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Guangzhong is an important manufacturer of disc separators in China, and many series of separators are widely used in the industries of yeast, starch, rubber, medicine, and biochemistry.

Membrane separation: small technology

[Abstract]:
In recent decades, membrane separation technology has been widely used in the fields of energy, electronics, petroleum,...
In recent decades, membrane separation technology has been widely used in the fields of energy, electronics, petroleum, chemical, pharmaceutical, health, heavy industry, light industry, food, beverage industry, people's daily life, and environmental protection. The demand of society has led to the rapid development of membrane technology, which has enabled membrane technology to continuously innovate, improve, and improve, becoming the key to the integration process.
 
Membrane separation technology will enter the stage of large-scale application for the deep treatment and reuse of industrial wastewater in China. Petrochemical, chlor-alkali chemical, papermaking, steel, and power industries have successively established demonstration projects and promoted the industry. The project scale has been processed Ton level into the 10,000-ton level.
 
At present, the separation and purification of products in the chlor-alkali industry, pesticide chemical industry, and pharmaceutical chemical industry have been widely used for the purification of raw material intermediates, such as purification of pale brine, recovery of glyphosate mother liquor, separation and purification of antibiotics, and improvement of separation efficiency. At the same time, it greatly reduced energy consumption. Under the circumstances of the country's strong promotion of energy conservation and emission reduction, the development of membrane separation technology will have important and far-reaching significance for the chemical industry and even for energy conservation and emission reduction in all walks of life.
Membrane separation technology "Main" petrochemical energy-saving and emission reduction
 
In general, microfiltration technology is widely used in petroleum wastewater treatment.
 
The 0.2μm and 0.8μm ceramic membranes produced by the Institute of Membrane Science and Technology, Nanjing University of Chemical Technology were used for onshore and offshore oil production platforms. After proper pretreatment, good results were obtained. The suspended solids content decreased from 73 to 290 mg/L to less than 1 mg/L, and the oil moisture content decreased from 8 to 583 mg/L to less than 5 mg/L. For the most critical cleaning problems in membrane processing, pulse and pretreatment processes were designed to effectively extend the filtration cycle. At the same time, according to the pollution characteristics of the surface water produced by the oil on the membrane surface, the cleaning scheme for the alternate use of two cleaning agents, B and C, was determined. And verified the pretreatment process, cleaning process, repeatability and stability of the pulse process, laid the technical foundation for industrial scale-up test.
 
The results show that the flocculation treatment can significantly reduce the petroleum concentration and COD in the water phase. The flocculation treatment is combined with the 0.2 μm zirconia membrane filtration treatment. The concentration of oil and COD of the permeate can reach the national emission standards. Based on the concentration of oil in the effluent after flocculation treatment, a suitable flocculant was identified as 3530S. The appropriate flocculation treatment conditions were determined by orthogonal test. The flocculant was 70mg/L, the temperature was 40°C, and the mixture was stirred for 90 minutes. The rest time is 1.5h. Flocculation can reduce membrane fouling and increase membrane permeation flux. The effects of operating pressure and cross-flow rate on permeate quality and membrane permeation flux were investigated, and appropriate operating conditions were determined.
 
However, the amount of oil-bearing wastewater in the oil field accounts for about one-third of the total wastewater volume in the oil field, and the composition is complex. Ultrafiltration technology is used to treat the oil-bearing wastewater from the oil field, which can not only pollute the environment and water but also provide high-quality oil field reinjection. With water. Ultrafiltration membranes were used to retreat oilfield pretreated wastewater, and experimental studies have demonstrated that the membrane-to-oil interception rate of wastewater treated by UF membranes is above 97.7%, and the water quality index can reach the injection station of low pressure infiltrated oil fields. Water injection standard.
 
The external pressure tube type polysulfone ultrafiltration membrane device was used to treat oil production wastewater on site. The effects of operating conditions such as operating pressure and membrane surface flow rate on ultrafiltration membrane flux and membrane fouling cleaning methods were studied. Under appropriate operating conditions, The membrane flux is 80~490L/m2h, and the treated sewage reaches the water injection standard for low-permeability oilfields. The method of step-by-step cleaning can effectively remove dirt on the membrane surface, providing basic data for further industrial test equipment amplification.
 
According to the specific conditions of the petrochemical plant designed for wastewater treatment and reverse osmosis pretreatment used ultrafiltration equipment, and the use of modified PVC material, resistant to pollution, anti-oxidation. The reverse osmosis selection is LFC1 anti-pollution membrane, ultra-filtration treatment of sewage, to ensure the effluent turbidity is less than 1.0NTU, SDI value is less than 3. After reducing the turbidity, it can fully meet the requirements of the downstream reverse osmosis water inflow, and ultimately achieve the reliable operation of the entire water reuse system.
 
The hollow fiber ultrafiltration membrane was used to test the reinjection water at Daqing Oil Field Water Injection Station. The membrane module developed was 1-4 times larger in flux than conventional hollow fiber modules, and it was stable at a pressure difference of 0.08 MPa. When the amount reaches the maximum, the flux recovery reaches more than 95% after cleaning with the self-contained cleaning solution.
 
Hollow fiber ultrafiltration membrane was used to treat oily wastewater in oil fields. The results showed that the total suspended solids concentration decreased from 6.69 mg/L to 0.56 mg/L, and the oil quality concentration decreased from 127.09 mg/L to 0.5 mg/L. Membrane separation Technology is one of the feasible and effective methods for advanced treatment of oily wastewater.
 
The use of U.S. Abcor's tubular ultrafilters for the treatment of synthetic latex wastewater was tested. The test results showed that the removal rate of pollutants in the ultrafiltration treatment of latex wastewater can reach more than 80%, creating favorable conditions for biochemical treatment.
 
The inorganic ultrafiltration membrane was used to filter vegetable oil plant wastewater. The results showed that the interception rate of inorganic oil in the wastewater was as high as 99.5%. The inorganic membrane was used to treat the wastewater from the vegetable oil plant, achieving an oil rejection rate of 99.7%.
 
Liaohe Oilfield uses the MBR-aeration biological filter (BAF) process to treat oil production wastewater. This method can effectively remove pollutants, oil, BOD5, ammonia nitrogen, etc. in the oil production wastewater, with a removal rate of more than 90%. The water is clear and transparent, and has no odor. Oil effluent can reach the standard discharge, without adding chemicals. In order to ensure the stability of the MBR effluent quality, the powdered activated carbon can be placed in the MBR to increase the removal efficiency of the MBR for low-concentration contaminants and to effectively reduce membrane fouling.
 
"Test water" chlor-alkali chemical energy-saving emission reduction
 
With the rapid development of China's chlor-alkali industry in recent years, how to treat and recycle a large amount of waste water in the production process of chlor-alkali has become an important issue for enterprises.
 
The denitrification process in the chlor-alkali industry is divided into chemical denitrification and membrane denitrification. The chemical denitrification process adopts calcium denitrification in the environment with less sulfate, denitrification using the deuterium method in the environment with more sulfate, and denitrification with the deuterium method if chemical denitrification is used according to the quality requirements of the original salt. The one-time investment of the technology is small, and the 200,000 t/a scale investment is about 800,000 yuan, but the operating cost is large. The annual consumption of barium chloride is 4400 tons, and the annual cost is about 9.68 million yuan. At the same time, strontium chloride will produce secondary pollution in the process of use, and it is difficult for fine barium sulfate to settle. At the same time, because gallium chloride cannot be fully converted, it may damage the ion membrane and cause damage to the ion membrane, which will affect the service life of the ion membrane. Membrane denitrification process is divided into the denitrification of the Kay membrane and the removal of the Gore membrane. This process has good denitrification effect on the brine and there is no problem of environmental pollution.
 
The traditional salt water sulfate removal process adopts the hydrazine method because of environmental reasons and the toxicity of cesium chloride itself.
For price reasons, membrane denitrification can currently be used instead of this process (CIM process). It is estimated that in the case of one-off investment, the investment in the CIM method will exceed that of the deterrence method by more than 4 million yuan. In terms of subsequent operating costs, it can save 2 million yuan each year, plus other operating expenses, and 4 million yuan in additional investment. Can be recycled in 1 to 2 years.
 
As the main process of PVC synthesis, the deionized water used in the suspension process PVC production process is discharged as a centrifuge mother liquor after the polymerization reaction is completed and becomes the main source of the entire production wastewater. Because the content of calcium and magnesium ions is very low, the mother liquor of the centrifuge is contaminated soft water. In recent years, many units have carried out research and development in the treatment and reuse of centrifuged mother liquor, introduced some processing technologies, and have carried out industrial applications in succession.
 
In recent years, the reuse of recycled water and the recycling of wastewater have become the focus of energy-saving and emission reduction work in all walks of life. Among the various technologies for the reuse of reclaimed water and the recycling of waste water, the integration of wastewater reuse membranes developed on the basis of pure water preparation and seawater desalination has undoubtedly become the most popular application technology. In large and medium-sized wastewater and reclaimed water reuse projects, as long as high-quality, deep-recycled projects are involved, ultrafiltration and reverse osmosis double-membrane combination processes are used as the core process, and other physical and chemical or biochemical technologies are also supported. To ensure the operation of the double-film process.
 
At present, the research and application of separation technologies mainly focus on the selection and determination of rational selection of membrane types and treatment process parameters; surface modification of membranes to reduce membrane fouling; exploration of appropriate cleaning cycles with appropriate cleaning agents and cleaning processes; and simultaneous development. New technology, development of high-pass, anti-pollution new membrane materials. The above problems have been solved successfully. The application of membrane separation technology in energy conservation and emission reduction in chemical industry and its industry will become more and more extensive.