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In Situ Perchlorate DegradationState College, PASource: Gillespie, Rick, and Stephen Koenigsberg, 2000. "Time-Release Electron Donor Technology for the Accelerated Bioremediation of Perchlorate" in Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention & Hazardous Waste Management Conference & Exhibition, August 21-24, 2000, Henry B. Gonzalez Convention Center, San Antonio, Texas. The Pennsylvania State University website of Dr. Bruce E. Logan - Ongoing research topics and topical webpage links, available at http://www.engr.psu.edu/ce/enve/logan.htm. Project Summary: The following text was excerpted from The Pennsylvania State University website of Dr. Bruce E. Logan - Ongoing research topics and topical webpage links, available at http://www.engr.psu.edu/ce/enve/logan.htm; and, Gillespie, Rick, and Stephen Koenigsberg, 2000. "Time-Release Electron Donor Technology for the Accelerated Bioremediation of Perchlorate" in Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention & Hazardous Waste Management Conference & Exhibition, August 21-24, 2000, Henry B. Gonzalez Convention Center, San Antonio, Texas: Part of the recalcitrance of perchlorate in groundwater may be a result of the lack of suitable conditions for in situ degradation. Therefore, researchers at Penn State are investigating methods to stimulate in situ degradation by determining if perchlorate reduction is limited by one of three factors: insufficient microorganisms in the soil capable of perchlorate degradation; lack of anaerobic conditions; lack of sufficient oxidizable substrate (i.e. insufficient electron donor). The abundance of chlorate and perchlorate reducing microorganisms (CRMs and PRMs) is being examined as a part of an ongoing NSF grant. The effect of anaerobic conditions and the importance of sufficient electron acceptors is being examined by determining the effect of lactate on perchlorate degradation. A significant body of literature supports the validity of enhancing biological reductive dechlorination with organic substrates that serve as electron donors. Typically, substrates are fermented to produce an electron donor such as hydrogen, which in turn can be used in the benign transformation of chlorinated hydrocarbons and oxyanions such as nitrate and perchlorate. Implementation of an appropriate time-release electron donor system can eliminate major design, capital and operational costs, is minimally invasive and is invisible during the working phase. Hydrogen Release Compound (HRC™) has been developed by Regnesis Bioremediation Products as a lowcost treatment option for in-situ anaerobic bioremediation of chlorinated aliphatic hydrocarbons (CAHs). HRC is a proprietary, environmentally safe, food quality, polylactate ester specially formulated for slow release of lactic acid upon hydration. HRC® releases lactic acid for up to one year. Bioremediation with HRC is a multistep process. Indigenous anaerobic microbes (such as acetogens) metabolize the lactic acid released by HRC® as a nutrient source, and produce hydrogen. The resulting hydrogen can be used by reductive dehalogenators which are capable of dechlorinating CAHs. Major target compounds in this group include PCE, TCE, and TCA as well as their daughter products. By providing a long-lasting, time-released hydrogen source, HRC® can enhance anaerobic reductive dechlorination of chlorinated aliphatic hydrocarbons. HRC® is injected into the aquifer using direct-push technology, or bore-hole backfill, and is a moderately flowable material that facilitates passive treatment of dissolved phase plumes. Through a gift by Regenesis to Bruce Logan's research efforts, researchers have investigated whether HRC® can be used to support biological perchlorate reduction. Batch tests were conducted with pure and mixed cultures to demonstrate biological perchlorate reduction in comparison to abiotic and non-amended controls. Further experiments were planned with packed soil columns to demonstrate long term efficiency of the HRC® in supporting in situ perchlorate degradation. HRC® has been used in a large number of chlorinated hydrocarbon laboratory experiments and field applications. In these studies the reduction of the nitrate oxyanion is duly noted. Full details can be found at www.regenesis.com. With respect to oxyanions such as perchlorate, Regenesis supported laboratory studies that were eventually published by Logan et al. Regenesis is now poised to bring these results to the field in a series of trials, to test the hypothesis by Logan that HRC® as well as lactate can be an effective method for stimulating in situ reduction of perchlorate. Additional Info Source: Gillespie, Rick, and Stephen Koenigsberg, 2000. "Time-Release Electron Donor Technology for the Accelerated Bioremediation of Perchlorate" in Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention & Hazardous Waste Management Conference & Exhibition, August 21-24, 2000, Henry B. Gonzalez Convention Center, San Antonio, Texas. Logan, B.E., H. Zhang, J. Wu, R. Unz, and S.S. Koenigsberg, 2000. The Potential for In Situ Perchlorate Degradation In: Case Studies in the Remediation of Chlorinated and Recalcitrant Compounds, G.B. Wickramanayake, A.R. Gavaskar, J.T. Gibbs, and J.L. Means, eds., Battelle Press, Columbus, OH, pp. 87-92. The Pennsylvania State University website of Dr. Bruce E. Logan - Ongoing research topics and topical webpage links, available at http://www.engr.psu.edu/ce/enve/logan.htm. |
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