A Study On The Experiments Of UF For Slow Flowing Freshwater

China is a country that scarce of freshwater in the world, its average freshwater resource per capita is lower than the world′s 1/4. Many main water system such as Changjiang River, Yellow River, Songhuajiang River, Hai River, Huai River are polluted seriously, and the eutrophication is very prominent in slow flowing water. The waterworks which adopts conventional crafts and regards rivers and lakes as the source of water faces rigorous test.Ultra-filtration(UF) can dispose not only most suspended substance, colloid subst- ance but also dissolved organism. UF becomes an important process used in water treatment in recent decades, and will be used more and more extensive.Xingsha Water Supply Company regards Songya Lake as the source of water,and adopts the regular craft:raw water-coagulation,pre-chlorination-gas-floatation-sedimentation-sand-filtration-chlorin-disinfection. There is abundant of alga in raw water from July to September every year, a great deal of alga usually cause filter-stopping, higher turbidity and chroma of effusion, increasing the chlorine consumption,endangering the Security of drinking water.In order to improve the efficiency of alga-removing by conventional water treatment process and offer referential information to the development of integrative drinking water treatment equipments, This paper mainly studied the characteristics of ultra-filtration for the raw water, raw water which adding alum, effusion of sedimentation pond and water taken from a farm lake in Xingsha town utilizing hydrophilic modified PAN hollow fiber ultra-filtration membrane filters. The results show that UF is efficient for the removal of alga, Microcystin and turbidity;There is no obvious removal of Fe, Mn and normal removal for organic substance in the water by UF. After flocculation, the removal of COD_Mn,UV₂₅₄ , Fe, Mn will enhance. According to the results,this paper suggests adopting the improved process:raw water - coagulation - gas-floatation - sedimentation - UF - chlorin-disinfection. According to the regulation of degressive effusion flux of UF during the period time of alga-blooming, This paper also favors the optimum function parameter of UF. When the water temperature is 30℃, the optimum TMP is 0.07MPa, the optimum hydraulic re-wash period is 40min, the optimum chemical wash period is 330min; When the water temperature is 20℃, the optimum TMP is 0.07MPa, the optimum hydraulic re-wash period is 60min, the optimum chemical wash period is 960min.