Toxicity Identification and High‐Efficiency Treatment of Aging Chemical Industrial Wastewater from the Hangu Reservoir, China

Abstract

The Hangu Reservoir, located in Binhai New Area, Tianjin, China, receives mixed wastewater from a chemical industrial park. The aging chemical industrial wastewater is less biodegradable and contains complex hazardous substances, thus having an adverse effect on local ecological service function of the reservoir and on local economic and social development. In this study, key toxicants in the aging chemical industrial wastewater from the Hangu Reservoir were systematically identified by the toxicity identification evaluations (TIEs), and the treatment efficiency of the aging chemical industrial wastewater was examined and optimized by a municipal wastewater treatment process simulated in a laboratory. According to the TIE results using and wheat seeds as tested organisms, Cl, Cu, Pb, and Zn were identified as key toxicants in the aging chemical industrial wastewater, with concentrations of 7349.11, 0.01, 0.07, and 0.07 mg L, respectively, which were confirmed by subsequent spiking approaches. Based on the TIE results, the aging chemical industrial wastewater could be classified as high-salinity wastewater. The co-treatment of the aging chemical industrial wastewater and municipal wastewater may be an effective and low-cost method. The treatment efficiency of the mixed wastewater increased with an increase in the volume ratio of municipal wastewater to aging chemical industrial wastewater. When the volume ratio was 10:1, the best removal efficiencies of chemical oxygen demand, total N, and total P were up to 85.1, 89.3, and 96.5%, respectively, whereas the toxicity unit of the treated wastewater was reduced to 0.50.