By taking the circulating cooling water blowdown treatment process of Huaneng Chaohu Power Plant as a typical case

the process of purifying the circulating cooling water blowdown of thermal power plants using a combined physicochemical-biological process to meet the discharge standards was investigated

and the contribution rates of different process units to the removal of various pollutants were evaluated. The results show that

the combined technology of physicochemical and biological

including biological aerated filter

coagulation clarifier

ozonation contact reactor

biological activated carbon filter and quartz sand filter

could achieve efficient and stable treatment of circulating cooling water blowdown in thermal power plant

and after treatment

the water quality could meet the relevant requirements of Class IV in the Environmental Quality Standards for Surface Water(GB 3838—2002). The biological aerated filter and biological activated carbon filter realized the efficient removal of nitrogen and organic matters in the circulating cooling water blowdown of thermal power plants. Coagulation clarifier and biological activated carbon filter played an important role in the removal of turbidity

total phosphorus

dissolved total phosphorus and phosphate in circulating cooling water blowdown

while the quartz sand filter at the end of the process ensured the stable discharge of effluent turbidity. The ozonation contact reactor could not only greatly improve the biodegradability of the circulating cooling water blowdown

but also facilitated the further purification of pollutants in the followed biological treatment unit. The study provides important reference for the treatment of circulating cooling water blowdown in thermal power plants with similar water quality and discharge requirements.