A directional electrode separator improves anodic biofilm current density in a well-mixed single-chamber bioelectrochemical system

In this study, a directional electrode separator (DES) was designed and incorporated into a single-chamber bioelectrochemical system (BES) to reduce migration and reoxidation of hydrogen. This issue arises when H₂, generated at the cathode, travels to the anode where anodic biofilms use H₂. To test the feasibility of our design, a 3D-printed BES reactor equipped with a DES was inoculated with anaerobic digestor granules and operated under fed-batch conditions using fermented corn stover effluent. The DES equipped reactor achieved significantly higher current densities (∼53 A/m²) compared to a conventional single-chamber BES without a separator (∼16 A/m²), showing a 3.3 times improvement. Control abiotic electrochemical experiments revealed that the DES exhibited significantly higher proton conductivity (456±127 µS/mm) compared to a proton exchange membrane (67±21 µS/mm) with a statistical significance of P=0.03. The DES also effectively reduced H₂ migration to the anode by 21-fold relative to the control. Overall, incorporating a DES in a single-chamber BES enhanced anodic current density by reducing H₂ migration to the anode.