How to solve industrial waste water heavy metal exceed standard？
For heavy metals in wastewater, proper treatment must be carried out:
1) If conditions permit, try to reduce the amount of waste water, recycle its useful metals as much as possible, and recycle the waste water after proper treatment;
2) The sludge and concentrated liquid produced by the treatment, if there is no recycling value, should also be harmless treatment, so as to avoid twice pollution.
According to the properties of heavy metals in industrial wastewater, scientific and reasonable methods are adopted to separate and remove them, so as to improve the treatment level of industrial wastewater.
Commonly used for heavy metal treatment methods are mainly chemical precipitation method, which is divided into neutralization precipitation, sulfide precipitation, precipitation is more used by many people
01 Neutralization and precipitation method
Principle: By adding alkaline substances to wastewater, heavy metals can be removed by forming hydroxide precipitation with little solubility.
Although this method is relatively simple to operate and use, it also has the following shortcomings:
> high pH after treatment;
> unable to treat wastewater containing complex;
> Due to the formation of small particles of hydroxide in the process of heavy metal treatment, organic coagulant or inorganic flocculant should be added to precipitate.
02 Sulfide precipitation method
Principle: Adding sodium sulfide and other sulfide agents, so that the formation of heavy metal ions solubility product is very small heavy gold sulfide precipitation is removed.
This method mainly has the following characteristics:
> good dehydration performance, simple operation;
> but due to the instability of heavy metal sulfide, hydrogen sulfide gas will be produced in wastewater with lower pH.
> Heavy metal sulfide is easy to form colloidal shape, should not settle.
03 Reagent precipitation method
Principle: The method is mainly to add heavy metal trapping agent to the wastewater, one of the chemical products can chelate with heavy metal ions, the grafting synthesis process, the chelating group on the branch chain can form insoluble and precipitate with chelating heavy metals.
This method is popular among environmentalists because of the following advantages:
> not affected by the level of ion concentration;
> Wastewater containing complex components can be treated
> Wide range of use, suitable for any heavy metal ion complex salt, such as citric acid, tartaric acid, copper complex wastewater treatment.
