Abstract

Humankind has always been engaged in a relentless quest for energy to drive daily activities. However, most of the existing conventional strategies of tapping the environment are expensive and polluting. A nascent microbial fuel cell technology, relying on the degradation of wastewater such as cheese whey with the subsequent release of electricity, is thus the focus for sustainable energy. It is therefore important to gain an in-depth knowledge of the biology in these devices and possible avenues of enhancing power generated from them.  In an effort to increase power from whey-driven microbial fuel cells (MFCs), graphite sheet anodes were incubated in whey for two months then reused in four cycles of seven days each in MFCs. The concomitant remediation was additionally determined. Highest power density (390 ± 21 W/m²) was obtained during the third reuse cycle with a coulombic efficiency of 0.25%. The highest tCOD removal (44.6%) was however, noted during the second cycle. The performance of reactors depended on the number of reuse cycles with the third cycle proving to be the best after which there was a decline in power density. In addition, molecular analyses of anodophilic microorganisms showed the presence of three species related to strains from Lactobacillus helveticus(85% identity), Proteus mirabilis (96%) and Escherichia coli (96%). Therefore the necessity of biofilm build up should take into account the limitation of maximum number of reuse cycles where the flora will be performing at its best.

Key words: Cheese whey, green power, microbial fuel cell, biofilm, bioremediation.