PNNL

Abstract

In this study a directional electrode separator (DES) was used in a single-chamber bioelectrochemical system (BES) to reduce hydrogen (H2) migration and thus H2 reoxidation; when H2 generated at a cathode travels to an anode and anodic biofilms use H2 as an electron acceptor, which exhibits low current density. A 3D printed reactor was equipped with a DES that provided well-mixed conditions and was inoculated with biofilms from an anaerobic digestor and fed with fermented corn stover effluent. A 3D printed single-chamber BES equipped with a DES showed 3.3 times higher current densities (~53 A/m2) than a conventional single-chamber BES without a separator (~16 A/m2). In control abiotic electrochemical experiments, a DES exhibited significantly higher (P=0.03) proton conductivity (456±127 µSmm 1) than a proton exchange membrane (67±21 µSmm-1). A DES effectively reduced H2 migration (21-fold vs. control) to the anode. Overall, a DES in a single-chamber BES improved anodic current density by decreasing the H2 reoxidation at the anode.