Identifier

etd-11182010-125539

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

The Scenic Highway area of the PetroProcessors of Louisiana, Inc. (PPI) Superfund site located near Baton Rouge, LA, has groundwater contaminated with a variety of chlorinated alkanes (e.g., 1,2-dichloroethane, 1,2-dichloropropane) and alkenes (e.g., trichloroethene and vinyl chloride). In March 2009, a field-scale pilot test was conducted to evaluate the efficacy of injecting diluted agricultural feed grade molasses into the groundwater in an effort to stimulate in-situ reductive dechlorination of these chlorinated contaminants. Because H2 plays an important role as an electron donor in the metabolism of reductively dechlorinating bacteria, in support of the pilot-scale effort, experiments described in this thesis were conducted to better understand the biological hydrogen production potential of the microbial populations from contaminated groundwater at the site. As a means of evaluating the capacity of microbial populations derived from the site to produce H2 as a potential renewable energy source, additional experiments were carried out to evaluate the rate and yield of hydrogen production using molasses as a feedstock. Batch-mode experiments carried out in a laboratory-scale bioreactor inoculated with groundwater from the PPI site revealed that molasses was rapidly fermented with concomitant H2 production at all pH values tested (ranging from 4.5 to 7.5). In the batch tests, a pH of 5.5 resulted in the highest total production H2 with a net yield of 1.47 mol-H2¬/g-glucose. H2 production rates at higher pH values (6.5 and 7.5) decreased over time due to homoacetogensis and methanogenesis. At a pH of 4.5, H2 production was characterized by lower production rates lasting for a longer period of time. The microbial consortia developed during batch-mode experiments were subsequently employed in continuous-flow (CSTR) experiments to further evaluate the effects of pH on the rate, yield, and stability of H2 production. As with batch-mode experiments, the highest H2 production rate (averaging 8.86 L/L/d over a two-month interval) and yield (1.93 mol-H2/mol-glucoseconsumed) was obtained at pH 5.5. In short-term experiments, supplying elevated concentrations of 1,2-dichloroethane in the bioreactor feed was found to have a slight positive effect on H2 production rate and yield.

Date

2010

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Moe, William M.

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