The City of Calgary’s Nose Creek Sanitary Sewer Trunk Phase B project has been constructed over several years to accommodate future population growth and open more developable lands in northern Calgary.The project wa...The City of Calgary’s Nose Creek Sanitary Sewer Trunk Phase B project has been constructed over several years to accommodate future population growth and open more developable lands in northern Calgary.The project was divided into three phases,Phase A,B,and C,with each phase delivered by a separate consultant.Phase A was the downstream section of this project and was undertaken by Stantec Consulting.Phase B was the upstream section designed by CH2MHILL(now Jacobs)and further divided into different contracts(1 through 5).Phase C was a separate sewer called the Saddleridge Trunk sewer and this was designed by Associated Engineering.This paper covers Phase B,Contract 4,which had several unique challenges and included many innovative design and procurement solutions.One procurement strategy included a two-phase qualification package,with the initial phase to select a tunnelling contractor with the experience to deliver technical installations under rail and creeks,and the second phase,a RFP(request for proposal),to select a general contractor,with broader experience in open-cut and stormwater drainage,which were other aspects included within the project.This approach ensured that The City had the most qualified team available to complete the project.Technical challenges discussed in this paper include an oblique CPKC(Canadian Pacific Kansas City)rail and Nose Creek crossing that required independent review,and CFD(computational fluid dynamics)and hydrogen sulfide modelling to confirm conditions within the trunk sewer.展开更多
Sewer pipe condition assessment by performing regular inspections is crucial for ensuring the systems’effective operation and maintenance.CCTV(closed-circuit television)is widely employed in North America to examine ...Sewer pipe condition assessment by performing regular inspections is crucial for ensuring the systems’effective operation and maintenance.CCTV(closed-circuit television)is widely employed in North America to examine the internal conditions of sewage pipes.Due to the extensive inventory of pipes and associated costs,it is not practical for municipalities to conduct inspections on each sanitary sewage pipe section.According to the ASCE(American Society of Civil Engineers)infrastructure report published in 2021,combined investment needs for water and wastewater systems are estimated to be$150 billion during 2016-2025.Therefore,new solutions are needed to fill the trillion-dollar investment gap to improve the existing water and wastewater infrastructure for the coming years.ML(machine learning)based prediction model development is an effective method for predicting the condition of sewer pipes.In this research,sewer pipe inspection data from several municipalities are collected,which include variables such as pipe material,age,diameter,length,soil type,slope of construction,and PACP(Pipeline Assessment Certification Program)score.These sewer pipe data exhibit a severe imbalance in pipes’PACP scores,which is considered the target variable in the development of models.Due to this imbalanced dataset,the performance of the sewer prediction model is poor.This paper,therefore,aims to employ oversampling and hyperparameter tuning techniques to treat the imbalanced data and improve the model’s performance significantly.Utility owners and municipal asset managers can utilize the developed models to make more informed decisions on future inspections of sewer pipelines.展开更多
Climate change is accelerating globally,raising significant concerns regarding the environmental risks associated with combined sewer overflows(CSOs).These rainfall events lead to the excessive discharge of multiple p...Climate change is accelerating globally,raising significant concerns regarding the environmental risks associated with combined sewer overflows(CSOs).These rainfall events lead to the excessive discharge of multiple pollutants into natural waters.However,greenhouse gas(GHG)emissions from CSOs,which are crucial for carbon neutrality in urban water systems,remain fragmented.Using the life-cycle assess-ment method expansion approach,this study breaks down the formation and discharge processes of CSOs and uncovers the underlying mechanisms driving GHG emissions during each period.Given the complex-ity and uncertainty in the spatial distribution of GHG emissions from CSOs,the development of standard monitoring and estimation methods is vital.This study identifies the factors influencing GHG emissions within the urban drainage system(UDS)and defines the interactive GHG emission boundaries and accounting framework related to CSOs.This framework is expanded to consider the hybrid nature of urban engineering and hydraulic interactions during the CSO events.Advanced modeling technologies have emerged as essential tools for predicting and managing GHG emissions from CSOs.This review pro-motes comprehensive data-driven methods for predicting GHG emissions from CSOs,fully considering the inherent heterogeneity of CSOs and the impact of multi-source contaminants discharged into aquatic environments.It emphasizes refining emission boundary definitions,novel accounting practices adapting data-driven methods,and comprehensive management strategies in line with the move toward carbon neutrality in the UDS.It advocates the adoption of solutions including advanced technologies and artifi-cial intelligent methods to mitigate CSO-related GHG emissions,stressing the significance of integrating low-carbon solutions and a comprehensive data-driven management framework in future research directions.展开更多
Urban sewer pipes are a vital infrastructure in modern cities,and their defects must be detected in time to prevent potential malfunctioning.In recent years,to relieve the manual efforts by human experts,models based ...Urban sewer pipes are a vital infrastructure in modern cities,and their defects must be detected in time to prevent potential malfunctioning.In recent years,to relieve the manual efforts by human experts,models based on deep learning have been introduced to automatically identify potential defects.However,these models are insufficient in terms of dataset complexity,model versatility and performance.Our work addresses these issues with amulti-stage defect detection architecture using a composite backbone Swin Transformer.Themodel based on this architecture is trained using a more comprehensive dataset containingmore classes of defects.By ablation studies on the modules of combined backbone Swin Transformer,multi-stage detector,test-time data augmentation and model fusion,it is revealed that they all contribute to the improvement of detection accuracy from different aspects.The model incorporating all these modules achieves the mean Average Precision(mAP)of 78.6% at an Intersection over Union(IoU)threshold of 0.5.This represents an improvement of 14.1% over the ResNet50 Faster Region-based Convolutional Neural Network(R-CNN)model and a 6.7% improvement over You Only Look Once version 6(YOLOv6)-large,the highest in the YOLO methods.In addition,for other defect detection models for sewer pipes,although direct comparison with themis infeasible due to the unavailability of their private datasets,our results are obtained from a more comprehensive dataset and have superior generalization capabilities.展开更多
Biogenic hydrogen sulfide is an odorous, toxic and corrosive gas released from sewage in sewers. To control sulfide generation and emission, nitrate is extensively applied in sewer systems for decades. However, the un...Biogenic hydrogen sulfide is an odorous, toxic and corrosive gas released from sewage in sewers. To control sulfide generation and emission, nitrate is extensively applied in sewer systems for decades. However, the unexpected sulfide rebound after nitrate addition is being questioned in recent studies. Possible reasons for the sulfide rebounds have been studied,but the mechanism is still unclear, so the countermeasure is not yet proposed. In this study, a lab-scale sewer system was developed for investigating the unexpected sulfide rebounds via the traditional strategy of nitrate addition during 195-days of operation. It was observed that the sulfide pollution was even severe in a sewer receiving nitrate addition. The mechanism for the sulfide rebound can be differentiated into short-term and long-term effects based on the dominant contribution. The accumulation of intermediate elemental sulfur in biofilm resulted in a rapid sulfide rebound via the high-rate sulfur reduction after the depletion of nitrate in a short period. The presence of nitrate in sewer promoted the microorganism proliferation in biofilm, increased the biofilm thickness, re-shaped the microbial community and enhanced biological denitrification and sulfur production, which further weakened the effect of nitrate on sulfide control during the long-term operation. An optimized biofilminitiated sewer process model demonstrated that neither the intermittent nitrate addition nor the continuous nitrate addition was a sustainable strategy for the sulfide control. To minimize the negative impact from sulfide rebounds, a(bi)monthly routine maintenance(e.g., hydraulic flushing with nitrate spike) to remove the proliferative microorganism in biofilm is necessary.展开更多
Sewer blockages are on the increase whilst water closet (WC) flush volumes are on the decrease. Furthermore, Water UK reported figures show that the actual number of properties affected by sewer flooding is on the ris...Sewer blockages are on the increase whilst water closet (WC) flush volumes are on the decrease. Furthermore, Water UK reported figures show that the actual number of properties affected by sewer flooding is on the rise. Sewer blockages can lead to sewer flooding of homes and collapse of sewers which impact negatively on social, economic and environmental factors, and therefore, they are not sustainable. Water conservation is required due to water stress but reduced water use results in less water to waste, which in turn reduces solids’ transfer in sewers. When considering reducing water usage through water conservation, these savings could be cancelled out by an increased population and the situation exacerbated by the impacts of climate change. There are issues in relation to varying design methods, a reliance on engineering judgement in sewer design, uncertainty relating to future water stress, and a lack of cross disciplinary design decision-making. Public health engineering solutions are needed to reduce the number of sewer blockages and the environmental impact of sewer flooding. This paper examines the fundamental research that have been carried out in the area of “solid transfer in sewers” resulting from “less water to waste” since the mid-20th Century. Contrary to existing literature, this paper identifies that, now more than ever, this type of research is needed to deal with the increased need for water conservation. To judge that solid transfer research is complete can be compared to supporting a statement that “water conservation is complete”.展开更多
The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several...The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several serious problems have arisen in the operation and treatment effectiveness of these facilities due to unsuitable design flow volumes and pollution loads. It is difficult to assess the optimal flow volume and pollution mass when considering both monetary and temporal limitations. The objective of this article was to characterize the discharge of storm runoff pollution from urban catchments in Korea and to estimate the probability of mass first flush （MFFn） using the storm water management model and probability density functions. As a result of the review of gauged storms for the representative using probability density function with rainfall volumes during the last two years, all the gauged storms were found to be valid representative precipitation. Both the observed MFFn and probability MFFn in BE-1 denoted similarly large magnitudes of first flush with roughly 40% of the total pollution mass contained in the first 20% of the runoff. In the case of BE-2, however, there were significant difference between the observed MFFn and probability MFFn.展开更多
The sewer system plays an important role in protecting rainfall and treating urban wastewater.Due to the harsh internal environment and complex structure of the sewer,it is difficult to monitor the sewer system.Resear...The sewer system plays an important role in protecting rainfall and treating urban wastewater.Due to the harsh internal environment and complex structure of the sewer,it is difficult to monitor the sewer system.Researchers are developing different methods,such as the Internet of Things and Artificial Intelligence,to monitor and detect the faults in the sewer system.Deep learning is a promising artificial intelligence technology that can effectively identify and classify different sewer system defects.However,the existing deep learning based solution does not provide high accuracy prediction and the defect class considered for classification is very small,which can affect the robustness of the model in the constraint environment.As a result,this paper proposes a sewer condition monitoring framework based on deep learning,which can effectively detect and evaluate defects in sewer pipelines with high accuracy.We also introduce a large dataset of sewer defects with 20 different defect classes found in the sewer pipeline.This study modified the original RegNet model by modifying the squeeze excitation(SE)block and adding the dropout layer and Leaky Rectified Linear Units(LeakyReLU)activation function in the Block structure of RegNet model.This study explored different deep learning methods such as RegNet,ResNet50,very deep convolutional networks(VGG),and GoogleNet to train on the sewer defect dataset.The experimental results indicate that the proposed system framework based on the modified-RegNet(RegNet+)model achieves the highest accuracy of 99.5 compared with the commonly used deep learning models.The proposed model provides a robust deep learning model that can effectively classify 20 different sewer defects and be utilized in real-world sewer condition monitoring applications.展开更多
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 formation of hydrogen sulfide in biofilms and sediments in sewer systems can cause severe pipe corrosions and health hazards, and requires expensive programs for its prevention. The aim of this study is to propose...The formation of hydrogen sulfide in biofilms and sediments in sewer systems can cause severe pipe corrosions and health hazards, and requires expensive programs for its prevention. The aim of this study is to propose a new control strategy and the optimal condition for sulfide elimination by intermittent nitrate dosing in sewer sediments. The study was carried out based on lab-scale experiments and batch tests using real sewer sediments. The intermittent nitrate dosing mode and the optimal control condition were investigated. The results indicated that the sulfide-intermittent-elimination strategy by nitrate dosing is advantageous for controlling sulfide accumulation in sewer sediment. The oxidation–reduction potential is a sensitive indicator parameter that can reflect the control effect and the minimum N/S（nitrate/sulfide）ratio with slight excess nitrate is necessary for optimal conditions of efficient sulfide control with lower carbon source loss. The optimal control condition is feasible for the sulfide elimination in sewer systems.展开更多
Small diameter gravity sewers(SDGS)are extensively used to collect rural sewage as they are low in cost and quick to construct.However,the characteristics of biofilms in rural SDGS are still not clear.In this study,bi...Small diameter gravity sewers(SDGS)are extensively used to collect rural sewage as they are low in cost and quick to construct.However,the characteristics of biofilms in rural SDGS are still not clear.In this study,biofilms characteristics of aerobic rural SDGS were investigated using simulations in a lab under different flow conditions and slopes.Results indic ated that the average thickness of aerobic rural SDGS biofilms was in the range of 350-650μm,decreasing at locations with variable flow and high slopes.Protein was the most abundant substance in extracellular polymeric substance of SDGS biofilms.The most abundant bacteria,Proteobacteria,Actinobacteria,and Bacteroidetes,and functional bacteria showed different distributions when analyzed through Illumina HiSeq sequencing of 16 S rRNA.The relative abundances of denitrifying bacteria,nitrite-oxidizing bacteria,and sulfate-reducing bacteria(SRB)were lower during variable flow than during stable flow.High slopes(15‰)decreased SRB presence,which could be used to mitigate H2 S accumulation in aerobic SDGS.Overall,this study describes the characteristics of aerobic rural SDGS biofilms and provides valuable suggestions for the optimal design of SDGS based on these characteristics.展开更多
This research presents the condition prediction of sewer pipes using a linear regression approach. The analysis is based on data obtained via Closed Circuit Television (CCTV) inspection over a sewer system. Informatio...This research presents the condition prediction of sewer pipes using a linear regression approach. The analysis is based on data obtained via Closed Circuit Television (CCTV) inspection over a sewer system. Information such as pipe material and pipe age is collected. The regression approach is developed to evaluate factors which are important and predict the condition using available information. The analysis reveals that the method can be successfully used to predict pipe condition. The specific model obtained can be used to assess the pipes for the given sewer system. For other sewer systems, the method can be directly applied to predict the condition. The results from this research are able to assist municipalities to forecast the condition of sewer pipe mains in an effort to schedule inspection, allocate budget and make decisions.展开更多
Severe operational problems of sediment deposition have frequently occurred in stormwater sewer systems in Shanghai city due to the flat topography of the area and serious illicit connections. To control sewer sedimen...Severe operational problems of sediment deposition have frequently occurred in stormwater sewer systems in Shanghai city due to the flat topography of the area and serious illicit connections. To control sewer sediment and its subsequential problems,optimized operation plans were proposed and an innovative performance assessment method was developed. Simula-tion results demonstrated that,through changing the way of pump operation and installing necessary actuators in the system,the optimized operations,especially batch intermittent intercept plan,effectively improved the flow velocity in the entire system in dry-weather condition. In conclusion,the optimized operation is an innovative idea for improving the performance and solving the problem of sediment deposition in the sewer system in Shanghai,China.展开更多
In order to control combined system overflow (CSO) pollution of regional sewer systems in Shanghai,a global optimal control (GOC) is presented in this study.The GOC is based on the analysis of current situation and ca...In order to control combined system overflow (CSO) pollution of regional sewer systems in Shanghai,a global optimal control (GOC) is presented in this study.The GOC is based on the analysis of current situation and can maximize the utilization of the free storage of each sub systems and decrease the frequencies and durations of CSOs and flooding.A representative regional sewer system,which is located in the northwest of Shanghai and composed of sub systems of Zhenguang,Zhenru and Tongchuan,was taken as an example to demonstrate the efficiency of GOC with hydraulic model simulation test in the two representative scenarios (Scenario Ⅰ and Ⅱ).The results indicated that a great improvement in CSO emission is obtained by using the GOC in the two scenarios,and the CSO volume of three sub systems,Zhenru,Tongchuan and Zhenguang decreases to about 37.0%,38.3% and 35.7% in Scenario Ⅰ and 47.5%,51.8% and 63.5% in Scenario Ⅱ respectively.展开更多
In periurban zones, urban wet weather discharges have been recognized as the most significant vector of pollution in aquatic environments. The discharge of this water without treatment into the aquatic environment cou...In periurban zones, urban wet weather discharges have been recognized as the most significant vector of pollution in aquatic environments. The discharge of this water without treatment into the aquatic environment could present an ecotoxicological risk for biocenosis. The aim of the INVASION project is to assess the potential ecotoxicological impact of a combined sewer overflow (CSO) on a peri-urban stream. A comparative study between upstream and downstream areas of the CSO allowed observing significant effects of this overflow on the river. We studied three layers of stream: surface water, benthic layer and hyporheic layer. To characterize the potential ecotoxicological risk of water and sediments, we used a battery of 4 bioassays: Daphnia magna, Vibrio fischeri, Brachionus calyciflorus and Heterocypris incongruens. In parallel, we measured the physico-chemical parameters: ammonium (NH4+), chromium (Cr), copper (Cu) and lead (Pb). An ecological risk is greatest for the hyporheic zone in downstream river, particularly for the solid phase. These results corroborated with the physico-chemical data obtained.展开更多
Separate sanitary sewer systems are designed to convey sewage waste from municipal areas to a central treatment facility;they are not designed to handle water associated with precipitation events. However, intercept o...Separate sanitary sewer systems are designed to convey sewage waste from municipal areas to a central treatment facility;they are not designed to handle water associated with precipitation events. However, intercept of groundwater (infiltration) and of flows through manholes or unauthorized connections (inflows) introduces rainwater into the sanitary sewer system. Infiltration/Inflow (I/I) increases the costs associated with treatment and can create additional environmental problems. Identifying and quantifying the volume I/I can be complicated and costly. A simple quantitative method was developed to quantify the extent of I/I occurring in sewer sheds. The method uses measured sewer flows, water usage, precipitation values, and land cover data to calculate the volume of extraneous flows. To assess its utility, the method was used to compare two urban sewer sheds, Holiday Knolls and Eagle View. Both sewer sheds showed evidence of I/I in excess of 200 gallons per day per inch-mile of sewer pipe (gpd/in-mile). Holiday Knolls, the older subdivision had an average I/I of 1912 gpd/in-mile, while Eagle View had an average of 1143 gpd/in-mile. The devel- oped method provided simple means to calculate I/I and to identify sewer sheds in need of repair.展开更多
The paper provides an investigation and understanding of the significance of various wastewater flows on microplastics retainment and emission to the environment. WWTPs and sewer overflows as an important pathway of m...The paper provides an investigation and understanding of the significance of various wastewater flows on microplastics retainment and emission to the environment. WWTPs and sewer overflows as an important pathway of microplastics to the environment are assessed by considering the removal of microplastics in WWTPs with different treatment processes and several sewer overflow types and their contribution to microplastic loads to recipients. On the example of the Baltic Sea basin, presented results indicate a considerable discharge of microplastic from WWTPs despite the relatively good overall removal efficiency. Results show that the discharge of microplastics from sewer overflows can be in the same magnitude as from treated wastewater although the total flow is much lower than that of treated wastewater. Sewer overflow events frequently occur and are expected to increase due to climate change and urbanization, unless infrastructure is adapted. At the same time, sewer overflows are often neglected in conventional wastewater handling.展开更多
The layout of houses and other buildings impacts the way in which foul sewer pipework is positioned internally and externally. Less water to waste through conservation measures reduces the distance that gross solids t...The layout of houses and other buildings impacts the way in which foul sewer pipework is positioned internally and externally. Less water to waste through conservation measures reduces the distance that gross solids transfer in sewers and increases the number of sewer blockages. Dwelling houses are often laid out where the solids from faecal flushes are at the head of the sewer line with other flows entering downstream. Discharges from appliances such as washing machines, dishwashers, baths, showers and kitchen/utility sinks are often not utilised in the transfer of the gross solids when they enter downstream of the faecal flushes. At present, no recommendations or specific design guidance exist regarding the design of internal building layouts relating to sewer configuration requirements. Furthermore, to date, no specific research exists which examines pipeline configuration scenarios outside buildings in terms of the link between multiple grey water discharge points and solid transfer in a sewer system. The aim of this study was to investigate sewer layout at houses in terms of maximising greywater flow in relation to solid transfer. This study showed that smart sewers are needed which utilise all the foul water leaving a building as it was found that up to 100% of greywater in some instances is completely missed out in terms of solid transfer. Consequently, optimal sewer design is far from being realised and internal building layouts should be designed with consideration of the faecal flushes and greywater flows.展开更多
Materials such as cement and composite active admixture were mixed in definite ratio to consolidate sewer sludge, which had been dried and smashed. Two kinds of solidified bodies were designed. A represented the solid...Materials such as cement and composite active admixture were mixed in definite ratio to consolidate sewer sludge, which had been dried and smashed. Two kinds of solidified bodies were designed. A represented the solidified body which had not used any composite active admixture, and B represented the one which used composite active admixture as one of its compositions. The results show that the compressive strength （28 d） of these solidified bodies can reach 30 MPa under the standard maintain condition which could be used as subgrade material. The concentration of heavy metals in solidified body was far less than identification standard for hazardous wastes of China. Heavy metals were stabilized and solidified effectively. The organic matter in these solidified bodies of 56 d was 80 percent less than that in raw sludge. A large quantity of bacteria could also be killed because of the basic condition in solidified body. Scanning electron microscope （SEM） test explained the reason that solidified body B showed better properties in all tests.展开更多
This paper was undertaken to compare eleven utilities where part or all of the utility was tested for infiltration and inflow with the intention of determining the value of data gathered from midnight investigations, ...This paper was undertaken to compare eleven utilities where part or all of the utility was tested for infiltration and inflow with the intention of determining the value of data gathered from midnight investigations, comparing</span><span style="font-family:""> </span><span style="font-family:Verdana;">potential costs (in 2020 dollars)</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> and understanding whether statistical methods can be used to predict potential problems on the system. Inflow and infiltration amounts can be identified on a utility system without significant effort. Inflow correction is robust</span><span style="font-family:""> </span><span style="font-family:Verdana;">and easy to implement (though often overlooked). After inflow is addressed, the results indicated that a midnight investigation could quickly identify portions of the sewer system in need of attention. Maps of leaky pipe sections can be identified, and commonalities in the system may become apparent. Statistical methods were used to identify high groundwater levels and lateral issues as critical issues on these systems. The methods can be utilized at other utilities to help guide them to addressing the critical issues first as opposed to focusing only on the traditional pipe lining solutions that often ignore the lateral and inflow issues that plague utility managers.展开更多
文摘The City of Calgary’s Nose Creek Sanitary Sewer Trunk Phase B project has been constructed over several years to accommodate future population growth and open more developable lands in northern Calgary.The project was divided into three phases,Phase A,B,and C,with each phase delivered by a separate consultant.Phase A was the downstream section of this project and was undertaken by Stantec Consulting.Phase B was the upstream section designed by CH2MHILL(now Jacobs)and further divided into different contracts(1 through 5).Phase C was a separate sewer called the Saddleridge Trunk sewer and this was designed by Associated Engineering.This paper covers Phase B,Contract 4,which had several unique challenges and included many innovative design and procurement solutions.One procurement strategy included a two-phase qualification package,with the initial phase to select a tunnelling contractor with the experience to deliver technical installations under rail and creeks,and the second phase,a RFP(request for proposal),to select a general contractor,with broader experience in open-cut and stormwater drainage,which were other aspects included within the project.This approach ensured that The City had the most qualified team available to complete the project.Technical challenges discussed in this paper include an oblique CPKC(Canadian Pacific Kansas City)rail and Nose Creek crossing that required independent review,and CFD(computational fluid dynamics)and hydrogen sulfide modelling to confirm conditions within the trunk sewer.
文摘Sewer pipe condition assessment by performing regular inspections is crucial for ensuring the systems’effective operation and maintenance.CCTV(closed-circuit television)is widely employed in North America to examine the internal conditions of sewage pipes.Due to the extensive inventory of pipes and associated costs,it is not practical for municipalities to conduct inspections on each sanitary sewage pipe section.According to the ASCE(American Society of Civil Engineers)infrastructure report published in 2021,combined investment needs for water and wastewater systems are estimated to be$150 billion during 2016-2025.Therefore,new solutions are needed to fill the trillion-dollar investment gap to improve the existing water and wastewater infrastructure for the coming years.ML(machine learning)based prediction model development is an effective method for predicting the condition of sewer pipes.In this research,sewer pipe inspection data from several municipalities are collected,which include variables such as pipe material,age,diameter,length,soil type,slope of construction,and PACP(Pipeline Assessment Certification Program)score.These sewer pipe data exhibit a severe imbalance in pipes’PACP scores,which is considered the target variable in the development of models.Due to this imbalanced dataset,the performance of the sewer prediction model is poor.This paper,therefore,aims to employ oversampling and hyperparameter tuning techniques to treat the imbalanced data and improve the model’s performance significantly.Utility owners and municipal asset managers can utilize the developed models to make more informed decisions on future inspections of sewer pipelines.
基金supported by the National Natural Science Foun-dation of China(52325001,52170009,and 52400114)the National Key Research and Development Program of China(2021YFC3200700 and 2021YFC3200702)+1 种基金the Program of Shanghai Academic Research Leader,China(21XD1424000)the Fundamental Research Funds for the Central Universities.
文摘Climate change is accelerating globally,raising significant concerns regarding the environmental risks associated with combined sewer overflows(CSOs).These rainfall events lead to the excessive discharge of multiple pollutants into natural waters.However,greenhouse gas(GHG)emissions from CSOs,which are crucial for carbon neutrality in urban water systems,remain fragmented.Using the life-cycle assess-ment method expansion approach,this study breaks down the formation and discharge processes of CSOs and uncovers the underlying mechanisms driving GHG emissions during each period.Given the complex-ity and uncertainty in the spatial distribution of GHG emissions from CSOs,the development of standard monitoring and estimation methods is vital.This study identifies the factors influencing GHG emissions within the urban drainage system(UDS)and defines the interactive GHG emission boundaries and accounting framework related to CSOs.This framework is expanded to consider the hybrid nature of urban engineering and hydraulic interactions during the CSO events.Advanced modeling technologies have emerged as essential tools for predicting and managing GHG emissions from CSOs.This review pro-motes comprehensive data-driven methods for predicting GHG emissions from CSOs,fully considering the inherent heterogeneity of CSOs and the impact of multi-source contaminants discharged into aquatic environments.It emphasizes refining emission boundary definitions,novel accounting practices adapting data-driven methods,and comprehensive management strategies in line with the move toward carbon neutrality in the UDS.It advocates the adoption of solutions including advanced technologies and artifi-cial intelligent methods to mitigate CSO-related GHG emissions,stressing the significance of integrating low-carbon solutions and a comprehensive data-driven management framework in future research directions.
基金supported by the Science and Technology Development Fund of Macao(Grant No.0079/2019/AMJ)the National Key R&D Program of China(No.2019YFE0111400).
文摘Urban sewer pipes are a vital infrastructure in modern cities,and their defects must be detected in time to prevent potential malfunctioning.In recent years,to relieve the manual efforts by human experts,models based on deep learning have been introduced to automatically identify potential defects.However,these models are insufficient in terms of dataset complexity,model versatility and performance.Our work addresses these issues with amulti-stage defect detection architecture using a composite backbone Swin Transformer.Themodel based on this architecture is trained using a more comprehensive dataset containingmore classes of defects.By ablation studies on the modules of combined backbone Swin Transformer,multi-stage detector,test-time data augmentation and model fusion,it is revealed that they all contribute to the improvement of detection accuracy from different aspects.The model incorporating all these modules achieves the mean Average Precision(mAP)of 78.6% at an Intersection over Union(IoU)threshold of 0.5.This represents an improvement of 14.1% over the ResNet50 Faster Region-based Convolutional Neural Network(R-CNN)model and a 6.7% improvement over You Only Look Once version 6(YOLOv6)-large,the highest in the YOLO methods.In addition,for other defect detection models for sewer pipes,although direct comparison with themis infeasible due to the unavailability of their private datasets,our results are obtained from a more comprehensive dataset and have superior generalization capabilities.
基金supported by the National Natural Science Foundation of China (No. 51638005)the Fundamental Research Funds for the Central Universities (No. 20lgzd24)+1 种基金the Guangdong Basic and Applied Basic Research of the Joint Regional Fund (No. 2019A1515110569)Guangdong Provincial International Joint Research Center on Urban Water Management and Treatment (No. 2021A0505020010)。
文摘Biogenic hydrogen sulfide is an odorous, toxic and corrosive gas released from sewage in sewers. To control sulfide generation and emission, nitrate is extensively applied in sewer systems for decades. However, the unexpected sulfide rebound after nitrate addition is being questioned in recent studies. Possible reasons for the sulfide rebounds have been studied,but the mechanism is still unclear, so the countermeasure is not yet proposed. In this study, a lab-scale sewer system was developed for investigating the unexpected sulfide rebounds via the traditional strategy of nitrate addition during 195-days of operation. It was observed that the sulfide pollution was even severe in a sewer receiving nitrate addition. The mechanism for the sulfide rebound can be differentiated into short-term and long-term effects based on the dominant contribution. The accumulation of intermediate elemental sulfur in biofilm resulted in a rapid sulfide rebound via the high-rate sulfur reduction after the depletion of nitrate in a short period. The presence of nitrate in sewer promoted the microorganism proliferation in biofilm, increased the biofilm thickness, re-shaped the microbial community and enhanced biological denitrification and sulfur production, which further weakened the effect of nitrate on sulfide control during the long-term operation. An optimized biofilminitiated sewer process model demonstrated that neither the intermittent nitrate addition nor the continuous nitrate addition was a sustainable strategy for the sulfide control. To minimize the negative impact from sulfide rebounds, a(bi)monthly routine maintenance(e.g., hydraulic flushing with nitrate spike) to remove the proliferative microorganism in biofilm is necessary.
文摘Sewer blockages are on the increase whilst water closet (WC) flush volumes are on the decrease. Furthermore, Water UK reported figures show that the actual number of properties affected by sewer flooding is on the rise. Sewer blockages can lead to sewer flooding of homes and collapse of sewers which impact negatively on social, economic and environmental factors, and therefore, they are not sustainable. Water conservation is required due to water stress but reduced water use results in less water to waste, which in turn reduces solids’ transfer in sewers. When considering reducing water usage through water conservation, these savings could be cancelled out by an increased population and the situation exacerbated by the impacts of climate change. There are issues in relation to varying design methods, a reliance on engineering judgement in sewer design, uncertainty relating to future water stress, and a lack of cross disciplinary design decision-making. Public health engineering solutions are needed to reduce the number of sewer blockages and the environmental impact of sewer flooding. This paper examines the fundamental research that have been carried out in the area of “solid transfer in sewers” resulting from “less water to waste” since the mid-20th Century. Contrary to existing literature, this paper identifies that, now more than ever, this type of research is needed to deal with the increased need for water conservation. To judge that solid transfer research is complete can be compared to supporting a statement that “water conservation is complete”.
文摘The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several serious problems have arisen in the operation and treatment effectiveness of these facilities due to unsuitable design flow volumes and pollution loads. It is difficult to assess the optimal flow volume and pollution mass when considering both monetary and temporal limitations. The objective of this article was to characterize the discharge of storm runoff pollution from urban catchments in Korea and to estimate the probability of mass first flush （MFFn） using the storm water management model and probability density functions. As a result of the review of gauged storms for the representative using probability density function with rainfall volumes during the last two years, all the gauged storms were found to be valid representative precipitation. Both the observed MFFn and probability MFFn in BE-1 denoted similarly large magnitudes of first flush with roughly 40% of the total pollution mass contained in the first 20% of the runoff. In the case of BE-2, however, there were significant difference between the observed MFFn and probability MFFn.
基金supported by Basic ScienceResearch Program through the National Research Foundation ofKorea(NRF)funded by the Ministry of Education(2020R1A6A1A03038540)by Korea Institute of Planning and Evaluation for Technology in Food,Agriculture,Forestry and Fisheries(IPET)through Digital Breeding Transformation Technology Development Program,funded by Ministry of Agriculture,Food and Rural Affairs(MAFRA)(322063-03-1-SB010)by the Technology development Program(RS-2022-00156456)funded by the Ministry of SMEs and Startups(MSS,Korea).
文摘The sewer system plays an important role in protecting rainfall and treating urban wastewater.Due to the harsh internal environment and complex structure of the sewer,it is difficult to monitor the sewer system.Researchers are developing different methods,such as the Internet of Things and Artificial Intelligence,to monitor and detect the faults in the sewer system.Deep learning is a promising artificial intelligence technology that can effectively identify and classify different sewer system defects.However,the existing deep learning based solution does not provide high accuracy prediction and the defect class considered for classification is very small,which can affect the robustness of the model in the constraint environment.As a result,this paper proposes a sewer condition monitoring framework based on deep learning,which can effectively detect and evaluate defects in sewer pipelines with high accuracy.We also introduce a large dataset of sewer defects with 20 different defect classes found in the sewer pipeline.This study modified the original RegNet model by modifying the squeeze excitation(SE)block and adding the dropout layer and Leaky Rectified Linear Units(LeakyReLU)activation function in the Block structure of RegNet model.This study explored different deep learning methods such as RegNet,ResNet50,very deep convolutional networks(VGG),and GoogleNet to train on the sewer defect dataset.The experimental results indicate that the proposed system framework based on the modified-RegNet(RegNet+)model achieves the highest accuracy of 99.5 compared with the commonly used deep learning models.The proposed model provides a robust deep learning model that can effectively classify 20 different sewer defects and be utilized in real-world sewer condition monitoring applications.
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supported by the National Natural Science Foundation of China (No. 50908131)the Major Science and Technology Program for Water Pollution Control and Treatment of China (No. 2011ZX07301-002)Tsinghua University Initiative Scientific Research Program (No.20121087922)
文摘The formation of hydrogen sulfide in biofilms and sediments in sewer systems can cause severe pipe corrosions and health hazards, and requires expensive programs for its prevention. The aim of this study is to propose a new control strategy and the optimal condition for sulfide elimination by intermittent nitrate dosing in sewer sediments. The study was carried out based on lab-scale experiments and batch tests using real sewer sediments. The intermittent nitrate dosing mode and the optimal control condition were investigated. The results indicated that the sulfide-intermittent-elimination strategy by nitrate dosing is advantageous for controlling sulfide accumulation in sewer sediment. The oxidation–reduction potential is a sensitive indicator parameter that can reflect the control effect and the minimum N/S（nitrate/sulfide）ratio with slight excess nitrate is necessary for optimal conditions of efficient sulfide control with lower carbon source loss. The optimal control condition is feasible for the sulfide elimination in sewer systems.
基金supported by the National Natural Science Foundation of China(Nos.51838013,51808536)the National Key R&D Program of China(No.2016YFC0400804)
文摘Small diameter gravity sewers(SDGS)are extensively used to collect rural sewage as they are low in cost and quick to construct.However,the characteristics of biofilms in rural SDGS are still not clear.In this study,biofilms characteristics of aerobic rural SDGS were investigated using simulations in a lab under different flow conditions and slopes.Results indic ated that the average thickness of aerobic rural SDGS biofilms was in the range of 350-650μm,decreasing at locations with variable flow and high slopes.Protein was the most abundant substance in extracellular polymeric substance of SDGS biofilms.The most abundant bacteria,Proteobacteria,Actinobacteria,and Bacteroidetes,and functional bacteria showed different distributions when analyzed through Illumina HiSeq sequencing of 16 S rRNA.The relative abundances of denitrifying bacteria,nitrite-oxidizing bacteria,and sulfate-reducing bacteria(SRB)were lower during variable flow than during stable flow.High slopes(15‰)decreased SRB presence,which could be used to mitigate H2 S accumulation in aerobic SDGS.Overall,this study describes the characteristics of aerobic rural SDGS biofilms and provides valuable suggestions for the optimal design of SDGS based on these characteristics.
文摘This research presents the condition prediction of sewer pipes using a linear regression approach. The analysis is based on data obtained via Closed Circuit Television (CCTV) inspection over a sewer system. Information such as pipe material and pipe age is collected. The regression approach is developed to evaluate factors which are important and predict the condition using available information. The analysis reveals that the method can be successfully used to predict pipe condition. The specific model obtained can be used to assess the pipes for the given sewer system. For other sewer systems, the method can be directly applied to predict the condition. The results from this research are able to assist municipalities to forecast the condition of sewer pipe mains in an effort to schedule inspection, allocate budget and make decisions.
基金Project (No. 2008ZX07317-001) supported by the Special Grand National Science-Technology Project for Water Pollution Control and Treatment, China
文摘Severe operational problems of sediment deposition have frequently occurred in stormwater sewer systems in Shanghai city due to the flat topography of the area and serious illicit connections. To control sewer sediment and its subsequential problems,optimized operation plans were proposed and an innovative performance assessment method was developed. Simula-tion results demonstrated that,through changing the way of pump operation and installing necessary actuators in the system,the optimized operations,especially batch intermittent intercept plan,effectively improved the flow velocity in the entire system in dry-weather condition. In conclusion,the optimized operation is an innovative idea for improving the performance and solving the problem of sediment deposition in the sewer system in Shanghai,China.
文摘In order to control combined system overflow (CSO) pollution of regional sewer systems in Shanghai,a global optimal control (GOC) is presented in this study.The GOC is based on the analysis of current situation and can maximize the utilization of the free storage of each sub systems and decrease the frequencies and durations of CSOs and flooding.A representative regional sewer system,which is located in the northwest of Shanghai and composed of sub systems of Zhenguang,Zhenru and Tongchuan,was taken as an example to demonstrate the efficiency of GOC with hydraulic model simulation test in the two representative scenarios (Scenario Ⅰ and Ⅱ).The results indicated that a great improvement in CSO emission is obtained by using the GOC in the two scenarios,and the CSO volume of three sub systems,Zhenru,Tongchuan and Zhenguang decreases to about 37.0%,38.3% and 35.7% in Scenario Ⅰ and 47.5%,51.8% and 63.5% in Scenario Ⅱ respectively.
文摘In periurban zones, urban wet weather discharges have been recognized as the most significant vector of pollution in aquatic environments. The discharge of this water without treatment into the aquatic environment could present an ecotoxicological risk for biocenosis. The aim of the INVASION project is to assess the potential ecotoxicological impact of a combined sewer overflow (CSO) on a peri-urban stream. A comparative study between upstream and downstream areas of the CSO allowed observing significant effects of this overflow on the river. We studied three layers of stream: surface water, benthic layer and hyporheic layer. To characterize the potential ecotoxicological risk of water and sediments, we used a battery of 4 bioassays: Daphnia magna, Vibrio fischeri, Brachionus calyciflorus and Heterocypris incongruens. In parallel, we measured the physico-chemical parameters: ammonium (NH4+), chromium (Cr), copper (Cu) and lead (Pb). An ecological risk is greatest for the hyporheic zone in downstream river, particularly for the solid phase. These results corroborated with the physico-chemical data obtained.
文摘Separate sanitary sewer systems are designed to convey sewage waste from municipal areas to a central treatment facility;they are not designed to handle water associated with precipitation events. However, intercept of groundwater (infiltration) and of flows through manholes or unauthorized connections (inflows) introduces rainwater into the sanitary sewer system. Infiltration/Inflow (I/I) increases the costs associated with treatment and can create additional environmental problems. Identifying and quantifying the volume I/I can be complicated and costly. A simple quantitative method was developed to quantify the extent of I/I occurring in sewer sheds. The method uses measured sewer flows, water usage, precipitation values, and land cover data to calculate the volume of extraneous flows. To assess its utility, the method was used to compare two urban sewer sheds, Holiday Knolls and Eagle View. Both sewer sheds showed evidence of I/I in excess of 200 gallons per day per inch-mile of sewer pipe (gpd/in-mile). Holiday Knolls, the older subdivision had an average I/I of 1912 gpd/in-mile, while Eagle View had an average of 1143 gpd/in-mile. The devel- oped method provided simple means to calculate I/I and to identify sewer sheds in need of repair.
文摘The paper provides an investigation and understanding of the significance of various wastewater flows on microplastics retainment and emission to the environment. WWTPs and sewer overflows as an important pathway of microplastics to the environment are assessed by considering the removal of microplastics in WWTPs with different treatment processes and several sewer overflow types and their contribution to microplastic loads to recipients. On the example of the Baltic Sea basin, presented results indicate a considerable discharge of microplastic from WWTPs despite the relatively good overall removal efficiency. Results show that the discharge of microplastics from sewer overflows can be in the same magnitude as from treated wastewater although the total flow is much lower than that of treated wastewater. Sewer overflow events frequently occur and are expected to increase due to climate change and urbanization, unless infrastructure is adapted. At the same time, sewer overflows are often neglected in conventional wastewater handling.
文摘The layout of houses and other buildings impacts the way in which foul sewer pipework is positioned internally and externally. Less water to waste through conservation measures reduces the distance that gross solids transfer in sewers and increases the number of sewer blockages. Dwelling houses are often laid out where the solids from faecal flushes are at the head of the sewer line with other flows entering downstream. Discharges from appliances such as washing machines, dishwashers, baths, showers and kitchen/utility sinks are often not utilised in the transfer of the gross solids when they enter downstream of the faecal flushes. At present, no recommendations or specific design guidance exist regarding the design of internal building layouts relating to sewer configuration requirements. Furthermore, to date, no specific research exists which examines pipeline configuration scenarios outside buildings in terms of the link between multiple grey water discharge points and solid transfer in a sewer system. The aim of this study was to investigate sewer layout at houses in terms of maximising greywater flow in relation to solid transfer. This study showed that smart sewers are needed which utilise all the foul water leaving a building as it was found that up to 100% of greywater in some instances is completely missed out in terms of solid transfer. Consequently, optimal sewer design is far from being realised and internal building layouts should be designed with consideration of the faecal flushes and greywater flows.
文摘Materials such as cement and composite active admixture were mixed in definite ratio to consolidate sewer sludge, which had been dried and smashed. Two kinds of solidified bodies were designed. A represented the solidified body which had not used any composite active admixture, and B represented the one which used composite active admixture as one of its compositions. The results show that the compressive strength （28 d） of these solidified bodies can reach 30 MPa under the standard maintain condition which could be used as subgrade material. The concentration of heavy metals in solidified body was far less than identification standard for hazardous wastes of China. Heavy metals were stabilized and solidified effectively. The organic matter in these solidified bodies of 56 d was 80 percent less than that in raw sludge. A large quantity of bacteria could also be killed because of the basic condition in solidified body. Scanning electron microscope （SEM） test explained the reason that solidified body B showed better properties in all tests.
文摘This paper was undertaken to compare eleven utilities where part or all of the utility was tested for infiltration and inflow with the intention of determining the value of data gathered from midnight investigations, comparing</span><span style="font-family:""> </span><span style="font-family:Verdana;">potential costs (in 2020 dollars)</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> and understanding whether statistical methods can be used to predict potential problems on the system. Inflow and infiltration amounts can be identified on a utility system without significant effort. Inflow correction is robust</span><span style="font-family:""> </span><span style="font-family:Verdana;">and easy to implement (though often overlooked). After inflow is addressed, the results indicated that a midnight investigation could quickly identify portions of the sewer system in need of attention. Maps of leaky pipe sections can be identified, and commonalities in the system may become apparent. Statistical methods were used to identify high groundwater levels and lateral issues as critical issues on these systems. The methods can be utilized at other utilities to help guide them to addressing the critical issues first as opposed to focusing only on the traditional pipe lining solutions that often ignore the lateral and inflow issues that plague utility managers.
