Aqueous microorganisms inactivation by photocatalytic reaction

Photocatalysis by TiO2 is a new technology which can treat water without ad ding any chemicals. In this research, the disinfections of three microorgan isms such as bacteriophage alpha beta, E. coli and Cryptosporidium parvum w ere investigated. An immobilized TiO2 reactor was used and UV lamp and Blac k light (BL) lamp were used as light source. The intensity of each lamp was set up to equalize the photocatalysis efficiency determined by the decompo sition rate of Methylene Blue. The additive effect of TiO2 to inactivation did not appear in the E. coli experiments with UV and BL irradiation or in the alpha beta experiment with UV. In these three cases, light irradiation gave a high germicidal effect and the addition of inactivation by photocata lysis was relatively too small to be significant. In the alpha beta experim ent with BL and in he Cryptosporidium experiment with UV and BL, the additi ve effect by TiO2 could be seen clearly because these microorganisms were r esistant to light irradiation in these cases. in spite of setting equal pho tocatalysis efficiency in both lamp reactors, UV photocatalytic inactivatio n of Cryptosporidium was much faster than BL. It is assumed that UV and pho tocatalysis enhanced each other.