Autotrophic biocathode for high efficient sulfate reduction in microbial electrolysis cells

Abstract

The aim of this study was to utilize the biocathode microbial electrolysis cell (MEC) for sulfate removal from wastewater. Experiments were conducted using the two-chambered MEC under fed-batch and continuous flow modes, respectively, with different cathode potentials. With the fed-batch operation, the average reductive rate of sulfate was 0.49 mg d(-1) and the sulfide concentration increased to 3.1 ± 0.7 mg L(-1) in the catholyte. Sulfate removal rate and electron production rate in the continuous flow mode were 49% and 11 times higher than in the fed-batch mode. With cathode potentials from -0.6 to -1.0 V, electron recovery efficiencies ranged from 5.3% to 50% with the maximum obtained at -0.8 V. The maximum sulfate removal efficiency of (39 ± 9.2)% was achieved at -0.9 V. This study suggests the MEC can be a valuable alternative to remove sulfate in wastewater treatment.

Keywords: Biocathode; Microbial electrolysis cell; Sulfate reducing bacteria; Sulfate reduction.