Microbial Electrochemical Technologies for Wastewater Treatment: Principles and Evolution from Microbial Fuel Cells to Bioelectrochemical-Based Constructed Wetlands

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.

A new concept in constructed wetlands: assessment of aerobic electroconductive biofilters

“…Among existing technologies, flooded constructed wetlands (CW) were recently identified as potential hosts for integrating METbased technologies. 22 CW are engineered systems made of a gravel or sand biofilter bed with wetland plants that use the natural functions of vegetation and microorganisms to remove pollutants from wastewater. They have been widely used for decades in urban WWT for small communities 23 and present the advantages of low energy requirements, low costs of operation and maintenance, and good landscape integration in comparison to conventional WWT technologies.…”

Feasibility of Ni/Ti and Ni/ GF cathodes in microbial electrolysis cells for hydrogen production from fermentation effluent: A step toward real application

“…5,6 In a microbial electrolysis cell (MEC) system, the electroactive bacteria (EAB) generate the currents (electrons) and protons from substrate. 2 The EAB such as Shewanella oneidensis, Pseudomona aeroginosa 7 or mixed-culture, consume(s) organic substrates, which produce electrons, protons, and release carbon dioxide (CO 2 ). The electrons are transferred by EAB to the anode material while the protons are released to the anolyte.…”

Exoelectrogenic Anaerobic Granular Sludge for Simultaneous Electricity Generation and Wastewater Treatment

“…The special conductive property between AGS and the electrode may open up many other intriguing applications. For instance, the exoelectrogenic AGS could be used as the bed electrodes in METland (wetland plus MET) and other fluidized bed reactor systems 63 .…”