Wastewater treatment technology: what ion polyacrylamide is selected for electroplating wastewater treatment?
This kind of wastewater is generally strong acid water quality, the water quality is complex, the composition is not easy to control, which contains chromium, cadmium, nickel, copper, zinc, gold, silver and other heavy metal ions and cyanide, some of which are carcinogenic, teratogenic and mutagenic toxic substances.
When these heavy metals enter the water body, they have a magnifying effect on the food chain and can accumulate in some organs of the human body, causing chronic poisoning and endangering human health.
In the treatment of electroplating wastewater, because the wastewater contains many expensive heavy metals, if the heavy metals in the wastewater are recycled as a resource, it will not only solve the pollution of heavy metals, but also have certain economic benefits.
At present, the commonly used methods of heavy metal wastewater treatment include chemical precipitation, reduction, adsorption, membrane separation, coagulation, ion exchange, electrochemical method and so on. It is found that the selection of polyacrylamide for the treatment of this kind of wastewater is directly related to the pH value of the wastewater.
The best use method of polyacrylamide for electroplating wastewater and matters needing attention
1. The best model of polyacrylamide and the best dosage of the product were determined by small scale test.
2. The product is prepared into 0.1% (refers to solid content) of aqueous solution, and neutral water without salt is suitable.
3. When dissolving water, the product should be evenly sprinkled into the stirred water and heated properly (< 60 ℃) to form a solution.
4. Solid products are packed in polypropylene woven bags lined with plastic bags, 25kg each.
5. Solid products should not be scattered on the ground to prevent the ground from becoming slippery after absorbing moisture.
6. When preparing PAM aqueous solution, it should be carried out in enamel, galvanized, aluminum or plastic barrels, not in iron containers.
7. When dissolving, attention should be paid to adding the product evenly and slowly into the dissolver with stirring and heating measures. It should be avoided to solidify. The solution should be prepared at a suitable temperature. Excessive mechanical shear should be avoided for a long time. It is suggested that the agitator should be 60-200 rpm, otherwise it will lead to polymer degradation and affect the use effect.
When the majority of electroplating wastewater is in strong acid condition, we generally choose cationic coagulant, coagulate in alkaline condition, and select anionic polyacrylamide with ultra high molecular weight as coagulant aid.
What should be noted here is that due to the characteristics of electroplating wastewater itself, its pH value is relatively high. Before selecting reagents, it is better to select water samples for beaker test, and determine the type selection and dosage.
Generally, 20-100 kg of product is needed for every thousand tons of electroplating wastewater to be treated. The dosage of Polyacrylamide in the treatment of electroplating wastewater is about 2-10 G. The amount of polyacrylamide used in electroplating wastewater should be determined by considering the turbidity of wastewater, molecular weight of polyacrylamide and impurities in water.