With the continuous development of science and technology, the technology of wastewater treatment and resource-making of pulp and paper is changing day by day. The traditional wastewater treatment and reuse technology has been constantly innovated and developed, and at the same time, many newer and more advanced technologies have emerged. For the treatment of black liquor, alkali recovery is still the most economical and effective way. However, the alkali recovery equipment needs high investment, with an investment of about 8000-10000 yuan per 10000 tons of pulp. The minimum production scale requires more than 50t pulp per day. Therefore, the alkali recovery method is mainly used in large paper mills. For medium and small paper mills, acid analysis can be considered to treat black liquor, while the new flue gas acid analysis method can achieve the effect of waste to waste, which is a better choice; slag coagulant can also achieve better effect and low treatment cost; the black liquor can be used for sulfur fixation combustion supporting agent, which makes the black liquor resource-based use. The reliable technology of the treatment of middle water is two-stage biological treatment, and the combination of physicochemical method and biological method has good treatment effect on COD; the combination of photocatalytic oxidation and biological method has a good decolorization effect on the middle water.
The treatment and reuse of white water is now mature. Air flotation is a technology which is widely used at present. After white water treatment, it can be reused and fine fibers in white water can be recycled. Membrane separation method has good effect on white water treatment, but the treatment cost is high, which is the direction of future development, and further research is needed.
There are many methods for the treatment of paper waste water, but each method and process has its own advantages and disadvantages. Even very advanced processing methods can not complete the processing tasks independently. It is often necessary to form a processing system by several methods to complete the required processing efficiency. Generally speaking, the pollutants in wastewater are various, and they also have their best treatment methods. According to different water quality and the enterprise's own conditions, the most suitable wastewater treatment system can be selected.
Wastewater should be recognized from a new perspective. Wastewater and resources are in opposition and unity. Wastewater can be regarded as resources to be developed. As long as the technology passes through and measures are appropriate, the waste water can be transformed into resources. From this point of view, the "zero emission" of pulp and paper mills can be achieved. It will be beneficial to solve the problem of water pollution in the future by considering the method of treating sewage with new ideas.