The use of a large number of heavy metal wastewater, acid and alkali metal solution in the production process, including cadmium and cyanide, acid and other toxic and harmful chemicals in the process of emission of environmental pollution and harm to human health, waste gas and waste residue, has become a heavy pollution industry.

In the treatment of heavy metals in wastewater, the common methods can not be broken down, but can only be transferred to its location and change its physical and chemical forms. Namely: treatment by sedimentation after chemical reduction, heavy metals in wastewater from ion dissolved into insoluble compounds precipitated from water, transferred into sludge, then through ion exchange treatment, exists in the regeneration fluid. In a word, two kinds of products are formed after the treatment of heavy metal wastewater, one is the removal of heavy metals from the treated water, and the other is the concentration of heavy metals, the sludge. The treated water can be discharged if the concentration of heavy metal is less than the discharge standard. Most of the heavy metals in the concentrated product have the use value, as far as possible recycling, no recycling value, to be harmless treatment.