Advancements in microbial fuel cell technology

Abstract

Crude oil and coal reserves remaining nearly fifty times and one hundred thirty times of current yearly consumption, respectively, the world economy is trying to shift to a more renewable energy-dependent model. Global renewable energy production increased by nearly 60% from 2011 to 2020. Among the renewable energy sources bioenergy provide a prominent portion. Bioenergy can be in form of biogas, liquid biofuels, solid biofuel, etc. However, direct production of electricity by means of biochemical reactions can be done with microbial fuel cells (MFCs). This is an eco-friendly way to produce energy while treating wastewater. In MFCs one anode and one cathode separated by a proton exchange membrane (PEM) are present. Microorganisms present inside the anode chamber produce electron (e-) and proton (H+) after oxidation of organic matters present in wastewater. These electrons are transferred to the cathode chamber through an external connection while the protons pass through a semipermeable membrane called proton exchange membrane (PEM). These electrons and protons react inside the cathode chamber in presence of oxygen to form water. The electron is transferred to the anode from microbes directly through pili/nanowire, a conductive appendage of microbe, or by indirect mechanism using career compounds like pyocyanine, thionin. MFCs can be many types depending on the presence of membrane, presence of liquid in cathode chamber, number of chambers, number of electrodes, type of PEM, the direction of flow, electrode material, etc. MFCs are successfully tested to treat domestic wastewater as well as wastewater from different industries like brewery, paper and pulp, pharmaceutical, food processing. Other than a standalone MFC system this technology is applied as a hybrid system with anaerobic-anoxic-oxic (AO/O) treatment, membrane bioreactor treatment, constructed wetland treatment, etc. This technology is also used as toxicity sensor as well as BOD sensor. In recent years, many researchers are working on improving the scalability of MFC technology. Production of electricity using MFC from human excreta and urine while acting as a treatment facility has also grabbed the attention of many in recent years. However, until economic sustainability is fully achieved for large-scale MFCs mass scale adoption of this technology cannot be attained. � The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.