خيارات البحث
النتائج 51 - 60 من 4,895
Efficiency of Washing Techniques for Removal of Heavy Metals from Industrial Sludge
2019
J., Sumalatha | B. P., Naveen | R. K., Malik
The effluent treatment plant sludge is one of the major sources of contamination with toxic metals. Since the sludge contains heavy metals, it must be pretreated to reduce the contamination. The heavy metals from the sludge can be reduced/ separated by washing it with a suitable leaching solution. In the present study, the efficiencies of three leaching solutions to remove the contaminants from an industrial sludge were studied and the leaching process was modeled. The leaching solutions used are 0.1 N HCl, 0.1 N EDTA and 0.1 N FeCl3. The efficiencies of leaching solutions were assessed by conducting column leaching experiments on the sludge and the migration rates of heavy metal ions of Cu, Zn, Ni, Cd, Pb, Fe and Cr present in the sludge were estimated. These migration rates are useful to estimate the quantity of leaching solution required at the site to achieve the required levels of concentrations in the sludge.
اظهر المزيد [+] اقل [-]Investigation of Heavy Metal Contamination in the Surface Sediments of Anzali wetland in North of Iran
2019
Shariati, S. | Pourbabaee, A. A. | Alikhani, H. A. | Rezaei, k. A.
Over the last few decades, Anzali wetland has been at risk of pollutants, especially from heavy metals. The present research analyzes some physical and chemical properties and heavy metals concentration in 27 points in nine stations of Anzali wetland. The samples of each station have been mixed, acidic digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The mean concentrations of Fe, Mn, Pb, Zn, As, Cd, Cu, Hg, Ni, and Cr have been 50527.2, 1210, 23.3, 79.4, 8.8, 0.23, 32.1, 0.25, 31.6, and 31.5 mg/Kg, respectively. In addition, it can be seen that the concentrations of Cd (0.31 mg/Kg) and As (25.47 mg/Kg) in Hendekhale station, Hg (0.52 mg/Kg) in Pirbazar station, and Pb (52.69 mg/Kg) in Khazar villa station surpass world surface rock average. According to contamination factor (CF), in case of Mn and Pb, both Hendekhale, and Khazar Villa stations have been in considerable contamination level. The calculation of Pollution Load Index (PLI) shows that Hendkhaleh and Khazar Villa stations have had moderate pollution. The mCd index survey indicates that only in Hendekhale station, has heavy metals contamination been at a low degree level of contamination. According to PER index, mercury metal contamination in Hendekhale station faces medium risk. The calculated mean ERM quotient indicates the probability of heavy metals toxicity, equal to 21% in the examined stations.
اظهر المزيد [+] اقل [-]Influential Factors of Air Pollution Awareness in Isfahan, Iran
2019
Yazdanibakhsh, F. | Salehi, E. | Faham, E. | Amin, M. M.
The main objectives of the present study are to both evaluate the level of awareness about air pollution and examine the determinants, likely to affect this awareness. As a result, it discusses influential factors on air pollution awareness, presenting findings from a case study, conducted in the city of Isfahan, Iran, wherein 400 individuals have been selected via proportional random sampling and the data has been collected by means of a questionnaire, provided by the authors, the validity of which has been confirmed by a panel of experts. As for the assessment of the questionnaire’s reliability, this study has used Cronbach's alpha to find out that it has been beyond 0.7 for all variables. The data have been analyzed, using descriptive and inferential statistics, such as the extent of mean, standard deviation, the coefficient of variation, correlation analysis, and regression analysis. Results from the latter show that level of education, level of using information sources, membership, motivation, and participation could explain 50% of the variations in the level of awareness concerning air pollution.
اظهر المزيد [+] اقل [-]Estrous Cycle and Early Pregnancy of White Mice Exposed to Methomyl
2019
Toledo, J. M. | Gamalo, L. E. | Maligalig, M. D. | Suetos, K. J. | Galapon, M.
Methomyl is an oxime carbamate pesticide that is widely used in the Philippines. This insecticide is known to be an endocrine disrupting chemical and a potent genotoxic in mammalian cells. However, limited studies were conducted specifically on its direct effects on estrous cycle and its teratogenic effect. This study aimed to (a) assess the effect of methomyl on the body weight and on the estrous cycle of mice, and; (b) examine the teratogenic effect of methomyl on the progeny of the female albino mice. Five week-old experimental mice in three treatment setups were used in the study for both independent experiments. The treatment schedule for pregnant mice was administered during organogenesis (day 6 to 15 of gestation). Results showed that the average gained weight of the mice of both high dose (HD) and low dose (LD) groups were lower as compared to the average gained weight of the control group but did not show any statistical significant differences (p=0.562). For the experiment 1, methomyl significantly (p=0.013) affect the estrous cycle of the mouse especially in LD group. For experiment 2, results revealed that there was a significant difference among the treatment set-ups (p=0.0001) in terms of fetal morphometric measurement. Furthermore, abnormality and high number of resorption was also observed in both LD and HD treatment groups. Therefore, methomyl significantly affect the body weight, estrous cycle and fetal morphometry. This further confirm that methomyl is an endocrine disrupting and genotoxic chemical that affects the estrous cycle and causes teratogenic effect.
اظهر المزيد [+] اقل [-]Assessment of Contamination Potential of Leachate from Municipal Solid Waste Landfill Sites for Metropolitan Cities in India
2019
B. P., Naveen | R. K., Malik
With increased population, rapid industrialization and life style changes, the characteristics and the rates of solid waste generation have gone under drastic change in India. Generally, in India, management of solid waste landfill is of major concern with respect to the existing circumstances. The illegal dumping of municipal solid waste on the outskirts of cities is creating major environmental and public health problems. Improper and unscientific waste management results in potential threats from leachate leakage with subsequent impact on environment (i.e. soil, air and waterbodies) and human being. It is therefore, important to evaluate the contamination potential threat of landfill leachate. This study assesses the potential contamination from the landfill leachate by an index called leachate pollution index (LPI) and suggestions are given the landfill sites of five major cities i.e. Bangalore, Chennai, Delhi, Navi Mumbai & Kolkata in India. The landfill leachate samples from these sites have been assessed using leachate pollution index for the implementation of appropriate leachate treatment techniques for reducing the adverse effects on the environment. The results show that the Pallikkaranai landfill site for Chennai city and Mavallipura landfill site for Bangalore city are highly deteriorating and may lead to increase in human health risk for nearby dwellings.
اظهر المزيد [+] اقل [-]Efficient Removal of Methylene Blue from Aqueous Solution by Adsorption on Cerium Vanadate Nanoparticles
2019
Dehghan Abkenar, Sh. | Hosseini, M. | Sadeghpour Karimi, M. | Ganjali, M. R.
Cerium vanadate nanoparticles (CVNPs) were used as a solid phase adsorbent for removing methylene blue (MB) from aqueous media. The nanoparticles were obtained through a direct precipitation procedure in aqueous solutions, and were characterized by X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The results proved the product to comprise 25-45 nm particles. Batch adsorption experiments to determine the optimal adsorption conditions and the different factors which influence the adsorption efficiency (i.e. pH, amount of CVNPs, contact time, and the concentration of MB) were also evaluated. The experimental data were analyzed using the Langmuir and freundlich adsorption models.The data were satisfactorily fitted to the Langmuir model and a maximum adsorption capacity of 181.8 mg/g was obtained at pH of 3.0. Further kinetics studies were performed on the parameters. The adsorption of the model dye (MB) was found to reach equilibrium after 10 min, following a pseudo-second-order kinetic model. Desorption of the dye and recycling potential of the adsorbent was also studied.
اظهر المزيد [+] اقل [-]Assessment of Converter Sludge from Esfahan Steel Company as a Persulfate Nano-Activator for Permeable Reactive Barriers (Prbs) in Landfill Leachate Treatment
2019
Soubh, A. M. | Abdoli, M. A. | Baghdadi, M. | Aminzadeh, B.
The present research studies the performance of Converter Sludge (CL)as a nano-activator of persulfate (PS) in Permeable Reactive Barrier (PRB) as an in-situ technology for leachate treatment.In batch experiments, the acidic conditions (pH = 3) have been the most suitable for removal operations, where COD and NH3 removal efficiencies are 69.15% and 60.96%, respectively. The Box–Behnken design (BBD) has been employed to optimize three parameters, namely PS/ COD ratio, CS dose, and pore volume (PV), using COD and NH3 of leachate landfill as the target pollutant. The BBD is considered a satisfactory model to optimize the process. Under optimal conditions (PS/COD ratio: 3.47, CS dose: 3.09 g L-1,and PV: 4.27), the measured values of the COD and NH3 removal efficiencies have been 74.2 and 66.8, respectively, all within the 95%-prediction intervals, which indicate the model’s success in predicting removal values. The biodegradability (BOD5/COD) of the real leachate has been enhanced from 0.25 to 0.77, with the toxicity of real leachate getting decreased by more than 90%.
اظهر المزيد [+] اقل [-]A Multi-Metric Index for Hydrocarbons Source Apportionment
2019
Mahmudi, M. | Hashemi, S. H. | Salemi, A.
Several studies have been conducted to develop more accurate and precise indices for hydrocarbons source apportionment. The present study, however, develops a new multi-metric index for hydrocarbons source apportionment. It measures Poly Aromatic Hydrocarbons (PAHs) concentration at six stations with well known petrogenic origin, calculating Phe/An, Flu/Py, Chr/BaA, BaA/Chr, An/(An+Ph), Flu/(Flu+Pyr), and IP/(IP+Bghi) indices. All the indices could correctly determine the source of hydrocarbons, except for IP/(IP+Bghi). Subsequently, it uses principle component analysis method to create a combined multi-metric index, based on PAHs, the concentration of which also contributes to the evaluation of new index performance in stations with known origins. Results show that the new multi-metric index can determine the source of hydrocarbons with greater certainty. Then, using this index, the potential source of contamination in the area has been divided into six sections, namely HPY, MPY, LPY, MPE, HPE, and LPE, which indicate origin of high, moderate, and low risk of petrogenic contamination, as well as source of pyrolytic contamination with high, moderate, and low probabilities.
اظهر المزيد [+] اقل [-]The Study of CO Symptoms' Impacts on Individuals, Using GIS and Agent-based Modeling (ABM)
2019
jalali, S. H. | vafaeinejad, A. R. | aghamohammadi, H. | Esmaeili Bidhendi, M.
The purpose of this study is to use both agent-based modeling as a new method in modeling dynamic phenomena and GIS to show the effects of carbon monoxide (CO) on individuals in the city of Tehran. After collecting the latest information about the severity of carbon monoxide pollutants on different days, one of the days with a very high severity of this pollutant has been selected for investigation and the interpolation map of its data has been developed via IDW method in ArcGIS software environment, which is then re-classified with the NetLogo software environment used to run the agent-based model. At this stage, the agents are randomly produced in four different age groups in the environment and begin moving with the onset of the running process in the environment. Also, the symptoms, caused by the pollution effects on the agents, appear in form of changes in color and are based on carboxyhemoglobin (COHb) levels (percentage) of each. The results indicate that among the considered older age groups, the members of the age group above 65, have had been mostly affected by pollution and the effect of pollution on the agents of the age group of 13 to 30 years old has been less than the other groups.
اظهر المزيد [+] اقل [-]Application of Hybrid Cells in Series Model in the Pollution Transport through Layered Material
2019
Chabokpour, J.
The present paper aims at investigating the applicability of hybrid cells in the series model for pollution transport inside the layered porous media. For this purpose, four layers of rock material have fallen inside the experimental flume, with eight sensors installed longitudinally inside the media to obtain experimental BTCs. In order to measure time parameters of the model, named , two different methods of LSCF and MM have been examined. The model's sensitivity as well as its temporal equations with different parameters have been assessed. Finally, results show that at the fixed time step, the model is more sensitive to parameter (advection zone time parameter) rather than residential time parameters, to which the moment relations are more sensitive. A detailed computation of the related transport parameters has been operated and the Peclet number, crossing velocity, dispersion coefficient, time to the max, and maximum concentration have been calculated. Eventually, the model's applicability for large-scale porous media has been proven with only one unit of the cells.
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