Effect of Thermal Pre-Treatments Method on Sludge Degradation Process Prior Usage in Membrane-Less Microbial Fuel Cell for Electricity Generation

Abstract

Microbial Fuel Cell (MFC) is gaining high interest by researcher around the globe as this is a promising renewable technology that has capability in producing electrical energy. In this study, the effect of the thermal pretreatment method (60, 80, 100, 120 and 140°C) on dewatered sludge (DS) as substrate for electrogenic bacteria (EB) in ML-MFC was optimized using one-factor-at-a-time (OFAT) method. The treated sludge then was used in ML-MFC by exposing them to the constant incubation temperature (35°C) with constant parameter of pH (6), initial moisture content (30 % vol/wt) and electrodes distance (3 cm) for 7 days incubation period. The performance of ML-MFC was relied on generation of soluble chemical oxygen demand (SCOD), power generation and EB biomass. Results shows the thermal pretreatment at 80°C was the optimum condition as the DS degradation rate (increment 78 %) when DS was treated for 4 h time treatment prior used in the ML-MFC. The degradation of DS was further degraded in ML-MFC via bio-catalysis process (51 % of SCOD produced compared initial DS inserted in MFCs ∼ 66 % SCOD removal). It was important to have a high DS degradation as the EB in ML-MFC would obtain more ‘food’ to growth thus increased the voltage (239 mV) and power density (98.34 mW/m 2) generation. In comparison, the control ML-MFC recorded low performance of DS degradation rate (21 %), voltage (24 mV) and power density 0.88 mW/m 2. Thus, by combining the pretreatment method of dewatered sludge prior used in ML-MFC it could improve the performance and expanding the application of ML-MFC as future renewable technology for sustainability of power sources. The EB strains was Bacillus subtilis sp.