Bioelectricity generation from chemical wastewater treatment in mediatorless (anode) microbial fuel cell (MFC) using selectively enriched hydrogen producing mixed culture under acidophilic microenvironment

Bioelectricity generation from composite chemical wastewater treatment was evaluated in a dual chambered microbial fuel cell (MFC) [anode chamber (mediatorless; perforated plain graphite electrode); cathode chamber (50 mM potassium ferricyanide [K3Fe(CN)6] in phosphate buffer; pH 7.5; plain graphite electrode)] inoculated with selectively enriched hydrogen (H2) producing mixed culture under acidophilic microenvironment (pH 5.5). Anode chamber, which resembles anaerobic suspended contact reactor was fed with wastewater and operated in absence of artificial mediator at acidic environment to proliferate H2 producing bacteria. Experimental data showed the feasibility of producing bioelectricity from wastewater treatment, though power production was found to be dependent on the substrate loading rate. Maximum voltage of 271.5 mV (5.43 mA) and 304 mV (6.08 mA) was recorded at operating organic loading rates (OLR) of 1.165 kg COD/(m3 day) and 1.404 kg COD/(m3 day), respectively when measured at 50 Ω external resistors at stable operating conditions. COD removal efficiency of 35.4% (substrate degradation rate (SDR) of 0.412 kg COD/(m3 day)) and 62.9% (SDR, 0.88 kg COD/(m3 day)) was observed at OLRs 1.165 kg COD/(m3 day) and 1.404 kg COD/(m3 day), respectively. Maximum specific power production of 0.163 W/kg CODR (1.165 kg COD/(m3 day); 50 Ω) and 0.198 W/kg CODR (1.404 kg COD/(m3 day); 100 Ω) was observed during stable phase of fuel cell operation. Current density of 747.96 mA/m2 (1.165 kg COD/(m3 day)) and 862.85 mA/m2 (1.404 kg COD/(m3 day)) was documented at 10 Ω. Utilizing chemical wastewater for the production of renewable energy (bioelectricity) from anaerobic treatment is considered as a feasible, economical and sustainable process.