Evaluation of electrode materials and external resistance in microbial fuel cells to improve wastewater treatment and bioenergy production

Abstract

Dual chamber microbial fuel cells (DC-MFCs) are a technological alternative that can be applied to both wastewater treatment and bioenergy generation. This research evaluated the influence of new carbon-based electrode materials, catholytes, and external resistances on the performance of a DC-MFC. The evaluations were carried out using graphite, graphene and hydrophilic-treated graphene (HTG) electrodes in a DC-MFC. Additionally, different external resistance of 10 Ω, 100 Ω, 1 kΩ, and 2.2 kΩ were also evaluated. For the entire evaluation, a 0.1 M hydrochloric acid (HCl) solution and deionized water were used in the cathodic chamber. Domestic wastewater served as a substrate, and a DuPont TM Nafion 117 membrane acted as the proton exchange membrane. The results showed that HTG has a large superficial area and high conductive properties compared to graphene and graphite. The findings are in agreement with the maximum power density obtained, which was 32.07 mW·m−2 using HTG electrodes, HCl as catholyte, and an external resistances of 100 Ω. In addition, an assessment of external resistances of 10 Ω, 100 Ω, 1,000 Ω, 2,200 Ω in a DC-MFC revealed the effect these resistance exert on anodic potential, the development of microbial communities, overpotential losses, and COD removal. These results indicated that the use of a 100 Ω external resistance, HTG electrodes and HCl as catholyte was the conditions that best favored energy production by treating 3.4 L of domestic wastewater in DC-MFC. Based on these results, it is highly recommended to continue investigating large-scale MFCs for their feasible application.