Scaling-up of the photocatalytic inactivation of E. coli with TiO2 in suspension

MARUGÁN, J.; VAN GRIEKEN, R.; PABLOS, C.; SATUF, M. L.; CASSANO, A. E.; ALFANO, O. M.

Valladolid

Conferencia; IWA Specialist Conferences. Water and Industry 2011; 2011

International Water Association

Chlorination processes for disinfection of drinking water supplies have raised public concerns as a consequence of the formation of potentially harmful chloro-organic disinfection by-products (DBPs) coming from the reaction with naturally-occurring organic matter. Among the processes currently in development, semiconductor photocatalysis has emerged as a very attractive, environmentally friendly technology for water disinfection. Most of the work in the literature was focused on the study of operational parameters. However, only relatively few developments have been achieved from the scaling-up and the photoreactor engineering viewpoints. The aim of this work is the development of a methodology for the design and scaling-up of large slurry photoreactors for the photocatalytic inactivation of bacteria with TiO2 in suspension. Photocatalytic experiments were carried out using commercial Degussa P25 titanium dioxide. The lab-scale photoreactor used to calculate the kinetic parameters consists of an annular photoreactor operating in a closed recirculating circuit driven with a reservoir tank, being the total working volume of 1 L. The validation of the kinetic model has been carried out in a bench scale annular photoreactor of 1250 cm3 of irradiated volume, operating in a closed recirculating circuit with a stirred reservoir tank of 5 L. Escherichia coli K12 strains were used to prepare the bacterial suspensions. Experimental data for the verification of the kinetic model have been obtained in a wide range of values of catalyst loading, irradiation power and initial concentration of bacteria. The experimental results obtained in the bench scale reactor and the predictions of the simulation model using the intrinsic kinetic parameters estimated in the lab reactor have allowed the validation of not only of the mechanistic kinetic model but also of the radiation models of both the lab and the bench scale reactor and additionally the methodology used for scaling-up.