverseenvironments. In some cases, iron sulfidesmay prove to be more beneficial than ironmetal in CAH degradation. This hypothesis isparticularly promising, given that one ironsulfide form, troilite, has been shown to reactmuch faster than iron metal in trichloroethanedegradation.

Along with independent abiotic transfor-mation processes, iron sulfide minerals couldserve a purpose in CAH degradation duringbiological productive dechlorination processesas well. Methanogenic microbial populationsneed sources of both ferrous iron and sulfideto maintain normal metabolic processes. Thisrequirement for ferrous iron and sulfide impliesthat iron sulfide is present in environmentswhere methanogens thrive. Bothmethanogenic populations and iron sulfideminerals have been shown to reduce CAHsthrough independent processes. What has notbeen investigated is the relationship, if any,between the iron sulfide degradation reactionsand the reductive dechlorination processes ofmethanogens.

To this end, we are investigating the roleof iron sulfide minerals as a source of CAHreduction, both in the presence and absence of


methanogenic populations. This will aid indetermining any relationships between ironsulfide transformation reactions and the reduc-tive dechlorination processes of methanogens,and it could help predict which mechanism(s)dominate within these combined abiotic/bioticenvironments. To assess the interaction of ironsulfide minerals and methanogenic cultures, anumber of laboratory techniques will be used.Preliminary laboratory work has provided amethod of iron sulfide mineral synthesis thathas been confirmed with X-ray powder diffrac-tion (XRD). Formation of iron sulfide miner-als has also been observed via the reduction ofsulfate by iron metal. Due to the high sensitiv-ity to oxygen of both iron sulfide minerals andmethanogenic cultures, synthesis and materialspreparation will be conducted in an anaerobicchamber, and all reactors will be prepared withmethods that simulate anaerobic conditions.Batch and column studies will be conducted toinvestigate the reaction kinetics and productdistribution of CAH reduction in the followingsystems: (1) iron sulfide + CAH contaminant,(2) methanogenic culture + CAH contaminant,and (3) iron sulfide + methanogenic culture +CAH contaminant. Conclusions drawn basedon comparisons of the performance of thesevarious experimental systems will aid in defin-ing the roles of both iron sulfide minerals andmethanogenic populations in natural attenua-tion of CAH contaminants. Preliminary resultshave shown that reduction of 1,1,1-trichloroethane by iron sulfide minerals occurswith a half-life of approximately three days.The products resulting from this reaction havenot yet been identified and are currently beinginvestigated.

Key words: chlorinated hydrocarbons, ironreactive barriers

P30

ABIOTIC REMOVAL OFTETRACHLOROETHENE(PCE) ANDTRICHLOROETHENE(TCE) WITH SAND UNDERVARIOUS CONDITIONS

Lei Wang, Maina Githinji, and RobertSegar Jr., Department of Civil and Environ-mental Engineering, University of Missouri-Columbia, Columbia, MO 65211; Phone:(573) 882-0075; E-mail:[email protected].

This study was conducted to investigatethe extent of tetrachloroethene (PCE) andtrichloroethene (TCE) removal imposed byfive types of sand (quartz, garnet, ilmenite,hematite, and magnetite) and iron filings undervarious conditions. The conditions includedcontrol (medium water only), oxidative (hy-drogen peroxide), aerobic (pure oxygenpurged), anoxic (nitrogen purged), and anaero-bic (nitrogen purged with formate as reduc-tant) conditions. Under control condition,TCE and PCE had no significant removal.Under anaerobic, anoxic, and aerobic condi-tions with and without sand, 20% or less PCEand TCE removal occurred, which was mainlydue to diffusion, volatilization, and errors.Most significant removal occurred whenhydrogen peroxide existed, resulting in 91% ofPCE and 99% of TCE being reduced during12 hours without sand. High-iron-contentsand had no significant effect because thecontent of iron was fully oxidized iron. How-ever, the decomposition rate of hydrogenperoxide was increased 15 to 30 times whensand existed, which decreased PCE and TCEremoval and need to add more hydrogenperoxide. Further continuous flow columnstudies showed that sands had no significanteffect on removal of PCE and TCE. Ironfilings could remove 93% of PCE and 69% ofTCE under anoxic, 82% of PCE and 70% ofTCE under aerobic, and 95% of PCE and 98%of TCE under oxidative conditions. A seriousclogging problem occurred under pure oxygenand hydrogen peroxide conditions with theiron filings.


Key words: tetrachloroethene (PCE),trichloroethene (TCE), hydrogen peroxide,sand (quartz garnet, ilmenite, hematite,magnetite), anoxic, aerobic, anaerobic

Key words: oats, wheat, esterification, heavymetals, phytofiltration

P32

STUDY OF THE BINDINGMECHANISMS OF HEAVYMETALS BY INACTI-VATED TISSUES OFSOLANUMELAEAGNIFOLIUM

1A.E. Rascon, 2K.J. Tiemman, 3K. Dokken, and4J.L. Gardea-Torresdey, 1,2,3,4Department ofChemistry and Environmental Science andEngineering, University of Texas at E1 Paso,E1 Paso, TX 79968; 4Phone: (915) 747-5359,4E-mail: [email protected].

Contamination caused by heavy metalpollution has been long known, as well as itsadverse and toxic effects on the environmentand mankind. It has also been observed thatsome native plants have survived within theseareas polluted with heavy metals. This hasbeen observed with Solanum elaeagnifolium(silverleaf nightshade), which is considered tobe a noxious weed in some states. This woodysubshrub has shown to uptake high concentra-tions of metals. We can take advantage of thissingular feature to use the Solanumelaeagnifolium’s inactivated tissues as abiofiltration system. First, it is necessary tocharacterize the mechanism of the bindingbetween the biomass tissues with heavy metalsby using chemical modification techniques.These techniques include chemical esterifica-tion and hydrolyzation of carboxylic groups,respectively. We have performed studies withesterified and hydrolyzed biomass in order todetermine the effects on metal binding. Thesestudies have shown an overall decrease inmetal binding for esterified biomass, and anoverall increase for hydrolyzed biomass ascompared to the unmodified biomass. Theseexperiments were performed with Cu(II),Pb(II), Cr(III), Zn(II), and Ni(II). In addition,experiments conducted with modified biomassat different pH conditions were performed inorder to verify these results. Finding themechanism of the metal binding by the

STUDY OF METAL IONBINDING TO CHEMI-CALLY MODIFIED OATAND WHEAT BY-PROD-UCTSP31

1V. Armendariz, 2L. Bess-Oberto, 3K.J.Tiemann, and 4J.L. Gardea-Torresdey, 1,2,3,4De-partment of Chemistry and EnvironmentalScience and Engineering, University of Texasat E1 Paso, E1 Paso, TX 79968; 4Phone:(915) 747-5359, 4E-mail: [email protected].

Oat and wheat by-products have demon-strated an ability to bind heavy metal ions inaqueous solutions. Previous studies haveshown that different non-living biomaterialshave the ability to bind metal ions via carboxylgroups. In order to determine what rolecarboxyl ligands have on the metal binding byoat and wheat agricultural by-products, chemi-cal modification experiments were performedusing acidic methanol to block these ligands.The effects of esterification on the metal ionbinding to oat and wheat biomasses werestudied at pH 2.0 and 5.0 in batch experimentsusing 0.3mM solutions of chromium(III),chromium(VI), copper(II), zinc(II), lead(II),cadmium(II), and nickel(II). Results of thisexperiment showed that there was a decreasein metal binding due to esterification for mostof the metal ions studied except for Cr(VI).This data indicates that carboxylic groups arethe major binding site in oat and wheat biom-ass for most of the metal ions studied. Thisinformation will be important for determiningthe potential use of agricultural waste to cleanheavy metal ions from contaminated waters.

PostersSorption, Binding, and Precipitation


Solanum elaeagnifolium biomass is the basison which any bioremediation (biofiltration inthis case) system should be built. In addition,we used XANES and EXAFS techniques toelucidate the mechanism(s) of metal ion bind-ing. Results of these experiments will bepresented.

Key words: biofiltration, chemical modifica-tion, heavy metals, Solanum elaeagnifolium

P33

CHARACTERIZATION OFCHROMIUM(VI) BINDINGAND BIO-REDUCTION BYAVENA MONIDA (OAT)BIOMASS

1L. Bess-Oberto, 1V. Armendariz, 1K.J.Tiemann, and 2J.L. Gardea-Torresdey, 1,2De-partment of Chemistry and EnvironmentalScience and Engineering, University of Texasat El Paso, El Paso, TX 79968; 2Phone: (915)747-5359, 2E-mail: [email protected].

The contamination of chromium(VI) inthe environment and the consequences of thispotential health threat have become an impor-tant issue. Conventional technologies to cleanup heavy metal from contaminated waters havebeen utilized, but they are not cost-effective.Agricultural waste by-products may be a newcost-effect alternative for the removal ofchromium(VI) from contaminated waters. Oatby-products from the Juarez Valley in Mexicowere studied for the ability to bindchromium(VI) under temperature and timeeffects. Batch experiments were performed atvarious time exposures and temperatures todetermine their effects on the chromium(VI)binding capacity by oat biomass at pH 2.0.The metal-binding ability of oats was calcu-lated from experimental data collected at timeexposures of 1, 6, 24, 48, and 72 hours at eachtemperature of 8°C, 26°C, and 54°C. Theseresults showed that the binding of Cr(VI) tooat biomass increased with increasing time andtemperature. The chromium recovery fromoat biomass was performed by treatment with0.2 M HC1. The strippings were further

analyzed with UV-VIS spectroscopy where itwas determined that chromium(VI) wasreduced to chromium(III) by the oat biomass.These results were confirmed using x-rayabsorption spectroscopy which proved thereduction of Cr(VI) to Cr(III). This agricul-tural waste by-product could be a good alter-native for the removal of chromium(VI) fromcontaminated waters and for the minimizationof the contaminated levels in water due to thereduction of Cr(VI) to Cr(III).

Key words: chromium(VI), bioreduction, oats,agricultural byproducts, XANES

P34

ADSORPTION AND RE-COVERY OF SILVER IONSFROM AQUEOUS SOLU-TIONS BY MEDICAGOSATIVA (ALFALFA) BIO-MASS

1I. Herrera, 1K.J. Tiemann, 1K. Dokken, 1G.Gamez, 1J.G. Parsons, and 2J.L. GardeaTorresdey, 1,2Department of Chemistry andEnvironmental Science and Engineering,University of Texas at El Paso, El Paso, TX79968; 2Phone: (915) 747-5359, 2E-mail:[email protected].

Silver is a widely used metal in electron-ics, jewelry, medical products, and photo-graphic products. However, silver becomes awaste product after these industries employ it.The photographic industry itself produceswaste containing from 3000 to 5000 ppm ofsilver. Current methods for recovery of silverions are very expensive and not very effectivein this industry. The use of biological systems,such as the alfalfa, have shown to be cost-effective methods to clean heavy metal ionsfrom contaminated waters. This technologymay be a plausible approach for recoveringsilver ions from photographic waste solutions.We have found that alfalfa biomass binds silverin a pH-dependent manner within a period ofabout 5 minutes. Binding capacity studieswere conducted with the alfalfa biomass aswell as hydrolized, esterified, amino-modifiedand sulfhydral-modified in order to determine


P35

the binding sites involved in the binding pro-cess. Binding comparison studies were con-ducted with a weak cation exchange resincontaining carboxylic ligand. Temperaturestudies were conducted to assess the behaviorof silver ion binding at different temperatures.Flow studies were performed using silica-immobilized alfalfa biomass at different light-ing conditions to observe the effect on silverion binding. We also determined that thebound silver ion can be removed by using a 0.1M solution of thiourea acidified. This will leadus to an environmentally friendly system thatwill recover this precious metal in a cost-effective way.

Key words: silver, weak cation exchanger,alfalfa, adsorption, columns

MODEL DEVELOPMENTAND SIMULATION OF INSITU REMEDIATION INLEAD-CONTAMINATEDSOILS

1Zhiao Shi and 2Larry Erickson, 1,2105Durland Hall, Department of ChemicalEngineering, Kansas State University, Man-hattan, KS 66506; 1Phone: (785) 532-4323,1Email: [email protected]; 2Phone: (785) 532-4313, 2Email: [email protected].

Remediation of Pb-contaminated soils hasreceived considerable attention recently.Amending Pb-contaminated soils with phos-phate as an in situ remediation option has beenproposed as an alternative of other remediationoptions such as soil removal. Research showsthat hydroxyapatite [Ca

5(PO

4)

3OH] can reduce

the bioavailability of Pb efficiently and thus isconsidered as an ideal phosphate source.Environmental models are increasingly beingrelied upon to help identify the limiting factorsin such kind of in situ remediation.

In the present work, models which in-clude adsorption, diffusion, and reaction havebeen developed to describe the transformationof lead contaminants to pyromorphite in singleparticles, aggregates, and soil beds, respec-

tively. Principle factors controlling the time ofremediation have been identified.

The contaminated aggregatesremediation(CAR) model has been developedand simulated to describe the effect of initialcontaminant concentration, partition coeffi-cient, and aggregate radius on the time ofremediation.

Key words: modeling, remediation, hydroxya-patite, lead pyromorphite, bioavailability

P36

EFFECT OF PEROXIDASEADDITION ON SORPTION,DESORPTION, AND BIND-ING OF PHENOLIC MIX-TURES IN SOILS

1Fangxiang Xu and 2Alok Bhandari, 1,2Depart-ment of Civil Engineering, Kansas StateUniversity, Manhattan KS 66506-2905;1,2Phone: (785) 532-7717; 1E-mail:[email protected]; 2E-mail:[email protected].

Peroxidase and phenol-oxidase enzymescan catalyze oxidative coupling reactions thatresult in the polymerization of phenolic con-taminants in aqueous systems. When theseenzymes and necessary cofactors are added tosoils, they can enhance the rate and extent ofcontaminant binding to soil organic matter in aprocess analogous to humus formation. Thecontaminant is immobilized within the soilmatrix and is prevented from transport viasurface runoff or leaching into the subsurface.The strong contaminant-soil interactions resultin reduced ecotoxicity and, therefore, hold thepotential to attenuate health risks withoutnecessarily removing the pollutant from thecontaminated media. Another attractivefeature of enzyme-based engineered humifica-tion is that this approach can be used to treatsoils contaminated with mixtures of phenolicchemicals present in a wide range of concen-trations. The study presented here focused onevaluating the distribution and binding ofphenol-dichlorophenol-naphthol mixtures ontwo sandy loams belonging to the Haynie


series. One soil was obtained from an agricul-tural field (1.7% organic matter) while theother was collected from an adjacent forestedarea (2.6% organic matter). To reduce theinfluence of dissolved organic matter, bothsoils were washed several times before use inthe experiments. U-ring-14C-labeled targetchemicals were used to improve detectionlimits and better track the distribution of thepollutant among various soil components.Bottle-point adsorption experiments withconstant soil dosage were conducted for aperiod of 7 days followed by sequential extrac-tion (desorption) with synthetic groundwater.The strongly adsorbed chemicals were re-moved by multiple extractions with methanol.Next, the soil was extracted with alkali under anitrogen atmosphere to remove humic andfulvic acids and quantify the contaminantassociated with this fraction. Finally, thephenol remaining on the alkali-extracted soilwas quantified by combusting the soil at 925°Cand counting the 14CO

2 on a liquid scintillation

counter. The effect of the presence of horse-radish peroxidase on the nature and extent ofbinding was compared to situations when noperoxidase was added. Results showed adramatic enhancement in contaminant bindingin the presence of the enzyme.

Key words: soil, phenols, binding, peroxidase,humification

P37

DETERMINATION OFLONG-TERM STABILITYOF METALS IMMOBI-LIZED BY IN SITU MI-CROBIAL REMEDIATIONPROCESSES

Scott Simonton, Mark Dimsha, George Cathy,Bruce Thomson, and Larry Barton, Universityof New Mexico, Department of Civil Engi-neering; Phone: (505) 277-1309; E-mail:[email protected].

Most microbial remediation strategiesthat have been developed for addressing sitescontaminated with metals and inorganic radio-

nuclides incorporate anaerobic organisms toachieve in situ reduction and precipitation ofthe contaminants. The pollutants are expectedto remain immobilized provided that reducingconditions are maintained in the subsurfaceformation; however, little information has beendeveloped on the stability of these precipitatesover very long time periods. This project hasinvestigated the long-term stability of metalsand radionuclides immobilized by microbialprocesses through use of laboratory researchand numerical modeling.

The research has focused on arsenic (As),chromium (Cr), selenium (Se), and uranium(U) as being representative of contaminantsfound at many DOE sites, including uraniummill tailings sites. The laboratory work hasinvolved operation of columns packed withcoarse sand, inoculated with anaerobic bacte-ria, and fed a simulated groundwater solutioncontaining the metal, or metals, or radioactivecontaminants and a soluble organic substrate.Two different organisms have been used,Desulfavibrio desulfuricans and Shewenellaputifacciens. The purpose of these columns isto generate sand media containing high con-centrations of the contaminants for use insubsequent leaching experiments. They haveoperated for more than one year.

To date, samples of the sand media withimmobilized pollutants have been subjected toleaching by deionized water solutions and byweak acetic acid solutions specified in thetoxicity characteristic leaching procedure(TCLP). The contaminants immobilized by D.desulfuricans culture have been found to bequite stable in a deionized water leach testover a period of time extending into one week.These contaminants are less stable in the weakacid of the TCEP test. Vigorous mixing of themedia as called for in the TCLP test diminishesthe stability of the immobilized pollutants dueto the fragile nature of the microbial floc.Testing is continuing with contaminants immo-bilized by S. putrifaciens culture. Long-termleaching studies are in progress using simu-lated groundwater to generate information on


the rate of contaminant release. A one-dimen-sional coupled transport and geochemicalkinetic code has been selected to use thisinformation to predict contaminant concentra-tions down-gradient from a site at which insitu microbial immobilization has been imple-mented.

Key words: anaerobic microbial reduction,metals, stability

PostersRisk/Bioavailability

P38

DETERMINATION OFGENOTOXICITY OFWOOD-PRESERVINGWASTE-CONTAMINATEDSOIL

1S.S. Garcia, 2G.-D. Zhou, 2K. Randerath, and1K.C. Donnelly, 1Department of VeterinaryAnatomy and Public Health, Texas A&MUniversity, College Station, TX 77843-4458;2Department of Pharmacology, Baylor Col-lege of Medicine, Houston, TX.

Soil samples were collected from a sitecontaminated with wood-preserving waste(WPW) and undergoing bioremediation.WPW is a complex mixture containing severaldifferent toxic compounds, including polycy-clic aromatic hydrocarbons (PAHs). Theobjective of this research is to determinewhether current risk guidelines based onchemical parameters are protective of humanhealth. Over the past two years, soil samplesrepresenting different time points post-treat-ment (Days 0, 90, 360) have been collected.Extracts of the soils were tested for mutage-nicity in the Salmonella microsome assay andfor formation of DNA adducts in a 32P post-labeling assay. Chemical analysis was per-formed by GCMS. For the sum of ten carcino-genic PAHs, results for representative samplesfrom each time period were as follows: Day 0at 100 ppm; Day 90 at 38 ppm; Day 360 at 32ppm. In the Salmonella assay, each of these

samples produced a positive result (doublingof revertant colonies at two consecutive doses)with metabolic activation by S9 rat liverhomogenate. Average revertants at a dose of1 mg/plate were Day 0 at 98±19; Day 90 at126±11; and Day 360 at 138±84. For thepost-labeling assay, female ICR mice weredosed by painting sample extract dissolved inmethylene chloride on a shaved area on theback. Skin, liver, kidney, and lungs werecollected. For DNA adducts isolated fromskin treated at a dose of 3 mg extract/mouse,the Day 0 sample had a total relative adductlevel of 127x109. For days 30 and 360, theRAL were 157x109 and 92x109, respectively.These preliminary results indicate that whilechemical concentrations are decreasing overtime, genotoxic compounds are still present inthis soil.

Key words: genotoxicity, mixtures, soil

P39

PARTIAL PRESSUREDATA AS AN INSIGHTINTO MECHANISMS OFDERMAL ABSORPTIONOF SOIL CONTAMINANTS

1Chen-Peng Chen, 2Donald Macalady, and3Annette Bunge, 1,3Department of ChemicalEngineering and Petroleum Refining, Colo-rado School of Mines, 1500 Illinois Street,Golden, CO 80401; 2Department of Chemistryand Geochemistry, Colorado School of Mines,1500 Illinois Street, Golden, CO 80401;1Phone: (303) 384-2016, 1E-mail:[email protected]; 2Phone: (303) 273-3996, 2E-mail: [email protected];3Phone: (303) 273-3722, 3E-mail:[email protected].

Dermal absorption is a potentially signifi-cant route for human exposure to toxic chemi-cals present in contaminated soils. Despite itsimportance, the mechanisms of dermal absorp-tion from such exposure remain largely un-known. However, existing data do suggest


that soil-to-skin transfer may be the controllingstep.

The long-term goals of this research are(1) to identify the significant physicochemicalmechanisms involved in soil-to-skin transfer,(2) to understand interactions among thesemechanisms and the corresponding changes inthe dermal uptake of chemicals, and (3) toestablish parameters appropriate for develop-ing consistent protocols for assessing thehealth risks associated with dermal exposure tocontaminated soils. In our initial studies, wehave focused on two related questions: (1)how does contaminant concentration on/in thesoil affect soil-to-skin transfer and (2) is soil-to-skin transfer different from different soilscontaminated at the same concentration?

Here, we present results for naphthalenecontamination of two soils with differentorganic carbon (OC) fractions (f

oc = 0.01 and

0.03). Soil samples were contaminated bydirect mixing with powdered neat naphthalene.After 48 hours, the partial pressure of naphtha-lene in the headspace above the soils becameconstant and did not change even after severalweeks, indicating equilibrium. Naphthalenepartial pressure at equilibrium increased withincreasing levels on contamination (C

soil) to a

maximum value, which is equal to the partialpressure from pure naphthalene. The mini-mum naphthalene concentration producing thepartial pressure of pure naphthalene representsan apparent saturation limit for the soil sample(Csat ). The effect of temperature on Csat (23,40, 50, and 60oC) was comparable to that forthe vapor pressure of pure naphthalene. Ab-sorption of naphthalene into silicone rubber, askin surrogate, equilibrated with contaminatedsoil was proportional to naphthalene partialpressure. Absorption rates into silicone rubberare also consistent with the partial pressuredata. These results suggest that vapor pres-sure may be a good indicator of availability fordermal absorption, at least for the soil con-taminants with significant vapor pressure.

Key words: dermal absorption, soil contami-nants, naphthalene

soil soil

P40

NICKEL INDUCES PLAS-MINOGEN ACTIVATORINHIBITOR-1 (PAI-1) EX-PRESSION TO INHIBITTHE FIBRINOLYTIC AC-TIVITY OF HUMAN AIR-WAY EPITHELIAL CELLS

1Angeline Andrew and 2Aaron Barchowsky,1,2Department of Pharmacology and Toxicol-ogy, Dartmouth Medical School, HB 7650Remsen, Hanover, NH 03755; 1Phone: (603)650-1964, 1E-mail:[email protected]; 2Phone:(603) 650-1673, 2E-mail:[email protected].

Pulmonary fibrosis is a serious debilitatingdisease caused by inhalation of certain types ofparticulate matter. Human epidemiologicaland animal studies have associated inhalationof nickel dusts with increased incidence ofpulmonary fibrosis. However, specific mecha-nisms for nickel-induced pulmonary fibrosishave yet to be elucidated. We hypothesize thatparticulate nickel promotes pulmonary fibrosisby inhibiting the fibrinolytic cascade. Sinceurokinase plasminogen activator (uPA) ini-tiates this cascade, this hypothesis was testedby examining the effects of non-cytotoxiclevels of nickel subsulfide on the balance ofuPA expression relative to expression of itsinhibitor, PAI-1, in cultured human bronchialepithelial cells (Beas-2B). Exposure to themetal decreased secreted uPA protein levelsand activity without affecting uPA mRNAlevels. In contrast, these same exposuresstimulated transcription of PAI-1, causingprolonged increases in both mRNA and proteinlevels. Despite partial recovery of uPA proteinlevels, uPA activity remained depressed formore than 48 h after exposure to nickel due tothe continued increase in PAI-1 expression.These data indicate that particulate nickelinhibits the fibrinolytic cascade by increasingthe ratio of plasminogen inhibitor to activator.Sustained loss of uPA activity may be a pri-mary mechanism contributing to nickel-in-duced pulmonary fibrosis in exposed popula-tions.


Key words: pulmonary fibrosis, nickelsubsulfide, fibrinolysis, respiratory distress,Beas-2B

supported by the X-ray diffraction data thatindicated the formation of pyromorphite uponP addition, which would reduce Pb solubility.The reduction in Pb bioavailability was evident3 days after treatment and no further reduc-tions were noted after 1 year of incubation.Adaptation of this technology to remediatelead-contaminated soils would eliminate theneed for soil excavation.

Key words: in situ stabilization, bioavailablePB, soil remediation

TRANSPORT OF METHYL-TERT-BUTYL ETHER(MTBE) IN UNSATURATEDSOIL

1Qizhi Zhang, 2Lawrence Davis, 1LarryErickson, 1Dept. of Chem. Eng., Kansas StateUniversity, Manhattan, KS 66506; 2Dept. ofBiochemistry, Kansas State University, Man-hattan, KS 66506; 1Phone: (785)532-5584,1Fax: (785)532-7372; 2Phone: (785)532-6124, 2Fax: (785)532-7278.

Transport of volatile organic compounds(VOCs) from soil into the atmosphere occursnaturally when volatile contaminants arepresent in unsaturated soil. MTBE transport inan experimental soil system was investigatedby measuring soil water concentrations atdifferent depths in the unsaturated zone andthe gas fluxes at the soil surfaces in plantedand unplanted chambers. Measured MTBEconcentrations at different depths demon-strated a non-linear relationship between thesoil water concentration and the depth. A one-dimensional transport model was developed tosimulate the transport processes of MTBE inthe unsaturated zone. An analytical solution tothe model equations is presented. Simulationsbased on this solution are compared with themeasured soil water concentrations and the gas

PostersContaminants in Porous Systems

Additional Presentations(Abstracts Received After Publica-

tion Deadline)

THE USE OF PHOSPHO-RUS AND OTHER SOILAMENDMENTS FOR INSITU STABILIZATION OFSOIL LEAD

Ganga Hettiarachchi and Gary Pierzynski,Department of Agronomy, Kansas StateUniversity, Manhattan, KS 66506.

In situ stabilization of Pb-contaminatedsoils can be accomplished by the addition of Pand other soils amendments. In situstabililization would have significant advan-tages over the standard remediation procedureof soil removal and replacement that is cur-rently used in residential areas. Five contami-nated soils having total Pb concentrationsranging from 1180 to 9000 mg/kg were used.Two long-term incubation studies showed asignificant reduction in bioavailable Pb (by thein vitro bioaccessibility test, also known asPhysiologically Based Extraction Test- PBET)upon addition of P (as triple superphosphate,phosphate rock, and H

3PO

4) and other soil

amendments in all materials tested. This is

Program OneWednesday, May 24, 2000Phytoremediation--Exudates andMetals


fluxes at the soil surface. The model gavereasonably good predictions for MTBE con-centration profiles within the unsaturated zoneand for gas fluxes of MTBE under steady stateconditions. Plants enhance the rate of trans-port of MTBE to the atmosphere by movingwater upward and by removing water from theunsaturated zone.

Key words: transport, MTBE, unsaturatedsoil, modeling, phytoremediation

decreased several-fold and methane was nolonger observable. Soil sampling indicatedthat high levels of DCE and some methaneboth were present in the fully saturated zone.The amount of methane is only a small fractionof the input TCE concentration. After fivemonths, the column was watered from the topwith Hoagland’s solution for two weeks andthen planted with successive crops of sunflow-ers. It was possible to observe transfer ofDCE into the stems of the sunflower plants, asreported elsewhere. Now after ~ one moreyear, no TCE is detectable in the top 20 cm ofsoil in the cylinder and surface flux rates ofDCE are only < 5% of the amount expected onthe basis of water use. This system appears tohave evolved into an effective remediationwithout intentional addition of any specificmicro-organisms. It is likely that the same soilcould do so in its natural setting, if bothanaerobic and aerobic zones were present.

Key words: trichloroethylene,dichloroethylene, natural attenuation,methanogenesis, methanotrophy

LONG-TERM MONITOR-ING TO OBSERVE NATU-RAL ATTENUATION INTHE LABORATORY

Lawrence Davis, Department of Biochemistry,Kansas State University, Manhattan, KS66506; Phone: (785) 532-6124.

Earlier studies in this laboratory reportedthe apparent degradation of several com-pounds supplied in groundwater to plantedchannels of alfalfa. However, it was notestablished whether the degradation processmight have occurred without plants or thenutrients and bacterial inoculant that wasintroduced to the channels at one point in theirlife history. Therefore, a cylinder of compa-rable depth was set up in September 1998 andfed with a low level of trichloroethylene. Thesoil was silty sand from near the closed RileyCounty Landfill, as used before. The watertable was maintained at a few cm from thebottom, producing a saturated zone close tothe soil surface. Surface flux rates of TCE andDCE (cis-1,2-dichloroethylene) were moni-tored as before by sampling vented containersplaced on, then pressed into, the surface of thesoil. No surface flux of TCE was measurable,even during the first few months; the dominantdetectable gas was DCE with some methane.After a further time, the surface flux of DCE

PostersPhytoremediation--Organics

PostersSorption, Binding, and Precipitation

ADSORPTION OF PB2+

AND ZN2+ ON PHOS-PHATE MODIFIED MAN-GANESE DIOXIDE SUR-FACES

1Hui Wang and Gary Pierzynski, Departmentof Agronomy, Kansas State University,Manhattan, KS 66506; 1E-mail:[email protected].

Sorption of Pb2+ onto manganese oxidesis an important mechanism for retardingmigration in soils, and bioavailability of Pb2+

can be decreased by the addition of P. Thisstudy was conducted to determine the role ofphosphate-modified manganese dioxide sur-face on the adsorption of Pb2+ in NaNO

3

solution. The effects of pH, Pb2+ concentration,


P concentration, and Pb:Zn ratio in the solu-tion were investigated in room temperatureand short-term equilibrium time, due to hy-pothesis that lead phosphates form and leadadsorption occur rapidly in aqueous systems.The study evaluated two manganese oxideswith different kinds of mineral structure,birnessite and cryptomelane. Significantsorption of Pb2+ by the phosphate-free oxidesample occurred at low pH level (near thePZC), indicating that the sorption was suffi-ciently energetic to overcome some electro-static repulsion. The adsorption edge increasedto higher pH as total Pb2+ concentrationincreased in solution. The phosphate-modifiedmanganese dioxide surface can enhance itscapability to retain Pb2+ and lowered theaverage pH of the sorption edge. A significantcorrelation was found between the zero pointof charge and the quantity of phosphate ap-plied to manganese oxide surfaces. The capac-ity of sorbed phosphate to lower the zero pointof charge depended on the mineral structure.Increasing the Pb:Zn ratio may also change thesorption edge to a lower pH, but the effectstrongly depended on the adsorption space onthe mineral surface. The phosphate-modifiedmanganese oxides may be useful for reducingsoil Pb2+ bioavailability and may improve thenew Pb2+ remediation method.

Key words: manganese oxides, sorbed phos-phate, electrostatic repulsion

James Botsford, Department of Biology, NewMexico State University, Las Cruces, NM88003; Phone: (505) 646-3726, E-mail:[email protected].

16

A SIMPLE, INEXPENSIVEAND RAPID METHOD TODETERMINE TOXICITYUSINGA BACTERIAL INDICA-TOR ORGANISM

PostersAnalytical Methods

This abstract is also scheduled for an oralpresentation on Tuesday, May 23, 2000 at 2:30p.m. under the session titled “AnalyticalMethods II,” which will be in the ParkerRoom. Please see page 11 for the abstracttext.


Index

Symbols

14C-pyrene 22

A

abiotic reduction 34acid mine drainage 51, 53adsorption 82advanced oxidation process 41aerobic 80agricultural byproducts 81air sparging 43Alcorn, Jessica 55alfalfa 9, 14, 24, 35, 63, 82alfalfa plants 29algae 14Allen, Shelley 3Alowitz, Michael 77Alvarez, Pedro 19, 65American Indian tribes 56ammonia 6ammonium bisulfate 16ammonium sulfate 16anaerobic 80anaerobic degradation 1anaerobic microbial reduction 84analysis 10Andersland, John 22, 47Anderson, Amy 37Anderson, J.A. 36, 74Anderson, Keith 54Anderson, Steve 54Andrew, Angeline 85animal waste lagoons 39Anitescu, G. 40anoxic 80anoxic/aerobic 8aquatic systems 72Armendariz, V. 80, 81Arnold, Robert 14arsenic 36, 77Arteaga, S. 23atrazine 19attenuation 43autoclaved prepared 45

B

Babcock, R.E. 16Bacillus 47Barbaris, Brian 14Barchowsky, Aaron 85

Barlow, Robert 22, 47Barranco Jr., Frank 33, 59barrier 63Barton, Larry 83Beas-2B 86Becker, J. Sabine 9Berkeley Pit Lake 53Berkeley Pit Lake System 51Berry, Laura 14Bess-Oberto, L. 80, 81Betterton, Eric 14Beyrouty, C.A. 46Bezbaruah, Achintya 6Bhadra, R. 26Bhandari, Alok 19, 82bi-phasic anaerobic digester 6Bielefeldt, Angela 4, 7, 17, 61binding 19, 83Bio-Sep 2bioaccessibility 30bioavailability 69, 82bioavailable PB 86biobarrier 39biobarriers 40biocidal 45bioclogging 39biodegradation 3, 25, 29, 41, 64biofilm 18, 39, 40biofiltration 81bioisolation 5biokinetics 5biological sulfate reduction 67BioLuxing 42biomass 2biomass density 2bioreduction 81bioremediation 4, 7, 30, 49, 53, 62, 68biosensor 60biosorption 12, 14biostabilization 62biosurfactant 47bioventing 59Bonola, Suzanne 64Botsford, James 11, 88Boyack, Leigh Ann 66Boyce, David 49Bradbury, Lorna 48brine 48brine-impacted soil 48Brown, Kevin 16brownfields 57Bryant, Natalie 22, 47BTEX 66Buchholz, R. 12Bukvic, Anamaria 73Bunge, Annette 84Bunke, G. 12


Burckhard, Suzette 28, 64, 70, 71Burgher, Karl 54

C

Caccavo Jr., Frank 20cadmium 14CAG 57calcium oxide 45Cameron, Douglas 52, 53Camp, Carl 2capture zone 42carbon tetrachloride 20Caruso, Joseph 9, 10Castro, Sigifredo 24catalysis 44catalyst 45Cathy, George 83CE separation method 9chemical modification 14, 81Chen, Benito 39Chen, Chen-Peng 84Chesnokov, Vladimir 44Cheung, Pui-Yi 65Chianelli, R.R. 23chiral 11chiral analysis 10chlorinated 32chlorinated hydrocarbons 79chlorinated solvents 42chlorination 45ChNPS 72chromate 34, 78chromium 35, 63chromium(VI) 81Chu, Shaogang 74, 75circulation cell 42citric acid 18closure plan 55COD 6column 62columns 82combustion 16communications 58community 58community outreach 68compacted clay liners 39compounds 11Connor, Steven 75constructed wetland 6, 37contaminant concentrations 46contaminated groundwater 1contaminated site 71contaminated soil 28, 29, 46, 64, 70conventionally prepared 45coordinating surface 21Cort, Todd 7

Cox, Timothy 43creosote bush 23Cunningham, Al 20, 39cytochrome P450 68

D

da Silva, Marcio Busi Luis 65Dai, Dongping 32, 33Das, Neema 60Davalos, Hugo 38Davis, Andy 36, 51, 55, 74Davis, Cynthia 59Davis, Lawrence 24, 29, 86, 87Day, Jason 9decision making 71decisions 32DeCurnou, P. 55defluoridation 31degradation 59dehalogenation 8dehydrohalogenation 44deicer 25deicing fluid 18denitrification 6denitrifier 8derivatization 76dermal absorption 85Dewan, C. 48Di Julio, Shoeleh 42dichloroethylene 87diesel 59Dietz, Annette 68Dietze, H.J. 9dimension 32Dimsha, Mark 83dissolution 32, 33, 59, 61, 62DNAPL 62DOE 56Dokken, K. 9, 14, 34, 62, 80, 81Donnelly, K.C. 84Drucker, Andrew 42Duncan, Kathleen 1, 2

E

ecological recovery 30ecological risk 51EDTA 22, 47Ela, Wendell 14electrochemical peroxidation 75electrostatic repulsion 88Elmore, Andrew Curtis 41enantiomer 11encapsulation 38endpoints 33environmental justice 56environmental remediation 68


EPA 16, 50, 52, 54, 56Erickson, Larry 24, 28, 29, 46, 70, 71, 82, 86erosion 48esterification 80ethanol 66Ewing, John 32EXAFS 14, 35, 63explosives 27extraction 30

F

Fang, Fu 75fate 27fate and transport models 50Fennemore, G.G. 36, 74Fenton’s Reagent 75fibrinolysis 86Flanigan, Virgil 16Fleischman, Jeffrey 42Fletcher, John 29fluidized-bed bioreactor 8fluoride 31fluorosis 31Flynn, Patrick 49foam 43Folkes, David 57, 63formaldehyde 26formation 35fracture 59furfural 10

G

Gamez, G. 8, 9, 14, 34, 62, 81Gander, Jerry 78Garcia, S.S. 84Gardea-Torresdey, J.L.

8, 9, 14, 23, 30, 34, 62, 80, 81gas condensate hydrocarbons 1gasoline 16GC/MS 74genotoxicity 84Gentry, T.J. 46Gerlach, Robin 20Gettler, Ryan 77GFAAS 9Ghosh, Suman 5Gilcrease, Patrick 66Ginner, Jennifer 19Githinji, Maina 79glycol 25gold 9, 14Gomez, E. 23Gomez, Katherine 69green rust 34groundwater 32, 37, 43groundwater circulation well (GCW) 42

groundwater flow 75GUI 71Gustafson, David 70

H

Hale, Kerry 24, 73halogenated 45Harmon, Steve 1, 2Harris, Thomas 37, 48Hasan, Syed 5heavy metals 12, 74, 80, 81Helgen, S. 55Hellman, Jason 41Herrera, I. 9, 14, 34, 62, 81Hettiarachchi, Ganga 86Hill, Stuart 56Honeyman, Bruce 18Hong, Chia-Swee 74, 75Houston, Lorrie 2Huang, Yong 21Hughes, J.B. 26humidity 76humification 83Hunt, Craig 65Huntington, John 10Hurtado, R. 30hydraulic fracturing 42hydrocarbon spill 2hydrogen peroxide 80hydrophobic soils 49hydroxyapatite 82hyperaccumulation 22, 47

I

IAAP 26Illangasekare, Tissa 4, 17, 32, 33, 58, 59, 60, 61immobilization 12, 60in situ stabilization 86inhibition 7involvement 58ion-selective 31iron 78iron reactive barriers 79iron-reducing bacteria 20Isleyen, Mehmet 76isotherms 19isotope ratios 9

J

Jennings, Eleanor 47jet fuels 29Jiang, Shaoyi 35Johnson, Kathy 19Jonas, Jim 52Ju, Xiumin 14Just, Craig 25


K

Kantar, Cetin 18Kapila, Shubhen 16Karthikeyan, R. 29Kathikeyan, R. 28Kerr, Karen 14kinetics 3, 7Kinkle, Brian 65Kinoshita, Charles 67Klabunde, John 45Klabunde, Kenneth 44, 45Klein, Mike 33Klimmek, Dipl.-Leb.-Chem. S. 13Knightes, Christopher 3Kojouharov, Hristo 39Kolhatkar, Ravi 1, 2Komlos, John 39Kramer, Barbara 30Krutz, L.J. 46Kulakow, Peter 28, 46, 64, 70, 71Kurz, David 31

L

landfarming 49, 50landfill leachate 6lanthanide oxide formation 9LaPlante, Rosanna 17leaching 36lead 14, 22lead pyromorphite 82Lee, Wen-yee 11Lesan, Heather 19Leven, Blase 28, 64, 70, 71Liske, Yvonne 16LNAPL 61, 62Lorbert, Steve 16Lovanh, Nanh 65

M

Macalady, Donald 84Mackay, W.P. 23magnesium oxide 45magnetite 21Mahaffey, William 42manganese oxides 88Mankin, K.R. 28, 29Marchin, George 45Mark, Sandra 48Mauldin, Denton 33, 59McGahee, Joseph 58Medicago sativa 24Medine, Gavin 44Meiggs, Theodore 42metabolism 27metal binding 14, 35, 63

metal oxide 44, 45metal valence 36metals 24, 38, 84methane recovery 6methanogenesis 87methanotrophy 87MgO 44microalgae 12microbial populations 2Mikhyeyev, Oleksandr 72mine drainage 37mineralization 41Mishakov, Ilya 44Mitchell, Paul 37Mitman, Grant 51, 53mixture-based model 41mixtures 3, 84modeling 5, 63, 82, 87models 33, 40MODFLOW 42molecular modeling 35molybdenum 73monitoring 43Moore, Quentin Robert 60Morrison, Kendra 4MTBE 28, 64, 66, 74, 75, 87multi-species 39multi-phase 33multi-substrate 3Mulukutla, Ravichandra 45Murphy, Thomas 49mycobacteria 65

N

Nam, Paul 16nanocrystalline 44nanoparticles 44, 45nanostructure 45naphthalene 85NAPL 5, 33, 43, 59Narang, Rajinder 74Narayanan, Muralidharan 70, 71natural attenuation 66, 75, 87nickel 14nickel subsulfide 86nitrate 6, 20, 78nitrate reduction 21nitrification 6nitrite 20nitroaromatics 20numerical 33nutrification 51

O

oats 80, 81oilfield waste disposal 49


Olson, Paul 29organic carbon 52, 54Orrostietai, V. 37Oswal, Namita 5oxidation 4oxygen 69

P

PAH 3, 4, 5, 62, 65, 74Parkin, Gene 78Parsons, J.G. 8, 9, 14, 23, 34, 62, 81passive treatment system 37PCB 40, 76PCP 4pentachlorophenol 7pentafluorobenzoyl chloride 76Peralta, J.R. 23perchloroethene 15permeability 39permeable reactive barriers 20peroxidase 83pesticide 19pesticides 11, 30Peters, Catherine 3petroleum 75petroleum hydrocarbons 28, 29, 46, 64, 69, 70, 71petroleum production 48petroleum-contaminated soil 46pH 21phenols 83photocatalysis 74, 76phytochelatins 24phytofiltration 14, 80phytophotolysis 26phytoremediation 22, 23, 24, 25, 27, 28, 29, 30,

46, 47, 64, 68, 69, 70, 72, 73,74, 87

Pierzynski, Gary 28, 86, 87Pilon, Marinus 24Pilon-Smits, Elizabeth 24, 73Pingitore, N.E. 23, 34, 62Pirkl, Dan 64pit lake 51, 52plant invasion and succession 30polycyclic aromatic hydrocarbons (PAHs) 30Ponce de Leon, C.A. 10poplar 68, 69porous media 18PRB 63, 78predictive analysis 51Prokhnevsky, Alexey 72Pseudomonas 47public health 31pulmonary fibrosis 86Putnam, R. 76pyrite oxidation 75pyromorphite 35

R

radioactive waste 54radioisotopes 59radionuclides 72Ramaswami, Anu 4, 27, 61, 64, 76RAMP 54Randerath, K. 84Rascon, A.E. 80Rascon, E. 23RDX 26Reardon, Kenneth 3, 40, 60recharge zone 42recovery 35, 63Reddi, Lakshmi 38Reddy, Jai Bharath 70redox 36redox potential 52reduced-iron minerals 34reduction 78reductive dehalogenation 15remediation 33, 40, 43, 59, 82Rentz, Jeremy 68residential 32, 58residual 61respiratory distress 86respirometry 59Reynolds, C.M. 46Rhizobium meliloti 11rhizosphere 64Richard, Rock 61Richards, Ryan 44risk 32Robertson, Shelly 66Rodolph, G. 37root exudates 22Roschet, W.A. 37Rubin, Ellen 27Ruchko, Mikle 72Ryan, P. Barry 30

S

Saba, Tarek 32, 33Sahi, Shivendra 22, 47salinity 48Salvador, James 11Samorano, Daniel 14sand (quartz garnet, ilmenite, hematite, magnetite 80saturation 32Schaefer, Vernon 28, 64, 70Scherer, Michelle 19, 34, 77, 78Schnoor, Jerald 25Schnoor, Jerry 68Schwab, A. Paul 28Scott, Kenneth 63seasonal turnover 52


seepage 36Segar Jr., Robert 8, 79selectivity 45selenium 10, 24Sesbania 22, 47Shanks, J.V. 26Shann, Jodi 21, 69, 73Sharp, Robert 39Shevade, Abhijit 35Shi, Zhiao 82Sigler, Lisa 57silica 38silver 82Simonton, Scott 83simulation 32simulations 40Sipple, Jefrey 76sludge 50, 55sludge treatment 2soda ash 67sodium bicarbonate 67soil 4, 19, 30, 83, 84soil contaminants 85soil contamination 23soil remediation 86soil vapor 15soil-water transport 71Solanum elaeagnifolium 81solid media 24solvents 76sorbed phosphate 88Sorochinsky, Boris 72Spanggord, R.J. 26stability 35, 84stabilization 38Stack, Steven 73Stan, Prof. Dr. rer. nat. H.-J. 13Stansbury, John 6Stark, Phillip 10stripping agents 35, 63Sublette, Kerry 1, 2, 48substitution 35subsurface 39subsurface barrier 20subsurface drainage 48subsurface flow 37sulfate-reducing bacteria 37sulfur 16sulfur dioxide 44Sullivent, K. 48supercritical extraction/oxidation 40Superfund 56surface complexation 18surfactant 7, 61, 65Sylva, Traci 67

T

TAG 57tank bottoms 49Tanner, Ralph 47Tapp, J.B. 48Tavlarides, L.L. 40Tawachsupa, Santhiti 76technology assessment 33temperature 61Terry, Norman 24tetrachloroethene (PCE) 8, 80TGGE 65Thoma, G.J. 46Thoma, Greg 1Thompson, Kipp 28, 70Thomson, Bruce 83Tiemann, K.J. 8, 9, 14, 23, 34, 62, 80, 81Tiemman, K.J. 80titanium dioxide (TiO2) 74, 76toxicity 11transport 32, 87transport modeling 18treatment 38Trent, Gary 1triazole 25trichloroethene (TCE) 8, 80trichloroethylene 39, 68, 87tungsten 73

U

unsaturated soil 87uptake 74uranium 18

V

van Genuchten model 71van Middlesworth, J. 55vegetation 28, 29, 46, 64, 70Vestal, Eric 4VOCs 43, 76Vogler, Ken 33, 59Volodin, Alexander 44

W

Wang, Hui 87Wang, Lei 8, 79waste disposal 50waste rock dumps 36, 75water chemistry 52water quality 54water treatment 77Waterman, Erna 54weak cation exchanger 82wetlands 26, 27wheat 80


Wilke, A. 12Willett, Margery 52, 53Williams, Aaron 34Wolf, D.C. 46

X

x-rays 59XANES 14, 35, 63, 81XAS 23XRMF 23Xu, Fangxiang 82

Y

Yacaman, M.J. 14Yates, Rick 1, 48Yorke, C. Alvin 42Yoshitomi, Ken 21

Z

Zea mays 22Zeeman 9zero-valent iron 20, 21, 77Zhang, Qizhi 86Zhang, Tian 6, 21Zhou, G.-D. 84Zhou, W. 40Zhu, Yong Liang 24Zimbron, Julio 40zinc 14

program one tuesday, may 23, 2000 ... - engg.ksu.edu

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