By considering the flow control of urban sewer networks to minimize the electricity consumption of pumping stations, a decomposition-coordination strategy for energy savings based on network community division is deve...By considering the flow control of urban sewer networks to minimize the electricity consumption of pumping stations, a decomposition-coordination strategy for energy savings based on network community division is developed in this paper. A mathematical model characterizing the steady-state flow of urban sewer networks is first constructed, consisting of a set of algebraic equations with the structure transportation capacities captured as constraints. Since the sewer networks have no apparent natural hierarchical structure in general, it is very difficult to identify the clustered groups. A fast network division approach through calculating the betweenness of each edge is successfully applied to identify the groups and a sewer network with arbitrary configuration could be then decomposed into subnetworks. By integrating the coupling constraints of the subnetworks, the original problem is separated into N optimization subproblems in accordance with the network decomposition. Each subproblem is solved locally and the solutions to the subproblems are coordinated to form an appropriate global solution. Finally, an application to a specified large-scale sewer network is also investigated to demonstrate the validity of the proposed algorithm.展开更多
The performance of sewer network is associated with both clean water infiltration and in-sewer pollutant degradation.Quantifying their contributions in large-scale sewer network remains challenging due to the infeasib...The performance of sewer network is associated with both clean water infiltration and in-sewer pollutant degradation.Quantifying their contributions in large-scale sewer network remains challenging due to the infeasibility of numerous on-site measurements of water flows and water quality concentrations in the whole system.This study developed a physically inverse problem approach to address this challenge,which was tested in an actual sewer network system(25.66 km^(2))with gridding-based in-sewer flow rate and water quality measurements.Bayesian optimization framework was integrated into sewer hydrodynamic and water quality models to inversely estimate source parameters including source flow rates and source discharge concentrations.Employing simulated annealing algorithm can demonstrate 20.6%-54.2% higher accuracy compared with the other methods,due to its progressive instead of fast and steep convergence toward the true solutions.With the developed approach,the infiltrated clean water infiltration and mass loss of chemical oxygen demand(COD)within the sewer network were quantified synchronously.Further,the condition of sewer structural defects was assessed,and a reference value for allowable in-sewer COD degradation was also presented,which was 4%-5%COD mass per hour of sewage hydraulic retention.Therefore,this methodology can provide cost-effective solution for comprehensive assessment of sewer network conditions.展开更多
Chinese authorities and the public have largely ignored sewer networks; however, various problems are emerging nationwide with the increase construction of new sewers. The current state of sewer network construction, ...Chinese authorities and the public have largely ignored sewer networks; however, various problems are emerging nationwide with the increase construction of new sewers. The current state of sewer network construction, administration, and maintenance in China is comprehensively reviewed in this study. Serving about 444 million people, 511,200 km of sewer lines are located in urban areas. In 2014,$7 billion was invested in sewer network construction. However, both the sewer pervasion rate and the per capita sewer length were significantly lower than those in developed countries. Sewer administrative agencies in local governments are uncoordinated. Laws, regulations, and standards are incomplete, and some practices are unscientific. The future situation of sewer maintenance is extremely grim because sewer corrosion control measures have not been launched. Moreover, inspection and rehabilitation chiefly rely on traditional approaches. In contrast, the overall market share of innovative technologies is very low owing to high cost, funds shortage, and technical limitations. Approaches such-as liner inversion cured-in-place pipe, pull-in ultraviolet light cured liners, and spiral wound lining are applied mostly in economically developed regions. According to status and problem analyses, China＇s top priority will be to conduct aggressive maintenance work in sewer networks in the future. New technical route, corrosion control - periodic visualized inspection - trenchless rehabilitation, could be the best option for future sewer maintenance in China. Instmctions and opportunities for applying this technical route are discussed in detail in this study. Finally.additional factors in the development of sewer networks in China are suggested.展开更多
Flow in an urban drainage network is usually unsteady with backwater near junctions. The routing of hydrographs through a network is an important aspect of the design and analysis of urban drainage networks. Various ...Flow in an urban drainage network is usually unsteady with backwater near junctions. The routing of hydrographs through a network is an important aspect of the design and analysis of urban drainage networks. Various numerical methods to analyze flow in urban drainage networks were compared and a new hybrid interpolation scheme was developed which combined time-line reachback interpolation, implicit interpolation and space-line interpolation. Numerical simulations show that the improved method more accurately models flows in urban drainage networks.展开更多
Sewer networks play a vital role in sewage collection and transportation,and they are being rapidly expanded.However,the microbial processes occurring within these networks have emerged as significant contributors to ...Sewer networks play a vital role in sewage collection and transportation,and they are being rapidly expanded.However,the microbial processes occurring within these networks have emerged as significant contributors to greenhouse gas(GHG)emissions.Compared to that from other sectors,our understanding of the magnitude of GHG emissions from sewer networks is currently limited.In this study,we conducted a GHG emission assessment in an independent sewer network located in Beijing,China.The findings revealed annual emissions of 62.3 kg CH_(4) and 0.753 kg N20.CH_(4) emerged as the primary GHG emitted from sewers,accounting for 87.4%of the total GHG emissions.Interestingly,compared with main pipes,branch pipes were responsible for a larger share of GHG emissions,contributing to 76.7%of the total.A GHG emission factor of 0.26 kg CO_(2)-eq/(m:yr)was established to quantify sewer GHG emissions.By examining the isotopic signatures of CO_(2)/CH_(4) pairs,it was determined that CH_(4) production in sewers primarily occurred through acetate fermentation.Additionally,the structure of sewer pipes had a significant impact on GHG levels.This study offers valuable insights into the overall GHG emissions associated with sewer networks and sheds ight on themechanismsdriving theseemissions.展开更多
针对污水收集系统中因泵站流量在线监测数据缺失而导致的管网运行监管难题,提出了一种基于泵站运行状态高效监管降雨引发的入流入渗(rainfall-induced inflow and infiltration,简称RDII)的技术。该技术依次从水泵运行时长、晴雨天液位...针对污水收集系统中因泵站流量在线监测数据缺失而导致的管网运行监管难题,提出了一种基于泵站运行状态高效监管降雨引发的入流入渗(rainfall-induced inflow and infiltration,简称RDII)的技术。该技术依次从水泵运行时长、晴雨天液位波动幅度、峰值液位及液位峰谷比4个方面,通过各指标的波动幅度和相关性分析,综合诊断了各泵站运行状态以及RDII严重程度。通过分析泵站在降雨事件中的运行反应模式,能够精确识别并定位问题源头的关键区域,从而有效缩小诊断范围并提升诊断效率。研究结果表明,在考察区域内,上游泵站P1的RDII问题最为严重,且其末端泵站P4在雨天运行时负荷显著增加,两者具有较强关联性。具体而言,在雨天条件下,泵站P1的水泵运行时长相较于晴天大幅增加,最大增幅达到了77.94%;同时,雨天时开泵状态下的液位比晴天平均上升了0.76 m,峰值液位更是高达3.01 m,且在关泵状态下伴随着极端的液位峰谷比,最高值达到了4.32。在泵站P1的服务区域内增设管网流量在线监测设备,结果表明,泵站P1收集区域的管网RDII比例在2.22%~85.12%大幅波动,直接导致了下游泵站P4在雨天运行时负荷的显著升高。以上研究结果不仅为同类污水系统的RDII问题提供了科学的诊断方法,还可为优化诊断流程、提升成本效益比提供可行的解决方案。展开更多
基金the National Natural Science Foundation of China (No.60674041, 60504026)the National High Technology Project(No.2006AA04Z173).
文摘By considering the flow control of urban sewer networks to minimize the electricity consumption of pumping stations, a decomposition-coordination strategy for energy savings based on network community division is developed in this paper. A mathematical model characterizing the steady-state flow of urban sewer networks is first constructed, consisting of a set of algebraic equations with the structure transportation capacities captured as constraints. Since the sewer networks have no apparent natural hierarchical structure in general, it is very difficult to identify the clustered groups. A fast network division approach through calculating the betweenness of each edge is successfully applied to identify the groups and a sewer network with arbitrary configuration could be then decomposed into subnetworks. By integrating the coupling constraints of the subnetworks, the original problem is separated into N optimization subproblems in accordance with the network decomposition. Each subproblem is solved locally and the solutions to the subproblems are coordinated to form an appropriate global solution. Finally, an application to a specified large-scale sewer network is also investigated to demonstrate the validity of the proposed algorithm.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFC3200703)the Research Program of China Three Gorges Corporation(Grant No.202403181)the National Natural Science Foundation of China(Grant No.52170103).
文摘The performance of sewer network is associated with both clean water infiltration and in-sewer pollutant degradation.Quantifying their contributions in large-scale sewer network remains challenging due to the infeasibility of numerous on-site measurements of water flows and water quality concentrations in the whole system.This study developed a physically inverse problem approach to address this challenge,which was tested in an actual sewer network system(25.66 km^(2))with gridding-based in-sewer flow rate and water quality measurements.Bayesian optimization framework was integrated into sewer hydrodynamic and water quality models to inversely estimate source parameters including source flow rates and source discharge concentrations.Employing simulated annealing algorithm can demonstrate 20.6%-54.2% higher accuracy compared with the other methods,due to its progressive instead of fast and steep convergence toward the true solutions.With the developed approach,the infiltrated clean water infiltration and mass loss of chemical oxygen demand(COD)within the sewer network were quantified synchronously.Further,the condition of sewer structural defects was assessed,and a reference value for allowable in-sewer COD degradation was also presented,which was 4%-5%COD mass per hour of sewage hydraulic retention.Therefore,this methodology can provide cost-effective solution for comprehensive assessment of sewer network conditions.
文摘Chinese authorities and the public have largely ignored sewer networks; however, various problems are emerging nationwide with the increase construction of new sewers. The current state of sewer network construction, administration, and maintenance in China is comprehensively reviewed in this study. Serving about 444 million people, 511,200 km of sewer lines are located in urban areas. In 2014,$7 billion was invested in sewer network construction. However, both the sewer pervasion rate and the per capita sewer length were significantly lower than those in developed countries. Sewer administrative agencies in local governments are uncoordinated. Laws, regulations, and standards are incomplete, and some practices are unscientific. The future situation of sewer maintenance is extremely grim because sewer corrosion control measures have not been launched. Moreover, inspection and rehabilitation chiefly rely on traditional approaches. In contrast, the overall market share of innovative technologies is very low owing to high cost, funds shortage, and technical limitations. Approaches such-as liner inversion cured-in-place pipe, pull-in ultraviolet light cured liners, and spiral wound lining are applied mostly in economically developed regions. According to status and problem analyses, China＇s top priority will be to conduct aggressive maintenance work in sewer networks in the future. New technical route, corrosion control - periodic visualized inspection - trenchless rehabilitation, could be the best option for future sewer maintenance in China. Instmctions and opportunities for applying this technical route are discussed in detail in this study. Finally.additional factors in the development of sewer networks in China are suggested.
文摘Flow in an urban drainage network is usually unsteady with backwater near junctions. The routing of hydrographs through a network is an important aspect of the design and analysis of urban drainage networks. Various numerical methods to analyze flow in urban drainage networks were compared and a new hybrid interpolation scheme was developed which combined time-line reachback interpolation, implicit interpolation and space-line interpolation. Numerical simulations show that the improved method more accurately models flows in urban drainage networks.
基金financially supported by the National Key Research and Development Program of China(No.2022YFC3203202-3)the Shenzhen Science and Technology Innovation Commission(No.KCXFZ20211020163556020).
文摘Sewer networks play a vital role in sewage collection and transportation,and they are being rapidly expanded.However,the microbial processes occurring within these networks have emerged as significant contributors to greenhouse gas(GHG)emissions.Compared to that from other sectors,our understanding of the magnitude of GHG emissions from sewer networks is currently limited.In this study,we conducted a GHG emission assessment in an independent sewer network located in Beijing,China.The findings revealed annual emissions of 62.3 kg CH_(4) and 0.753 kg N20.CH_(4) emerged as the primary GHG emitted from sewers,accounting for 87.4%of the total GHG emissions.Interestingly,compared with main pipes,branch pipes were responsible for a larger share of GHG emissions,contributing to 76.7%of the total.A GHG emission factor of 0.26 kg CO_(2)-eq/(m:yr)was established to quantify sewer GHG emissions.By examining the isotopic signatures of CO_(2)/CH_(4) pairs,it was determined that CH_(4) production in sewers primarily occurred through acetate fermentation.Additionally,the structure of sewer pipes had a significant impact on GHG levels.This study offers valuable insights into the overall GHG emissions associated with sewer networks and sheds ight on themechanismsdriving theseemissions.
