فهرست مطالب

  • Volume:8 Issue: 1, 2020
  • تاریخ انتشار: 1399/01/26
  • تعداد عناوین: 8
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  • Ahmad Badeenezhad, Iman Parseh *, Behnaz Mohamadi Asl, Omid Azadbakht, Mehrab Sayadi Pages 1-9
    The microbial quality of water plays a key role in community health. The present study aimed to determine the microbial quality of the drinking water distribution networks in the urban and rural areas of Dasht-e Azadegan County, Iran and assess the influential factors in the quality of drinking water.In this descriptive-analytical study, 907 drinking water samples were collected from the urban and rural regions in Dasht-e Azadegan County in 2017. Turbidity, free residual chlorine, pH, total coliforms, and fecal coliforms were measured using the Standard Methods for the Examination of Water and Wastewater, and the results were analyzed using the logistic regression model. The free residual chlorine was within the range of 0-3 mg/L (mean: 0.72 mg/L). The free chlorine residual in 58% of the samples was within the recommended range of the World Health Organization (WHO) for drinking water, and 29% of the samples had higher turbidity than the accepted limit of the WHO (5NTU). In addition, 7.7% and 16% of the samples were infected with fecal and total coliforms, respectively. According to the results of the logistic regression analysis, coliform contamination was most significantly associated with free chlorine residual and turbidity, and reduced free chlorine residual was most effective in coliform contamination.
    Keywords: Dasht-e Azadegan, Drinking Water, logistic regression, Microbial Quality
  • AmirHossein Baghaie *, Aminollah Aghilizefreei Pages 10-18

    The present study aimed to investigate the effects of salicylic acid (SA), humic acid (HA), and EDTA chelate on the increasing Pb concentration in a plant inoculated with plant growth-promoting rhizobacteria (PGPR). Treatments consisted of applying two levels of EDTA (0 (EDTA0) and 3 (EDTA3) mmol/kg soil) and soil application of HA (0 (HA0) and 200 (HA200) mg/kg soil). In addition, foliar application of SA at the rates of 0 (SA0) and 1.5 (SA1.5) mmol/lit was also sprayed on the inoculated plant with and without PGPR cultivated in the Pb-polluted soil. After 9 weeks, barley plants were harvested and plant Pb concentration was measured using atomic absorption spectroscopy (AAS). The soil Pb concentration and plant Pb biomass was also measured. The least significant difference (LSD) test was used to determine the differences between the means (P=0.05). The results indicated that application of HA or EDTA had significantly (P=0.05) increased the Pb phytoremediation efficiency, as, applying 3 mmol EDTA/kg soil increased the Pb phytoremediation efficiency by 14.1%. In addition, a significant increasing (P=0.05) in plant biomass and Pb phytoremediation efficiency was observed by 12.2 and 13.6%, respectively, in the inoculated plant cultivated in the soil that received the greatest rates of EDTA and HA together with the highest rate of SA foliar application. Plant growth regulators such as SA or humic acid can increase plant resistance to Pb toxicity and help to increase Pb phytoremediation efficiency that is important in environmental studies.

    Keywords: Phytoremediation, Pb, Plant biomass, Humic acid
  • Roya Ebrahimi, Bagher Hayati, Reza Rezaee, Behzad Shahmoradi, Mahdi Safari, Shivaraju Harikaranahalli Puttaiah, Afshin Maleki * Pages 19-24
    Numerous heavy metals such ascadmium and nickel are toxic present in industrial wastewater and could cause severe damage to living organisms. These compounds are considered to be common contaminants, which are discharged into water resources and cause major environmental problems. Due to the excessive toxicity of heavy metals even at low concentrations, they also threaten human health. Therefore, it is essential to remove these elements from wastewater before discharge into the environment. The present study aimed to evaluate the adsorption of cadmium and nickel from aqueous solutions using poly (propyleneimine) (PPI) dendrimer, as well as the influential factors such as pH, PPI dosage, and the initial concentration of cadmium and nickel using a batch model. To assess the mechanism of adsorption and calculate the maximum adsorption values, the Langmuir and Freundlich isotherms were used. The findings indicated that increased pH and adsorbent dosage improved the removal efficiency. In contrast, increased heavy metal ion concentrations decreased the adsorption. According to the dynamic light scattering analysis, the mean diameter of the PPI dendrimer was 1-10 nm, and the maximum adsorption of both heavy metal ions occurred at the pH of seven. In addition, the maximum uptake of cadmium and nickel was attained with the adsorbent dosage of 0.08 g/l. The maximum removal capacities of the PPI dendrimer for nickel and cadmium were estimated at 1,428 and 1,225 mg/g, respectively.
    Keywords: Adsorption, Cadmium, nickel, Dendrimer
  • Azam Mehdipour, Mojgan Zaeimdar *, MohammadSadegh Sekhavatjou, SayedAli Jozi Pages 25-38

    Tehran is a polluted metropolitan and the capital of Iran, where heavy traffic and excessive energy consumption (especially gasoline) are the major sources of heavy metal emissions. This study aimed to investigate the variations in heavy metal concentrations on the aerosols of the outdoor and indoor environments in the high-traffic regions of Tehran. This was a descriptive, applied research in terms of methodology. Six internal-external stations were specified in three high-traffic regions. Sampling was performed in six replications for each station during fall 2018(n=36). After the extraction of the heavy metals from the fiberglass filters using acidic digestion based on the ASTM method, their concentrations were measured via ICP-OES. Data analysis was performed in SPSS using MANOVA. According to the results, regions 2, 3, and 15 had the highest traffic in Tehran during the study, with the traffic rate estimated at 25-27% hours per day on average. A significant difference was observed between the outdoor and indoor regions in terms of heavy metal concentrations (P<0.05). The order of the mean concentrations of heavy metals in the open spaces was as follows: Al>Fe>Pb>Mn>Cu>Zn>Cr>As>Ni>Cd. Aluminum and cadmium had the highest and lowest concentrations, respectively. In addition, the high concentration of lead and heavy traffic was alarming in Afsariyeh Street (region 15). Considering the adverse effects of pollution on the health of citizens, serious measures should be taken to control traffic in Tehran.   Keywords: Heavy metals, Traffic volume, Tehran metropolitan, Indoor and outdoor environment

    Keywords: heavy metals, Traffic volume, Tehran metropolitan, Indoor, outdoor environment
  • Majid Hashemi, Nastuna Ghanbari Sagharlo * Pages 39-48
    The adverse health effects of trinitrotoluene (TNT) include allergies, liver and blood damage, and carcinogenesis. The present study aimed to optimize the sono-Fenton and photo-Fenton processes for the removal of TNT from aqueous solutions. TNT removal was evaluated at various pH (acidic, neutral, and alkaline), pollutant concentrations (10, 30, 50, 100, and 120 mg/l), H2O2 concentration (10-80 mM), and ferrous ions (0.5-4 Mm). After the optimization of the parameters, the appropriate UV irradiation time and optimal time of ultrasonic waves were determined for the removal of this compound. TNT concentration was measured using high-performance liquid chromatography. Increased hydrogen peroxide from 10 to 40 mMole/l led to higher TNT degradation (45.3% to 88.4% and 40 to 80 mMole/l), while the removal rate decreased from 88.4% to 79%. At the optimal H2O2 concentration, increased pH (3±0.2 to 11±0.2) decreased TNT decomposition from 88.4% to 23.5%. In addition, increased time (5 to 60 minutes) led to the higher photo-Fenton process efficiency (68.6% to 89%). The maximum photo-Fenton efficiency was achieved in optimal conditions at the TNT concentration of 10 mg/L (97%) and 60 minutes, while the efficiency of the sono-Fenton process in optimal conditions was 100% at 20 minutes. Therefore, it was concluded that the sono-Fenton process was effective in the removal of TNT.
    Keywords: hydroxyl Radical, Trinitrotoluene, Water resources, Ultrasonic waves, UV Radiation
  • Anwuli U. Osadebe *, Blessing Okounim Pages 49-58
    Dissemination of antibiotic resistance via aquatic systems is considered to be an important environmental health concern. The present study aimed to assess the levels of multidrug-resistant bacteria in the raw wastewater of two hospitals in Port Harcourt metropolis using standard microbiological techniques. Among 64 bacterial isolates, seven bacterial groups were identified, including Klebsiella pneumoniae, Escherichia coli, Enterobacter, Staphylococcus aureus, Citrobacter, Shigella, and Bacillus. The bacterial counts were within the ranges of 7.8 x 104-4.8 x 106 and 6.9 x 104-1.09 x 105 CFU/ml in hospitals A and B, respectively. The obtained results indicated high resistance to quinolones/fluoroquinolones (83.3-90%) and penicillins (50-70%). In addition, 86.9% of the isolates showed multidrug resistance. The multiple antibiotic resistance (MAR) index was within the range of 0.1-0.8 in the gram-positive bacteria and 0.1-0.6 in the gram-negative bacteria. The findings confirmed the presence of bacteria with high MAR indices in the untreated hospital wastewater.
    Keywords: Antibiotic Resistance, Bacteria, environmental health, Pollution, Wastewater, Water Quality
  • Mahboub Saffari *, Fatemeh Hajizadeh Khanamani Pages 59-72
    The present study aimed to evaluate the effects of titanium dioxide nanoparticles (T: 1 and 3%), sheep manure biochar (B: 1 and 3%), and their combination (T0.5% + B0.5% and T1.5% + B1.5%) on the degradation/sorption of methylene blue (MB: 100, 200, and 300 mg/kg soil) in sandy loam (SL) and loam (L) soils with variable light radiation (ultraviolet(UV) and visible(VS)). According to the results, the application of T (especially with UV radiation exposure), B, and their combination significantly reduced the MB concentration in the soils compared to the control treatment (without T and B). In addition, the combined application of T and B (T1.5% + B1.5%) was significantly more efficient than the other treatments in the reduction of the MB extraction in the studied soils. However, B and T application decreased the soil MB concentration, but due to the competition between the ions in the soils and MB for adsorption on the B and T surfaces, insufficient water in the soils to form appropriate amounts of degradable hydroxyl radicals, low absorption of UV radiation by T (due to the high thickness of the soil layer), and consumption of large amounts of T for soil organic matter degradation, the efficacy of these amendments decreased. Moreover, lack of using specialized biochar for this cationic contaminant (modification of the B functional groups) diminished the efficiency of this adsorbent in the soil, which requires further investigations.
    Keywords: Titanium dioxide nanoparticles, Biochar, Methylene blue, Soil, Ultraviolet
  • Arman Yousefi, Zahra Hojjati Bonab * Pages 73-84
    Lack of access to safe drinking water is an important health concern in developing countries. The present study aimed to investigate the microbial and physicochemical quality of the drinking water storage tanks and distribution networks in the villages of Saqqez in Kurdistan province, Iran in the summer of 2018. This descriptive, cross-sectional study was conducted by sample collection from the storage tanks and distribution networks in 20 villages covered by Saqqez Rural Water and Wastewater Company during three months. Chemical tests were performed based on titration, and physical tests were carried out using instrumental methods. The culture of the specimens was performed to determine the total and fecal coliforms using the most probable number (MPN method. Data were analyzed in SPSS and Excel software. In 100% of the storage tank samples, total and thermophilic coliforms were within the national and international standards. In the distribution networks, 11.67% and 33.3% of the samples had higher total and thermophilic coliforms than these standards, respectively. The residual chlorine parameter was higher than the national standards in 15% of the storage tank samples and 25.03% of the distribution network samples. Turbidity, total hardness, chloride, electrical conductivity, pH, and TDS in the storage tanks and distribution networks were in accordance with the national and international standards. All the physical and chemical parameters (except for chlorine residues) were within the national and international standards, and the maximum total and fecal coliforms were six MPN, which could be maintained in the standard range via chlorination.
    Keywords: Total Coliform, Fecal coliform, Drinking Water, storage tanks, Distribution Networks