Which parameter is used to determine how much air must be supplied in the aeration process?

• A. BOD loading
• B. DO concentration
• C. Temperature
• D. Flow rate

Answer: (B)

Maintaining aerobic conditions hinges on keeping a target dissolved oxygen (DO) level in the aeration basin. The amount of air you supply is adjusted to hold that DO concentration at the desired setpoint. If the DO drops, you raise the airflow to replenish oxygen; if DO climbs, you can reduce or maintain the air flow. BOD loading indicates how much oxygen the wastewater will eventually require overall, so it guides design and expected oxygen demand, but it’s not the real-time signal used to control how much air is supplied. Temperature affects how much oxygen can be dissolved (warmer water holds less oxygen), which can influence how much air is needed to maintain the same DO, but the key control parameter is the DO concentration itself. Flow rate or influent volume changes total oxygen demand over time, yet the immediate air control still revolves around maintaining the target DO.