These two days, Ke Zhenyu, project manager of Jiangsu JiuWu High Tech Co., Ltd., is squatting in Nantong Nengda water Co., Ltd. for technical optimization. Through membrane filtration, hydrochloric acid and caustic soda are filtered out of pulping and papermaking wastewater
These wastewater comes from Jiangsu Prince paper company (hereinafter referred to as Prince paper). Nine years ago, also here, Xu Nanping, then assistant governor of Jiangsu Province and director of the Department of science and technology, led the team to use membrane technology to help Prince paper resolve the crisis and start work smoothly. Today, 32000 tons of pulping tail water are filtered and concentrated every day, and the daily treatment capacity of papermaking tail water is about 10000 tons.
Visitors visit "membrane technology sewage treatment plant". Visual china map
Since the 13th five year plan, the average annual growth rate of the total output value of China's membrane industry has been about 15%; In 2019, the total output value of China's membrane industry has reached 277.3 billion yuan, double that at the end of the 12th Five Year Plan.
"In addition to water treatment, China's membrane products are widely used in pharmaceutical, food and other industries, and also exported to Southeast Asia, Germany, the United States and other regions or countries," fan Yiqun, Professor of the Institute of membrane science and technology of Nanjing University of technology and the national special separation membrane Engineering Technology Research Center, told the reporter.
Membrane technology can realize molecular filtration
Water shortage and water pollution are two major environmental problems facing the world. As a new and efficient separation technology, membrane separation technology can separate small molecules, solid particles and other substances in water by using the membrane of special materials and external power. This technology has the functions of separation, concentration and purification, and is efficient, energy-saving and environmental friendly. It can realize molecular filtration. The filtration process is simple, easy to operate, low energy consumption and high efficiency.
"In recent years, high-performance membrane material technology has developed rapidly. Membrane technology is widely used in sewage treatment plants and household water purifiers. With the continuous progress of technology, the cost is also falling rapidly." fan Yiqun, who has dealt with membrane materials for half a life, is a few treasures for the development of membrane materials in China. He said that membrane materials can be divided into water treatment membrane, gas separation membrane, ion exchange membrane and special separation membrane according to their application fields. According to pore size and function, water treatment membrane can be divided into ultrafiltration membrane, microfiltration membrane, nanofiltration membrane, reverse osmosis membrane, etc.
Fan Yiqun introduced that the pore diameter of ultrafiltration membrane is generally less than 0.1 micron. It can filter bacteria, viruses, colloids and macromolecules in water, and can be used in food processing industry. For example, it can filter and intercept soybean protein in the liquid after soybean products processing. The pore diameter of microfiltration membrane is mostly more than 0.1 micron. It is mostly used to treat suspended solids in water, reduce the turbidity of water body, and filter bacteria in water. It is generally used in river purification. As the name suggests, the pore diameter of nanofiltration membrane can reach 0.002 microns. In addition to filtering humic acid, pesticide and fertilizer residues and other macromolecular substances in water, nanofiltration membrane can also filter calcium and magnesium ions and soften water, but it can retain some minerals.
The smallest pore size is reverse osmosis membrane. "The pore size of reverse osmosis membrane is very small, and only water molecules can pass through. It uses the static pressure difference on both sides of the membrane as the driving force to realize the separation of liquid mixtures. It is widely used in seawater desalination and high-purity water production," fan Yiqun said.
Many fields are inseparable from this film
At present, membrane technology has played a great role in the fields of seawater desalination, industrial wastewater treatment, industrial water treatment, municipal sewage regeneration treatment, municipal tap water quality improvement and transformation, household water purifier market and so on.
The application of this technology once turned the tide for Prince paper, a large project in a desperate situation.
In 2012, Prince paper planned to build a sea discharge pipeline for pulping wastewater in Qidong, Jiangsu Province. After the news spread, Qidong people who have been living in fisheries for generations began to worry that papermaking and pulping wastewater will affect ecology and offshore fishery breeding.
At the critical moment, Xu Nanping, academician of the Chinese Academy of engineering and chief scientist of China Membrane Science 973 project, volunteered to lead more than 40 R & D personnel of the Membrane Science Research Institute of Nanjing University of technology to overcome the worldwide problem of "zero discharge" of papermaking and pulping wastewater, put forward a complete set of design processes, dispelled people's concerns and helped local governments and enterprises out of the dilemma.
Nine years later, the scientific research team has carried out technical upgrading again. Ke Zhenyu told Science and Technology Daily: "In the past, there were many impurities and even some corrosive solid wastes in the salt precipitated from the filtered pulping tail water. In this technical transformation process, the concentrated brine produced by reverse osmosis was separated into high sodium chloride concentrated brine and high sodium sulfate concentrated brine, and then the high sodium chloride concentrated brine was made into low concentration acid and alkaline water for production through a new membrane electrolysis unit to replace some purchased chemicals After sodium sulfate concentrated brine enters the evaporative crystallization system, industrial grade sodium sulfate will be produced and can be sold. "At present, they are doing the trial production and operation of the project and are expected to be completed and put into operation in the second half of this year.
In addition to wastewater treatment, the new water treatment technology with membrane technology as the core has become a sharp tool to improve the water environment.
In 2019, Yantian District, Shenzhen will build the first demonstration area for direct drinking of tap water in Shenzhen. Advanced treatment processes such as ozone activated carbon and ultrafiltration membrane will be adopted to improve the quality of factory water and realize the full coverage of direct drinking of tap water.
Importantly, the production of precision electronic devices, including chips, is also inseparable from membrane technology. "At present, the integration requirements of chips are getting higher and higher. This requires that there is no ion between the transistors to ensure that there is no electromagnetic interference between the devices. The production of these transistors requires the use of ultra pure water to ensure that the chip is stable." membrane technology provides strong support for the preparation of ultra pure water, "Fan Yiqun said.
Strengthen the original innovation ability to meet challenges
At this stage, China's membrane industry still needs to break through the limitations of few product types and narrow application fields. For example, membrane products are mainly concentrated in the field of water treatment, accounting for 85% of the membrane market. There are few categories of special functional membrane products for the fields of medicine, energy and material separation. "Membrane products are at the top of the industrial chain, and membrane materials have become the bottleneck for the high-end development of membrane products. Therefore, it is necessary to strengthen basic research, strengthen original innovation and increase the research and development of key technologies." Zheng genjiang, President of China Membrane Industry Association, told reporters.
The weak original innovation ability of membrane and membrane materials is one of the challenges faced by China's membrane industry at this stage. Zheng genjiang pointed out that this is mainly reflected in three aspects: first, the requirements of chemical raw materials for membrane production are high, and ordinary chemical raw materials are difficult to meet the requirements of membrane production, so a lot of optimization and modification research is needed. Second, the four major aspects of membrane formation mechanism, membrane formula, membrane production process and membrane production equipment Key technologies, which support each other, have high closeness and strong matching, need systematic innovation. Third, due to different application scenarios of membranes, the formula, structure, manufacturing process and performance requirements of each membrane are also different, the membrane manufacturing equipment and process are highly targeted, and the technical difficulty is great. The original innovation of these membrane core technologies needs to be strengthened. For example, proton exchange membrane of hydrogen fuel cell and solar energy The localization rate of key equipment for membrane production of some high-end membrane products such as photovoltaic backplane membrane and other new energy membranes, high-performance medical membranes and high-precision separation membranes is low, and some key equipment still needs to be imported.
Zheng genjiang suggested that we should take the development of advanced equipment manufacturing industry as the goal, carry out system research and development around the major common key technologies of membrane equipment and green, efficient and intelligent manufacturing, and strengthen the modularization, intellectualization, mechatronics of mechanical equipment and the generalization, standardization and integration of parts and components. "We should also develop more high-end products, such as ultrafiltration membranes and nanofiltration membranes that can be used for accurate material separation, and membranes that are resistant to high temperature, high pressure and pollution under extreme working conditions."
The total value of membrane industry in the 14th five year plan may reach 500 billion yuan
The total output value of membrane industry in 2019 is mainly composed of membrane and membrane materials, membrane equipment, membrane engineering and membrane supporting equipment, and membrane trade and services. Among them, membrane engineering and membrane supporting equipment account for 27% of the total output value of China's membrane industry, membrane equipment account for 26% and membrane and membrane materials account for 15%. This means that there is a large growth space in the field of membrane and membrane materials.
"With the development of membrane technology, the raw materials of membrane emerge in endlessly. From a few yuan per kilogram of PVC to hundreds of yuan per kilogram of polytetrafluoroethylene, from fly ash to high-purity alumina, the membranes made of different raw materials have different application scenarios, and we are also trying some new materials, such as ceramic membranes," fan Yiqun said.
"However, the more complex the production and manufacturing process of raw materials, the more expensive the cost." fan Yiqun said, for example, the cost of removing alumina impurities is very high. The market price of 99% purity alumina is about 10000 yuan per ton, while the price of 99.95% purity alumina is as high as 1 million yuan per ton.
"In addition, the uniformity and repeatability of raw materials, the control accuracy and level of production process, and the accuracy and sensitivity of monitoring instruments in production will determine the quality of the film." Fan Yiqun said that in mass membrane production, there should be no defects on the membrane surface. As long as there is a hole with the thickness of hair in a membrane of tens of square meters, impurities will leak through during filtration; in the production process, if dust accidentally falls on the membrane, a hole may also be left on the membrane; these will affect the filtration efficiency.
Facing the "14th five year plan", Zheng genjiang is full of confidence in China's membrane industry. He said: "In recent years, the global membrane market demand has increased rapidly. In 2018, the total output value of global membrane and membrane equipment reached US $95 billion. In the next few years, with the continuous improvement of scientific and technological level, product quality, engineering technology level and international market operation ability, China's membrane industry will quickly integrate into the global market and the international market share will increase significantly."
Zheng genjiang is full of expectations for the future. According to his analysis, the total output value of China's membrane industry may reach 500-600 billion yuan in 2025. Among them, the output value of industrial wastewater recycling, urban sewage reuse, urban tap water quality improvement and transformation, medical membrane and household water purifier will occupy a large market share. "The film industry will also drive the development of 3D printing, medicine, optics, energy and other fields through key common technologies," Zheng genjiang said.
Source: Science and Technology Daily
Editor: Huang Lei
Reviewed by: Yue Liang
Final judge: He Yi
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