| The shortened process is described about the source water after appropriate pretreatment directly into the submerged ultrafiltration membrane filter, completed the concentrated water recycling and sludge thickening in the membrane pool, filtered water add a small amount of disinfectant then enter the clear pool. Compared with the traditional process, precipitation weaken, water quality greatly enhanced, treatment process shortened, area significantly reduced, the highlighted advantages make "the short process treatment with the core of submerged ultrafiltration membrane" receive more and more attention after first put forward. This short process-type ultrafiltration technology will be the most promising water treatment technology in the field of water purification field.In the tests coagulation and powdered activated carbon were used as the pre-treatment of shortened static pressure flowed submerged ultrafiltration membrane, membrane fouling and the pollutant removal efficiency micro-polluted source water were studied. The pollutionmechanism and control measures of a flat membrane of the shortened process is also be studied. While combine the two pretreatment methods, the results showed the removal of pollutants is improved, the situation of membrane fouling are better than using only coagulation pretreatment. And make the the zeolite and powder kaolin as two pre-coatings, the filtration dynamic mathematical model is built about the relationship of filtration resistance of short processed ultra-membrane membrane and the changed turbidity and TOC with time varys.The results show that in some certain water quality conditions the short processed ultrafiltration membrane using pre-coated can improve the membrane flux, and reduce membrane filtration resistance.According to membrane filtration dynamic mathematical model the best pre-coating in the different water quality conditions can be optimized. The main results are as follows:(1)Coagulation pretreatment of UF shortened process, the use of PAC compared with ferric chloride on membrane fouling control is more effective; turbidity removal rate between99.04%-99.94%, high cloud degrees ferric chloride coagulation better; permanganate index removal rate from40%to50%, PAC coagulation better; UV254removal rate from23%to43%in between; feed aqueous ammonia concentration was0.95mg/L-1.11mg/L, coagulation pretreatment removal rate was10.53%-14.41%, while the coagulation while adding powdered activated carbon, the removal rate gradually increased from the14.02%to51.5%. Combining the two pretreatment on membrane fouling improve the situation better than using only the coagulation pretreatment.(2)When TOC=4.85mg/L, turbidity=4.21NTU, the membrane flux decreased growth rate and transmembrane pressure, without pre-coating of42.48%and36.36%, the use of pre-coated kaolin powder was28.32%and34.31%, pre-coated zeolite powder and32.35%for the31.53percentZeolite and kaolin powder coating method combines two pre shortened process ultrafiltration membrane flux decreases and the rate of decline in the growth rate of transmembrane pressure, the membrane resistance is reduced and delayed membrane fouling, through anti-rinse during operation can be effectively attached to the membrane surface area of dispersed precoat rinse.(3)Create two pre-coated and not containing added under the pre-coated membrane filtration resistance over time and the quality of raw water turbidity and TOC changes include a mathematical model. According to the mathematical model shows that:①When turbidity is between2.67-11.75NTU and39.57-107.6NTU, the use of pre-coating kaolin powder is better, when turbidity<2.67NTU, the use of pre-coated zeolite powder is good.②When the TOC <3.201mg/L, the use of pre-coated powder is preferably kaolin, when TOC>6.71mg/L, the use of the zeolite powder is better. The remaining cases the model and then determine the membrane filtration resistance calculated using the powder with kaolin or zeolite powder precoat. |
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