(608c) Evaluation of Usability of Various Real Wastewaters in Microbial Fuel Cells

Microbial fuel cells (MFC) have been investigated for years as an alternative for wastewater treatment for reuse, recycle, or discharge with the benefit of energy generation. As any other fuel cell, MFC convert a chemical "fuel" into electricity. In the case of MFC, microbes are used to convert organic substrates (i.e., their fuel) into electricity, resulting in an overall reduction in chemical oxygen demand (COD) in the process. When using various wastewaters as substrates for MFC, two main objectives are met: (1) COD reduction to comply with reuse, recycle, and/or discharge requirements and (2) power production. While most wastewater treatment approaches require an energy input, MFC have the potential to be a net zero energy system (i.e., the power produced is the same as the power required for operation).

Several different substrates have been studied for use in MFC, with significant work carried out on synthetic matrices. The main criteria for substrate selection are the availability of sufficient COD levels and the ability to sustain growth of "anode-reducing bacteria" (i.e., bacteria that can form a biofilm on the MFC anode and produce electricity).  While overall total COD is important, the real challenge is for the organic compounds in these wastewaters to be easily degraded by the MFC bacteria, which is not always the case. The focus of this study was the evaluation of a number of real wastewater samples from various industries for their usability in MFC. Results of power production, COD removal, and coulombic efficiency indicated that a number of real wastewaters are well-suited for MFC use. In addition, methods for substrate conditioning were devised that resulted in improved MFC performance.