If fine-bubble diffusers are used to introduce air into a biological reactor, the surface of the tank will typically have what type of appearance?

If fine-bubble diffusers are used to introduce air into a biological reactor, the surface of the tank will typically have what type of appearance?

• A. Calm surface with no foam
• B. Heavily foamed across the entire surface
• C. Mildly agitated, partially covered with light foam
• D. Rough surface with dark patches

Answer: (C)