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Bioremediation/Natural Attenuation Continues after ISCO Treatment
Citation:
HULING, S., D. Brown, AND R. Luhrs. Bioremediation/Natural Attenuation Continues after ISCO Treatment. IN: Technology News and Trends, U.S. EPA Office of Superfund Remediation and Technology Innovation, Washington, DC, (41):7-10, (2009).
Impact/Purpose:
To observe several technical issues that are commonly raised during in-situ chemical oxidation (ISCO)
Description:
Permanganate has been successfully used in in-situ chemical oxidation (ISCO) to transform a wide range of organic contaminants under diverse geologic and geochemical conditions. Here, a critical analysis is presented of several technical issues commonly raised during in-situ chemical oxidation (ISCO) with including permeability reduction by MnO2(s), and post-oxidation impact on biological natural attenuation. Pore filling of aquifer media from precipitation and accumulation of MnO2(s) appears to be an unlikely explanation of permeability reduction. Non-uniform accumulation of MnO2(s), injection of solids (KMnO4(s), MnO2(s), silicates), precipitation of KMnO4(s), and CO2(g) production also cause reductions in permeability. Oxidant are antiseptics and will inhibit and/or kill microbiota at lower concentrations than used in ISCO. Non-ideal contact conditions at field-scale permit soil microbiota to survive rigorous applications of oxidant. The impact of the oxidant on microbial activity is temporary, localized near the injection areas, and given sufficient time after ISCO, the microbial populations, microbial activity, and the rate of biodegradation appears to increase, possibly to levels above pre-oxidation conditions. No known cases were found where aquifer material was sterilized or where microbial activity has been permanently inhibited.
