Application of clayware ceramic separator modified with silica in microbial fuel cell for bioelectricity generation during rice mill wastewater treatment

Abstract

Ceramic separators have recently been investigated as low-cost, robust, and sustainable separators for application in microbial fuel cells (MFC). In the present study, an attempt was made to develop a low-cost MFC employing a clayware ceramic separator modified with silica. The properties of separators with varying silica content (10%–40% w/w) were evaluated in terms of oxygen and proton diffusion. The membrane containing 30% silica exhibited improved performance compared to the unmodified membrane. Two identical MFCs, fabricated using ceramic separators with 30% silica content (MFCS-30) and without silica (MFCC), were operated at hydraulic retention time of 12 h with real rice mill wastewater with a chemical oxygen demand (COD) of 3,200 ± 50 mg/L. The maximum volumetric power density of 791.72 mW/m3 and coulombic efficiency of 35.77% was obtained in MFCS-30, which was 60.4% and 48.5%, respectively, higher than that of MFCC. The maximum COD and phenol removal efficiency of 76.2% and 58.2%, respectively, were obtained in MFCS-30. MFC fabricated with modified ceramic separator demonstrated higher power generation and pollutant removal. The presence of hygroscopic silica in the ceramic separator improved its performance in terms of hydration properties and proton transport. Highlights Ceramic separator modified with silica (30% w/w) outperformed unmodified separator.; 1.5 times more proton mass transfer was observed in ceramic separator with 30% silica.; Internal resistance of the MFC decreased 1.6 times due to better proton mobility.; Volumetric power density of 0.8 W/m3 and COD removal of 76.24% was achieved.; 1.5 times higher coulombic efficiency was obtained in the MFC operated with modified separator.;

Keywords

• ceramic separator
• coulombic efficiency
• microbial fuel cell
• power density
• rice mill wastewater treatment
• silica modification