The effect of anode potential on bioelectrochemical and electrochemical tetrathionate degradation

- Electrochemical S4O62− degradation was studied with biological and abiotic anodes.
- Bioelectrochemical current production from S4O62− started at 0.3 V vs. Ag/AgCl.
- Electrochemical current production from S4O62− started at 0.5 V vs. Ag/AgCl.
- S4O62− degradation rate was over three times higher in bioelectrochemical system.
- Reaction products from S4O62− differed between biological and abiotic anodes.

The effect of poised anode potential on electricity production and tetrathionate degradation was studied in two-chamber flow-through electrochemical (ES) and bioelectrochemical systems (BES). The minimum anode potential (vs. Ag/AgCl) for positive current generation was 0.3 V in BES and 0.5 V in the abiotic ES. The anode potential required to obtain average current density above 70 mA m−2 was 0.4 V in BES and above 0.7 V in ES. ES provided higher coulombic efficiency, but the average tetrathionate degradation rate remained significantly higher in BES (above 110 mg L−1 d−1) than in the abiotic ES (below 35 mg L−1 d−1). This study shows that at anode potentials below 0.7 V, the electrochemical tetrathionate degradation is only efficient with microbial catalyst and that significantly higher tetrathionate degradation rates can be obtained with bioelectrochemical systems than with electrochemical systems at the tested anode potentials.

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