(477b) Electrically Enhanced Contaminant Degradation in Sediment Caps

In-situ capping is known as an attractive and cost-effective method for remediation of contaminated sediments. Sediment caps with bioremediation will ultimately significantly improve it performance, but reports about methods to enhance contaminant degradation in sediment caps still very little. Electrically enhanced bioactive barrier （BIOLANCE）is a new process for in situ remediation reducible compounds in soil or sediments. Chlorinated benzenes are significant contaminants to environment.

Many chlorinated organic compounds are persistent organic pollutants due to their resistance to biodegradation and chemical degradation. The objective of this study was to determine if electrodes placed in sediment and poised at several volts could create a redox gradient and provide electron acceptor/donor to stimulate chlorinated contaminant degradation, which will prepare for sediment caps application. The results demonstrated that choose graphite as electrodes can lead to sustainable evolution of hydrogen. Hydrogen evolution displayed zero-order kinetics with the time in the initial stages in different voltage. Even high voltage can produce more hydrogen, but it can not keep longer time because the overpotentials on electrode surfaces will prevent its function. In our experiments, 4V is the best choice. At this condition, the redox and pH change were detected. It is possible that reductive dechlorination could have been achieved with lower redox potentials in the presence of enough hydrogen electron donors through electrodes. Just while sulfate reducing or the other favorable electron acceptor may have reducing priority than chlorinated compounds. The experiments of T-cell capping biodechlorination use electrodes will be further studied.