Noroozi , R, Mehdinezhad, Mh, Zafarzadeh A,
Volume 5, Issue 2 (Autumn – Winter 2011[PERSIAN] 2011)
Abstract
Abstract: Background and objectives: There is a great interest in photocatalytic oxidation of contaminants, using ZnO, in recent years. The main objective of this research was to study photocatalytic disinfection of E. coli bacteria as water microbial pollution index, using nano particles of ZnO and a UV lamp in a batch reactor. Material and Methods: In this study, the contaminated water sample was prepared through adding 102 and 103 E. coli bacteria per ml of raw water. The contaminated water entered the photocatalytic oxidation reactor and removal efficiency of E. coli bacteria in different conditions were studied, including pH (5.5, 7, and 9), time (10, 20, 30, 40, 50 and 60 mins), dose of nano particles ZnO (0.2,0.4,0.8 and 1 gr/l), number of bacterium (102 and 103 per milliliter) and voltage of UV-C lamp, 27 volts. Characterizations of ZnO nanoparticles were determined using scanning electron microscope equipped with Energy Dispersive X-ray Analysis (EDX) system and X-ray diffraction (XRD) method. Results: Photocatalytic process efficiency is enhanced by increasing reaction time and dose of nano particles ZnO in the presence of UV lamp irradiation. The results show that the best conditions for removal of 102 and 103 bacteria per milliliter are obtained from condition including pH of 7, reaction time of 30 mins, 0.8 gr/l doses of nano particles ZnO and 27-volt-UV lamp. Conclusion: The results indicate that the increase of reaction time and dose of nano particles ZnO, in the presence of radiation UV lamp, have the most significant effect on photocatalytic efficiency. Based on the results, photocatalytic can be promising method for removal of E. coli bacterium from drinking water. Keywords: Photocatalytic, E. coli, irradiation UV, ZnO nanoparticles, water treatment
A Zafarzadeh, N Amanidaz, N Seyedghasemi,
Volume 8, Issue 3 (Autumn[PERSIAN] 2014)
Abstract
Abstract
Background and Objective: Safe drinking water is essential for health and health promotion is dependent on providing safe water. We aimed to determine the relationship between turbidity & residual chlorine and microbial quality of drinking water in Agh ghala.
Material and Methods: In this descriptive-analytical study, 2079 water samples were collected from water networks of 78 villages and urban network using census sampling during two years. Both sampling and tests were performed on the basis of standard methods.
Results: In more than 96 percent of the villages (N =75), above 90% of the samples hadn’t any fecal coliform bacteria except three villages that had the index in the range of 85 to 88 percent. Residual chlorine had significant relationship with coliform and fecal coliform (P ≤ 0.05) while the relationship between turbidity and coliform contaminants, fecal coliform and residual chlorine was not significant.
Conclusion: Total coliform and fecal coliforms were reducing by increasing residual chlorine in the water supply networks. It has been suggested that the officials reduce the water turbidity and annual washing of the water network to increase the effect of residual chlorine and decrease bacterial contamination.
Keywords: Agh Ghalla, Fecal Coliform, Coliform, Residual Chlorine
Zafarzadeh, A, Amanidaz, N, Bay, A, Aghapour, Sm,
Volume 9, Issue 2 (may,jun 2015[PERSIAN] 2015)
Abstract
Background and objective: Bioindicators of drinking water are always influenced by physical and chemical factors such as turbidity and chlorine. Considering the assessment of drinking water quality is based on residual chlorine, E.coli, heterotrophic bacteria and turbidity. We aimed to evaluate the effect of pH, chlorine residual and turbidity on the microbial bioindicators.
Material and methods: In this descriptive-analytic study, 324 and 32 water samples were collected from rural and urban water distribution network of Aq Qala city in 2013, respectively. All steps were performed according to standard methods.
Results: In rural water supply, 5%, 9% and 33% of the samples were contaminated with fecal coliform, fecal streptococcus and the heterotrophic more than 500CFU / ml. In urban network, coliform contamination was not seen and other bioindicators were less than those of rural networks were. Turbidity of above 5 NTU in urban and rural samples was 3 and 9 percent, respectively. Bioindicators had significant relationship with residual chlorine, fecal coliform bacteria with pH and turbidity with heterotrophic bacteria (P ≤0.05).
Conclusion: The presence of fecal streptococcus bacteria in some samples without fecal coliform cannot confirm the safety of drinking water. Microbial contamination in the presence of residual chlorine implies that just chlorination is not enough for having healthy water.
Keywords: Chlorine, Turbidity, Biological Factors, Drinking water
