Effects of number of low-pressure ultraviolet lamps on disinfection performance of a water reactor

In recent years, the experimental and numerical investigations of water ultraviolet (UV) reactors have increased significantly. In this study, a CFD model utilizing a Lagrangian-Eulerian method is applied to analyze the disinfection performance of a closed conduit reactor containing four low-pressure (LP) UV lamps perpendicular to the flow. A discrete ordinates (DO) model is employed to evaluate the UV irradiance field. In addition to the reference model, some other models were also defined with different number and arrangement of active lamps to examine the degree of importance of each lamp in inactivating microorganisms. The results from two inactivation kinetics show that inactivation performance of the model with two central lamps in operation corresponds to 88-99% of the reference model data. Furthermore, as a lamp is closer to the main flow region, it has more influence on microbial inactivation. The effect of water flow rate, inlet water temperature and lamp power are also studied.