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Water treatment in the "membrane era" should develop strengths and circumvent weaknesses

urban domestic sewage and industrial sewage are the top priority of environmental protection in the 12th Five Year Plan. Membrane technology is the established direction in the selection of technical route

at present, membrane technology has become an important technology in the water treatment industry, and more than 90% of membrane materials in China are also used in water treatment. However, the author learned last week that although water treatment has entered the era of membrane, many experts pointed out that only when the magical membrane technology is organically combined with traditional processes can it improve its functions and overcome the cost

urban domestic sewage and industrial sewage are the top priority of environmental protection in the 12th Five Year Plan. The 12th Five Year Plan for the development of energy conservation and environmental protection industry has set specific scale targets for sewage treatment and solid waste treatment in the next five years. By 2015, the daily treatment scale of new sewage nationwide will reach 90million tons, twice the elevation of the 11th five year plan, and the upgraded sewage treatment scale will be 50million tons. Membrane technology is the established direction in the selection of technical route

Zhou Baiqing, the director of the Department of water quality engineering of Wuhan University, who edited the book "full membrane water treatment technology", introduced to the author that microfiltration, ultrafiltration, reverse osmosis and electric desalting are the four most commonly used membrane separation technologies in the field of water treatment at present, which have many advantages over traditional coagulation, clarification, filtration and other technologies

the problem of water pollution in China is very prominent, and the composition of sewage is complex. In practical engineering, only using traditional technology can not solve the problem. Using and mastering membrane separation technology will help to design a diverse and increasingly perfect water treatment system. However, he also pointed out that the full membrane water treatment process, which completely relies on membrane technology in water treatment, including the organic combination of ultrafiltration, microfiltration, reverse osmosis, electrodeionization and other different membrane processes, is difficult to achieve in production, and the application of reagents is inevitable. For example, refractory coking wastewater also needs biochemical treatment

Zhou Baiqing believes that the development trend of water treatment technology is the intersection and integration of new and old technologies, so as to realize the advantages and avoid disadvantages. For example, he said, organic wastewater has complex components, high concentration and salt content, high chromaticity and toxicity, and some of them are substances that are difficult to biodegrade, especially the three carcinogenic (carcinogenic, teratogenic, mutagenic) organic pollutants that do great harm to human health. It is difficult to make the effluent discharge up to the standard by a single treatment process, and the existing processes must be integrated

many experts said that membrane technology should be treated dialectically: on the one hand, it is indeed progressiveness; On the other hand, it should also be integrated with other technologies. The traditional water treatment process is still very useful

Huang Huayao, director of Xuzhou water treatment research institute, believes that although the application conditions of membrane technology are relatively harsh, such as the requirement that the particle diameter in water is not greater than 5 microns, it has the most advantage for sewage treatment with high salt content. Up to now, there is no other better way to deal with high salinity sewage. However, he also pointed out that the membrane method does not save water. He also said that sewage treatment is a systematic project, which requires a systematic approach, and there is no universal technology. A variety of treatment technologies have their own advantages and disadvantages. Only the combined application technology content is higher and the treatment scheme is more perfect

Ren Qingchun, chairman of Beijing Ziguang Yitian Environmental Engineering Technology Co., Ltd., further introduced to the author that reverse osmosis membrane plays a leading role in water treatment, and the theoretical water recovery rate is 75%

according to the survey results of hundreds of users across the country, in actual operation, the finished water rate of desalted water is only 55% - 60%, and more than 40% of the wastewater is only a small part used for spraying or other purposes in coal plants, and most of it is discharged. Some users feel distressed about the 40% waste water discharged in vain. In order to improve the reuse rate, they invest in a set of anti elasticity - the ability of the material to return to its original shape after the load that causes its deformation is removed. The infiltration device will recycle it, but nearly 20% of the concentrated water is still discharged

Ren Qingchun told the author that at present, there is no more economical and applicable technology to realize zero discharge of enterprise sewage. If membrane technology is used, the treatment cost per ton of water is as high as about 7 yuan, which is not economical. Zero discharge of sewage requires efficient removal of pollutants and deep desalination. In view of the high cost, high requirements for water quality and poor system operation stability of membrane technology, experts agreed that membrane technology needs to be combined with traditional treatment processes to overcome the economic barrier, so as to solve the problem of recycling water. Zheng long, President of China synthetic resin supply and Marketing Association, said: "although metal materials have always occupied a dominant position in the automotive industry, deep treatment has been a problem to realize the recycling of water resources

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