One of the best solutions for the deficiency of clean water, especially for developing countries, is rainwater disinfection. In the past decades a lot of studies have been made to develop photocatalytic processes using TiO2 determining the performance on their surface oriented photocatalysis. However, most of these researches failed to consider the economical aspect as well as the effectiveness on the disinfection to antibiotic resistance genes. On the other hand, due to the issues of climate change and increased impermeable layer in urban area, flooding prevention is the best solution in water management systems. To remedy these two problems, a roof-harvested rainwater storage system was designed. In addition, a breakthrough technique using a solar simulator with self-rotating TiO2 nanotubes, to apply a photocatalytic system in disinfecting storage rainwater harvested from roof, was established. Roof-harvested storage rainwater was analysed for TN, TP, SS and COD. Aside from these parameters, Escherichia coli (with multidrug resistant pB10 plasmid) was added to the sample. Samples were injected to the self-rotating TiO2 nanotube reactor system with exposure time of 0 to 360 min and 7 different setups. Results show that the developed system has increased disinfection properties compared to negative samples, though the presence of antibiotic resistant bacteria.

The current study evaluated the technical feasibility of the application of titanium dioxide (TiO2) photocatalytic air cleaners for the disinfection of bioaerosols present in indoor air. The evaluation included both laboratory and field tests and the tests of hydraulic diameter (HD) and lamp type (LT). Disinfection efficiency of photocatalytic oxidation (PCO) technique was estimated by survival ratio of bacteria or fungi calculated from the number of viable cells which form colonies on the nutrient agar plates. It was suggested that the reactor coating with TiO2 did not enhance the adsorption of bioaerosols, and that the UV irradiation has certain extent of disinfection efficiency. The disinfection efficiency increased as HD decreased, most likely due to the decrease in the light intensity since the distance of the catalyst from the light source increased when increasing the HD. It was further suggested that the mass transfer effects were not as important as the light intensity effects on the PCO disinfection efficiency of bioaerosols. Germicidal lamp was superior to the black lamp for the disinfection of airborne bacteria and fungi, which is supported by the finding that the disinfection efficiencies were higher when the germicidal lamp was used compared to the black lamp in the laboratory test. These findings, combined with operational attributes such as a low pressure drop across the reactor and ambient temperature operation, can make the PCO reactor a possible tool in the effort to improve indoor bioaerosol levels.