The pulping and papermaking processes in the paper industry are the main sources of papermaking wastewater.

Pulping is to separate the fibers from the raw materials of trees, make fiber pulp, and then bleach; papermaking is to dilute the fiber pulp, shape, press, dry, and then make paper. Both processes discharge large amounts of wastewater. The wastewater produced by pulping is seriously polluted. The pollutant concentration in the wastewater discharged during pulp washing is very high, the BOD is as high as 10-36g/L, and it contains a lot of plant fibers, inorganic salts and pigments. The wastewater discharged from the bleaching process also contains a large amount of acid and alkali substances. The wastewater discharged from the paper machine contains a large amount of fibers and fillers and sizing materials added during the production process.

The treatment of paper industry wastewater should mainly improve the utilization rate of circulating water, reduce water consumption and the discharge of paper industry wastewater. At the same time, it is also necessary to develop various treatment methods that are reliable, economical and can make full use of the useful resources in wastewater. In addition, * there are also treatment methods such as reverse osmosis, ultrafiltration, and electrodialysis.

Paper industry wastewater is one of the major sources of pollution in the world. Paper industry wastewater contains wood fiber, residual alkali, sulfide and high concentration of organic wastewater. It is characterized by high COD concentration, large amount of waste water, and mercaptan compounds that make paper industry waste water emit a pungent stench.

How to deal with the sewage produced by the paper machine production process?

Paper industry wastewater treatment methods include physical treatment, chemical treatment and biological treatment.

In the physical treatment method, the adsorption method uses the specific surface area of the adsorbent, which has a certain adsorption performance, and separates the organic matter in the papermaking wastewater. Electrodialysis is a membrane separation operation that uses the potential difference as the driving force to remove or enrich the electrolyte from the solution by using the selective permeability of the ion exchange membrane. The sonic membrane electrolysis technology can significantly improve the recovery and treatment effect of papermaking wastewater.

In chemical treatment, hydrothermal oxidation is an effective new chemical oxidation technology. It uses air or oxygen and other oxidants in a hot water tank under the operating conditions of high temperature and high pressure to dissolve and suspend papermaking wastewater. The organic matter in the state or the inorganic matter in the reduced state is oxidized and decomposed in the hot water tank. The wet oxidation method is to use oxygen or air as an oxidant under high temperature (120~400℃) and high pressure (4~25MPa) to oxidize dissolved or suspended organic matter or reduced inorganic matter in water to generate a mixture of carbon dioxide and water. a treatment method.

In the biological treatment method, the aerobic biological treatment method is a method of degrading pollutants with the help of aerobic microorganisms (mainly aerobic bacteria) under aerobic conditions. Anaerobic biological treatment is a treatment technology that uses facultative anaerobic bacteria and obligate anaerobic bacteria to degrade organic pollutants under anaerobic conditions.