| Based on the city recreational water as the main study object, for water eutrophication, study the different aperture flat micro-filter membrane’treatment effect for recreational water, best operating parameters, membrane fouling characteristics and cleaning methods, etc. The ladder flux method was used to confirm the critical flux of flat micro-filter membrane, and pollutant particle size was analysed; In the pilot test, the operation of flat micro-filter membrane was analysed; Different chemicals was used to clean the pollution membrane, compared the change of the membrane flux of before and after cleaning.After small test and medium test, obtained the following conclusions:in no any pretreatment,0.1,0.2and0.3μm membrane have very good removal efficiency on the SS, turbidity, chlorophyll a and algae. The removal rate was all above90%. But for TN, TP, ammonia nitrogen and organic matter, remove effect is bad, the removal rate under30%. Three kinds of different diameter micro-filter membrane compared,0.1μm membrane of the smallest aperture have best removal for the various contamination. In the treatment of the recreational water, the critical flux of0.1μm membrane is100L/m2.h, the critical flux of0.2and0.3μm membrane are120L/m2.h. When recreational water is treated by flat micro-filter membrane, the influence order of several major pollutants on the flux is:humic acid> algae> suspended solids. According to particle size analysis of the recreational water pollutants,150nm is the boundary of recreational water pollutants, in recreational water, pollutants size is mainly concentrated above the150nm. If no any pretreatment, three kinds of different diameter membrane compared,0.1μm membrane have best effect removal for the various contamination, the anti-pollution capacity is most powerful, the smallest aperture of0.1um membrane is more suitable to dealing with recreational water. Treating recreational water with micro-filter membrane alone, the membrane pollution rate is very soon and can not steadily operate. Flocculation pretreatment can make small molecules together to be macromolecular particles, reduce membrane pore jam with small molecules, slow membrane pollution rate, which is beneficial to the long-term stability operation of micro-filter membrane. When use flocculation-microfiltration process dealing with recreational water, the specific operating parameters as following:flocculant is PAC, dosage is10mg/L, and operating mode is intermittent operation-run16min, stop aeration4min,0.1μm membrane operating flux is100L/m2h,0.2and0.3μm membrane operating flux is120L/m2.h. Flocculation-microfiltration process have very good removal effect on the SS, turbidity, chlorophyll a and algae, Compared with single using micro-filter, improve the removal efficiency of TP and organic matter, can remove almost all of the TP in the water, the removal rate efficiency of organic matte increase to about55%.When recreational water is treated by flocculation-microfiltration process, three kinds of micro-filter membrane all have very good removal efficiency on various contaminant, pressure of0.3μm membrane is minimum, flux is maximum, so power costs is also the lowest,water output is maximum,0.3μm membrane is more suitable for dealing with recreational water when increasing the flocculation pretreatment. After some time running, flat micro-filter membrane will-produce severe membrane fouling, must use chemical to cleaning it, chemicals is0.5%NaOH and200mg/L of citric acid, the cleaning cycle for a month. The cost of flocculation-microfiltration process of dealing with recreational water is0.802yuan/m3, water quality is good and stable, flocculation-microfiltration process is suitable to be used as processing equipment of replenishment and circulating water of small-scale recreational water. |
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