Light intensity models for annular UV disinfection reactors

The finite-length lamp model was compared to the infinite-length lamp model (or parallel radiation model) for annular reactors, specifically for the purpose of calculating average light intensities. Based upon the specified conditions that both models must apply equal energy to a reactor, such as is expected when the average surface flux of energy is measured by a chemical actinometric method, the results for the average intensity were very similar for the two models. Long lamp length and short reactor radius favored conditions where the finite-length model predicted a slightly higher average intensity than that calculated using the infinite-length model. The inactivation of f2 virus was predicted in a completely mixed flow-through reactor using kinetic data obtained from batch reactions. For the particular flow-through reactor used, very little difference for the average intensity was calculated using the two intensity models. Indeed, predictions of reaction results using both models yielded results well within the range of experimental error.