Microbial fuel cells (MFCs) are a solution to the water-energy nexus as they are able to both treat wastewater and recover energy. This technology would improve the sustainability of wastewater treatment plants such as DC Water Blue Plains, which discharges treated water into the Potomac River. The objective of this study was to determine which location within the treatment process would provide the optimal substrate for a MFC. Four locations were selected based on their range in wastewater characteristics. Generation of electric potential, removal of oxygen demand, and diversity of microbial communities tested in laboratory-scale, single-chamber, batch-fed MFCs with aqueous cathodes. The locations tested were Primary Clarifier Effluent, Centrate, Digestate, and Belt Press Filtrate. Filtrate appeared to be the most effective at generating electric potential while removing oxygen demand, generating a maximum of 192.2 mV on the 23rd day of operation. Primary Effluent, Centrate, and Digestate did not generate nearly as much potential in the MFCs; Digestate produced the next highest electric potential which was less than 50% of the maximum potential generated by Filtrate. By the 35th day of treatment, MFCs were able to remove at least 91% of COD in each sample. COD removal in Filtrate over 28-35 days ranged from 58.01-97.8%. BOD removal in Filtrate over 35 days was 75.36%. An increase in TSS was observed and attributed to microbial growth in the MFC. Diverse microbial communities were detected in all samples and were composed predominantly of bacteria from phyla Proteobacteria, Firmicutes, and Bacteroidetes. Filtrate would be a good substrate for MFC treatment because it generates more potential than other substrates while removing the majority of COD and BOD. Oxygen demand is strictly regulated so that wastewater that is returned to the environment contains lower levels of oxygen demand.

Diversity of exoelectrogenic anode biofilm populations and potential for energy recovery using microbial fuel cells in domestic wastewater

254th National Meeting (2017)

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