Challenges on the recycling of cigarette butts

Environmental Science and Pollution Research - Cigarette butt (CB) is a crucial litter in urban communities because it may contain various toxicants. Due to serious limitations on...     

Environmental assessment of RAMseS multipurpose electric vehicle compared to a conventional combustion engine vehicle

The RAMseS project, financed by the European Commission under the 6th framework Program, has the purpose of developing a solar powered agricultural vehicle in order to replace the conventional vehicles based on internal combustion engines (ICE). In the present study, we report a comparison of life-cycle emission between two systems; a conventional ICE vehicle (ICEV) and the RAMseS electrical vehicle (EV). The study has been conducted by designing a specific model and using the SimaPro software. The results show that the RAMseS system is considerably more environmentally friendly than conventional ICE based system and that, specifically, it can avoid the emission of about 23 ton of CO_2equ per year. Regarding all other pollutants, we found that the RAMseS system is 2.6 times more efficient than the ICEV. The main contribution to emissions of the RAMseS system is due to the batteries which contribute for a 73% of the total. Therefore, further improvement can be obtained with the use of more advanced battery systems, not based on lead.     

Soil reinforcement with recycled carpet wastes.

A root or fibre-reinforced soil behaves as a composite material in which fibres of relatively high tensile strength are embedded in a matrix of relatively plastic soil. Shear stresses in the soil mobilize tensile resistance in the fibres, which in turn impart greater strength to the soil. A research project has been undertaken to study the influence of synthetic fibrous materials for improving the strength characteristics of a fine sandy soil. One of the main objectives of the project is to explore the conversion of fibrous carpet waste into a value-added product for soil reinforcement. Drained triaxial tests were conducted on specimens, which were prepared in a cylindrical mould and compacted at their optimum water contents. The main test variables included the aspect ratio and the weight percentage of the fibrous strips. The results clearly show that fibrous inclusions derived from carpet wastes improve the shear strength of silty sands. A model developed to simulate the effect of the fibrous inclusions accurately predicts the influence of strip content, aspect ratio and confining pressure on the shear strength of reinforced sand.     

CO<Subscript>2</Subscript> emission and economic growth of Iran

This research investigates the relationship between CO₂ emission and economic growth of Iran over 14 years from 1994 to 2007 using a national panel data set. The statistical and emission intensity methodologies are used for analyzing the data series. The study finds evidence supporting parameters which conclude the stability of significant correlation between CO₂ emission and economic development over time during the years under investigation in Iran. This relationship is investigated and discussed for the energy sectors of the country as well. The results confirm that in all sectors except of agricultural, there is a positive strong correlation between CO₂ emission and economic growth throughout the study period. In most sectors, CO₂ emission intensity (the emission per unit of GDP) doesn’t show increasing trends while the absolute emission is rapidly increasing by the economic growth.     

Sequentially coupled flow-geomechanical modeling of underground coal gasification for a three-dimensional problem

Underground coal gasification (UCG) has been identified as an environmentally friendly technique for gasification of deep un-mineable coal seams in situ. This technology has the potential to be a clean and promising energy provider from coal seams with minimal greenhouse gas emission. The UCG eliminates the presence of coal miners underground hence, it is believed to be a much safer technique compared to the deep coal mining method. The UCG includes drilling injection and production wells into the coal seam, igniting coal, and injecting oxygen-based mix to facilitate coal gasification. Produced syngas is extracted from the production well. Evolution of a cavity created from the gasification process along with high temperature as well as change in pore fluid pressure causes mechanical changes to the coal and surrounding formations. Therefore, simulation of the gasification process alone is not sufficient to represent this complex thermal-hydro-chemical–mechanical process. Instead, a coupled flow and geomechanical modeling can help better represent the process by allowing simultaneous observation of the syngas production, advancement of the gasification chamber, and the cavity growth. Adaptation of such a coupled simulation would aid in optimization of the UCG process while helping controlling and mitigating the environmental risks caused by geomechanical failure and syngas loss to the groundwater. This paper presents results of a sequentially coupled flow-geomechanical simulation of a three-dimensional (3D) UCG example using the numerical methodology devised in this study. The 3D model includes caprock on top, coal seam in the middle, and another layer of rock underneath. Gasification modeling was conducted in the Computer Modelling Group Ltd. (CMG)’s Steam, Thermal, and Advanced processes Reservoir Simulator (STARS). Temperature and fluid pressure of each grid block as well as the cavity geometry, at the timestep level, were passed from the STARS to the geomechanical simulator i.e. the Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) computer program (from the Itasca Consulting Group Inc.). Key features of the UCG process which were investigated herein include syngas flow rate, cavity growth, temperature and pressure profiles, porosity and permeability changes, and stress and deformation in coal and rock layers. It was observed that the coal matrix deformed towards the cavity, displacement and additional stress happened, and some blocks in the coal and rock layers mechanically failed.     

Turbulent velocity profile in fully-developed open channel flows

The determination of velocity profile in turbulent narrow open channels is a difficult task due to the significant effects of the anisotropic turbulence that involve the Prandtl’s second type of secondary flow occurring in the cross section. With these currents the maximum velocity appears below the free surface that is called dip phenomenon. The well-known logarithmic law describes the velocity distribution in the inner region of the turbulent boundary layer but it is not adapted to define the velocity profile in the outer region of narrow channels. This paper relies on an analysis of the Navier–Stokes equations and yields a new formulation of the vertical velocity profile in the center region of steady, fully developed turbulent flows in open channels. This formulation is able to predict time averaged primary velocity in the outer region of the turbulent boundary layer for both narrow and wide open channels. The proposed law is based on the knowledge of the aspect ratio and involves a parameter C_Ar depending on the position of the maximum velocity (ξ_dip). ξ_dip may be derived, either from measurements or from an empirical equation given in this paper. A wide range of longitudinal velocity profile data for narrow open channels has been used for validating the model. The agreement between the measured and the computed velocities is rather good, despite the simplification used.     

Bioremediation of toxic metals mercury and cesium using three types of biosorbent: bacterial exopolymer,gall nut,and oak fruit particles

Cesium and mercury are two mono-valent elements which can be found in toxic industrial, medical, and nuclear wastes. Their presence in the environment has deleterious effects on the ecosystem, living organisms including humans. Due to the chemical nature of these metals, bioremediation by conventional methods is more difficult to achieve compared to other metals. In this study, we used three biosorbents (oak powder, gall nut, and bacterial exopolymer) for the bioremediation of Hg and Cs. Bio-polymer was produced in the GMS mineral broth. Synthetic wastes of Hg(NO₃)₂ and isotope Cs-133 as the single-metal solutions were used. The biorefining process was carried out in glass columns, made of Pyrex, with dimensions 20?×?7/2?cm² with a V-shaped bottom. The samples were analyzed using atomic absorption. The experimental results showed that eliminated metal percent by oak powder, gall nut, and bacterial exopolymer were, respectively, of 94.8%, 96%, and 13.8% for Hg and 7.8%, 4.4%, and 69.4% for Cs. The tests revealed that Ca⁺⁺, when used as flocculant, played a key role in both biosorption and bio-precipitation rates. Consequently, it was concluded that the investigated biosorbents could be use as an integrated biosorption system for the refinement of mixed wastes.     

Synthesis and antibacterial activity of a Fe3O4–AgCl nanocomposite against Escherichia coli

In this investigation, Fe₃O₄ magnetic nanoparticles (MNPs) were prepared by the alkalinization of an aqueous medium containing ferrous sulfate and ferric chloride. In the next step, a Fe₃O₄–AgCl magnetic nanocomposite was fabricated by the drop-by-drop addition of silver nitrate solution into a NaCl solution containing Fe₃O₄ MNPs. All prepared nanoparticles were characterized by transition electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). Both particle types varied in size from 2.5 to 20?nm, with an average size of 7.5?nm for Fe₃O₄ MNPs and 12.5?nm for Fe₃O₄–AgCl nanocomposites. The antibacterial effect of the Fe₃O₄ MNPs and fabricated Fe₃O₄–AgCl nanocomposites against Escherichia coli (ATCC 35218) were investigated by conventional serial agar dilution method using the Müller–Hinton Agar medium. The minimum inhibitory concentration was 4?mg?mL^?1 for Fe₃O₄ MNPs and 2?mg?mL^?1 for the Fe₃O₄–AgCl magnetic nanocomposites. Time-kill course assays showed that the Fe₃O₄–AgCl magnetic nanocomposites successfully killed all inoculated bacterial cells during an exposure time of 60?min. The antibacterial activity of recycled Fe₃O₄–AgCl magnetic nanocomposites over four 60?min cycles of antibacterial treatment was further tested against E. coli by the colony-forming unit (CFU) method. The antibacterial efficiency of the nanocomposites was constant over two cycles of antibacterial testing.