Abstract: This paper deals with the purification efficiency of sewage pond under natural condition. Regression analysis is conducted among pollutant contents (including TN . TP> CODcr, BOD5) in influent and effluent, and water temperature, so as to set up the interrelation equations among these parameters. The effects of environmental factors on the purification efficiency of sewage pond are discussed. 

Key words: sewage pond, purification efficiency, water temperature, regression analysis