| Since the pollution of the surface water has been more and more serious in China,the coagulation sedimentation-filtration- disinfection water treatment process has been unable to meet the requirements of the drinking water quality standard which becomes more and more stringent recently. It is urgent to reseaarch and develop some new type water treatment technologies. In the background of the lack of water, water pollution,the limited treatment and the strict standards, membrane separation technology emerge as the times require. With the characteristics of high quality water, larger filter area, convenient installation and operation,Immersed Ultrafiltration membrane talent showing itself among the membrane technology. Nowadays, most waterworks of our country are being reformed, membrane process and ozone activated carbon process are added in the conventional process. It not only increase the lengths of water treatment process but also improve the cost of water treatment. How to make full use of the existing water treatment unit and upgrade reasonably is a considerable problem that worth thinkinng and explorating, so the coagulation-precipitation-ultrafiltration and coagulation-ultrafiltration process have gradually become the focus of attention.Due to the different water quality in different regions and waters, it is very necessary to carry out targeted research,exploration,and master the operation of technical parameters which can be used to provide references for engineering and application before the UF membrane shorted process will be taken into actual engineering application.According to the actual demand of water supply of Cangzhou,The UF shorted process experiment carried out in Qingyuan Waterworks which located Cangzhou city and the source water comes from Dalangdian reservoir. The reservoir can be divided into the following periods: low temperature and turbidity water period, normal water period and high temperature and high algae period according to the source water display different characteristics in different water periods. The shorted process experiment just experienced all water periods since the operation run and it has a high reference value. The main work completed as follows:First, make a continuous detection on membrane effluent and focus on the treatment effect among shorted process,long process and conventional process with these indicators : turbidity, organic matter,algae,microbes,metal ions and so on.Second,the parameters of filteration and empty cycle is controled and adjusted, the optimal filtration cycle is 60 minutes when the empty cycle is 5 hours; and then the transmembrane pressure is taken as the research object when the dosage and running flux are taken as the control variable so that the best operating conditions of membrane treatment process is studied out. It finds that the transmembrane pressure stable in a certain range with the slowest membrane fouling when the coagulant dosage in 6~10 mg/L,the coagulant aid dosage in 0.2~0.5 mg/L and the running flux in 30L/(m2·h).Once again, cleaning conditions on membrane fouling are compared and optimized, including cleaning agents,cleaning concentration and reaction time, the transmembrane pressure recovery rate is used as evaluation basis of the cleaning effect.The conclusion as follows: the agent of maintenance washing is Na Cl O with 500 ppm and the agent recovery of washing is Na Cl O with 1000 ppm, Na OH with 0.5%,HCLwith 0.5%. The transmembrane pressure recovery rate is always above 90% which shows a good cleaning effect.Last, Si, tryptophan and tyrosine aromatic protein are detected in a high content by analysing the cleaning liquid ingredients of the fouling membrane which indicating that these protein substances are the main material that causing the membrane fouling.The UF membrane shorted process not only have a good water quality,stable operation, high water production rate, but also save area and reduce investment in infrastructure.In view of the advantages of energy saving, technology promotion prospects. |
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