AWWA WQTC71606

During ultraviolet (UV) reactor validation, dose delivery, defined as Reduction Equivalent Dose (RED), is typically quantified across different operating conditions of flow rate, UV transmittance (UVT), lamp output and in some cases, lamp status. Empirical models (calculated dose algorithms) are then developed from the validation data to express the measured RED as a function of the different operating parameters. At installations, these algorithms are used to calculate the RED, given operating conditions of each parameter. An alternative dose-monitoring strategy, known as the UV intensity setpoint approach, can be defined by quantifying a UV reactor's RED as a function of flow and lamp output. Per the German UV guidelines (DVGW) intensity setpoint approach, the RED is confirmed at two test points with the reactor operating at a fixed flow and lamp output (setpoint UV intensity); one at high UVT but with lamp power reduced till the UV intensity matches the setpoint, and the other at maximum power but with UVT reduced until the UV intensity matches the setpoint. In the field, a UV reactor is credited with the validated RED if the measured flow does not exceed the validated flow and the measured UV intensity matches or exceeds the setpoint UV intensity. In this paper, a new method is described whereby the calculated dose approach was used to define an online dose-monitoring strategy that, like the UV intensity setpoint approach, does not require UVT input. Includes figures.