What are the commonly used flocculants?

1, polyaluminum chloride (PAC): It can achieve good flocculation effect on all kinds of wastewater, quickly form large alum flower, has good sedimentation performance, and is suitable for a wide range of pH values (pH is between 5 and 9), and the pH value and alkalinity of treated water are slightly decreased. When the water temperature is low, it can still maintain a stable flocculation effect, and its alkalinity is higher than other aluminum salts and iron salts, so the liquid medicine has less corrosion to the equipment.

2. Polyferric sulfate (PFS): coagulation is fast, concentrated, heavy and fast. Especially for low-temperature and low-turbidity water, it has excellent treatment effect, is suitable for the pH range of water (pH is between 4- 1 1), and has little corrosiveness. Experiments show that purifying water with polymeric iron can reduce the content of nitrite nitrogen and iron. Therefore, it is an excellent and safe coagulant for drinking water and is expected to replace polyaluminum coagulant harmful to human body.

3. Poly-iron: High-valence metal ions can be reduced to low-valence metal ions without acidification. Coagulant has dual functions of charge neutralization and adsorption bridging in water. When used in combination with activator * * *, colloidal substances can be transformed into coagulation, and metal ions such as copper, zinc and nickel in wastewater can be removed at the same time. It is an efficient purifying agent for electroplating wastewater.

4. Polyaluminum sulfate (PAS): The turbidity removal effect is remarkable, and it has a wide range of application for raw water temperature. It can not only treat industrial water, but also treat industrial wastewater.

5. Polysilicic acid (PS): At present, the preparation method, polymerization mechanism and influencing factors of polymerization degree of polysilicic acid have been deeply studied. It is found that the polymerization rate can be controlled by neutralizing the difference of pH value. Polysilicic acid has strong bonding aggregation ability and adsorption bridging effect.

6. Polyacrylamide: Polyacrylamide is the most widely used organic polymer flocculant. There are three types of polyacrylamide: nonionic, cationic and anionic. Their molecular weight is between 500,000 and 6 million.

Because this flocculant has a certain amount of residual monomer acrylamide, it inevitably brings toxicity. High molecular weight sodium polyacrylate (above 106) is an anionic coagulant with strong coagulation effect and no toxicity. Sodium polyacrylate produces nonionic adsorption on fine particles suspended in water medium, which leads to cross-linking between particles. It shows excellent performance for positively charged colloidal particles such as metal hydroxide.

7. Poly (dimethyl diallyl ammonium chloride): cationic polymer compound, which can achieve better treatment effect than inorganic polymer flocculant and organic polymer coagulant polyacrylamide commonly used at present, can be used alone or in combination with inorganic coagulant.

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