Characteristics Of Algac Bloom Of Water Supply And Algae Removal With The Chemical Mothod Of Tijian City In North China

The main characteristics and the affecting factors of algae bloom of municipal water supply in Tianjin were analyzed.It was found that algal vigorous growth occurred from June to September in recent years. During this time both the monthly average algae density and lasting time increased year after year. The main algae forming algae bloom was Cyanophyta and the dominant generas were Microcystis. The accumulation of nutrients (such as total nitrogen and total phosphorus) with high concentration, high temperature of water and strong sunshine caused the algae bloom.The efficiency of algae removal by four algaecides for Luanhe River water was studied. The experimental results showed that in the condition of this experiment four algaecides all had strong removing rate on algae, and their removing rate increased with dose increasing, and decreased with algae density increasing. According to the removing rate on algae and cost value or so, the sequence of four algaecides from good to bad were potassium permanganate, copper sulfate, hydrogen peroxide and sodium hypochlorite.In the condition of this experiment, the suitable dose of potassium permanganate was 0.8mg/L, the algal removing rate was beyond 90% and the cost of this algaecide was only 0.0068 /m3.The efficiency of algae removal by four algaecides for Huanghe River water was studied.The results showed that the majority of Huanghe River water was Bacillaroiphyta, and the dominant genera was Melosira,which reached 78%~94%. The algae removing rate of four algaecides increased with dose increasing, and the sequence of four algaecides' removing rate on algae from high to low were potassium permanganate, sodium hypochlorite or copper sulfate and hydrogen peroxide. The suitable contact time of four algaecides was also given.The paper compared with the rate of algae removal by any one of three algaecides for two source water. It was found that the rate of algae removal by any one of three algaecidesfor Luan -he River water was higher than that for Huanghe River water, in the condition of the same medicamental dose and algae density.