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. David Ladner

Committee Member

Dr. Sudeep Popat

Abstract

Chlorinated solvents have been a contaminant of interest in the remediation field for many years because they have been manufactured in large amounts and released into the environment due to improper storage and disposal. Since they are produced in such large quantities and there has been so many cases of uncontrolled releases, corrective actions are necessary and many remediation strategies have been explored. In-situ bioremediation of chlorinated solvents (TCE) is an intricate respiratory process which combines the addition of electron donors, chemical reactions, and the presence of microorganisms which directly access contaminants. Microbes metabolize the electron donor and utilize the energy for complete dechlorination of TCE to ethene. Vendors suggest the addition of activated carbon to the system should be used to provide an absorptive surface for both contaminants and microbes and is thought to act as an electron shuttle to increase the rate of reduction.

Each microcosm was set up in triplicate with TCE contaminated sediment and surface water from the same site, an electron donor amendment (lactate, acetate + hydrogen, or emulsified oil substrate (EOS)), 20umol of neat TCE, and activated carbon. For both granular activated carbon (GAC) and powdered activated carbon (PAC) the high mass loading rate, suggested by the vendor, was added at 78 mg/mL of water and the low mass loading rate was added at 26 mg/mL of water, one-third the suggested amount. Each electron donor amended series was evaluated at high and low loading rates of GAC and PAC as well as a no activated carbon control. There were also 2 additional controls, a no amendment series control and sterile series control. A gas chromatograph (GC) was used to determine the mass of TCE, its dechlorination products, and methane present in each microcosm. Data suggest that the series with low PAC and no activated carbon have the most dechlorinating activity regardless of the electron donor amendment and the series with high mass loading of GAC and PAC are showing no dechlorination. However, amongst the amendments, EOS is showing the highest activity but it is also producing more methane than any other amendment.

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