细化搜索
结果 21-30 的 4,935
Impact of Hindon River Water on Selected Riparian Flora (Azadirachta Indica and Acacia Nilotica) with special Reference to Heavy Metals 全文
2019
Ruhela, M. | Bhutiani, R. | Ahamad, F. | Khanna, D.R.
The present study aims to identify the impact of polluted aquatic body i.e. River Hindon on two selected riparian flora i.e. Azadirachta indica and Acacia nilotica. During the course of study the average concentration of different metals in river water was found as Iron (Fe) 11.27ppm±3.50, Manganese (Mn) 4.00ppm±1.26, Cadmium (Cd) 0.08ppm±0.07, Nickel (Ni) 0.63ppm±0.17 and Zinc (Zn) 1.46ppm±0.38 respectively. The average concentration of heavy metals in A. indica of sampling site was found as Iron (Fe) 24.76ppm±6.25, Manganese (Mn) 5.04ppm±1.38, Cadmium (Cd) 0.05ppm±0.05, Nickel (Ni) 0.34ppm±0.20 and Zinc (Zn) 53.92ppm±19.29 respectively while in control site plant average concentration was found as Iron (Fe) 17.18ppm±3.96, Manganese (Mn) 3.63ppm±1.63, Cadmium (Cd) 0.02ppm±0.03, Nickel (Ni) 0.16ppm±0.06 and Zinc (Zn) 31.26ppm±12.11 respectively and average concentration in A. nilotica of sampling sites was found as Iron (Fe) 45.78ppm±10.67, Manganese (Mn) 42.08ppm±11.98, Cadmium (Cd) 0.59ppm±0.51, Nickel (Ni) 40.83ppm±12.16 and Zinc (Zn) 144.10ppm±49.94 respectively while average concentration in control site plant was found as Iron (Fe) 27.76ppm±9.49, Manganese (Mn) 22.75ppm±7.09, Cadmium (Cd) 0.42ppm±0.27, Nickel (Ni) 23.53ppm±8.02 and Zinc (Zn) 96.61ppm±24.78 respectively. One way ANOVA shows statistically significant difference between sampling site plant and control site plant for all the studied metals except Cr in A. nilotica F (3, 42) = 0.589, P= 0.626. A big difference was found in the concentration of metals between sampling site plants and control site plant. In case of metal uptake A. nilotica was found more efficient as comparison to A. indica.
显示更多 [+] 显示较少 [-]A Review on Impact of E-waste on Soil Microbial Community and Ecosystem Function 全文
2019
Salam, M.D. | Varma, A.
The ever increasing pile-up of electronic waste in dumping sites, especially in developing countries such as China, Pakistan, India and several African countries, might have caused a significant alteration in the microbial community of the contaminated sites. This change in the microbial population may have significant impact to the soil ecology function. The major pollutants of electronic waste are heavy metals like cadmium, lead, nickel, mercury, hexavalent chromium, arsenic and persistent organic pollutants like polychlorinated biphenyls and polybrominated diphenyl ethers. In general, the toxic pollutants reduce the normal soil microbial biota but give rise to increase in the heavy metal resistant and organic pollutants remediating microbes. With the development of culture- independent approach as a tool for studying microbial diversity, the microbial community structures in toxic waste contaminated sites have been revealed gradually. Studies on the microbial community structure of electronic waste contaminated sites show that there are significant differences between the contaminated and the non-contaminated sites. Soil pH in the e-waste contaminated sites of various regions has been reported in a wide range varying from pH 4 to pH 12. However, the predominant phyla so far identified in the electronic waste contaminated sites, based on studies through culture independent approach, are Firmicutes, Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Crenarchaeota and Bacteroidetes accounting for more than 80% of the total sequence reads on an average. The genera like Pseudomonas, Bacillus, Clostridium, Rhodococcus, Achromobacter and many unclassified bacteria are the common types in the contaminated sites.
显示更多 [+] 显示较少 [-]Lake Hydro Geochemistry: An Implication to Chemical Weathering, Ion-exchange Phenomena and Metal Interaction 全文
2019
Dutta, G. | Gupta, S. | Gupta, A.
Present study aims to unravel the hydro geochemical interaction of sediment and water of Saheb bandh lake, West Bengal, India with an emphasis on heavy metal assessment. Lake water belongs to Ca2+–HCO3− type hydro geochemical faces and water-rock interaction primarily controls the lake water chemistry. Based on different Hydro chemical characteristics it is suggested that silicate weathering is the major hydro geochemical process operating in Saheb bandh lake water. Regarding point source contribution of pollutants the average value of NO3-N, TP and Hg are much higher in inlet water (7.5 mg/L, 1.29 mg/L and 8.5 μg/L) than the lake water (1.5 mg/L, 0.05 mg/L and 0.42 μg/L). Risk assessment indices suggest advanced decline of the sediment quality. Water-sediment interaction of heavy metals reveals that Cd, As, Pb and Hg metals enter into lake water as a result of not only natural processes but also of direct and indirect activities of humans. This study recommends that continuous monitoring of these metals in water and sediment and other aquatic biota of Saheb bandh should be directed to assess the risk of these vital heavy metals in order to maintain the safe ecology in the vicinity of this lake.
显示更多 [+] 显示较少 [-]Performance Comparison of Predictive Controllers in Optimal and Stable Operation of Wastewater Treatment Plants 全文
2019
Hasanlou, H. | Torabian, A. | Mehrdadi, N. | Kosari, A. R. | Aminzadeh, B.
Any proper operation could be translated as a constrained optimization problem inside a WWTP, whose nonlinear behavior renders its control problems quite attractive for performance of multivariable optimization–based control technique algorithms, such as NMPC. The main advantage of this control technique lies in its ability to handle model nonlinearity as well as various types of constraints on the actuators and state variables. The current study presents the process of BSM1 building, step by step, proposing appropriate numerical methods are creating the simulation model in MATLAB environment. It also makes a detailed comparison of the proposed NMPC with five recent predictive control schemes, namely LMPC, hierarchical MPC+ff, EMPC, and MPC+fuzzy, along with the default PI. The performance of predictive control schemes is much better than the default PI; however, something of highest importance is the ability to use the proposed control scheme in real systems, for a real application faces several limitations, especially in terms of the equipment. Finally, in order to compare predictive controllers, it is necessary to determine the same conditions so that results from more days can be used, and, if needed, more than 28 days have to be simulated. MOI index can help determine which of the proposed control scheme is really applicable.
显示更多 [+] 显示较少 [-]Amino Functionalized Silica Coated Fe3O4 Magnetic Nanoparticles as a Novel Adsorbent for Removal of Pb2+ and Cd2+ 全文
2019
Saadat, A. | Hajiaghababaei, L. | Badiei, A. | Ganjali, M. R. | Mohammadi Ziarani, G.
The present study synthesizes a novel adsorbent by coating Fe3O4 magnetic nanoparticles with amino functionalized mesoporous silica. The FTIR spectrums indicate that silica has been successfully coated on the surface of Fe3O4 and 3-aminopropyl tri methoxysilane compound have been grafted to the surface of silica-coated Fe3O4. The XRD analysis shows the presence of magnetite phase with cubic spinel as a highly crystalline structure, before and after silica coating. The study also investigates the potentials of amino functionalized silica-coated Fe3O4 magnetic nanoparticles for extraction of Pb2+ and Cd2+ cations from aqueous solutions, where it has used flame atomic absorption spectrometry to determine ion concentration in both recovery and sample solutions. The optimum conditions of removal of Pb2+ and Cd2+ ions turn out to be pH= 4-8 with a stirring time of 20 minutes. The minimum amount of 3M nitric acid to strip ions from functionalized magnetic nanoparticles is 10 mL. The experimental data show the adsorption isotherms have been well described by Langmuir isotherm model, with the maximum capacity of the adsorbent being 1000.0 (± 1.4) μg, 454.5 (± 1.6) μg of Pb2+, and Cd2+ per each mg of functionalized magnetic nanoparticles, respectively. Finally, the proposed adsorbent is successfully applied to remove Pb2+ and Cd2+ ions in wastewater samples.
显示更多 [+] 显示较少 [-]Evaluation of Catalytic Effects of Metal Oxide Nanoparticles on Pyrolysis of Used Lubricating Oil 全文
2019
Alavi, S. E. | Abdoli, M. A. | Khorasheh, F. | Bayandori Moghaddam, A.
Pyrolysis is an applicable method that has been widely used to recover hydrocarbons from Used Lubricating Oil (ULO). However, large-scale application of this approach has been limited by its noticeably energy and time consuming nature. In the present research, it has been attempted to modify the energy and time requirements of ULO pyrolysis using the catalytic effects of metal oxide nanoparticles (NPs). The impacts of γ-Al2O3, γ-Fe2O3 and ZnO NPs on the kinetic features of ULO pyrolysis were studied using thermogravimetric analysis (TGA). The kinetic parameters of the pyrolysis process were calculated based on Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozava (FWO) models. The activation energy of virgin ULO pyrolysis had been calculated to be 161.505 and 162.087 kJ/mol using KAS and FWO models, respectively. However, in the present work, utilization of γ-Fe2O3 NPs significantly reduced the activation energy of ULO pyrolysis to 133.511 and 138.289 kJ/mol through KAS and FWO models, respectively. The catalytic effect of ZnO NPs was not as noticeable as that of γ-Fe2O3 NPs, resulting in activation energies of 155.568 and 158.501 kJ/mol using KAS and FWO models, respectively. Moreover, based on the results of this study, γ-Al2O3 NPs had no significant impact on the kinetics of ULO pyrolysis.
显示更多 [+] 显示较少 [-]Characteristics and Health Risk of BTEX at Selected Different Microenvironments in an Industrial-Urban Area, Iran 全文
2019
Tarassoli, A. | Esmaili Sari, A. | Bahramifar, N.
The present study monitors BTEX concentration in outdoor and indoor air of eight different microenvironments during summer 2017 and winter 2018 at Asaloyeh city, Iran's energy capital. It samples BTEX compounds by charcoal tubes, analyzing the samples by means of a gas chromatograph with a flame ionization detector. According to the obtained results, outdoor concentrations of BTEX have been higher than the indoor ones, for both seasons, with the highest outdoor and indoor BTEX being 21.70 and 18.59 μg/m3, respectively. Toluene has been the most abundant substance, among the investigated BTEX in all sampling points. Based on the MIR scale, m, p-xylene is the most dominant contributor to ozone formation potential among BTEX species. Indoor to outdoor (I/O) ratios of BTEX compounds range from 0.53 to 0.88 and 0.41 to 0.77 in winter and summer, respectively. The cumulative hazard index (HI) is within an acceptable range. The LTCR value of benzene concentration, obtained, exceeds the value of 1.0E-06, recommended by USEPA. Sensitivity analysis shows that benzene concentration, exposure duration, and inhalation rate have a greater impact on health risk assessment.
显示更多 [+] 显示较少 [-]Extraction and Recovery of Polycyclic Aromatic Hydrocarbons in Petroleum Contaminated Soils Using Supercritical Water by Response Surface Methodology 全文
2019
Motamedimehr, Sh. | Gitipour, S.
Finding an environment-friendly and affordable method to remove contaminated soils from Polycyclic Aromatic Hydrocarbons (PAHs) has now become an attractive field for researchers, with super-critical fluid extraction being an innovative process in the field of contaminated soil treatment. Extraction with super-critical fluid is a simple and rapid extraction process that uses super-critical fluids as solvents. The present study has investigated the extraction of contaminated soil with Polycyclic Aromatic Hydrocarbons (PAHs) by means of batch supercritical water reactor, employing variables like pressure (100–300 bar), temperature (60–140 ◦C), residence time (0.5–3 hours), and base, acidic, and neutral pH values. In order optimize the process parameters, Response Surface Methodology (RSM) has been used. Results show that removal efficiency of PAHs is between 82%-100%, where the highest PAHs removal efficiency (100%) has been observed in Test No. 22, with a pressure of 300 bars, temperature of 500°C, acidic pH equal to 5, and duration of 3 hours. In addition, the lowest removal efficiency of these compounds (82%) has been obtained in Test No. 26, with a pressure of 300 bars, temperature of 350°C, base pH of 9, and duration of half an hour. According to the results from this study, it has become clear that residence time is the most important and most effective parameter for removing PAHs from contaminated soil. Afterwards, temperature and pH are most influential with pressure showing the least effect. Using supercritical water method in appropriate conditions can eliminate more than 99% of aromatic contamination.
显示更多 [+] 显示较少 [-]Microbeads in Sediment, Dreissenid Mussels, and Anurans in the Littoral Zone of the Upper St. Lawrence River, New York. 全文
2019
Schessl, M. | Johns, C. | Ashpole, S. L.
Global plastic production has exceeded 300 million tons per year (Plastics Europe, 2015). In the marine and freshwater environments, larger plastics abrade and photo-degrade resulting in persistent environmental microplastics that are not effectively removed by existing wastewater treatment plants (WWTPs). The ecological effects of microplastics on the marine environment are poorly understood, with even less attention to freshwater systems. To assess whether microplastics have infiltrated food webs of shallow nearshore ecosystems of the St. Lawrence River, we sampled four sites along the international section of the St. Lawrence River, from Alexandria Bay to Waddington, NY. Twelve sediment samples along with one hundred and forty-nine Dreissenid mussels (Dreissena polymorpha and D. bugensis) were collected from the littoral zone, and forty one road-killed anuran amphibian specimens were collected adjacent to the river. Sediment subsamples at two of four sediment sampling sites contained plastic micro-particles. No microbeads were detected within any of the Dreissenid mussels or anuran digestive tract samples. The Dreissenids were likely too small to ingest microbeads greater than 35 microns. Microplastics congregating in the littoral zone may pose a threat within the food web through potential ingestion, requiring further methodological development.
显示更多 [+] 显示较少 [-]Three-dimensional analytical models for time-dependent coefficients through uniform and varying plane input source in semi-infinite adsorbing porous media. 全文
2019
Yadav, R. R. | Yadav, V.
In the present study, analytical solutions are developed for three-dimensional advection-dispersion equation (ADE) in semi-infinite adsorbing saturated homogeneous porous medium with time dependent dispersion coefficient. It means porosity of the medium is filled with single fluid(water). Dispersion coefficient is considered proportional to seepage velocity while adsorption coefficient inversely proportional to dispersion coefficient. Solutions are derived for both uniform and varying plane input source. The source geometry, including shape and orientation, broadly act major role for the concentration profile through the entire transport procedure. Initially the porous domain is not solute free. It means domain is throughout uniformly polluted. With help of certain transformation advection-dispersion equation is reduced into constant coefficient. The governing advection-dispersion equation, initial and boundary condition is solved by applying Laplace Transform Technique (LTT). The desired closed-form solution for the line source in two-dimensions and point source in one-dimension of uniform and varying nature are also evaluated as particular cases. Effects of parameters and value on the solute transport are demonstrated graphically.
显示更多 [+] 显示较少 [-]