1. The flocculant in sewage treatment often refers to polyacrylamide (PAM), which is a water-soluble high molecular polymer, insoluble in most organic solvents, has good flocculation, and can reduce the friction resistance between liquids.
2. PAM can be divided into three types: anionic polyacrylamide, cationic polyacrylamide, and nonionic polyacrylamide.
2.1.1 Anionic type: high turbidity wastewater (sand washing, mining wastewater);
2.1.2 Cationic type: sludge dehydration (municipal sewage);
2.1.3 Nonionic type: acidic or metal ion-containing wastewater.
3. Principle: When the aqueous solution is added to the wastewater, a compressed double layer will be generated, causing the suspended particles in the wastewater to lose stability, and the colloidal particles will condense with each other to increase the size of the particles, forming floccules and alum flowers. When the floccules grow to a certain volume, they will separate from the water phase under the action of gravity and precipitate, thereby removing a large amount of suspended matter in the wastewater, thereby achieving the effect of water treatment.
4. Usage and precautions
4.1 Pay attention to the storage conditions of polyacrylamide. Polyacrylamide should be stored in a dry, cool, and well-ventilated place, avoiding direct sunlight and high-temperature environments. Additionally, ensure that the packaging is intact to prevent moisture absorption and contamination by impurities.
4.2 When using polyacrylamide, choose the correct model and dosage. Different models of polyacrylamide have different characteristics and applications, and the appropriate model should be selected based on the characteristics and processing requirements of the target material. The dosage should also be adjusted according to specific conditions to achieve the best treatment effect.
4.3 When dissolving polyacrylamide, pay attention to the operating methods and dissolution conditions. Polyacrylamide should be dissolved in water at room temperature, avoiding the use of excessively hot water to prevent impacts on its dissolution effects and performance. Also, clean containers and tools should be used during dissolution to avoid contamination.
4.4 Safety precautions should be observed when using polyacrylamide. During operation, appropriate protective gear, such as gloves and masks, should be worn to avoid skin contact and inhalation of dust. If accidental contact or inhalation occurs, rinse immediately with plenty of water or seek medical attention.
4.5 After using polyacrylamide, proper disposal of waste is necessary. Discarded polyacrylamide solutions and packaging materials should be classified and disposed of according to relevant regulations to avoid environmental pollution.
5. Characteristics
5.1 Flocculation: PAM can make suspended matter flocculate through electrical neutralization, bridging adsorption.
5.2 Adhesion: It can act as an adhesive through mechanical, physical and chemical effects.
5.3 Resistance reduction: PAM can effectively reduce the friction resistance of the fluid. Adding a trace of PAM to water can reduce resistance by 50-80%.
5.4 Thickening: PAM has a thickening effect under neutral and acid conditions. When the pH value is above 10, PAM is easily hydrolyzed. When it is a semi-net structure, the thickening will be more obvious.
6. Usage
6.1 The flocculants used for desludging of domestic sewage are different according to different treatment methods. When PAM is used as a sludge dewatering agent, the ratio with water is generally between 0.1%-0.2%.
6.2 In industrial wastewater, the amount of cationic polyacrylamide used for coal washing can be set between 30 kilograms and 110 kilograms; the amount of wastewater used in the chemical industry is generally between 50 and 120 kilograms; the wastewater from the bleaching and dyeing industry and the wastewater from the papermaking industry are the most difficult to treat, and the amount used should be increased. It is more reasonable to set the amount used between 100 and 300 kilograms. The electroplating wastewater industry and ordinary industrial water use generally should not exceed 50 kilograms.
