How to reduce foaming in aeration tank？

In biological water treatment, microorganisms, including bacteria, fungi, algae, and protozoa, are used to oxidize and decompose harmful substances in water into harmless substances. Aeration is a crucial step in domestic water treatment, but a large amount of foam is often generated during the aeration stage. This foam cannot be eliminated naturally and requires chemical defoaming – adding a biological water treatment defoamer to the aeration tank.

The main reasons for foaming in aeration tank water treatment are:
Excessive aeration volume, unreasonable gas-to-water ratio, and oxygen supersaturation.
During wastewater treatment operation, a large number of filamentous bacteria and actinomycetes continuously grow in the water, easily generating a large amount of foam.
Excessively high concentration of organic matter in the influent and insufficient anaerobic retention time.
Too much foam during aeration or oxygen supply in biological water treatment affects the progress of water treatment or overflow, impacting the active sludge and bacteria.

Wastewater contains abundant surfactants and other additives.

Aeration tank defoamers are special defoamers used to control foam formation on the gas-liquid surface in the aeration tank. They possess strong defoaming capabilities, effectively destroying and inhibiting foam formation. The defoaming ability of aeration tank defoamers is mainly manifested in the following aspects:
Rapid Defoaming: Aeration tank defoamers can rapidly disrupt the structure of foam, causing it to disintegrate and dissipate. Once added to the aeration tank, they quickly contact the foam and diffuse to the foam surface, rapidly eliminating foam by reducing surface tension and disrupting the stability of the foam film.
Highly Effective Inhibition: Aeration tank defoamers not only eliminate existing foam but also effectively inhibit the formation of new foam. They form a protective layer in the aeration tank, reducing the surface tension at the gas-liquid interface, reducing bubble aggregation and foam stability, thereby preventing foam formation.

Durability: Aeration tank defoamers typically have long durability, maintaining their defoaming effect in the aeration tank for extended periods. They continuously interact with the foam and maintain the protective layer formed on the liquid surface, preventing foam reformation. 

High Temperature Resistance: The process conditions in aeration tanks are typically harsh, including high temperature and high humidity. Aeration tank defoamers usually possess good high temperature resistance, maintaining their defoaming ability even under high temperatures and are not easily affected by temperature-induced reduction in effectiveness.

Environmental Friendly: Most aeration tank defoamers are environmentally friendly and do not negatively impact water bodies and ecosystems. They are typically low in toxicity and readily biodegradable, meeting environmental protection requirements.