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METHODOLOGIES FOR EVALUATING IN-SITU BIOREMEDIATION OF CHLORINATED SOLVENTS
Citation:
Semprini, L., D. GrbicGalic, P. L. McCarty, AND P. V. Roberts. METHODOLOGIES FOR EVALUATING IN-SITU BIOREMEDIATION OF CHLORINATED SOLVENTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-92/042 (NTIS 92-146943), 1992.
Impact/Purpose:
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Description:
This report summarizes the behavior of and requisite conditions for a class of natural biological processes that can transform chlorinated aliphatic compounds. These compounds are among the most prevalent hazardous chemical contaminants found in municipal and industrial wastewaters, landfills and landfill leachates, industrial disposal sites, and groundwater. Biological degradation is one approach that has the potential for destroying hazardous chemicals so that they can be rendered harmless for all time. Methodologies are presented that are useful for evaluating the potential for biorestoration of groundwater contaminated with chlorinated aliphatic compounds. The report is composed of six sections. Section 1 provides an introduction and an overview of the problems with chlorinated aliphatic compounds in groundwater. Section 2 presents a review of the processes affecting the movement and fate of chlorinated aliphatics in the subsurface, including advection, dispersion, sorption and relative mobility, diffusional transport, and immiscible transport. Section 3 provides a thorough review of the microbial transformation of organic pollutants. Basic microbial metabolic processes are reviewed, focusing on an aerobic and aerobic transformations of chlorinated aliphatic compounds. Laboratory studies of aerobic cometabolic transformation and degradation of TCE by methanotrophs and methanotrophic communities are summarized. In Section 4 transport and microbial process models are presented and incorporated into a model for the aerobic cometabolic transformation of chlorinated aliphatics by methanotrophic communities. Section 5 presents pilot-scale results of enhanced in-situ biotransformation of halogenated alkenes, including TCE, cis- and trans-DCE, and vinyl chloride by methanotrophic bacteria along with model simulations of the results. Section 6 presents an example study to evaluate the potential and limitations for groundwater bioremediation at a Superfund site by methanotrophs. Methodologies and results are presented for evaluating the presence of a native methanotrophic community and its ability to degrade the contaminants of concern; determining the sorption of contaminants to the aquifer material; and preliminary designing of an in-situ treatment approach using the model previously described.