فهرست مطالب
Environmental Health Engineering and Management Journal
Volume:2 Issue: 2, Spring 2015
- تاریخ انتشار: 1394/03/17
- تعداد عناوین: 8
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Page 47BackgroundAminoglycoside antibiotics are widely used in medical centers, particularly to treat infections. The resistance developed against these agents is a huge concern in health care. A number of researchers have reported that hospital and municipal wastewaters are among the most important dissemination sources of these agent into the environment. Some, however, do not agree with this opinion. In the present study, the prevalence of aminoglycoside resistance genes was investigated in raw and effluent wastewater from hospital and municipal wastewater treatment plants.MethodsTo conduct this descriptive-analytical study, 30 samples were taken according to sampling principles and cold cycle and transferred to the molecular laboratory. DNA was extracted by the freeze-thaw method using a kit (Promega). The genes aac(3)-IIa and aac(6’)-Ib which code aminoglycoside resistance were examined in this study.ResultsThe results indicated that the studied genes are present in 35% of urban and hospital wastewaters, and their frequency percentage is higher in hospital wastewater (52%) than urban wastewater (48%). The studied genes were identified in 61% of raw hospital wastewater samples; however, they were not detected in the output wastewater from the studied treatment plants.ConclusionAlthough, the studied genes were not detected in the final effluent, there is a high potential for their release into the environment. The current study demonstrated that the coding genes of aminoglycoside antibiotic resistance are present in raw urban and hospital wastewaters. In the case of improper exploitation of wastewater treatment plants, the output water can contaminate other environmental sections, such as soil and water resources, and result in the emission of these contaminants.Keywords: Antibiotic resistance, Aminoglycosides, Urban, hospital wastewaters
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Page 53BackgroundNatural organic matter is the cause of many problems associated with water treatment such as the presence of disinfection by-products (DBPs) and membrane fouling during water filtration. In this study, the performance of the peroxi-electrocoagulation process (PEP) was investigated for the removal of humic acids (HAs) from aqueous solutions.MethodsPEP was carried out for the removal of HA using a plexiglas reactor with a volume of 2 L and fitted with iron electrodes and a direct current supply (DC). Samples were taken at various amounts of pH (2-4), current density (1 and 2A/cm2), hydrogen peroxide (50-150 mg/L) and reaction time (5-20 minutes) and then filtered to remove sludge formed during reaction. Finally, the HA concentration was measured by UV absorbance at 254 nm (UV254).ResultsResults indicated that increasing the concentration of H2O2 from 50 to 150 mg/L increased HA removal efficiency from 83% to 94.5%. The highest removal efficiency was observed at pH 3.0; by increasing the pH to the alkaline range, the efficiency of the process was reduced. It was found that HA removal efficiency was high in current density 1A/cm2. Increasing current density up to 1 A cm-2 caused a decrease in removal efficiency. Results of this study showed that under the optimum operating range for the process ([current density] = 1A/cm2, [hydrogen peroxide concentration] = 150 mg/L, [reaction time]= 20 minutes and [pH]= 3.0), HA removal efficiency reached 98%.ConclusionIt can be concluded that PEP has the potential to be utilized for cost-effective removal of HA from aqueous solutions.Keywords: Humic acid, Peroxi, electrocoagulation, Iron electrode, UV254, Water solutions
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Page 59BackgroundSuccessful waste management programs are linked to internal factors, SW (strength and weakness points), and external factors, OT (opportunities and threats), and at the macro level are grounds for sustainable development. Studies may be related to David’s study which presented a method to quantify strength, weakness, opportunity, threats (SWOT) analysis.MethodsIn this study, designed to investigate recycling and managing dry residues in District 1, threat factors were studied and internal factors evaluation (IFE) and external factors evaluation (EFE) matrixes were scored. Tehran Municipality District 1 has 10 subdistricts and 26 neighborhoods. The dry residues from Municipality District 1 that currently weigh approximately 2678 tons per day.ResultsResults showed that WO strategies for improving weaknesses and employing opportunities available in District 1 are ideal. After constructing the Quantitative Strategic Planning Matrix (QSPM), WO strategies were prioritized.ConclusionThe evaluation matrix of internal and external factors in the city of Tehran indicated that waste management has weak internal factors. Meanwhile, evaluation points of external factors showed that, in the current situation, SWOT could achieve good results. Waste management systems are involved with different multi-disciplinary factors; therefore, trends in the development of waste treatment technologies have been led by various social, economic, and environmental drivers in Tehran.Keywords: Solid waste management, SWOT, Strategic management
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Page 67BackgroundThis study aimed to evaluated trends for iron and manganese concentrations in wells, reservoirs, and water distribution networks in Qom city during the summer of 2012.MethodsThis was a cross-sectional study. The studied scopes consisted of groundwater (60 wells), reservoirs (10 tanks), and water distribution network (33 points). One sample was taken from each source monthly. Statistical tests used included post hoc tests (Tukey HSD). Finally, the results were compared with drinking water standards.ResultsThe average concentrations of iron in groundwater, reservoirs, and distribution networks were 0.09, 0.07, and 0.07 mg/l, respectively. The average concentrations of manganese in groundwater, reservoirs, and distribution networks were 0.15, 0.09, and 0.1 mg/l, respectively. The turbidity averages in groundwater, reservoirs, and distribution networks were 0.58, 0.6, and 0.52 NTU, respectively. The average concentrations of free chlorine residual in water reservoirs and distribution networks were 1.74 and 1.06 mg/l, respectively. The pH averages in groundwater, reservoirs, and distribution networks were 7.4, 7.7, and 7.5, respectively. The amounts of iron, manganese, turbidity, free chlorine residual, and pH in the investigated resources had no significant differences (P > 0.05).ConclusionThe amounts of iron, manganese, turbidity, free chlorine residual and pH in groundwater, reservoirs, and water distribution networks of Qom are within permissible limits of national standards and EPA guidelines. Only the amount of manganese was higher than the Environmental Protection Agency (EPA) permissible limit.Keywords: Iron, Manganese, Drinking water, Qom
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Page 87BackgroundThe effective size of the end grain of horizontal roughing filters (HRFs) is larger than 2 mm. This study aimed to examine the efficiency of HRFs in removing nitrate, phosphate, and chemical oxygen demand (COD) from effluent of a wastewater stabilization pond.MethodsThis experimental study was conducted in 2013. The pilot project was transferred to the Karaj wastewater treatment plant (stabilization pond), and the installation, equipping, and start-up of the system began using an effluent treatment plant. Sampling was done from March to August in 3 rates, 0.5, 1 and 1.5 m/h, and included simultaneous sampling from inlet and outlet filtering to determine the concentrations of nitrate, phosphate, and COD.ResultsAt filtration rates of 0.5, 1, and 1.5 m/h, the average nitrate removal equaled 25%, 32%, and 34%, respectively, average phosphate removal equaled 29%, 26%, and 28%, respectively, and the average COD removal at filtration rates of 0.5, 1, and 1.5 m/h equaled 62%, 66%, and 68%, respectively. Outlet values of phosphate and nitrate were lower than the standards set by the Environmental Standards Organization (ESO) (P < 0.05).ConclusionAccording to the results of this study, the HRF function was approximately adequate in COD removal, but its efficiency in nitrate and phosphate removal was lower.Keywords: Wastewater stabilization pond, Horizontal roughing filter, Nitrate, Phosphate, Chemical oxygen demand
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Page 93BackgroundIn 2007, a rule prohibiting the use of incinerators was ratified by the Iranian Islamic Parliament. Based on this rule, the Ministry of Health emphasized the sterilization of infectious waste at its production source by means of non-incineration equipment and methods. This research examined the performance of non-incineration technologies in treating medical infectious and sharps wastes at educational hospitals affiliated with Shahid Beheshti University of Medical Sciences.MethodsThis cross-sectional descriptive study was conducted in 12 educational hospitals of Shahid Beheshti University of Medical Sciences. First, a questionnaire was designed and its validity approved. Then the required data was gathered during visits to participating hospitals. Finally, the collected data were analyzed using Microsoft Excel and SPSS version 16.ResultsFindings showed that the daily production of infectious and sharps wastes in the studied hospitals generally equaled 3387 kg. All hospitals were equipped with non-incineration systems; however, only 83.3% of them were active. Some infectious waste was disposed of along with urban wastes without being sterilized. Monthly biological assessments of treatment equipment were implemented for only 41.7% of the equipment.ConclusionThe failures of the non-incineration systems demand that appropriate investigations be conducted prior to the purchase of these devices. Monthly biological assessments are essential to ensure the accuracy of the systems’ performance in hospitals.Keywords: Waste treatment, Non, incineration technologies, Infectious waste, Sharps waste, Hospital