In the chemical process of removing heavy metal components, coagulants, coagulants, flocculants, heavy metal removers, caustic soda, sulfuric acid and other agents are used
Heavy metal wastewater mainly comes from wastewater discharged from enterprises such as mines, smelting, electrolysis, electroplating, pesticides, medicines, paints, and pigments. If the heavy metal wastewater is not treated, it will seriously pollute the environment. The type, content and existing form of heavy metals in wastewater treatment vary with different manufacturers. Removal of heavy metals is very important in wastewater treatment.
Because heavy metals cannot be decomposed and destroyed, they can only transfer their location and change their physical and chemical forms to achieve the purpose of removing heavy metals. For example, in the process of wastewater treatment, after chemical precipitation treatment, the heavy metals in the wastewater change from dissolved ionic forms to insoluble compounds and precipitate and transfer from the water to the sludge; after ion exchange treatment, the heavy metals in the wastewater The heavy metal ions are transferred to the ion exchange resin, and after regeneration, they are transferred from the ion exchange resin to the regeneration waste liquid.
Therefore, the principle of removing heavy metals in wastewater treatment is:
Principle 1: The most fundamental thing is to reform the production process. Do not use or use less toxic heavy metals;
Principle 2: Adopt reasonable technological process, scientific management and operation, reduce the amount of heavy metals and the amount of waste water lost, and minimize the amount of discharged waste water. The treatment of heavy metal wastewater should be treated on-site at the place of production, and mixed with other wastewater to avoid complicating the treatment. Moreover, it should not be discharged directly into urban sewers without heavy metal removal, so as not to expand heavy metal pollution.
The methods for removing heavy metals in wastewater treatment can generally be divided into two categories:
Method 1: The heavy metals in the wastewater are transformed into insoluble metal compounds or elements, which are removed from the wastewater by precipitation and floating. Applicable methods such as neutralization precipitation method, sulfide precipitation method, floating separation method, electrolytic precipitation (or floating) method, diaphragm electrolysis and other wastewater treatment methods;
Method 2: Concentrate and separate the heavy metals in the wastewater without changing their chemical form. Applicable methods include reverse osmosis, electrodialysis, evaporation, and ion exchange. These wastewater treatment methods should be used alone or in combination according to the quality and quantity of wastewater.