How is the effectiveness of disinfection generally measured?

The effectiveness of disinfection is primarily measured by the concepts of contact time and log reduction. Contact time refers to the duration that the disinfectant is in contact with the microorganisms in the water. The longer the contact time, the more effective the disinfection process will be in reducing or eliminating pathogens.

Log reduction quantifies the effectiveness of disinfection in terms of the logarithmic decrease of microorganisms. For instance, a 1-log reduction means that 90% of the microorganisms are inactivated, a 2-log reduction results in 99% inactivation, and so on. This method provides a clear and measurable indication of how well the disinfection process has worked, allowing operators to assess whether the disinfection standards for safe drinking water are being met.

While factors like water temperature, pH level, and water clarity can influence the disinfection process and its effectiveness, they do not directly measure the actual effectiveness of disinfection as contact time and log reduction do. Understanding this concept is crucial for ensuring safe drinking water and maintaining public health standards in water treatment practices.