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Michael D Annable - One of the best experts on this subject based on the ideXlab platform.
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effect of increased groundwater viscosity on the remedial performance of surfactant enhanced air sparging
Journal of Contaminant Hydrology, 2018Co-Authors: Jaekyeong Choi, Hobin Kwon, Michael D AnnableAbstract:Abstract The effect of groundwater viscosity control on the performance of surfactant-enhanced air sparging (SEAS) was investigated using 1- and 2-dimensional (1-D and 2-D) bench-scale physical models. The viscosity of groundwater was controlled by a thickener, sodium carboxymethylcellulose (SCMC), while an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), was used to control the surface tension of groundwater. When resident DI water was displaced with a SCMC solution (500 mg/L), a SDBS solution (200 mg/L), and a solution with both SCMC (500 mg/L) and SDBS (200 mg/L), the air saturation for sand-packed columns achieved by air sparging increased by 9.5%, 128%, and 154%, respectively, (compared to that of the DI water-saturated column). When the resident water contained SCMC, the minimum air pressure necessary for air sparging processes increased, which is considered to be responsible for the increased air saturation. The extent of the sparging Influence Zone achieved during the air sparging process using the 2-D model was also affected by viscosity control. Larger sparging Influence Zones (de-saturated Zone due to air injection) were observed for the air sparging processes using the 2-D model initially saturated with high-viscosity solutions, than those without a thickener in the aqueous solution. The enhanced air saturations using SCMC for the 1-D air sparging experiment improved the degradative performance of gaseous oxidation agent (oZone) during air sparging, as measured by the disappearance of fluorescence (fluorescein sodium salt). Based on the experimental evidence generated in this study, the addition of a thickener in the aqueous solution prior to air sparging increased the degree of air saturation and the sparging Influence Zone, and enhanced the remedial potential of SEAS for contaminated aquifers.
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changes in air flow patterns using surfactants and thickeners during air sparging bench scale experiments
Journal of Contaminant Hydrology, 2015Co-Authors: Michael D AnnableAbstract:Abstract Air injected into an aquifer during air sparging normally flows upward according to the pressure gradients and buoyancy, and the direction of air flow depends on the natural hydrogeologic setting. In this study, a new method for controlling air flow paths in the saturated Zone during air sparging processes is presented. Two hydrodynamic parameters, viscosity and surface tension of the aqueous phase in the aquifer, were altered using appropriate water-soluble reagents distributed before initiating air sparging. Increased viscosity retarded the travel velocity of the air front during air sparging by modifying the viscosity ratio. Using a one-dimensional column packed with water-saturated sand, the velocity of air intrusion into the saturated region under a constant pressure gradient was inversely proportional to the viscosity of the aqueous solution. The air flow direction, and thus the air flux distribution was measured using gaseous flux meters placed at the sand surface during air sparging experiments using both two-, and three-dimensional physical models. Air flow was found to be Influenced by the presence of an aqueous patch of high viscosity or suppressed surface tension in the aquifer. Air flow was selective through the low-surface tension (46.5 dyn/cm) region, whereas an aqueous patch of high viscosity (2.77 cP) was as an effective air flow barrier. Formation of a low-surface tension region in the target contaminated Zone in the aquifer, before the air sparging process is inaugurated, may induce air flow through the target Zone maximizing the contaminant removal efficiency of the injected air. In contrast, a region with high viscosity in the air sparging Influence Zone may minimize air flow through the region prohibiting the region from de-saturating.
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effect of surface tension reduction on voc removal during surfactant enhanced air sparging
Journal of Environmental Science and Health Part A-toxic\ hazardous Substances & Environmental Engineering, 2006Co-Authors: Michael D AnnableAbstract:In this study, the effect of decreased surface tension of water on the removal efficiency of a volatile organic compound (VOC) during air sparing was evaluated using a laboratory-scale, two-dimensional physical model packed with sand and water containing dissolved toluene as a representative VOC. Two sets of air sparging experiments were performed: the first at a surface tension of 69 dyne/cm with no surfactant applied, and with a toluene concentration of 110 mg/L; the second at a surface tension of 50 dyne/cm due to 110 mg/L of anionic surfactant, and 99 mg/L of toluene. Under the experimental conditions used in this study, the sparging Influence Zone estimated at the lower surface tension was about 2.5 times that estimated at the high surface tension. Also the rate of toluene removal by air sparging was found to be much faster at the lower surface tension. The sparging time required for 50% removal of the initial mass of toluene was 16.8 hours at 50 dyne/cm, which was much smaller than 82.5 hours measur...
Andrzej Dziedzic - One of the best experts on this subject based on the ideXlab platform.
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the Influence of tempering on the microstructure and microhardeness of hs 6 5 2 steel in the area of overlapping remelting obtained with the use of the gtaw method
2010Co-Authors: Andrzej DziedzicAbstract:There have been results of the metallographic research and the measurements of the microhardness of the surface layer of the high speed steel HS 6-5-2 presented from the areas of overlapping remelting. Remelting of the surface layer of the steel was made with the electric arc. After the remelting, there was the conventional tempering done 2x2 hours in the temperature of 560 0 C. There is a result from the research that in the area of overlapping of the heat Influence Zone of the second remelting (HIZ2) on the first remelting Zone (R1) there is a decrease of the microhardness. Conducting the conventional tempering causes the increase of microhardness, but it does not change the shape of the microhardness curve. The material included in the paper is the attempt of the answer for the question, in which attempt and why is there a decrease of microhardness of the surface layer of the steel, mentioned above.
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microhardness changes of surface layer of hs 6 5 2 steel in the areas overlapping remelting obtained with the use of gtaw method
Archives of Foundry Engineering, 2008Co-Authors: A Bylica, Andrzej DziedzicAbstract:The work presents test results of microhardness of surface layer of HS 6-5-2 high-speed steel from areas overlapping remelting. The surface layer of the steel was remelted using the GTAW method. The microhardness was measured using the Vickers method. The work shows that the area, where the heat Influence Zone of the second remelting overlapping on the first remelting Zone is characterizes by the microhardness lower about approx. 200 HV0,065.
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the microstructure of hs 6 5 2 steel in the areas overlapping remelting obtained by the use of gtaw method
Archives of Foundry Engineering, 2008Co-Authors: Andrzej DziedzicAbstract:The work presents microstructures of HS 6-5-2 high-speed steel from the areas overlapping remelting. The surface layer of the steel was remelted using the GTAW method. The microstructure photos were taken with LM and SEM microscopes. On microstructure photos there are visible results of heat effect overlapping remelting. The conclusions of the work show that as a result of crystallization in the Zone of first remelting a system of crystals is formed which is forced the direction of heat removal from the front of the crystallization through the solid phase. With overlapping the second remelting on the first one, as a result of retreating crystallization on the border of the second and the first remelting the direction of crystals packing changes. Additionally, the heat Influence Zone of the second remelting changes the structure of the first remelting significantly. Aforementioned factors determine the decrease of the microhardness value of the surface layer within the areas overlapping remelting.
Shtavdaker Maria - One of the best experts on this subject based on the ideXlab platform.
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Environmental safety assessment in the Influence Zone of the existing Zelenchukskaya HPP-PSHS and Krasnogorsk HPP-1, HPP-2 under construction in the area of Ust-Dzhegutinsky reservoir location
'EDP Sciences', 2021Co-Authors: Bondarenko Vladimir, Ylyasov Alla-brerdi, Mirzoev M., Shtavdaker MariaAbstract:«Environmental safety “in the considered spatial limits of the Upper Kuban basin geosystem (F w=11,0*103 km3, W l=3,3*103 km3, Watm=110*103 Wb.g.U.K..=124,3*103 km3) makes up about 21.4% of the spatial limits of the Kuban River, where water resources are formed according to the average long-term data about 3,0 km3, which are used in various sectors of economic activity, including for the electricity generation at Zelenchukskaya HPP-PSHS and Krasnogorsk HPP-1 and HPP-2 under construction with installed power up to 25 mW, located below the HPP-PSHS Zelenchukskaya section and above the alignment (12 km) of the Ust-Dzhegutinsky reservoir. Such HPP-PSHS placement on a 15 km long section of the Kuban Zelenchukskaya riverbed and Krasnogorsk HPP-1 and HPP-2 under construction determined a highly active Zone of Influence (IV), which is caused by a change in the natural hydrograph of the Kuban River, with the formation of the channel flow movement unsteady hydraulic regime in the considered section of the river to the Ust-Dzhegutinsky reservoir. Unsteady changes in the water level in the Ust-Dzhegutinsky reservoir affects the pressure front structures safety, the functional operation of the water intake system in the Bolshoi Stavropol Canal (BSC) and hydraulic BSC operation. To assess the level of “environmental safety”, it became necessary to develop a mathematical model of the impact of the HPP-PSHS functional work and Krasnogorsk HPP-1 and HPP-2 under construction at the level modes of operation of the Ust-Dzhegutinsky reservoir
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Assessment of environmental safety in the Influence Zone of the current Zelenchukskaya HPP-PSPP and Krasnogorsky HPP-1, HPP-2 under construction in the area of Ust-Dzhegutinsky reservoir location
'EDP Sciences', 2021Co-Authors: Bondarenko Vladimir, Ylyasov Alla-brerdi, Semenova Elena, Mirzoev Marat, Shtavdaker MariaAbstract:“Environmental safety” in the considered spatial limits of the basin geosystem of Upper Kuban (Fw = 11.0 * 103 km3, W lit.=3.3*103 km3, Watm.=110 * 103 W BGUK =124.3*103 km3) is about 21.4% of the spatial limits of the Kuban River, where water resources are formed according to the average long-term data of about 3.0 km3, which are used in various sectors of economic activity, including the generation of electric energy at the Zelenchukskaya HPP-PSPP and the Krasnogorsk HPP-1 and HPP-2 under construction with an installed capacity of up to 25 MW, located below the Zelenchukskaya HPP-PSPP target and above the target (12 km) Ust-Dzhegutinsky reservoir. Such placement of the Zelenchukskaya HPP-PSPP and the Krasnogorsk HPP-1 and HPP-2 under construction on a 15 km long section of the Kuban Riverbed has determined a highly active Zone of Influence (IV), which is caused by a change in the natural hydrograph of the Kuban River, with the formation of an unstated hydraulic regime of the channel flow movement on the considered section of the river to the Ust-Dzhegutinsky reservoir. The relentless changes in the water level in the Ust-Dzhegutinsky reservoir affect the pressure safety front structures, the functional operation of the water intake hydroelectric complex in the Bolshoy Stavropol Canal (BSC) and the hydraulic operation of the BSC. To assess the “environmental safety” level, it became necessary to develop a mathematical model of the functional operation Influence of the Zelenchukskaya HPP-PSPP and the Krasnogorsk HPP-1 and HPP-2 under construction on the Ust-Dzhegutinsky reservoir operation level modes
Charles Wang Wai Ng - One of the best experts on this subject based on the ideXlab platform.
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three dimensional deformation behaviour of a multi propped excavation at a greenfield site at shanghai soft clay
Tunnelling and Underground Space Technology, 2015Co-Authors: Yi Hong, Charles Wang Wai NgAbstract:Abstract Despite the large number of excavation-induced ground deformations reported in the literature, it is still not easy to differentiate ground deformations due to excavation in congested sites (where the ground is strengthened by underground structures) from those due to excavation in “greenfield” sites. To investigate and compare excavation-induced ground deformations in “greenfield” sites and congested sites, in this study a multi-propped excavation at a “greenfield” site in Shanghai soft clay was heavily instrumented and the measured ground deformations were compared with those reported from six excavations conducted under similar conditions but in congested sites in Shanghai. Field measurements from the “greenfield” site show that near the centre of the excavation, the maximum ground settlement (δv-max) ranged from 0.22% to 0.27% of the final excavation depth (He), with a major Influence Zone extending to 3He behind the wall. The six excavations (near the main station) at congested sites in Shanghai had δv-max values ranging from 0.01% to 0.1% He (with a mean of about 0.05% He) and so were about 20% of that at the “greenfield” site. In addition, the major Influence Zone of ground settlement at the “greenfield” site extended 33% further than those at the congested sites. On the other hand, the measured maximum lateral wall displacement δh-max (0.24–0.37% He) at the “greenfield” site was comparable to those (0.13–0.43% He) at the congested sites. Due to the corner effect (soil arching around corners) at the “greenfield” site, the average δh-max and δv-max near the corners of the site were 45% and 36% smaller than those near the centre. The maximum tilt of ground perpendicular to the excavation was 1/1064, which was similar to that parallel to the excavation (1/1050).
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Experimental investigation of induced suction distribution in a grass-covered soil
Ecological Engineering, 2013Co-Authors: Charles Wang Wai Ng, K.x. Woon, Anthony Kwan LeungAbstract:Abstract Evapotranspiration from a grass-covered ground is known to induce suction by soil evaporation and grass transpiration. However, grass-induced suction in the ground when it is subjected to wetting and drying are not yet well understood. In this study, a laboratory test program was conducted to investigate the magnitude and distribution of suction induced by Bermuda grass growing in silty sand. In total, four test boxes compacted with silty sand were prepared, three of which covered with Bermuda grass while one test box was left bare as control. All the four test boxes were subjected to wetting and drying in a plant room with temperature and humidity controlled. Under identical atmospheric conditions and initial soil density and water content, peak suction induced within the root Zone in grassed soil was 1.5 times higher than that in bare soil after 20 days of drying. A vertical suction Influence Zone was identified to be up to four times the root depth while the lateral suction Influence Zone was one diameter of ring collar away from the centre of the plot. Upon wetting, suction retained at depth right below the root Zone in grassed soil was found to be 40% higher than that in bare soil. For three grass replicates that were germinated under identical atmospheric conditions, they produced different shoot lengths and induced different magnitudes of suction. No direct correlation between grass shoot length and grass-induced suction could be found.
Bondarenko Vladimir - One of the best experts on this subject based on the ideXlab platform.
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Environmental safety assessment in the Influence Zone of the existing Zelenchukskaya HPP-PSHS and Krasnogorsk HPP-1, HPP-2 under construction in the area of Ust-Dzhegutinsky reservoir location
'EDP Sciences', 2021Co-Authors: Bondarenko Vladimir, Ylyasov Alla-brerdi, Mirzoev M., Shtavdaker MariaAbstract:«Environmental safety “in the considered spatial limits of the Upper Kuban basin geosystem (F w=11,0*103 km3, W l=3,3*103 km3, Watm=110*103 Wb.g.U.K..=124,3*103 km3) makes up about 21.4% of the spatial limits of the Kuban River, where water resources are formed according to the average long-term data about 3,0 km3, which are used in various sectors of economic activity, including for the electricity generation at Zelenchukskaya HPP-PSHS and Krasnogorsk HPP-1 and HPP-2 under construction with installed power up to 25 mW, located below the HPP-PSHS Zelenchukskaya section and above the alignment (12 km) of the Ust-Dzhegutinsky reservoir. Such HPP-PSHS placement on a 15 km long section of the Kuban Zelenchukskaya riverbed and Krasnogorsk HPP-1 and HPP-2 under construction determined a highly active Zone of Influence (IV), which is caused by a change in the natural hydrograph of the Kuban River, with the formation of the channel flow movement unsteady hydraulic regime in the considered section of the river to the Ust-Dzhegutinsky reservoir. Unsteady changes in the water level in the Ust-Dzhegutinsky reservoir affects the pressure front structures safety, the functional operation of the water intake system in the Bolshoi Stavropol Canal (BSC) and hydraulic BSC operation. To assess the level of “environmental safety”, it became necessary to develop a mathematical model of the impact of the HPP-PSHS functional work and Krasnogorsk HPP-1 and HPP-2 under construction at the level modes of operation of the Ust-Dzhegutinsky reservoir
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Assessment of environmental safety in the Influence Zone of the current Zelenchukskaya HPP-PSPP and Krasnogorsky HPP-1, HPP-2 under construction in the area of Ust-Dzhegutinsky reservoir location
'EDP Sciences', 2021Co-Authors: Bondarenko Vladimir, Ylyasov Alla-brerdi, Semenova Elena, Mirzoev Marat, Shtavdaker MariaAbstract:“Environmental safety” in the considered spatial limits of the basin geosystem of Upper Kuban (Fw = 11.0 * 103 km3, W lit.=3.3*103 km3, Watm.=110 * 103 W BGUK =124.3*103 km3) is about 21.4% of the spatial limits of the Kuban River, where water resources are formed according to the average long-term data of about 3.0 km3, which are used in various sectors of economic activity, including the generation of electric energy at the Zelenchukskaya HPP-PSPP and the Krasnogorsk HPP-1 and HPP-2 under construction with an installed capacity of up to 25 MW, located below the Zelenchukskaya HPP-PSPP target and above the target (12 km) Ust-Dzhegutinsky reservoir. Such placement of the Zelenchukskaya HPP-PSPP and the Krasnogorsk HPP-1 and HPP-2 under construction on a 15 km long section of the Kuban Riverbed has determined a highly active Zone of Influence (IV), which is caused by a change in the natural hydrograph of the Kuban River, with the formation of an unstated hydraulic regime of the channel flow movement on the considered section of the river to the Ust-Dzhegutinsky reservoir. The relentless changes in the water level in the Ust-Dzhegutinsky reservoir affect the pressure safety front structures, the functional operation of the water intake hydroelectric complex in the Bolshoy Stavropol Canal (BSC) and the hydraulic operation of the BSC. To assess the “environmental safety” level, it became necessary to develop a mathematical model of the functional operation Influence of the Zelenchukskaya HPP-PSPP and the Krasnogorsk HPP-1 and HPP-2 under construction on the Ust-Dzhegutinsky reservoir operation level modes