A pilot-scale modified carbon source division anaerobic anoxic oxic(AAO) process with pre-concentration of returned activated sludge(RAS) was proposed in this study for the enhanced biological nutrient removal(BNR) of...A pilot-scale modified carbon source division anaerobic anoxic oxic(AAO) process with pre-concentration of returned activated sludge(RAS) was proposed in this study for the enhanced biological nutrient removal(BNR) of municipal wastewater with limited carbon source. The influent carbon source was fed in step while a novel RAS pre-concentration tank was adopted to improve BNR efficiency, and the effects of an influent carbon source distribution ratio and a RAS pre-concentration ratio were investigated. The results show that the removal efficiency of TN is mainly influenced by the carbon source distribution ratio while the TP removal relies on the RAS pre-concentration ratio. The optimum carbon source distribution ratio and RAS pre-concentration ratio are 60% and 50%, respectively, with an inner recycling ratio of 100% under the optimum steady operation of pilot test, reaching an average effluent TN concentration of 9.8 mg·L-1with a removal efficiency of 63% and an average TP removal efficiency of 94%. The mechanism of nutrient removal is discussed and the kinetics is analyzed. The results reveal that the optimal carbon source distribution ratio provides sufficient denitrifying carbon source to each anoxic phase, reducing nitrate accumulation while the RAS pre-concentration ratio improves the condition of anaerobic zone to ensure the phosphorus release due to less nitrate in the returned sludge. Therefore, nitrifying bacteria, denitrifying bacteria and phosphorus accumulation organisms play an important role under the optimum condition, enhancing the performance of nutrient removal in this test.展开更多
A kind of conductive and heating unit, which can reach a high surface electroheat temperature at a low voltage, was developed in view of the traditional electroheat coating which has a low surface electroheat temperat...A kind of conductive and heating unit, which can reach a high surface electroheat temperature at a low voltage, was developed in view of the traditional electroheat coating which has a low surface electroheat temperature and an insufficient heat resistance of its binder. The coating molded electroheat carbon film(CMECF) was prepared by carbonizing the coating which was prepared by adding modified resin into flake graphite and carbon fiber, coating molded onto the surface of the heat resisting matrix after dried, while the hot pressing molded electroheat thick carbon film(HPMETCF) was prepared by carbonizing the bodies whose powders were hot pressing molded directly. The surface and inner microstructure of the carbon film was characterized and analyzed by SEM and DSC/TG, while electroheat property was tested by voltage-current volume resistivity tester and electrical parameter tester. The results show that, close-packed carbon network configuration is formed within the composite electroheat carbon film which yields a volume resistivity of 0.5×10 -210.0×10 -2Ω·cm at room temperature. The electroheat carbon film after anti-oxidizable treatment reaches a higher surface electroheat temperature than that of the existing electroheat coatings at a low voltage, and has excellent electroheat property, high thermal efficiency as well as stable physicochemical property. It is found that, at room temperature(19±2℃) and 22V for 5min, the surface electroheat temperature of the self-produced CMECF (m_ filler/m_ resin=1.8/1) reaches 112℃ while HPMETCF (m_ filler/m_ resin=3.6/1) reaches 265℃.展开更多
Underground engineering,including shield tunnel construction,is a significant contributor to carbon dioxide emissions in infrastructure engineering projects.To better predict and control the carbon emissions associate...Underground engineering,including shield tunnel construction,is a significant contributor to carbon dioxide emissions in infrastructure engineering projects.To better predict and control the carbon emissions associated with shield tunnel construction,this paper presents a novel calculation method:the modified process analysis method based on inputoutput and process analysis methods.To evaluate the effectiveness of the proposed method,a specific shield tunnel construction project was selected as a case study.The modified process analysis method was used to analyze the various factors that influence carbon emissions during the project’s construction phase.In addition,a neural network approach was applied to validate the accuracy of the calculation using the LSTM and BP neural network.The results demonstrate that the proposed method not only combines the strengths of traditional methods but also offers high accuracy and acceptable error rates.Based on these findings,several measures to reduce carbon emissions during shield tunnel construction are suggested,providing valuable insights for reducing CO_(2) emissions associated with infrastructure engineering projects.This study highlights the importance of adopting innovative approaches to reduce carbon emissions and promotes the implementation of sustainable practices in the construction industry.Through the use of advanced analytical methods,such as the proposed modified process analysis method,we can effectively mitigate the environmental impact of construction activities and make significant contributions to the global effort to combat climate change.展开更多
基金Supported by the Major Science and Technology Program for Water Pollution Contro and Treatment-Crucial Technology Research and Engineering Sample Subject on Municipa Wastewater Treatment Process Updated to Higher Drainage Standard(2008ZX07317-02)Wuhan Water Pollution Control and the Water Environment Administer Technology and Synthetic Sample Project in Cities and Towns(2008ZX07317)
文摘A pilot-scale modified carbon source division anaerobic anoxic oxic(AAO) process with pre-concentration of returned activated sludge(RAS) was proposed in this study for the enhanced biological nutrient removal(BNR) of municipal wastewater with limited carbon source. The influent carbon source was fed in step while a novel RAS pre-concentration tank was adopted to improve BNR efficiency, and the effects of an influent carbon source distribution ratio and a RAS pre-concentration ratio were investigated. The results show that the removal efficiency of TN is mainly influenced by the carbon source distribution ratio while the TP removal relies on the RAS pre-concentration ratio. The optimum carbon source distribution ratio and RAS pre-concentration ratio are 60% and 50%, respectively, with an inner recycling ratio of 100% under the optimum steady operation of pilot test, reaching an average effluent TN concentration of 9.8 mg·L-1with a removal efficiency of 63% and an average TP removal efficiency of 94%. The mechanism of nutrient removal is discussed and the kinetics is analyzed. The results reveal that the optimal carbon source distribution ratio provides sufficient denitrifying carbon source to each anoxic phase, reducing nitrate accumulation while the RAS pre-concentration ratio improves the condition of anaerobic zone to ensure the phosphorus release due to less nitrate in the returned sludge. Therefore, nitrifying bacteria, denitrifying bacteria and phosphorus accumulation organisms play an important role under the optimum condition, enhancing the performance of nutrient removal in this test.
文摘A kind of conductive and heating unit, which can reach a high surface electroheat temperature at a low voltage, was developed in view of the traditional electroheat coating which has a low surface electroheat temperature and an insufficient heat resistance of its binder. The coating molded electroheat carbon film(CMECF) was prepared by carbonizing the coating which was prepared by adding modified resin into flake graphite and carbon fiber, coating molded onto the surface of the heat resisting matrix after dried, while the hot pressing molded electroheat thick carbon film(HPMETCF) was prepared by carbonizing the bodies whose powders were hot pressing molded directly. The surface and inner microstructure of the carbon film was characterized and analyzed by SEM and DSC/TG, while electroheat property was tested by voltage-current volume resistivity tester and electrical parameter tester. The results show that, close-packed carbon network configuration is formed within the composite electroheat carbon film which yields a volume resistivity of 0.5×10 -210.0×10 -2Ω·cm at room temperature. The electroheat carbon film after anti-oxidizable treatment reaches a higher surface electroheat temperature than that of the existing electroheat coatings at a low voltage, and has excellent electroheat property, high thermal efficiency as well as stable physicochemical property. It is found that, at room temperature(19±2℃) and 22V for 5min, the surface electroheat temperature of the self-produced CMECF (m_ filler/m_ resin=1.8/1) reaches 112℃ while HPMETCF (m_ filler/m_ resin=3.6/1) reaches 265℃.
基金supported by the National Natural Science Foundation of China(Grant No.52079128)Anhui province university discipline(professional)top talents academic funding project,project number:gxbjZD2022085.
文摘Underground engineering,including shield tunnel construction,is a significant contributor to carbon dioxide emissions in infrastructure engineering projects.To better predict and control the carbon emissions associated with shield tunnel construction,this paper presents a novel calculation method:the modified process analysis method based on inputoutput and process analysis methods.To evaluate the effectiveness of the proposed method,a specific shield tunnel construction project was selected as a case study.The modified process analysis method was used to analyze the various factors that influence carbon emissions during the project’s construction phase.In addition,a neural network approach was applied to validate the accuracy of the calculation using the LSTM and BP neural network.The results demonstrate that the proposed method not only combines the strengths of traditional methods but also offers high accuracy and acceptable error rates.Based on these findings,several measures to reduce carbon emissions during shield tunnel construction are suggested,providing valuable insights for reducing CO_(2) emissions associated with infrastructure engineering projects.This study highlights the importance of adopting innovative approaches to reduce carbon emissions and promotes the implementation of sustainable practices in the construction industry.Through the use of advanced analytical methods,such as the proposed modified process analysis method,we can effectively mitigate the environmental impact of construction activities and make significant contributions to the global effort to combat climate change.
