Investigation of electrode combinations in electricity generation from the pulp and paper industry wastewater

Bioelectrochemical systems are a new secondary effluent treatment method where bacteria degrade industrial sludge and generate electricity for the external circuit. In this study, paper industry wastewater effluents were treated in microbial fuel cells (MFCs) by utilising six different sets of electrodes to produce bioelectricity. Bacterial biofilms were studied by field emission scanning electron microscopy (FESEM). Investigation disclosed that zinc mesh and carbon plate (MFC-2) had the highest power generation as observed with 1193 mV of output voltage, 2.69 mA output current and 533 mW/m2 power density along with 92% BOD removal without electrolyte solution. The lowest 325 mV of output voltage, 0.15 mA of output current and 7.0 mW/m2 of power density with 37% removal of BOD were measured for MFC-3, which was constructed with Al mesh and carbon plate. A total of 1.0 M CuSO4.5H2O cathodic electrolyte solution was added in MFC-5 with zinc and copper plates as electrodes, which enhanced the power generation and BOD removal. The highest output voltage, current and power density were obtained for MFC-5 with the magnitude of 1185 mV, 4.79 mA and 939 mW/m2, respectively.