Surfactants from cleaners can cause which issues in a wastewater treatment plant?

• A. Interfere with solids settling and create foam
• B. Increase phosphorus removal
• C. Improve sludge digestion
• D. Decrease ammonia production

Answer: (A)

Surfactants are surface-active compounds that cleaners put into wastewater. Their main effects come from lowering surface tension and stabilizing air bubbles. When these agents enter a biological treatment system, they tend to coat solids and fats, which makes it harder for solids to clump into dense, settleable flocs. That means solids don’t settle as well in secondary clarifiers, leading to poor sludge blanket composition and more suspended solids escaping with the effluent.

At the same time, surfactants make bubbles easier to form and more stable, so foams develop in aeration basins and even at the water surface. Those persistent foams can carry solids upward and interfere with normal settling and clarifier operation, further degrading treatment efficiency.

So surfactants from cleaners directly cause two common operational problems: interference with solids settling and the formation of foam.