1. Coagulation sedimentation: Coagulation sedimentation is a method of purifying industrial wastewater by using coagulants. The coagulants added in sewage treatment are mainly composed of some special chemicals, which can purify the harmful substances in sewage through a series of actions. This method can be used to treat drinking water, industrial water, mine wastewater, oily wastewater from oil fields, domestic water and printing and dyeing wastewater.

2. Biodegradation method: At present, the discharge of printing and dyeing wastewater and papermaking wastewater are the two main causes of environmental pollution. Because many printing and dyeing fuels are composed of aromatic compounds, their structures are complex and it is difficult to degrade them by chemical methods. A little carelessness may lead to water poisoning, so it is better to use biodegradation method for the discharge of this kind of sewage.

3. adsorption method: adsorption method is to treat sewage with adsorbent. At present, magnesium hydroxide, activated cellulose carbon and new adsorbent-chitosan and its derivatives are widely used in industry. Through this method, it can be used to treat papermaking and printing and dyeing wastewater, urban domestic sewage, electroplating wastewater, fluorine-containing wastewater and so on.

4. ion exchange resin method: ion exchange resin is a kind of synthetic functional polymer material containing active groups, which can achieve purification by exchanging with special substances in sewage, and has the functions of exchange, selection, adsorption and catalysis. It is mainly used for recovering heavy metals and precious rare metals from industrial wastewater, purifying toxic substances and removing acidic or alkaline organic substances such as phenol, acid and amine from organic wastewater.

5. membrane separation technology: membrane separation technology is used to treat oily wastewater through ultrafiltration membrane, which can make the oil removal rate reach 97%-111%. It is mainly used for the treatment of various oily wastewater in industrial production, and can treat catering wastewater, pharmaceutical and chemical wastewater, dye wastewater and so on.