MICROBIAL FUEL CELL: AN ENERGY HARVESTING TECHNIQUE FOR ENVIRONMENTAL REMEDIATION

Abstract

Pollution of soil and water environments is mainly due to different anthropogenic factors, and the presence of organic contaminants, in particular persistent, bioaccumulative and toxic ones, arouses concern for their possible effects on environment and human health. One nature-based technology that can be used in biodegradation of contaminated soil and water is microbial fuel cells (MFCs). They are also capable of producing energy and of being used as environmental sensors. In this context, this article aims at presenting the capacity of MFCs to reduce environmental pollution by exploiting the process of bioelectrochemical utilization of organic matter via microbial metabolism, to generate usable byproducts, fuels and bioelectricity. The main characteristic of an MFC, when used for energy harvesting, is the absence of emissions of pollutant gases such as CO, CO2, SOx or NOx. This characteristic, together with the intrinsic capacity of bioreactors to decontaminate soils and water, is stimulating the research into engineering solutions exploiting the MFC potential. Among the different types of MFCs, as bioelectrochemical systems (BESs), the terrestrial microbial fuel cells and the wastewater microbial fuel cells convert energy using a biocatalyst (microorganism) and a biofuel (organic substrate) in basic environments such as soil and water. Consequently, MFCs can be used as energy sources for powering sensors with low-power and low-voltage characteristics or complete single nodes of a distributed wireless sensor network, if coupled with smart although more complex electronic circuit. Moreover, MFCs can be environmental sensors, suited to monitoring some environmental parameters influencing MFC functional behaviours such as pH and temperature. This article introduces the polluted environment scenarios where these technologies could be suitably applied together with the description of two main types of MFC structures and their functioning. Furthermore, some case studies in which MFCs are used in decontamination of polluted environments are described.