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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The types and stages of polyacrylamide for papermaking wastewater used from paper mills are widely used in water treatment in the papermaking field. Its role is to reduce the consumption of raw materials and pollution to the environment. The effect used in papermaking depends on its average molecular weight, ionic properties, ionic strength and the activity of other copolymers. Cationic polyacrylamide is mainly used for the treatment of papermaking wastewater and filtering aid. In addition, it has a good effect on improving the retention rate of filler.

The papermaking wastewater contains high levels of COD and suspended solids (SS) and serious color. The concentration of SS and COD in papermaking wastewater is relatively high. COD is composed of two parts: insoluble COD and soluble COD. Generally, insoluble COD accounts for most of the total COD composition. When SS is removed from the wastewater, most of it Insoluble COD is also removed. Therefore, the main problem to be solved in waste paper and papermaking wastewater treatment is to remove SS and COD.

Anionic polyacrylamide for paper mill wastewater, with a molecular weight of about 14 million. Main application: wastewater precipitation.

Cationic polyacrylamide for paper mill wastewater, with a molecular weight of about 12 million. Main application: sludge dewatering.

Types and stages of Polyacrylamide for papermaking wastewater from paper mills. The effect used in papermaking depends on its average molecular weight, ionic properties, ionic strength and the activity of other copolymers. A combination of physicochemical and biochemical treatment is adopted. The general physicochemical and biochemical treatment methods are wastewater → screen → adjustment → precipitation or air floatation → A/O or contact oxidation → secondary sedimentation tank → discharge. In this treatment process scheme, cations are used Polyacrylamide to treat sewage.

Papermaking and papermaking wastewater flocculation and sedimentation treatment of anionic polyacrylamide flocculant, sludge dewatering cationic polyacrylamide flocculant pam, papermaking dispersion of 16 million to 18 million molecular weight polyacrylamide flocculant, papermaking retention retention and filtration quality imported polyacrylamide.

In the papermaking process, the paper fibers and fillers in the pulp are hydrophobic and tend to flocculate into agglomerates, and it is often difficult to produce paper with uniform performance and strength that meets the requirements. It is necessary to add an auxiliary agent to increase the viscosity of the pulp, so as to facilitate the even dispersion of the fibers and fillers, so that the paper produced is even and smooth and flexible without holes, so that the performance of the papermaking is stable, and it is not easy to break the paper and raise the powder during the papermaking. Improve the tensile strength and dry and wet strength of paper products and save paper pulp. The added additive is called paper dispersant.

Paper-making dispersant has high dispersion efficiency, stable coating viscosity, less foam, non-toxic and non-corrosive, can improve the solid content of the coating, and has good fluidity and scrub resistance, can maintain the gloss of the paper product, and is not easy to mold. Paper-making dispersants can also increase the speed of papermaking, save beating time, reduce energy consumption, and have significant economic benefits. It has the characteristics of pyrolysis, its viscosity decreases rapidly with increasing temperature, good water solubility, high viscosity, and good lubricity, so as to ensure that it does not affect the performance of the original fiber in the dried paper. The product is a water-soluble organic polymer, which is easily soluble in water and forms a high-viscosity liquid. It can promote good dispersion of papermaking fibers and excellent paper forming effects at low addition levels, improve pulp uniformity and paper softness , Can also increase the strength properties of paper.

The Papermaking dispersant can show good fiber dispersion effect in a very small amount of addition (less than 1kg per ton of dry pulp). The product is non-ionic, relatively less affected by water quality and other additives, and has stable papermaking performance, and is not easy to break paper and powder. Its advantage is that it can improve the softness and uniformity of the finished paper. The principle of the dispersant is to distribute the solid fine particles as evenly as possible in another incompatible material. That is to say, the internal phase is a coarsely dispersed system composed of insoluble particles distributed in the external phase being liquid or semi-solid. The dispersant can make the solid dispersed particles in the suspension fully wetted and evenly dispersed by the liquid phase, and minimize the separation, aggregation and settling speed of the solid particles in the system to maintain the maximum kinetic stability of the suspension.

Papermaking dispersant can also increase the speed of papermaking, save beating time, reduce energy consumption, and has significant economic benefits. Papermaking dispersants are currently widely used in the production of low-quantitative paper such as toilet paper, newsprint, cigarette paper, tea filter paper, liner paper, napkins, colored crepe paper, electrolytically soluble paper, and electrostatic copy paper.