maryam ghani

The aim of this study was to evaluate the chemical and microbial quality of bottled water in Iran and to calculate the water quality index (WQI).

Different brands of bottled water (4 samples from 71 brands) were randomly collected from the market. Chemical and microbial characteristics of the samples were examined and determined. Finally, the calculations related to the WQI index were performed and the water samples were classified as excellent, good, poor, very poor and unsuitable.

None of the samples exhibited concentration of heavy metals beyond Iranian water standards, and the concentration of sulfate (SO4), chloride (Cl) and fluoride (F) did not exceed international standards. However, in some samples, nitrite (NO2) and nitrate (NO3) concentrations were higher than recommended standards. With Regard to other water quality parameters, 8% to 89% of the samples exhibited concentration higher than the values provided on the water bottle label. 5 species of different bacteria were found in 15 water samples. According to the WQI index, about 63% of the samples were of excellent quality. Also, the water quality of 34% and 3% of the samples fell in good and poor quality categories, respectively. None of the bottled water samples was of very poor quality.

The quality of bottled water investigated in this study was generally suitable, but due to the wide range of bottled water in Iran based on brand and seasons, continuous evaluation of water treatment methods in companies and careful monitoring of chemical and microbial quality of bottled water in all seasons is recommended.

The most common used methods for water disinfection were chemicals like chlorine, ozonation, ultraviolet radiation, membrane processes, etc. Water disinfection using irradiation techniques is new in water treatment industry which has been developed recently. The aim of the present study was to investigate radio frequency (RF) efficiency for the inactivation of total coliform (TC), fecal coliform, and heterotrophic bacterial count of water pellets. Tap water samples were taken from School of Public Health, Tehran University of Medical Sciences and irradiated using hydropad device, steam KLEAR model S-38 (1.2 W and frequency of 120-200 kHz). Microbial concentration was measured in cycles 1, 5, 10, 15, 20, 25, 30, 35, and 40 in 1 and 2 h contact time. Indicator bacteria were counted using plate count method and multiple fermentation tube technique. According to the microbial results, after 40 cycles and without chlorine residual, TC, fecal coliform, and heterotrophic bacteria were reduced by 86, 90, and 85%, while after 15 cycles and 0.8 mg/L chlorine residual, removal rate was 89, 91, and 89%, respectively. Furthermore, it was observed that after 2 h of contact time, TCs, fecal coliforms, and heterotrophic plate count were reduced by 78.2, 80, and 60%, respectively. Although RF efficiency in water disinfection has not been studied, our findings suggested its possible use due to more than 75% efficiency. From the standpoint of practical use, more studies should be done, especially to find a fine synergist agent, determining power, frequency, and suitable contact time and also the method should be modified.

Water scarcity and increasing demand for various applications has led to more attention to the treatment and using potential resources. Surface water is one of water resources in the societies. In the present study, the performance of two coagulants, Alum and Ferric chloride, was considered to determine turbidity, color, COD, and microbial reduction in the surface waters in Tehran.
Sampling was carried out from two surface waters named Sorkhehesar and Salehabad, during summer, fall, and winter. After optimization of coagulant dosage and pH, jar test experiments were conducted, and turbidity, COD, color, and microbial changes were considered.
Turbidity range in Sorkhehesar and Salehabad was between 91 and 500 NTU, and 35 to 400 NTU, respectively. Optimized dose of alum for summer, fall, and winter was 45, 100, and 35 mg/L, respectively, while in case of ferric chloride the optimized dose for three studied seasons was 5, 70, and 10 mg/L. Optimized dose of alum and ferric chloride in Salehabad, was determined as 28, 115, 2 and 30, 65, and 5 mg/L. Turbidity removal efficiency using both coagulants was higher than 95 percent, and color was totally removed in all experimented conditions.
From the stand point of turbidity, color, and COD removal both alum and ferric chloride showed the same results, however, ferric chloride dose was lower than alum. In case of turbidity removal alum showed higher removal efficiency, while for COD reduction upon the conditions, e.g. seasonal variation, alum and ferric chloride performance was not the same and was varied accordingly.