Hospital laundry wastewater disinfection with catalytic photoozonation

Wastewater production in a hospital laundry and the treatment of the most critical wastewater stream, are assessed. Hospital laundry wastewaters are hazardous to the environment due to their high pollutant concentrations and the chemicals added during the clothes washing process. Heterogeneous photocatalysis with UV, O-3 and TiO2 and their possible combinations were used for disinfection purposes. A ramptype reactor was used for TiO2 (P25 Degussa) fixation and for photochemical diffusion of the ozonized air. After assessing 5-day biological oxygen demand, chemical oxygen demand, pH, turbidity, and surfactant content, and checking for the presence of thermotolerant coliforms and Escherichia coli, it was concluded that UV/O-3/TiO2 was the best process/combination, yielding a 100% disinfection rate and a microbiological inactivation of 0.5070 min(-1) for E. coli and of 0.5505 min(-1) for thermotolerant coliforms.