hydrogen peroxide in soil & groundwater remediation site... · 2020-04-04 · treatment methods...

Hydrogen Peroxide

Soil & Groundwater Remediation

in

Site remediation using hydrogen peroxideIntroduction. Hydrogen peroxide is often the oxidant of choice for soil and groundwaterremediation, as it is a safe and effective remediation tool. Techniques utilizing hydrogen peroxideshow significant benefits, including reduced cleanup time and relative ease of application at theremediation site.

This brochure presents various technologies available for treating contaminated soil andgroundwater, including traditional and innovative treatments. Additional information includedcovers technologies using hydrogen peroxide, specifically direct peroxidation of soils,landfarming, bioreactors and in-situ bioremediation. Information on alternative oxygen sources forin-situ bioremediation and peroxide stability is also included. Case studies highlight differentcontaminants and site hydrogeological characteristics.

Hydrogen peroxide from Solvay Interox offersa treatment alternative

Treatment methodsA number of different treatment technologies apply for use on contaminated soil and groundwater.Table One lists the pros and cons of each.

Among the various cleanup methods, peroxygens perform well in several technologies, includingperoxidation and bioremediation.

Uses of hydrogen peroxide in soil remediationPump and treat. Pump and treat technology involves the removal of groundwater from the aquiferand treatment of the various pollutants. Treatment can consist of a variety of technologies,including bioreactors, filtration, and oxidation systems. The clean groundwater is then reinjectedinto the aquifer. This process allows for the mass transfer of the pollutant from the soil to thegroundwater and treatment to nondetectable levels in the soil. Unfortunately, the clean-up rate islimited by the solubility of the pollutant in the groundwater and cleanups can take decades.Hydrogen peroxide is used in a number of pump and treat systems, including iron removalsystems and Advanced Oxidation Processes (AOPs), such as UV/ H 2O2, and 03 /H2O2 as well asbioreactor systems.

Peroxidation. Peroxidation technology is the direct oxidation of organic contaminants in the soil.This treatment occurs either in-situ or ex-situ, with peroxide alone or catalyzed with Fenton’sReagent. To be effective, the soil pollutants must be amenable to oxidation. Peroxidation allowsfor much shorter treatment times than traditional pump and treat or bioremediation.

In-situ peroxidation partially oxidizes the contaminants to improve the biodegradability of thecompounds in the unsaturated zone. Once this is accomplished, in-situ bioremediation occurs at agreatly enhanced rate and reduced cost.

www.solvayinterox.com.auCopyright 2001, Solvay Interox, All rights reserved.Revised 04-09-01, Soil & Groundwater Remediation, of 13

Biological treatment. Biological treatment can take a number of different forms, includinglandfarming, pump and treat bioreactor systems and in-situ bioremediation. In order forbioremediation to be effective, the contaminant must be biodegradable and the levels ofcontaminants must not be high enough to be toxic to the microorganisms. If toxicity exists,peroxidation may be used to reduce toxicity prior to biological treatment.

Landfarming. Landfarming consists of plowing the appropriate microorganisms, nutrients andsometimes additional wastes into the soil to form a compost. This mixture provides theappropriate environment for the microorganisms to degrade the contaminants. A number offactors impact the success of this type of treatment, including: type and extent of contamination,moisture level and pH of the soil, and nitrogen and phosphate content. Weekly tilling or disking isoften necessary to introduce oxygen into the system. Operators estimate cost for this type oftreatment at $20-30/ton.1

Recent studies indicate that the use of peroxygen compounds, such as Ixper® calcium peroxide,can replace the normal tilling used for aeration of the soil. Solvay lnterox can provide additionalinformation on this product.

Bioreactor systems. Bioreactor systems, used in pump and treat systems, represent an efficientand inexpensive approach for treating halogenated aliphatics. Limitations in oxygen transfer canslow the rate of degradation, as well as increase capital investment significantly. Hydrogenperoxide improves bioreactor efficiency when dealing with limited oxygen solubility.

In-situ bioremediation. In nature, biodegradation occurs slowly because of the low population ofmicroorganisms with degradation ability. Degradation is also hindered because of environmentalconditions, such as nutrient levels. For bioremediation to be commercially viable, site managersmust stimulate the natural biodegradation of hazardous compounds to achieve practicalremediation rates. By assisting nature, the cleanup time can be drastically shortened.

In-situ bioremediation offers the advantage of being used where other technologies will not work,such as at sites that cannot be excavated. In-situ treatment avoids the cost of excavation as wellas freight for off-site treatment. An added advantage is that you can treat the soil andgroundwater in a one-step process with minimal equipment. Additionally, the treatment can easilyfollow the contamination plume in the groundwater. All of these factors make in-situbioremediation more cost-effective.

For in-situ bioremediation to be effective, the components must also biodegrade readily. Asdiscussed previously, peroxidation may be useful in reducing toxicity of various contaminantsprior to biodegradation.


Method Advantages Disadvantages

Vitrification Non-leachable product High levels of clay necessaryHigh electrical costsLow number of completed cleanups

Fixation Low cost Contaminant is not destroyedReadily available raw material Long term effects not known

Air Sparging/Soil Demolition and excavation Capital investment is highVapor Extraction not needed Must have a volatile contaminant

Steam Stripping Allows for removal of less Possible contaminant leachingvolatile compounds problems

High utility costs

Incineration Able to treat a wide Soil excavation is necessaryrange of contaminants Soil must have a high BTU content

Lengthy permitting requirementsNegative public imageHigh capital cost

Pump and Treat Able to treat a wide Long cleanup timerange of contaminants

Peroxidation Reduced cleanup times Contaminants must be susceptible toLow capital investment to oxidation

Bioremediation Can be done either Long cleanup timein-situ or ex-situAble to treat a wide

range of contaminants

Microbial metabolic reactions cause slownatural biodegradation

Application methodsA typical bioremediation system includes ground water recovery and treatment, and the additionof nutrients, oxygen and acclimated microbes. Some sites discharge treated water offsite andsupply fresh makeup water to the subsurface, in lieu of reinjecting treated water as makeup.2

Groundwater treatment may consist of bioreactors, carbon adsorption and UV/H 2O2.Figure One illustrates a typical process diagram for in-situ bioremediation.

Table One:Treatment methods for contaminated soiland groundwater


Optimum conditions and requirements

Bioremediation relies on the ability of living organisms to utilize organic chemicals as sources offood and energy. Bacteria assimilate nutrient molecules, which are required for the maintenance ofgrowth and metabolism of all organisms. Then enzymes act upon the nutrients. Althoughmicroorganisms normally utilize the same molecular food sources as humans (principally sugarsand amino acids) almost any organic compound — even a toxic pollutant — theoretically can beused by microbes as a source of food or energy, if the bacteria can absorb the compound.

Sequential pathways composed of one or more enzymatic reactions have evolved in all livingorganisms to allow cells to metabolize nutrients and convert them either into chemical buildingblocks for new cell growth or into energy. Since each living cell makes use of hundreds ofdifferent metabolic pathways to fulfill its myriad chemical needs, cells can metabolize a very broadrange of carbon-based compounds. These metabolic reactions cause the slow, naturalbiodegradation of many chemicals in the environment. For difficult-to-degrade compounds,biodegradation may require co-metabolites.

Along with a suitable food source and the presence of micronutrients, the site must also containcontaminant degrading microbes for bioremediation to occur. If indigenous microorganisms donot exist, then the addition of commercial microbes may be necessary. Additionally, soil pH andtemperature can also impact bioremediation. Soils with a neutral pH and temperatures between8°C and 30°C have proven most suitable.

Table Two gives a simple screening mechanism for whether or not in-situ bioremediation is agood candidate. A treatability/feasibility study should still be done to confirm whether or notin-situ bioremediation could succeed.

If conditions of the soil and water at the site do not provide optimum support for microbialgrowth, addition of nutrients, the addition of oxygen and microbes can improve the efficiency ofthe reaction. Normally added nutrients include ammonium phosphate, sodium chloride,magnesium sulfate and potassium phosphate.

Figure One: In-situ bioremediation

NutrientsOxygensource

Recovery

Soilmatrix

Aquifer


Table Two: Test for determining thefeasibility of in-situ bioremediationParameter Score

Contaminant characteristicsStructure:

Simple hydrocarbon C1 to C15 0Hydrocarbon C12-C20 -1Hydrocarbon greater than C20 -2Alcohols, phenols, amines 0Acids, esters, amides 0Ethers, mono-chlorinated hydrocarbons -1Multi-chlorinated hydrocarbons -2Pesticides -2

Sources:Well-defined point sources +1Undefined multiple sources -1

HydrogeologyAquifer permeability (cm/sec):

Greater than 10-3 010-3 to10-4 -110-4 to 10-5 -2

Aquifer thickness (feet):20 +110 05 -1Less than 2 -2

Homogeneity:Uniform, well-defined geology +1Heterogeneous, poorly defined geology -1

Depth to aquifer (feet):20 +110 05 -1Less than 2 -2

Soil and groundwater chemistryGroundwater pH:

Greater than 10 -28-10 -16.5-8 04.5-6.5 -1Less than 4.5 -2

Groundwater chemistry:High Fe, S, Ca, Mg, Cu, Ni -0.5High NH4 + and Cl– -0.5Heavy metals (As, Cd, Hg) -0.5

Interpreting the total score0 or greater Site appears to be suitable for bioreclamation-1 to -2 Possible areas of concern-2 to -4 Areas of significant concernLess than -4 Success is unlikelySource: Adapted from Remediation Technologies, Inc.3


Alternative oxygen sourcesOne of the main reasons for decreased efficiency of bioremediation systems concerns lack ofoxygen in the contaminated soil and aquifer. For this reason, oxygen is introduced into a system,so as not to be the limiting factor in biodegradation. Oxygen can be added through physical orchemical methods.

Physical addition consists of air sparging, oxygen sparging, air venting and pumping oxygen-enriched water into the contaminated aquifer. Problems exist with these forced air systems ifbiofouling of the sparging surface accurs, which is caused by the active biological populationpresent at the interface of the biological and mechanical systems occurs.4 This biofouling oftencauses problems with the phase transfer of oxygen into the aquifer. When using air for sparging,the highest concentration achievable within the aquifer is 8-10 mg/L. By using pure oxygen, theachievable oxygen concentration approaches 40 mg/L.

Chemical addition consists of peroxide or nitrate (N O - 3- ) addition. Nitrate usage is problematic

because concentration is typically limited to 10 ppm in the groundwater due to its potentialenvironmental impact. Nitrate addition only works in low oxygen or oxygen deprived systems.

In determining oxygen requirements, both the biological oxygen demand and the non-biologicaloxygen demand must be considered. Non-biological demand results from the oxygenrequirements of reduced, multivalent elements, such as iron, sulfur and manganese that may bepresent in the aquifer.5

Hydrogen peroxide advantagesHydrogen peroxide is a clear liquid, slightly denser than water. Infinitely soluble in water, itefficiently delivers oxygen to groundwater. For example, 200 mg/L of 50% peroxide delivers47 mg/L of oxygen.

Bioremediation is normally started at low concentrations of peroxide (40-50 mg/L as 100% H202)or with pure oxygen. Once the bacterial population is established and acclimated to the hydrogenperoxide or oxygen, the concentration can be increased. Increments of approximately 50 to 250mg/L in increasing time intervals from approximately one week to one month achieve anincreased presence of oxygen. Such gradual increases of peroxide concentrations can continue upto a peroxide concentration of about 1000 mg/L.6

Unlike mechanical means of aeration, biofouling has not been shown to be a problem withperoxide dosing systems. Therefore, the use of hydrogen peroxide can eliminate a majormaintenance cost that exists with mechanical systems.7


Hydrogen peroxide-assisted bioremediationallows a shorter estimated cleanup time

Hydrogen peroxide stabilityStability of the hydrogen peroxide solution injected into the groundwater is extremely important. Ifperoxide decomposes too quickly into oxygen and water, the oxygen may not get far enoughdowngradient to serve as an oxygen source for the microorganisms. Also with poor stability, theamount of hydrogen peroxide necessary for a remediation project can increase dramatically, thusincreasing the project cost. For this reason, the stability of hydrogen peroxide must be consideredfor each and every system. Many methods exist for determining this stability, including columntests which determine the half-life of a dilute (500 mg/kg) peroxide solution in soil.

Peroxide decomposition can result from either homogeneous or heterogeneous catalysis. Iron andcopper are the most common catalysts, but other metal species can also serve to decrease thestability of the peroxide. In addition to metal catalysis, enzymatic catalysts, such as catalase, alsonegatively affect peroxide stability.

If peroxide stability is a problem, stabilizers can be added most easily by amending the nutrientformulation. For example, adding stannate or phosphate to hydrogen peroxide solutions decreasesthe catalytic action of iron.8 Practical experience shows that excessive use of phosphate as astabilizer, however, leads to aquifer plugging due to precipitation of the phosphates. This pluggingproblem can be avoided by using polyphosphates because of their higher solubilities. Sodiumpyrophosphate reportedly stabilizes H 202 by either precipitating or sequestering the ionic Fespecies and acts as an effective stabilizer in the presence of up to 10 mg/L Fe.9

To reduce decomposition from enzymatic catalysts, several options have been reported; however,the only stabilizer reportedly used under field conditions is citrate.10

The addition of small amounts of sodium silicate increases peroxide stability. In addition, silicatecan also improve soil permeability.

Other peroxygen compounds, such as calcium peroxide and magnesium peroxide, demonstrategood stability during in-situ bioremediation.

Case studiesMontana, USAThis creosote and pentachlorophenol contaminated site was the first site to have a Record of Decision (ROD) stipulating in-situ bioremediation for the contaminated upper aquifer.

A preliminary feasibility study determined that dissolved oxygen (DO) was a primary limitingfactor for biodegradation within the aquifer. Application of elevated levels of DO through the useof 100 mg/L H 202 produced a high oxygen zone within the contaminant plume.11 Monitoring of thesite nutrient and DO levels indicated sustained natural biological activity.

Full scale cleanup of the site began in 1989 and will probably continue until after 2000. Althoughoperators estimated bioremediation to cost more than a traditional pump and treat system, theyrealized savings from the shorter cleanup time, estimated at 50%.12


Fuel Pipeline – Midwestern U.S.A 135,000 litre underground gasoline spill contaminated a 135 x 270 metre area of impermeablesoil on top of a fractured lime stone bedrock. A collection system recovered 4,500 litres ofpetrol.

The owner chose H202-assisted bioremediation because it allowed a shorter estimated cleanup time:18-60 months as opposed to a non-assisted time estimate of 20 years. They found that the existingmicrobial population in the groundwater could easily degrade the petrol. However, it would benecessary to expand the population by raising the oxygen level in the groundwater through H202addition. Hydrogen peroxide addition began at 1,000 mg/L, based on a groundwater flow of 50 gpm.Lab work indicated an optimum feed rate of 300 mg/L, yet 700 mg/L proved most effective duringthe first 6 months of the full scale cleanup, due to the oxygen-depleted site conditions. After theinitial treatment period, the peroxide dose level was reduced to the 300 mg/L level.

Petrol Station – Southeastern United StatesA spill of 4000 litres of leaded petrol contaminated a petrol station site. The soil was mainlya silty, sandy clay. They recovered a total of 675 litres of petrol via phase separation of theextracted water and from the excavated soil. The balance, 3400 litres, remained bound in the soilas the adsorbed phase, and dissolved in the groundwater. They augmented the recoveredgroundwater with nutrients and hydrogen peroxide after treatment through an air stripper. Thenthey reintroduced the groundwater to the contaminated subsurface through an infiltration gallery.Eighteen months of operation biodegraded over 3000 litres of hydrocarbon.14

Petrol Station – Velsen, NetherlandsWork sponsored by Solvay Interox, in conjunction with DHV, a Dutch engineering and servicesfirm, successfully remediated a contaminated petrol station site with hydrogen peroxide.13

Contamination at the site existed in both the vadose and saturated zones.

Along with the actual cleanup of the site, an additional objective was to determine whether or notcatalase activity occurred in the hydrogen peroxide piping system. No measurable peroxidedecomposition could be attributed to either the enzymatic activity of the catalase or the biofilm onthe surface of the piping.

In-situ bioremediation succeeded for several reasons: it met the cleanup objectives, no buildingswere demolished, and the total cleanup cost reached only 85% of traditional treatment methods.

Petrol Station – Asten, NetherlandsA petrol filling station in the Netherlands became contaminated with 36,000 litres of petroland a small amount of diesel fuel. The site was mainly sand, allowing good permeability. Phaseseparation recovered a total of 24,000 litres of free product. The remainder of the cleanup usedin-situ bioremediation with hydrogen peroxide. Total cleanup costs for the bioremediation portionapproximated $125/ton, including the testing and monitoring program.

Fuel Oil Spill – GermanyApproximately 112,500 litres of fuel oil polluted the vadose zone of a sandy soil in Germany. Anine month cleanup program reduced the concentration of hydrocarbons from an excess of 1000mg/kg to less than 20 mg/kg. Hydrogen peroxide was added at 100 mg/L to the infiltration watersource. Total cleanup costs approximated $45/yd3, with peroxide and nutrient addition accountingfor 25% of the cost.15


References

1. Golden, Randy and Hopkins, Jeffrey, “Fine Tune Landfarming”, Soils, October, 1992, p.36.2. Hicks, Brian and Caplan, Jason, “Bioremediation: A Natural Solution”, Pollution Eng.,

January 15, 1993, p.30.3. Brubaker, Gaylen, “Screening Criteria for In-Situ Bioreclamation of Contaminated Aquifers”,

RETEC, 1989.4. Wilson, S.B. and Brown, R.A., “In-Situ Bioremediation: A Cost Effective Technology

to Remediate Subsurface Organic Contamination”, GWMR, Winter 1989, p.173.5. Aggarwal, P. K. et al.; “Methods to Select Chemicals for in-Situ Biodegration of Fuel

Hydrocarbons”, Air Force Engineering and Services Center, July 1990.6. Staps, J.J.M., “International Evaluation of In-Situ Biorestoration of Contaminated

Soil & Groundwater”, National Institute of Public Health and Environmental Protection,January 1990.

7. Brown, Richard A., “Oxygen Sources for Biotechnological Applications”, Superfund 89,Hazardous Materials Control Research Institute, pp. 231-234.

8. Schumb, W.C., Satterfield, C.N., and Wentworth, R.L., Hydrogen Peroxide, AmericanChemical Society Monograph Series 128.

9. Ibid.10. Alyea, H.N. and Pace, J., “Inhibitors in the Decomposition of Hydrogen Peroxide by

Catalase”, Journal American Chemical Society, Vol. 55, December 1933, pp. 4801-4806.11. Piotrowski, MR. and Carraway, J.W.; “Full-Scale Bioremediation of Soil and Groundwater

at a Superfund Site: A Progress Report”, HazMat South ‘91, Tower ConferenceManagement Company.

12. Piotrowski, MR., “In-Situ Design For Aquifer Cleanup”, Environmental Protection, p. 36,May 1992.

13. DHV report to Interox on the Velsen site.14. Wilson and Brown.15. Staps, 1990.


Solvay Interox is dedicated to customer satisfaction

We strive to make your experience with Solvay lnterox safe, efficient, and cost effective.Most of the important product and contact information is readily available atwww.solvayinterox.com.au. You may also contact us by phoning 61 2 9316 8000, faxing61 2 93166445 or writing to Solvay Interox, Pty.Ltd. at 20-22 McPherson Street,Banksmeadow, NSW 2019.

Solvay Interox Quality Policy

"Total Customer Satisfaction through Operational Excellence"This policy means that we pursue the highest standards of excellence in every facet of ourbusiness. We dedicate ourselves to this effort because we know that our success dependson satisfying you.

Our Quality Management System demonstrates this commitment by meeting therequirements of the ISO 9002:1994 International Quality Standard. The manufacture anddistribution of hydrogen peroxide at our plant in Banksmeadow, NSW, as well as thesupport activities at the Banksmeadow headquarters, are all registered to ISO 9002:1994.

Safety

Like all other powerful chemicals, hydrogen peroxide must be treated with respect andhandled appropriately. For a full discussion of safe handling of this product, please seeour publication "Hydrogen Peroxide Safety and Handling," available upon request, or asa download from our website at www.solvayinterox.com.au . Solvay Interox alsoconducts safety training sessions as part of it’s PARTNERS program.

Delivery

Solvay Interox distributes product from the Banksmeadow site and a number ofstrategically located distribution warehouses. Hydrogen peroxide is packed in 25 kgcarboys or 250 kg Mauser drums. Bulk hydrogen peroxide is shipped in 1,200 kgIntermediate Bulk Containers (IBCs), 2,500 kg Road Tanks and 20 or 24 tonne Isotanks.

Responsible Care

Recognising the importance of preserving the environment of the planet we share, and thehealth and safety of the employees who produce our products, Solvay Interox activelysupports the Responsible Care program of PACIA.


PARTNERS PROGRAM

PARTRNERS is a collaborative program of development between Solvay and it'scustomers. It aims to establish the appropriate levels of cooperation and services to beexchanged as part of the product provided by Solvay lnterox. Issues such as SafetyTraining, Audits, Engineering and Technical Support can be covered by the PARTNERSprogram.

PARTNERS aims to more effectively focus resources from Solvay Interox on those issuesof significance to our customers. This is achieved by an ongoing dialogue to developprograms and projects, which improves in total the on-site performance of peroxygensand the operations of both organisations.

The nucleus of PARTNERS commences with safety and safety related topics such asoperator training and safety audits. Other areas of potential development includeengineering, design, HAZOP, production performance auditing and technical processinvestigations. The level of partnership development will evolve through time to includethose areas of importance to both partners.

Structured PARTNERS IN SAFETY training for your customers, staff , contract drivers etc.

• 24 hour emergency response hotline 1800 023 488.

• Safety audits of storage facilities.

• Technical service and advice.

• Staff training on efficient use of peroxygens and operational audits of processes.

• Access to our research and development findings.

• Participation in HAZOP studies.

• Engineering support for bulk installations and dosing systems.


Disclaimer: "This Product Leaflet summarises our best knowledge of the health and sfety hazard information of the product and how to safely handleand use the product in the workplace. Each user should read this Product Leaflet and consider the information in the context of how the product will be handled and used in the workplace including in conjunction with other products.If clarification or further information is needed to ensure that an appropriate risk assessment can be made the user should contactthis company.

Solvay Interox, Pty.Ltd.20-22 McPherson StreetBanksmeadow, NSW 2019Tel: 61 2 93168000Fax: 61 2 93166445www.solvayinterox.com.au

www.solvayinterox.com.auCopyright 2001, Solvay Interox, All rights reserved.Revised 04-09-01, Soil & Groundwater remediation, of 13

Our responsibility for products sold is subject to our standard terms and conditions, a copy of which is sent to our customers andis available on request."

hydrogen peroxide in soil & groundwater remediation site... · 2020-04-04 · treatment methods...

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