Which gas is associated with a rotten egg odor in water systems?

Which gas is associated with a rotten egg odor in water systems?

• A. Chlorine
• B. Oxygen
• C. Nitrates
• D. Hydrogen sulfide

Answer: (D)

Rotten egg odor in water systems comes from hydrogen sulfide. This gas is produced when sulfur compounds are reduced by sulfur-reducing bacteria in anaerobic conditions, such as in groundwater, wells, or sediment pockets. Even very low concentrations of hydrogen sulfide can give water a noticeable rotten egg smell, which is a practical clue for operators to identify anaerobic conditions and potential odor issues in the system. Chlorine can produce a chlorine-like or bleach smell, not a rotten egg odor. Oxygen itself has no detectable odor in typical water scenarios. Nitrates do not have an odor either. So the distinctive rotten egg smell points to hydrogen sulfide as the responsible gas.

Rotten egg odor in water systems comes from hydrogen sulfide. This gas is produced when sulfur compounds are reduced by sulfur-reducing bacteria in anaerobic conditions, such as in groundwater, wells, or sediment pockets. Even very low concentrations of hydrogen sulfide can give water a noticeable rotten egg smell, which is a practical clue for operators to identify anaerobic conditions and potential odor issues in the system.

Chlorine can produce a chlorine-like or bleach smell, not a rotten egg odor. Oxygen itself has no detectable odor in typical water scenarios. Nitrates do not have an odor either. So the distinctive rotten egg smell points to hydrogen sulfide as the responsible gas.