Journal of Pure and Applied MicrobiologyVol. 9 No. 3

Optimization Electrophotocatalytic Removal of Streptococcus faecalis from Water by Taguchi Model

G. Kashi* and Sh. Aliannejad

Department of Environmental Health, Islamic Azad University, Tehran Medical Sciences Branch, Khaghani St. Shariati Ave, Tehran State, Postal code: 19395/1495, Iran.

Received on 21 April 2015 and accepted on 30 June 2015

 

ABSTRACT

Application of electrophotocatalytic (EPC) methods for drinking water disinfection was broadly used in the recent years. These methods led to producing of strong oxidant agents such as hydroxyl (OH-) radical. The goal of this applied-analytical research was to investigate of Streptococcus faecalis (S. faecalis), as a microbial indicator, removal from urban drinking water by batch EPC reactor with using zinc oxide (ZnO) nanoparticles immobilized on zinc (Zn) sheet-copper electrode, and lamp emitting dynode (LED) ultraviolet-A (UV-A) lamp. The contaminated water sample was prepared by adding 5×101-5×102 cells of S. faecalis bacteria per ml of drinking water. The studied variables were pH (6-8), the number of bacteria (5×101-5×102 cells / ml), the lamp intensity (120-360 mW cm-2), radiation time (5-30 min), the distance between lamp and electrode (1.5 cm), layering of zinc oxide nanoparticles (1-3), and current density (3-9 mW cm-2). The results showed the correlation between removal of cells and UV-A lamp intensity, current density, and radiation time. Optimal removal (0) was obtained at pH 8, radiation time: 5 minutes, 2- layer of ZnO nanoparticles, and current density of 3 mW cm-2. The findings indicated that removal efficiency was increased with increasing current density, radiation time, and lamp intensity.

Keywords : Bacterium; Lamp emitting dynode; Electrophotocatalytic; Streptococcus faecalis; Urban drinking water.