Dual-chamber microbial fuel cells as biosensors for the toxicity detection of benzene, phenol, chromium, and copper in wastewater: Applicability investigation, effect of various catholyte solutions, and life cycle assessment

Abstract

Microbial fuel cells (MFCs) were investigated as biosensors for the toxicity detection of benzene, phenol, chromium, and copper in wastewater as they can instantaneously indicate the presence of these contaminants. In this study, two rectangular MFCs, each composed of anodic and cathodic chambers separated by a proton exchange membrane, were operated in parallel. The anode comprised plain carbon cloth, and the cathode comprised plain carbon cloth covered by 0.5 mg/cm2 20% Pt. The anode chamber was filled with synthetic wastewater containing the designated chemical oxygen demand (COD) concentration, while the cathode chamber was filled with ferricyanide (MFC-F) or aerated tap water (MFC-T). The external resistances varied from 100 − 10,000 Ω, and organic load was assessed at COD values of 500, 750, and 1000 mg/L at a pH of 7. Toxic injections were performed at concentrations of 1, 5, 20, and 100 mg/L. Scanning electron microscope images revealed the formation of biofilm after the start-up period. The results indicate that the contaminants investigated caused an inhibitory effect when present at high concentrations. The inhibition ratios of benzene, phenol, chromium, and copper reached 2.9%, 5.1%, 41.8%, and 13.3%, respectively, for MFC-F. For MFC-T, the inhibition ratios of benzene, phenol, chromium, and copper were 14.3%, 10%, 10%, and 4.7%, respectively. MFC-T was more sensitive to the toxicity of organic compounds, while MFC-F was found to be more sensitive to heavy metal toxicity. A life cycle assessment was also conducted to determine the environmental impacts associated with the two biosensors.