An example of wastewater treatment project in a chemical pharmaceutical enterprise

In view of the high concentrations of total nitrogen and ammonia nitrogen in the production wastewater of a chemical pharmaceutical enterprise, which contained a large number of organic compounds that were difficult to biodegrade, with a large change in acidity and alkalinity of the water quality, a combined process of two-stage ammonia nitrogen blow-off + comprehensive regulation + hydrolysis and acidification + two-stage A/O+ coagulation and precipitation was adopted to treat the wastewater. The optimal process parameters of ammonia nitrogen blow-off were analyzed and studied. When the pH was adjusted to 11.5, and the gas-liquid volume ratio was controlled to 3 500∶1, the blow-off rate could reach more than 90%. The operation results showed that the removal rates of NH₃-N and TN in the ammonia nitrogen blow-off treatment unit both reached 94%. After two-stage A/O and secondary sedimentation tank treatment, the removal rates of COD_Cr, NH₃-N and TN reached 91.1%, 96.3% and 91.0%, respectively. After the combined process, the effluent pollutant concentrations were COD_Cr≤50 mg/L, NH₃-N ≤8 mg/L, TN ≤15 mg/L, SS ≤10 mg/L, and the quality of the treated water reached Grade Ⅰ level A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants (GB 18918-2002), and the processing cost was 2.429 yuan/m ³.