Samira Abduolrahimi; Ali Akbar Safari Sinegani
Abstract
Background and purpose: Municipal and hospital waste land fills that have various contaminants, especially pharmaceuticals, provide a suitable habitat for resistant bacteria which play a special role in the transfer of resistance genes. Therefore, the abundance of microorganisms and the antibiotic resistance ...
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Background and purpose: Municipal and hospital waste land fills that have various contaminants, especially pharmaceuticals, provide a suitable habitat for resistant bacteria which play a special role in the transfer of resistance genes. Therefore, the abundance of microorganisms and the antibiotic resistance of bacteria in soil and leachate samples of municipal and hospital waste burial sites in Hamedan city were investigated.Materials and methods: The characteristics of soil and leachate as well as the abundance of their microorganisms were tested and counted. Also, the percentage of bacteria resistant to ten commonly used antibiotics ampicillin, amoxicillin, cefixime, gentamicin, streptomycin, tetracycline, doxycycline, chloramphenicol, lincomycin and metronidazole was investigated. In addition, the response of bacteria from two virgin soils and new rubbish landfill to different concentrations of three antibiotics, ampicillin, gentamicin and tetracycline, were measured.Results: The log of population of fungi, actinomycetes, pseudomonas, and enterobacters, was the highest in new rubbish landfill. They were 5.35, 5.28, 6.13, and 5.98 respectively. The percentage of bacteria resistant to all ten antibiotics was higher in samples of new rubbish landfill than in other locations and lower in virgin soil than in other locations. These results were also seen in the dose response of ampicillin, gentamicin and tetracycline antibiotics. The inhibitory concentrations of these antibiotics for new rubbish landfill bacteria were 1500, 1000 and 100 mg/l, respectively. But for virgin soil, they were much less (10, 18 and 50 mg/l respectively).Conclusion: In general, this research showed that municipal and hospital waste landfills provide a suitable habitat for antibiotic-resistant bacteria, which may increase the transfer of resistant genes among soil native bacteria. Therefore, the bacteria that reach the soil through waste can be more harmful.
Seyed Mostafa Tabatabaei; Ali Shahidi
Abstract
Abstract
Background & objeftive: In the Rafsanjan region of Kerman province, some sites have been considered for landfill construction. Since groundwater resources are the only source of water supply to provide water requirements in this region, the leachate leakage from landfills into groundwater ...
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Abstract
Background & objeftive: In the Rafsanjan region of Kerman province, some sites have been considered for landfill construction. Since groundwater resources are the only source of water supply to provide water requirements in this region, the leachate leakage from landfills into groundwater resources is regarded as a serious threat. The aim of this research is to study the trend of changes in the contamination concentration obtained from leachate leakage in a hypothetical landfill based on the geological and hydrogeological conditions of Rafsanjan plain in order to represent the effect of leachate leakage and contamination spread on groundwater resources.
Methods and Materials: Transmission of contamination has been studied on the basis of changes in concentration at two initial and final points of landfill by MT3DMS model daily and for 22 years period. The concentration of leachates has been considered 2 and 4 g / l, and its diffusion rate has been assumed 1.5 and 3 cm per day.
Results: The slope of the concentration increase in the propagation process and delayed diffusion at the beginning of the landfill with 2 and 4 g/l concentration and 1.5 cm rate during 15 and 17 years have an increasing trend, respectively and later it would have a decreasing trend. At the end of landfill, 90% increase in contamination will occur for 2 g/l concentration in the first five years and 4 g/l concentration in the first 9 years and it will have a fixed trend over the next few years.
Conclusion: In the various transmission processes after the penetration of the infection into the aquifer, the concentration of contamination is initially low and increasing over time and if the concentration of the contamination penetrating source and penetrating intensity are constant, the maximum concentration of aquifer pollution is fixed at a certain value. The type of transmission process has a huge impact on this constant value. So that in the propagation-diffusion process, the average in the first 5 years of this value is fixed and in a delayed state, it reaches a constant value after close to 22 years.
kazhal kakaei; Ali reza Riyahi Bakhtiari; Mahdi Gholamali fard
Abstract
Background and purpose: Infiltration of leachate produced by municipal solid waste into the ground water poses a serious environmental hazard due to its high content of hydrocarbons and heavy metals. The leachate is the primary source of soil and water pollution. In this paper the risk of heavy metals ...
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Background and purpose: Infiltration of leachate produced by municipal solid waste into the ground water poses a serious environmental hazard due to its high content of hydrocarbons and heavy metals. The leachate is the primary source of soil and water pollution. In this paper the risk of heavy metals discharged from leachate in to groundwater in Hamadan landfill has been assessed using Industrial Waste Management Evaluation Model (IWEM). Methods: The concentrations of heavy metals (Cu,Pb,Ni and Cd) in leachate were determined by atomic absorption spectrophotometry and the risk of these metals discharge into groundwater was assessed by IWEM using Monte Carlo analysis. Results: Based on the obtained IWEM and EPACMTP results, geosynthetic cover was recommended for this matter. Conclusion:The most appropriate option for groundwater protection in Hamadan landfill was recommended to be geosynthetic cover (Composite linear). Owing to the high probability of leachate infiltration into groundwater, there is need to be made stricter management decisions in this regard. Also, it is necessary that IWEM is used for prevention of leachate infiltration into groundwater.
Elahe Rezaie; Mahdi Sadeghi; Ghodratollah Shams Khoramabadi
Abstract
Background and objective: One of the major environmental problems of municipal landfill is leachate. Electrochemical methods are considered for the treatment of leachate. This study aimed at the treatment of landfill leachate electrochemical method using a platinum electrode and graphite based on a laboratory ...
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Background and objective: One of the major environmental problems of municipal landfill is leachate. Electrochemical methods are considered for the treatment of leachate. This study aimed at the treatment of landfill leachate electrochemical method using a platinum electrode and graphite based on a laboratory scale. Materials & Methods: In this study, the equipment for electrochemical reactor included an anode electrode made of platinum and a cathode electrode made of graphite. Chromium and organic matter removal percentage in the electric current density range of 1, 2, 3, 4 A and reaction time of 1, 2, 3, 4, 5, 6, 7, and 8 hours were surveyed. Results: The results showed that electrical coagulation process can increase removal of organic matter and heavy metals and by increasing the time the removal of COD and BOD and chromium will increase. Meanwhile, the rate of degradation wills elevates. By increasing the intensity of electric current, the time required to achieve the same removal efficiency is reduced and by reducing the amount of electrical current, the required time increases. Conclusion:The results indicated that electrochemical process, by using a platinum electrode and graphite is a method for treating wastewater containing heavy metals, BOD and COD .Elerochemical process as a pre-treatment process can remove organic matters, heavy metals. It also reduces the organic load and increases the degradation of sewage. The method can be used as an effective option for the treatment of sewage, prevention of environmental pollution, and protection of water supplies.