Quantitative Study on Algal Control by Combination of Pre-chlorination and Pre-ozone in a Certain Water Plant
Algae outbreaks occur periodically from May to October every year in Qingcaosha reservior. In order to solve the problem of quantitative analysis of process operation of algae control in water plant by adding chlorine and pre-ozone before settling tank,the effect of combined chlorination and pre-ozone in water plant on algae removal were studied,and the pre-chlorination and pre-ozone dosage suitable for Qingcaosha source water plant were selected. Through the production test carried out in a certain water plant,the removal rate of chlorophyll-a in the effluent of sedimentation tank and the change rate of trihalomethanes in the effluent water were comprehensively analyzed,and the recommended dosage for the combination of pre-chlorination and pre-ozone was 0.6~0.8 mg/L sodium hypochlorite and 0.6 mg/L pre-ozone. Under these conditions,the chlorophyll-a removal rate of the effluent from the sedimentation tank is 82.02%~83.88%,and the change rate of chlorophyll-a and trihalomethanes in the outgoing water relative to the effluent from the sedimentation tank is 40.63%~52.27% and-14.75%~-31.12% respectively. Selecting the appropriate pre-chlorination and pre-ozone dosage can not only further reduce the algal reproduction level in the water plant,but also play an important role in further reducing the trihalomethane in the factory water during the algal control period.
pre-chlorinationpre-ozonecombined dosingcontrol algalsource water