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DESIGN OF AN ANAEROBIC DIGESTER AND FUEL CELL SYSTEM FOR ENERGY GENERATION FROM DAIRY WASTE
Impact/Purpose:
The Bio-Environmental Design Team at The Ohio State University (OSU) will collaborate with the Department of Food, Agricultural and Biological Engineering (FABE) Undergraduate Senior Capstone Design Course to design, build, and test a bench scale renewable electrical energy generation system employing a microbiological fuel cell to utilize dairy waste as a feedstock. The OSU Waterman Dairy Farm will provide necessary waste products. This microbiological fuel cell system will be scaled up for pilot testing based on experimental bench results, time, and resources available.
Description:
Dairy waste was found to have a natural population of microorganisms capable of seeding an MFC. Dairy wastewater also proved to be a very effective substrate. Different graphite electrode materials provided varying levels of electrical energy generation, demonstrating with greater than 99.99% confidence (P-value <0.00 1) that electrode material has an impact on the electrical output of MFCs. Porous graphite foam produced the highest energy per surface area (3.21 mW/m2), but was the most expensive electrode material ($1 3/in2). Performance of graphite gasket material and graphite plate was statistically similar and gave the second highest energy per surface area values (1.762 and 1.914 mW/m2, respectively). Graphite gasket, previously unmentioned in MFC literature, was found to he the most inexpensive and abundant alternative ($0.12/in2). The other two electrode materials tested gave the poorest performance with 1.212 mW/m2 from graphite felt fabric and 0.829 mW/m2 from graphite paper. All the MFCs tested reduced biochemical oxygen demand (HOD) by 10.9- 29.6% over a ten day period. On average, the graphite gasket electrode MFCs yielded a 23.6% reduction in BOD. A larger scale design has been constructed and is being tested as a power source for a battery charger. Phase I has lead to several individual undergraduate honors projects and graduate research programs and to the establishment of the Microbial Fuel Cell Laboratory at The Ohio State University.