Wastewater Treatment Operator Certification Practice Test

What is a common method used to control hydrogen sulfide odor in wastewater treatment?

1. Carbon Dioxide

2. Methane

3. Chlorine

4. Hydrogen

The correct answer is: Chlorine

Chlorine is commonly used in wastewater treatment to control hydrogen sulfide odor due to its strong oxidizing properties. Hydrogen sulfide, which is produced in anaerobic conditions, has a characteristic rotten egg smell and can be harmful to both public health and the environment. When chlorine is added to wastewater, it reacts with hydrogen sulfide, oxidizing it into sulfate, which is odorless. This not only mitigates the unpleasant odor but also reduces the concentration of harmful compounds in the water. In contrast to other options, chlorine's effectiveness as a disinfectant and oxidizer makes it particularly suited for this purpose. While carbon dioxide and methane are gases that can be found in wastewater systems, they do not have oxidative properties that would help control odors. Hydrogen, similarly, would not contribute to odor control in a practical sense. Thus, chlorine stands out as the appropriate choice for this function in wastewater treatment.