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Background Inactivation of Heterotrophic Bacteria in Well Water Using ZVI , TiO 2 and ZnO Nanoparticles

There are several microbial indicators for assessment of the microbiological safety of drinking water. One of the standard methods for controlling of microbiological water quality in the water treatment systems is heterotrophic plate counts that described as colony-forming units (CFU) (1). High HPC is threatening to human health and may cause gastrointestinal diseases (2). In recent years, a lot of discussion has been raised about the effects of the common disinfectant in water, such as: carcinogenic effects, forming harmful disinfection byproducts (DBPs) (3,4) and microorganisms resistant that the need for research to find alternatives disinfection has increased (5). The rapid development of nanotechnology and its wide use in the environmental field due to high reactivity and the large surface area has attracted the attention of many studies (4,6-9). Nanotechnology has introduced different types of nanomaterial including Titanium dioxide (TiO2), silver nanoparticles, etc to water industry that can have antimicrobial properties (10-12). The several studies have been carried out on the use of TiO2 in the removal of contaminants from aquatic environments (4,10,13,14). The research showed that titanium dioxide can be effective in removal of different A-R-T-I-C-L-EI-N-F-O A-B-S-T-R-A-C-T Article Notes: Received: Mar 12, 2016 Received in revised form: May 15, 2016 Accepted: June 25, 2016 Available Online: July 5, 2016 Background & Aims of the Study: The heterotrophic bacteria are widely used as a water microbial pollution index for drinking water. The aim of this study was to investigate the effect of metallic nanoparticles such as Zero Valent Iron (ZVI), Titanium dioxide (TiO2) and Zinc oxide (ZnO) on Heterotrophic Bacteria inactivation in well water. Materials & Methods: We performed an experimental-laboratory study that the effect of nanoparticles type Zero valent iron (ZVI), Titanium Dioxide (TiO2) and Zinc oxide (ZnO)) in constant contact time (30 min) and nanoparticles dose (1 g/L) was investigated on heterotrophic bacteria inactivation. Results: The results showed that TiO2 was detected more effective than ZnO and ZVI. The HPC inactivation after 30 min of retention time by TiO2, ZnO and ZVI nanoparticles were 71.5, 50 and 36.4 as percent, respectively. The maximum bacteria inactivation was 98.82% in the presence of TiO2 nanoparticles. Conclusions: It is concluded that nanoparticles used in this study could be effectively used to increase the efficiency of removing heterotrophic bacteria from water and can be considered for microorganisms’ inactivation.