Characterization of electricity production and microbial community of food waste-fed microbial fuel cells

Abstract

Food waste (FW) contributes to a great proportion in the municipal solid waste and is generated during disposal from different life cycles of food processing and consumption. FW treatment is a big challenge and there is an urgent need to develop a suitable treatment technology. The microbial fuel cell (MFC) is a promising bioelectrochemical technology using bacteria as the catalyst, which has been developed to effectively generate bioelectricity from diverse organic wastes. The present study investigated the treatment of food waste collected from a Chinese canteen using MFCs under different conditions. It was observed that the highest closed circuit voltage and maximum power density obtained were 775 ± 21 mV and 422 mW m−2, respectively, when using food waste with nutrient medium as the anolyte and permanganate as the catholyte. Under this condition, biodegradation processes in the MFCs could achieve 69 ± 18% COD, 88 ± 5% carbohydrate, 76 ± 9% protein, 65 ± 8% TOC and 71 ± 8% total nitrogen removal. Microbial community analysis using 16S rRNA gene high-throughput sequencing showed Firmicutes, Bacteroidetes and Proteobacteria were the dominant phyla and Geobacter was the most abundant genus. Therefore, our microbial community results suggested that the mixture of exoelectrogenic and fermentative bacteria have a pronounced effect on MFCs system treating FW while affecting on organic degradation and energy production. A power management system was used to demonstrate that electricity from FW-fed MFCs can be successfully harvested to provide intermittent electricity to loads. Overall, this study demonstrated the potential of using MFCs for food waste treatment to achieve electricity production and waste reduction.