Abstract
Microbial electrochemical technologies (MET) rely on the presence of the metabolic activity of electroactive bacteria for the use of solid-state electrodes for oxidizing different kinds of compound that can lead to the synthesis of chemicals, bioremediation of polluted matrices, the treatment of contaminants of interest, as well as the recovery of energy. Keeping these possibilities in mind, there has been growing interest in the use of electrochemical technologies for wastewater treatment, if possible with simultaneous power generation, since the beginning of the present century. In the last few years, there has been growing interest in exploring the possibility of merging MET with constructed wetlands offering a new option of an intensified wetland system that could maintain a high performance with a lower footprint. Based on that interest, this paper explains the general principles of MET, and the different known extracellular electron transfer mechanisms ruling the interaction between electroactive bacteria and potential solid-state electron acceptors. It also looks at the adoption of those principles for the development of MET set-ups for simultaneous wastewater treatment and power generation, and the challenges that the technology faces. Ultimately, the most recent developments in setups that merge MET with constructed wetlands are presented and discussed.
Highlights
Bioelectrochemistry is the merging field between microbiology and electrochemistry, which includes the research interests of environmental engineering, electrochemistry, biochemistry and physics
The results suggest that subsurface snorkels could be a sustainable approach for redirecting the microbial respiration in subsurface environments, and profile such systems as a potential alternative for degradation of organic contaminants and inhibition of methanogenesis in that type of environments [92]
Among the alternative Microbial electrochemical technologies (MET) configurations, CW–microbial fuel cells (MFC) is one of the most innovative setups, which merges the groundbreaking approach of MFC, and the well-known capabilities of constructed wetlands for wastewater treatment
Summary
Bioelectrochemistry is the merging field between microbiology and electrochemistry, which includes the research interests of environmental engineering, electrochemistry, biochemistry and physics. In Faraday interactions, and reduction water and ions from the electrode, resulting in a change of theoxidation electrochemical capacity reactions occur mediated by microbial cells and molecular species involved in extracellular which leads to the flow of electric current. This could be done either by pseudo-capacitive processes and biofilm get charged or reactions mediated by microbial cells and molecular species(cells involved in extracellular electron uncharged, as a supercapacitor) or by a microbial electrocatalysis process, where the electrochemical transfer. In primary MET, the microbial electrochemical processes (exclusively Faraday processes) either involve extracellular electron transfer (EET) mechanisms directly from cell to acceptor or mediated by electron shuttles. It is an interspecies electron transfer that enables a diversity of microbial Water 2018, 10, x FOR communities to gain energy from reactions that no microbe can catalyze [37] It is a mechanism for exchanging electrons during syntrophic metabolism.
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