THE INFLUENCING FACTORS AND OPTIMAL OPERATION OF PHOSPHORUS REMOVAL IN URBAN WASTEWATER TREATMENT PLANTS

With the new round upgrading of urban sewage treatment plants in key river basins across China, some sewage treatment plants reduced their total effluent (TP) emission limit from 0.5 mg/L to 0.3 mg/L, and even to 0.2 mg/L, which posed a new challenge for phosphorus removal in urban sewage treatment plants. In this paper, by investigating and analyzing 58 urban sewage treatment plants that implement the Grade I-A Discharge Standard in China's national standard GB 18918-2002, we discussed the main problems of phosphorus removal in the actual production and operation of sewage treatment plants and gave corresponding countermeasures for future high-standard TP emissions, in order to provide technical guidance for the operation and management of the sewage treatment plant. The survey results showed that the phosphorus release potential of each sewage treatment plant was in the range of 0.01~23.98 mg/(g·h), and the average phosphorus release potential was 2.77 mg/(g·h). The phosphorus release potential was generally weak; insufficient carbon source in the feedwater, high concentration of nitrate nitrogen in the anaerobic zone, and the inhibition of simultaneous chemical phosphorus removal were the main reasons for the poor biological phosphorus removal effect, and specific control measures were proposed accordingly. In addition, it was recommended that the sewage treatment plant determined the best phosphorus removal agents and appropriate dosage by static experiments according to the quality of the incoming water, so as to achieve more reasonable control of the chemical phosphorus removal process, thereby achieving the purpose of saving phosphorus removal agents consumption.