UV Radiation: An Alternative Disinfectant of Waters

M. LABAS, C. MARTÍN Y A. CASSANO

Río de Janeiro, Brasil

Congreso; 2nd Mercosur Congress on Chemical Engineering, 4th Mercosur Congress on Process Systems Engineering; 2005

Microbiological contamination of water has always been a problem of general concern.Among the proposed ways to deal with this type of pollution without difficulties associatedwith the use of chlorine, UV radiation is an established technology.This work presents a detailed kinetic study of the rate of removal of a model bacteria(Escherichia coli) employing UV radiation (253.7 nm) in a laboratory reactor where all the significant operating variables were carefully measured and controlled. A modification of theSeries-Event Model was used to interpret the experimental data which were collectedemploying four different levels of the incident radiation fed to the reactor. The developedmodel is based on a rather complex dependence with respect to the Escherichia colisignificant operating variables were carefully measured and controlled. A modification of theSeries-Event Model was used to interpret the experimental data which were collectedemploying four different levels of the incident radiation fed to the reactor. The developedmodel is based on a rather complex dependence with respect to the Escherichia colisignificant operating variables were carefully measured and controlled. A modification of theSeries-Event Model was used to interpret the experimental data which were collectedemploying four different levels of the incident radiation fed to the reactor. The developedmodel is based on a rather complex dependence with respect to the Escherichia colisignificant operating variables were carefully measured and controlled. A modification of theSeries-Event Model was used to interpret the experimental data which were collectedemploying four different levels of the incident radiation fed to the reactor. The developedmodel is based on a rather complex dependence with respect to the Escherichia coliEscherichia coli) employing UV radiation (253.7 nm) in a laboratory reactor where all the significant operating variables were carefully measured and controlled. A modification of theSeries-Event Model was used to interpret the experimental data which were collectedemploying four different levels of the incident radiation fed to the reactor. The developedmodel is based on a rather complex dependence with respect to the Escherichia coliEscherichia coli concentration and to the radiation that is effectively absorbed by the bacteria which wasprecisely quantified.The study was carried out in a well-stirred reactor of cylindrical shape irradiated from bothflat sides with two tubular lamps placed in the axial position of two parabolic reflectors. Thereactor was operated in a recycle. The concentration evolution was analyzed employing theplate count method with Petrifilm specific plates. The Incident Radiation at the reactor windows was measured with ferrioxalate actinometry.The kinetic constants of the model were obtained using a multiparameter optimizationprogram. They are: n = 2 (damage threshold); k=1.3142 x 102 s-1 (cm3 s/ Einstein)mwindows was measured with ferrioxalate actinometry.The kinetic constants of the model were obtained using a multiparameter optimizationprogram. They are: n = 2 (damage threshold); k=1.3142 x 102 s-1 (cm3 s/ Einstein)mwindows was measured with ferrioxalate actinometry.The kinetic constants of the model were obtained using a multiparameter optimizationprogram. They are: n = 2 (damage threshold); k=1.3142 x 102 s-1 (cm3 s/ Einstein)mwindows was measured with ferrioxalate actinometry.The kinetic constants of the model were obtained using a multiparameter optimizationprogram. They are: n = 2 (damage threshold); k=1.3142 x 102 s-1 (cm3 s/ Einstein)mspecific plates. The Incident Radiation at the reactor windows was measured with ferrioxalate actinometry.The kinetic constants of the model were obtained using a multiparameter optimizationprogram. They are: n = 2 (damage threshold); k=1.3142 x 102 s-1 (cm3 s/ Einstein)m2 s-1 (cm3 s/ Einstein)m (inactivation constant), m = 0.205 (the reaction order with respect to the absorbed radiation bythe bacteria). One of the most important conclusions of this work is the observed reactionorder with respect to the volumetric rate of radiation absorption by the bacteria. This resultmay have very important economical consequences.