molecular characteristics and differences of effluent organic matter from parallel activated sludge...

Molecular Characteristics and Differences of Effluent Organic Matterfrom Parallel Activated Sludge and Integrated Fixed-Film ActivatedSludge (IFAS) ProcessesLinda Y. Tseng,† Michael Gonsior,‡,* Philippe Schmitt-Kopplin,§,∥ William J. Cooper,⊥,# Paul Pitt,▽

and Diego Rosso⊥,#

†Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-1593, United States‡University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, Maryland20688, UnitedStates§Helmholtz Zentrum Munich, German Research Center for Environmental Health, D-85764 Neuherberg, Germany∥Chair of analytical Food Chemistry, Technische Universitat Munchen, D-85354 Freising-Weihenstephan, Germany⊥Department of Civil and Environmental Engineering, University of California, Irvine, California 92697-2175, United States#University of California, Urban Water Research Center, Irvine, California 92697-2175, United States▽Hazen and Sawyer, P.C., 498 Seventh Avenue, New York, New York 10018, United States

ABSTRACT: A direct comparison between parallel activated sludge andintegrated fixed-film activated sludge (IFAS) processes was performed in thisstudy because both treatments received the same primary effluent, althoughdifferences may still remain due to different return flow rates. Modernultrahigh resolution electrospray ionization Fourier transform ion cyclotronresonance mass spectrometry was applied to characterize the complexity ofeffluent organic matter (EfOM) and to evaluate both processes in their abilitiesto change the EfOM molecular composition. At different stages during the twoprocesses a direct comparison of the performance and changes in molecularcomposition of the IFAS with those of the activated sludge was undertaken.Large differences in the molecular composition between both processes wereonly apparent in the early stage of the aeration cells and the first cell of theIFAS possibly due to the higher flow rate and a delay in aerobic bacterialdegradation. Despite the double flow rate (0.263 m3 s−1) in the IFAS reactors compared to the activated sludge, by the end of thetreatment the EfOM composition of both processes were undistinguishable from each other. However, a much more complexEfOM was generated in both processes, suggesting that bacteria are responsible for an increase in molecular diversity in theeffluent.

■ INTRODUCTION

A detailed chemical analysis of wastewater effluent is intrinsic tothe understanding of chemical dynamics and treatmentefficiency.1 Since the late 1990s, the electrospray ionizationFourier transform ion cyclotron resonance mass spectrometry(ESI-FT-ICR MS) technique, though cost-prohibitive for manyenvironmental applications,2 has made great strides inidentifying thousands of molecular formulas in aquatic naturalorganic matter (NOM).3−7 However, most chemical character-ization of complex organic matrices to date has focused onNOM in natural environments8−10 and chemical character-ization studies related to engineered water systems also focusedmainly on NOM and its effect during water treatment processand on the resulting drinking water quality.11−15 Recently astudy demonstrated the versatility of FT-ICR MS as atechnique that can provide a detailed chemical characterizationof wastewater treatment effluent organic matter (EfOM) 1

The chemical composition of EfOM was thought to besimilar to NOM.16 However, compounds such as syntheticorganic compounds and soluble microbial products found inEfOM were reported to be chemically distinct fromNOM.1,17,18 It has previously been shown that even bulkproperties of EfOM such as spectrophotometric properties,molecular weight, dissolved organic carbon (DOC), and totaldissolved nitrogen (TDN) concentrations are different fromthose of NOM.18−23 Although these bulk properties andselected chemical species have been studied extensively,24,25

there is a lack of information on the complex composition ofEfOM. Detailed characterization of EfOM has the potential toelucidate the chemical diversity in EfOM, thus it can act as a

Received: January 17, 2013Revised: August 7, 2013Accepted: August 13, 2013Published: August 13, 2013

Article

pubs.acs.org/est

© 2013 American Chemical Society 10277 dx.doi.org/10.1021/es4002482 | Environ. Sci. Technol. 2013, 47, 10277−10284

pubs.acs.org/est

measure to compare EfOM from different sources and to giveindications of potential selective removal of chemical speciesand of the overall wastewater treatment performance. With theadvancements of analytical technology, a more comprehensivechemical characterization of EfOM is now possible.The nontargeted ultrahigh resolution ESI FT-ICR MS

analytical approach allowed mass spectrometric analysis ofcomplex mixtures such as EfOM.1,26 This technique is capableof assigning unambiguously thousands of molecular formulas toultrahigh resolution mass peaks and can therefore be used toevaluate the chemical makeup of complex mixtures of organicmolecules.Samples from two parallel and independently operating full-

scale processes treating the same wastewater were analyzed inthis study. These side-by-side trains featured the activatedsludge process (ASP) and the integrated fixed-film activatedsludge (IFAS) system. The IFAS system was an evolution ofthe ASP where media were added to provide surface for biofilmgrowth.29 The resulting process operated with an increasedbiomass inventory thanks to the combination of suspended andattached biomass, and was able to sustain higher loading rates(gLOAD m−3 h−1, where load is both biodegradable chemicaloxygen demand, or bCOD, and NH4

+) and higher oxygenuptake rates (gDO m−3 h−1).27 There were several advantages toenhance ASP with the introduction of biofilm, such as smallerphysical footprint,28 enhancement of nitrification in wastewatertreatment, longer solids residence time29 typically associatedwith increased process stability,40 and increased removal ofanthropogenic compounds from the water phase.41 Thereforethese biofilm-based systems have gained increasing interest fordomestic wastewater treatment.28−31 Because both the IFASand ASP trains in the studied wastewater treatment plantreceived the same wastewater influent, this situation wasadvantageous for a comparison of the chemical composition ofEfOM and the differences in process performance.Previous analyses of the chemical oxygen demand (COD)

removal in the secondary treated effluent of both trains showedremarkably similar values suggesting a very similar performanceof the two different treatment trains.27 Accordingly, the goal ofthis study was to characterize and directly compare the EfOMfrom the IFAS and the ASP treatment processes to evaluatewhether the chemical diversity was similar during bothprocesses and in their effluents. Since each train was composedof several individual well-mixed reactors in series (Figure 1), aside-by-side comparison of these reactors was evaluated

sequentially in each train for any potential change of thechemical diversity of EfOM.

■ MATERIALS AND METHODS

Process Conditions. The T.Z. Osborne Water Reclama-tion Plant is owned and operated by the City of Greensboro,NC. In this facility two tanks were selected for testing: Tank 11was operated as strict activated sludge in Ludzack-Ettingermode; Tank 12 was operated as hybrid IFAS/ASP, since thefirst half of its volume was converted to a large-scale pilotdemonstration of the IFAS technology (IFAS media byAnoxKaldnes). The two tanks were fed the same primaryeffluent, and were parallel and independently operated withseparate clarifiers thus separate return activated sludge (RAS)streams (Figure 1). The aeration system for the ASP cells inboth processes used Sanitaire fine-pore disc diffusers, whereasthe IFAS reactors were retrofitted with coarse-bubble nozzles.The surface of the IFAS reactors was continuously sprayed withsecondary effluent to minimize the accumulation of foam.This large wastewater treatment plant treats an average flow

of 1.75 m3 s−1 and at the time of sampling (beginning of thesummer season) the process was operated in ordinaryconditions (primary effluent total COD and NH4−N were337 mg L−1 and 15.0 mg L−1, respectively) meeting effluentlevels of total COD of 28.6 mg L−1 (Tank 11, ASP) and 28.2mg L−1 (Tank 12, IFAS) and of NH4−N below 0.2 mg L−1

(Tank 11, ASP) and below 0.1 mg L−1 (Tank 12, IFAS).Sample Collection. A grab sample of mixed liquor was

collected using a sampling pole approximately 1 m away fromthe wall of each reactor cell and 0.5 m below the surface.Reactor cells were well-mixed (the operating air flow rate farexceed the requirements for a well-mixed reactor, and theapparent superficial liquid velocity was of the order of 1 m/s),therefore each single grab sample was assumed to berepresentative of each reactor volume. At the time of sampling,the aggressive defoaming spraying at this facility has reduced toa negligible extent the foam accumulation in the IFAS reactorsthereby reducing the possibility of chemicals differentiallyaccumulating onto the floating foam. The grab samples fromthe IFAS cells were treated like the grab samples from otherreactor cells, since only the liquid portion of each sample wasused for analysis. Each sample was filtered on-site with aFisherbrand 0.2 μm syringe filter containing mixed celluloseester (MCE) membrane. The samples stored in Nalgenepolypropylene copolymer (PPCO) bottles with polypropylene

Figure 1. Process layout. Tank 11 is strict activated sludge (ASP, receives a flow of 0.131 m3 s−1) and Tank 12 is a hybrid of integrated fixed-filmactivated sludge in tandem with activated sludge (IFAS/ASP, receives a flow of 0.263 m3 s−1). Tank 11 and Tank 12 have separate secondary clarifiertherefore separate return activated sludge (RAS).

Environmental Science & Technology Article

dx.doi.org/10.1021/es4002482 | Environ. Sci. Technol. 2013, 47, 10277−1028410278

cap were immediately shipped to the laboratory for extraction(sample storage time not exceeding 24 h).Sample Preparation. An aliquot of 200 mL of each 0.2 μm

filtered sample was acidified to pH 2.0 with small amounts ofconcentrated HCl (puriss. p.a., ≥32%, Sigma Aldrich) and thengravity-fed through an Agilent Bond Elut solid-phase extraction(SPE) cartridge filled with 1 g of styrene-divinylbenzenepolymer (PPL) resin. Prior to the extraction, the solid-phaseresin was conditioned by passing 5 mL LC-MS grade methanol(Chromasolv, Merck) through the cartridge followed bywashing off the methanol using acidified (pH 2) LC-MSgrade water (Chromasolv, Merck). Following the extraction,the cartridge was washed with 5 mL acidified LC-MS gradewater and then dried under pure N2 gas. The extract was theneluted from the cartridge with 2 × 5 mL LC-MS grademethanol and stored at −20 °C thereafter for subsequentanalyses. To calculate the extraction efficiency, a 20 mL aliquotof the samples before and after passing through the cartridgewas collected for dissolved organic carbon (DOC) analysis.Dissolved Organic Carbon (DOC) Analysis. DOC

concentrations were measured using a high temperaturecombustion Shimadzu 5000A TOC Analyzer. Each standard(potassium hydrogen phthalate) were measured in triplicates,and all standards and samples were acidified to pH 2.0.FT-MS Analysis. All solid-phase extracted EfOM samples

were diluted 1:100 with methanol and then analyzed at theHelmholtz Zentrum in Munich, Germany using a Bruker ApexQE 12 T FT-ICR mass spectrometer. Singly charged andunfragmented negative ions were generated at atmosphericpressure within an Apollo II Electrospray ionization (ESI)source at a flow rate of 3 μL min−1. Detailed information aboutthe ESI-FT-ICR-MS method applied in this study is givenelsewhere.32 The spray stability and ionization efficiencies wereoptimal using 100% methanol and did not improve whendiluted with water. We purposely did not add any ammoniumhydroxide because it did not help to improve the signal.Molecular formula assignments were based on the following

elements: 1H, 12C, 16O, 14N, 32S. The isotopes 13C and 34S werealso included to cross-validate assigned molecular formulas.The same calibration procedure used in a previous study ofEfOM were used 1 and a mass accuracy of 0.2 ppm wasachieved.

Visualization of FT-ICR MS data was undertaken using VanKrevelen diagrams33 and a previously developed modifiedKendrick plots referred to as KMD-Z* plots.34 In this diagramthe ratio of the Kendrick Mass Defect (KMD, eq 1) and theparameter Z* (eq 2) are plotted against the exact masses of allassigned molecular formulas to be able to directly showunambiguous homologous CH2-series.

= −KMD nominal mass(NM) KM (1)

where NM = nominal mass of the compound, that is, molecularweight strictly rounded to the next integer value [Da]

= ×KM mass (14.0000/14.01565)measured (2)

* = × −Z modulus (NM/14) 14 (3)

This approach also allows spreading the data points along they-axes (KMD/Z*) and shows in more detail the molecularweight-dependent differences between samples. The ratio ofKMD/Z* produced an almost unambiguous indicator forhomologous series based on CH2. On rare occasions the samevalues can be produced but are located at different masses andtherefore homologous series are practically unambiguous in theproposed diagram where this ratio is plotted against the exactmass of the assigned neutral molecules. This KMD/Z* diagramis much more informative when compared to traditionalKendrick diagrams.35 More details about why two independentparameters are needed to assign unambiguous homologousseries and about the above-mentioned parameters were given inan earlier study.6

Only masses that had a minimum of 1% relative abundanceand had a correspondent 13C isotope were considered in thisstudy. The reproducibility of the FT-MS spectra acquired usingthe same instrument has been demonstrated in a previous study34 and replicate samples showed only small differences that canbe explained by very small intensity mass peaks that are justunder or just above the signal-to-noise ratio. A directcomparison between samples was therefore possible.

■ RESULTS AND DISCUSSIONElectrospray ionization is very sensitive to salt and in mostcases a desalination step is required prior to mass spectralanalysis. Here we used solid phase extraction and a polymeric

Figure 2. Dissolved organic carbon (DOC) concentrations and solid-phase extraction (SPE) adsorption efficiencies in cells of Tank 11 (ASP) andTank 12 (IFAS). Note: PE = primary effluent and SE = secondary effluent.



resin (PPL) that has been shown to have the highest overallextraction efficiency for DOM over a broad polarity range.However, PPL still has its limitation, and varying DOMrecoveries from PPL are possible based on the makeup of theinitial DOM present in any given sample.In general, the adsorption efficiencies of the used SPE were

high, with values in the range 75−85% of DOC retained for allactivated sludge cells and secondary effluents (SE) in Tank 11and Tank 12 (Figure 2). An exception was the primary effluent(PE) with an adsorption efficiency of 34%. The low adsorptionefficiency of the PE may be explained by a possibly elevatedabundance of highly hydrophilic, relatively short-chain organicacids (e.g., CH3CH2COOH) typically found in PE36−38 which

would not be efficiently retained by the solid-phase resinemployed for extraction. Additionally, the common practice ofadding coagulants in preliminary operations and primarytreatment effluent for odor control or to enhance CODremoval in the primary settler may play a role, since thecoagulant would preferentially remove organic matter thatwould be otherwise easily retained during SPE. The anoxicdenitrification cells of Tank 11 (i.e., Cells A−C) hadprogressively increasing adsorption efficiencies of 62% in CellA to 72% in Cell C, whereas the anoxic denitrification Cells A-C of Tank 12 had more consistent adsorption efficienciesoscillating around 80%. Although the adsorption efficiencies ofTank 11 and Tank 12 seem to have different trends for the

Figure 3. Direct comparison of van Krevelen and modified Kendrick plots (KMD-Z* plots) of SPE-DOM samples collected in cell D and I, Tank 12,and Tank 11, respectively. The size of each symbol is proportional to the intensity of the peak from the FT-MS data.



initial samples in the profile (PE and Cell A in Figure 2), theDOC measurements were single measurements, and thus theseefficiency trends may be within the errors of the extraction andmeasurement. Replicates are needed in future studies to showwhether there are in fact different adsorption and extractionefficiencies for such parallel process configurations, or if theapparent trends are an artifact driven by an erratic sample (i.e.,Cell A in either tank, Figure 2). Nonetheless, the highadsorption efficiencies for activated sludge cells are evidence toconclude that the SPE procedure employed in this study is asatisfactory choice to extract activated sludge dissolved organicmatter, but it is of limited applicability for the PE if high DOCrecoveries are important. It should be noted here that theadsorption efficiencies given here are not representing trueextraction efficiencies because a small percentage of veryhydrophobic compounds may not completely elute from theresin using methanol and hence the actual recovery of EfOM isnot known. However, the reproducibility of recovered EfOM ishigh as demonstrated in a previous study using diverse EfOMsamples from biogas reactors.34

Despite the doubled process flow which halved the hydraulicretention time in the IFAS treatment, the effluent DOC fromboth the IFAS and ASP processes had very similar values of 8−9 mg L−1 (Figure 2). Furthermore, the molecular complexityand chemical diversity of EfOM tracked using FT-MS showedthat the effluents from the different treatments with differentflow rates were very similar suggesting that both treatments(ASP and IFAS/ASP) have similar effects on the moleculardiversity of EfOM (Figure 3). Moreover, Figure 4 showsconsistent molecular diversity for Tank 11 SE and Tank 12 SE.However, significant differences in the chemical diversity werefound in cell D between the IFAS (Tank 12) and the ASP(Tank 11) (Figure 3). These differences in absolute values(appearance of mass peaks) may be explained by reducedtreatment efficiency of transforming organic matter in the earlystage of aeration due to the doubled flow in the IFAS Tank 12or the still inefficient release of higher molecular weight organicmatter by aerobic bacteria. After the third IFAS reactor (Cell F

in Tank 12), the molecular diversity (molecular formulasassigned) in the IFAS and the ASP was virtually identical(Figure 3) indicating that the residence time in the three IFAScells was sufficient to yield similar organics treatment whencompared to the ASP. It is important to recognize that therelative abundance of mass peaks and assigned formulas inFigure 3 is not a quantitative indicator. Yet, the intensityshowed evidently that the grouping of organic compounds wasmore similar between Cell I of Tank 11 and Tank 12 thanbetween Cell D of both tanks suggesting similar EfOM qualityafter both treatments. A hierarchical cluster analysis based ondistance measures of dissimilarity using Pearson correlation(R2) and averaged linkages between groups also demonstratedthe differences in relative abundances and in appearance ofmass peaks and associated molecular formulas between Cell Dof Tank 12 (start of IFAS) and the rest (Figure 5). The resultof the hierarchical cluster analysis showed similarities betweenTank 11 Cell C and Tank 12 Cell A (Figure 5). This againsuggested that the doubled flow rate in Tank 12 might have

Figure 4. Direct comparison of van Krevelen and modified Kendrick plots (KMD-Z* plots) of SPE-EfOM in combined primary and the twoseparate secondary effluent samples present in Tank 11 and Tank 12, respectively.

Figure 5. Hierarchical cluster analysis of EfOM molecular complexityof all treatment cells in both independent tanks. Note: Calculationswere based on average value per group and using R-squaredcorrelation.



reduced the treatment efficiency in the beginning, but thesimilarity between Tank 11 SE and Tank 12 SE confirmed thatthe EfOM after both treatments was practically identical.An important finding was that the overall molecular diversity

increased drastically within both treatment tanks stronglysuggesting that the bacterial biomass released a high degree ofcomplex dissolved organic matter with higher molecular weighteven though the DOC and biochemical oxygen demand(BOD) were removed in an expected fashion. The number ofassigned molecular formulas with associated mass peaks ofrelative abundances higher than 1% increased from 987 in CellD of Tank 11 (ASP) to 1387 in Cell I of the same tank (Figure3). In Tank 12 (IFAS), the number of formulas increased from669 in Cell D to 1411 in Cell I indicating approximately a 50%increase in molecular diversity in Tank 11 and a 100% increasein Tank 12, respectively. Additionally, a significant increase inhigh molecular weight mass peaks and associated molecularformulas were observed between Cells D and I in both tanks(Figure 3). Even with the presence of already high molecularweight organic compounds in Tank 11 Cell D (Figure 3), themolecular diversity continued to increase in the following cells.The increase in molecular diversity of organic molecules alsoindicated that bacterial biomass produced/released complexand highly transformed organic compounds. Because of therelatively low molecular diversity of PE (Figure 4) and the lowextraction efficiency of the intake, it can be concluded that thedrastic increase in chemical diversity of hydrophobic highmolecular weight organic compounds was directly associatedwith the bacterial biomass. Figure 4 demonstrates the markedtransformation of PE organic matter by bacterial biomass to theorganic matter in SE of both tanks.The possible release of refractory DOM by bacteria has

fueled debates in the biogeochemical community in recentyears after the proposed concept of the microbial carbon pump(MCP).42 The concept takes into consideration that refractoryDOM is supplied to the deep ocean via bacterial transformationand it was partially based on studies were refractory DOM wasformed after bacterial incubation.43 Our study showed that lowBOD and high molecular weight DOM is produced throughoutthe ASP process supporting the foundation of the MCPconcept and suggesting that refractory EfOM is formedthroughout the treatment process.Another surprising observation was that a higher order of

chemically similar formulas was found at later stages of the ASPand IFAS treatment which are analogous to higher orders andhomologous series found in NOM.33,39 For example, theappearance of longer homologous series (i.e., series with thesame KMD/Z* value) based on an exact difference of CH2-groups throughout the entire molecular weight range (200−600Da) was much more pronounced in the last cells (Figure 3). Itseemed that the processes within the ASP and IFAS resemble ahigh degree of production and rearrangement of organic matterthat resulted in the observed highly symmetric pattern (smoothextent of symmetric pattern around each nominal mass) acrossthe molecular weight range and distinctly longer homologousseries.In a previous study, a large diversity of linear alkyl benzene

sulfonates (LAS), their co- and byproducts including allpossible homologues were present in a secondary treatedeffluent.1 The FT-MS data presented in this study also showedthe same high intensity homologous series suggesting that thesespecific sulfonates resembled an important component ofEfOM throughout the ASP treatments. There were numerous

high-intensity peaks likely arising from aliphatic sulfonates inthe PE with H/C ratio >2 and O/C ratio in the low to mediumrange (Figure 4). These high-intensity peaks disappeared inTank 11 and Tank 12, suggesting degradation and trans-formation. Furthermore, by tracking the intensities of ahomologous series of aromatic sulfonates through the process,transformations of one class of sulfonates to another (i.e.,dialkyl tetralin sulfonates, DATS, transform to dialkyl tetralinsulfonate intermediates, DATSI) were observed (Figure 6).

This study focused on the characterization and moleculardiversity of the DOC from the IFAS and ASP. The increase ofmolecular complexity and diversity in the EfOM of the IFASand ASP suggested that bacterial biomass produced/releaseddiverse and hydrophobic organic compounds with highmolecular weight, and they were highly reworked and hadhigher orders and longer homologous series. In line with aprevious study,1 the FT-ICR-MS data also showed LAS andtheir co- and byproducts as important components of EfOMduring the treatment processes and were likely to be highlyrearranged sulfonates via transformation and degradation. Theresults presented in this study suggest FT-ICR MS as apromising tool for comparing the EfOM from differenttreatment processes. Further studies are needed to investigateDOC extraction efficiency of replicates using SPE to addressthe extraction trend along wastewater treatment trains.

■ AUTHOR INFORMATION

Corresponding Author*Phone: +1 410 326 7245; e-mail: [email protected].

NotesThe authors declare no competing financial interest.

■ ACKNOWLEDGMENTS

We gratefully thank the T.Z. Osborne Water ReclamationPlant’s personnel coordinated by Donald Howard for their helpduring sampling and data collection. This research wassupported by Hazen and Sawyer, P.C. and is contribution4794 from the University of Maryland Center for Environ-mental Science, Chesapeake Biological Laboratory.

Figure 6. Trends of averaged intensities of all mass peaks associatedwith DATS and DATSI-type molecular formulas along the treatmenttrains from primary effluent (PE), across the ASP/IFAS-ASP (Cell Dto Cell I) toward the secondary effluent (SE). Note: No DATSI-typeassociated mass peaks were found in PE.



mailto:[email protected]

■ REFERENCES(1) Gonsior, M.; Zwartjes, M.; Cooper, W. J.; Song, W.; Ishida, K. P.;Tseng, L. Y.; Jeung, M. K.; Rosso, D.; Hertkorn, N.; Schmitt-Kopplin,P. Molecular characterization of effluent organic matter identified byultrahigh resolution mass spectrometry. Water Res. 2011, 45 (9),2943−2953.(2) Reemtsma, T. Liquid chromatography-mass spectrometry andstrategies for trace-level analysis of polar organic pollutants. J.Chromatogr., A 2003, 1000 (1−2), 477−501.(3) Gonsior, M.; Peake, B. M.; Cooper, W. T.; Podgorski, D. C.;D’Andrilli, J.; Dittmar, T.; Cooper, W. J. Characterization of dissolvedorganic matter across the Subtropical Convergence off the SouthIsland, New Zealand. Mar. Chem. 2011, 123 (1−4), 99−110.(4) Koch, B. P.; Dittmar, T.; Witt, M.; Kattner, G. Fundamentals ofmolecular formula assignment to ultrahigh resolution mass data ofnatural organic matter. Anal. Chem. 2007, 79 (4), 1758−63.(5) Sleighter, R. L.; Hatcher, P. G. Molecular characterization ofdissolved organic matter (DOM) along a river to ocean transect of thelower Chesapeake Bay by ultrahigh resolution electrospray ionizationFourier transform ion cyclotron resonance mass spectrometry. Mar.Chem. 2008, 110 (3−4), 140−152.(6) Stenson, A. C.; Marshall, A. G.; Cooper, W. T. Exact masses andchemical formulas of individual Suwannee River fulvic acids fromultrahigh resolution electrospray ionization Fourier transform ioncyclotron resonance mass spectra. Anal. Chem. 2003, 75 (6), 1275−84.(7) Stubbins, A.; Spencer, R. G. M.; Chen, H. M.; Hatcher, P. G.;Mopper, K.; Hernes, P. J.; Mwamba, V. L.; Mangangu, A. M.;Wabakanghanzi, J. N.; Six, J. Illuminated darkness: Molecularsignatures of Congo River dissolved organic matter and itsphotochemical alteration as revealed by ultrahigh precision massspectrometry. Limnol. Oceanogr. 2010, 55 (4), 1467−1477.(8) Zwiener, C.; Frimmel, F. H. LC-MS analysis in the aquaticenvironment and in water treatment–a critical review. Part I:Instrumentation and general aspects of analysis and detection. AnalBioanal. Chem. 2004, 378 (4), 851−61.(9) Richardson, S. D.; Ternes, T. A. Water analysis: Emergingcontaminants and current issues. Anal. Chem. 2005, 77 (12), 3807−38.(10) Reemtsma, T. Determination of molecular formulas of naturalorganic matter molecules by (ultra-) high-resolution mass spectrom-etry: Status and needs. J. Chromatogr., A 2009, 1216 (18), 3687−701.(11) Diaz-Cruz, M. S.; Barcelo, D. LC-MS2 trace analysis ofantimicrobials in water, sediment and soil. TrAC Trends Anal. Chem.2005, 24 (7), 645−657.(12) Haarhoff, J.; Kubare, M.; Mamba, B.; Krause, R.; Nkambule, T.;Matsebula, B.; Menge, J. NOM characterization and removal at sixSouthern African water treatment plants. Drink. Water Eng. Sci. 2010, 3(1), 53−61.(13) Heffner, C.; Silwal, I.; Peckenham, J. M.; Solouki, T. Emergingtechnologies for identification of disinfection byproducts: GC/FT-ICRMS characterization of solvent artifacts. Environ. Sci. Technol. 2007, 41(15), 5419−5425.(14) Zhang, X.; Minear, R. A. Characterization of high molecularweight disinfection byproducts resulting from chlorination of aquatichumic substances. Environ. Sci. Technol. 2002, 36 (19), 4033−8.(15) Zwiener, C.; Richardson, S. D. Analysis of disinfection by-products in drinking water by LC−MS and related MS techniques.TrAC Trends Anal. Chem. 2005, 24 (7), 613−621.(16) Drewes, J. E.; Croue, J.-P. New approaches for structuralcharacterization of organic matter in drinking water and wastewatereffluents. Water Supply 2002, 2 (2), 1−10.(17) Jarusutthirak, C.; Amy, G. Understanding soluble microbialproducts (SMP) as a component of effluent organic matter (EfOM).Water Res. 2007, 41 (12), 2787−2793.(18) Nam, S.-N.; Amy, G. Differentiation of wastewater effluentorganic matter (EfOM) from natural organic matter (NOM) usingmultiple analytical techniques. Water Sci. Technol. 2008, 57 (7), 1009−1015.

(19) Frimmel, F. H.; Abbt-Braun, G. Basic characterization ofreference NOM from central Europe. Similarities and differences.Environ. Int. 1999, 25 (2/3), 191−207.(20) Imai, A.; Fukushima, T.; Matsushige, K.; Kim, Y.-H.; Choi, K.Characterization of dissolved organic matter in effluents fromwastewater treatment plants. Water Res. 2002, 36 (4), 859−870.(21) Pernet-coudrier, B.; Clouzot, L.; Varrault, G.; Tusseau-vuillemin,M.-H.; Verger, A.; Mouchel, J.-M. Dissolved organic matter fromtreated effluent of a major wastewater treatment plant: Character-ization and influence on copper toxicity. Chemosphere 2008, 73 (4),593−599.(22) Shon, H. K.; Vigneswaran, S.; Snyder, S. A. Effluent organicmatter (EfOM) in wastewater: Constituents, effects, and treatment.Crit. Rev. Environ. Sci. Technol. 2006, 36 (4), 327−374.(23) Sirivedhin, T.; Gray, K. A.; Part, I. Identifying anthropogenicmarkers in surface waters influenced by treated effluents: A tool inpotable water reuse. Water Res. 2005, 39 (6), 1154−1164.(24) Barker, D. J.; Stuckey, D. C. A review of soluble microbialproducts (SMP) in wastewater treatment systems. Water Res. 1999, 33(14), 3063−3082.(25) Pehlivanoglu-Mantas, E.; Sedlak, D. L. Wastewater-deriveddissolved organic nitrogen: Analytical methods, characterization, andeffectsA Review. Crit. Rev. Environ. Sci. Technol. 2006, 36 (3), 261−285.(26) Brown, S. C.; Kruppa, G.; Dasseux, J.-L. Metabolomicsapplications of FT-ICR mass spectrometry. Mass Spectrom. Rev.2005, 24 (2), 223−231.(27) Rosso, D.; Lothman, S. E.; Jeung, M. K.; Pitt, P.; Gellner, W. J.;Stone, A. L.; Howard, D. Oxygen transfer and uptake, nutrientremoval, and energy footprint of parallel full-scale IFAS and activatedsludge processes. Water Res. 2011, 45 (18), 5987−5996.(28) Odegaard, H.; Rusten, B.; Westrum, T. A new moving bedbiofilm reactorApplications and results. Water Sci. Technol. 1994, 29(10−11), 157−165.(29) Randall, C. W.; Sen, D. Full-scale evaluation of an integratedfixed-film activated sludge (IFAS) process for enhanced nitrogenremoval. Water Sci. Technol. 1996, 33 (12), 155−162.(30) Khan, M. M. T.; Ista, L. K.; Lopez, G. P.; Schuler, A. J.Experimental and theoretical examination of surface energy andadhesion of nitrifying and heterotrophic bacteria using self-assembledmonolayers. Environ. Sci. Technol. 2011, 45 (3), 1055−1060.(31) Labelle, M.-A.; Juteau, P.; Jolicoeur, M.; Villemur, R.; Parent, S.;Comeau, Y. Seawater denitrification in a closed mesocosm by asubmerged moving bed biofilm reactor. Water Res. 2005, 39 (14),3409−3417.(32) Hertkorn, N.; Frommberger, M.; Witt, M.; Koch, B. P.; Schmitt-Kopplin, P.; Perdue, E. M. Natural organic matter and the eventhorizon of mass spectrometry. Anal. Chem. 2008, 80 (23), 8908−19.(33) Kim, S.; Kramer, R. W.; Hatcher, P. G. Graphical method foranalysis of ultrahigh-resolution broadband mass spectra of naturalorganic matter, the Van Krevelen diagram. Anal. Chem. 2003, 75 (20),5336−5344.(34) Shakeri Yekta, S.; Gonsior, M.; Schmitt-Kopplin, P.; Svensson,B. H. Characterization of dissolved organic matter in full scalecontinuous stirred tank biogas reactors using ultrahigh resolution massspectrometry: A qualitative overview. Environ. Sci. Technol. 2012, 46(22), 12711−12719.(35) Kendrick, E. A mass scale based on CH2 = 14.0000 for highresolution mass spectrometry of organic compounds. Anal. Chem.1963, 35 (13), 2146−2154.(36) Dignac, M. F.; Ginestet, P.; Rybacki, D.; Bruchet, A.; Urbain, V.;Scribe, P. Fate of wastewater organic pollution during activated sludgetreatment: Nature of residual organic matter.Water Res. 2000, 34 (17),4185−4194.(37) Henze, M.; Comeau, Y., Wastewater characterization. InBiological Wastewater Treatment: Principles, Modeling, And Design,Henze, M., van Loosdrecht, M. C. M., Ekama, G. A., Brdjanovic, D.,Eds.; IWA Publishing: London, 2008; pp 33−52.



(38) Siedlecka, E. M.; Kumirska, J.; Ossowski, T.; Glamowski, P.;Golebiowski, M.; Gajdus, J.; Kaczynski, Z.; Stepnowski, P.Determination of volatile fatty acids in environmental aqueoussamples. Pol. J. Environ. Stud. 2008, 17 (3), 351−356.(39) Koch, B. P.; Ludwichowski, K.-U.; Kattner, G.; Dittmar, T.;Witt, M. Advanced characterization of marine dissolved organic matterby combining reversed-phase liquid chromatography and FT-ICR-MS.Mar. Chem. 2008, 111 (3−4), 233−241.(40) Leu, S.-Y.; Chan, L.; Stenstrom, M. K. Toward long solidsretention time of activated sludge processes: Benefits in energy saving,effluent quality, and stability. Water Environ. Res. 2012, 84 (1), 42−53.(41) Soliman, M. A.; Pedersen, J. A.; Park, H.; Castaneda-Jimenez, A.;Stenstrom, M. K.; Suffet, I. H. Human pharamaceuticals, antioxidants,and plasticizers in wastewater treatment plant and water reclamationplant effluents. Water Environ. Res. 2006, 79 (2), 156−167.(42) Jiao, N.; Herndl, G. J.; Hansell, D. A.; Benner, R.; Kattner, G.;Wilhelm, S. W.; Kirchman, D. L.; Weinbauer, M. G.; Luo, T.; Chen, F.;Azam, F. Microbial production of recalcitrant dissolved organic matter:Long-term carbon storage in the global ocean. Nat. Rev. Microbiol.2010, 8 (8), 593−599.(43) Gruber, D. F.; Simjouw, J. P.; Seitzinger, S. P.; Taghon, G. L.Dynamics and characterization of refractory dissolved organic matterproduced by a pure bacterial culture in an experimental predator-preysystem. Appl. Environ. Microbiol. 2006, 72 (6), 4184−4191.



molecular characteristics and differences of effluent organic matter from parallel activated sludge...

Documents