In pulp and paper industry, white water treatment has always been a major problem for paper mills. What kind of white water treatment equipment to choose and what kind of white water treatment scheme to use has always been a key issue for paper companies.
What is White Water in Paper Industry?
White water in pulp and paper industry mainly refers to the wastewater produced from paper-making equipment in the process of paper-making. White water contains a large number of fine fibers, fillers and other suspended substances, as well as sizing agents, preservatives, enhancers and so on. It also contains a lot of soluble colloidal substances (DCS). Papermaking process produces a large amount of white water emissions, if not treated emissions, not only to the environment pollution, but also a waste of water resources. In the pulp and paper industry, it is necessary to use white water treatment equipment to purify white water.
The Treatment of White Water in Pulp and Paper Industry
The so-called white water treatment is to remove the substances contained in the white water by certain physical or chemical methods. White water contains many kinds of substances and the composition is complicated.
In order to carry out effective white water treatment, the correct white water treatment method should be used. At present, the main white water treatment methods used in the pulp industry include air flotation, vacuum filtration, flocculation and precipitation, biochemical method, membrane separation method, etc. Next, we will introduce in detail one of the commonly used methods for white water treatment: vacuum filtration.
Use disc vacuum filter treat white water in pulp and paper industry
The main white water treatment equipment required for vacuum filtration is a multi-disc vacuum pulp filter. The disc vacuum filter can effectively recover the fibers and fillers in white water, and is suitable for large and medium-sized pulp and paper mills. Taking a disc vacuum filter with a total filter area of 140 m2 as an example, after filtration, the suspended solid content in white water was reduced from 2153 mg•L-1 to 30 mg•L-1, and the recovery rate was 98.98%. The water consumption per ton of paper has been reduced from the original average of 200kg to 65kg.
The Advantages of Disc Vacuum Filter
- The filtration process of disc vacuum filter is continuous, the process is stable, and there is no negative impact on the papermaking process.
- Good adaptability, the disc vacuum filter has a good effect on the recovery of fiber and filler in all kinds of white water, white water recovery effect on coated paper is also very significant.
- The operating cost is low, and there is no additional cost in addition to the limited power consumption during the operation.
- The recovery rate of fibers and fillers is high, generally up to 95%.
- The disc vacuum filter has high automation and can be controlled by computers and various instruments.
The method of using a multi-disc filter as white water treatment equipment has been widely applied to pulp and paper mills around the world, and has received a very good white water treatment effect. The white water treated by the disc filter can be directly recycled, thereby increasing the degree of recycling of the white water. This white water treatment equipment is popular with many pulp and paper mills.