A common drawback of extended aeration systems is what?

• A. Large footprint
• B. Low energy use
• C. Simple to operate
• D. High electrical costs

Answer: (D)

Extended aeration keeps the treatment process in the aeration tank for a longer period to achieve thorough organic removal. That means the aerators must run longer and at adequate oxygen levels, which requires more air supply and power. The result is noticeably higher electrical costs as the primary ongoing expense of this system. Footprint and ease of operation aren’t as defining as the energy demand: the size can vary with design, and while operation requires some control, the defining drawback people notice first is the higher electricity bill driven by extended aeration.