Principles followed in the treatment of industrial wastewater by self-cleaning filters

1. Prioritize the use of non-toxic production techniques to replace or reform backward production techniques, as far as possible to eliminate or reduce the production of toxic and harmful wastewater during the production process.

　　2. In the process of using toxic raw materials and producing toxic intermediate products and products, strictly operate and supervise, eliminate drips, reduce losses, and use reasonable processes and equipment as much as possible.

　　3. Wastewater containing highly toxic substances, such as some heavy metals, radioactive substances, high-concentration phenol, cyanide wastewater, should be separated from other wastewater in order to treat and recover useful substances.

　　4. Wastewater with large flow and light pollution should be properly treated and recycled, and should not be discharged into the sewer, so as not to increase the load of urban sewer and urban sewage treatment.

　　5. Organic wastewater similar to urban sewage, such as food processing wastewater, sugar wastewater, and papermaking wastewater, can be discharged into the urban sewage system for treatment.

　　6. Some biodegradable toxic wastewater, such as phenol and cyanide wastewater, should be treated first, and then discharged into the urban sewer according to the agreed discharge standard, and then further biochemically treated.

　　7. Contains toxic waste water that is difficult to biodegrade and should be treated separately and should not be discharged into urban sewers. The development trend of industrial wastewater treatment is to recycle wastewater and pollutants as useful resources or implement a closed loop.

Phenol-containing wastewater mainly comes from coking plants, gas plants, petrochemical plants, insulating materials plants and other industrial sectors, as well as the production process of petroleum cracking to produce ethylene, synthetic phenol, polyamide fibers, synthetic dyes, organic pesticides and phenolic resins. Phenol-containing wastewater mainly contains phenol-based compounds, such as phenol, cresol, xylenol and nitrocresol. Phenol-based compounds are a kind of protoplasmic poison that can coagulate proteins. When the mass concentration of phenol in the water reaches 0.1 to 0.2 mg/L, the fish meat will have a peculiar smell and cannot be eaten; increasing the mass concentration to 1 mg/L will affect fish spawning, and the phenol content is 5-10 mg/L. Will die in large numbers. Phenol in drinking water can affect human health. Even if the mass concentration of phenol in water is only 0.002mg/L, disinfection with chlorine will produce chlorophenol stench. Usually the phenol-containing wastewater with a mass concentration of 1000mg/L. It is called high-concentration phenol-containing wastewater. This kind of wastewater must be treated after phenol recovery. Phenol-containing wastewater with a mass concentration of less than 1000mg/L is called low-concentration phenol-containing wastewater. Usually this kind of wastewater is recycled and phenol is concentrated and recycled for treatment. Methods of recovering phenol include solvent extraction, steam stripping, adsorption, and closed loop methods. Wastewater with a mass concentration of phenol below 300mg/L can be treated by biological oxidation, chemical oxidation, physical and chemical oxidation and other methods before being discharged or recycled.