There are many methods for treating electroplating wastewater, which can be divided into four categories based on their working principles: physical method, chemical method, physicochemical method, and biological method.

(1) Physical method

Physical method is the use of physical interactions to separate pollutants that are mainly suspended in wastewater, without changing the chemical properties of the substances during the treatment process, such as oil removal, evaporation concentration, and reuse of water in electroplating wastewater. In the process of treating electroplating wastewater, the main commonly used methods are electrodialysis, reverse osmosis, ultrafiltration, and adsorption. Generally, physical methods are only used as a part of their treatment methods and are rarely used alone.

(2) Chemical method

The chemical method refers to the addition of some chemical agents to wastewater, which changes the chemical properties of pollutants in the wastewater through chemical reactions, making them harmless substances or substances that are easy to separate from water, and then further removing them from the wastewater. Currently, chemical methods are widely used in the treatment of electroplating wastewater. According to reports, approximately 41% of electroplating plants in China use chemical methods to treat electroplating wastewater; In Japan, chemical methods account for about 85% of the total governance. This method has the advantages of simple and reliable operation, low investment, being able to withstand large amounts of water and high concentration loads, and stable effects. It is suitable for wastewater treatment of various types of electroplating enterprises. However, there is also a problem of secondary pollution of electroplating sludge, and enterprises generally entrust qualified units to dispose of it.

(3) Physical and chemical methods

Physicochemical method refers to the purification of wastewater through the combined action of physics and chemistry. The electrolysis method and ion exchange method are commonly used, both of which can achieve heavy metal recovery and have good effluent quality. However, the equipment and operation costs are relatively high, and there are certain limitations in promotion. They are usually used in combination with other processes.

(4) Biological method

The biological method for treating electroplating wastewater mainly utilizes the life activities of microorganisms to transfer and transform pollutants in the wastewater, thereby purifying the wastewater. Biological treatment of electroplating wastewater is a promising technology, which is easily accepted by factories in terms of process flow and operational control. If biologists can further improve functional bacteria, achieve rapid reaction and high-speed reproduction.