Reclaimed water reuse plant in industrial water treatment projects was applied earlier in the United States. In China, the recycling of industrial water has been highly valued at the policy level. The State encourages reuse and recycling, and restricts industrial water use year by year through five-year planning and water resources planning. In the field of industrial wastewater reuse, the integrated technology of ultrafiltration / microfiltration and reverse osmosis / nanofiltration with high turbidity and salt removal capacity has been widely used in developed countries in Europe and the United States with its reliable application technology and experience, with its advantages of small floor area, less environmental pollution and high degree of automation, and its decreasing cost brought by large-scale production.
Main fields of reclaimed water reuse in industrial water treatment projects
The main water consumption in industry comes from the following areas: (1) cooling water, (2) boiler make-up water, (3) production process water and flushing water.
According to rough statistics, cooling water accounts for the largest proportion of industrial water. About two-thirds of industrial water is cooling water. In the power industry and oil refining industry, the proportion of cooling water is as high as 90%. The treatment of cooling wastewater is relatively simple and can be recycled after treatment. The wastewater treatment process of boiler make-up water is simple and can be continuously recycled. It is widely used in manufacturing industry to produce steam. The water quality requirements of the water produced by the reclaimed water reuse process are closely related to the characteristics and process of the generated wastewater. Compared with the cooling water and boiler make-up water, this part of the water is usually small. However, the pollution degree of the wastewater is much higher. For the chemical, food and textile printing and dyeing industries, the pollution degree of wastewater is very high, and the quality requirements of production water are high, so it is difficult to treat and reuse it as production water, but it can be considered for flushing or miscellaneous use; For the electronics and semiconductor industries, the production water for oil field exploitation can be reused for production process after advanced treatment.
Membrane separation technology is the most commonly used technology for water reuse in industrial water treatment projects, including ultrafiltration and microfiltration technology, membrane bioreactor (MBR) process, reverse osmosis and nanofiltration technology, double membrane combined technology, etc.