Interactive effect of electrode potential on pollutants conversion in denitrifying sulfide removal microbial fuel cells

Abstract

The denitrifying sulfide removal microbial fuel cell (MFC) provided an approach for treatment of wastewater containing both sulfide and nitrogenous compounds, but the production of sulfate and nitrite need to be prevented. The interactive effect of electrode potential on sulfide and nitrate conversion was investigated using potentiostatic three-chamber MFC. Both abiotic and biotic processes involved in anodic sulfate formation. Rising anode potential led to an increase of sulfide removal rate and a decrease of sulfur formation percent. The suitable anode potential favoring both sulfide removal and sulfur recovery ranged from −188 mV to −146 mV. The nitrate removal rate and gaseous nitrogen formation percent showed an increase followed by a decrease along with the rise of cathode potential. The suitable cathode potential favoring both nitrate removal and gaseous nitrogen formation ranged from −181 mV to −125 mV. Regulating cathode potential through varying the external resistance was feasible, achieving the optimal sulfur formation percent (32.4 ± 1.9%) and gaseous nitrogen formation percent (92.5 ± 0.3%) at a cathode potential of −139 ± 37 mV. The potentiostatic three-chamber MFC is a suitable configuration for investigating the effect of electrode potential on pollutant conversion because its uncontrolled electrode could simulate the electron driving force situation occurring in a MFC.