The paper industry uses wood, straw, reeds, rags, etc. as raw materials, and separates cellulose through high-temperature and high-pressure cooking to make pulp. In the production process, the non-cellulose part of the discharged raw material becomes papermaking black liquor. The black liquor contains lignin, cellulose, volatile organic acids, etc., which is odorous and highly polluting. Polyacrylamide for papermaking wastewater.
Papermaking wastewater mainly comes from the pulping and papermaking processes in the papermaking industry. Pulping is to separate the fiber from the plant raw materials into a slurry, and then bleach it. This process will produce a large amount of papermaking wastewater;
Papermaking is the process of diluting, shaping, pressing, and drying the pulp into paper. This process is also prone to papermaking wastewater. The papermaking wastewater produced by pulping has serious pollution. The waste water discharged during pulp washing is dark brown, called black water. The concentration of pollutants in the black water is very high, the BOD is as high as 5-40g/L, and it contains a lot of fibers, inorganic salts and pigments. The papermaking wastewater discharged from the bleaching process also contains a large amount of acid and alkali substances. The papermaking wastewater discharged from the papermaking machine is called white water, which contains a large amount of fibers and fillers and rubber materials added during the production process. Polyacrylamide for papermaking wastewater.
Polyacrylamide for wastewater treatment in paper mills
Papermaking wastewater treatment should focus on increasing the recycling water rate, reducing water consumption and wastewater discharge, and actively exploring various reliable, economical and capable of making full use of useful resources in wastewater treatment methods.
For example: the flotation wastewater treatment method can recover fibrous solids in white water, the recovery rate can reach 95%, and the clarified water can be reused; the combustion wastewater treatment method can recover sodium hydroxide, sodium sulfide, sodium sulfate in black water and combine with organic matter Of other sodium salts. Neutralization wastewater treatment method adjusts the pH value of wastewater; coagulation sedimentation or flotation method can remove suspended solids in wastewater; chemical precipitation method can decolorize; biological treatment method can remove BOD, which is more effective for kraft paper wastewater; wet oxidation method treats sulfite pulp Wastewater is more successful. In addition, there are also paper-making wastewater treatment methods at home and abroad that use reverse osmosis, ultrafiltration, and electrodialysis.
The papermaking process of recycling waste paper can be divided into two parts: pulping and papermaking. In the process of deslagging, pulp washing and rinsing in the pulping part, a large amount of washing wastewater is generated. According to the difference of waste paper source and production process, the characteristics of washing wastewater are different, and its pollutant content is roughly: CODCr 600～2400 mg/L, BOD5 125～585 mg/L, SS 650～2400 mg/L, color The temperature is 450 to 900 times, and the appearance is dark gray. The amount of washing wastewater is 100-200 t/t of paper; like the usual papermaking process, in the papermaking part of papermaking by reusing waste paper, "white water" containing fibers, fillers and chemicals is also produced. This wastewater is often used The air floatation method is used to process, recover fibers and fillers, and make the treated "white water" recycled.
Papermaking wastewater is a kind of industrial wastewater that is difficult to treat. Generally, the pollutants in it can be degraded through physical and chemical methods + biochemical methods. Since the pollutants contained in the wastewater itself are very complex, after treatment, although the effluent can basically meet the discharge standard, it is far from the water quality requirements of wastewater reuse. It is achieved by traditional sand filtration, activated carbon filtration, and multi-media filtration. Wastewater reuse treatment only reduces the concentration of suspended solids in the effluent to a certain extent, and the soluble pollutants such as COD, ammonia nitrogen and salt in the sewage cannot be further removed. If reused, it will directly affect the paper effect. Generally, the reuse of reclaimed water in the papermaking industry is often limited to production processes that do not require high water quality such as slag removal, pulp washing, rinsing, etc., and the water used in these sections has certain requirements for COD, turbidity, iron and other indicators. The existing filtration The technology cannot meet the water quality requirements of these sections, and the traditional multi-stage filtration process has the disadvantages of long process flow, large area, and unstable water quality. The advanced reclaimed water treatment process must be adopted to further reduce the concentration of iron and COD in the water on the basis of the original sewage discharge up to the standard. On the one hand, it can be directly used as reclaimed water for slag removal, pulp washing, rinsing and other water quality requirements. On the other hand, the treated reclaimed water can be directly desalinated by reverse osmosis or ion exchange, eliminating the need for multi-level security filtration and ultrafiltration in the reverse osmosis process, reducing pre-treatment costs and extending the service life of RO membranes.
Polyacrylamide for paper mills
The special polyacrylamide used in paper mills is used in the paper industry to improve the retention rate of fillers and pigments. In order to reduce the loss of raw materials and environmental pollution; the second is to increase the strength of the paper (including dry strength and wet strength). In addition, the use of PAM can also increase the tear resistance and porosity of the paper to improve the visual and printing performance. Used in food and tea packaging paper.
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