Which of the following is a common disinfectant used in wastewater treatment?

• A. Hydrogen peroxide
• B. Chlorine
• C. Acetic acid
• D. Carbon dioxide

Answer: (B)

Chlorine is widely recognized as a common disinfectant used in wastewater treatment due to its effective microbial inactivation properties. It works by disrupting cellular functions, thus killing bacteria, viruses, and other pathogens present in wastewater. Chlorine can be added in various forms, such as gas, liquid, or solid, and it effectively reduces the risk of waterborne diseases when the treated effluent is released into the environment.

In addition to its efficacy, chlorine also has the ability to provide residual disinfection in the treated effluent, meaning that it continues to work even after the initial treatment process, offering a safeguard against re-contamination. The use of chlorine for disinfection is a critical step in ensuring that reused or discharged wastewater meets health and safety standards.

Other substances like hydrogen peroxide and acetic acid are less commonly used for disinfection in wastewater applications. While hydrogen peroxide can act as an oxidizing agent, it is not typically used for widespread disinfection in wastewater treatment due to its higher cost and lower effectiveness compared to chlorine. Acetic acid is primarily used to control pH rather than as a disinfectant. Carbon dioxide plays a role in pH adjustment as well, but it does not possess disinfecting properties. Therefore, chlorine stands out as the