Chemical Oxygen Demand Sensor Based on Microbial Fuel Cell Using Low-Cost Electrodes Fabricated from Waste Rice Husks

Abstract

Environmental pollution is one of the problems that humankind must solve for a sustainable future. Monitoring of Chemical Oxygen Demand (COD) is an important indicator for monitoring the status of organic pollution in water. However, conventional methods for monitoring COD face high costs and complicated design issues. In this study, the use of microbial fuel cells (MFC) composed of low-cost and easy-to-fabricate electrodes using smoked charcoal from rice husks and Japanese ink was investigated for use in COD sensors. Rice husks are an industrial waste product. Therefore, they can be used at a low cost, and using them can help solve the waste problem, which is one of the causes of environmental pollution. With these materials, the electrodes were fabricated for the cost of $0.022/cm3. In addition, floating MFC was used for the sake of sensing COD in rivers, waterways, and lakes. The high physical stability of the block-shaped electrode used in this study allowed a biofilm to form on the anode surface by inserting the anode into the soil. The block-shaped electrodes were physically stable in solution. The results showed that there was a correlation between COD concentration (30~150 mg/L) and MFC voltage for more than four months. Block-shaped electrodes fabricated with rice husk smoked charcoal and Japanese ink would be a promising electrode for MFC to monitor COD in solution in real-time.