Testing various food-industry wastes for electricity production in microbial fuel cell.

Three food-industry wastes: fermented apple juice (FAJ), wine lees and yogurt waste (YW) were evaluated in combination with two sources of inoculum, anaerobic sludge and garden compost, to produce electricity in microbial fuel cells. Preliminary potentiostatic studies suggested that YW was the best candidate, able to provide up to 250 mA/m(2) at poised potential +0.3V/SCE. Experiments conducted with two-chamber MFCs confirmed that wine lees were definitely not suitable. FAJ was not able to start an MFC by means of its endogenous microflora, while YW was. Both FAJ and YW were suitable fuels when anaerobic sludge or compost leachate was used as inoculum source. Sludge-MFCs had better performance using YW (54 mW/m(2) at 232 mA/m(2)). In contrast, compost-leachate MFCs showed higher power density with FAJ (78 mW/m(2) at 209 mA/m(2)) than with YW (37 mW/m(2) at 144 mA/m(2)) but YW gave more stable production. Under optimized operating conditions, compost-leachate MFCs fueled with YW gave up to 92 mW/m(2) at 404 mA/m(2) and 44 mW/m(2) in stable conditions.