The current status of heavy metal pollution and treatment technology development in China

Heavy metal pollution has become a serious environmental problem and received increasing attention in recent years in China. In this paper, the current status of heavy metal pollution is analysed; the major heavy metal pollutants include Hg, Cd, Cr(VI), Pb and As. Non-ferrous metal industries, including mining and smelting, discharge about 67.8% of the total amounts of these five metals. Electroplating wastewater mainly from metal products manufacture and the printed circuit board industry also contributed to serious heavy metal pollution. For the discharge amount of Hg, Cd, Cr(VI), Pb and As, Chinese western and central area accounted for about 87%. Heavy metal-containing wastewater varied greatly quantitatively and qualitatively. Different treatment technologies for heavy metal removal from wastewater are introduced, evaluated and compared, including ion exchange, adsorption, solvent extraction, evaporation, air flotation, chemical precipitation, chemical oxidation and reduction, electrolyzation, biological flocculation, biosorption, membrane separation and nanotechnology. It is difficult to treat such complex wastewater using any single treatment method alone to meet the discharge standard. Integrated treatment processes should be applied. To alleviate and eliminate heavy metal pollution in China, comprehensive consideration should be taken to improve wastewater reuse, heavy metal recovery and the suitable disposal of the resulted residual wastes containing heavy metals. Multidisciplinary collaboration is required to develop innovative technologies for heavy metal wastewater treatment.