Efficient treatment of high-strength refractory wastewater via micropressure internal circulation reactor:...

This study aims to address the engineering challenge that single-stage biological processes are ineffective for high-concentration, hard-to-degrade industrial wastewater. This is a micropressurized internal recirculation reactor that the study utilized to treat high-concentration, low-biodegradability electroplating rinse wastewater. The chemical oxygen demand and total nitrogen removal rates reached 98 % and 97 %, respectively, and the effluent linear alkylbenzene sulfonate concentration was reduced to less than 10 mg/L. The mixed liquor suspended solids was maintained at 11,126 mg/L, and no excess sludge was produced. The dissolved oxygen gradient distribution within the reactor enhanced degradability, with the main degradation pathway-extracellular polymeric substance adsorption followed by biological oxidation (representing 69 %). Metabolic analysis showed substantial promotion in the system's energy metabolism and electron transfer functions. The degradation pathways for typical pollutants, containing siloxanes and long-chain alkanes, were elucidated. The results of this study provide new methods and theoretical support for single-stage biological treatment of industrial wastewater.