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Sewage treatment: papermaking wastewater treatment

Introduction: Papermaking wastewater is difficult to deal with wastewater, and will produce papermaking black liquor, black liquor contains lignin, cellulose, volatile organic acids, smell, pollution is very strong.
Source: Paper industry using wood, straw, reed, rags and other raw materials, high temperature and high pressure cooking and separation of cellulose, made of pulp. In the production process, the final discharge of raw materials in the non-cellulose part of the papermaking black liquor. Black liquor contains lignin, cellulose, volatile organic acids, smell, pollution is very strong. Paper industry wastewater is a kind of water, large color, high suspended matter content, high concentration of organic matter, complex composition of difficult to deal with organic wastewater.
Characteristics of Papermaking Wastewater
Papermaking wastewater is very harmful, of which black water is the most harmful, it contains pollutants accounted for more than 90% of the total pollution of the paper industry pollution, due to large black water, deep color, smell heavy, And a large number of dissolved oxygen dissolved in water, serious pollution of water, to the environment and human health hazards. The middle of the water pollution is the most serious bleaching process of chlorine wastewater generated, such as chlorinated bleach wastewater, hypochlorite bleaching wastewater. In addition, bleach waste contains highly toxic carcinogens dioxin, but also on the ecological environment and human health poses a serious threat.
Papermaking wastewater classification
Pulp and papermaking wastewater composition is very complex, its composition depends not only on the pulp method, but also depends on the species and the type of raw materials and other factors.
Pulp and papermaking wastewater can be divided into: pulp cooking liquor, washing wastewater, bleaching wastewater and paper machine white water. Alkaline pulp cooking waste, also known as "black liquor", is the main source of pulp mill.
The main component of papermaking wastewater
Pulp and papermaking wastewater composition is very complex, its composition depends not only on the pulp method, but also depends on the species and the type of raw materials and other factors.
The suspended matter in the waste water of the paper industry is mainly from the bark, the grass and the sediment of the preparation section, and the wastes, fillers and so on which the ash, slag and pulp and paper are discharged with the water. The BOD in the waste water mainly comes from the pulping Cooking processes such as carbohydrates, alcohols, organic acids and the like produced by decomposition of cellulose.
In the chemical pulp, the amount of BOD5 in the cooking waste is more than 80%. The COD and the coloring material in the wastewater are mainly derived from the lignin and its derivatives in the pulping process. The toxic substances in the wastewater are mainly in the cooking waste (Such as dichlorophenol, chlorinated catechol, etc.), as well as trace amounts of mercury, phenols and the like, but these are usually very small amounts of toxic substances, which are related to bleach wastewater In the organic chloride toxicity and "three" role in the developed countries has attracted more and more attention. Sewage treatment: papermaking wastewater treatment
Papermaking wastewater treatment
Physical chemistry:
In the depth of papermaking wastewater treatment, the physical and chemical method has the advantages of fast governance and good treatment effect. The general methods include advanced oxidation method, flocculation precipitation method, membrane separation method and adsorption method.
1, advanced oxidation method
Advanced oxidation (AdvancedOxidationProcesses referred to as AOPs), also known as deep oxidation technology, is developed in the 20th century, 80 years for the treatment of refractory organic pollutants a new technology. In the oxidant, electricity, sound, light irradiation, catalyst and other effects under the strong oxidation capacity (its potential 2.80V, second only to the fluorine of 2.87V [-OH] and then through the [-OH] and organic compounds plus Such as substitution, substitution, electron transfer, break-off, ring-opening and so on, so that the degradation of organic matter in wastewater degradation of macromolecules into low toxicity or non-toxic small molecular substances, and even directly decomposed into CO: and H: O, The purpose of harm.
The technology has the advantages of quick reaction speed, high treatment efficiency, complete destruction of toxic pollutants, no secondary pollution, wide application range and easy operation, and is widely used in toxic and difficult industrial wastewater, such as pharmaceutical, fine chemical, printing and dyeing And other organic wastewater treatment, has gradually become a difficult task of refractory wastewater treatment research.
According to the generation of free radicals and reaction conditions, can be divided into Fenton oxidation, supercritical water oxidation, photocatalytic oxidation, ultrasonic oxidation, electrocatalytic oxidation, ozone oxidation and wet oxidation.
2, flocculation precipitation method
Flocculation and sedimentation method is the polymerization product formed by flocculant, through a series of effects, the suspension of water, colloidal macromolecular mass pollutants removal method. For the three-stage treatment of pulp and papermaking wastewater, this method has been widely used. Under the operating conditions, the CODcr of wastewater can be reduced from 1416mg / L to 48.9mg / L by flocculation-electrospray.
3, membrane separation method
Membrane separation method is a special semipermeable membrane will solute and solvent separation, so that one side of the solution of a solute through the membrane or solvent penetration, so as to achieve the purpose of separation of solvents.
The results showed that the COD removal rate of the system was 73.1, which was higher than that of the BS system (48.6%), and the removal rate of COD was 73.1, which was higher than that of the BS system (48.6%). The acidity of MBS is 20.1% and the acidification level is 7.5%, which is slightly better than that of BS system (when the COD load is 6kg- (m3-d) -1) is better than that of BS system (in the case of anaerobic sludge activity and running stability. 7.0% and 5.0%).
4, chemical method
Chemical method is by adding a specific chemical agents (such as the United States Kano COD degradation agent), to reduce the pollutant index of a professional agent, the agent has a high removal rate, the reaction speed, with less, easy to add, use Convenient and no secondary pollution of environmentally friendly products, the end of the vote can be directly discharged. 【Recommended Use】
Sewage treatment: papermaking wastewater treatment
COD degradation agent combines the oxidation, reaction sedimentation, adsorption and other technologies, can be in the sewage COD and other pollutants from the water quickly removed, only 2-3 minutes reaction time, is the preferred agent for wastewater COD exceeded.
Suitable for the treatment of any COD wastewater. Is specifically for the industry wastewater soluble COD difficult to remove and special research and development of new chemical agents, the removal of COD has a significant effect, with the Division of other products use, the effect is better to ensure stable COD to meet national emission standards.

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