Abstract: The turbidity, UV254, CODMn, TOC, THMFP and algal removals efficiency were studied by dissolved air flotation (DAF) and sedimentation process in a water treatment plant (WTP) of Tianjin, China. By the experiment, the suitable process to treat the typical north China source water and the rules of pollutants removal were determined. A pilot model with a capacity of 5 cubic meters per hour was constructed. During the treatment of the low temperature and low turbidity source water, the turbidity removal by DAF process was 25% higher than that by sedimentation process, and 8.4% higher in other periods. During the treatment of high temperature and algal bloom source water, the algal removal by DAF process was 9.5% higher than that by sedimentation process. The removal rule for organic mater was almost same in all periods, which was 5% higher by DAF process than that by sedimentation process. The removal for turbidity, organic matter, and algae can reach 97%, 40% and 94% respectively. DAF process adapts to treat the microorganic pollutants water in north China, and the treatment efficiency was better than sedimentation process.

Key words: environment engineering, water treatment, dissolved air flotation process, sedimentation process, microorganic pollution, low temperature low turbidity, algae