Defoamers & Antifoam Agents

Defoamer or antifoam: what is the difference?

The two words are often used for the same products. Strictly, a defoamer breaks foam that has already formed, while an antifoam is added beforehand to stop foam from forming. Most industrial products do both. They work by spreading quickly across the thin walls of foam bubbles, weakening them so the bubbles burst and the trapped air escapes.

Types of defoamer and where they fit

Why does foam form in treatment plants?

• Detergents and surfactants from homes, laundries, kitchens and industrial washing.
• Start-up or overload of the biological process, which produces white, billowing foam.
• Filamentous bacteria such as Nocardia, which produce thick brown, stable foam.
• Proteins, starches and fats from food, dairy and paper effluent.
• High aeration that whips these substances into foam.

A defoamer gives quick relief, but if foam keeps returning it is worth finding the cause, for example sludge age, oxygen levels or a surfactant discharge.

How to dose a defoamer

1. Dose where the foam forms, usually by drip or spray onto the foam surface or into the inlet of the aeration tank.
2. Start with a small dose and increase until foam is controlled. More is not better.
3. Dilute if the product allows, so it spreads evenly. Follow the product guidance.
4. Check the effect on the process, such as oxygen transfer, filter performance or coatings.

Overdosing defoamer can reduce oxygen transfer in aeration tanks, leave residues and waste money. Use the smallest dose that keeps foam under control.

Industries we supply

• Sewage and effluent treatment
• Textile dyeing and processing
• Paper and pulp
• Food processing and dairy
• Fermentation, distilleries and breweries
• Paints, coatings and adhesives
• Detergents and cleaning products
• Cooling towers
• Construction chemicals
• Agrochemicals

Defoamers & Antifoam: product range

Each product line has its own page with uses, dosing guidance and FAQs.

• Silicone Defoamer
• Silicone-Free Defoamer

Frequently asked questions

What is a defoamer?

A defoamer is a chemical that breaks foam and stops it from re-forming. It spreads across foam bubbles and weakens their walls so the bubbles burst.

What is the difference between a defoamer and an antifoam?

A defoamer breaks foam that already exists; an antifoam is added beforehand to stop foam forming. In practice most products do both, and the terms are used interchangeably.

Which defoamer is best for an STP or ETP?

Silicone emulsion defoamers are widely used in aeration tanks because they work at low doses. Where silicone is a concern, a non-silicone defoamer can be used. Tell us your plant and we will suggest a type to trial.

Why is there brown foam on my aeration tank?

Thick, stable brown foam is often caused by filamentous bacteria such as Nocardia, linked to long sludge age, fats and grease or low oxygen. A defoamer controls it, but process changes are usually needed to stop it coming back.

Can too much defoamer cause problems?

Yes. Overdosing can reduce oxygen transfer in aeration tanks, leave residues, and affect downstream filters or membranes. Use the lowest dose that controls the foam.

Is a silicone defoamer safe for RO membranes?

Silicone can foul membranes, so avoid dosing silicone defoamers in streams that feed an RO plant. Ask us for a suitable alternative if your treated water goes to RO.

What is the HSN code for defoamer?

Defoamers are classified according to their composition; silicone-based products often fall under HSN 3910 and many formulated defoamers under 3824. Confirm the exact code on our invoice or with your tax adviser.

Do you supply defoamer in bulk?

Yes, we supply defoamers in cans and drums for plants and industrial users. Tell us your monthly usage for a quote.