Application of polyacrylamide in wastewater treatment process

 

Chemical precipitation

Zinc is a kind of amphoteric element, its hydroxide is insoluble in water, and has weak alkalinity and weak acidity, so its chemical formula can be written as: basic :Zn(OH)2, acid :H2ZnO2.

Coagulation precipitation method

The principle of coagulation precipitation method is to add coagulant (lime, ferric salt, aluminum salt) into the wastewater containing zinc, and form hydroxide flocculant under the weakly alkaline condition of pH=8 ~ 10, which has flocculation effect on zinc ion and co-precipitation precipitation.

Sulfide precipitation process

Sulfide precipitation method takes advantage of the strong affinity between Na2S and S2+ in MgS and heavy metal ions under weak alkaline conditions to generate sulfide precipitation with small positive solubility and remove it from the solution.

Ferrite method

Ferrite is an oxide solid solution composed of iron ions and other metal ions, a process originally developed by NEC.

Electrolytic process

Electrolysis method is to use the electrochemical properties of metal, under the action of direct current, zinc (II) compounds are dissociated into metal ions at the anode, reduced into metal at the cathode, and remove the zinc ions in the waste water. This method is an effective method to treat wastewater containing high concentration of zinc, with high treatment efficiency and easy to recycle. But the disadvantage of this method is that the concentration of zinc ions in the water can not be lowered very low. Therefore, electrolysis method is not suitable for treating zinc containing wastewater with low concentration, and this method has high power consumption and high investment cost.

Ion exchange method

The ion exchange method is carried out in an ion exchanger with the help of an ion exchanger. 7 adsorption method adsorption method is the application of porous adsorption material adsorption treatment of zinc containing wastewater a method, the traditional adsorbent is activated carbon. Recommended selection of Baike brand coal sewage treatment activated carbon.

 

Usage of polyacrylamide PAM and matters needing attention

 

1. Determine the best model and the best dosage of the product through small test.

 

2, the product is prepared into 0.1% (solid content) concentration of aqueous solution, neutral water without salt is appropriate.

 

3. When dissolving water, evenly sprinkle the product into stirred water and increase temperature appropriately (<60℃) to accelerate into solution.

 

4, solid products are packed in polypropylene woven bags, lined with plastic bags, each bag 25kg, plastic body packed in plastic barrels, lined with plastic bags, each 50kg or 200kg.

 

5, this product has hygroscopic, should be sealed in a cool and dry place, the temperature should be below 35℃.

 

6, solid products to avoid sprinkle on the ground, in order to prevent the product moisture after slippery.

 

7, preparation of PAM aqueous solution, should be carried out in enamel, galvanized, aluminum or plastic bucket, not in iron container preparation and storage.

 

8. When dissolving, attention should be paid to adding the product evenly and slowly into the dissolver with stirring and heating measures. Consolidation should be avoided. Recommended agitator 60-200 RPM /min, otherwise it will lead to polymer degradation, affect the use effect.

 

9, PAM aqueous solution should be used now, when the solution is placed for a long time, its performance will gradually reduce depending on the water quality.

 

10, after adding flocculant aqueous solution to the suspension, if stirred for a long time and intensely, it will destroy the anionic polyacrylamide (APAM) that has been formed. Anionic polyacrylamide (APAM) is white powder in appearance, with molecular weight from 6 million to 25 million water solubility, can be dissolved in any proportion in water and insoluble in organic solvents. The effective PH range is 7 to 14. It is highly polymer electrolyte in neutral alkaline media and is sensitive to saline electrolytes and can cross-link with high-priced metal ions to form insoluble colloids.

 

Anionic polyacrylamide (APAM) product characteristics

 

1) flocculation: PAM can make suspended substances through electric neutralization, bridging adsorption, flocculation.

 

2) bonding: through mechanical, physical and chemical effects, the bonding effect.

 

3) resistance reduction: PAM can effectively reduce the frictional resistance of fluid, adding trace PAM in water can reduce the resistance by 50-80%.

 

4) thickening: PAM has thickening effect under neutral and acidic conditions. When PH value is above 10, PAM is easy to hydrolysis and presents a semi-reticular structure, the thickening will be more obvious.

 

Anionic polyacrylamide (APAM) is mainly used

Industrial wastewater treatment: for suspended particles, relatively high concentration, particles with positive charge, PH value of water neutral or alkaline sewage, iron and steel plant wastewater, electroplating plant wastewater, metallurgical wastewater, coal washing wastewater and other sewage treatment, the best effect. Drinking water treatment: The water source of many waterworks in China comes from rivers, with high sediment and mineral content and turbidity. Although filtered by precipitation, it still cannot meet the requirements. Flocculant needs to be added, and the dosage is 1/50 of inorganic flocculant, but the effect is several times that of inorganic flocculant. For serious organic pollution of river water can be used inorganic flocculant and my company's cationic polyacrylamide with better effect. Starch factory and a loss of alcohol plant starch grains recycling: now a lot of a lot of waste water containing starch starch factory, now adding the anionic polyacrylamide, the starch particles flocculation precipitation, and then to pass through the filter press filter sediment into the pie, as feed, alcohol plant also can be used anionic polyacrylamide dehydration of alcohol, filter for recycling. Used for mud settlement in river water. Used as dry strength agent in paper making.

Used for papermaking auxiliaries and rate AIDS. Adding trace AMOUNT of PAM-ASG-3 anionic polyacrylamide into the pump storage tank before paper making can increase the retention of water filler and fine fiber on the net by 20-30%. Each ton can save pulp 20-30kg.