What term describes the amount of Chlorine in mg/L used up by reacting with iron, organics, or bacteria?

The term that describes the amount of chlorine in milligrams per liter (mg/L) that is consumed through reactions with substances such as iron, organics, or bacteria is "demand." In water treatment, chlorine is often added to disinfect water, but it does not remain in the water in its entirety. Instead, a portion of the chlorine is utilized to react with various contaminants, which is referred to as chlorine demand.

Understanding chlorine demand is crucial for water treatment processes. It helps operators determine how much chlorine needs to be added to ensure effective disinfection while also accounting for the chlorine that will be used up in reactions with other materials. This distinction is important for maintaining water quality and ensuring that adequate residual chlorine remains to protect against pathogens.

Other terms such as residual, residue, and dosage represent different concepts in the context of chlorine usage. Residual refers to the amount of chlorine that remains in the water after reactions have taken place, while residue typically refers to any remaining substance after a process has occurred. Dosage denotes the amount of chlorine added to the water, which may not reflect the chlorine that has reacted or been consumed in the treatment process.