Photocatalytic degradation of E. coliform in water.

This study aims to further investigate the total mineralization of the bacteria to the extent of death and cell-mass inactivation using a TiO2-Fe2O3 membrane photocatalytic oxidation reactor. Experimental results clearly indicated that dissolved oxygen (DO), hydraulic retention time (HRT) and concentration of the model bacteria (Escherichia coliform) affected the removal efficiency. It was found that the ultimate removal efficiency was 99% at DO level of 21.34 mg/l, HRT at 60s and high concentration of E. coli at 10(9)CFU/ml. The morphologic studies also showed that E. coliform could be further mineralized into CO2 and H2O. Dissolved organic carbon, pH and gas chromatograph analysis had justified most importantly the evolution of CO2. Experimental results revealed that the photomineralization rate of E. coliform followed pseudo-first-order kinetics by the role of DO. The derived empirical models were found consistent with the proposed reaction pathways of a combined UV breakdown on mass cell and a dual-site Langmuir-Hinshelwood mechanism where the rate-controlling step is the surface interaction between the adsorbed cleavage bacterial cells and hydroxyl radicals.