Photocatalytic Inactivation of Bacteriophage Bioaerosols in the Dairy Industry

A proposed methodology for the photocatalytic inactivation of bacteriophages contained in bioaerosols in the dairy industry is presented. Experimental tests were carried out with several phages that infect lactic acid bacteria (LAB) in a simple laboratory reactor with TiO2-coated plates exposed to UV-A radiation and in a semipilot scale reactor that simulates different bioaerosol conditions. In order to compare the photocatalytic inactivation of these phages in photoreactor configurations under different operating conditions, the photonic and quantum efficiencies to carry out the process were determined. For the evaluation of the quantum efficiency, the optical properties of the photocatalyst immobilized on an inert support were determined and the net radiation or ray-tracing methods applied to calculate the fraction of energy absorbed by the TiO2 coatings on the support. Comparing the results of all the inactivated phages, it was observed that the quantum efficiencies differ by more than an order of magnitude and that the ATCC 8014-B1 phage presented the highest inactivation efficiency while the MLC-A phage showed the lowest. This approach has proven to be appropriate to evaluate and compare the photocatalytic inactivation of several dairy bacteriophages under different process operating conditions.