1. Precautions for the use of cationic polyacrylamide
(1) Floc size: too small floc will affect the drainage speed, too large floc will restrict more water and reduce the mud biscuit degree. The molecular weight of polyacrylamide can adjust the size of floc.
(2) Sludge characteristics: the first point is to understand the source, characteristics and composition of sludge. According to different properties, sludge can be divided into organic and inorganic sludge. Cationic polyacrylamide is used to treat organic sludge, while anionic polyacrylamide is used to flocculate inorganic sludge. Anionic polyacrylamide is used when the alkalinity is strong, while anionic polyacrylamide is not suitable when the acidity is strong. When the solid content is high, the amount of polyacrylamide is usually large.
(3) Floc strength: floc should be stable without breaking under shear. Improving the molecular weight of polyacrylamide or selecting the appropriate molecular structure is helpful to improve the floc stability.
(4) Ionic degree of polyacrylamide: for dewatered sludge, flocculants with different ionic degrees can be used to select the best polyacrylamide after a small test, so as to obtain the best flocculant effect, minimize the dosage and save cost.
(5) Solubility of polyacrylamide: good dissolution can give full play to flocculation. Sometimes it is necessary to speed up the dissolving speed. At this time, it can be considered to improve the concentration of polyacrylamide solution.
2. The sequence method of adding polyacrylamide and other flocculants:
Pay attention to the sequence and interval of adding when using the composite flocculant. The combination of PAC and PAM is to make PAC neutralize charge / colloid to form fine flocs first, and then further increase floc volume is conducive to full precipitation. Due to the short reaction time of PAC, strong mixing is needed after adding, and PAM action time is long. Attention should be paid to mixing first strong and then weak - first strong is to mix evenly and then weak is to avoid damaging flocs. Polyacrylamide belongs to flocculant and polyaluminium chloride belongs to coagulant. Generally, coagulant is added first and then polyacrylamide is added. However, for the sake of safety, it is recommended that you determine the order of adding through the experimental results. The dosing point, dosage, dosing time and mixing intensity need to be determined by experiments. Remember not to use them together, otherwise it will affect the effect and increase the use cost.