The Study On Clarifier Membrane Filtration Process For Drinking Water Treatment

Along with China's economic development and people's living standards'enhancement, a large number of industrial effluent and residents sewage has not achieved the emission standard directly to disperse into the natural water body, which has created the enormous destruction for the water environment, resulting in sharp decline in water quality of drinking water sources, and serious impact on the people's health and the orderly development of the society. The new drinking water standards implementation and requirements for drinking water quality continuous improvement, the conventional treatment processes have been unable to satisfy under the new form the security tap water supplies need. In present paper the water from Luanhe River, which is the typical and representative ground water in the northern region, was taken as the model sample, the Clarifier-Membrane filtration technology was used as the technology for drinking water treatment research. To deal with the process performance, operating conditions, the membrane fouling and cleaning methods, such as a comprehensive evaluation for it used in drinking water treatment to provide a reliable theoretical basis.First, according to raw water quality characteristics filtered the coagulants which is the suitable coagulant for membrane filtration process, and the pollutant removal efficiency and the impact on membrane fouling had been studied. Though the study, found that the floc size and its impact on the removal efficiency of organic pollutants directly affect the membrane fouling, the greater floc size and the removal efficiency of organic pollutants, the membrane fouling much lower. The view of comprehensive evaluation that the iron-based coagulant for the membrane filtration process is superior to Al-based coagulant, from the benefit-cost ratio for ferric chloride coagulation as pretreatment of membrane filtration technology is effective and economical use.Secondly, the paper has innovatively taken clarifier technology and immersion membrane filtration process combined treatment of drinking water. Comparison of new technology and Coagulation-Membrane filtration process, both of them has almost identical water quality, the former was the lower membrane fouling than the latter; After about nine months running test, in various water quality period of Luanhe the new process was stable, membrane fouling was under control, to prove that the technology is feasible. Response surface methodology firstly applied for the new process to run the operating conditions optimized process, has obtained the best operating conditions.Third, had carried on the earnest analysis in the membrane fouling which influence membrane process. It had been found that the membrane resistance and cake layer is composite to the most of the membrane filtration resistance. The experiments showed that after the effective coagulation pretreatment compared to other resistance membrane resistance become the main factor. After the study of chemical cleaning the different period water quality of different membrane fouling, consider sodium hypochlorite with hydrochloric acid cleaning can be good to restore membrane performance.Finally, this article firstly establish backwashing model based on the mass transfer mechanism, determined the theoretical relationship between backwashing pressure, backwashing flux and the backwashing effective length in the course of backwashing. And the test data of Clarifiers-Membrane filtration process was used to validate the backwashing model, the result show that the backwashing model can better simulation, prediction and evaluation the backwashing operation process. The model for determining the operating conditions of the backwashing provides a more complete theoretical basis, it is effective in reducing the cleaning agent consumption in the backwashing process, improves the production efficiency of membrane process.