In odor control for a wastewater plant, which method is commonly used to reduce hydrogen sulfide and ammonia emissions?

• A. Odor scrubbers (chemical or biological) or activated carbon filtration.
• B. Increase aeration in downstream basins.
• C. Add sulfuric acid to neutralize odors.
• D. Remove sulfates from water.

Answer: (D)

Odor control in wastewater plants focuses on removing or neutralizing the compounds that actually cause smells before they escape as gas. Hydrogen sulfide and ammonia are two common culprits, and the most reliable way to cut their emissions is to treat the odor-laden air or water with systems designed to remove or transform those compounds. Odor scrubbers—whether chemical or biological—oxidize or convert H2S and NH3, while activated carbon filtration adsorbs these volatile molecules from the air stream. These methods are widely used because they directly target and reduce the odorous compounds at the source of emissions.

Removing sulfates from water doesn’t address the volatile gases that cause odors, so it isn’t a practical odor-control approach.