Microbial bioanodes with high salinity tolerance for microbial fuel cells and microbial electrolysis cells

•Microbial bioanodes were formed on carbon felt under constant applied potential.•Acetate was supplemented to avoid any significant current decrease.•Sediments from salt marsh were used as inoculum.•Current densities up to 85 A·m− 2 were reached.•The bioanodes operated in 45 g·L NaCl solution (1.5 times seawater salinity).

Increasing the conductivity of the electrolytes used in microbial electrochemical systems is an essential prerequisite to the large-scale success of these technologies. Microbial bioanodes formed from a salt marsh inoculum under constant acetate feeding generated up to 85 A·m− 2 in media containing 776 mM NaCl (45 g·L− 1, 1.5 times the salinity of seawater). These values were the highest salinities accepted by a microbial anode so far and the highest current densities reported with felt graphite electrodes.