Development and Commercialization of Granular Activated Carbon Microbial Fuel Cells for Wastewater Treatment and Power Generation

Wastewater treatment facilities serve a critically important environmental and public health function, but do so at a very high cost. Implementation of microbial fuel cell (MFC) technology in wastewater systems could change the fundamental energy budget of treatment nationwide. The Phase I SBIR project, entitled "Electricity Generation from Anaerobic Wastewater Treatment in Microbial Fuel Cells (MFCs)," successfully demonstrated that MFCs can treat municipal wastewater and generate electricity simultaneously. In this pilot-scale project, which had considerable outside funding, a multi-anode/cathode granular activated carbon-based MFC (MAC-GACMFC) was designed, constructed, operated, and modified to treat municipal wastewater at temperatures of 25 to 30°C with a hydraulic retention time of 20 hours and external resistances of 100 ohm. Electrical power was produced, and effluent chemical oxygen demands (CODs) less than 50 mg/L were achieved in continuous-flow anaerobic MAC-GACMFC systems treating primary effluent. In the proposed Phase II scope of work, two major tasks will be conducted to optimize MFC operation and improve power generation for future commercialization. In the first task, the MAC-GACMFC capabilities will continue to be tested at alternate operating conditions in order to develop a rational basis for design. Specifically, the first task will: Determine treatment performance with primary effluent as the substrate; Examine performance with higher strength dairy-based wastewaters; Determine performance impacts at lower temperatures; Investigate performance at alternate hydraulic retention time (HRT) levels; and Examine the impact of alternate external resistance levels. In the second task, the MFC system configurations and materials will be modified and developed with the objectives of improving power generation and treatment efficiency and developing a practical, cost-effective commercial product. The design improvements will be critical to commercializing the technology. Specifically, the second task will address: Improvements to anode/cathode pairs to minimize internal resistance and improve access for maintenance and repair; Optimizing anode to cathode ratios and anode density in the GAC bed; and Testing alternate (lower cost) catalyst coatings on the cathode material to replace the costly platinum coating. Lab-scale tests have shown encouraging results with alternative catalysts. The anticipated results of Phase II will be used to develop a greatly improved and engineered MFC system for future commercialization. In the opinion of the Project Team, this unique MFC technology has great potential to be developed as a modularized system, enhancing its feasibility as a cost-effective, practical retrofit for municipal wastewater treatment systems.