What is the main purpose of mechanical aeration?

• A. Increase mixing
• B. Reduce odors
• C. Add DO and keep food and bugs in contact
• D. Cool the water

Answer: (C)

Mechanical aeration is all about getting air into the wastewater to supply oxygen for the biological treatment. By increasing dissolved oxygen, aerobic bacteria can effectively digest the organic matter present. At the same time, the mixing keeps the organic “food” in contact with the microorganisms, which speeds up the breakdown process. Odor reduction can happen as a side effect of keeping conditions aerobic, but it isn’t the primary purpose, and cooling the water isn’t a goal of aeration. So the best description is that it adds dissolved oxygen and keeps the food and the bugs in contact, enabling efficient biodegradation.