Which statement describes a disadvantage of aerobic digestion?

• A. Aeration costs are negligible.
• B. High aeration costs are a disadvantage of aerobic digestion.
• C. Aerobic digestion produces no odor.
• D. It requires no energy input.

Answer: (B)

Maintaining an aerobic digestion system requires a constant supply of oxygen, delivered by aeration equipment powered by blowers and diffusers. That oxygen transfer uses a lot of electrical energy, so the operating costs tied to aeration are typically a major disadvantage.

The other statements aren’t accurate: aeration costs aren’t negligible in practice, aerobic processes don’t guarantee no odor ( odors can still occur if conditions aren’t well controlled), and aerobic digestion does require energy input to run the aeration and mixing equipment.