How Comparable are Microbial Electrochemical Systems around the Globe? An Electrochemical and Microbiological Cross‐Laboratory Study

Abstract

In memory of Dr. Alessandra ColomboA cross-laboratory study on microbial fuel cells (MFC) which involved different institutions around the world is presented. The study aims to assess the development of autochthone microbial pools enriched from domestic wastewater, cultivated in identical single-chamber MFCs, operated in the same way, thereby approaching the idea of developing common standards for MFCs. The MFCs are inoculated with domestic wastewater in different geographic locations. The acclimation stage and, consequently, the startup time are longer or shorter depending on the inoculum, but all MFCs reach similar maximum power outputs (55 � 22 μW cm À 2 ) and COD removal efficiencies (87 � 9 %), despite the diversity of the bacterial communities. It is inferred that the MFC performance starts when the syntrophic interaction of fermentative and electrogenic bacteria stabilizes under anaerobic conditions at the anode. The generated power is mostly limited by electrolytic conductivity, electrode overpotentials, and an unbalanced external resistance. The enriched microbial consortia, although composed of different bacterial groups, share similar functions both on the anode and the cathode of the different MFCs, resulting in similar electrochemical output.

Microbe–Anode Interactions: Comparing the impact of genetic and material engineering approaches to improve the performance of microbial electrochemical systems (MES)

“…Concerning electroactive bacteria, researchers have mainly focused on model organisms such as Shewanella and Geobacter species to understand the fundamentals of EET, and therefore the comparison in this review naturally focuses on these model organisms. However, Light et al ( 2018 ), Santoro et al ( 2021 ) as well as Edel, Philipp, Lapp, Reiner, and Gescher ( 2022 ) have shown that there is an enormous number of organisms that perform EET based on flavins or c ‐type cytochromes that have not been considered in BES applications yet. The diversity of these unknown metabolic pathways and microorganisms could be the foundation for advanced BES applications.…”

Electric discharge by sulphide shuttling bacteria

“…27 However, many of the occurring species have been detected in electrochemically active biofilms or planktonic cultures, such as Thioalkalivibrio sulfidophilus, Acholeplasma sp. and Bacteroidales GZKB119 15,20,[28][29][30] (Table 3).…”

Electro-fermentation: Sustainable bioproductions steered by electricity

“…At larger scales (L or m 3 scale), selecting proper mixing conditions is required to increase the contact time between the biofilm and fresh medium, in addition to avoiding pH gradients (Zeppilli et al, 2021). Information available in the literature about design parameters of bioelectrochemical reactors is scarce and lacks standardization of data representation (Santoro et al, 2021). For example, dimension-less numbers (e.g., Reynolds or Newton numbers) or chemical oxygen demand as the total carbon equivalent for the coulombic efficiency calculation must be given to allow proper benchmarking (Krieg et al, 2018a).…”