Abstract: The water supply of the chemical water treatment in Heilongjiang Yadian Xinbao Heat and Power Corporation Limited is the water of Nenjiang River. Before 2004, the effluent water of the clarifier often was not qualified, and the phenomenon of serious water quality deterioration was occurred in flood period of almost every year. Based on experiment of long time, the reasons influencing on the effluent water quality of clarifier in different period were analyzed indepth, and concrete solving measures were put forward. Then the difficult problem of effluent water quality disqualification had been thoroughly solved.

Key words: clarifier, effluent water quality, water quality deterioration, reason analysis, solving measure