Canteen based composite food waste as potential anodic fuel for bioelectricity generation in single chambered microbial fuel cell (MFC): Bio-electrochemical evaluation under increasing substrate loading condition

Abstract

Canteen based composite food waste, which is rich in organic constituents was evaluated as anodic fuel (substrate) in single chambered microbial fuel cell (MFC; mediator less; non-catalyzed graphite electrodes; open-air cathode) to harness electrical energy via anaerobic treatment. The performance of MFC was evaluated with anaerobic consortia as anodic biocatalyst under various increasing organic loading rates (OLR1, 1.01 kg COD/m 3-day; OLR2, 1.74 kg COD/m 3-day; OLR3, 2.61 kg COD/m 3-day). The experimental results illustrated the feasibility of bioelectricity generation from food waste along with treatment but depend on the applied organic load. The maximum power output was observed at OLR2 (295 mV; 390 mA/m 2), followed by OLR3 (250 mV; 311 mA/m 2) and OLR1 (188 mV; 211 mA/m 2). The variation in substrate degradation has also showed a relation with organic load applied (OLR1, 44.28% (0.47 kg COD/m 3-day); OLR2, 64.83% (1.13 kg COD/m 3-day); OLR3, 46.28% (1.39 kg COD/m 3-day)). The increase in loading from OLR1 to OLR2, the catalytic ability of biocatalyst increased from 7.5 mA (24 h) to 11.22 mA (24 h) along with the increase in power generation from 39.38 mW/m 2 to 107.89 mW/m 2. At the higher OLR (OLR3), the bioelectrocatalytic current decreased to 5.3 mA (24 h) along with decrement in power to 78.92 mW/m 2. The optimum organic load (OLR2) showed maximal catalytic activity and power output. Fuel cell behavior with respect to polarization, anode potential and bio-electrochemical behavior supported the higher performance of MFC at OLR2. Specific power yield was also observed to be higher at OLR2 (0.320 W/kg COD R) indicating the combined process efficiency. Volatile fatty acids generation and pH profiles also correlated well with the observed results.