(48f) Bioelectrochemical Sulfate Reduction Enhanced Nitrogen Removal from Industrial Wastewater Containing Ammonia and Sulfate

Many industries discharge wastewater containing sulfate (SO₄^2-) and ammonium (NH₄⁺). Low organic carbon/nitrogen ratio and existing SO₄^2- in industrial wastewater limited nitrogen removal efficiency in traditional wastewater treatment processes. Sulfide (S^2-) autotrophic denitrification coupled with heterotrophic sulfate reduction provided an ideal strategy. However, limited electron donors still hindered efficient nitrogen removal. Herein, a microbial-electrochemical sulfate reduction was coupled with sulfide autotrophic denitrification and heterotrophic sulfate reduction to achieve high nitrogen removal efficiency. Benefitting from the microbial-electrochemical sulfate reduction with a biocathode, the total nitrogen (TN) removal efficiency was increased from ~25% to the maximum of ~ 85% with inputting -45 mA electric current. With the help of supplying electrons to denitrification through SO₄^2- reduction, Columbic efficiency was also improved to 61.5%. Through controlling the input current and recirculation rate to increase the turnover numbers (TONs) of SO₄^2--S, high TN removal efficiency can be obtained at various concentration of SO₄^2-. Furthermore, experimental investigations revealed that coupling microbial-electrochemical sulfate reduction could relieve S⁰ deposition and enhance the sulfur recovery, which also contributed to improve TN removal efficiency. Moreover, microbial community analysis showed the main functional bacteria of each process in the coupled system were Desulfatirhabdium, Thiobacillus, Nitrospira and Desulfovibrio respectively. Treating real industrial wastewater, the coupled system also achieved high TN removal efficiency (~75%). Overall, the coupled system provides electrons for the denitrification process through microbial-electrochemical sulfate reduction to obtain a superior TN removal performance, which offered a new approach for efficient nitrogen removal of industrial wastewater containing SO₄^2-.