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
Detection of floating garbage in inland rivers is crucial for water environmental protection,as it effectively reduces ecological damage and ensures the safety of water resources.To address the inefficiency of traditi...Detection of floating garbage in inland rivers is crucial for water environmental protection,as it effectively reduces ecological damage and ensures the safety of water resources.To address the inefficiency of traditional cleanup methods and the challenges in detecting small targets,an improved YOLOv5 object detection model was proposed in this study.In order to enhance the model’s sensitivity to small targets and mitigate the impact of redundant information on detection performance,a bi-level routing attention mechanism was introduced and embedded into the backbone network.Additionally,a multi-scale detection head was incorporated into the model,allowing for more comprehensive coverage of floating garbage of various sizes through multi-scale feature extraction and detection.The Focal-EIoU loss function was also employed to optimize the model parameters,improving localization accuracy.Experimental results on the publicly available FloW_Img dataset demonstrated that the improved YOLOv5 model outperforms the original YOLOv5 model in terms of precision and recall,achieving a mAP(mean average precision)of 86.12%,with significant improvements and faster convergence.展开更多
Construction wastes were selected as the adsorbents and static and dynamic adsorption batch experiments were carried out to investigate the adsorption of Pb to construction wastes with different particle size gradatio...Construction wastes were selected as the adsorbents and static and dynamic adsorption batch experiments were carried out to investigate the adsorption of Pb to construction wastes with different particle size gradations in the simulated stormwater runoff system.The experimental results show that the pseudo-second-order kinetics model can better characterize the adsorption process of Pb than the pseudo-first-order kinetics model.The adsorption equilibrium data can be well fitted by the Freundlich isotherm model. The construction wastes with different tested size gradations can greatly remove Pb from stormwater runoff and their average removal rate can reach up to 99%.The construction wastes with narrow size distribution can better remove Pb but with worse permeability than those with wide size distribution. The particle size gradation of construction wastes greatly influences the equilibrium time rate and the capacity of Pb adsorption.The equilibrium adsorption rate and capacity are 18.1 μg/min and 5.5 μg/g respectively for the construction wastes with the size of 2.36 to 4.75 mm which are the greatest among the different size gradations.The present study provides a scientific basis for effectively controlling Pb pollution from stormwater runoff and the construction wastes resource utilization.展开更多
A three-dimensional numerical model verified by previous experimental data is developed to simulate the fluidized bed gasification of refuse derived fuel （RDF）. The CaO dechlorination model obtained by the thermal g...A three-dimensional numerical model verified by previous experimental data is developed to simulate the fluidized bed gasification of refuse derived fuel （RDF）. The CaO dechlorination model obtained by the thermal gravity analysis （TGA） is coupled to investigate the process of CaO dechlorination. An Eulerian-Eulerian method is adopted to simulate the gas-solid flow and self-developed chemical reaction modules are used to simulate chemical reactions. Flow patterns, gasification results and dechlorination efficiency are obtained by numerical simulation. Meanwhile, simulations are performed to evaluate the effects of Ca/Cl molar ratio and temperature on dechlorination efficiency. The simulation results show that the presence of bubbles in the gasifier lowers the CaO dechlorination efficiency. Increasing the Ca/Cl molar ratio can enhance the dechlorination efficiency. However, with the temperature increasing, the dechlorination efficiency increases initially and then decreases. The optimal Ca/Cl molar ratio is in the range of 3. 0 to 3. 5 and the optimal temperature is 923K.展开更多
The extraction behavior of heavy metals from municipal waste incineration （MWI） fly ash was investigated systematically. The extraction process includes two steps, namely, fly ash was firstly washed with water, and ...The extraction behavior of heavy metals from municipal waste incineration （MWI） fly ash was investigated systematically. The extraction process includes two steps, namely, fly ash was firstly washed with water, and then subjected to hydrochloric acid leaching. The main parameters for water washing process were tested, and under the optimal conditions, about 86% Na, 70% K and 12% Ca were removed from fly ash, respectively. Hydrochloric acid was used for the extraction of valuable elements from the water-washed fly ash, and the optimal extraction was achieved for each heavy metal as follows： 86% for Pb, 98% for Zn, 82% for Fe, 96% for Cd, 62% for Cu, 80% for Al, respectively. And the main compositions of the finally obtained solid residue are Ca2PbO4, CaSi2Os, PbsSiO7, Ca3A12Si3012 and SiO2.展开更多
Leachate from a sanitary landfill site in Chengdu, China is treated using a hybrid-UASB reactor at pilot scale. H2S, resulting from the anaerobic bioconversion process of sulfate-reducing bacteria（SRB）, inhibits the...Leachate from a sanitary landfill site in Chengdu, China is treated using a hybrid-UASB reactor at pilot scale. H2S, resulting from the anaerobic bioconversion process of sulfate-reducing bacteria（SRB）, inhibits the growth and activity of methane-producing bacteria（MPB）and poses serious problems of pollution, so FeCl3is used for H2S removal. The results show that the system performs well in the treatment process. COD removal generally increases with the increase in the organic loading rate（OLR）, while the sulfate removal decreases slowly. As the OLR is higher than 7 kgCOD/（m3·d）, both COD and sulfate removal tend to be stable. When the reactor is operated at the design load of 9 kgCOD/（m3·d）, COD and sulfate removal remain about 79% and 91%, respectively. At the same time, the percentage of COD removed by SRB（CODSRB）also decreases from 8.9% to 4.0%. With FeCl3 addition, COD removal increases to 83%, while sulfate removal and CODSRBfurther decrease to 89% and 1.89%, respectively. According to the mass balance, nearly 82% of the sulfur is prevented from converting into H2S. Moreover, when the FeCl3 dosage is more than 1.6 g/L leachate, H2S can be removed totally from the biogas. Therefore, the application of FeCl3 for H2S removal in leachate treatment using the UASB reactor is very suitable and viable.展开更多
In order to investigate the influence of secondary classification mode on waste generation features, this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Vi...In order to investigate the influence of secondary classification mode on waste generation features, this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Village of Xiqing District into 3 groups： compostable materials, recyclable materials and toxics on the basis of the constructed secondary classification mode of domestic waste. The study focused on waste generation strength and classification features, compared the waste generation features between rural and urban residents, and analyzed the re- lation between waste generation strength and economic and cultural factors. The re- sults indicated that the average generation speed of urban domestic waste was 423.08 g/（d.capita）, and that of rural domestic waste was 629.89 g/（d.capita）, there was significant difference between rural and urban compost generation strength （P= 0.00002）, while the generation strength of recyclable materials and toxics between rural and urban areas had no significant difference （P=0.471 and P=0.099, respec- tively）. Secondary classification mode is an effective source classification mode for domestic wastes and has positive effects on waste reduction and treatment.展开更多
The rapidly increasing demand for energy in China leads to the construction of new power plants all over the country. Coal, as the main fuel resource of those power plants, results in increasing problems with the disp...The rapidly increasing demand for energy in China leads to the construction of new power plants all over the country. Coal, as the main fuel resource of those power plants, results in increasing problems with the disposal of solid residues from combustion and off gas cleaning. This investigation describes chances for the utilization of fly ash from coal-fired power plants in China. After briefly comparing the situation in China and Germany, the status of aluminum recycling from fly ash and the ad- vantages for using fly ash in concrete products are introduced. Chemical and physical analyses of Chinese fly ash samples, e.g., X-ray diffraction (XRD), ICP (Inductive Coupled Plasma) and particle size analysis, water requirement, etc. are presented. Rea- sonable amounts of aluminum were detected in the samples under investigation, but for recovery only sophisticated procedures are available up to now. Therefore, simpler techniques are suggested for the first steps in the utilization of Chinese fly ash.展开更多
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.
文摘Detection of floating garbage in inland rivers is crucial for water environmental protection,as it effectively reduces ecological damage and ensures the safety of water resources.To address the inefficiency of traditional cleanup methods and the challenges in detecting small targets,an improved YOLOv5 object detection model was proposed in this study.In order to enhance the model’s sensitivity to small targets and mitigate the impact of redundant information on detection performance,a bi-level routing attention mechanism was introduced and embedded into the backbone network.Additionally,a multi-scale detection head was incorporated into the model,allowing for more comprehensive coverage of floating garbage of various sizes through multi-scale feature extraction and detection.The Focal-EIoU loss function was also employed to optimize the model parameters,improving localization accuracy.Experimental results on the publicly available FloW_Img dataset demonstrated that the improved YOLOv5 model outperforms the original YOLOv5 model in terms of precision and recall,achieving a mAP(mean average precision)of 86.12%,with significant improvements and faster convergence.
基金The National Natural Science Foundation of China(No.51208022)the National Science and Technology Major Project of China(No.2011ZX07301-004-01)
文摘Construction wastes were selected as the adsorbents and static and dynamic adsorption batch experiments were carried out to investigate the adsorption of Pb to construction wastes with different particle size gradations in the simulated stormwater runoff system.The experimental results show that the pseudo-second-order kinetics model can better characterize the adsorption process of Pb than the pseudo-first-order kinetics model.The adsorption equilibrium data can be well fitted by the Freundlich isotherm model. The construction wastes with different tested size gradations can greatly remove Pb from stormwater runoff and their average removal rate can reach up to 99%.The construction wastes with narrow size distribution can better remove Pb but with worse permeability than those with wide size distribution. The particle size gradation of construction wastes greatly influences the equilibrium time rate and the capacity of Pb adsorption.The equilibrium adsorption rate and capacity are 18.1 μg/min and 5.5 μg/g respectively for the construction wastes with the size of 2.36 to 4.75 mm which are the greatest among the different size gradations.The present study provides a scientific basis for effectively controlling Pb pollution from stormwater runoff and the construction wastes resource utilization.
基金The National Natural Science Foundation of China(No.51476032)
文摘A three-dimensional numerical model verified by previous experimental data is developed to simulate the fluidized bed gasification of refuse derived fuel （RDF）. The CaO dechlorination model obtained by the thermal gravity analysis （TGA） is coupled to investigate the process of CaO dechlorination. An Eulerian-Eulerian method is adopted to simulate the gas-solid flow and self-developed chemical reaction modules are used to simulate chemical reactions. Flow patterns, gasification results and dechlorination efficiency are obtained by numerical simulation. Meanwhile, simulations are performed to evaluate the effects of Ca/Cl molar ratio and temperature on dechlorination efficiency. The simulation results show that the presence of bubbles in the gasifier lowers the CaO dechlorination efficiency. Increasing the Ca/Cl molar ratio can enhance the dechlorination efficiency. However, with the temperature increasing, the dechlorination efficiency increases initially and then decreases. The optimal Ca/Cl molar ratio is in the range of 3. 0 to 3. 5 and the optimal temperature is 923K.
文摘The extraction behavior of heavy metals from municipal waste incineration （MWI） fly ash was investigated systematically. The extraction process includes two steps, namely, fly ash was firstly washed with water, and then subjected to hydrochloric acid leaching. The main parameters for water washing process were tested, and under the optimal conditions, about 86% Na, 70% K and 12% Ca were removed from fly ash, respectively. Hydrochloric acid was used for the extraction of valuable elements from the water-washed fly ash, and the optimal extraction was achieved for each heavy metal as follows： 86% for Pb, 98% for Zn, 82% for Fe, 96% for Cd, 62% for Cu, 80% for Al, respectively. And the main compositions of the finally obtained solid residue are Ca2PbO4, CaSi2Os, PbsSiO7, Ca3A12Si3012 and SiO2.
文摘Leachate from a sanitary landfill site in Chengdu, China is treated using a hybrid-UASB reactor at pilot scale. H2S, resulting from the anaerobic bioconversion process of sulfate-reducing bacteria（SRB）, inhibits the growth and activity of methane-producing bacteria（MPB）and poses serious problems of pollution, so FeCl3is used for H2S removal. The results show that the system performs well in the treatment process. COD removal generally increases with the increase in the organic loading rate（OLR）, while the sulfate removal decreases slowly. As the OLR is higher than 7 kgCOD/（m3·d）, both COD and sulfate removal tend to be stable. When the reactor is operated at the design load of 9 kgCOD/（m3·d）, COD and sulfate removal remain about 79% and 91%, respectively. At the same time, the percentage of COD removed by SRB（CODSRB）also decreases from 8.9% to 4.0%. With FeCl3 addition, COD removal increases to 83%, while sulfate removal and CODSRBfurther decrease to 89% and 1.89%, respectively. According to the mass balance, nearly 82% of the sulfur is prevented from converting into H2S. Moreover, when the FeCl3 dosage is more than 1.6 g/L leachate, H2S can be removed totally from the biogas. Therefore, the application of FeCl3 for H2S removal in leachate treatment using the UASB reactor is very suitable and viable.
基金Supported by Agricultural Scientific and Technological Achievement Transformation and Popularization Project of Tianjin(201003010)~~
文摘In order to investigate the influence of secondary classification mode on waste generation features, this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Village of Xiqing District into 3 groups： compostable materials, recyclable materials and toxics on the basis of the constructed secondary classification mode of domestic waste. The study focused on waste generation strength and classification features, compared the waste generation features between rural and urban residents, and analyzed the re- lation between waste generation strength and economic and cultural factors. The re- sults indicated that the average generation speed of urban domestic waste was 423.08 g/（d.capita）, and that of rural domestic waste was 629.89 g/（d.capita）, there was significant difference between rural and urban compost generation strength （P= 0.00002）, while the generation strength of recyclable materials and toxics between rural and urban areas had no significant difference （P=0.471 and P=0.099, respec- tively）. Secondary classification mode is an effective source classification mode for domestic wastes and has positive effects on waste reduction and treatment.
文摘The rapidly increasing demand for energy in China leads to the construction of new power plants all over the country. Coal, as the main fuel resource of those power plants, results in increasing problems with the disposal of solid residues from combustion and off gas cleaning. This investigation describes chances for the utilization of fly ash from coal-fired power plants in China. After briefly comparing the situation in China and Germany, the status of aluminum recycling from fly ash and the ad- vantages for using fly ash in concrete products are introduced. Chemical and physical analyses of Chinese fly ash samples, e.g., X-ray diffraction (XRD), ICP (Inductive Coupled Plasma) and particle size analysis, water requirement, etc. are presented. Rea- sonable amounts of aluminum were detected in the samples under investigation, but for recovery only sophisticated procedures are available up to now. Therefore, simpler techniques are suggested for the first steps in the utilization of Chinese fly ash.
