The study of transient heat conduction in multilayered slabs is widely used in various engineering fields. In this paper, the transient heat conduction in multilayered slabs with general boundary conditions and arbitr...The study of transient heat conduction in multilayered slabs is widely used in various engineering fields. In this paper, the transient heat conduction in multilayered slabs with general boundary conditions and arbitrary heat generations is analysed. The boundary conditions are general and include various combinations of Dirichlet, Neumann or Robin boundary conditions at either surface. Moreover, arbitrary heat generations in the slabs are taken into account. The solutions are derived by basic methods, including the superposition method, separation variable method and orthogonal expansion method. The simplified double-layered analytical solution is validated by a numerical method and applied to predicting the temporal and spatial distribution of the temperature inside a landfill. It indicates the ability of the proposed analytical solutions for solving the wide range of applied transient heat conduction problems.展开更多
The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactiv...The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.展开更多
Surface mining operations extract a large quantity of waste material,which is generally disposed into a dump area.This waste can cause a series of environmental problems ranging from landscape deterioration to acidic ...Surface mining operations extract a large quantity of waste material,which is generally disposed into a dump area.This waste can cause a series of environmental problems ranging from landscape deterioration to acidic water generation and water pollution.Therefore,mine waste management is a significant task in mining operations.As known,in strip mining,the overburden is not transported to waste dumps but disposed directly into adjacent strip which was mined out.This concept can be adapted for mine planning of relatively horizontal deposits through a mixed integer programming(MIP)model.The main idea behind this work is that,in one pit,production voids created in early year of mining are used for waste landfilling in late years of production.In other words,in addition to external dumping,a landfilling option within the same pit is proposed for mine design optimization.The problem is formulated as maximization of the net present value(NPV)of the mining project under the constraints of access,landfill waste handling,mining and processing capacities.A case study using a data set was carried out to see the performance of the proposed approach.The findings showed that this approach could be used in waste management incorporating a landfilling option into mine planning.As a result,material handling costs decrease,and environmental compliance increases due to less external waste quantity.展开更多
The experiment was conducted to treat the leachate from two simulating columns by recycling to the columns themselves without being discharged into the enviroment. The columns were employed to simulate anaerobic and s...The experiment was conducted to treat the leachate from two simulating columns by recycling to the columns themselves without being discharged into the enviroment. The columns were employed to simulate anaerobic and semi-aerobic landfills separately. The influence of landfill structure on stabilization of fully recycled leachate was studied. The results show that semi-aerobic landfill structure accelerates the stabilization of leachate recycled. The full recycle of leachate in semi-aerobic landfill is a very feasible and effective technology for leachate treatment with low cost and energy saving especially in arid and rare rainfall regions. Meanwhile, the environmental impact of landfill can be greatly minimized.展开更多
Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological m...Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological model.of water flow and a hydrodynamic model of contaminant are presented to simulate the migration of leachate through clay-solidified grouting curtain in MSW landfills, with particular attention paid to the role of diffusive and adsorptive fluxes in contaminant transport. The models were applied to simulate the sensitivity of the curtain's behavior to changes in parameters, such as thickness, depth, permeability coefficient, diffusion coefficient,resistance coefficient and concentration, and also to demonstrate the contaminant distribution on the evolution of travel time and offset distance of clay-solidified grouting curtain in landfills. It is found that a part of leachate components stays or is retarded in clay-solidified grouting curtain by precipitate or exchange, the retention rate is closely related to composition of clay-solidified grouting curtain, more than 800%, and the maximum occurs at the cementclay ratio of 2: 4 under experimental conditions. Contamination distribution is variable on travel time and offset distance, the highest concentration takes place where the contamination intensity is nearest to the pollution resource or takes place at early middle period of transport, and the pollutant attenuates gradually. The results indicate that claysolidified grouting curtain with a proper thickness, a low permeability coefficient and a high resistance coefficient might serve as a sufficiently effective vertical barrier against leachate seepage and contamination migration in MSWlandfills.展开更多
Due to rainwater and surface water infiltration, leachate generated by buried landfill can result in the secondary pollution of groundwater.In this study, combination technologies of chemical coagulation and electroch...Due to rainwater and surface water infiltration, leachate generated by buried landfill can result in the secondary pollution of groundwater.In this study, combination technologies of chemical coagulation and electrochemistry were used to treat landfill leachate.First,experiments were carried out with Ca（OH）<sub>2</sub> and FeCl<sub>3</sub> as the flocculant to pre-treat landfill leachate.The optimum treatment conditions are as follows:the dosages of Ca（OH）<sub>2</sub> and FeCl<sub>3</sub> are 17 g/L and 17 mL/L,respectively;mixing time is 5min,and the 86.8%of COD<sub>Cr</sub>,38.6%of NH<sub>3</sub>-N and 93.2%of phosphorus were removed(COD<sub>Cr</sub>,NH<sub>3</sub>展开更多
Nowadays,a certain amount of landfills in China were constructed without horizontal liner system.The research conducted focuses mainly on the contaminants from landfill leachate migrating in the aquifer of a fractured...Nowadays,a certain amount of landfills in China were constructed without horizontal liner system.The research conducted focuses mainly on the contaminants from landfill leachate migrating in the aquifer of a fractured granite area,and pollution predictions for groundwater were made by establishing numerical model with Visual Modflow combining field investigation like geological surveys,drilling,geophysical explorations,hydrogeological experiments,water quality analysis.The transportation of the chloride ion from landfill in the aquifer was simulated in the model with time frames of 2 555,3 650,5 475 and7 300 d.The model shows that from 2 555 d to 7 300 d starting from 2003,the chloride ion migrated from 900 m to 1 300 m,respectively,along the groundwater flow.The results indicate that as leachate plume migrated in the aquifer,the concentration of the pollutants can be up to 19.74 to 251.76 times that of background value.The research proves that the leachate poses a threat to the local water body and offers a reference towards groundwater pollution prevention for fractured granite landfill sites.展开更多
Based on the degradation characteristics of municipal solid waste(MSW)in China,the traditional anaerobic sequencing batch bioreactor landfill(ASBRL)was optimized,and an improved anaerobic sequencing batch bioreactor l...Based on the degradation characteristics of municipal solid waste(MSW)in China,the traditional anaerobic sequencing batch bioreactor landfill(ASBRL)was optimized,and an improved anaerobic sequencing batch bioreactor landfill(IASBRL)was put forward on the basis of leachate self-recirculation.By monitoring MSW composition,leachate characteristics variation and landfill gas(LFG)generation,the effect of IASBRL was comparatively studied by simulation landfill.Based on the adjusting,scouring and carrying effects of leachate self-recirculation,IASBRL can rapidly decrease Eh value to about-500mV and form a suitable biochemical environment for methanogens,which provides a precondition for stable cooperation between non-methanogens and methanogens.IASBRL can avoid the accumulation of organic acids,make VFA(volatile fatty acid)concentration and CODCr decrease along with the small range fluctuations,and form a stable decomposition-consumption synergy during MSW degradation,therefore,the hydrolysis rate of easy hydrolyze material reaches 71.2% in IASBRL.From the viewpoint of LFG resources in IASBRL,the cumulative LFG production increases to 2327.0L,CH4 mass fraction stabilizes at about 50%,and these provide a favorable precondition for LFG development.展开更多
Large amounts of ammonium and a low content of biodegradable chemical oxygen demand（COD） are contained in leachate from aged landfills, together with the effluent containing high concentration of nitric nitrogen aft...Large amounts of ammonium and a low content of biodegradable chemical oxygen demand（COD） are contained in leachate from aged landfills, together with the effluent containing high concentration of nitric nitrogen after biochemical treatment. Treatment effect of anaerobic ammonium oxidation （anammox） process on the mixture of the leachate and its biochemical effluent was investigated. The results show that the average removal efficiencies of ammonium, nitric nitrogen and total nitrogen are 87.51%, 74.95% and 79.59%, respectively, corresponding to the average ratio of removed nitric nitrogen to ammonium, i.e. 1.14 during the steady phase of anammox activity. The mean removal efficiency of COD is only 24.01% during the experimental period. Thc,dcmand of total phosphorous for the anammox process is unobvious. Especially, the alkalinity and pH value of the effluent are close to those of the inftuent during the steady phase of anammox activity. In addition, it is demonstrated that the status of the anammox bioreactor can be indicated by the alkalinity and pH value during the course of the experiment. The anammox bioreactor has shown potential for nitrogen removal in the leachate mixture. However, COD and total phosphorous in the leachate mixture need further treatment for removal efficiencies of COD and total phosphorous are not good in the anammox bioreactor.展开更多
Full scale experimental study on nitrogen removal for low-carbon wastewater was conducted in reversed A2/O process in Jiguanshi waste water treatment plant in Chongqing,in order to aid the operation and maintenance of...Full scale experimental study on nitrogen removal for low-carbon wastewater was conducted in reversed A2/O process in Jiguanshi waste water treatment plant in Chongqing,in order to aid the operation and maintenance of similar WWTP. When the proposed measures,such as using 0.1% (volume fraction of wastewater) landfill leachate,shortening HRT by 2/3 in the primary sedimentation tank and controlling DO at 0.5 mg/L in the 3rd section of aerobic zone,are applied,15% of the carbon source can be complemented,the favorable property of activated sludge is achieved,and the nitrogen removal effect is significantly improved. The effluent NH3-N is 2 mg/L and the removal rate is 90%. The effluent TN is 17 mg/L and the removal rate is 54%. The up-to-standard discharge of the effluent is achieved. And after the optimization,the unit electricity consumption also reaches 0.21 kW/h and saves 20%.展开更多
Landfill leaks pose a serious threat to environmental health,risking the contamination of both groundwater and soil resources.Accurate investigation of these sites is essential for implementing effective prevention an...Landfill leaks pose a serious threat to environmental health,risking the contamination of both groundwater and soil resources.Accurate investigation of these sites is essential for implementing effective prevention and control measures.The self-potential(SP)stands out for its sensitivity to contamination plumes,offering a solution for monitoring and detecting the movement and seepage of subsurface pollutants.However,traditional SP inversion techniques heavily rely on precise subsurface resistivity information.In this study,we propose the Attention U-Net deep learning network for rapid SP inversion.By incorporating an attention mechanism,this algorithm effectively learns the relationship between array-style SP data and the location and extent of subsurface contaminated sources.We designed a synthetic landfill model with a heterogeneous resistivity structure to assess the performance of Attention U-Net deep learning network.Additionally,we conducted further validation using a laboratory model to assess its practical applicability.The results demonstrate that the algorithm is not solely dependent on resistivity information,enabling effective locating of the source distribution,even in models with intricate subsurface structures.Our work provides a promising tool for SP data processing,enhancing the applicability of this method in the field of near-subsurface environmental monitoring.展开更多
基金Projects(41530637,41877222,41702290)supported by the National Natural Science Foundation of China
文摘The study of transient heat conduction in multilayered slabs is widely used in various engineering fields. In this paper, the transient heat conduction in multilayered slabs with general boundary conditions and arbitrary heat generations is analysed. The boundary conditions are general and include various combinations of Dirichlet, Neumann or Robin boundary conditions at either surface. Moreover, arbitrary heat generations in the slabs are taken into account. The solutions are derived by basic methods, including the superposition method, separation variable method and orthogonal expansion method. The simplified double-layered analytical solution is validated by a numerical method and applied to predicting the temporal and spatial distribution of the temperature inside a landfill. It indicates the ability of the proposed analytical solutions for solving the wide range of applied transient heat conduction problems.
文摘The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.
文摘Surface mining operations extract a large quantity of waste material,which is generally disposed into a dump area.This waste can cause a series of environmental problems ranging from landscape deterioration to acidic water generation and water pollution.Therefore,mine waste management is a significant task in mining operations.As known,in strip mining,the overburden is not transported to waste dumps but disposed directly into adjacent strip which was mined out.This concept can be adapted for mine planning of relatively horizontal deposits through a mixed integer programming(MIP)model.The main idea behind this work is that,in one pit,production voids created in early year of mining are used for waste landfilling in late years of production.In other words,in addition to external dumping,a landfilling option within the same pit is proposed for mine design optimization.The problem is formulated as maximization of the net present value(NPV)of the mining project under the constraints of access,landfill waste handling,mining and processing capacities.A case study using a data set was carried out to see the performance of the proposed approach.The findings showed that this approach could be used in waste management incorporating a landfilling option into mine planning.As a result,material handling costs decrease,and environmental compliance increases due to less external waste quantity.
基金Project(2003-MOC-NGGP-03) supported by the Netherlands Government Grant Project
文摘The experiment was conducted to treat the leachate from two simulating columns by recycling to the columns themselves without being discharged into the enviroment. The columns were employed to simulate anaerobic and semi-aerobic landfills separately. The influence of landfill structure on stabilization of fully recycled leachate was studied. The results show that semi-aerobic landfill structure accelerates the stabilization of leachate recycled. The full recycle of leachate in semi-aerobic landfill is a very feasible and effective technology for leachate treatment with low cost and energy saving especially in arid and rare rainfall regions. Meanwhile, the environmental impact of landfill can be greatly minimized.
文摘Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological model.of water flow and a hydrodynamic model of contaminant are presented to simulate the migration of leachate through clay-solidified grouting curtain in MSW landfills, with particular attention paid to the role of diffusive and adsorptive fluxes in contaminant transport. The models were applied to simulate the sensitivity of the curtain's behavior to changes in parameters, such as thickness, depth, permeability coefficient, diffusion coefficient,resistance coefficient and concentration, and also to demonstrate the contaminant distribution on the evolution of travel time and offset distance of clay-solidified grouting curtain in landfills. It is found that a part of leachate components stays or is retarded in clay-solidified grouting curtain by precipitate or exchange, the retention rate is closely related to composition of clay-solidified grouting curtain, more than 800%, and the maximum occurs at the cementclay ratio of 2: 4 under experimental conditions. Contamination distribution is variable on travel time and offset distance, the highest concentration takes place where the contamination intensity is nearest to the pollution resource or takes place at early middle period of transport, and the pollutant attenuates gradually. The results indicate that claysolidified grouting curtain with a proper thickness, a low permeability coefficient and a high resistance coefficient might serve as a sufficiently effective vertical barrier against leachate seepage and contamination migration in MSWlandfills.
文摘Due to rainwater and surface water infiltration, leachate generated by buried landfill can result in the secondary pollution of groundwater.In this study, combination technologies of chemical coagulation and electrochemistry were used to treat landfill leachate.First,experiments were carried out with Ca（OH）<sub>2</sub> and FeCl<sub>3</sub> as the flocculant to pre-treat landfill leachate.The optimum treatment conditions are as follows:the dosages of Ca（OH）<sub>2</sub> and FeCl<sub>3</sub> are 17 g/L and 17 mL/L,respectively;mixing time is 5min,and the 86.8%of COD<sub>Cr</sub>,38.6%of NH<sub>3</sub>-N and 93.2%of phosphorus were removed(COD<sub>Cr</sub>,NH<sub>3</sub>
基金Project(12JJ305)supported by the Education Department of Hunan Province,China
文摘Nowadays,a certain amount of landfills in China were constructed without horizontal liner system.The research conducted focuses mainly on the contaminants from landfill leachate migrating in the aquifer of a fractured granite area,and pollution predictions for groundwater were made by establishing numerical model with Visual Modflow combining field investigation like geological surveys,drilling,geophysical explorations,hydrogeological experiments,water quality analysis.The transportation of the chloride ion from landfill in the aquifer was simulated in the model with time frames of 2 555,3 650,5 475 and7 300 d.The model shows that from 2 555 d to 7 300 d starting from 2003,the chloride ion migrated from 900 m to 1 300 m,respectively,along the groundwater flow.The results indicate that as leachate plume migrated in the aquifer,the concentration of the pollutants can be up to 19.74 to 251.76 times that of background value.The research proves that the leachate poses a threat to the local water body and offers a reference towards groundwater pollution prevention for fractured granite landfill sites.
基金Project(41072236)supported by the National Natural Science Foundation of ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,ChinaProject(2009A027)supported by Youth Research Foundation of China University of Mining and Technology
文摘Based on the degradation characteristics of municipal solid waste(MSW)in China,the traditional anaerobic sequencing batch bioreactor landfill(ASBRL)was optimized,and an improved anaerobic sequencing batch bioreactor landfill(IASBRL)was put forward on the basis of leachate self-recirculation.By monitoring MSW composition,leachate characteristics variation and landfill gas(LFG)generation,the effect of IASBRL was comparatively studied by simulation landfill.Based on the adjusting,scouring and carrying effects of leachate self-recirculation,IASBRL can rapidly decrease Eh value to about-500mV and form a suitable biochemical environment for methanogens,which provides a precondition for stable cooperation between non-methanogens and methanogens.IASBRL can avoid the accumulation of organic acids,make VFA(volatile fatty acid)concentration and CODCr decrease along with the small range fluctuations,and form a stable decomposition-consumption synergy during MSW degradation,therefore,the hydrolysis rate of easy hydrolyze material reaches 71.2% in IASBRL.From the viewpoint of LFG resources in IASBRL,the cumulative LFG production increases to 2327.0L,CH4 mass fraction stabilizes at about 50%,and these provide a favorable precondition for LFG development.
基金Project (20377013) supported by the National Natural Science Foundation of China project (020959) supported by Department of Science and Technology of Guangdong Province
文摘Large amounts of ammonium and a low content of biodegradable chemical oxygen demand（COD） are contained in leachate from aged landfills, together with the effluent containing high concentration of nitric nitrogen after biochemical treatment. Treatment effect of anaerobic ammonium oxidation （anammox） process on the mixture of the leachate and its biochemical effluent was investigated. The results show that the average removal efficiencies of ammonium, nitric nitrogen and total nitrogen are 87.51%, 74.95% and 79.59%, respectively, corresponding to the average ratio of removed nitric nitrogen to ammonium, i.e. 1.14 during the steady phase of anammox activity. The mean removal efficiency of COD is only 24.01% during the experimental period. Thc,dcmand of total phosphorous for the anammox process is unobvious. Especially, the alkalinity and pH value of the effluent are close to those of the inftuent during the steady phase of anammox activity. In addition, it is demonstrated that the status of the anammox bioreactor can be indicated by the alkalinity and pH value during the course of the experiment. The anammox bioreactor has shown potential for nitrogen removal in the leachate mixture. However, COD and total phosphorous in the leachate mixture need further treatment for removal efficiencies of COD and total phosphorous are not good in the anammox bioreactor.
基金Project (2009ZX07315-002-01) supported by Water Pollution Control and Management of Major Special Science and Technology
文摘Full scale experimental study on nitrogen removal for low-carbon wastewater was conducted in reversed A2/O process in Jiguanshi waste water treatment plant in Chongqing,in order to aid the operation and maintenance of similar WWTP. When the proposed measures,such as using 0.1% (volume fraction of wastewater) landfill leachate,shortening HRT by 2/3 in the primary sedimentation tank and controlling DO at 0.5 mg/L in the 3rd section of aerobic zone,are applied,15% of the carbon source can be complemented,the favorable property of activated sludge is achieved,and the nitrogen removal effect is significantly improved. The effluent NH3-N is 2 mg/L and the removal rate is 90%. The effluent TN is 17 mg/L and the removal rate is 54%. The up-to-standard discharge of the effluent is achieved. And after the optimization,the unit electricity consumption also reaches 0.21 kW/h and saves 20%.
基金Projects(42174170,41874145,72088101)supported by the National Natural Science Foundation of ChinaProject(CX20200228)supported by the Hunan Provincial Innovation Foundation for Postgraduate,China。
文摘Landfill leaks pose a serious threat to environmental health,risking the contamination of both groundwater and soil resources.Accurate investigation of these sites is essential for implementing effective prevention and control measures.The self-potential(SP)stands out for its sensitivity to contamination plumes,offering a solution for monitoring and detecting the movement and seepage of subsurface pollutants.However,traditional SP inversion techniques heavily rely on precise subsurface resistivity information.In this study,we propose the Attention U-Net deep learning network for rapid SP inversion.By incorporating an attention mechanism,this algorithm effectively learns the relationship between array-style SP data and the location and extent of subsurface contaminated sources.We designed a synthetic landfill model with a heterogeneous resistivity structure to assess the performance of Attention U-Net deep learning network.Additionally,we conducted further validation using a laboratory model to assess its practical applicability.The results demonstrate that the algorithm is not solely dependent on resistivity information,enabling effective locating of the source distribution,even in models with intricate subsurface structures.Our work provides a promising tool for SP data processing,enhancing the applicability of this method in the field of near-subsurface environmental monitoring.
