The metabolism of copper and arsenic in a copper pyrometallurgy process was studied through substance flow analysis method.The mass balance accounts and substance flow charts of copper and arsenic were established,ind...The metabolism of copper and arsenic in a copper pyrometallurgy process was studied through substance flow analysis method.The mass balance accounts and substance flow charts of copper and arsenic were established,indicators including direct recovery,waste recycle ratio,and resource efficiency were used to evaluate the metabolism efficiency of the system.The results showed that,the resource efficiency of copper was 97.58%,the direct recovery of copper in smelting,converting,and refining processes was 91.96%,97.13%and 99.47%,respectively.Meanwhile,for producing 1 t of copper,10 kg of arsenic was carried into the system,with the generation of 1.07 kg of arsenic in flotation tailing,8.50 kg of arsenic in arsenic waste residue,and 0.05 kg of arsenic in waste water.The distribution and transformation behaviors of arsenic in the smelting,converting,and refining processes were also analyzed,and some recommendations for improving copper resource efficiency and pollution control were proposed based on substance flow analysis.展开更多
That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concept...That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concepts of the chain and the chain group of product life cycles, which are essential for understanding the specific features of substance flow, were advanced. Taking the specific feature of substance flow into consideration, on the analogy of the two approaches in fluid mechanics, two approaches of substance flow analysis, i.e. L method and E model, were formulated. Illustrative models of steady and unsteady substance flow were sketched by both methods, and comparison between them was made in general.展开更多
Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated ...Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated to be 1.89×10^6 t, which were mainly from use （39.20%） and waste management＆recycling （33.13%）. The accumulative lead in 1960-2010 from the anthropogenic flow was estimated and the results show that the total accumulative lead in this period amounted to 19.54×10^6 t, which was equivalent to 14.26 kg and 2.04 g/m^2 at the present population and territory.展开更多
Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective appro...Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.展开更多
This paper discusses the use of substance flow analysis （SFA） as a tool to support quantified research on urban drainage systems. Based on the principle of mass balance, a static substance flow model is established ...This paper discusses the use of substance flow analysis （SFA） as a tool to support quantified research on urban drainage systems. Based on the principle of mass balance, a static substance flow model is established to describe and examine the routes and intensities of water, chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） for a representative hypothetical city （RH city） in China, which is a devised and scaled city using statistical characteristics of urban circumstances at the national level. It is estimated that the annual flux of water, COD, TN and TP through the urban drainage system in 2010 was 55.1 million m3, 16037.3 t, 1649.5 t and 209.7 t, respectively. The effluent of wastewater treatment plant （WWTP） was identified as the most important pathway for pollutant emissions, which con- tributed approximately 60% of COD, 65% of TN and 50% of TP to receiving water. During the wastewater treatment process, 1.0 million m3, 7042.5 t, 584.2 t and 161.4 t of the four studied substances had been transmitted into sludge, meanwhile 3813.0 t of COD and 394.0 t of TN were converted and emitted to the atmosphere. Compared with the representative hypothetical city of 2000, urban population and the area of urban built districts had expanded by approximately 90% and 80% respectively during the decade, resulting in a more than threefold increase in the input of substances into the urban drainage system. Thanks to the development of urban drainage systems, the total loads of the city were maintained at a similar level.展开更多
In this study,the metabolism of a hydrometallurgical process for tungsten extracting from wolframite was studied through substance flow analysis.The mass balance accounts,substance flow charts of tungsten and arsenic ...In this study,the metabolism of a hydrometallurgical process for tungsten extracting from wolframite was studied through substance flow analysis.The mass balance accounts,substance flow charts of tungsten and arsenic were established to evaluate the metabolism efficiency of the investigated system.The results showed that,the total tungsten resource efficiency of the system was 97.56%,and the tungsten recovery of unit process autoclaved alkali leaching,ion exchange,Mo removing,concentration and crystallization was 98.16%,98.94%,99.71%,99.89%,respectively.Meanwhile,for extracting 1 ton of tungsten into the qualified ammonium paratungstate,10.0414 kg of arsenic was carried into the system,with the generation of 7.2801 kg of arsenic in alkali leaching residue,1.5067 kg of tungsten in arsenic waste residue,and 1.2312 kg of tungsten in Mo residue.Besides,7.9 g of arsenic was discharged into nature environment with waste water,15.5 g of arsenic was entrained into the final APT.The distribution and transformation behaviors of arsenic during production were analyzed through phases change analysis,and some recommendations for improving the resource efficiency of tungsten and pollution control during production were also proposed based on the substance flow analysis in this study.展开更多
Vanadium is a vital strategic resource, and vanadium metabolism is an important part of the national socio-economic system of China. This study conducts accounting and scenario analysis on the life cycle of vanadium m...Vanadium is a vital strategic resource, and vanadium metabolism is an important part of the national socio-economic system of China. This study conducts accounting and scenario analysis on the life cycle of vanadium metabolism in China. Based on the character- istics of vanadium life cycle and substance flow analysis （SFA） framework, we present a quantitative evaluation of a static anthropogenic vanadium life cycle for the year 2010. Results show that anthropogenic vanadium consumption, stocks, and new domestic scrap are at 98.2, 21.2, and 4.1 kt, respectively; new scrap is usually discarded. The overall utilization ratio of vanadium is 32.2%. A large amount of vanadium is stockpiled into tailings, debris, slags, and other spent solids. A scenario analysis was conducted to analyze the future developmental trend of vanadium metabolism in China based on the SFA frame- work and the qualitative analysis of technology advance- ment and socio-economic development. The baseline year was set as 2010. Several indicators were proposed to simulate different scenarios from 2010 to 2030. The scenario analysis indicates that the next 20 years is a critical period for the vanadium industry in China. This paper discusses relevant policies that contribute to the improvement of sustainable vanadium utilization in China.展开更多
Research on carbon cycling has attracted attention from both scientists and policy-makers. Based on material flow analysis, this study systematically budgets the carbon inputs, outputs and balance from 1980 to 2013 fo...Research on carbon cycling has attracted attention from both scientists and policy-makers. Based on material flow analysis, this study systematically budgets the carbon inputs, outputs and balance from 1980 to 2013 for China＇s agro-ecosystem and its sub-systems, including agricultural land use, livestock breeding and rural life. The results show that from 1980 to 2013, both the carbon input and output were growing gradually, with the carbon input doubling from 1.6 Pg C/year in 1980 to 3.4 Pg C/year in 2013, while carbon output grew from 2.2 Pg C/year in 1980 to 3.8 Pg C/year in 2013. From 1980 to 2013, the crop production system in China has remained a carbon source, and the agricultural land uses were also almost all carbon sources instead of carbon sinks. As soil carbon stock plays a very important role in deciding the function of China＇s agro-ecosystem as a carbon sink or source, practices that can promote carbon storage and sequestration will be an essential component of low carbon agriculture development in China.展开更多
Germanium,a critical yet often overlooked metal,has experienced significant shifts in its global market,largely driven by China’s dominant role.However,concerns are growing over the sustainability of germanium supply...Germanium,a critical yet often overlooked metal,has experienced significant shifts in its global market,largely driven by China’s dominant role.However,concerns are growing over the sustainability of germanium supply in China due to imbalances in mining,manufacturing,recycling,and rising demand.In this study,we employ substance flow analysis to provide a quantitative assessment of China’s germanium flow system in 2019,and we project future demand and anthropogenic mineral generation up to 2050 using stock-driven models.Our results indicate that by 2050,domestic demand for germanium will increase to 164–187 t—double the demand in 2019—with infrared optics and solar cells being the primary drivers.A supply shortage is anticipated before 2040,although recycling through urban mining could meet around 30%of the demand.These findings underscore the urgent need to address emerging supply challenges and offer critical insights for policymakers and stakeholders to inform strategic decision-making.展开更多
Metal,as the indispensable material,is functioning the society from technology to the environment.Niobium(Nb)is considered a unique earth metal as it is related to many emerging technologies.The increasing economic gr...Metal,as the indispensable material,is functioning the society from technology to the environment.Niobium(Nb)is considered a unique earth metal as it is related to many emerging technologies.The increasing economic growth exerts an increasing pressure on supply,which leads to its significance in the economic sector.However,few papers have addressed Nb sustainability,which forms the scope of this paper in order to start the process of Nb market forecasting based on some previous data and some assumptions.Therefore,this paper will discuss different thoughts in material substitution and the substance flow of Nb throughout a static flow using Nb global data to have a better understanding of the process of Nb from production to end of life.This shall lead to the identification of the market needs to determine its growth which is around 2.5% to 3.0%.Moreover,due to China’s huge Nb consumption which comes from the continuous development that is happening over the years,it will also briefly mention the Nb situation as well as its growth which according to statistics will grow steadily till 2030 by a rate of 4.0% to 6.0%.The results show that there should be some enhancement to Nb recycling potentials out of steel scrap.In addition,there should be more involvement of Nb in different industries as this would lead to less-used materials which can be translated to less environmental impact.展开更多
China has become the largest producer of crude steel in the world since 1996, which places the country under huge pressure in terms of resources, energy, and the environment. Examining the driver of steel demand is of...China has become the largest producer of crude steel in the world since 1996, which places the country under huge pressure in terms of resources, energy, and the environment. Examining the driver of steel demand is of great significance to the structural adjustment and sustainable development of the steel industry. The researchers calculate the steel demand in China from 2000 to 2009 based on three sinks （steel stock, export, and loss） by taking the four stages of steel life cycle （production, fabrication and manufacturing, use, and waste manage- ment and recycling） as the study object. The researchers conclude that addition to in-use stock is the main driver of steel demand and that the 10-year average addition to in- use stock accounted for 77% of the steel sinks, in which 55% of the addition occurs in the building sector, and the steel for this segment is of low strength with large consumption. Based on the analysis of existing policies, the researchers propose that the steel demand structure will develop toward diversification and that the building sector will realize the upgrade of products as soon as possible to improve construction quality. Under the pressure of rising cost for imported resources, the export ratio of steel products should be controlled appropriately. Thus, recy- cling economy should be developed to reduce steel losses.展开更多
Three-dimensional fluorescence excitation–emission matrix（EEM） coupled with parallel factor analysis（PARAFAC） was performed for a total of 18 water samples taken from three water sources（two lakes and one wastew...Three-dimensional fluorescence excitation–emission matrix（EEM） coupled with parallel factor analysis（PARAFAC） was performed for a total of 18 water samples taken from three water sources（two lakes and one wastewater treatment plant（WWTP） secondary effluent）,with the purpose of identifying the major ultrafiltration（UF） membrane foulants in different water sources. Three fluorescent components（C1, C2 and C3） were identified,which represented terrestrially derived humic-like substances（C1）, microbially derived humic-like substances（C2）, and protein-like substances（C3）. The correlations between the different fluorescent components and UF membrane fouling were analyzed. It was shown that for the WWTP secondary effluent, all three components（C1, C2 and C3） made a considerable contribution to the irreversible and total fouling of the UF membrane.However, for the two lakes, only the C3 exhibited a strong correlation with membrane fouling, indicating that the protein-like substances were the major membrane foulants in the lake waters. Significant attachment of C1, C2 and C3 to the UF membrane was also confirmed by mass balance analyses for the WWTP secondary effluent; while the attachment of C1 and C2 was shown to be negligible for the two lakes. The results may provide basic formation for developing suitable fouling control strategies for sustainable UF processes.展开更多
Millions of tons of waste activated sludge（WAS） produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critica...Millions of tons of waste activated sludge（WAS） produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants（WWTPs） of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples（up to 9478 mg/L）, followed by endogenous residues（6736 mg/L）,extracellular polymeric substances（2088 mg/L）, and intracellular storage products（464 mg/L）among others. Moreover, significant differences（p 〈 0.05） were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge.展开更多
基金financial supports from the National Key R&D Program of China(No.2019YFC1907400)the National Natural Science Foundation of China(Nos.51904351,51620105013)。
文摘The metabolism of copper and arsenic in a copper pyrometallurgy process was studied through substance flow analysis method.The mass balance accounts and substance flow charts of copper and arsenic were established,indicators including direct recovery,waste recycle ratio,and resource efficiency were used to evaluate the metabolism efficiency of the system.The results showed that,the resource efficiency of copper was 97.58%,the direct recovery of copper in smelting,converting,and refining processes was 91.96%,97.13%and 99.47%,respectively.Meanwhile,for producing 1 t of copper,10 kg of arsenic was carried into the system,with the generation of 1.07 kg of arsenic in flotation tailing,8.50 kg of arsenic in arsenic waste residue,and 0.05 kg of arsenic in waste water.The distribution and transformation behaviors of arsenic in the smelting,converting,and refining processes were also analyzed,and some recommendations for improving copper resource efficiency and pollution control were proposed based on substance flow analysis.
文摘That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concepts of the chain and the chain group of product life cycles, which are essential for understanding the specific features of substance flow, were advanced. Taking the specific feature of substance flow into consideration, on the analogy of the two approaches in fluid mechanics, two approaches of substance flow analysis, i.e. L method and E model, were formulated. Illustrative models of steady and unsteady substance flow were sketched by both methods, and comparison between them was made in general.
基金Project (41171361) supported by the National Natural Science Foundation of China
文摘Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated to be 1.89×10^6 t, which were mainly from use （39.20%） and waste management＆recycling （33.13%）. The accumulative lead in 1960-2010 from the anthropogenic flow was estimated and the results show that the total accumulative lead in this period amounted to 19.54×10^6 t, which was equivalent to 14.26 kg and 2.04 g/m^2 at the present population and territory.
基金supported by the National Natural Science Foundation of China(32301453 and 3272675)the China Postdoctoral Science Foundation(2023M730682)。
文摘Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.
文摘This paper discusses the use of substance flow analysis （SFA） as a tool to support quantified research on urban drainage systems. Based on the principle of mass balance, a static substance flow model is established to describe and examine the routes and intensities of water, chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） for a representative hypothetical city （RH city） in China, which is a devised and scaled city using statistical characteristics of urban circumstances at the national level. It is estimated that the annual flux of water, COD, TN and TP through the urban drainage system in 2010 was 55.1 million m3, 16037.3 t, 1649.5 t and 209.7 t, respectively. The effluent of wastewater treatment plant （WWTP） was identified as the most important pathway for pollutant emissions, which con- tributed approximately 60% of COD, 65% of TN and 50% of TP to receiving water. During the wastewater treatment process, 1.0 million m3, 7042.5 t, 584.2 t and 161.4 t of the four studied substances had been transmitted into sludge, meanwhile 3813.0 t of COD and 394.0 t of TN were converted and emitted to the atmosphere. Compared with the representative hypothetical city of 2000, urban population and the area of urban built districts had expanded by approximately 90% and 80% respectively during the decade, resulting in a more than threefold increase in the input of substances into the urban drainage system. Thanks to the development of urban drainage systems, the total loads of the city were maintained at a similar level.
基金financially supported by the National Key R&D Program of China(Grant No.2019YFC1907400)the National Natural Science Foundation of China(Grant Nos.51904351 and 51620105013)
文摘In this study,the metabolism of a hydrometallurgical process for tungsten extracting from wolframite was studied through substance flow analysis.The mass balance accounts,substance flow charts of tungsten and arsenic were established to evaluate the metabolism efficiency of the investigated system.The results showed that,the total tungsten resource efficiency of the system was 97.56%,and the tungsten recovery of unit process autoclaved alkali leaching,ion exchange,Mo removing,concentration and crystallization was 98.16%,98.94%,99.71%,99.89%,respectively.Meanwhile,for extracting 1 ton of tungsten into the qualified ammonium paratungstate,10.0414 kg of arsenic was carried into the system,with the generation of 7.2801 kg of arsenic in alkali leaching residue,1.5067 kg of tungsten in arsenic waste residue,and 1.2312 kg of tungsten in Mo residue.Besides,7.9 g of arsenic was discharged into nature environment with waste water,15.5 g of arsenic was entrained into the final APT.The distribution and transformation behaviors of arsenic during production were analyzed through phases change analysis,and some recommendations for improving the resource efficiency of tungsten and pollution control during production were also proposed based on the substance flow analysis in this study.
文摘Vanadium is a vital strategic resource, and vanadium metabolism is an important part of the national socio-economic system of China. This study conducts accounting and scenario analysis on the life cycle of vanadium metabolism in China. Based on the character- istics of vanadium life cycle and substance flow analysis （SFA） framework, we present a quantitative evaluation of a static anthropogenic vanadium life cycle for the year 2010. Results show that anthropogenic vanadium consumption, stocks, and new domestic scrap are at 98.2, 21.2, and 4.1 kt, respectively; new scrap is usually discarded. The overall utilization ratio of vanadium is 32.2%. A large amount of vanadium is stockpiled into tailings, debris, slags, and other spent solids. A scenario analysis was conducted to analyze the future developmental trend of vanadium metabolism in China based on the SFA frame- work and the qualitative analysis of technology advance- ment and socio-economic development. The baseline year was set as 2010. Several indicators were proposed to simulate different scenarios from 2010 to 2030. The scenario analysis indicates that the next 20 years is a critical period for the vanadium industry in China. This paper discusses relevant policies that contribute to the improvement of sustainable vanadium utilization in China.
基金supported by the National Science & Technology Pillar Program during the 12th Five-year Plan Period (No. 2013BAD11B03)the National Natural Science Foundation of China (Nos. 71573260,71273153,and 71525007)the Basic Scientific Research Fund (No. BSRF201311) for National Nonprofit Institutes from Ministry of Agriculture(MoA),China
文摘Research on carbon cycling has attracted attention from both scientists and policy-makers. Based on material flow analysis, this study systematically budgets the carbon inputs, outputs and balance from 1980 to 2013 for China＇s agro-ecosystem and its sub-systems, including agricultural land use, livestock breeding and rural life. The results show that from 1980 to 2013, both the carbon input and output were growing gradually, with the carbon input doubling from 1.6 Pg C/year in 1980 to 3.4 Pg C/year in 2013, while carbon output grew from 2.2 Pg C/year in 1980 to 3.8 Pg C/year in 2013. From 1980 to 2013, the crop production system in China has remained a carbon source, and the agricultural land uses were also almost all carbon sources instead of carbon sinks. As soil carbon stock plays a very important role in deciding the function of China＇s agro-ecosystem as a carbon sink or source, practices that can promote carbon storage and sequestration will be an essential component of low carbon agriculture development in China.
基金financially supported by the National Natural Sciences Foundation of China(No.92062111)the National Key Technology R&D Program of China(No.2019YFC1908501).
文摘Germanium,a critical yet often overlooked metal,has experienced significant shifts in its global market,largely driven by China’s dominant role.However,concerns are growing over the sustainability of germanium supply in China due to imbalances in mining,manufacturing,recycling,and rising demand.In this study,we employ substance flow analysis to provide a quantitative assessment of China’s germanium flow system in 2019,and we project future demand and anthropogenic mineral generation up to 2050 using stock-driven models.Our results indicate that by 2050,domestic demand for germanium will increase to 164–187 t—double the demand in 2019—with infrared optics and solar cells being the primary drivers.A supply shortage is anticipated before 2040,although recycling through urban mining could meet around 30%of the demand.These findings underscore the urgent need to address emerging supply challenges and offer critical insights for policymakers and stakeholders to inform strategic decision-making.
基金supported by the National Natural Science Foundation of China(Grant No.92062111)the National Key R&D Program of China(Grant No.2019YFC1903711).
文摘Metal,as the indispensable material,is functioning the society from technology to the environment.Niobium(Nb)is considered a unique earth metal as it is related to many emerging technologies.The increasing economic growth exerts an increasing pressure on supply,which leads to its significance in the economic sector.However,few papers have addressed Nb sustainability,which forms the scope of this paper in order to start the process of Nb market forecasting based on some previous data and some assumptions.Therefore,this paper will discuss different thoughts in material substitution and the substance flow of Nb throughout a static flow using Nb global data to have a better understanding of the process of Nb from production to end of life.This shall lead to the identification of the market needs to determine its growth which is around 2.5% to 3.0%.Moreover,due to China’s huge Nb consumption which comes from the continuous development that is happening over the years,it will also briefly mention the Nb situation as well as its growth which according to statistics will grow steadily till 2030 by a rate of 4.0% to 6.0%.The results show that there should be some enhancement to Nb recycling potentials out of steel scrap.In addition,there should be more involvement of Nb in different industries as this would lead to less-used materials which can be translated to less environmental impact.
基金We deeply appreciate the capital support given by the China Postdoctoral Science Foundation （20110490425）, the diligent work of data collectors, and the enlightenment provided by the SFA pioneers.
文摘China has become the largest producer of crude steel in the world since 1996, which places the country under huge pressure in terms of resources, energy, and the environment. Examining the driver of steel demand is of great significance to the structural adjustment and sustainable development of the steel industry. The researchers calculate the steel demand in China from 2000 to 2009 based on three sinks （steel stock, export, and loss） by taking the four stages of steel life cycle （production, fabrication and manufacturing, use, and waste manage- ment and recycling） as the study object. The researchers conclude that addition to in-use stock is the main driver of steel demand and that the 10-year average addition to in- use stock accounted for 77% of the steel sinks, in which 55% of the addition occurs in the building sector, and the steel for this segment is of low strength with large consumption. Based on the analysis of existing policies, the researchers propose that the steel demand structure will develop toward diversification and that the building sector will realize the upgrade of products as soon as possible to improve construction quality. Under the pressure of rising cost for imported resources, the export ratio of steel products should be controlled appropriately. Thus, recy- cling economy should be developed to reduce steel losses.
基金supported by the National Natural Science Foundation of China(No.51208140)the National Water Pollution Control and Treatment Science and Technology Major Project of China(No.2012ZX07201002)
文摘Three-dimensional fluorescence excitation–emission matrix（EEM） coupled with parallel factor analysis（PARAFAC） was performed for a total of 18 water samples taken from three water sources（two lakes and one wastewater treatment plant（WWTP） secondary effluent）,with the purpose of identifying the major ultrafiltration（UF） membrane foulants in different water sources. Three fluorescent components（C1, C2 and C3） were identified,which represented terrestrially derived humic-like substances（C1）, microbially derived humic-like substances（C2）, and protein-like substances（C3）. The correlations between the different fluorescent components and UF membrane fouling were analyzed. It was shown that for the WWTP secondary effluent, all three components（C1, C2 and C3） made a considerable contribution to the irreversible and total fouling of the UF membrane.However, for the two lakes, only the C3 exhibited a strong correlation with membrane fouling, indicating that the protein-like substances were the major membrane foulants in the lake waters. Significant attachment of C1, C2 and C3 to the UF membrane was also confirmed by mass balance analyses for the WWTP secondary effluent; while the attachment of C1 and C2 was shown to be negligible for the two lakes. The results may provide basic formation for developing suitable fouling control strategies for sustainable UF processes.
基金supported by the National Natural Science Foundation of China(Nos.51408589 and 51138009)State Key Joint Laboratory of Environment Simulation and Pollution Control of China(Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,No.14Z03ESPCR)Youth Innovation Promotion Association of the Chinese Academy of Sciences
文摘Millions of tons of waste activated sludge（WAS） produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants（WWTPs） of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples（up to 9478 mg/L）, followed by endogenous residues（6736 mg/L）,extracellular polymeric substances（2088 mg/L）, and intracellular storage products（464 mg/L）among others. Moreover, significant differences（p 〈 0.05） were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge.
