S634 can maintain good anti-foam effect at low concentration, and is suitable for direct addition at low and high temperature. It is one highly efficient defoamer developed for various biological water recycling treatment systems. The features is below: can eliminate biological bubbles, static and dynamic bubbles, large bubbles, high viscous liquid bubbles; fast defoaming, long time foam suppression, low dosage, and non-toxic, no adverse side effects. In particular, it has no side effects on various bacteria in water treatment. It is highly dispersible in water and is well compatible with liquid products.