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Linking internal resistance with design and operation decisions in microbial electrolysis cells

Miller, Andrew, Singh, Lakhveer, Wang, Luguang, Liu, Hong
Environment international 2019 v.126 pp. 611-618
anodes, carbon, cathodes, microbial electrolysis cells, prediction, surface area
The distribution of internal resistance in most microbial electrolysis cells (MECs) remains unclear, which hinders the optimization and scaling up of the technology. In this study, a method for quantifying the effects of design and operation decisions on internal resistance was applied for the first time to MECs. In typical single chamber MECs with carbon cloth electrodes, the internal resistance was distributed as follows: 210 Ω cm² for anode, 77 Ω cm² for cathode, and 11 Ω cm² M for solution. While varying the spacing of the electrodes (<1 cm) had little effect on MEC performance, inducing fluid motion between the electrodes decreased the internal resistance of all MEC components: 150 Ω cm² for anode, 47 Ω cm² for cathode, and 5.3 Ω cm² M for solution. Adjusting the anode to cathode surface area ratio, to balance the internal resistance distribution, resulted in a significant improvement in performance (47 A/m² current density, 3.7 L-H₂/L-liquid volume/day). These results suggest that the quantification of the internal resistance distribution enables the efficient design and operation of MECs. The parameters obtained in this study were also capable of predicting the performance of MECs from some previous studies, demonstrating the effectiveness of this method.