Abstract: This paper introduces a variety of commonly used plating metal wastewater treatment technology, and future trends of this technology.

Key words: electroplating; heavy metal waste water; treatment technology.

Electroplating wastewater treatment in general attention at home and abroad, developed a number of control technology, with the rapid development of electroplating industry, and increasing environmental requirements, at present, electroplating wastewater treatment has entered the clean production technology, total control and recycling economy integration phase.

A heavy metal status of wastewater treatment technology used.

(A) of the chemical method.

From electroplating wastewater treatment at home and abroad in recent decades, technological development trend, 80% of electroplating wastewater by chemical treatment, chemical treatment of wastewater, is the most widely used at home and abroad electroplating wastewater treatment technology, is much more mature chemical methods including precipitation, oxidation-reduction method, ferrite, etc., is a traditional and widely used method of treatment of electroplating wastewater, low investment, low processing cost, simple operation, applicable to all types of metal plating wastewater treatment, but the biggest chemical deficiencies, is the production of water can not be recycled, waste water and the large space occupied.

1. Chemical Precipitation.

Chemical precipitation is to the state of waste water was dissolved heavy metals into insoluble metal compounds of methods, including neutralization and sedimentation and sulfide precipitation, the method is a more mature and practical electroplating wastewater treatment, and treatment costs low, manageable, treated wastewater meeting the emission standard.

(1) and precipitation in the waste water containing heavy metals and adding alkali to the reaction to produce insoluble metal hydroxide precipitate forms to be separated and sedimentation method is simple and is commonly used wastewater treatment method.

(2) sulfide precipitation by adding sulfide to heavy metals in waste water generated sulfide precipitate and remove the method, compared with the precipitation and sulfide precipitation method has the advantage of: heavy metal sulfide solubility than its hydroxide lower solubility, the reaction between PH value 7-9, treated wastewater and in general do not have to deal better, but the disadvantage of sulfide precipitation are: sulfide precipitation particles is small, easy to form a gel, sulfide precipitation residue in water, with acids generated gas, may cause secondary pollution.

2. Oxidation-reduction.

Adding reducing agent to the waste water will be reduced to micro-high heavy metal heavy metal ions toxicity of low-cost, and then to remove the alkali into the precipitation and separation methods, the method is simple, operation is easy to grasp, but there is poor water quality treatment can not reuse, mixed waste water treatment, could easily lead to secondary pollution, and general supplies and toxic oxidants are issues to be resolved.

3. Ferrite.

Ferrite Ferrite is based on the principles developed in the production approach, the treatment of heavy metal waste water, to a removal of various metal ions, especially for one-time mixed-metal plating wastewater treatment, with simple equipment, low investment , easy to operate, while the formation of the sludge has high chemical stability, easy to micro-separation and dehydration treatment, the electroplating industry in the application of wider domestic, but in the formation of ferrite in the course of heating (about 70 ), high energy consumption, there is high salinity treatment, but can not handle complex wastewater containing Hg and shortcomings.

(B) evaporation method.

Evaporation method is electroplating waste water evaporation, so that can concentrate heavy metals in wastewater and recycling of way, the generally applicable to the handling of chromium, copper, silver, nickel and other heavy metals in wastewater containing low concentrations of heavy metals in wastewater direct application of vaporization of law energy consumption, high cost and Wastewater Treatment evaporation and other methods and is generally used, such as the evaporator pressure and current wash system in combination treatment of electroplating wastewater, enabling closed loop, a good effect, evaporation of metal plating wastewater treatment, process maturity is simple, does not require chemical reagents, no secondary pollution, can be reused water or valuable metals, good environmental and economic benefits, but energy consumption, high operating costs, impurity recycling problems still to be studied, so that application is limited, at present, generally as a means of other methods of secondary treatment.

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