1. The size of the floc: If the floc is too small, it will affect the drainage speed. If the floc is too small, it will restrict more water and reduce the degree of mud cake. By selecting the molecular weight of polyacrylamide, the size of the flocs can be adjusted.

2. Characteristics of sludge. Firstly, it is important to understand the source, characteristics, composition, and proportion of sludge. According to their different properties, sludge can be divided into two types: organic and inorganic sludge. Cationic polyacrylamide is used for the disposal of organic sludge, while anionic polyacrylamide flocculants are used for inorganic sludge. When the alkalinity is strong, cationic polyacrylamide is used, while when the acidity is strong, anionic polyacrylamide is not suitable. When the solid content is high, the amount of polyacrylamide used in sludge is usually large.

3. Flocculation strength: Flocculation should remain stable and not break under shear. Improving the molecular weight of polyacrylamide or selecting appropriate molecular structures can help improve the stability of flocs.

4. Ionization Degree of Polyacrylamide: For dehydrated sludge, flocculants with different ionic degrees can be selected after a small trial to select the appropriate polyacrylamide. This can not only achieve good flocculant effect, but also reduce the dosage and save costs. 

5. The dissolution of polyacrylamide: Only when it is well dissolved can it fully exert its flocculation effect. Sometimes it is necessary to accelerate the dissolution rate, and at this time, one can consider increasing the concentration of polyacrylamide solution.