Progress in the treatment of copper(II)-containing wastewater and wastewater treatment systems based on combined technologies: A review

The widespread use of copper in various industries leads to a wide range of copper-containing wastewater (CCW) sources, which cause varying degrees of damage to humans, animals, plants, and the environment. To realize sustainable societal development, the treatment of wastewater before discharge is very important. By searching for as many articles as possible about CCW in recent years and synthesizing the contained information, this paper reviews conventional treatment methods for CCW, including chemical methods (chemical precipitation, replacement, flotation, and electrolysis) and physicochemical methods (membrane treatment, ion exchange, adsorption, and solvent extraction). The concepts/mechanisms relevant to these treatment methods, as well as the applications, advances, advantages and disadvantages of each technology, are summarized, and methods of improving each processing technique are summarized in the corresponding section. After improvement, most of these technologies can achieve better wastewater treatment results. Then, the main factors influencing the effectiveness of each process are summarized. However, single treatment technologies often have problems such as high energy consumption, secondary pollution, and a poor treatment effect when treating real wastewater. Existing articles have reported that the combination of various treatment units to form wastewater treatment systems has advantages: environmental friendliness, low cost, good copper recovery, almost complete removal of copper in wastewater, and a lower effluent Cu2+ concentration. Finally, this paper discusses six kinds of combined technologies for the treatment of CCW. The advantages of combined technologies compared with single treatment technologies suggest that the development of CCW treatment from single to diversified combined treatment modes is an inevitable trend and has strong significance and development prospects.