Correlation of the Electrochemical Kinetics of High-Salinity-Tolerant Bioanodes with the Structure and Microbial Composition of the Biofilm

Abstract

Increasing the conductivity of the electrolytes used in microbial electrochemical systems is an essential prerequisite to large‐scale application of these technologies. Microbial anodes formed on carbon felt from a salt marsh inoculum under polarisation at 0.1 V (versus a saturated calomel electrode), generated up to 85 A m−2 in media that contained 30–45 g L−1 of NaCl. Analyses of microbial populations showed a stringent selection of the two microbial genera Marinobacter and Desulfuromonas. Currents decreased if NaCl concentration was increased to 60 g L−1. This highest salinity was shown to consistently impact the bioanode performance in three ways: voltammetry indicated degraded electron‐transfer kinetics, confocal laser scanning microscopy showed a modified biofilm structure and DNA pyrosequencing detected a decrease in the level of Desulfuromonas spp. relative to Marinobacter spp. A consistent correlation was, thus, found between electrochemical kinetics, biofilm structure and the composition of the microbial community.