Biohydrogen production from potato processing wastewater using double-chamber microbial electrolysis cell with Ru and Pd coated graphite cathodes

Microbial electrolysis cells (MECs) are promising for biohydrogen production from waste streams, yet their overall energy efficiency requires enhancement to be viable. This study, for the first time, utilized doublechamber MECs with graphite (Gr), ruthenium-coated graphite (Ru), and palladium-coated graphite (Pd) cathodes for biohydrogen production from potato processing wastewater under various applied voltages. The highest hydrogen evolution rate (HER) and energy efficiency (eta e) were achieved in the Ru reactor at 1.0 V, reaching 0.43 LH2 L- 1d- 1 and 106 %, respectively. These represent improvements of 81 % in HER and 33 % in eta e compared to the uncoated Gr reactor. The surface morphology of the Ru and Pd coated electrodes was characterized by SEM and XRD. Next-generation sequencing of the anode biofilm indicated a microbial community comprising polysaccharide-consuming bacteria, such as the phylum Bacteroidetes, and key exoelectrogens, including the genus Geobacter. An Artificial Neural Network (ANN) model (R2 = 0.9432) was also developed to simulate HER performance, confirming high performance of Ru-coated cathode under various voltages. A techno-economic analysis (TEA) was conducted to assess the effect of cathode coating on the payback period. The analysis revealed that Pd and Ru coatings reduced the payback period by approximately 36 % and 34 %, respectively.