1. The size of the flocs: too small flocs will affect the speed of drainage, too large flocs will restrict more water and reduce the degree of mud biscuit. After selecting the molecular weight of polyacrylamide, the size of the flocs can be adjusted.
2. Sludge characteristics: The first point is to understand the source, characteristics and composition of sludge, and its proportion. According to different properties, sludge can be divided into organic and inorganic sludge. Cationic polyacrylamide is used to dispose of organic sludge. The relative anionic polyacrylamide flocculant is used for inorganic sludge. Anionic polyacrylamide is used when the alkalinity is strong, and anionic polyacrylamide is not suitable when the acidity is strong. The solid content When the sludge is high, the amount of polyacrylamide is usually large.
3. Ionity of polyacrylamide: For dewatered sludge, flocculants of different ionicity can be selected through a small test first, and the most suitable polyacrylamide can be selected, so that the best flocculant effect can be obtained, and The dosage can be minimized and the cost can be saved.
4. The dissolution of polyacrylamide: the flocculation can be fully exerted only when the dissolution is good. Sometimes it is necessary to speed up the dissolution rate. At this time, consider increasing the concentration of the polyacrylamide solution.
In fact, in ordinary sewage treatment, some sewage cannot be achieved by using a single flocculant. It must be used in combination. The use of inorganic flocculant PAC and polyacrylamide composite flocculant will achieve better results. However, the order should be paid attention to when adding the medicine. If the order is not correct, the effect will not be achieved.
Polyacrylamide and other flocculants are mixed and used in the order of addition:
When using composite flocculants, you must pay attention to the order of addition and the time interval of dosing. The combined use of PAC and PAM is to let PAC complete the neutralization of charge/colloid destabilization to form fine flocs, and further increase the volume of flocs to facilitate full precipitation. Because the reaction time of polyaluminum chloride PAC is very short, it needs to be mixed strongly after adding. PAM has a longer action time. The mixing should be strong first and then weak-first strong is to mix uniformly and then weak to avoid damage to the flocs. Polyacrylamide is a flocculant, and polyaluminum chloride is a coagulant. Under normal circumstances, the coagulant is added first and then polyacrylamide. However, for the sake of safety, it is recommended that you determine the order of addition through experimental results. Dosing point, dosing amount, dosing time and mixing intensity need to be determined by experiment. Remember that you must not use the two drugs together, otherwise it will affect the effect and increase the cost of use.
Method for judging the failure of polyacrylamide flocculant:
We often encounter many sewage treatment plants, especially in the southern region. Due to the humid climate, the polyacrylamide in some sewage plants has been stacked for a long time or the packaging openings are not tight, resulting in moisture absorption and agglomeration. Aiming at the agglomeration of polyacrylamide flocculant Many people have doubts whether it is invalid or can it be reused. In fact, as long as you can dissolve it and the aqueous solution has viscosity, it will not fail, but the agglomerated polyacrylamide is difficult to dissolve. Opening it actually means a waste of resources. The shelf life of different types of polyacrylamide is very different. This is related to its structure. Relatively speaking, the shelf life of anionic polyacrylamide is longer. Cationic polyacrylamide generally has a shelf life of 1 year. Beyond this period, there is a risk of failure. The failure of polyacrylamide can be judged from two aspects, one is the decrease in viscosity, and the other is the deterioration of the flocculation effect. The storage environment has a great influence on the shelf life of polyacrylamide. If it is in a ventilated, dry and cool place, the shelf life of polyacrylamide can be extended. If it is in a high temperature and humid environment, the shelf life of polyacrylamide is relatively short.