Several mathematical models are developed to explain microorganism responses to ultraviolet irradiation. During this study, Pseudomonas aeruginosa was taken as a microorganism model. The experimental results obtained during a batch UV-reactor established that the disinfection kinetics is far from being uniform over the batch. Application of the first-order Chick-Watson model, in its original form or modified form, to validate the speed changes over the disinfection process, does not report any significantly improved results. Application of the Collins-Selleck model fits better the kinetic curves of UV disinfection of wastewater for all the tested strains of P. aeruginosa. At the same time, various continuous alternative reactors are checked, by accounting for the fluid flow hydrodynamics, that is, a perfectly mixing reactor without and with short circuits in the flow stream, or without and with dead zone inside the reactor, a plug flow reactor, and a series of perfectly mixed reactors. The results indicate that the succession of 4 perfectly mixed reactors is the best alternative to the process scale-up.
Key words: Disinfection, hydrodynamics, kinetics model, reactor of disinfection, treated wastewater, UV radiation.