Chlorine is categorized as which pollutant type?

• A. Conventional
• B. Primary
• C. Toxic
• D. Nonconventional

Answer: (D)

In wastewater categories, pollutants are grouped to help focus treatment and regulatory approaches. Conventional pollutants are the basic indicators of wastewater strength, like BOD, total suspended solids, pH, and fecal coliform. Chlorine doesn’t measure these strength indicators and is not part of that traditional set. It’s a chemical disinfectant residual that needs its own handling considerations, so it’s placed in the nonconventional group. This category covers a broad mix of other chemicals and substances that aren’t the standard strength indicators, including residual disinfectants and related compounds. While chlorine can be toxic, this framework groups it with other nonconventional pollutants rather than with the conventional indicators or with a separate “toxic” category.