Date of Award

8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Engineering and Earth Sciences

Committee Member

Dr. Kevin Finneran, Committee Chair

Committee Member

Dr. Ron Falta

Committee Member

Dr. Christophe Darnault

Abstract

Chlorinated solvent bioremediation encompasses a number of combined microbial and chemical reactions that either oxidize or reduce the contaminant(s) of concern. In the case of trichloroethylene (TCE), many approaches rely on adding electron donors to stimulate chlororespiration, in which cells gain energy to grow by sequentially reducing TCE to ethene. In the recent years, the idea that chlorinated solvents could be reduced by inhibiting methane production to stimulate dechlorination has been put into practice by vendors. The theory is that if methane production is inhibited, electrons will be redirected to chlorinated solvent reduction for complete dechlorination. However, if methanogenesis is inhibited, then microbial activity that is key in reducing chlorinated solvents may, or may not, occur. The purpose of this research is to evaluate the influence of methane inhibitors on chlorinated solvents by using electron donors in various concentrations in order to evaluate this process. Electron donors include plant-based essential oils, lactate, and statins. The work demonstrates that inhibiting methanogenesis alone may not expedite dechlorination, and the broader impacts on the total microbial community that is central to reducing TCE to ethene are larger than just this single reaction. Additionally, using electron donor amendments at near stoichiometric concentrations will help control methanogenesis while facilitating complete dechlorination.

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