What does DPD measure in water treatment?

DPD, or N,N-diethyl-p-phenylenediamine, is a chemical reagent commonly used in water treatment to measure chlorine residual. The DPD method is a colorimetric test, where the presence of chlorine in the water reacts with the DPD reagent, resulting in a color change that can be quantified using a colorimeter. This is important for water treatment because maintaining an adequate chlorine residual is crucial for ensuring disinfection and the overall safety of drinking water.

While the other options refer to different water quality parameters—such as pH, conductivity, and turbidity—they do not utilize DPD as a measurement method. Measuring pH, for instance, typically involves pH meters or indicator solutions rather than DPD, conductivity is assessed through conductivity meters, and turbidity is evaluated using turbidimeters. The specificity of DPD to chlorine residual makes it a vital tool in monitoring the effectiveness of disinfection processes in water treatment facilities.