Which of the following will not be measured in the total chlorine residual?

Total chlorine residual refers to the sum of all forms of chlorine present in a water sample, which includes free chlorine (the portion of chlorine that is available to react with other substances) and combined chlorine (chlorine that is chemically combined with ammonia or organic compounds).

The chloride ion is not a form of chlorine that contributes to total chlorine residual because it represents the stable ionic form of chlorine that does not have disinfection properties. While it is an end product of chlorine disinfection processes (where chlorine reacts to form various compounds), it does not participate in the residual measurement due to its lack of reactive chlorine species.

On the other hand, hypochlorite ion, monochloramine, and hypochlorous acid are all active forms of chlorine that contribute to the total chlorine residual as they play roles in disinfection and are present in water as part of the chlorination process. Understanding the distinction between reactive forms of chlorine and stable ions like chloride is critical in wastewater treatment operations, as it impacts the assessment of disinfection effectiveness and regulatory compliance.