re-aerobic treatment and dissolved oxygen regulation in full-scale aerobic-hydrolysis and denitrification-aerobic process for achieving simultaneous detoxification and nitrification of coking wastewater

Abstract

The biological treatment of coking wastewater is a challenge. The application of prepositioned aerobic process has rarely been systematically reported, among which the detoxification and nitrification performance of the prepositioned aerobic unit (O1) is worthy of investigation. Results indicate that O1 achieves stable simultaneous detoxification and nitrification by regulating the dissolved oxygen, effectively maintaining ammonification, nitrosation, and complete nitrification phases. Microbial community structure, metabolic pathways and functional genes showed different preferences at different phases. High dissolved oxygen concentrations (2.20–3.00 mg/L) benefited the enrichment of carbon and nitrogen related major metabolic pathways and functional genes. BOD₅/COD_Cr ratio, dissolved oxygen and toxic pollutants together shaped microbial community structure and nitrogen transformation processes. Based on the principle of DO regulation, it could assemble a biotransformation compartment for nitrogen removal from complex wastewaters through a pollutant detoxification mechanism of rapid microbial proliferation，and provides a promising approach for toxic industrial wastewater.