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| − | Bioremediation is the process by which contaminants in soil and/or groundwater are treated biologically, primarily by microorganisms or biomolecules generated by the cells. Bioremediation processes can take place under oxic (with oxygen) or anoxic (without oxygen) conditions. This article focuses on enhanced in situ bioremediation (EISB) for the anaerobic biodegradation of organic contaminants, particularly '''chlorinated solvents''', in soil and groundwater. However, much of the information provided is applicable to other contaminant types. EISB is frequently selected as a remedial technology as it can provide complete degradation of contaminants utilizing natural microbial processes, is able to implement in a variety of site conditions, and is relatively low cost compared to more active engineered remedial systems.
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| | <div style="float:right;margin:0 0 2em 2em;">__TOC__</div> | | <div style="float:right;margin:0 0 2em 2em;">__TOC__</div> |
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| | '''Related Articles:''' | | '''Related Articles:''' |
| − | *[[In Situ Anaerobic Bioremediation Design Considerations]]
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| | '''Key Resource(s)''': | | '''Key Resource(s)''': |
| − | *[http://www.environmentalrestoration.wiki/images/4/44/USEPA-2013-introductiontoinsitubioremediationofgroundwater.pdf Introduction to In Situ Bioremediation of Groundwater. EPA 542-R-13-018]<ref name= "USEPA2013Intro">USEPA, 2013. Introduction to In Situ Bioremediation of Groundwater. EPA 542-R-13-018. [http://www.environmentalrestoration.wiki/images/4/44/USEPA-2013-introductiontoinsitubioremediationofgroundwater.pdf Report pdf]</ref>
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| − | *[http://www.navfac.navy.mil/content/dam/navfac/Specialty%20Centers/Engineering%20and%20Expeditionary%20Warfare%20Center/Environmental/Restoration/er_pdfs/d/navfacexwc-ev-tm-1501-erd-design-201503f.pdf Design considerations for Enhanced Reductive Dechlorination. TM-NAVFAC-EXWC-EV-1501]<ref name= "NAVFAC2015D">NAVFAC, 2015. Design considerations for Enhanced Reductive Dechlorination. TM-NAVFAC-EXWC-EV-1501. [http://www.navfac.navy.mil/content/dam/navfac/Specialty%20Centers/Engineering%20and%20Expeditionary%20Warfare%20Center/Environmental/Restoration/er_pdfs/d/navfacexwc-ev-tm-1501-erd-design-201503f.pdf Report pdf]</ref>
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| | ==Introduction== | | ==Introduction== |
| − | Laboratory and field applications over the past two decades have shown that microorganisms in subsurface environments can degrade a wide variety of chemicals to environmentally acceptable end products. Anaerobic bioremediation of contaminated groundwater and geologic materials typically involves in-situ treatment via '''biostimulation''' using various carbon-based '''amendments''', because most sites lack sufficient organic carbon to promote anaerobic microbial respiration. In some cases, '''bioaugmentation''', the injection of a microbial culture, may be required to provide the appropriate microbial community to promote complete degradation of the target contaminants. Anaerobic bioremediation remedies typically involve an initial amendment application, followed by a period of monitoring to demonstrate the remedial goals have been achieved and evaluate the need for additional amendment applications.
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| − | ==Degradation Processes==
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| − | Under anaerobic conditions, organic contaminants can serve as the electron acceptors or electron donors during biodegradation processes<ref name= "USEPA2013Intro"/>; we refer to the former as “anaerobic reductive bioremediation” and the latter as “anaerobic oxidative bioremediation”.
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| − | *Anaerobic reductive bioremediation relies on the presence of biologically available organic carbon, which may be naturally present or added to stimulate biological activity. Organic bioremediation amendments, referred to as organic substrates or electron donors, generate and sustain anoxic conditions by consuming oxygen via aerobic respiration, as well as other electron acceptors, during its biodegradation. For example, chlorinated solvents such as trichloroethene (TCE) serve as electron acceptors and undergo '''reductive dechlorination''' under anaerobic conditions in the presence of an electron donor. This microbial-mediated process can result in the complete degradation of many specific chlorinated solvents to innocuous end products.
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| − | *Anaerobic oxidative bioremediation relies on other electron acceptors such as nitrate or sulfate for direct microbial metabolic oxidation of a contaminant serving as the electron donor. This approach may be applied for the treatment of non-chlorinated hydrocarbon compounds where oxygen has already been depleted.
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| − | In contrast, cometabolism occurs when microorganisms do not utilize the organic contaminant as an energy source, but the contaminant is fortuitously degraded by enzymes or co-factors produced during the metabolism of another compound.
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| − | ==Contaminant Treatability==
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| − | Many contaminants can be degraded by bioremediation in both laboratory and field settings including the use of biological treatment processes for common organic contaminants as well as '''metals, metalloids''' and perchlorate (Tables 1, 2).
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| − | {| class="wikitable"
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| − | ! Contaminant!! Aerobic Oxidation!! Aerobic Cometabolism!! Anaerobic Oxidation !! Anaerobic Reduction!! Cometabolic Anaerobic Reduction
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| − | | Perchlorate<ref name= "USEPA2013Intro"/><ref>Stroo, H.F. and Ward, C.H. eds., 2008. In situ bioremediation of perchlorate in groundwater. Springer Science & Business Media. [https://doi.org/10.1007/978-0-387-84921-8_1 doi: 10.1007/978-0-387-84921-8_10]</ref>||[[File:Circle with diagnal line.PNG|15px]]||[[File:Circle with diagnal line.PNG|15px]]||[[File:Circle with diagnal line.PNG|15px]]
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| − | | TNT/RDX/HMX<ref>Spain, J.C., Hughes, J.B. and Knackmuss, H.J. eds., 2000. Biodegradation of nitroaromatic compounds and explosives. CRC Press</ref><ref name= "Kalderis2011">Kalderis, D., Juhasz, A.L., Boopathy, R. and Comfort, S., 2011. Soils contaminated with explosives: Environmental fate and evaluation of state-of-the-art remediation processes (IUPAC Technical Report). Pure and Applied Chemistry, 83(7), pp.1407-1484. [https://doi.org/10.1351/pac-rep-10-01-05 doi:10.1351/pac-rep-10-01-05]</ref><ref>Battelle, 2015. Attenuation Pathways for Munitions Constituents in Soils and Groundwater, NAVFAC Technical Report - TR-NAVFAC-EXWC-EV-1503 [http://www.environmentalrestoration.wiki/images/5/55/NAVFAC-2015-AttenuationPathways.pdf Report pdf]</ref> || [[File:Circle black fill.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]] || [[File:Circle black fill.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]] || [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]
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| − | | 1,4-dioxane<ref>Mahendra, S. and Alvarez-Cohen, L., 2006. Kinetics of 1, 4-dioxane biodegradation by monooxygenase-expressing bacteria. Environmental Science & Technology, 40(17), pp.5435-5442. [https://doi.org/10.1021/es060714v doi:10.1021/es060714v]</ref><ref>Steffan, R.J., McClay, K.R., Masuda, H. and Zylstra, G.J., 2007. ER-1422: Biodegradation of 1, 4-Dioxane No. CU-1422. Shaw Environmental Inc Lawrenceville NJ. [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-1422/ER-1422/(language)/eng-US ER-1422]</ref><ref>Adamson, D.T., Anderson, R.H., Mahendra, S. and Newell, C.J., 2015. Evidence of 1, 4-dioxane attenuation at groundwater sites contaminated with chlorinated solvents and 1, 4-dioxane. Environmental Science & Sechnology, 49(11), pp.6510-6518. [https://doi.org/10.1021/acs.est.5b00964 doi:10.1021/acs.est.5b00964]</ref>||[[File:Circle Open.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]||[[ File:Circle with diagnal line.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]
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| − | | Chloroethenes<ref>Spain, J.C. ed., 1995. Biodegradation of nitroaromatic compounds. Environmental Science Research Vol. 49 [https://doi.org/10.1007/978-1-4757-9447-2 doi 10.1007/978-1-4757-9447-2]</ref><ref name= "Wiedemeir1999">Wiedemeier, T.H., Newell, C.J., Rifai, H.S., and Wilson, J.T., 1999. Natural attenuation of fuels and chlorinated solvents in the subsurface. John Wiley & Sons. [https://doi.org/10.1002/9780470172964 doi:1 0.1002/9780470172964]</ref>|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]] || [[File:Circle black fill.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]
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| − | | Chloroethanes<ref name= "Wiedemeir1999"/><ref name="Lawrence2006">Lawrence, S.J., 2006. Description, Properties, and Degradation of Selected Volatile Organic Compounds Detected in Ground Water--A Review of Selected Literature No. 2006-1338. [http://www.environmentalrestoration.wiki/images/5/5f/Lawrence-2006-Description_properties_degradation_of_VOCs.pdf Report pdf]</ref>|| [[File:Circle black fill.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]]
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| − | | Chloromethanes<ref name= "Wiedemeir1999"/><ref name="Lawrence2006"/>|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]] || [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]
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| − | | Chlorobenzenes<ref name= "Wiedemeir1999"/><ref name="Lawrence2006"/><ref name= "Field2008">Field, J.A. and Sierra-Alvarez, R., 2008. Microbial degradation of chlorinated benzenes. Biodegradation, 19(4), pp.463-480. [https://doi.org/10.1007/s10532-007-9155-1 doi:10.1007/s10532-007-9155-1]</ref><ref>Adrian, L. and Görisch, H., 2002. Microbial transformation of chlorinated benzenes under anaerobic conditions. Research in Microbiology, 153(3), pp.131-137. [https://doi.org/10.1016/s0923-2508(02)01298-6 doi:10.1016/s0923-2508(02)01298-6]</ref>|| [[File:Circle black fill.PNG|15px]] || [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle Open.PNG|15px]]
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| − | | Nitrobenzenes<ref name= "Kalderis2011"/><ref name= "Wiedemeir1999"/>|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle Open.PNG|15px]][[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]
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| − | | BTEX<ref name="Lawrence2006"/><ref name= "Field2008"/><ref>Prenafeta-Boldú, F.X., Vervoort, J., Grotenhuis, J.T.C. and Van Groenestijn, J.W., 2002. Substrate interactions during the biodegradation of benzene, toluene, ethylbenzene, and xylene (BTEX) hydrocarbons by the fungus Cladophialophora sp. strain T1. Applied and Environmental Microbiology, 68(6), pp.2660-2665. [https://doi.org/10.1128/aem.68.6.2660-2665.2002 doi: 10.1128/aem.68.6.2660-2665.2002]</ref>|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle Open.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]] || [[File:Circle black fill.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle with diagnal line.PNG|15px]]
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| − | | MTBE and TBA<ref>Zeeb, P. and Wiedemeier, T.H., 2007. Technical protocol for evaluating the natural attenuation of MTBE. API Publication 4761. [http://www.environmentalrestoration.wiki/images/9/9f/API_MNA_MTBE_protocol.pdf Report pdf]</ref><ref>USEPA, 2007. Monitored Natural Attenuation of Tertiary Butyl Alcohol (TBA) in Ground Water at Gasoline Spill Sites. EPA 600-R-07-100. [http://www.environmentalrestoration.wiki/images/c/c1/epa_600-r-07-100.pdf Report pdf]</ref>|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]|| [[File:Circle Open.PNG|15px]]
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| − | | Chloropropanes<ref>Maness, A.D., Bowman, K.S., Yan, J., Rainey, F.A. and Moe, W.M., 2012. Dehalogenimonas spp. can reductively dehalogenate high concentrations of 1, 2-dichloroethane, 1, 2-dichloropropane, and 1, 1, 2-trichloroethane. AMB Express, 2(1), p.54. [https://doi.org/10.1186/2191-0855-2-54 doi:10.1186/2191-0855-2-54]</ref><ref>Schlötelburg, C., Von Wintzingerode, F., Hauck, R., Hegemann, W. and Göbel, U.B., 2000. Bacteria of an anaerobic 1, 2-dichloropropane-dechlorinating mixed culture are phylogenetically related to those of other anaerobic dechlorinating consortia. International journal of systematic and evolutionary microbiology, 50(4), pp.1505-1511.[ https://doi.org/10.1099/00207713-50-4-1505 doi:10.1099/00207713-50-4-1505]</ref> || [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]] || [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]|| [[File:Circle black fill.PNG|15px]] [[File:Circle dark round-middle white.PNG|15px]]
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| − | | colspan="12" style="color:black;text-align:left;"|Notes:
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| − | | colspan="12" style="color:black;text-align:left;"|[[File:Circle black fill.PNG|15px]] Well documented, process is confirmed to occur.
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| − | | colspan="12" style="color:black;text-align:left;"|[[File:Circle Open.PNG|15px]] Some amount of documentation.
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| − | | colspan="12" style="color:black;text-align:left;"|[[File:Circle dark round-middle white.PNG|15px]] Only select compounds may undergo these processes.
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| − | | colspan="12" style="color:black;text-align:left;"|[[File:Circle with diagnal line.PNG|15px]] Not routinely documented.
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| − | | colspan="12" style="color:black;text-align:left;"| Table 1. Biodegradation processes for perchlorate and common organic contaminants.
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| − | {| class="wikitable"
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| − | ! Metal/Metalloid!! Oxidation States<sup>a</sup> !! Aerobic oxidation!! Anaerobic reduction!! ISP via SRB<sup>b</sup>
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| − | | colspan="12" style="color:black;text-align:center;"| Oxyanions
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| − | | Arsenic<ref>Katsoyiannis, I.A. and Zouboulis, A.I., 2004. Application of biological processes for the removal of arsenic from groundwaters. Water Research, 38(1), pp.17-26. [https://doi.org/10.1016/j.watres.2003.09.011 doi 10.1016/j.watres.2003.09.011]</ref><ref>Keimowitz, A.R., Mailloux, B.J., Cole, P., Stute, M., Simpson, H.J. and Chillrud, S.N., 2007. Laboratory investigations of enhanced sulfate reduction as a groundwater arsenic remediation strategy. Environmental Science & Technology, 41(19), pp.6718-6724. [https://doi.org/10.1021/es061957q doi 10.1021/es061957q]</ref><ref>Onstott, T.C., Chan, E., Polizzotto, M.L., Lanzon, J. and DeFlaun, M.F., 2011. Precipitation of arsenic under sulfate reducing conditions and subsequent leaching under aerobic conditions. Applied Geochemistry, 26(3), pp.269-285. [https://doi.org/10.1016/j.apgeochem.2010.11.027 doi 10.1016/j.apgeochem.2010.11.027]</ref>|| As ('''III, V''')|| [[File:Circle black fill.PNG|15px]]<sup>c</sup> || [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]
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| − | | Chromium<ref>Jeyasingh, J., Somasundaram, V., Philip, L. and Bhallamudi, S.M., 2011. Pilot scale studies on the remediation of chromium contaminated aquifer using bio-barrier and reactive zone technologies. Chemical Engineering Journal, 167(1), pp.206-214.[ https://doi.org/10.1016/j.cej.2010.12.024 doi 10.1016/j.cej.2010.12.024]</ref><ref>Freese, K., Miller, R., J Cutright, T. and Senko, J., 2014. Review of Chromite Ore Processing Residue (COPR): Past Practices, Environmental Impact and Potential Remediation Methods. Current Environmental Engineering, 1(2), pp.82-90. [https://doi.org/10.2174/221271780102141117101551 doi 10.2174/221271780102141117101551]</ref>|| Cr (III, '''VI''')|| [[File:Circle with diagnal line.PNG|15px]] || [[File:Circle black fill.PNG|15px]]<sup>d</sup>|| [[File:Circle black fill.PNG|15px]]
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| − | | Selenium<ref>Hunter, W.J. and Kuykendall, L.D., 2005. Removing selenite from groundwater with an in situ biobarrier: laboratory studies. Current Microbiology, 50(3), pp.145-150. [https://doi.org/10.1007/s00284-004-4418-0 doi 10.1007/s00284-004-4418-0]</ref>|| Se (-II, 0, IV, '''VI''')|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]<sup>e</sup>|| [[File:Circle with diagnal line.PNG|15px]]
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| − | | Uranium<ref>Anderson, R.T., Vrionis, H.A., Ortiz-Bernad, I., Resch, C.T., Long, P.E., Dayvault, R., Karp, K., Marutzky, S., Metzler, D.R., Peacock, A. and White, D.C., 2003. Stimulating the in situ activity of Geobacter species to remove uranium from the groundwater of a uranium-contaminated aquifer. Applied and Environmental Microbiology, 69(10), pp.5884-5891. [https://doi.org/10.1128/aem.69.10.5884-5891.2003 doi 10.1128/aem.69.10.5884-5891.2003]</ref><ref>Finneran, K.T., Anderson, R.T., Nevin, K.P. and Lovley, D.R., 2002. Potential for bioremediation of uranium-contaminated aquifers with microbial U (VI) reduction. Soil and Sediment Contamination: An International Journal, 11(3), pp.339-357. [https://doi.org/10.1080/20025891106781 doi 10.1080/20025891106781]</ref>|| U (IV, '''VI''')|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]<sup>e</sup>||[[File:Circle black fill.PNG|15px]]
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| − | | colspan="12" style="color:black;text-align:center;"| Metal Cations Notes:
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| − | | Iron<ref name="Dvorak1992">Dvorak, D.H., Hedin, R.S., Edenborn, H.M. and McIntire, P.E., 1992. Treatment of metal‐contaminated water using bacterial sulfate reduction: Results from pilot‐scale reactors. Biotechnology and Bioengineering, 40(5), pp.609-616. [https://doi.org/10.1002/bit.260400508 doi 10.1002/bit.260400508]</ref><ref name= "Dreverj">Drever, J.I., The Geochemistry of Natural Waters: Surface and Groundwater Environments. Prentice-Hall, Inc., ISBN 0132727900.</ref>|| '''Fe<sup>2+</sup>''', Fe<sup>3+ </sup>|| [[File:Circle black fill.PNG|15px]]<sup>f</sup>|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]
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| − | | Manganese<ref name="Dvorak1992"/><ref name= "Dreverj"/>|| '''Mn<sup>2+</sup>''', Mn<sup>4+</sup>|| [[File:Circle black fill.PNG|15px]]<sup>f</sup>|| [[File:Circle with diagnal line.PNG|15px]]|| [[File:Circle black fill.PNG|15px]]
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| − | | Lead, Copper, Cobalt, Nickel, Cadmium, Zinc, Mercury<ref>Blowes, D.W., Ptacek, C.J., Benner, S.G., McRae, C.W., Bennett, T.A. and Puls, R.W., 2000. Treatment of inorganic contaminants using permeable reactive barriers. Journal of Contaminant Hydrology, 45(1), pp.123-137.</ref><ref>Hashim, M.A., Mukhopadhyay, S., Sahu, J.N. and Sengupta, B., 2011. Remediation technologies for heavy metal contaminated groundwater. Journal of Environmental Management, 92(10), pp.2355-2388.</ref>|| '''Me<sup>2+</sup>'''|| NA|| NA|| [[File:Circle black fill.PNG|15px]]
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| − | | colspan="12" style="color:black;text-align:left;"|Notes:
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| − | | colspan="12" style="color:black;text-align:left;"|[[File:Circle black fill.PNG|15px]] Well documented immobilization mechanism.
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| − | | colspan="12" style="color:black;text-align:left;"|[[File:Circle with diagnal line.PNG|15px]] Not a documented immobilization mechanism.
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| − | | colspan="12" style="color:black;text-align:left;"|NA - Not applicable.
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| − | | colspan="12" style="color:black;text-align:left;"|a - Found in soil and groundwater, '''bold''' indicates oxidation states of dissolved/mobile species.
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| − | | colspan="12" style="color:black;text-align:left;"| b - In-situ precipitation and co-precipitation as sulfides mediated by sulfate reducing bacteria.
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| − | | colspan="12" style="color:black;text-align:left;"| c - Microbial oxidation of As(III) to As(V) followed by enhanced adsorption of As(V) onto iron and manganese oxides/hydroxides.
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| − | | colspan="12" style="color:black;text-align:left;"| d - Microbial reduction of Cr(VI) to less mobile Cr(III), followed by mineral precipitation and co-precipitation with Fe as oxide or oxyhydroxides.
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| − | | colspan="12" style="color:black;text-align:left;"| e - Microbial reduction, followed by precipitation and/or adsorption onto mineral phases.
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| − | | colspan="12" style="color:black;text-align:left;"| f - Microbial oxidation to Fe<sup>3+</sup> or Mn<sup>4+</sup> followed by precipitation as oxides/hydroxides.
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| − | | colspan="12" style="color:black;text-align:left;"|Table 2. Microbial-based immobilization mechanisms for common metals and metalloids in groundwater.
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| − | ==Technology Acceptance==
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| − | Bioremediation is widely applied for remediation of recalcitrant compounds present in soil and/or groundwater, and is often chosen as it can be a less expensive, adaptable to site-specific conditions, and more sustainable choice to achieve remedial goals<ref name="Stroo2010">Stroo, H.F. and Ward, C.H. eds., 2010. In situ remediation of chlorinated solvent plumes. Springer Science & Business Media. [https://doi.org/10.1007/978-1-4419-1401-9 doi 10.1007/978-1-4419-1401-9]</ref>. Multiple guidance documents are available that describe design and implementation considerations, and results from applications around the globe. This includes guidance from the United States Environmental Protection Agency (USEPA)<ref name= "USEPA2013Intro"/>, the United States Air Force, Navy and Environmental Security Technology Certification Program (ESTCP)<ref>Air Force Center for Environmental Excellence, Naval Facilities Engineering Service Center, and ESTCP, 2004. Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents. ADA511850.</ref><ref name= "NAVFAC2015D"/>, and the Interstate Technology and Regulatory Council (ITRC)<ref name= "TRC2008">ITRC, 2008. In Situ Bioremediation of Chlorinated Ethene: DNAPL Source Zones. June, 2008</ref>.
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| − | ==Technology Selection and Design Considerations==
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| − | The selection and '''design of an anaerobic bioremediation''' remedy should include the following factors<ref name= "USEPA2013Intro"/><ref name ="Stroo2010"/><ref name= "TRC2008"/><ref>USEPA, 2010. Green Remediation Best Management Practices: Bioremediation. EPA 542-F-10-006 [http://www.environmentalrestoration.wiki/images/9/99/gr_factsheet_biorem_32410.pdf Report pdf]</ref>:
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| − | *'''Contaminant Treatability'''. Consider whether the target contaminants, as well as any potential co-contaminants, can be effectively treated by anaerobic bioremediation.
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| − | *'''Remediation of Source Zones'''. Anaerobic bioremediation has been shown a viable remedial approach for dissolved contaminant mass, and for limiting mass flux from source zones containing dense non-aqueous phase liquid ('''DNAPL'''). Treatment of DNAPL mass in source zones has also been demonstrated, but the remedial timeframe is typically longer than applications were aqueous phase concentrations are targeted<ref name= "TRC2008"/><ref>Cope, N. and Hughes, J.B., 2001. Biologically-enhanced removal of PCE from NAPL source zones. Environmental Science & Technology, 35(10), pp.2014-2021. [https://doi.org/10.1021/es0017357 doi 10.1021/es0017357]</ref><ref>Yang, Y. and McCarty, P.L., 2002. Comparison between donor substrates for biologically enhanced tetrachloroethene DNAPL dissolution. Environmental Science & Technology, 36(15), pp.3400-3404. [https://doi.org/10.1021/es011408e doi 10.1021/es011408e]</ref><ref>CL:AIRE, 2010. Results of Laboratory Column Studies to Determine the Potential for Bioremediation of Chlorinated Solvent DNAPL Source Areas. SABRE Bulletin 3.</ref><ref>Moretti, L., 2005. In situ bioremediation of DNAPL Source Zones. US Environmental Protection Agency, Office of Solid Waste and Emergency Response, Technology Innovation and Field Services Division.</ref>.
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| − | *'''Site Conditions'''. Low permeability and/or high heterogeneity of the targeted formation may limit amendment distribution or influence remedy design. This limitation is common to all in-situ remediation approaches and can be addressed by selection of an appropriate installation method.
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| − | *'''Incomplete biodegradation'''. Creation and/or accumulation of breakdown products (e.g., cis-1,2-dichloroethene and vinyl chloride from tetrachloroethene [PCE] and TCE) may occur. In many cases, the design of an EISB remedy can address these concerns by incorporating monitoring to confirm the effects are temporary and introducing additional amendments (pH buffers, bioaugmentation cultures) to prevent accumulation of breakdown products.
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| − | *'''Potential Process Inhibition'''. Geochemical conditions (e.g., high/low pH levels) and intrinsic toxicity due to presence of elevated concentration of inhibitors such as metals, chloroform, other organic co-contaminants (e.g., 1,1,1,-trichloroethane) or sulfide should be evaluated and potential mitigation approaches considered.
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| − | *'''Secondary Effects on Water Quality '''. Changes in pH and redox conditions in an anaerobic bioremediation zone may mobilize metals (e.g., iron, manganese, and arsenic) and form undesirable fermentation products (e.g., aldehydes and ketones). The design and monitoring program for a bioremediation remedy should account for these potential secondary effects.
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| − | *'''Volatile Byproducts '''. Stimulation of anaerobic biodegradation may enhance generation of gases (e.g., vinyl chloride, methane, or hydrogen sulfide) that may degrade groundwater quality and/or accumulate in the vadose zone. Optimization of system designs can mitigate and monitor these effects (e.g., use of lower electron donor rates to limit methanogenesis, use of bioaugmentation to prevent vinyl chloride formation, and use of soil gas monitoring).
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| − | *'''Cost'''. Amendment material and implementation cost as compared to other viable remediation approaches (e.g., ''' in situ chemical reduction (ISCR), in situ chemical oxidation (ISCO) ''').
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| − | *'''Timeframe for Remediation'''. Development of microbial populations capable of complete degradation of target contaminants may require several months to years. While bioremediation may take longer than other remedial approaches (e.g., '''ISCO, in situ thermal remediation'''), this is frequently balanced by lower cost, higher sustainability and reduced likelihood of rebound following remediation.
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| − | *'''Sustainability'''. Anaerobic bioremediation frequently uses less electricity and water than many other remedial alternatives, and uses non-toxic amendments, which make it desirable as a sustainable remedial tool. In situ applications avoid transport of materials off-site to disposal facilities.
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| − | ==Biostimulation==
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| − | [[File:MacKinnon AnBiorem Fig1.jpg|thumbnail|right|Figure 1. Redox ladder for common electron donors and electron acceptors.]]
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| − | Biostimulation means adding compounds to the subsurface to encourage indigenous microorganisms to metabolize target contaminants<ref name= "USEPA2013Intro"/>. In anaerobic reductive processes, simple organic carbon compounds (e.g., sugars, alcohols, aliphatic hydrocarbons, and volatile fatty acids) serve as electron donors to stimulate anaerobic bacterial growth, and thus enhance the rate and extent of biodegradation of the target contaminants. For anaerobic oxidative processes, it may be necessary to add electron acceptors, such as nitrate or sulfate to enhance biodegradation. A crucial component of the '''design''' of anaerobic bioremediation systems is selection of appropriate '''amendments''', and their '''application dosages'''.
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| − |
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| − | In the case of electron donors, the '''amendments''' used in bioremediation applications are typically classified as quick release compounds (lactate, sodium benzoate, molasses, whey) or slow release compounds (emulsified vegetable oils, HRC<sup>®</sup>, EHC<sup>®</sup>, ABC<sup>®</sup>+, mulch, compost). These electron donors are added in anaerobic bioremediation to stimulate conditions conducive to the degradation processes by depleting the dissolved oxygen (DO), and other terminal electron acceptors, and lowering the oxidation-reduction potential of groundwater. In addition, products of electron donor fermentation (i.e., simple organic acids, hydrogen) are required as an energy source for metabolism of decontaminating microbes. The amount of energy released during electron transfer from the donor is controlled by the redox potential (Eh) of the terminal electron acceptor. Therefore, anaerobic microorganisms typically use available native electron acceptors in the following order of preference: nitrate, manganese and ferric iron oxyhydroxides, sulfate, and finally carbon dioxide (Fig. 1).
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| − |
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| − | '''Reductive dechlorination''' of more highly halogenated organics such as PCE and TCE to dichloroethene (DCE) can occur under mildly reducing nitrate or iron reducing conditions<ref>Wei, N. and Finneran, K.T., 2011. Influence of ferric iron on complete dechlorination of trichloroethylene (TCE) to ethene: Fe (III) reduction does not always inhibit complete dechlorination. Environmental Science & Technology, 45(17), pp.7422-7430. [https://doi.org/10.1021/es201501a doi 10.1021/es201501a]</ref>; however, the complete reductive dechlorination of the widest range of the targeted compounds (including degradation of DCE to ethene) often occurs under more strongly reducing conditions of sulfate reduction or methanogenesis<ref>Vogel, T.M., Criddle, C.S. and McCarty, P.L., 1987. ES&T critical reviews: transformations of halogenated aliphatic compounds. Environmental Science & Technology, 21(8), pp.722-736. [http://dx.doi.org/10.1021/es00162a001 doi:10.1021/es00162a001]</ref>. Lightly halogenated organics such as vinyl chloride have also been demonstrated to undergo anaerobic oxidation under iron reducing conditions<ref>Bradley, P.M. and Chapelle, F.H., 1996. Anaerobic mineralization of vinyl chloride in Fe (III)-reducing, aquifer sediments. Environmental Science & Technology, 30(6), pp.2084-2086. [https://doi.org/10.1021/es950926k doi 10.1021/es950926k]</ref>. Therefore, the optimal anaerobic conditions for complete dechlorination occurs after the competing electron acceptors such as DO, nitrate, and manganese are consumed.
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| − | ==Bioaugmentation==
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| − | [[File:MacKinnon AnBiorem Fig2.jpg|thumbnail|right|Figure 2. Example of bioaugmentation at a field site.]]
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| − | Bioaugmentation may be considered at a site when an appropriate population of anaerobic microorganisms is not present or sufficiently active to stimulate complete anaerobic degradation of the existing contaminants. While microorganisms necessary for complete biodegradation of some contaminants (i.e., perchlorate) can be fairly widespread, this is not always the case. In these cases, bioaugmentation is used to enhance bioremediation. Bioaugmentation involves the injection of microbial cultures comprised of non-native organisms known to degrade the targeted contaminants to completion (Fig. 2). For example, the presence of Dehalococcoides-related microorganisms has been linked to complete dechlorination of PCE and TCE to ethene in the field<ref>Parsons, 2004. Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents. AFCEE, NFEC, ESTCP [http://www.environmentalrestoration.wiki/images/d/d5/AFCEE_Principles_and_Practices.pdf Report pdf]</ref><ref>Major, D.W., McMaster, M.L., Cox, E.E., Edwards, E.A., Dworatzek, S.M., Hendrickson, E.R., Starr, M.G., Payne, J.A. and Buonamici, L.W., 2002. Field demonstration of successful bioaugmentation to achieve dechlorination of tetrachloroethene to ethene. Environmental Science & Technology, 36(23), pp.5106-5116. [https://doi.org/10.1021/es0255711 doi 10.1021/es0255711]</ref><ref>Hendrickson, E.R., Payne, J.A., Young, R.M., Starr, M.G., Perry, M.P., Fahnestock, S., Ellis, D.E. and Ebersole, R.C., 2002. Molecular analysis of Dehalococcoides 16S ribosomal DNA from chloroethene-contaminated sites throughout North America and Europe. Applied and Environmental Microbiology, 68(2), pp.485-495. [https://doi.org/10.1128/aem.68.2.485-495.2002 doi 10.1128/aem.68.2.485-495.2002]</ref><ref>Lendvay, J.M., Löffler, F.E., Dollhopf, M., Aiello, M.R., Daniels, G., Fathepure, B.Z., Gebhard, M., Heine, R., Helton, R., Shi, J. and Krajmalnik-Brown, R., 2003. Bioreactive barriers: a comparison of bioaugmentation and biostimulation for chlorinated solvent remediation. Environmental Science & Technology, 37(7), pp.1422-1431. [https://doi.org/10.1021/es025985u doi 10.1021/es025985u]</ref>. Commercially available bioaugmentation products that contain these microorganisms include KB-1<sup>®</sup>, SDC-9™, and Bio-Dechlor Inoculum<sup>®</sup> Plus.
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| − | ==Summary & Conclusions==
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| − | Anaerobic bioremediation is a well-demonstrated remediation strategy for the treatment of a wide range of organic contaminants, most notably chlorinated solvents. The injection of carbon-based electron donors for biostimulation and microbial cultures for bioaugmentation can promote the complete anaerobic biodegradation of contaminants in soil and groundwater.
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| − |
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| − | There have been numerous field demonstrations of anaerobic bioremediation documented in publicly available literature and reports, including:
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| − | *U.S. EPA Contaminated Site Clean-Up Information (CLU-IN)<ref>USEPA 2016. Anaerobic Bioremediation (Direct) Application.</ref>
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| − | *In Situ Bioremediation of Chlorinated Ethene DNAPL Source Zones: Case Studies<ref name= "ITRC2007">ITRC, 2007. In Situ Bioremediation of Chlorinated Ethene DNAPL Source Zones: Case Studies, BioDNAPL-2, 173 pp, 2007 [http://www.environmentalrestoration.wiki/images/5/5a/ITRC-2007-Bioremed_of_Chlorinated_Ethene.pdf Report pdf]</ref>
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| − | *ESTCP Demonstrations: Cost and Performance Reports
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| − | **ER-0008 - Biodegradation of Dense Non-Aqueous Phase Liquids (DNAPLs) through Bioaugmentation of Source Areas - Dover National Test Site<ref>ESTCP, 2008. Biodegradation of Dense Non-Aqueous Phase Liquids (DNAPLs) through Bioaugmentation of Source Areas - Dover National Test Site, Dover, Delaware: ESTCP Cost and Performance Report. [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Persistent-Contamination/ER-200008/ER-200008 ESTCP Project ER-0008]</ref>
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| − | **ER-0221 - Edible Oil Barriers for Treatment of Chlorinated Solvent Groundwater<ref>Lieberman, M.T. and Borden, R.C., 2009. Edible Oil Barriers for Treatment of Chlorinated Solvent Contaminated Groundwater. Solutions Industrial and Environmental Services Raleigh, NC. [http://www.environmentalrestoration.wiki/images/4/45/PRB-ER-0221-FR.pdf Report pdf]</ref>
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| − | **ER-200219 - Comparative Demonstration of Active and Semi-Passive In Situ Bioremediation Approaches for Perchlorate Impacted Groundwater: Active In Situ Bioremediation Demonstration (Aerojet Facility)<ref name= "Cox2012">Cox, E. and Krug, T., 2012. Comparative Demonstration of Active and Semi-Passive In Situ Bioremediation Approaches for Perchlorate Impacted Groundwater: Active In Situ Bioremediation Demonstration (Aerojet Facility) ESTCP Project ER-200219. [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-200219 ER-200219]</ref>
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| − | **ER-200627 - Loading Rate and Impacts of Substrate Delivery for Enhanced Anaerobic Bioremediation<ref name= "ESTCP2010LR">ESTCP, 2010. Loading Rate and Impacts of Substrate Delivery for Enhanced Anaerobic Bioremediation. ESTCP Project ER-200627, 90 pp. [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/ER-200627 ER-200627]</ref>
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| − | *Regulatory / Guidance Documents<ref name= "ITRC2007"/><ref name= "Cox2012"/><ref name= "ESTCP2010LR"/><ref>Robinson, C., Barry, D.A., McCarty, P.L., Gerhard, J.I. and Kouznetsova, I., 2009. pH control for enhanced reductive bioremediation of chlorinated solvent source zones. Science of the Total Environment, 407(16), pp.4560-4573. [https://doi.org/10.1016/j.scitotenv.2009.03.029 doi 10.1016/j.scitotenv.2009.03.029]</ref><ref>Borden, R.C., Cha, K.Y., Simpkin, T. and Lieberman, M.T., 2012. Development of a Design Tool for Planning Aqueous Amendment Injection Systems Soluble Substrate Design Tool (No. ER-200626). North Carolina State Univ. at Raleigh. [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/ER-200626/ER-200626 Report pdf]</ref>
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| − |
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| − | On-going research and development for bioremediation includes the following SERDP / ESTCP projects:
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| − | *ER-201428 - Long-Term Performance Assessment at a Highly Characterized and Instrumented DNAPL Source Area following Bioaugmentation
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| − | *ER-2311 - Development of an Integrated Field Test/Modeling Protocol for Efficient In Situ Bioremediation Design and Performance Uncertainty Assessment
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| − | *ER-2312 - Advanced Environmental Molecular Diagnostics to Assess, Monitor, and Predict Microbial Activities at Complicated Chlorinated Solvent Sites
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| − | *ER-201325 - Electrokinetic-Enhanced (EK-Enhanced) Amendment Delivery for Remediation of Low Permeability and Heterogeneous Materials
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| − | *ER-2530- Biogeochemical Processes that Control Natural Attenuation of Trichloroethylene in Low Permeability Zones
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| − | *ER-2532 - Biologically Mediated Abiotic Degradation of Chlorinated Ethenes: A New Conceptual Framework
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| − | *ER-201581 - Post-Remediation Evaluation of EVO Treatment - How Can We Improve Performance?
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| − | *ER-201629 - Evaluation of a Sustainable and Passive Approach to Treat Large, Dilute Chlorinated VOC Groundwater Plumes
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| | ==References== | | ==References== |
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| | ==See Also== | | ==See Also== |
| − | *[https://clu-in.org/techfocus/default.focus/sec/Bioremediation/cat/Anaerobic_Bioremediation_(Direct)/p/2 Bioremediation]
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| − | *[https://clu-in.org/download/contaminantfocus/dnapl/Treatment_Technologies/epa_2006_engin_issue_bio.pdf In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites]
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| − | *[https://clu-in.org/download/remed/Bioaug2005.pdf Bioaugmentation For Remediation of Chlorinated Solvents]
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| − | *[https://frtr.gov/costperformance/pdf/remediation/principles_and_practices_bioremediation.pdf Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents]
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| − | *[http://www.itrcweb.org/Team/Public?teamID=23 Bioremediation of DNAPLs]
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| − | *[http://www.itrcweb.org/Team/Public?teamID=33 In Situ Bioremediation]
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| − | *[http://navfac.navy.mil/content/dam/navfac/Specialty%20Centers/Engineering%20and%20Expeditionary%20Warfare%20Center/Environmental/Restoration/er_pdfs/b/navfac-ev-fs-biorem-dnapl-20120412.pdf Using Bioremediation in Dense Non-Aqueous Phase Liquid Source Zones]
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| − | *[http://navfac.navy.mil/content/dam/navfac/Specialty%20Centers/Engineering%20and%20Expeditionary%20Warfare%20Center/Environmental/Restoration/er_pdfs/d/navfacexwc-ev-tm-1501-erd-design-201503f.pdf Design Considerations for Enhanced Reductive Dechlorination]
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| − | *[https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/ER-200626 Development of Design Tools for Planning Aqueous Amendment Injection Systems]
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