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Municipal wastewater may contain toxic substances that have a negative impact on biological treatment processes and receiving waters. This paper presents the wastewater toxicity test results from the Lodz hybrid sewage system. Wastewater is discharged to surface waters through a treatment plant, but also during wet weather, partially without treatment by combined sewer overflows. The research was carried out using the ToxTrakTM method with the use of the microbial community of activated sludge from the wastewater treatment plant in Lodz. The median toxicity, expressed as the degree of inhibition, ranged from 16.0% to 30.7%, but sometimes exceeded 50%. Higher toxicity was observed in wet weather than in dry weather. Seasonal variability was found but typical daily variability was not observed. In the case of sewage samples with the degree of inhibition above 40%, a significant correlation was found with chromium concentration and non-ionic surfactants (Pearson's coefficient correlation above 0.7). [ABSTRACT FROM AUTHOR]

The present work aims to investigate the effect of pipe roughness on the construction cost of sewer networks in steep terrains. To achieve this objective, a sensitivity analysis was performed, wherein a sewer network was designed with different pipe roughnesses and varying terrain slopes to simulate four distinct steep terrains. In addition, this study considers the effect of new pipes with very high roughnesses that have appeared on the market in recent years, evaluating their influence on sewer network design and construction cost in steep terrains. The sewer networks were designed using an existing methodology for an optimal design that includes drop manholes if required to meet all the hydraulic constraints. The effect of pipe roughness was tested in two sewer networks from distinct sectors of Bogotá, Colombia. Practical Applications: This study has relevance when considering its ability to lead to the expansion of the sewer service, particularly in hilly regions. The use of higher roughness pipes as a result of this finding has a direct impact on reducing the need for drop manholes, leading to a significant reduction in associated costs. This reduction in costs is of paramount importance in the viability and execution of sewer projects in communities facing significant financial constraints. By minimizing costs, this approach not only optimizes project efficiency but also facilitates access to basic sanitation services in geographic areas previously considered difficult to address. Consequently, this research not only improves sewer systems but also contributes to community development. [ABSTRACT FROM AUTHOR]

Fieldwork was carried out in the western area of Edmonton, Alberta, Canada to assess the H2S contribution of a long force main and to investigate the source of H2S generation in a complex sewer network. The study sewer trunk has a length of 10 km, a diameter of up to 1.95 m, and flow rate of up to 0.6 m3/s. In the upstream, there is a 5.6 km forcemain, and the pump station operation can cause a sudden increase of H2S in the sewer air of the discharge manholes to reach 500 ppm. Wastewater samples were collected in 14 manholes in the sewer network and analyzed for sulfide and other relevant parameters. The maximum values of sulfide were 9.7 mg S/L and pH remained mostly neutral. For predicting the sulfide generation rate, an empirical model was applied with readily biodegradable organic matter. Then the emission of H2S in gravity pipes was investigated, and it was found over 90% of H2S stayed in the liquid phase when wastewater flowed in gravity sewer pipes. Finally, the mass transfer in a drop structure of 8 m was investigated. The liquid phase H2S concentration in the upstream was 2.6 times that of the downstream, and about 62% of the H2S was released in this drop structure indicating the significant emission of H2S in drop structures. [ABSTRACT FROM AUTHOR]

This paper explores Hull's histories of living with water and flood in the period between the foundation of the town in the 1260s and c. 1700, examining how the inhabitants, Corporation and Commissioners of Sewers managed and governed water in order to survive and thrive in a risky yet resilient estuarine environment. It does that as part of a bigger project utilising 'learning histories' drawing on Hull's 800-year experience of living with water and flood to drive climate awareness and flood resilience in a city which has experienced major flooding in recent years and is increasingly vulnerable in the face of future climate change. Here, we use civic and other records to reconstruct a flood timeline for medieval and early modern Kingston-Upon-Hull, revealing a history of repeated flood events impacting the town and surrounding area in the centuries after its foundation in c. 1260. We explore who managed and governed water and flood risk, and how this was achieved, arguing that water management was a pervasive concern as well as a collective and shared responsibility which ultimately generated a 'living with water mentality'. [ABSTRACT FROM AUTHOR]

Determinations of radioactivity and stable element contents in outlet waters taken from dams (Çamlıdere, Kurtboğazı, Kesikköprü, Çubuk-2) and drinking waters from water treatment plants (İvedik, Pursaklar and Çubuk) of Ankara Water and Sewerage Administration (ASKİ) were performed by using MPC-9604 multi-detector alpha/beta (α/β) counting system, inductively coupled plasma–mass–mass spectrometer and graphite furnace atomic absorption spectrometer. Gross alpha and beta activity levels and element concentrations found in samples were compared with maximum permissible values given by World Health Organization, United State Environmental Protection Agency, Turkish Standards and Türkiye Regulation on Water for Human Consumption. [ABSTRACT FROM AUTHOR]

The potential for corrosion and odor emissions from a combined sewer interceptor system in Northwest Chicago was investigated. Seven manholes along the interceptor system were selected as monitoring locations, and eight critical physical-chemical and biological parameters were measured semiweekly at each location for four weeks during the morning and afternoon hours. Statistical analyses were performed to determine the diurnal variability of 5-day biochemical oxygen demand (BOD5), as well as the variability of total sulfide with respect to BOD5 and the sewer flow rates. Subsequently, the Pomeroy–Parkhurst mathematical model was used to predict the change in total sulfide concentration in a mile-long segment of the interceptor system. The model was calibrated by modifying the sulfide flux coefficient in the generation term to reflect the conditions in these interceptors, such that the measured values and model predictions were in agreement. A strong linear relationship between the system's wastewater flow and water quality characteristics and the modified sulfide flux coefficient was found (R2=0.828). With limited wastewater characteristic data, the modified Pomeroy–Parkhurst model can be used in predicting the change in total sulfide concentrations for this interceptor. [ABSTRACT FROM AUTHOR]

Blockage detection in circular open channels (partially filled pipes, e.g., gravity sewer pipes) has gained increasing interest in the water industry. While there have been significant advancements in monitoring technologies for such systems (e.g., smart sewer systems), there is a lack of quantification of the hydraulic impact of partial blockages in circular pipes, which is a limiting factor for cost-effective detection. This study presents and validates a numerical framework to quantify the changes in water depth caused by extended bottom blockages in circular open channels. The analysis is based primarily on continuity and energy conservation with the assumption of a lossless transition at the blockage. The proposed approach can determine the critical blockage height that would induce choking, therefore a change in the upstream depth. It can also calculate the changed upstream water depth for various bottom blockage height values (above the critical height) for both subcritical and supercritical conditions. The proposed approach is numerically implemented and then validated through a series of laboratory experiments under the subcritical flow condition (which is the most common condition for gravity sewer systems). The numerically determined water depth results are consistent with the experimental results, which confirms that the proposed approach can accurately estimate the new upstream depth under the choking condition induced by a bottom blockage in circular open channels. The results contribute to advancing the hydraulic understanding in circular open channels with extended partial blockages, which is useful in the development of smart sewer technologies. Practical Applications: Spills and overflows out of the gravity sewer system damage the environment and bring risks to public health. The problem is typically caused by partial blockages, which can reduce the flow capacity of the sewer pipe and induce higher-than-designed flow depth on the upstream of the blockage (known as choked flow condition). This study helps water engineers and operators to understand how an extended bottom blockage affects the flow condition just upstream of the blockage in a circular gravity sewer pipe. Charts have been presented to enable the determination of (1) the critical height of an extended bottom blockage that would induce choking; (2) the expected upstream flow depth for blockages with various heights, with a given flow rate under choked flow condition; and (3) the expected upstream flow depth for various flow rates, with a given blockage height under choked flow condition. The results can be used to evaluate the risk of bottom blockage-induced spill for sewer pipes with various sizes, slopes and flow rates (e.g., some may be more tolerant to bottom blockages while some may be more sensitive). This information can then be used to prioritize preventative measures such as sewer depth monitoring or regular cleaning. [ABSTRACT FROM AUTHOR]

The unplanned and rapid expansion of metropolitan areas reduces accessibility to existing and often outdated centralized water and wastewater systems. In this context, sanitation policies that focus exclusively on centralized systems become expensive and unfeasible. Using Q methodology, we identified three different social perspectives on onsite wastewater treatment systems (OWTS) in the metropolitan area of the Lerma Valley in northern Argentina. We focused our analysis on the legal, environmental, and technical aspects of onsite sanitation. The perspectives found were: 'OWTS have advantages', 'Hard path for sewerage', and 'Process before technology'. We describe the perspectives identified and we provide an analysis of their differences and similarities to discuss their possible policy implications for our study area and comparable regions in the country and beyond. [ABSTRACT FROM AUTHOR]

Traditional approaches devoted to upgrading the sewerage system functionality are highly costly and time demanding. Thus, the implementation of comprehensive modelling approaches can be intended as an effective and economically viable strategy to detect and outdo the critical issues of the networks. This paper presents an integrated procedure to monitor and simulate the network's performance, based on the coupling of Supervisory Control and Data Acquisition (SCADA) networks for data collecting and monitoring, with hydraulic simulations by the Storm Water Management Model 5.1 (EPA-SWMM) solver. The drawbacks of the network are then assessed by proposing several upgrades to improve the system. The proposed strategy was applied to the Nora-Noreña sewerage system, located in North Spain. Results show the potentiality of the methodology in reducing sewer network maximum filling degree requirements and overflows into the receiving water bodies. [ABSTRACT FROM AUTHOR]

Key Takeaways: Biennial data from 2017 to 2023 show that water and sewer prices increased substantially, from an average combined monthly price of $79.39 in 2017 to $95.02 in 2023 at 6,200 gallons per month for single‐family residential customers. Water rate structures became more regressive during that time, with utilities collecting an increasing share of revenue through fixed charges and less revenue through volumetric charges. Average low‐income affordability in the United States has worsened over the past six years, mainly driven by extreme unaffordability in a small minority of utilities. [ABSTRACT FROM AUTHOR]

Combined sewer overflow (CSO) control strategies are commonly selected relying on optimization or multicriteria analysis. A methodology is proposed in this paper for selecting and evaluating the solutions to mitigate stormwater problems in combined sewer systems (CSSs) based on the understanding and rigorous diagnosis of the causes of the observed problems using hydrological/hydraulic simulations. The methodology was applied to a sewer catchment near Montreal (Canada) in order to reduce the magnitude and recurrence of sewer surcharge and local flooding without increasing the recurrence of CSOs. Two types of control strategies were considered: (1) large-scale solutions, i.e., redirection of stormwater inflows and separation of the CSS; and (2) source control solutions including both green and gray infrastructure. These solutions were evaluated through a comparative analysis of nine scenarios. Based on the results, source control solutions could be considered as the most effective interventions on the studied catchment for eliminating or significantly reducing the occurrence of sewer surcharge (from an average of 6.7 to 2.6) and surface flooding on local streets (from an average of 3.5 to 0.4 per year). The developed methodology is a valuable tool to be applied to other urban drainage catchments that encounter problems similar to those observed on the studied catchment. [ABSTRACT FROM AUTHOR]

This study investigates public attitudes towards the use of human excretion-based fertiliser (HEBF) in agriculture. Focusing on England and Japan, countries with contrasting histories of nightsoil use, we conducted representative surveys to understand public acceptance and sex-based differences in attitudes. Our findings reveal significant cultural and sex-based disparities in the willingness to utilize HEBF. The Japanese are more accepting of using HEBF for food production, with fewer health concerns, compared to the English. However, English respondents are more open to using HEBF in public parks. The study emphasises the need for further research on societal perceptions and highlights the importance of cultural context in adopting sustainable practices like HEBF in agriculture.

Infrastructure deterioration is a threat to developed countries, emphasizing the need for effective management techniques. In particular, the leakage of aged domestic sewer pipeline is a major health issue, yet there is a lack of markers to identify domestic leakage. We studied the pollution in urban waters resulting from domestic sewage leakage into storm drainages. We monitored caffeine, fragrance substances and polycyclic aromatic hydrocarbons (PAHs) in the storm discharge points in five urban districts having separate sewer systems aged from 10 to over 40 years. Results show that caffeine and fragrance concentrations tended to increase with sewer system age. For instance, caffeine concentrations in the areas of sewer systems over 40 years old were at least two orders of magnitude higher than in 10-year-old sewer systems, and were as high as 1–10% of domestic sewage, strongly suggesting the leakage of domestic sewer pipelines. PAHs exhibited consistent patterns across the districts. Overall, we observe that sewer leaking processes can be distinguished by analyzing the levels of organic pollutants. [ABSTRACT FROM AUTHOR]

Sewer concrete structures are vulnerable to acidic corrosion due to the biological oxidation of sulfide in the wastewater to sulfuric acid. The use of photosynthetic bacteria in the coating layer on the sewer concrete is proposed to be an effective approach to prevent such corrosion. Here we report two strains, PN6 and PN7, isolated from a drainage system in Hanoi that were identified as Rhodopseudomonas palustris PN6 and Rhodobacter capsulatus PN7 based on a comparative analysis of the 16S rDNA and pufM gene sequences. Both strains performed versatile metabolic paths, including anoxygenic and microaerophilic phototrophy and aerobic chemotrophy, allowing them to adapt to the fluctuating sewer conditions. Furthermore, they exhibited notable capability of oxidizing sulfide and producing glycocalyx, and therefore were able to prevent concrete corrosion by scavenging sulfide and reducing the production of sulfuric acid, at the same time sealing the tiny cracks on the concrete surface and preventing further attack of the corrosive agents. Two strains grew well at an alkali pH of 9 and formed biofilm extensively, and therefore can be incorporated into porous material vermiculite, allowing them to survive in the coating mortar. The protective effect of coating mortar containing strains PN6 or PN7 singly or in a combination of both incorporated in vermiculite was demonstrated in a laboratory model simulating the sewer environment with an acidic vapor atmosphere. Without bacteria in the coating mortar, the concrete surface suffered severe corrosion with spots of 0.01–0.2 mm in width and up to 4.5 mm in length clustering in rafts of 10–70 mm2 , whereas the concrete surface coated by bacteria-containing mortar was intact to corrosion. The study proposed the possibility of applying purple nonsulfur bacteria (PNSB) to protect sewer concrete, and also prolong the service life of these important structures. Practical Applications: Sewer concrete systems are daily attacked by acidic corrosion established via the biological oxidation of sulfide to sulfuric acid. The repair is generally costly and has difficulties in implementation. The use of PNSB with the capabilities of scavenging H2S and producing exopolysaccharide (EPS) for the development of a coating layer would be a feasible approach to constrain the corrosion process. Suitable strains of PNSB such as the two strains Rhodopseudomonas palustris PN6 and Rhodobacter capsulatus PN7 reported in this study are supposed to be incorporated in a porous material like vermiculite before being added to the coating mortar to better stabilize and adapt to the harsh conditions of the coating layer. These types of PNSB can survive in the coating layer and multiply by utilizing organic carbon and sulfide from wastewater with the production of sulfur (instead of sulfuric acid) and glycocalyx that can instantly seal the tiny corrosion spots and prevent further corrosion attacks. This approach is supposed to be a prevention solution to increase the service durability of sewer concrete systems and reduce the need for repair implementation. [ABSTRACT FROM AUTHOR]

This study partially replaced the clay with sewer sludge (SS) and rice husk (RH-SS) to make fired bricks. The brick samples were examed in terms of shrinkage, water absorption, and compressive strength. Besides, they were analyzed via XRD and metal extraction to determine the heavy metal residuals in the products. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight. These brick samples complied with the technical standard for clay brick production, in which the compressive strength was more than 7.5 MPa, water absorption was from 11–16%, and the linear shrinkage was all less than 5%. The rice husk addition helped mitigate the heavy metal residuals in the bricks and leaching liquid, in which all the values were lower than the US-EPA maximum concentration of contaminants for toxicity characteristics. Implications: Previous studies have proved the possibility of mixing sewage sludge from different origins (sewage sludge, river sediment, canal sediment, sewer sediment, etc.) with clay and some wastes to make bricks. In which, mostof the studies used sewage sludge from wastewater treatment plants, very fewdealt with lake/river or sewer sediment. This study shall be the first to study the possibility of employing sewer sediments with the addition of rice husk powder to achieve two targets, including (1) the reuse of biowaste and sludge for brick fabrication and (2) the reduction of heavy metals in final calcined bricks. Different ratios of the rice-husk blended sewer sludge (RH-SS) – clay mixture shall be tested to find the optimized compositions. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight, which meant reduce 30% of clay in the brick production. The final products were proved to meet the quality standard in terms of compressive strength (more than 10 MPa), water absorption(from 11–16%), and the linear shrinkage (less than 5%). Larger scale of this study can be an evident to recommend for policy change in the waste reuse in construction field. [ABSTRACT FROM AUTHOR]

Air in the headspace of sewer laterals can be driven by the flowing sewage as well as air pressure. In this study, the openings on manholes for air flow are approximated as a thin continuous slot at the laterals. In this way, the governing equations can be solved analytically for infinitely long laterals without water flow. For cases with water flow, a numerical solution is developed. It is found that the air flow pattern in a long lateral can be categorized into three zones. The zone closest to the trunk is defined as the "zone of influence," where the air flow in the lateral is dominated by air pressure, and the air pressure and air velocity decay exponentially in the lateral. The second zone is named as "zone of equilibrium" where the air pressure gradient is zero and the air flow is only driven by the drag of water and can be calculated analytically. The air flow zone farthest from the trunk is defined as the "zone of induction" where the air is inducted into the system for mass balance in the system. An explicit fitting expression on the air velocity and water velocity in a long lateral is provided. A graphic solution for air velocity and zone of influence is also developed for a quick estimation on the air movement in sewer laterals. [ABSTRACT FROM AUTHOR]

This study conducted experiments to investigate the impact of bottom obstacles, specifically broad-crest weir-type and cylindrical obstacles, on the flow within a sewer pipe. It was observed that these two types of obstacles, when possessing the same cross-sectional area and length, exhibited nearly equivalent hydraulic responses for both supercritical and subcritical flows. The obstacle height was found to be the primary factor responsible for choking and the transition between different flow regimes. The results of the one-dimensional analysis show that the threshold value of obstacle height depends on the approaching flow conditions, including the Froude number and the filling ratio that is defined as the flow depth to the pipe diameter. In the context of a partially blocked sewer, the relationships established by using the one-dimensional model between the size of the bottom obstacle and the inflow characteristics enable the identification of flow regimes, assessment of reduced hydraulic capacity, and evaluation of local energy loss. The findings of this study elucidate the hydraulic behavior of obstructed sewers, contributing to the development of more effective strategies for the identification of obstructions through monitoring data. [ABSTRACT FROM AUTHOR]

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This paper presents a Fault-Tolerant Model Predictive Control (FTMPC) algorithm applied to a simulation model for sewer networks. The aim of this work is to preserve the operation of the predictive controller as much as possible, in accordance with its operational objectives, when there may be anomalies affecting the elements of the control system, mainly sensors and actuators. For this purpose, a fault detection and diagnosis system (FDD) based on a moving window principal component analysis technique (MWPCA) will be developed to provide an online fault monitoring solution for large-scale complex processes (e.g., sewer systems) with dynamically changing characteristics, and a reconfiguration algorithm for the MPC controller taking advantage of its own features such as constraint handling. Comparing the results obtained considering various types of faults, with situations of normal controlled operation and with the behavior of the sewer network when no control is applied, will allow some conclusions to be drawn at the end. [ABSTRACT FROM AUTHOR]

The article presents information on the history of the Environmental Protection Agency (EPA). The EPA was aware that water and sewer services are essential for neighborhood livability and understood the significant costs associated with their upkeep and development. Yet, despite recognizing that its grant program had major implications for racial segregation in land use, the EPA treated civil rights as optional rather than mandatory. The author states that this approach mirrored the evasion of responsibility seen in other federal agencies, as highlighted by Christopher Bonastia, who noted that civil rights often lack meaningful enforcement when they become politically or economically costly. The EPA’s inaction, despite knowing the harm caused by its grants, underscores the deep connections between environmental protection and structural racism.

This article explores how innovation logics infiltrate problem and value definitions in maintenance and repair, and how innovation itself depends on considerable, often invisible care work beyond the seemingly smooth entrepreneurial narratives. We build on a growing body of work in STS that investigates the relationship between innovation and maintenance and repair. This literature argues that the obsession with innovation crowds out attention to maintenance, that innovation creates future obligations of maintenance that are often not factored into technological promises, and that ordinary maintenance and repair practices are often innovative in their own right. Empirically, we explore a case where maintenance and repair become the explicit target of high-level, high-tech innovation initiatives and how, as a result, innovation logics colonize maintenance practices. Conceptually, we explore how repair and maintenance sensitivities can be applied to innovation practices to reveal the invisible work needed to align innovation instruments with socio-material and institutional configurations. Drawing on an in-depth case study of sewer inspection robots in Barcelona, we find that attempts to innovate maintenance require a symmetric effort to maintain innovation. In our case study, innovation processes as deployed by the European Commission, research consortia, and companies required substantial repair work to function reliably in specific settings. Our study shows how divergent understandings of the public good in innovation and maintenance contexts may lead to significant tensions, and that much can be gained analytically from not treating innovation and maintenance as opposites. [ABSTRACT FROM AUTHOR]

This paper proposes a methodology for the optimal design of series of sewer pipes including pumping stations. It employs a Shortest Path Algorithm to select the optimal combination of pipe diameters and invert elevations, as well as the optimal pumping features such as the number of pumps, location, and pumping head. The methodology is intended to be applied to the design of any sewer series. Although these are uncommon in real infrastructure, the study allows an analysis of the effect of pipe roughness, inflows, and pipe length on the total cost of the system and pumping features. The methodology was tested in theoretical series of 10 and 20 pipes as well as in a real series that is part of the sewer system of Bogotá, Colombia. The resulting designs suggested that using smooth pipes and reducing the pumping flow rate would decrease the cost of sewer systems in flat terrain. [ABSTRACT FROM AUTHOR]

Disasters caused by heavy rainfalls are of growing concern to researchers and government officials. While many studies have provided details of rainstorm-induced risks and efficient strategies for stormwater management, there is still a lack of attention to how the interactions between urban sewer systems and road networks during precipitation events affect sewer system performance and road inundation. To fill this gap, we have developed an integrated model that combines hydraulic characteristics and the topological structure of a sewer-road network system to explore the behaviour of these two interdependent systems and identify risk components during precipitation events. We apply the model to a watershed during different return periods of precipitation events in Cincinnati, Ohio, USA. The results reveal that the behaviour of some inconspicuous pipes has a significant impact on the sewer-road network system, resulting in a significant decrease in the system performance. Moreover, the interactions between road and sewer networks create multiple microstructures of connected components, which leads to different risks of interdependent systems and road inundations. The modelling results provide target areas for mitigation projects to reduce rainstorm-induced risks. [ABSTRACT FROM AUTHOR]

A sewer system is a principal element of infrastructure in modern cities, accounting for massive amounts of public investments. Corrosion of manholes in the sewer system is a global issue, and millions of dollars are being spent on the maintenance, restoration, and replacement of deteriorated sewer networks. Concrete manholes in the sewer system are deteriorating due to the attack of sulfuric acid produced by microorganisms in a process termed microbial induced concrete corrosion (MICC), which reduces the lifespan of concrete sewer elements. The objective of this paper is to investigate the correlation between the gas- and liquid-phase sewer environmental factors and hydrogen sulfide concentration in the gas phase. The production, emission, and build-up of hydrogen sulfide gas in manholes is identified as a major cause of MICC in manhole shafts. The field study was conducted in more than 200 manholes in the City of Arlington (Texas, US). The data was collected every minute for 48 h to understand the trends of liquid- and gas-phase parameters such as hydrogen sulfide (H2S concentration), liquid and gas temperature, pH, DO, and relative humidity. The study also examines how gas-phase H2S concentrations vary with season; manhole design, including manholes' depth, slope, and presence of drop; and sewer flow conditions such as velocity and turbulence. Although no strong linear correlation was found between liquid-/gas-phase parameters, the manhole categories were found to play a significant role in H2S generation. The manholes with hydraulic jump generated the highest average H2S concentrations, followed by manholes with drops. High turbulence zones were observed in manholes of both categories, leading to H2S stripping from liquid to gas phase. The highest H2S concentration was recorded in summer, suggesting that higher liquid temperature resulted in increased bacterial activity, which generated greater liquid-phase sulfide. Greater Henry's law constants in summer, due to high temperatures, would have favored transfer of liquid-phase sulfide to the gas phase. [ABSTRACT FROM AUTHOR]

The Storm Water Management Model (SWMM) is a reliable software program for simulating stormwater runoff in combined drainage facilities. However, it faces challenges in efficiency, especially when executing real-time forecasting. This research explores an alternative machine learning (ML) approach to predict water levels in sewer and street drainage systems utilizing SWMM data for model training. The goal is to construct a hybrid ML model for urban flooding prediction, considering hydrological conditions, geomorphologic properties, and drainage facility features. A robust training method is introduced to deliberate complex flow conditions. The suggested approach achieves favourable performance in predictive accuracy and computational efficiency. Findings include: (1) similarity between ML and SWMM flooding depth on street nodes increases from 62.3% to 96.2% with the proposed training; (2) the proposed model is about 50 times faster than SWMM in urban flood simulations; (3) reliable predictions from the ML model are demonstrated through four accuracy metrics. [ABSTRACT FROM AUTHOR]

During the discharge of floodwater from a hydropower station, a significant number of water droplets in motion are created in the downstream space. These droplets vary in size and velocity, causing challenges in determining the particle size and velocity distribution of the flood discharge atomized droplets. Currently, the particle-size distribution and velocity distribution of atomized droplets are considered to be independent, and the gamma function is used to describe the particle-size distribution and velocity distribution of droplets separately. However, a joint distribution of atomized droplet size and velocity is lacking. This paper uses the basic theory of maximum entropy to study the combined distribution of droplet size and velocity in the atomized flow caused by jet overflow. The present model was in a good agreement with experimental data, providing a method for the theoretical study of droplet size and velocity distribution in flood discharge atomization. [ABSTRACT FROM AUTHOR]

Risk assessment lies at the core of decision making practices, relying on the likelihood of failure incidents and their consequential impacts integrated through a set of decision rules. The incorporation of fuzzy inference systems (FIS) into risk assessment has been proven to elevate the management and sustainability of infrastructures by reducing uncertainties in decision making and mimicking human decisions. Its parameters, primarily the fuzzy sets, are conventionally defined heuristically to align with the visions and objectives of decision makers or through clustering methods if data are available. However, utilizing these methods is insufficient for the comprehensive adoption or finetuning of input-output relationships, and it does not adequately address the incorporation of future changes in decision makers' opinions due to its inability to self train. To overcome this challenge, a Mamdani-based neurofuzzy system is proposed and modified for best practice in risk assessment, and a framework is developed for compiling the required training data set. Additionally, modifications in the training process include adding Lagrange equality constraints to the objective function and testing different optimizers to maintain the fuzzy logic and reduce the computational cost, respectively. The validation of the model's ability to learn the knowledge base and parameters of fuzzy set membership functions was conducted through training simulation on generic data developed from a predefined knowledge base, as explained in a case study. The data serve as an idealization or simulation of any risk data set that can be generated using the proposed framework. The model has confirmed its ability to learn the knowledge base from which the data are generated and the corresponding parameters of membership functions toward the comprehensive adoption of input-output relationships. This emphasizes the model's capability to learn the knowledge base from any risk data set developed using the proposed framework. Also, results have shown that the added constraints control the training process efficiently by maintaining proper interactions among fuzzy sets membership functions satisfying fuzzy logic; additionally, the Adam (adaptive momentum estimation) optimizer has reduced the training computational cost by more than 99%. Finally, to explain and validate the flexibility of the neurofuzzy model in risk assessment in adopting changes in the FIS hyperparameters and rules, the model was retrained after inducing three independent possible changes to the decision rules and the fuzzy sets. The model has proved its ability to grasp diverse decision maker requirements, giving more flexibility and broader implementation of FIS in risk assessment. [ABSTRACT FROM AUTHOR]

Over the recent years, ever-increasing population growth and higher wastewater production has been a challenge for decentralized wastewater treatment plants (WWTPs). In addition, sludge treatment due to high cost for equipment and place make authorities to find a sustainable approach in both of economical and technical perspectives. One of the proposed solutions is transferring the sludge produced from decentralized WWTP to centralized WWTP. However, the appropriate proportional ratio of raw sludge to raw sewage is a challenge, otherwise, it make anaerobic conditions and sewage rotting along the sewer network based on permissible limit of dihydrogen sulfide (H2S) gas (5 ppm). In the present study, seven reactors with different ratios of sludge to raw sewage (0, 15, 20, 25, 50, 75, 100) were used to stimulate the feasibility of transferring Shahrake Gharb WWTP sludge along the wastewater transfer pipe to the centralized sewage treatment south Tehran WWTP plant in Tehran, Iran. The septic situation and H2S emission of different reactors within 7 h (Time to reach the compound in the south treatment plant) was analyzed by gas meter. The results indicated that the optimum ratio of sludge to raw sewage was 15% without H2S production during 7 h. In addition, due to the high volume of sludge produced by the Shahrake Gharb WWTP, the optimal ratio of lime to total solids (TS) in sludge (gr/gr) (0.6) increased the sludge loading rate from 15 to 30% without any H2S emission during the stimulation study period. Therefore, the lime stabilization and transfer of sludge from a decentralized WWTP to a centralized WWTP is a feasible way to manage the sludge and enhance the treatment capacity in local WWTP. [ABSTRACT FROM AUTHOR]

Risk analysis (including resilience analysis) of infrastructure requires models that describe the connection of components and subsequent flow dynamics. However, the detailed information needed to define these models may not be available, especially for small‐scale infrastructure that connect to every building. In this paper, we generate location‐specific small‐scale networks using detailed data that should always be available. We propose a general framework where we generate the network topology, we estimate the resource demand at each building, and we design the network components to meet the demands. This general framework is applicable to all types of infrastructure, but many procedures are specific to the type of network being generated. This paper develops the necessary procedures to generate sewer networks and illustrates the usage for an example network in a small study area in Seaside, Oregon. The proposed sewer network generator produces realistic sewer networks as compared to the real network of Seaside. [ABSTRACT FROM AUTHOR]

Sewer biofilms are likely to constitute hotspots for selecting and accumulating antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study aimed to optimize culture conditions to obtain in vitro biofilms, mimicking the biofilm collected in sewers, to study the impact of fluoroquinolones (FQs) on sewer biofilm microbiota. Biofilms were grown on coupons in CDC Biofilm Reactors®, continuously fed with nutrients and inoculum (1/100 diluted wastewater). Different culture conditions were tested: (i) initial inoculum: diluted wastewater with or without sewer biofilm, (ii) coupon material: concrete vs. polycarbonate, and (iii) time of culture: 7 versus 14days. This study found that the biomass was highest when in vitro biofilms were formed on concrete coupons. The biofilm taxonomic diversity was not affected by adding sewer biofilm to the initial inoculum nor by the coupon material. Pseudomonadales, Burkholderiales and Enterobacterales dominated in the sewer biofilm composition, whereas in vitro biofilms were mainly composed of Enterobacterales. The relative abundance of qnrA, B, D and S genes was higher in in vitro biofilms than sewer biofilm. The resistome of sewer biofilm showed the highest Shannon diversity index compared to wastewater and in vitro biofilms. A PCoA analysis showed differentiation of samples according to the nature of the sample, and a Procrustes analysis showed that the ARG changes observed were linked to changes in the microbial community. The following growing conditions were selected for in vitro biofilms: concrete coupons, initial inoculation with sewer biofilm, and a culture duration of 14days. Then, biofilms were established under high and low concentrations of FQs to validate our in vitro biofilm model. Fluoroquinolone exposure had no significant impact on the abundance of qnr genes, but high concentration exposure increased the proportion of mutations in gyrA (codons S83L and D87N) and parC (codon S80I). In conclusion, this study allowed the determination of the culture conditions to develop an in vitro model of sewer biofilm; and was successfully used to investigate the impact of FQs on sewer microbiota. In the future, this setup could be used to clarify the role of sewer biofilms in disseminating resistance to FQs in the environment. [ABSTRACT FROM AUTHOR]

The accumulation of fat, oil, and grease (FOG) deposits in sanitary sewer systems is a global issue responsible for billions of dollars in annual maintenance costs, environmental impact, and public health concerns. Laboratory and data-driven studies have explored the physical and chemical characteristics of FOG deposits, formation kinetics, and factors influencing their accumulation in sewer networks, such as pipe sags, pipe age, and pipe material. However, a scalable modeling platform capable of incorporating FOG kinetics and the key variables driving accumulation is not currently available. This study introduces a new platform for modeling the formation and attachment of FOG deposits in sewer systems, the FOG Sewer Waste Management System (FOG-SWMS). FOG-SWMS was utilized to quantify the impact of pipe sags, pipe age and roughness, and pipe material on the accumulation of FOG deposits in sewer lines. Results indicate that under typical sewer conditions, pipe sags and pipe age may increase the accumulation of FOG deposit mass by as much as approximately 23% and 150%, respectively. Surface pH≥8 , as a proxy for cementitious pipe materials, also resulted in more than a 172% increase in FOG deposit mass accumulation. These results confirm data from previous laboratory studies and machine learning algorithms, and also provide a mechanistic explanation of formation processes. Two full-scale sewer network case studies, Study Area 1 (SA1) and Study Area 2 (SA2), were analyzed using FOG-SWMS, to evaluate the predictive capability of the model to identify FOG deposit accumulation zones. FOG-SWMS successfully predicted approximately 85% and 73% of known accumulation zones in SA1 and SA2, respectively. Significant changes in the spatial and temporal distribution of FOG deposits in response to new commercial and residential development also were demonstrated with the model. Fat, oil, and grease deposits are solid masses that form in sanitary sewer lines and create a variety of issues for municipalities. They are primarily the result of discharged food waste residuals into sewers, which reacts with typical wastewater components to form a solid that can block sewer lines and cause overflow of wastewater. These impacts are common, and equate to an incredible amount of time and money spent on sewer repairs and maintenance. This study introduces a new computer-based model that allows researchers to visualize the formation of FOG deposits in sewer line segments. The model is not limited to specialized researchers; it also is intended to be used by engineers and pretreatment coordinators who may be concerned with the accumulation of FOG deposits in sewer line engineering structures. The main goals of this study were (1) to provide the sewer line workforce with a tool for predicting the accumulation of FOG deposits in sewer networks, especially when there are changes in commercial establishments; (2) to serve as a platform for integrating modern sewer inspection data and sensor deployment studies that are becoming more popular; and (3) to incorporate future advancements in machine learning and AI algorithms. [ABSTRACT FROM AUTHOR]

Motivated by the implementation of a SARS-Cov-2 sewer surveillance system in Chile during the COVID-19 pandemic, we propose a set of mathematical and algorithmic tools that aim to identify the location of an outbreak under uncertainty in the network structure. Given an upper bound on the number of samples we can take on any given day, our framework allows us to detect an unknown infected node by adaptively sampling different network nodes on different days. Crucially, despite the uncertainty of the network, the method allows univocal detection of the infected node, albeit at an extra cost in time. This framework relies on a specific and well-chosen strategy that defines new nodes to test sequentially, with a heuristic that balances the granularity of the information obtained from the samples. We extensively tested our model in real and synthetic networks, showing that the uncertainty of the underlying graph only incurs a limited increase in the number of iterations, indicating that the methodology is applicable in practice. [ABSTRACT FROM AUTHOR]

Improper disposal of wipes results in significant sewer blockages, especially during the COVID-19 pandemic. However, the formation and growth of wipe blockages and their backwater effect in sewers have not been studied. This study employed a vertical rod to simulate sewer obstructions such as tree root intrusion in sewers. Stochastic interactions among wipes, turbulent flow, and the obstruction were experimentally studied in a circular pipe (diameter D = 25 cm), with systematic variations in flow Froude number (Fr), wipe length (L), flow depth (H), submerged rod length (hrod), and rod diameter (drod). It was found that the mean area ratio of wipes (ratio of projected area in water to original surface area of the wipe) ranged from 0.14 to 0.30, indicating the distorted shapes in water. The entrapment probability P (ratio of entrapped to released wipes) for a single wipe was closely correlated with Fr, H/D, L/H, drod/H, and hrod/H, with a maximum value of 0.90. With the increase in the number of wipes released, the influence of the obstruction on wipe accumulation processes became negligible. New equations were developed for characterizing entrapment probability, blockage length, and backwater rise, which can be used to predict the development of wipe blockages and sewage levels. Based on the research findings, policy and management strategies were proposed for wipe blockage reduction in sewers. [ABSTRACT FROM AUTHOR]

Optimization of the spatial distribution of green infrastructures (GIs) was performed for a combined sewer system located in the Province of Quebec, Canada, using a simulation-optimization tool with the aim of reducing seasonal combined sewer overflows (CSOs). The performance of four CSOs control alternatives involving the individual and integrated implementation of GIs with storage tanks and real time control (RTC) of the sewer was evaluated for a nine-year simulation period of historical rainfall data and for 20%-increased rainfall data (representative of potential climate change impact). The integration of GIs with RTC of the sewer (with or without storage tanks) lowered the total CSO volume by 95% to 99% under historical rainfall data and by 93% to 96% under increased rainfall intensities when compared to the reference scenario. Adapting GI's number and location for optimal CSO control rather than according to space availability criteria reduced CSO frequency but had only a slight impact on CSO volume reduction. [ABSTRACT FROM AUTHOR]

Sewer systems are a component of city infrastructure that requires large investment in construction and operation. Metaheuristic optimization methods have been used to solve sewer optimization problems. The aim of this study is to investigate the effects of network size on metaheuristic optimization algorithms. Cuckoo Search (CS) and four versions of Grey Wolf Optimization (GWO) were utilized for the hydraulic optimization of sewer networks. The purpose of using different algorithms is to investigate whether the results obtained differ depending on the algorithm. In addition, to eliminate the parameter effect, the relevant algorithms were run with different parameters, such as population size. These algorithms were performed on three different-sized networks, namely small-sized, medium-sized, and large-sized networks. Friedman and Wilcoxon tests were utilized to statistically analyze the results. The results were also evaluated in terms of the optimality gap criterion. According to the results based on the optimality gap, the performance of each algorithm decreases as the network size increases. [ABSTRACT FROM AUTHOR]

As a basic infrastructure, sewers play an important role in the innards of every city and town to remove unsanitary water from all kinds of livable and functional spaces. Sewer pipe failures (SPFs) are unwanted and unsafe in many ways, as the disturbance that they cause is undeniable. Sewer pipes meet manholes frequently, unlike water distribution systems, as in sewers, water movement is due to gravity and manholes are needed in every intersection as well as through pipe length. Many studies have been focused on sewer pipe failures and so on, but few investigations have been done to show the effect of manhole proximity on pipe failure. Predicting and localizing the sewer pipe failures is affected by different parameters of sewer pipe properties, such as material, age, slope, and depth of the sewer pipes. This study investigates the applicability of a support vector machine (SVM), a supervised machine learning (ML) algorithm, for the development of a prediction model to predict sewer pipe failures and the effects of manhole proximity. The results show that SVM with an accuracy of 84% can properly approximate the manhole effects on sewer pipe failures. [ABSTRACT FROM AUTHOR]

In many smart systems, such as cloud computing, networked control, manufacturing, and telecommunication, the effects of time delays are unavoidable. Saturation nonlinearity is common in many smart systems (e.g. electric systems with limited actuator power supplies, mechanical systems with position and speed constraints, fixed-point digital filters, etc.). Therefore, the study of stability of discrete-time systems (DTSs) with time delay and saturation is of high importance in practice. The global asymptotic stability (GAS) problem of such systems is investigated in this paper. The saturation nonlinearity is constrained by a convex hull with a free matrix whose infinity norm is smaller than or equal to unity. A new Lyapunov-based GAS criterion for DTSs with time-varying delay and state saturation is established. The GAS problem for DTSs with constant delay and saturation is also discussed. The obtained results can be used to ensure the absence of overflow oscillations in the considered system. In comparison to several existing criteria, the approach yields improved stability results. An example is provided to demonstrate the importance of the presented results. [ABSTRACT FROM AUTHOR]

Societal pressure to reduce greenhouse gas emissions has compelled organisations to actively manage their carbon footprint. This paper investigates calculating the carbon footprint of the company Prague Water Supply and Sewerage, which serves as an example of a water management organisation in Central Europe. The specificity of research lies in consideration of characteristics related to the energy balance, water sources, climate, the number of consumers, and the political situation, which are most characteristic of the chosen location but may differ from the characteristics of organisations in other parts of the world. A comprehensive assessment of the carbon footprint of the investigated organisation is based on the life cycle assessment methodology. The results of this study show three main directions that significantly impact the carbon footprint: process emissions, purchased energy and purchased services. The recommendations based on the obtained results include the replacement of outdated equipment with more modern and energy-efficient alternatives, transitioning to renewable energy sources, implementation of energy recovery technologies, investigation of alternative processing methods that use fewer chemicals and energy, and giving preference to suppliers of goods and services with good environmental characteristics. [ABSTRACT FROM AUTHOR]

Increasingly, collective actors in Europe, such as in the Netherlands and Italy, turn to litigation as the preferred strategy to attain their goals. Both at the national level and at the European level, civil society organisations (CSOs) are active in high‐profile cases, for example, in the field of asylum law. These CSOs operate in a different national political and legal system but do have similar European‐level opportunities. However, the extent to which European Union (EU) law is mobilised differs per CSO. This begs the following key question: Why do some CSOs mobilise EU law more frequently than others? Using empirical data, this article attempts to uncover what factors are relevant for four CSOs from Italy and the Netherlands whether to mobilise EU law or not. Most importantly, the article concludes that the framing of EU legal opportunities by the CSOs is considered to be relevant in (non‐)mobilisation of EU law. [ABSTRACT FROM AUTHOR]

The uniform flow in a horseshoe-shaped tunnel is often encountered in many practical cases. This pipe can be used for water drainage in sewerage and construction. For the purpose of designing this type of channel with the presumption of uniform flow, it is necessary to refer to Chezy and Manning relationships. In general, Chezy's and Manning's coefficients are given as data of the problem and are mostly considered constants regardless of the normal flow depth. This is an approximation of the fact that the flow resistance should vary with depth or hydraulic radius. In this study, the pipe is designed with a variable flow resistance coefficient, depending on the fill rate of the pipe. The Chezy coefficient is no longer data of the problem but a variable to be determined. The determination of Chezy's coefficient is made possible by the rough model method (RMM). The proposed sizing method is valid in the entire turbulent flow domain, encompassing smooth, transitional, and rough turbulent flow regimes in a wide practical range. [ABSTRACT FROM AUTHOR]

In the field of defect detection in sewers, some researches focus on high accuracy. However, it is challenging for portable on-site devices to provide high performance. This paper proposes a lightweight sewer defect detection model, You Only Look Once (YOLO) v5-Sewer. Firstly, the backbone network of YOLOv5s is replaced with a stacked MobileNetV3 block. Secondly, the C3 module of the neck of YOLOv5s is improved with a C3-Faster module. Thirdly, to compensate for the accuracy loss due to the lightweight network, a channel attention (CA) and convolutional block attention module (CBAM) are added to the proposed method. Finally, the Efficient Intersection over Union (EIOU) is adopted as the localization loss function. Experimental validation on the dataset shows that YOLOv5-Sewer achieves a 1.5% reduction in mean Average Precision (mAP) while reducing floating-point operations by 68%, the number of parameters by 55%, and the model size by 54%, compared to the YOLOv5s model. The detection speed reaches 112 frames per second (FPS) with the GPU (RTX 3070Ti). This model successfully implements a lightweight design while maintaining the detection accuracy, enhancing its functionality on low-performance devices. [ABSTRACT FROM AUTHOR]

Flooding in urban areas is expected to increase its magnitude and frequency in the future. Therefore, there is a strong need to better model sewer–surface flow interactions. Existing numerical methods are commonly based on simplified representations of sewer/surface mass exchange, and mainly validated in steady flow conditions. Current methodologies describing the propagation of transient conditions/waves through interaction nodes are simplified, rely on empirical coefficients and/or lack detailed validation. In this paper, an integrated numerical approach for modelling the propagation of water waves through interaction nodes (e.g., manholes) is presented. In this solution, the shallow water equations are used to simulate the free‐surface propagation inside the sewer network, and an ordinary differential equation is employed for modelling flow regimes through pipes and manholes. The model proposed is validated against the well‐known STAR‐CD modelling software for a number of test cases. Finally, further validation is performed against experimental data describing the evolution of water depth around a manhole in unsteady surcharging conditions. [ABSTRACT FROM AUTHOR]

This study employs a temporal fusion transformer (TFT) for predicting overflow from sewer manholes during heavy rainfall events. The TFT utilised is capable of forecasting overflow hydrographs at the manhole level and was tested on a sewer network with 975 manholes. As part of the investigations, the TFT was compared to other deep learning architectures to evaluate its predictive performance. In addition to precipitation measurements and forecasts, the issue of how the additional consideration of measurements in the sewer network as model inputs impacts forecast accuracy was investigated. A varying number of sensors and different measurement signals were compared. The results indicate high performance for the TFT compared to other model architectures like a long short-term memory (LSTM) network or a dual-stage attention-based recurrent neural network (DA-RNN). Additionally, results suggest that considering a single measuring point at the outlet of the sewer network instead of an entire measuring network yields better forecasts. One possible explanation is the high correlation between measurements, which increases model and training complexity without adding much value. [ABSTRACT FROM AUTHOR]

South Carolina's Beaufort‐Jasper Water and Sewer Authority optimized its wastewater systems using Partnership for Clean Water goals. [ABSTRACT FROM AUTHOR]

Sewer systems play vital roles in wastewater treatment facilities, and the microbial communities contribute significantly to the transformation of domestic wastewater. Therefore, this study conducted a 180-day experiment on a sewer system and utilized the high-throughput sequencing technology to characterize the microbial communities. Additionally, community assembly analysis was performed to understand the early-stage dynamics within the sewer system. The results demonstrated that the overall diversity of microbial communities exhibited fluctuations as the system progressed. The dominant phyla observed were Chloroflexi, Bacteroidetes, Firmicutes, and Proteobacteria, accounting for over 85.4% of the total relative abundances. At the genus level, bacteria associated with fermentation displayed a high relative abundance, particularly during days 75 to 180. A random-forest machine-learning model identified a group of microbes that confirmed the substantial contribution of fermentation. During the process of fermentation, microorganisms predominantly utilized propionate formation as the main pathway for acidogenesis, followed by acetate and butyrate formation. In terms of nitrogen and sulfur cycles, dissimilatory nitrate reduction and assimilatory sulfate reduction played significant roles. Furthermore, stochastic ecological processes had a dominant effect during the experiment. Dispersal limitation primarily governed the assembly process almost the entire experimental period, indicating the strong adaptability and metabolic plasticity of microorganisms in response to environmental variations. This experiment provides valuable insights into the metabolic mechanisms and microbial assembly associated with sewer systems. [ABSTRACT FROM AUTHOR]

During wet weather events, combined sewer overflows (CSOs) transfer large amount of particulate matter and associated pollutants into surrounding water bodies, thereby deteriorating the recipients' ecological health. Resuspension of sewer sediments during these events contributes significantly to pollution level of these discharges. However, how much this in-sewer process contributes to CSOs' quality regarding microplastic (MP) pollution is little known. Therefore, an investigation on sewer deposits inside the Parisian combined sewer network was carried out. The study found high MP concentrations stored in this matrix, ranging from 5 × 103 to 178 × 103 particle/kg dry weight. Polymer composition is similar to what found in raw wastewater, containing a high proportion of polyethylene and polypropylene. Thus, the results indicated the persistence of MPs in sewer network during transport during dry weather periods to treatment facilities. Once resuspension of sewer deposits happens, MPs can be released into water flow and get discharged along with CSOs. This highlights another potential pathway of MPs into freshwater environment. [ABSTRACT FROM AUTHOR]

This paper investigates the overflow oscillation elimination problem in the fixed-point two-dimensional (2D) digital filter (DF) based on Roesser model subjected to two's complement overflow (TCO) nonlinearities. By utilizing the system information and behavior of TCO nonlinearities more effectively, a new global asymptotic stability (GAS) criterion for 2D DFs is presented. A comparison of the obtained criterion with existing criteria is made with the help of examples. [ABSTRACT FROM AUTHOR]

Deep sound speed structure in the western Irminger Sea is found to be highly dynamic in comparison to the adiabatic (uniform) sound speed gradient underpinning data assimilation and modeling efforts around the globe. A beamed source parabolic equation model is used to illustrate how the resulting non-uniform sound speed structure at 1 to 1.5 km in depth and sound speed inversion near the seafloor produce observable effects on acoustic signals between a shallow source and shallow vertical line array at convergence zone ranges. Beamforming analysis shows that a uniform sound speed gradient leads to "ideal" interference patterns that do not capture or represent modeled convergence zone properties, such as location, strength, and sharpness. Overall findings suggest that in situ information about sound speed below 1 km is necessary for low frequency, long-range propagation studies, particularly in areas of complex thermohaline circulation. [ABSTRACT FROM AUTHOR]