| A waterworks in Dalian carries responsibility for drinking water supplied in development zone of Dalian city,which headwater is Biliu reservoir.The existing water treatment process has been lagging to some extent due to the improved water quality standard.Especially,when the contradiction between the production of water and the water quality happens,water treatment is not effective,prone to falling problems of low turbidity rate.Accordingly,the study of enhanced coagulation rule,upgrading the existing technology for improving the treatment effect and impact resistance are main purpose.In view of the existing problems,from improvement of coagulant,this paper studied the optimum coagulation conditions for improving the quality of yielding water and enhancing the impact on water quality variation of the original traditional technology to reduce the treatment costs.In this paper,a comprehensive analysis of water quality index was carried out.Two stages: low temperature,turbidity stage and high temperature,turbidity stage were mainly studied.Coagulants,optimizing conditions of different stages and water quality were conducted by beaker mixing experiments.Finally,upgrading the existing treatment was carried out to enhance the impact resistance of water quality by traditional treatment.The research results are as follows:(1)The best experiments conditions of PAC were confirmed.PAC could be used as the raw water treatment coagulant,because of cheap,simple operation and suitable for the present treatment technology.(2)Low temperature and low turbidity conditions,four kinds of coagulant showed good decolorizing effect,four kinds of coagulants had good coagulation effects,turbidity removal efficiency was above 70%,the highest reached 94%.Different coagulant on the removal of turbidity in the precipitation time was different.With the precipitation time increase,the turbidity decreased,four kinds of coagulant showed good coagulation effect,and the aluminum salt,ferric salt to turbidity were analyzed.(3)High temperature and high turbidity conditions,the index would be higher,so the four kinds of coagulant on the removal of turbidity were not high.Four kinds of coagulants on oxygen consumption,ammonia removal and algae had certain contribution.The ammonia nitrogen removal rate could be as high as 90%,the algae removal rate up to 61%,and the causes of index removal are analyzed.According to the actual water treatment process,considering the cost,PACS was ideal for water treatment.(4)Low temperature and turbidity,high temperature and turbidity conditions,the removal rate of turbidity of composite coagulant were higher than that of single PAC.At the color removal,adding PAM and PPF to further enhance the color removal,algae removal rate can reach 92% by adding PPF.Turbidity and oxygen consumption removal were enhanced by adding PAM.(5)Considering the use of PAM as a coagulant,the optimum dosage range of PAM was0.03-0.1 mg/L.The optimum dosage of PAM should be after adding PACS.(6)Considering the raw water was changed with seasonal variation,investment,working and management,mechanically mixing,wave shape flocculation reaction tank and reverse flow inclined sedimentation tank were employed to enhance the impact resistance of raw water. |
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