What are the solutions for sewage foam?

In the process of sewage treatment, a large amount of foam is often encountered, which will overflow from the pool and cause serious pollution of the external pool wall of external equipment. So how to deal with foam in wastewater treatment?

3 forms of foam

1. Start the bubble

In the initial stage of the activated sludge process operation, surface foam is easily caused due to the presence of some surface active substances in the sewage. However, as the activated sludge matures, these surface active substances are degraded by microorganisms, and the foaming phenomenon will gradually disappear.

2. Denitrification foam

If the sewage treatment plant carries out the nitrification reaction, denitrification will occur in the sedimentation tank or in places where aeration is insufficient, and nitrogen and other bubbles will be generated, which will drive part of the sludge to float, and foaming will occur.

3. Biofoam

Due to the abnormal growth of filamentous microorganisms, the foam mixed with air bubbles and floc particles is stable, continuous and difficult to control.

Biofoam is very unfavorable to the normal operation of the sewage plant. A large number of filamentous microorganisms appear in the aeration tank or secondary sedimentation tank, floating on the water surface and accumulating a large amount of foam, causing the concentration of effluent organic matter and suspended solids to increase, resulting in odor or odor. Bad and harmful gases reduce the oxygen transfer efficiency of mechanical aeration, which may cause a large amount of surface foam during the later sludge digestion.

Solution

1. Spray water

This is one of the most commonly used physical methods. Reduce foam by spraying water or beading to break up air bubbles floating on the surface. The scattered sludge particles partially recovered the sedimentation performance, but the filamentous bacteria still existed in the mixed liquid, so the foaming phenomenon could not be fundamentally eliminated.

2. Add defoamer

The chemical agent developed for the removal of sewage foam is mainly composed of polyether with strong foam suppression ability and dimethyl silicone oil with strong hydrophobicity and rapid foam breaking. It has both the functions of foam suppression and defoaming.

3. Reduce sludge age

It is generally used to reduce the residence time of sludge in the aeration tank to inhibit the growth of actinomycetes with a longer growth period.