Developing and Optimization of Fragmented Electroactive Biofilm Reactor (FAB) to Increase Microbial Fuel Cell Bioelectricity Generation and Treatment Performance

Abstract BackgroundMicrobial fuel cells (MFCs) drawbacks are anode (cathode) limitation and electrochemical loss. Engineering the biofilm for enhanced attachment to the electrode is the prospect of MFC. Recent studies, recommend the formation of thick anode biofilm that could result in a synergetic effect between microbial communities. To address these issues, a microbial electrode jacket dish (MEJ-dish) was invented that supports microbial growth over the anode electrode surface. The MFC reactor with MEJ-dish was hypothesized to develop a fragment of biofilm (thick and thin) across the electrode. This reactor is called a fragmented electroactive biofilm-microbial fuel cell reactor (FAB-MFC).ResultsThe maximum voltage generated (0.87 V) was recorded in FAB-MFC. In addition, during the first 3-10 days, the FAB system enables to significantly (p<0.05) maximize the voltage generation at pH variation from 6.5 to 7.5. However, at alkaline pH 8.5, the FAB system generates a lower voltage relative to non-FAB. On the contrary, in FAB reactors the COD removal was improved regardless of pH variation (6.5-8.5). This shows, unlike voltage generation, the biofilms (either electroactive or not) formation were vital for COD removal even without voltage generation. At acidic and neutral pH (7.5), the fragmented (hybrid) biofilm formation across the bioelectrode (anode) could not only important for voltage generation but also contributes to the effective functioning of electroactive biofilm (EABs) growth and development by reducing the effect of pH variation. To address this contradictory effect of increasing COD removal associated with the lower voltage at higher pH, might be to use both FAB and non-FAB in a single MFC reactor. There might be a mutualistic effect across the bioelectrode biofilms.ConclusionsThis study showed that the voltage generated was significantly higher in FAB-MFC as compared with non-FAB-MFC setup within limited pH (6.5-7.5); relatively, COD removal was enhanced within wider pH 6.5-8.5. This supports the conclusion that biofilm formed across the FAB was vital for COD removal, even though not participated in voltage generation. However, this might be affected by the degradable organic content and the nature of the microbial community in the inoculum and domestic wastewater, which requires further studies.