Improved dechlorination and mineralization of 4-chlorophenol in a sequential biocathode–bioanode bioelectrochemical system with mixed photosynthetic bacteria

• The biocathode BES with PSB could enhance the dechlorination at cathode.
• Light responses were performed to ascertain the role of PSB.
• Dechlorination and mineralization were achieved with sequential biocathode–bioanode.
• The performance could be improved with PSB inoculation in both cathode and anode.

A new approach that improved the dechlorination and mineralization of 4-chlorophenol (4-CP) was demonstrated in a sequential biocathode–bioanode bioelectrochemical system (BES) with mixed photosynthetic bacteria (PSB). The biocathode with additional PSB inoculation showed higher 4-CP dechlorination efficiency (DE) and maximum current (81.8 ± 2.9%, 0.021 ± 0.002 A) than that at abiotic cathode (45.3 ± 3.7%, 0.011 ± 0.002 A) (P < 0.005). Light response in biocathode BES with or without PSB ascertained the important role of PSB played in the dechlorination and current generation. Dechlorination and mineralization of 4-CP was achieved in the sequential biocathode–bioanode BES, which could be further enhanced with PSB inoculation in both cathode chamber and anode chamber. 4-CP DE in the cathode chamber was improved from 55.0 ± 2.0% to 78.8 ± 4.9%, and the phenol degradation in the anode chamber was improved from 65.3 ± 2.1% to 71.3 ± 1.4%. This study directed a new way for improving dechlorination at biocathode and product degradation at bioanode with PSB inoculation in BES.