In this paper, the discussion is concentrated on the properties of the polluted sediments and the combination of clean-up and disposal process for the upper layer heavily polluted sediments with good flowability. Base...In this paper, the discussion is concentrated on the properties of the polluted sediments and the combination of clean-up and disposal process for the upper layer heavily polluted sediments with good flowability. Based on the systematic analyses of various clean-up processes, a suitable engineering process has been evaluated and recommended. The process has been applied to the river reclamation in Yangpu District of Shanghai City, China. An improved centrifuge is used for dewatering the dredged sludge, which plays an important role in the combination of clean-up and disposal process. The assessment of the engineering process shows its environmental and technical economy feasibility, which is much better than that of traditional dredging-disposal processes.展开更多
Advanced integrated gasification combined cycle （IGCC） power generation systems require the development of high-temperature, regenerable desulfurization sorbents, which are capable of removing hydrogen sulfide from ...Advanced integrated gasification combined cycle （IGCC） power generation systems require the development of high-temperature, regenerable desulfurization sorbents, which are capable of removing hydrogen sulfide from coal gasifier gas to very low levels. In this paper, zinc ferrites prepared by co-precipitation were identified as a novel coal gas desulfurization sorbent at high temperature. Preparation of zinc ferrite and effects of binders on pore volume, strength and desulfurization efficiency of zinc ferrite desulfurizer were studied. Moreover, the behavior of zinc ferrite sorbent during desulfurization and regeneration under the temperature range of 350-400 ℃ are investigated. Effects of binders on the pore volume, mechanical strength and desulfurization efficiency of zinc ferrite sorbents indicated that the addition of kaolinite to zinc ferrite desulfurizer seems to be superior to other binders under the experimental conditions.展开更多
A rapid, cost effective and reliable analytical method was developed and validated for the simultaneous determination of four estrogens (17 β-estradiol, 17 α-ethinylestradiol, estrone, and estriol) in compost sample...A rapid, cost effective and reliable analytical method was developed and validated for the simultaneous determination of four estrogens (17 β-estradiol, 17 α-ethinylestradiol, estrone, and estriol) in compost samples from the biodegradation of biological infectious hazardous wastes. Ultrasonic solvent extraction, using methanol as extraction solvent, coupled with SPE clean-up, using cartridges HLB 60 mg - 6 ml Supelco®<sup></sup> and acetonitrile for reconstitution of eluents, was used for the simultaneous extraction of the four estrogens. Mean recoveries in the range of 98% - 107% were obtained. All compounds were separated in a single gradient run by UHPLC Kinetex<sup>TM</sup> 2.6 μm XB-C18 100 ÅLC (50 × 4.6 mm) column. Analytes were detected via multiple reaction monitoring (MRM) using an AB SCIEX API-5000TM triple quadrupole (Applied Biosystems/MDS SCIEX) with electrospray ionization in negative mode. Isocratic mobile phase of Water:ACN (50:50) resulted to be the optimum. Limits of detection and quantification were on the order of 0.66 ng·g<sup>-1</sup> and 2 ng·g<sup>-1</sup> for all the estrogens. These limits were lower than most of the values reported in the literature for similar matrices. Suitable level of linearity, good repeatability and reproducibility with coefficients of variation is lower than 11.7%, 6.8% and 8.3%, respectively.展开更多
Based on differential game theory,the decision-making problem of two homogeneous countries facing transboundary marine litter governance is studied.On the basis of assuming that the input of marine litter is an exogen...Based on differential game theory,the decision-making problem of two homogeneous countries facing transboundary marine litter governance is studied.On the basis of assuming that the input of marine litter is an exogenous variable,the focus is on reducing the accumulation of marine litter through cleanup and transfer processing by both parties.Considering the constant and increasing input of marine litter,in the framework of international agreement constraints,the analysis of the game behavior of the players in the marine litter governance under the open-loop strategy(in the case of agreement constraints)and the Markov strategy(in the case of no agreement constraints)was compared and analyzed.The research results show that when the direct pollution cost of marine litter is high enough,both sides of the game adopt an open-loop strategy that complies with the constraints of the agreement,which can reduce the accumulation of marine litter and improve the environmental quality.However,when there is a high initial accumulation of marine litter,the Markov strategy without protocol constraints will be better than the open-loop strategy.In the case that marine litter does not need to be transferred,there will be no difference between the two sides of the game adopting the Markov strategy and adopting the open-loop strategy on the equilibrium growth path.展开更多
Elevated-temperature pressure swing adsorption is a promising technique for producing high purity hydrogen and controlling greenhouse gas emissions. Thermodynamic analysis indicated that the CO in H-rich gas could be ...Elevated-temperature pressure swing adsorption is a promising technique for producing high purity hydrogen and controlling greenhouse gas emissions. Thermodynamic analysis indicated that the CO in H-rich gas could be controlled to trace levels of below 10 ppm by in situ reduction of the COconcentration to less than 100 ppm via the aforementioned process. The COadsorption capacity of potassiumpromoted hydrotalcite at elevated temperatures under different adsorption（mole fraction, working pressure） and desorption（flow rate, desorption time, steam effects） conditions was systematically investigated using a fixed bed reactor. It was found that the COresidual concentration before the breakthrough of COmainly depended on the total amount of purge gas and the COmole fraction in the inlet syngas.The residual COconcentration and uptake achieved for the inlet gas comprising CO（9.7 mL/min） and He（277.6 mL/min） at a working pressure of 3 MPa after 1 h of Ar purging at 300 mL/min were 12.3 ppm and0.341 mmol/g, respectively. Steam purge could greatly improve the cyclic adsorption working capacity, but had no obvious benefit for the recovery of the residual COconcentration compared to purging with an inert gas. The residual COconcentration obtained with the adsorbent could be reduced to 3.2 ppm after 12 h of temperature swing at 450 °C. A new concept based on an adsorption/desorption process, comprising adsorption, steam rinse, depressurization, steam purge, pressurization, and high-temperature steam purge, was proposed for reducing the steam consumption during CO/COpurification.展开更多
In this paper, a new method of topological cleanup for quadrilateral mesh is presented. The method first selects a patch of mesh around an irregular node. It then seeks the best connection of the selected patch accord...In this paper, a new method of topological cleanup for quadrilateral mesh is presented. The method first selects a patch of mesh around an irregular node. It then seeks the best connection of the selected patch according to its irregular valence using a new topological operation： small polygon reconnection （SPR）. By replacing the original patch with an optimal one that has less irregular valence, mesh quality can be improved. Three applications based on the proposed approach are enumerated： （1） improving the quality of a quadrilateral mesh, （2） converting a triangular mesh to a quadrilateral one, and （3） adapting a triangle generator to a quadrilateral one. The presented method is highly effective in all three applications.展开更多
Medical wastes have been implicated in river pollution in developing countries and most often people depend on water from such rivers for sources of livelihood. Phthalates (endocrine disruptors) are major components i...Medical wastes have been implicated in river pollution in developing countries and most often people depend on water from such rivers for sources of livelihood. Phthalates (endocrine disruptors) are major components in medical wastes and are commonly found contaminants in aquatic environment. Most sewage treatment facilities handling medical waste are inefficient due to overuse and poor maintenance and discharge directly into rivers. This study aimed to investigate the identity and estimates the concentration of phthalates in supposed treated medical wastes from a hospital sewer and water from a receiving river. Samples were randomly collected before and after treatment by the sewer plants, while samples were randomly collected along the course of the river starting from point of discharge. Control samples were taken from upstream about 500 m along the river course. The samples were extracted by liquid-liquid chroma- tographic process using dichloromethane, after which they were cleaned up in a column of silica gel using hexane as the mobile solvent. The cleaned extracts were analyzed by HPLC. The concentrations (μg/L) of dimethyl-, diethyl-, diphenyl-, dibutyl- and di-(2-ethyl)hexyl phthalates ranged from 62.81 ± 18.53;4.74 ± 3.57;2.05 ± 1.80;11.40 ± 5.58 to 141.92 ± 35.8 respectively in the sewer waste. The receiving river had a concentration (μg/L) of 9.17 ± 14.02;0.18 ± 0.31;0.48 ± 0.84;2.84 ± 1.21;61.72 ± 38.35 respectively for dimethyl-, diethyl-, diphenyl-, dibutyl- and di-(2-ethyl) hexyl phthalates. These concentrations were higher than control and far exceeded the USEPA limits of 3 μg/l recom- mended for phthalates in water. Contaminants of aquatic environment by untreated wastes from hospitals has serious implications on public health and environment as human risks for phthalate esters downstream are high and this calls for urgent need to develop strategy to build incentives for compliance in treatment and discharge of wastes into river waters.展开更多
The study assesses the spatial distribution and sources of mercury contamination in the Ankobra River Basin in southwestern Ghana and discusses possible remediation options and challenges. Eighty-two (82) samples of w...The study assesses the spatial distribution and sources of mercury contamination in the Ankobra River Basin in southwestern Ghana and discusses possible remediation options and challenges. Eighty-two (82) samples of water and streambed sediments from areas of active and historic artisanal mining and historic mine spoil from large-scale mining were analysed for their total mercury content using cold vapour Atomic Fluorescence Spectrometry (CV-AAS). The highest Hg concentrations were recorded from historic mine tailings, legacy of large scale mines in the area, which averaged 795 ppb but ranged from 80 ppb to 2500 ppb. Concentrations in streambed sediments averaged 139 ppb, but ranged from 63 ppb to 270 ppb. Water, expectedly, gave the lowest Hg concentrations with a mean value of 1.5 ppb, but ranged from below detection to 8 ppb. Areas worked by artisanal miners and historic tailings dumps at Bondaye and Prestea recorded the highest mercury values. These high mercury concentration sites constitute potential sources of major mercury pollution in the area and therefore require major and urgent clean up to mitigate any major health risks. However, any remediation strategy would require further and detailed study of the contaminated sites and an evaluation of known remediation techniques to achieve maximum results.展开更多
文摘In this paper, the discussion is concentrated on the properties of the polluted sediments and the combination of clean-up and disposal process for the upper layer heavily polluted sediments with good flowability. Based on the systematic analyses of various clean-up processes, a suitable engineering process has been evaluated and recommended. The process has been applied to the river reclamation in Yangpu District of Shanghai City, China. An improved centrifuge is used for dewatering the dredged sludge, which plays an important role in the combination of clean-up and disposal process. The assessment of the engineering process shows its environmental and technical economy feasibility, which is much better than that of traditional dredging-disposal processes.
基金the Ministry of Science and Technology of China under the Grant No. G2005CB221203the Natural Science Foundation of China under Contract No. 20576087.
文摘Advanced integrated gasification combined cycle （IGCC） power generation systems require the development of high-temperature, regenerable desulfurization sorbents, which are capable of removing hydrogen sulfide from coal gasifier gas to very low levels. In this paper, zinc ferrites prepared by co-precipitation were identified as a novel coal gas desulfurization sorbent at high temperature. Preparation of zinc ferrite and effects of binders on pore volume, strength and desulfurization efficiency of zinc ferrite desulfurizer were studied. Moreover, the behavior of zinc ferrite sorbent during desulfurization and regeneration under the temperature range of 350-400 ℃ are investigated. Effects of binders on the pore volume, mechanical strength and desulfurization efficiency of zinc ferrite sorbents indicated that the addition of kaolinite to zinc ferrite desulfurizer seems to be superior to other binders under the experimental conditions.
文摘A rapid, cost effective and reliable analytical method was developed and validated for the simultaneous determination of four estrogens (17 β-estradiol, 17 α-ethinylestradiol, estrone, and estriol) in compost samples from the biodegradation of biological infectious hazardous wastes. Ultrasonic solvent extraction, using methanol as extraction solvent, coupled with SPE clean-up, using cartridges HLB 60 mg - 6 ml Supelco®<sup></sup> and acetonitrile for reconstitution of eluents, was used for the simultaneous extraction of the four estrogens. Mean recoveries in the range of 98% - 107% were obtained. All compounds were separated in a single gradient run by UHPLC Kinetex<sup>TM</sup> 2.6 μm XB-C18 100 ÅLC (50 × 4.6 mm) column. Analytes were detected via multiple reaction monitoring (MRM) using an AB SCIEX API-5000TM triple quadrupole (Applied Biosystems/MDS SCIEX) with electrospray ionization in negative mode. Isocratic mobile phase of Water:ACN (50:50) resulted to be the optimum. Limits of detection and quantification were on the order of 0.66 ng·g<sup>-1</sup> and 2 ng·g<sup>-1</sup> for all the estrogens. These limits were lower than most of the values reported in the literature for similar matrices. Suitable level of linearity, good repeatability and reproducibility with coefficients of variation is lower than 11.7%, 6.8% and 8.3%, respectively.
基金supported by the Qihang Project of Zhejiang University(Grant No.202016)。
文摘Based on differential game theory,the decision-making problem of two homogeneous countries facing transboundary marine litter governance is studied.On the basis of assuming that the input of marine litter is an exogenous variable,the focus is on reducing the accumulation of marine litter through cleanup and transfer processing by both parties.Considering the constant and increasing input of marine litter,in the framework of international agreement constraints,the analysis of the game behavior of the players in the marine litter governance under the open-loop strategy(in the case of agreement constraints)and the Markov strategy(in the case of no agreement constraints)was compared and analyzed.The research results show that when the direct pollution cost of marine litter is high enough,both sides of the game adopt an open-loop strategy that complies with the constraints of the agreement,which can reduce the accumulation of marine litter and improve the environmental quality.However,when there is a high initial accumulation of marine litter,the Markov strategy without protocol constraints will be better than the open-loop strategy.In the case that marine litter does not need to be transferred,there will be no difference between the two sides of the game adopting the Markov strategy and adopting the open-loop strategy on the equilibrium growth path.
基金financed by Shanxi Province Science and Technology Major Projects of MH2015-06
文摘Elevated-temperature pressure swing adsorption is a promising technique for producing high purity hydrogen and controlling greenhouse gas emissions. Thermodynamic analysis indicated that the CO in H-rich gas could be controlled to trace levels of below 10 ppm by in situ reduction of the COconcentration to less than 100 ppm via the aforementioned process. The COadsorption capacity of potassiumpromoted hydrotalcite at elevated temperatures under different adsorption（mole fraction, working pressure） and desorption（flow rate, desorption time, steam effects） conditions was systematically investigated using a fixed bed reactor. It was found that the COresidual concentration before the breakthrough of COmainly depended on the total amount of purge gas and the COmole fraction in the inlet syngas.The residual COconcentration and uptake achieved for the inlet gas comprising CO（9.7 mL/min） and He（277.6 mL/min） at a working pressure of 3 MPa after 1 h of Ar purging at 300 mL/min were 12.3 ppm and0.341 mmol/g, respectively. Steam purge could greatly improve the cyclic adsorption working capacity, but had no obvious benefit for the recovery of the residual COconcentration compared to purging with an inert gas. The residual COconcentration obtained with the adsorbent could be reduced to 3.2 ppm after 12 h of temperature swing at 450 °C. A new concept based on an adsorption/desorption process, comprising adsorption, steam rinse, depressurization, steam purge, pressurization, and high-temperature steam purge, was proposed for reducing the steam consumption during CO/COpurification.
基金supported by the National Natural Science Foundation of China (10972006, 11172004)National Basic Research Program of China (2010CB832701)
文摘In this paper, a new method of topological cleanup for quadrilateral mesh is presented. The method first selects a patch of mesh around an irregular node. It then seeks the best connection of the selected patch according to its irregular valence using a new topological operation： small polygon reconnection （SPR）. By replacing the original patch with an optimal one that has less irregular valence, mesh quality can be improved. Three applications based on the proposed approach are enumerated： （1） improving the quality of a quadrilateral mesh, （2） converting a triangular mesh to a quadrilateral one, and （3） adapting a triangle generator to a quadrilateral one. The presented method is highly effective in all three applications.
文摘Medical wastes have been implicated in river pollution in developing countries and most often people depend on water from such rivers for sources of livelihood. Phthalates (endocrine disruptors) are major components in medical wastes and are commonly found contaminants in aquatic environment. Most sewage treatment facilities handling medical waste are inefficient due to overuse and poor maintenance and discharge directly into rivers. This study aimed to investigate the identity and estimates the concentration of phthalates in supposed treated medical wastes from a hospital sewer and water from a receiving river. Samples were randomly collected before and after treatment by the sewer plants, while samples were randomly collected along the course of the river starting from point of discharge. Control samples were taken from upstream about 500 m along the river course. The samples were extracted by liquid-liquid chroma- tographic process using dichloromethane, after which they were cleaned up in a column of silica gel using hexane as the mobile solvent. The cleaned extracts were analyzed by HPLC. The concentrations (μg/L) of dimethyl-, diethyl-, diphenyl-, dibutyl- and di-(2-ethyl)hexyl phthalates ranged from 62.81 ± 18.53;4.74 ± 3.57;2.05 ± 1.80;11.40 ± 5.58 to 141.92 ± 35.8 respectively in the sewer waste. The receiving river had a concentration (μg/L) of 9.17 ± 14.02;0.18 ± 0.31;0.48 ± 0.84;2.84 ± 1.21;61.72 ± 38.35 respectively for dimethyl-, diethyl-, diphenyl-, dibutyl- and di-(2-ethyl) hexyl phthalates. These concentrations were higher than control and far exceeded the USEPA limits of 3 μg/l recom- mended for phthalates in water. Contaminants of aquatic environment by untreated wastes from hospitals has serious implications on public health and environment as human risks for phthalate esters downstream are high and this calls for urgent need to develop strategy to build incentives for compliance in treatment and discharge of wastes into river waters.
文摘The study assesses the spatial distribution and sources of mercury contamination in the Ankobra River Basin in southwestern Ghana and discusses possible remediation options and challenges. Eighty-two (82) samples of water and streambed sediments from areas of active and historic artisanal mining and historic mine spoil from large-scale mining were analysed for their total mercury content using cold vapour Atomic Fluorescence Spectrometry (CV-AAS). The highest Hg concentrations were recorded from historic mine tailings, legacy of large scale mines in the area, which averaged 795 ppb but ranged from 80 ppb to 2500 ppb. Concentrations in streambed sediments averaged 139 ppb, but ranged from 63 ppb to 270 ppb. Water, expectedly, gave the lowest Hg concentrations with a mean value of 1.5 ppb, but ranged from below detection to 8 ppb. Areas worked by artisanal miners and historic tailings dumps at Bondaye and Prestea recorded the highest mercury values. These high mercury concentration sites constitute potential sources of major mercury pollution in the area and therefore require major and urgent clean up to mitigate any major health risks. However, any remediation strategy would require further and detailed study of the contaminated sites and an evaluation of known remediation techniques to achieve maximum results.
