What does the inactivation ratio (IR) represent?

The inactivation ratio (IR) is a critical parameter in water treatment, particularly when assessing the effectiveness of disinfection processes. The IR specifically compares the calculated CT value (which represents the product of concentration and time necessary for a disinfectant to achieve a specific level of pathogen inactivation) to the CT value associated with a desired level of inactivation, such as that required for 99.9% reduction of pathogens (CT99.9).

By using the relationship of CTcalc to CT99.9, the inactivation ratio provides a clear understanding of how much the treatment process is achieving in terms of pathogen reduction relative to the established standards. A higher IR indicates better disinfection, suggesting that the system is effectively removing or inactivating pathogens present in the water.

This performance measure helps water treatment facilities determine if they are meeting public health requirements for pathogen control and can guide process adjustments if the IR indicates insufficient inactivation.