How to treat wastewater from the paper industry?

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.
Papermaking is to dilute, shape, squeeze, and dry the slurry to make paper.
Both processes discharge large amounts of waste water. Wastewater from pulping is the most polluted.

The wastewater discharged from 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 wastewater discharged from the bleaching process also contains a large amount of acid and alkali substances.
The waste water discharged from the paper machine is called white water, which contains a large amount of fiber and fillers and rubber materials added in the production process.
The treatment of wastewater from the papermaking industry focuses on increasing the recycling rate, reducing water consumption and wastewater discharge, and actively exploring various reliable, economical and capable of fully utilizing the useful resources in wastewater treatment methods.
The flotation method can recover fibrous solids 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 matter in black water. The neutralization 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.
The wet oxidation process is more successful in treating sulfite pulp wastewater. There are also treatment methods such as reverse osmosis, ultrafiltration, and electrodialysis.
A large-scale paper industry sewage treatment project in Guangdong: The system mainly treats the discharged sewage from the papermaking production line, with a cooling system designed to handle 60000m³/d. The heat exchange method is adopted to exchange heat and reduce the temperature of the sewage, so that the temperature of the effluent reaches the target of ≤37°C.

In response to this working condition, Jiema has fully considered the working environment of the project in the selection of heat exchange equipment, and has taken anti-corrosion and anti-rust measures. The use of a special plate heat exchanger effectively solves the purpose of heat exchange and cooling of sewage and improves the recycling rate of sewage.

Jiema’s products are widely used in all aspects of papermaking industry: