Microbial Electrochemical System: A Sustainable Approach for Mitigation of Toxic Dyes and Heavy Metals from Wastewater

Abstract

Anthropogenic activities have lead to the accumulation of toxic and hazardous waste materials, such as dyes and heavy metals, into the environment. The entry of these waste materials into the food chain have emerged as a threat to food and health security. As a result, several conventional physical and chemical-based systems were developed to remove these toxic dyes and heavy metals from wastewater. However, because the conventional methods were costly, energy intensive, and ineffective, microbe-based bioremediation systems gained attention of the scientific community. Among several bioremediations approaches, the microbial electrochemical system (MES) has shown promising results in the selective removal of dyes and heavy metals from wastewater. The chemical energy of the biodegradable substrates is converted to electrical energy using the inherited electrochemical system of the electroactive microorganisms. This is collectively termed a “microbial electrochemical/bioelectrochemical system” (MES/BES). The MES in presence of electroactive microbes can remediate the toxic compounds from a wide range of wastewaters. Thus, the present review provides detailed insight into the principle, mechanisms, electrochemistry, and biochemical capabilities of electroactive microbes during bioremediation of heavy metals and dyes. In addition, the paper discusses the challenges faced in designing large-scale MES and its implementation/commercialization. The future prospect and strategies for the development of a self-sustainable multipurpose MES for bioremediation and recovery of toxic and value-added compounds, respectively, have also been elaborated.