Enzyme-Enhanced Microbial Fuel Cells
University of Delaware
Microbial fuel cells utilize the electrons released during the oxidation of organic material by microbes to generate electricity. The electrons may be transferred to an electrode surface by redox mediators or directly by the microbes residing in the fuel source. Wastewater sludge was the source of organic material for the reactors operated during this project. Two phases of experiments were conducted to determine conditions for efficiently operating microbial fuel cells powered by waste biosolids. The first phase focused on finding a combination of supplemental nutrients and enzyme to sustain a useable electric current within the fuel cells. The second phase focused on identifying an enzyme solution dose to enhance fuel cell performance. In Phase I, after applying a variety of supplemental nutrient solutions to the reactors, it appeared that tryptic soy broth provides a sufficient balance of carbon, nitrogen, and phosphorus to sustain microbial growth. The reactors which received a supplemental nutrient source had more consistent rates of electrical output than the reactor that received only the enzyme treatment. In Phase II, it was shown that the enzyme treatment enhances fuel cell performance. The optimal dose appears to be between 20 and 40 mg daily of EZ 216, which is a commercial mixture of enzymes. The results of both sets of experiments support the hypothesis that microbial fuel cells can be operated efficiently with waste biosolids. In a batch system, the supplemental nutrient source is necessary to sustain microbial growth, which can be further enhanced by the addition of an enzyme.
microbial fuel cells , enzyme treatment