| Taking Yuqing water supply system which had been contaminated by algae as the study objection and on-site researching base, a lot of tests and analysis on water quality of Yellow River and Yuqing Lake had been done and the water purification efficiency of Yuqing water supply system was evaluated in this paper. Through laboratory experimental research and onsite-compare test and the method of estimations at industrial scale, this paper studied the efficiency of ClO2 preoxidation of water with algae and drawn a conclusion that this technology can strengthen conventional water treatment process, it had a good effect on removing algae and odor with a characteristic of low dose byproduct of ClO2. So the technology should be a feasible and ideal treatment method for water supply source polluted seriously with algae in emergency.The result of test and analysis showed the Yellow River water of Jinan location had been contaminated by algae, the main pollutants were nutrition, algae and organism which was favor for algae reproducing and water eutrophication. Using estimation of single index, the quality of Yuqing water source form Yellow River was graded for V in April 16th, 2001 and was graded for VI in June 17th,2001 with control factor NOx.The research results indicated that the reservoir of Yuqing lake had been in the condition of eutrophication, the main pollutants were nutrition, algae and organism. Total nitrogen was the control factor among the pollutants, the density of algae has reached 106~107cell/L, the main indicating factors of organic pollutants were CODCT and CODMn- The growth of algae which varied in seasons and temperatures reached high level in March and September. The predominant algae were Cyanophyta and Bacillariophyta.The conventional water treatment process of Yuqing has a low removal of algae. The main reasons were that the algae and organism in the water decreased the ability of removing pollutants by coagulations, the algae which grown again in the open sedimentation tank weakened the removal effect of algae by coagulation; because of the accumulation of algae and algae toxin in the filtration tank, the concentration of algae toxin in the effluent increased; by the function of fluid chlorine, the algae and organisms after the filtration will release microalgae toxin and produce a lot of byproduct such as microalgae toxin, sobomyl and so on, meanwhile, the chlorination produce considerable halide and halo-acetic acid and other disinfection byproduct.The result of experiment shows ClO2 is an effective oxidation for removing algae and microalgae toxin.Through experiment of ClO2 preoxidation in Yuqing water supply system, we can find that ClO2 preoxidation can restrain algae growth in the sedimentation tank, the ClO2 can clean the filtration tank steadily which polluted by algae and algae toxin, it can resolve the problem that microalgae toxin and odor-producing organism which would rise after filtratioa Compared to Cl2 preoxidation, ClO2 preoxidation had better efficiency in restraining algae reproducing in sedimentation and had better ability of controlling the matters rising in cell, it also can lower the risk of mutation-making in drinking water.The results also demonstrated that ClO2 in the dose 1.0mg/L could achieve the maximum removal of algae and microalgae toxin, effluent disinfected by 0.5mg/L ClO2 could meet the requirement for drinking water and could also restrain disinfection byproduct The study results of combination of disinfection after filttation and preoxidation by C1O2 in Yuqing water supply system showed the water quality of effluent totally met the drinking water standards of our country, the process showed good effect in removal of odor and microalgae toxin and decrease the production of disinfection byproduct, therefore, it can keep the effect of disinfection in pipeline netUsing steady-pure ClO2 to remove algae in reservoir not only can resolved the sensitive problem that the algae and maters in cell can not remove simultaneously, but also didn't increas...
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