The factors affecting the flocculation effect are various, mainly the type, concentration, dosage of flocculating agent, stirring condition during coagulation treatment, pH value, temperature and its changes, etc. Different countermeasures should be adopted according to the specific conditions.
1. Types and dosages of flocculants: Different flocculants should be used for different wastewaters. The amount of flocculant affects the flocculation effect to a large extent. Excessive and insufficient will lead to the dispersion and stability of the sol particles. Therefore, the optimum dosage should be determined through experiments.
2. Effect of stirring and reaction time: After a certain flocculant is added to the wastewater, the flocculant should be quickly and uniformly diffused into the water. After the flocculant is fully dissolved, the colloid produced in contact with the original colloid and suspended matter in the water will form a lot of tiny silk flowers, which is also called mixing. The mixing process requires intense turbulence in the water stream, allowing the agent to be thoroughly mixed with water in a relatively fast period of time, which typically takes a few seconds to two minutes.
3. The influence of PH value and alkalinity: The pH value has a great influence on the flocculant operation. Therefore, when the wastewater is flocculated, it is necessary to pay sufficient attention to the effective pH range. The limitation of PH value of organic polymer flocculant is not strict, but the low pH value has a great influence on the flocculation effect of flocculant. The inorganic flocculant is sensitive to the pH value of the wastewater. Since the hydrolysis reaction of the flocculant continuously generates hydrogen ions, it is necessary to keep the hydrolysis reaction sufficiently.
4. Influence of temperature: water temperature also has an effect on flocculation effect. The hydrolysis reaction of inorganic flocculant is endothermic reaction. When water temperature is low, it is not conducive to the hydrolysis of flocculant. The viscosity of water is also related to water temperature. If the water temperature is low, the viscosity of water is large. The Brownian motion of the water molecules is weakened, which is not conducive to the destabilization and flocculation of the colloidal contaminants in the water, and thus the formation of flocs is not easy. Therefore, the amount of flocculant used in winter is higher than in summer. The increase in temperature is conducive to the collision between the colloids, but the temperature exceeds 90 degrees Celsius, which makes the flocculant aging or decompose to produce insoluble matter, but reduces the flocculation effect.