Polyacrylamide is used as a flocculant in many cases. Do you know the role of polyacrylamide used as a flocculant

1. Coagulation stage: when we add liquid (flocculant or polyaluminum chloride), it is a process of injecting liquid into the coagulation pool and condensing raw water in a short time to form fine alum flower. At this time, the water body becomes turbid and strong turbulence is required. In the beaker experiment, it is recommended to stir (250-300rpm) for 10-30 seconds, usually no more than 2 minutes. The effect is good at this time

2. Flocculation stage: it is the process of alum growth and coarsening, which requires appropriate turbulence and sufficient residence time (10-15 minutes). It can be observed that a large amount of alum slowly sinks in the later stage, forming a transparent layer on the surface. The beaker experiment was first stirred at 150 rpm for about 6 minutes, and then stirred at 60 rpm for about 4 minutes until it was suspended. Look at its reaction. If the effect is ignored, adjust it in time

3. Sedimentation stage: for the treatment of domestic sewage and wastewater, the product shows positive charge in compatible or alkaline medium, so that the negative charge of suspended particles in the sewage is used to flocculate and settle the sewage. This is a process of settling flocs in the sedimentation tank, which requires slow water flow. Inclined tube (plate) sedimentation tank (separation of flocs by air floatation) is usually used. A large number of rough alum flowers are blocked by the inclined tube (plate) wall and deposited at the bottom of the sink. The water in the upper layer is clear water. The remaining alum flowers with small particle size and small density continue to collide with each other and form a large knot until the remaining turbidity remains basically unchanged