Push-pull test evaluation of the in situ aerobic cometabolism of chlorinated ethenes by toluene-utilizing microorganisms
نویسنده
چکیده
Single-well, push-pull tests were conducted in a contaminated aquifer to evaluate the ability of toluene-oxidizing microorganisms to cometabolize chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethene (TCE). Test solutions were injected into the aquifer using a standard monitoring well, and then were transported under natural-gradient conditions. Transport tests demonstrated similar transport characteristics of the conservative tracer and the reactive solutes. Biostimulation tests were then performed by injecting a test solution containing dissolved toluene substrate, hydrogen peroxide, bromide, and nitrate in order to increase the biomass of toluene-utilizing microorganisms. Decreases in toluene concentration and the production of o-cresol as an intermediate oxidation product indicated the simulation of toluene-utilizing microorganisms containing an ortho-monooxygenase enzyme. Transformation tests demonstrated that indigenous microorganisms had the capability to transform the surrogate compounds (e.g. isobutene) and both cis-dichloroethene (cis-DCE) and trans-dichloroethene (trans-DCE). Isobutene was transformed to isobutene oxide, indicating transformation by a toluene ortho-monooxygenase, and both cis-DCE and transDCE were transformed. In a final test, the utilization of toluene, and the transformation of isobutene, cisDCE, and trans-DCE were all inhibited in the presence of 1-butyne, a known inhibitor of the toluene orthomonooxygenase enzyme. The method assessed the activity of attached microorganisms under in situ conditions of bioremediation.
منابع مشابه
Evaluation of the in-situ aerobic cometabolism of chlorinated ethenes by toluene-utilizing microorganisms using push-pull tests.
A series of transport, biostimulation, and activity push-pull tests were performed under induced and natural gradient conditions in a trichloroethene (TCE) and cis-dichloroethene (c-DCE) contaminated aquifer. Transport tests demonstrated the feasibility of injecting and recovering complex solute mixtures from the aquifer. During the biostimulation tests, decreases in toluene concentration and t...
متن کامل329-337 Gw M-j 04
Site-specific data are needed to perform feasibility assessments and remedial design for in situ bioremediation of chlorinated aliphatic hydrocarbon (CAH) contamination in ground water. Site-specific data are needed because treatment effectiveness is determined by the metabolic capabilities of native microorganisms, the combinations and concentrations of contaminants, and a variety of other fac...
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Push-pull tests evaluating in situ aerobic cometabolism of ethylene, propylene, and cis-1,2-dichloroethylene.
In situ aerobic cometabolic transformations of ethylene, propylene, and cis-1,2-dichloroethylene (c-DCE), by microorganisms stimulated on propane, were examined in groundwater contaminated with c-DCE and trichloroethylene (TCE). In situ measurements were performed by conducting field push-pull tests, which consisted of injecting site groundwater amended with a bromide tracer and combinations of...
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Research works in the recent past have revealed three major biodegradation processes leading to the degradation of trichloroethylene. Reductive dechlorination is an anaerobic process in which chlorinated ethenes are used as electron acceptors. On the other hand, cometabolism requires oxygen for enzymatic degradation of chlorinated ethenes, which however yields no benefit for the bacteria involv...
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