Comparison of Performance in a Bioelectrochemical System for Simultaneous Denitrification and Vanadate (V) Removal Using Hydrogen as the Sole Electron Donor

Abstract

An auto-hydrogenotrophic bioelectrochemical system (BES) was set up to investigate the performance of removing nitrate (NO3−–N) and vanadate (V(V)) simultaneously. In this BES, hydrogen is produced during electrolytic reactions and the microorganisms on cathode biofilm can use it as the electron donor to reduce NO3−–N and V(V). This experiment confirmed that the removal efficiency of nitrate and vanadate could be improved by increasing the electric current and extending the hydraulic retention time (HRT) appropriately. The optimal electric current for the reactor was 200 mA with the optimum denitrification efficiency of 94.12%, vanadate removal efficiency of 77.55%. The optimal HRT was 12 h with the optimum denitrification efficiency of 94.40% and vanadate removal efficiency of 86.71%. However, by increasing the influent concentration of V(V), the removal efficiency of NO3−–N and V(V) were both reduced. These findings may help to reveal the biogeochemical fate of V(V) and nitrate in aquifers and develop technology that can simultaneously remove them from groundwater.