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​How To Deal With Paper Industry Wastewater
- Jul 06, 2018 -

How to deal with paper industry wastewater?

Papermaking wastewater mainly comes from the two production processes of pulping and papermaking in the paper industry. Pulping is to separate the fibers in the plant raw material, make a slurry, and then bleach; the paper is to dilute, shape, press, and dry the slurry to make paper. Both processes discharge large amounts of wastewater. The wastewater produced by pulping is the most polluted. The waste water discharged during washing is dark brown, called black water. The concentration of pollutants in black water is very high. The BOD is as high as 5-40g/L, which contains a lot of fiber, inorganic salt and pigment. The wastewater discharged from the bleaching process also contains a large amount of acid and alkali substances. The waste water discharged from the paper machine, called white water, contains a large amount of fibers and fillers and rubbers added during the production process.

The treatment of paper industry wastewater should focus on increasing the recycling rate, reducing water consumption and wastewater discharge, and actively exploring various reliable, economical and fully utilizing treatment methods for useful resources in wastewater. For example, the flotation method can recover fibrous solid materials in white water, the recovery rate can reach 95%, and the clarified water can be reused; the combustion method can recover sodium hydroxide, sodium sulfide, sodium sulfate and other sodium salts combined with organic substances in black water. The neutralization method adjusts the pH value of the wastewater; the coagulation sedimentation or flotation method can remove the suspended solids in the wastewater; the chemical precipitation method can decolorize; the biological treatment method can remove the BOD, and is effective for the kraft paper wastewater; the wet oxidation treatment of the sulfite pulp wastewater success. In addition, reverse osmosis, ultrafiltration, electrodialysis and other treatment methods are also used at home and abroad.