Journal of School of Public Health and

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Background and Aim: The scattered state of the rural populations- in terms of both the distance between villages and the distance between residential units within a single village- has made the task of supply, distribution and monitoring the quality of water a difficult one. In this study we looked at the bacteriological quality as well as access to safe potable water in selected villages of Tehran Province. This research started in February 2006 and ended in July the same year.

Materials and Methods: In this cross-sectional field study, sampling points were specified on the basis of the populations of the villages served by the Tehran Rural Water and Wastewater Company. After systematic sampling, the specimens were transferred to the laboratory for testing. Data were analyzed using the SPSS and Microsoft Excel software packages.

Results: Drinking water contamination with E. coli was observed in 5.99% of the villages. The degree of contamination was highest in the districts of Pakdasht, Savojblagh and Damavand, with rates of 33.34, 13.69 and 13.32 percent respectively. For 99.36% of the Tehran rural population the turbidity was lower than the standard value of 1053 set by the Iranian Institute of Standards and Industrial Research. Values in Savojblagh and Varamin were relatively higher, with rates of 96.51% and 99.30% respectively. Given the standard value of 1053, the residual chlorine levels were unacceptably low for 92.39% of the rural residents, with figures in the districts of Pakdasht, Damavand and Robatkarim reaching 75.67, 85.45 and 83.98 percent respectively.

Conclusion: Based on WHO guidelines concerning the microbial quality of water published in 2006, the average indicator for lack of E.coli in rural water of Tehran was 94.01%, i.e. at an excellent level. Levels were good for Damavand and Savojblagh, low in Pakdasht and excellent in all other districts.

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Background and Aims: In this study we measured the quality, corrosiveness, Ryznar stability index, and heavy metal leakage in the drinking water distribution networks of Ahvaz.

Materials and Methods : A total of 76 sampling sites were selected for this purpose the sites included inlet and outlet points in water treatment plants as well as consumers taps. We collected 456 samples in six stages and over a period of six month, following the procedures outlined in the Standard Method. Data were analyzed using the SPSS 11.5 software package.

Results: The average values obtained from the specimens were as follows: temperature (19 0C), turbidity (1.97NTU), pH (7.31), pHs (7.88), EC (1678µs/cm), TDS (1006mg/l), Alkalinity (129mg/l), Calcium (109mg/l), DO (6.78mg/l), Cl- (293mg/l), SO4-- (264mg/l), Ryznar stability index (8.43). Average heavy metal levels in tap water were as follows: Pb (8.48µg/l), Cd (0.972 µg/l), Zn (3.18 mg/l), Cu (0.168 g/l), Fe (0.257 mg/l), and Mn (0.031mg/l).

Conclusion: The results showed that the water quality has been affected in such a way as to cause corrosiveness, heavy metal leakage and aesthetic problems. We also showed that in comparison with USEPA and Iranian standards, the quality indices of the drinking water in Ahvaz were at an acceptable level, with the notable exception of a few indices such as TDS, EC, and hardness. The Ryznar stability index indicated that the drinking water in Ahvaz has corrosive properties and this could be one of the reasons behind the high rates of heavy metal leakage detected in this area.

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Background and Aim: Methyl tertiary butyl ether (MTBE) is an oxygenated additive chemical added to gasoline, which is as a substitute for tetra ethyl lead, to reduce discharge of pollutants from automobile exhausts. This organic chemical is present in water samples collected from areas where gasoline wastes are abundant. The objective of this study was to investigate the possibility of MTBE removal from drinking water at the point of use (POU) by using an Iranian granulated active carbon (GAC) bed.
Materials and Methods: Adsorption of MTBE from drinking water at POU was studied by using an Iranian GAC bed. The water samples treated by this filter adsorber were prepared synthetically at two concentrations (50 ppb and 100 ppb). In addition, the effects of residual chlorine at concentrations of 0.2 and 0.5 mg/L and of chloroform at a concentration of 100 ppb on removal of MTBE were determined.
Results: It was found that this filter adsorber could treat 375 liters of water containing 50 ppb MTBE, 100 ppb chloroform and 0.2 ppm residual chorine. If the residual chlorine content was increased to 0.5 ppb, the volume of water treated would be 335 liters. The filter could t eat 195 liters of water containing 100 ppb MTBE, 100 ppb chloroform and 0.2 ppm residual chlorine to acceptable levels for drinking, provided the amount of MTBE is below the respective standard.
Conclusion: Both residual chlorine and chloroform reduced the MTBE adsorption capacity on GAC due to occupation of adsorption sites. In addition, to the tendency of GAC to adsorb chloroform and chlorine was greater than that of MTBE.

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Background and Aim: Recently the use of heterotrophic plate count (HPC) has received much attention as a supplementary indicator of the MPN test in water quality control. The US Environmental Protection Agency (USEPA) has declared 500 cfu/mL as the maximum acceptable level for heterotrophic bacteria in distribution networks. Currently the HPC determination is not among the routine control items in Tabriz city and there is no published information on the presence of heterotrophic bacteria in that city's potable water. In this study the presence of HPC in potable water main was determined in Tabriz city, Iran.
Materials and Methods: A total of 50 water samples, representing drinking water of the whole city of Tabriz, were taken randomly from different districts of Tabriz city and their HPC, coliform, residual chlorine, turbidity, temperature, and pH were measured. For the heterotrophic bacteria the R2A and Nutrients Agar culture media were used, while the spread plate count method was used for the HPC test. The statistical tests used for data analysis were the t-test and regression.
Results: In 50% of the samples heterotrophic bacteria were present. In 6 districts the HPC was higher than 500 cfu/mL. Based on Nutrient Agar and R2A, the HPC indicator in Tabriz drinking water was 184±340 and 154±315 cfu/mL, respectively, the growth rate being higher in the former medium. There was a significant correlation between the HPC and residual chlorine in both media (for Nutrients Agar, p<0.05 R= -0.347, and for R2A, p<0.05 R= -0.312). Also, there was a significant positive correlation between the HPC and pH (p<0.05). Further analysis of the data showed that the correlation between HPC values in both media was also significant (p<0.95, R= 0.95).
Conclusion: The presence of heterotrophic bacteria in 50% of the water samples tested indicates that drinking water contamination with these bacteria is a public health problem in Tabriz city. As a result, monitoring of HPC at least once every 6 or, at least, 12 months, together with coliform bacteria, and the comparison of the results over time can help to better determine water quality in the distribution system, as well as boost the system operation and ensure drinking water with a high quality.