Key points for selecting defoamer for sewage treatment
Sewage treatment requires special additives to enable sewage to meet discharge standards as soon as possible. Eliminating foam is one of the tasks. So what are the key points for selecting sewage treatment defoamers? Here is an introduction for everyone:
1. Insoluble or difficult to dissolve in the foaming liquid
To break the foam, the sewage treatment defoamer should be concentrated and concentrated on the bubble film. For the case of the defoamer, it should be concentrated and concentrated in an instant, and for the case of the foam suppressant, it should always be kept in this state. Therefore, the sewage treatment defoamer is in a supersaturated state in the foaming liquid, and only insoluble or difficult to dissolve can it easily reach a supersaturated state. Insoluble or difficult to dissolve, it is easy to gather at the gas-liquid interface, easy to concentrate on the bubble film, and can play a role at a lower concentration. For sewage treatment defoamers used in water systems, the molecules of the active ingredients must be strongly hydrophobic and weakly hydrophilic, and the HLB value must be in the range of 1.5-3 for the best effect.
2. The surface tension is lower than that of the foaming liquid.
Only when the intermolecular force of the sewage treatment defoamer is small and the surface tension is lower than that of the foaming liquid, can the sewage treatment defoamer particles be immersed and expanded on the bubble film. It is worth noting that the surface tension of the foaming liquid is not the surface tension of the solution, but the surface tension of the foaming solution.
3. Have a certain degree of affinity with the foaming liquid.
Since the defoaming process is actually a competition between the foam collapse speed and the foam generation speed, the sewage treatment defoamer must be able to disperse quickly in the foaming liquid so that it can quickly play a role in a wider range of the foaming liquid. In order to make the sewage treatment defoamer diffuse faster, the active ingredients of the sewage treatment defoamer must have a certain degree of affinity with the foaming liquid. If the active ingredients of the sewage treatment defoamer are too close to the foaming liquid, they will dissolve; if they are too sparse, they will be difficult to disperse. Only when the affinity is appropriate, the effect will be good.
4. No chemical reaction with the foaming liquid.
When the sewage treatment defoamer reacts with the foaming liquid, on the one hand, the sewage treatment defoamer will lose its effect, and on the other hand, harmful substances may be produced, affecting the growth of microorganisms.
