Polyaluminium chloride can be divided into two types in terms of form: solid and liquid. Solids can be divided into brown, yellow and white according to their colors. Polyaluminium chloride of different colors also has great differences in application and technology. The structure of polyaluminium chloride is composed of multi-element complexes with various forms. It has a fast flocculation and sedimentation speed and is applicable to a wide range of pH values. The floating of (PAC) flocs will affect the sewage treatment effect. The following are some measures to prevent the floating of PAC flocs:
Optimize PAC dosage and dosage method
Determine the appropriate dosage: accurately determine the optimal dosage of PAC for specific water quality through methods such as beaker test. Too little dosage will result in poor flocculation effect; too much dosage may cause the colloid to stabilize again, the flocs to become smaller and difficult to settle, and then float.
Use a reasonable dosage method: prepare PAC into a solution of appropriate concentration, and adopt a continuous and uniform dosage method to avoid local excessive dosage.At the same time, according to the water flow characteristics and mixing conditions of the reaction tank, select a suitable dosage point to ensure that PAC and sewage are fully and evenly mixed.
Control water quality conditions
Adjust pH value: PAC has different flocculation effects in different pH ranges. Generally speaking, its suitable pH range is between 6 and 9. By adding acid-base regulators, the pH value of sewage can be controlled within this range, which helps to form larger, dense flocs with good sedimentation performance and reduce the possibility of flocs floating.
Reduce the concentration of suspended particles in water: Too high a concentration of suspended particles in the influent will affect the flocculation effect and increase the risk of flocs floating. In the pretreatment stage, sedimentation, filtration and other methods can be used to reduce the content of suspended particles in the water, creating good conditions for subsequent flocculation and sedimentation.
Control water temperature: Water temperature also has a certain effect on the flocculation effect of PAC. When the water temperature is too low, the flocculation reaction slows down, the flocs are formed slowly and the structure is loose, and it is easy to float; when the water temperature is too high, the PAC hydrolysis rate may be too fast and the flocs are small. Generally speaking, it is more appropriate to control the water temperature at 20-30℃.
Improve reaction conditions
Provide a good mixing and reaction environment: During the flocculation reaction process, it is necessary to provide appropriate stirring intensity and reaction time. In the initial mixing stage, PAC and sewage should be mixed quickly and fully to promote the contact and adsorption of flocculants and colloidal particles; in the flocculation reaction stage, the stirring intensity should be gradually reduced to avoid the flocs from being broken, while ensuring sufficient reaction time so that the flocs can fully grow and settle.
Set up a reasonable reaction tank structure: The structural design of the reaction tank should be conducive to the sedimentation of flocs. For example, the use of a plug-flow reaction tank can reduce the short-circuit and back-mixing of the water flow, so that the sewage and flocculants have a more uniform residence time and reaction conditions in the tank; in the design of the sedimentation tank, the position and form of the water inlet, outlet and sludge outlet should be reasonably set to avoid the disturbance of the water flow to the flocs and ensure that the flocs can settle smoothly to the bottom of the tank.
Strengthen sludge management
Timely sludge discharge: If the sludge at the bottom of the sedimentation tank is not discharged in time, it will gradually accumulate and undergo anaerobic fermentation, produce gas, and cause the sludge to float, thereby driving the flocs to float. Therefore, according to the accumulation of sludge, a reasonable sludge discharge plan should be formulated to discharge sludge regularly and timely to maintain the stability of the sludge amount in the sedimentation tank.
Prevent sludge swelling: Sludge swelling will lead to loose sludge structure, poor sedimentation performance, and easy to cause flocs to float. Prevent sludge swelling by controlling parameters such as nutrient balance, dissolved oxygen content, and sludge load in sewage. For example, ensure that the proportion of nutrients such as carbon, nitrogen, and phosphorus in sewage is appropriate to avoid the lack of nutrients such as nitrogen and phosphorus; control the dissolved oxygen in the aeration tank within a suitable range, generally 2-4mg/L; reasonably adjust the sludge load to avoid being too high or too low.
The main products of flocculant manufacturer Xinhuan Water Treatment are:
White polyaluminium chloride (food grade), drinking grade polyaluminium chloride, industrial grade polyaluminium chloride, anionic polyacrylamide, cationic polyacrylamide, nonionic polyacrylamide, petroleum recycling polyacrylamide, oil recovery polyacrylamide, polyacrylamide, polymer flocculant polymer flocculation coagulant, polymeric ferrous sulphate, polyferric aluminium chloride and other water treatment chemicals. Welcome customers to write to us to negotiate business! Tel/WhatsApp：+8619003830067 Email：joanna@xhwtm.com Contact:Joanna
