A novel bioelectrochemical technique called microbial fuel cells (MFCs) uses electrons from bacterially catalysed metabolic activities to generate electricity. It is anticipated that the energy produced by MFCs will be sufficient to provide a portion of the energy needs of urban WWTPs. In MFCs, a conductive substance transports the electrons that are liberated by bacteria during substrate oxidation from the anode part of the section (the negative terminal) to the cathode chamber (the positive terminal). Protons diffuse via the proton itself exchange membrane at the cathode, where they mix with oxygen. MFCs need constant anode electron release and cathode electron consumption. The gap between the anode potential and the achievable energy from metabolic processes gain for bacteria.
The best possible configuration for MFC is still being researched, and in order to improve its efficiency, new electrode materials and more precise protons exchange membranes are presently being created. Small cells paired in series appear to have more capacity over larger reactor sizes. At present, the primary obstacles to the widespread use of MFC are the expensive price of raw materials and the inadequate buffering ability of home wastewater. This is the reason why MFC has not yet found industrial use. However, laboratory tests have successfully proven the viability of utilising MFCs to treat domestic wastewater, yielding power densities with roughly 420-460 mW m−2 and COD removal rates of up to 50%. Recently, an MFC fed using artificial waterways able to remove C and N.
In this instance, carbon oxidation and SND were carried out independently in the cathode compartment. This setup minimised the COD requirements while optimising the C source. Furthermore, the MFC technique can function very well at moderate COD/N ratios because denitrification leverages the charged particles obtained from the independent combustion of organic materials present in the effluent. As a result, less external C-source supply is needed. Thus, the findings documented in the literature demonstrate that it is feasible to remove N from MFCs while producing energy, thereby advancing the prospect of self-sufficient WWTPs.