Master of Science in Civil Engineering (MSCE)
Civil and Environmental Engineering
A continuous-flow system composed of two anaerobic bioreactor (ABR) columns (based on engineered wetland systems) connected in series was tested to observe the ability of such a system to treat multiple volatile organic compounds (VOCs) possessing suspected inhibitory effects on the dechlorination of other compounds with cis-1,2-dichloroethylene (cDCE) and 1,1-dichloroethane (1,1-DCA) as the main test chemicals. Following the establishment of cDCE and 1,1-DCA dechlorinating ability at baseline conditions, system perturbations of breakthrough and starvation were conducted to measure the response and recovery of the system dechlorination. In all column experiments, it was observed cDCE dechlorination inhibited the dechlorination of 1,1-DCA and that 1,1-DCA dechlorination proceeded only when cDCE had been degraded to ethene. The largest 1,1-DCA dechlorination was observed near the effluent of the second ABR due to conditions favoring a higher population of 1,1-DCA degrading bacteria. Core samples taken near the influent and effluent zones of the second ABR were tested on the ability to dechlorinate cDCE and 1,1-DCA to investigate the spatial distribution of dechlorinating bacteria as a function of depth and to determine the possible mechanisms behind the inhibition of 1,1-DCA degradation. From the core samples, a relationship between 1,1-DCA dechlorination and methanogenesis was observed which suggested the inhibition of 1,1-DCA observed in the column experiments may have been a result of hydrogen drawdown caused by cDCE dechlorination. Degradation rate constants of cDCE were found to be equal for both cores suggesting a heterogenic distribution of cDCE-degrading bacteria throughout the column, and that the bacteria responsible for cDCE dechlorination were resistant to adverse conditions.
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Boudreau, Alex, "Degradation and inhibition of chlorinated ethanes and ethenes in a two bed, sequential bioremediation system" (2013). LSU Master's Theses. 1668.