Innovative microbial fuel cell design for investigation of cathode chamber effect and electricity generation enhancement

Abstract

In this study, a novel laboratory design of microbial fuel cell (MFC) was composed of one central anode chamber integrated with four surrounding cathode chambers and uncoated graphite was employed as anode and cathode electrodes to study the cathodic effective operation factors and to investigate the enhancement of MFC performance by using ozone gas. Cathodic operation factors that had been focused on studying their impact, including the cathode electrode surface area (156-936 cm2) and the cathode electrode distance from the anode chamber (3-9 cm), the catholyte salt types are sodium sulfate Na2SO4, potassium chloride KCl, and sodium chloride NaCl at 50 mM for each, and concentration of salt (2.5-35 NaCl g/L) used in the catholyte. It was observed that the increase in the cathode electrode surface area had a significant effect to increase power generation, while the increase in electrode distance had an opposite impact. The influence of the catholyte type depends on the extent of the electrical conductivity to produce higher electrical power. Meanwhile, the increase in catholyte salt concentration inhibited the MFC performance due to decrease the dissolved oxygen concentration, especially under oxygen saturated concentration. The higher electrical power production was 23.051 mW/m2 at 936 cm2 surface area and NaCl concentration 15 g/L. Also, the MFC performance was improved by using dissolved ozone as an electron acceptor in reduction reaction and increased the power generated about 15 times higher than electricity generated by using dissolved oxygen. This work demonstrated that the conditions of cathodic reduction reaction play important rule along with the anodic oxidation reaction conditions on electrical power generation in MFC.