Evaluating Microplastic Effects on Performance and Electrochemistry of Microbial Fuel Cells for Wastewater Treatment

Abstract

Microplastics (MPs) that are contained in water pose a great threat to the ecological environment, because they have the potential to biomagnify in the food chain, which negatively affects higher trophic level animals that include humans. In addition, they could adsorb several contaminants onto their surface due to their high adsorption capability, which poses a great risk of diseases in higher life forms. Microbial fuel cells (MFCs) can simultaneously treat MP-containing wastewater and produce value-added by-products in the form of bioelectricity; therefore, recent research is more focused on this area. This work explored the effect of MPs on chemical oxygen demand (COD) reduction, power production, and an electrochemical behavior study of the system with cyclic voltammetry (CV). The results of this work show that MPs in low concentrations (25–400 mg/L) in synthetic wastewater treatment had a more positive effect on COD reduction and power production than synthetic wastewater with no MPs and 1,000 mg/L MP. The mitigation of microplastic (MP)-containing wastewater has become very essential in today’s world. Apart from leading to water pollution, it poses significant environmental risks, such as ecosystem disruption and habitat degradation, by the accumulation of MPs in aquatic habitats, which bioaccumulate and enter the food chain. Then, they are ingested by smaller organisms and are passed onto larger ones, which adversely affects marine life. Contamination via MPs is not limited to marine ecosystems but is transferred to terrestrial ecosystems and harms terrestrial organisms, because MPs can absorb and concentrate other pollutants, such as pesticides and heavy metals, from neighboring environments. Therefore, in this work, a newer green approach has been taken to treat MP-containing wastewater and to evaluate its effect on the performance and electrochemistry of microbial fuel cells (MFCs). The results of this work show that among the cycles, Cycle 5 with 400 mg/L MP gave the highest power density of 1,971.86 mW/m2, which makes it an energy-yielding process. The chemical oxygen demand (COD) removal efficiency of Cycle 2 (50 mg/L MP) was highest at 47 ± 0.5; however, Cycle 5 (400 mg/L MP) could reduce 33.3% ± 0.5% of the COD.