Cautions for Cationic Polyacrylamide Use

Cautions for Cationic Polyacrylamide Use
1. Floc size: Too small flocs impair drainage speed while excessively large ones decrease dry density of the sludge cake. The molecular weight of polyacrylamide can be adjusted to modify floc size.

2. Sludge properties: Understand the origin, characteristics, and composition of the sludge, its proportion. Depending on their nature, sludge can be divided into organic and inorganic types. Cationic polyacrylamide is used for organic sludge, while anionic polyacrylamide flocculant is used for inorganic sludge. Anionic polyacrylamide is suitable for highly alkaline conditions, but not acidic ones, and high solid content usually requires more polyacrylamide.

3. Floc strength: The floc should remain stable under shearing without breaking. Enhancing the molecular weight of polyacrylamide or selecting the appropriate molecular structure can improve floc stability.

4. Polyacrylamide's ionicity: For dewatered sludge, different ionicity flocculants can be selected through a preliminary test to determine the optimal polyacrylamide, which will yield the best flocculant effect and minimize the amount of additive, saving costs.

5. Polyacrylamide dissolution: Optimal flocculation requires good dissolution. Sometimes, faster dissolution is needed, which can be achieved by increasing the concentration of polyacrylamide solution.

In actual wastewater treatment, some wastewater cannot be effectively treated with a single flocculant; it must be combined with two. Combining PAC, an inorganic flocculant, with polyacrylamide, a composite flocculant, yields better results in wastewater treatment. However, the order of adding the chemicals must be considered, as incorrect order can also lead to ineffective results.