Discussion on papermaking wastewater treatment process of industrial wastewater来源：环保易交易 作者: 阅读：2313 网友评论0条 Updated: 2019-10-10 10:04 Source: Environmental conveyancing transactions of: Read: 2313 2010 0 comments
The pollution of the paper industry itself is very serious, and it consumes a lot of natural resources in the process of papermaking. What is more serious is that there will be a lot of waste water generated in the papermaking industry, so the development of the papermaking industry is greatly hindered. To promote the healthy development of the paper industry, we need to carry out in-depth research and analysis on the process of zero discharge of papermaking wastewater, control the amount of wastewater discharged by the papermaking industry, and minimize its impact on the natural environment.
1. Significance of wastewater treatment in the paper industry
The papermaking industry will produce a lot of wastewater. The organic matter in the wastewater accounts for 25% of the total organic matter in China's domestic industrial wastewater, which has a serious impact on the natural ecological environment. Therefore, it is necessary to reduce the wastewater discharged by the papermaking industry to achieve papermaking wastewater. Zero emissions. In order to ensure the production and emission reduction of the papermaking industry, it is also necessary to promote the zero discharge of papermaking wastewater. This can not only improve the economic benefits of the papermaking industry, but also achieve the goal of energy conservation and emission reduction, and form better social and environmental benefits. It is also in line with the concept of sustainable development proposed by today's society.
Pulp and papermaking will produce a lot of wastewater, papermaking wastewater has a higher BOD, and there are still many fiber suspended matter in papermaking wastewater. In addition, papermaking wastewater contains divalent sulfur and color. The natural ecological environment produces very serious pollution and impacts. The wastewater also contains black liquor and white water, so it is necessary to effectively clean up the impurity content in the wastewater, reducing the impurity content in the wastewater not only meets environmental protection requirements, but also can improve social economic benefits.
2. A brief introduction to zero wastewater discharge technology
The core of the papermaking wastewater zero-discharge process technology is to recycle the wastewater and realize the second use. Today, Japan, the Netherlands, and some European countries have basically achieved zero discharge of wastewater from the papermaking industry. At present, most of the papermaking enterprises in China are using non-deinking production process technology. In recent years, China has become more and more researched in terms of zero wastewater discharge and wastewater recycling.
3. Application of zero discharge technology for papermaking wastewater
3.1 Wastewater recycling
In order to achieve zero discharge of papermaking wastewater, it is necessary to properly treat the circulating water. However, it is difficult to meet the standards and requirements for zero discharge of wastewater using ordinary physical and chemical methods. The following problems exist in the application process:
3.1.1 Corrosion issues. The papermaking wastewater zero discharge process is generally carried out in a closed cycle system. In the closed cycle system, the temperature of the aqueous solution will be greatly increased, and the content of dissolved matter in the water will rise rapidly. As a result, chemical corrosion will be greatly increased. And electrochemical corrosion, it also produces a large number of bacteria and organic acids, which can also cause corrosion problems.
3.1.2 breed a large number of microorganisms. If the closed circulation device is blocked, it will affect the normal operation of the papermaking machine. If the amount of pulp is too large, it will cause the problem of falling off of the pulp block. Because the temperature in the closed circulation system is very high and contains a lot of organic acids, Under this temperature condition, the growth rate of microorganisms will increase greatly. Too much microorganisms will seriously affect the degradation effect of the additives, and more seriously, it will also generate toxic and harmful gases, which will greatly accelerate the rate of corrosion and form rotten slurry.
3.1.3 Secondary Adhesives. During the papermaking production, many hydrophobic substances are often produced. Generally, these hydrophobic substances are adhesive in nature. Therefore, when making paper, these adhesive substances are often used in Honggang doctor blades and felts and forming nets. Deposition occurs in other places, and if it is serious, it will also block the purifier and screen, eventually causing corrosion problems.
3.2 Common process methods for papermaking wastewater treatment
3.2.1 Ultrafiltration membrane method. Utilizing the ultrafiltration membrane method can realize the purification of papermaking wastewater. The main working principle of the ultrafiltration membrane is: first, apply sufficient pressure to one side of the filtration membrane. In this way, the macromolecular organic matter and small fiber substances in the papermaking wastewater and Suspended matter, microorganisms, etc. will be separated, and eventually the papermaking wastewater will be purified.
When purifying papermaking wastewater, the power pump may be damaged. In order to prevent this, it is necessary to add a self-cleaning filter or a laminated filter in the wastewater treatment process, because it requires a lot of wastewater treatment. This link mainly includes the most basic links such as air flotation, aerobic, anaerobic and precipitation, so in order to better meet the lonely treatment standards and specifications, the settings of self-cleaning filters and laminated filters Is very necessary.
The application of ultrafiltration membrane technology when processing papermaking wastewater is very extensive, because this technology has many advantages, and this technology can effectively remove and separate pulp fibers and lignin contained in wastewater. At the same time, these materials can be recycled and used to minimize the impurities and other impurities in the wastewater, and to recycle the organic substances and important components contained in the wastewater. In general, the ultrafiltration membrane process technology is used to clean up Wastewater impurities consume less energy and are consistent with the concept of sustainable development.
3.2.2 Reverse osmosis method. The reverse osmosis method is often used in the treatment of papermaking wastewater. This method of treating papermaking wastewater can effectively remove a large amount of salt contained in the wastewater. In this way, the water quality of the wastewater will be improved. The wastewater has a good concentration effect. By this method, the concentration of papermaking wastewater can be increased, and the effective components contained in the wastewater can be effectively retained.
The concentration of wastewater produced by papermaking using the nitrite method is very dilute, and the energy consumed when treating the papermaking wastewater by the RO method is not much, and the wastewater concentrated by the RO method is evaporated when it is evaporated. Consumption can also be effectively reduced.
3.2.3 Technical methods of electrodialysis membrane. Papermaking wastewater usually has a lot of complex organic impurities, so it will cause serious pollution to the permeable membrane. In order to ensure the cleanliness of the permeable membrane, the permeable membrane needs to be cleaned frequently. The use of electrodialysis membrane method can effectively clean the papermaking wastewater, can recycle the alkali contained in the papermaking wastewater, can also effectively extract the polyxylose contained in the papermaking wastewater, and can remove organics in the wastewater. The salt content of the material.
3.2.4 Ceramic membrane filtration method. In the treatment of papermaking wastewater, ceramic membrane reuse technology is often used. This technology has many advantages. First of all, ceramic membranes are easy to clean, have a long service life, and have reproducibility, plus their pore size. It is uniform and has high corrosion resistance. In addition, the mechanical strength and rigidity of the ceramic film are relatively high. More importantly, the ceramic film has the characteristics of high temperature resistance.
Generally speaking, the temperature of the papermaking wastewater sedimentation tank is about 80 ¡ã C. In order to avoid the subsequent processes not being affected, the temperature of the wastewater treatment should be reduced. We can use the cooling tower spray method, but when using this method to reduce the temperature A lot of hot gas rises with it, which causes serious pollution to the natural ecological environment. Therefore, ceramic membranes can be used to filter papermaking wastewater. In this way, thermal energy can be recycled, which not only reduces environmental pollution but also improves In view of the economic benefits, it can be known that it is very advantageous to use ceramic membrane filtration to treat papermaking wastewater.
Nowadays, China strongly advocates sustainable development and environmental protection. Therefore, all walks of life in China have begun to focus on sustainable development. The paper industry is a very polluted industry. Under the new situation of development, the paper industry has also begun to transform and upgrade. Enterprises must combine their own production processes, improve wastewater treatment technologies and methods, and effectively treat wastewater generated from papermaking. At the same time, they need to compare and analyze different wastewater treatment methods to choose the most effective wastewater treatment method to promote wastewater. The improvement and optimization of the treatment process finally reached zero discharge of wastewater in the paper industry.
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