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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]

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]

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]

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]

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 presents a flexible framework that aims at estimating the risk of structural failure in sewer pipes by utilizing limited or imperfect data. To this end, classical risk analysis is enhanced by incorporating fuzzy logic and multi-criteria decision making. To account for the multi-dimensionality of collapse risk at the pipe level as a decision parameter, its distinct impacts on the environment, traffic and road condition, and quality of life are taken into account. The proposed method is applied to the sewer network of Tehran, the capital of Iran. Results show how the integration of different risk indexes can influence the criticality of pipelines for the selection of rehabilitation activities. While using the first individual risk index, only considering the risk posed to the natural environment by a collapsing pipe in terms of contamination, approximately half of the pipe lengths are classified as extremely critical by the clustering algorithm. However, when the integrated risk is calculated, this cluster encompasses only approximately 30% of the total pipe length. With a database that contains various levels of uncertainty (from 10 to 60%), the predictive reproducibility for the exact same risk cluster is above 20% and above 50% for the same or only marginally better or worse. Furthermore, pipelines that are predicted to have a better risk class than the situation without considering uncertainty, thereby underestimating the likelihood of failures or consequences, are below 15%, showing a measure of quite good robustness. Considering the budget constraints of utilities, the proposed method can be applied to any urban, aiding in the identification of high-risk sections. Nevertheless, incorporating physical validation might be beneficial for further improving the analysis. [ABSTRACT FROM AUTHOR]

Groundwater pollution poses a significant threat globally, particularly in developing countries where inadequate sanitation facilities contribute to growing concerns about contamination from sewer leaks. Hence, the objective of this study is to present a comprehensive review, offering insights into diverse aspects of sewer leaks and their impacts on the urban groundwater system. This includes an exploration of leak sources, methods for leak detection, quantification approaches, analysis of contaminants in sewage along with their health effects, and strategies for mitigating both sewer leaks and groundwater contamination. This review addresses various factors leading to sewer infrastructure damage, emphasizing its importance in effective maintenance strategies. In this review, a range of contaminants released from sewer leaks were outlined, ranges from emerging contaminants to heavy metals that poses risk to the human health and environment. Further it evaluates various methods for detecting sewer leaks, emphasizing advancements in water quality analysis, visual, electromagnetic, and acoustics techniques. This research assesses diverse techniques for quantifying sewage leaks, including mass balance and wastewater balance and concludes pinpointing specific leak hotspots remains challenging. Furthermore, an appraisal of mitigation measures was also conducted, determining that rehabilitation serves as a more effective approach to stop leaks at their source. This paper delves into groundwater treatment methods, highlighting the difficulties in achieving optimal water quality and reveals that technologies such as Permeable Reactive Barrier and advanced oxidation processes exhibit potential in effectively removing trace-level pollutants. Overall, the review underscores the importance of understanding, detecting, and mitigating sewer leakage for the health and sustainability of groundwater systems. [ABSTRACT FROM AUTHOR]

The effects of longitudinal inclined plates and perforated inlet baffle on the settling efficiency and the overall hydrodynamics of a rectangular sedimentation tank are investigated using computational fluid dynamics. Five new cases of modified geometry have been thoroughly analyzed for this study. To simulate the multiphase flow, the Euler–Lagrange method is adopted by using the Discrete Phase Model. Experimentally obtained particle size distribution data of a potable water treatment plant and an industrial wastewater treatment are used to examine the effectiveness of the modifications in improving the settling efficiency. The longitudinal inclined plates are found to be highly effective in increasing the settling efficiency by increasing the settleable area, while the perforated baffle is found to be useful in dissipating the kinetic energy from the influent and helps in achieving plug-flow conditions in the sedimentation tank. It was also found that the controlled recirculation currents may be beneficial for settling fine particles. [ABSTRACT FROM AUTHOR]

How did Civil Society Organizations (CSOs) globally address the needs caused by the COVID-19 pandemic? In this study, we examine the roles CSOs played during the first 18 months of the pandemic, their main challenges, and how the pandemic changed CSOs' roles in society across 39 countries and economies. Using inductive thematic analysis analyzing responses from global philanthropy experts in two consecutive studies (2020 and 2021), we find that CSOs played fourteen roles, of which we discuss the six most mentioned: providing social assistance; responding to health care needs; coordinating and collaborating with government and business; mobilizing funds to address societal needs; raising awareness and combating misinformation; and advocating. Challenges for CSOs included reduced revenue and difficulty reaching beneficiaries. We found these challenges led to innovative ways of operating and new arrangements between civil societies and governments, which may have opened opportunities for a more active role of CSOs. [ABSTRACT FROM AUTHOR]

Premature failure of two upward-inclined underground pipes carrying sewage caused sinkhole formation in a busy urban road. Metallurgical failure analysis revealed that the pipes were made of ductile cast iron. External and internal coatings were appropriate to protect the pipes from external soil and internal sewage slurry corrosion. Partial filling of sewage slurry during the pumping recess allowed turbulent flow in the empty section during pumping, and the impact of turbulence eroded the internal coating, i.e., mortar lining, introduced erosion–corrosion and progressively reduced the pipe wall thickness in the upper half of the pipes resulting to weakening. Intermittent turbulence led to some localized corrosion fatigue-induced fracture in the weakened pipe wall. Erosion–corrosion with the assistance of corrosion fatigue led to the premature failure of the ductile cast iron pipes. [ABSTRACT FROM AUTHOR]

Leaky urban drainage networks (UDNs) exfiltrating wastewater can contaminate aquifers. Detailed knowledge on spatiotemporal distributions of water-dissolved, sewer-borne contaminants in groundwater is essential to protect urban aquifers and to optimize monitoring systems. We evaluated the effect of UDN layouts on the spreading of sewer-borne contaminants in groundwater using a parsimonious approach. Due to the UDN's long-term leakage behavior and the existence of non-degradable sewer-borne contaminants (equivalent to a conservative and constant contaminant source), we employed a concept of horizontal line sources to mimic the UDN layout. This does not require the consideration of bio-degradation processes or temporal delay and effectively bypasses the vadose zone, thus reducing computational requirements associated with a full simulation of leakages. We used a set of synthetic leakage scenarios which were generated using fractals and are based on a real-world UDN layout. We investigated the effects of typical leakage rates, varying groundwater flow directions, and UDN's layouts on the shape of the contaminant plume, disregarding the resulted concentration. Leakage rates showed minimal effects on the total covered plume area, whereas 89% of the variance of the plume's geometry is explained by both the UDN's layout (e.g., length and level of complexity) and groundwater flow direction. We demonstrated the potential of applying this approach to identify possible locations of groundwater observation wells using a real UDN layout. This straightforward and parsimonious method can serve as an initial step to strategically identify optimal monitoring systems locations within urban aquifers, and to improve sewer asset management at city scale. [ABSTRACT FROM AUTHOR]

While the main focus of numerous engineering-geological investigations is to determine load-bearing capacity and settlement in engineering structures, this article aims to point at the specificity of sewer system engineering-geological investigations, which focuses on workability of soils and rocks. The study deals with workability class assessment of seven different sewer system localities. The significance of this research lies in the mutual comparison of workability class assessment of these seven localities in terms of two different workability standards. Each of the standards represents an independent model of assessment and classification of workability. The first standard (CSN 73 1001) classifies soils and rocks into seven workability classes, while the second (EN ISO 14688) comprises only three workability classes. Each of the approaches has its advantages and disadvantages. In comparison to the first one, the second standard permits faster and easier classification of rocks, but may be less fair to investors or developers when considering the real engineering-geological conditions and costs of implementation. Rocks were newly classified into three (easy, medium and difficult) categories of earthwork realization difficulty. In the study, 33 layers were classified in the category of easy realization of earthworks, 8 layers in the category of a medium degree of earthwork realization difficulty, and two layers in the category of a difficult realization of earthworks. [ABSTRACT FROM AUTHOR]

This research uses the concept of 'urban scenes' to explore and characterise the economy of the city of Makhanda (Grahamstown). It is argued that this framework can create a thorough situational analysis on which to plan for locally-appropriate Local Economic Development (LED). It does this through characterising a local economic context that situates economic activity within a framework that acknowledges the role and interactions of consumers, culture, clustered amenities and economic activities, and urban place. It thus adds to traditional situational analyses by focusing on the urbanisms, activities, and character of the city—making these factors indivisible from the local economy. The framework reveals that two prominent scenes exist within Makhanda: the Education and Tourism Scenes. Education institutions like top public and private schools and Rhodes University are located within the city, and a tourism product exists in the form of creativity and the arts, festivals, edutourism, heritage, and wildlife safaris and hunting. These scenes bring significant money into the local economy through tourism and temporary education-led migration. They are both, however, under significant threat from a dysfunctional local municipality that has consistently failed in its mandate to support the local economy, engage with local stakeholders, and create an enabling environment for business. Intermittent and unreliable water supply, sewerage spills, and the deterioration of existing infrastructure are just some of the issues faced within the city. Any successful LED programme needs to tackle this issue and others to succeed. In addition to creating an enabling economic environment, cooperation within and between stakeholders in the identified scenes needs fostering. The local municipality also needs to create employment and a more inclusive economy to tackle issues of high unemployment and inequality. [ABSTRACT FROM AUTHOR]

Heavy metals are environmental pollutants and carcinogenic for human health if ingested. In developing countries, including Pakistan, untreated sewerage water is one of the major sources of irrigation for vegetable production in the vicinities of urban areas which might be toxic to human health due to heavy metals contamination. The present study was conducted to investigate the uptake of heavy metals by sewage water application and its impact on human health. The experiment consisted of five vegetable crops (Raphanus sativus L, Daucus carota, Brassica rapa, Spinacia oleracea, and Trigonella foenum-graecum L.) and two irrigation sources (clean water irrigation and sewage water irrigation). Each treatment was three time replicated for all five vegetables, and standard agronomic practices were applied. The results demonstrated that shoot and root growth in radish, carrot, turnip, spinach, and fenugreek was enhanced significantly with sewerage water, probably due to enhanced organic matter. However, pithiness was observed in the root of radish under sewerage water treatment. Very high concentrations of Cd, up to 7.08 ppm in turnip roots while up to 5.10 ppm in fenugreek shoot, were observed, and other vegetables also contained higher concentrations of Cd. Zn concentrations in the edible parts of carrot (control (C) = 129.17 ppm, sewerage (S) = 164.10 ppm), radish (C = 173.73 ppm, S = 253.03), turnip (C = 109.77 ppm, S = 149.67 ppm), and fenugreek (C = 131.87 ppm, S = 186.36 ppm) were increased by sewerage water treatment but a decrease in Zn concentration in spinach (C = 262.17 ppm, S = 226.97 ppm) was observed. Fe concentration in edible parts of carrot (C = 888.00 ppm, S = 524.80 ppm), radish (C = 139.69 ppm, S = 123.60 ppm), turnip (C = 195.00 ppm, S = 121.37 ppm), and fenugreek (C = 1054.93 ppm, S = 461.77 ppm) were also decreased by sewerage water treatment while spinach leaves had accumulated higher Fe (C = 1560.33 ppm, S = 1682.67 ppm) in sewerage water treatment. The highest bioaccumulation factor value was 4.17 for Cd in carrots irrigated with sewerage water. The maximum value of bioconcentration factor was 3.11 for Cd in turnip under control, and the highest value of translocation factor was 4.82 in fenugreek irrigated with sewerage water. Daily intake of metals and health risk index (HRI) calculation indicated that HRI for Cd was more than 1, suggesting toxicity in these vegetables while HRI for Fe and Zn is still under safe limit. Correlation analysis among different traits of all vegetables under both treatments revealed valuable information for selecting traits in the next crop breeding programs. It is concluded that untreated sewerage-irrigated vegetables, highly contaminated with Cd, are potentially toxic for human consumption and should be banned in Pakistan. Furthermore, it is suggested that the sewerage water should be treated to eliminate toxic compounds, particularly Cd, before irrigation usage and non-edible/phytoremediation crops might be grown in contaminated soils. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of overflow oscillation elimination in fixed-point two-dimensional (2D) discrete systems represented by Fornasini–Marchesini second local state-space (FMSLSS) model with two's complement overflow (TCO) arithmetic. By utilizing the structural behavior of TCO nonlinearities in greater depth, a new Lyapunov-based criterion for determining the global asymptotic stability (GAS) of the considered system is derived. The criterion can also be applied to evaluate the GAS of 2D FMSLSS model with other commonly used overflow arithmetic (such as saturation, triangular, and zeroing). An example to demonstrate the utility of the criterion is also given. The criterion is compared with the previously reported criteria. [ABSTRACT FROM AUTHOR]

A lack of regular access to clean and safe water and sanitation is a persistent problem in many parts of the world. Most water insecurity studies focus on the world's less-industrialized and lower-income countries, where sanitation and water delivery infrastructure may never have existed. However, many individuals in higher-income countries experience invisible water insecurity, wherein specific households or individuals lack access to sanitation and clean water despite the relative wealth of their country. In the United States, invisible water insecurity tends to manifest as a result of homelessness, a lack of plumbing facilities, and water utility shut-offs. Using a water shut-off dataset from the Detroit Water and Sewerage Department, we investigate the relationship between a suite of demographic variables and the water shut-off rates in different neighborhoods throughout Detroit, Michigan. We find that shut-offs are more common in areas with more Black households that are more impoverished. Our findings indicate that this relationship links to structural disadvantage resulting from a legacy of racism and segregation in the city. [ABSTRACT FROM AUTHOR]

The consumption of pharmaceuticals has rapidly increased on a global scale due to the serious increase in Covid-19, influenza and respiratuar sinsityal virus, which is called "triple epidemic" in the world. The use of non-prescription analgesic and anti-inflammatory drugs (AAIDs), especially paracetamol, is higher compared to pre-pandemic. This increased the AAIDs load discharged to the aqueous media through sewerage treatment plant (STP). Therefore, simple and effective treatment options for removing AAIDs from STP effluents are needed. The aim of the study was to remove AAIDs (paracetamol, acetylsalicylic acid, codeine, diclofenac, ibuprofen, indomethacin, ketoprofen, mefenamic acid, naproxen, and phenylbutazone) from STP effluents by nearly pure natural clay Na-montmorillonite. The Na-montmorillonite taken from the Ordu region in the northern part of Turkey. Surface area of the Na-montmorillonite is 99.58 m2/g and CEC is 92.40 meq/100 g. The removal efficiencies of AAIDs using Na-montmorillonite were between 82 ± 5% (ibuprofen) and 94 ± 4% (naproxen). Paracetamol was used as a model compound in kinetic and isotherm model studies. Freundlich isotherm model and the pseudo second order kinetic model were the best-fit using the obtained experimental data. Film diffusion governed its rate mechanism. The paracetamol adsorption capacity was acquired as 244 mg/g at 120 min contact time at pH 6.5 at 25 °C. With this study, it could be shown that montmorillonite can be used effectively to eliminate paracetamol from STP effluent. Natural clay can be used as a simple, inexpensive and effective adsorbent for removing AAIDs from STP effluents. [ABSTRACT FROM AUTHOR]

Manholes are vital component of the sewerage system; they are often damaged due to concrete corrosion, hydrogen sulphide (H2S) gas released by sewage effluent and vehicular loading. Due to large number of accidents occurred on the road, there is need for supervision of manholes so that it can be replaced when it is about to damage. In this paper, three different manholes were tested according to Indian standard code IS 12592 (2002). At the same time, using electro mechanical impedance (EMI) technique, the damage quantification was done using root mean square deviation (RMSD) for the obtained signature of the manholes with different damage stages. Three PZT sensors were bonded using epoxy, one each on top and bottom of manhole cover and third at the frame of the manhole. It was found that the PZT bonded at bottom captures the damages well than the PZT bonded on the top of cover, but it shows large variation when the crack line passes through the PZT bonded place, the PZT bonded on the frame shows abrupt variations with the damage. Hence, PZT sensor pasted on top of manhole cover was found to be well correlated to the damage stages. The effective structural parameters were extracted using PZT sensor; moreover, for all the three manhole structures, the structural damping was identified for different damage states. A model was developed including all three manholes with more than 95% confidence level for estimating the remaining life of manhole. [ABSTRACT FROM AUTHOR]

Fat, oil, and grease (FOG) deposits, resulting from saponification reaction, have been identified as the primary source of blockage of sewer pipes. This mainly emanates from the adhesion of these deposits on pipe walls, culminating in the sanitary sewer overflows (SSOs). This undesired phenomenon poses several challenges for municipalities, including environmental issues, health-related hazards, and an increase in incurred costs. Unlike the previous literature, the present study, for the first time, attempts to characterize the effect of used cooking oils (a mixture of different oils) as a perceived crux, triggering the genesis of deposits. The experimental results revealed that there exists a host of physical and chemical disparities between fresh oil calcium soaps (FOCSs) and used oil calcium soaps (UOCSs). Notably, when mixed with water, FOCSs produced non-miscible layers, whereas a homogenous, sticky, and viscous solution observed for UOCSs. Fourier transform infrared (FTIR) analysis casts light on the fact that the heating process would greatly influence the oil chemical structure and its resultant calcium soaps. In comparison with calcium chloride, as time elapsed, the optical microscope images illustrated that the calcium sulfate clots formation proceeded at an accelerated rate, delivering particles with larger sizes. Viscosity and adhesion are two prominent distinctions between soaps. In sharp contrast to soap produced from oil with a higher palmitic acid content, it was discerned that the oil containing less palmitic acid generates UOCSs with higher viscosity and adhesion than FOCSs. It can therefore be inferred that the distinct chemical structures driven by high temperature during the cooking process produce soaps with different characteristics as compared with fresh oil. This phenomenon would have a profound impact on the formation of the deposits in sewer lines. [ABSTRACT FROM AUTHOR]

Kalpani River, Pakistan is an important stream that collects more than two third of the untreated domestic, commercial, industrial, and sewerage water, agricultural overflow, and other unwanted effluents of the surrounding area. These effluents have degraded the overall quality of this river water. The current study aims to examine the concentration of selected heavy metal (HM) contamination in Kalpani River sediments. The HMs studied were Pb, Cd, Zn, Ni, Fe, and Cu. Sediment samples were taken from nine selected locations (labeled as P1, P2, P3, ... P9) and tested for HM contamination. The HMs contamination level in the sediment was computed using the contamination factor (CF), pollution load index (PLI), and geo-accumulation index (Igeo). All three indicators revealed that the Kalpani River in Mardan city is polluted with hazardous HMs such as Cd, Pb, and Zn. Pb, Ni, Fe, and Cu CF levels in sediment samples ranged from low (< 1) to moderate (1–3). However, the CF values for Cd and Zn indicated being highly polluted (> 6). The PLI values along the Kalpani River varied considerably and were observed lower upstream (P1 and P2, i.e., 0.821), highest (1.229) at the middle course, and lower (0.897) downstream. The Igeo for the studied HMs ranged from moderately to strongly polluted. The primary anthropogenic sources responsible for HM pollution in the Kalpani River were improper waste dumping, untreated sewage urban and industrial wastewater into the river, and excessive pesticide usage. [ABSTRACT FROM AUTHOR]

Total ammonia (TA) concentrations (NH3 + NH4+) at four locations at the terminal end of the Mississippi River, the largest river on the North American continent, were assembled to examine trends and relationships with point and non-point loadings from 1980 to 2019 and compared to values in 1900 to 1901. TA concentrations were lowest in 1900 to 1901, highest in 1980 and then declined, and then rose slightly in the last 2 decades. Variations in individual measurements and in situ temperature are indirectly related because of the influence temperature has on ammonia solubility and protein degradation rates. Importantly, the average annual concentrations of TA were directly related to both total coliform and fecal coliform densities. The highest measured average annual TA concentrations in the river (15.5 ± 1.5 SE µmol in 1985) were below the currently recommended toxicity thresholds for freshwater aquatic ecosystems. Sewerage loadings are implicated as controlling factors on TA concentrations, not nitrogen stabilizers added to fertilizers to reduce ammonia conversion to nitrate, nor the fertilizer loadings. [ABSTRACT FROM AUTHOR]

The design rainfall intensity and its return period of the combined interceptor sewer is an important factor affecting combined sewer overflow (CSO) occurrence. However, we often use the interceptor ratio (or interceptor multiple, n0) to design the interceptor sewer, and its equivalent design return period is often ignored. In this study, a low return period rainfall formula modeling method was proposed to estimate this return period. First, a new rainfall event separation approach was especially developed, and the minimum interevent time (MIET) was set to time of concentration of the tributary area corresponding to the most downstream interceptor well. Second, a new rainfall intensity sampling algorithm, annual multi—event—maxima (AMEM) sampling algorithm, was put forward. For this sampling algorithm, several maxima of rainfall intensity should be sampled annually, and only one maximum is sampled for each rainfall event. In addition, the empirical frequency values of the above sampled rainfall intensities can be obtained according to the mathematical expectation formula (Weibull formula). After comparison, the lognormal distribution was selected for the theoretical probability density function. Finally, parameters of the low return period rainfall intensity formula were estimated using three-parameter Horner formula and MCMC (Markov Chain Monte Carlo) algorithm. A case study was conducted to demonstrate the proposed method based on the recorded rainfall data from a meteorological station in southwestern China and a combined sewer system. Results revealed that: (1) A MIET determination method was proposed according to independence of CSO events. (2) An annual multi-event-maxima (AMEM) sampling was proposed for collecting samples of the low return period rainfall intensity. (3) For the case study, the best-fit distribution for low return period rainfall intensity was lognormal distribution. (4) Resulted low return period rainfall intensity formula was provided. [ABSTRACT FROM AUTHOR]

Rainfall-derived infiltration and inflow (RDII) is extraneous water in a sanitary sewer system that originates from surface runoff. Most RDII enters sanitary sewer systems through illegal connections or mechanical faults, especially in aged sewer systems. In this study, the physical process of three primary RDII sources: roof downspout, sump pump, and leaky lateral, are investigated using physics-based models. These three sources represent three different flow paths: direct connection of impervious catchments, mixed flow through coarse porous media followed by a direct connection, and percolated flow through compacted soil. Due to the differences in medium and the lengths of flow paths, flow responses of these three RDII sources differ in time and magnitude. In turn, they can be distinctly identified from each other. The typical flow response of each RDII source is represented as an impulse response function (IRF), a flow response to a pre-specified representative rainfall computed using physics-based models. The total RDII flow hydrograph is presented as a combination of these three IRFs. The weighting factors of each IRF are calculated using a genetic algorithm technique in a test sewer basin in a suburb of Chicago, IL. The model results suggest leaky lateral might be the biggest RDII contributor to the system. The model performance was compared with one of the more widely used RDII estimation methods, the Storm Water Management Model RTK method. While the RTK method shows better performance overall, the IRF method provides a unique solution with robust performance. The suggested physics-based approach may shed light on identifying local RDII issues with more detail, facilitating more effective management of a sewer system. [ABSTRACT FROM AUTHOR]

This article provides a state-of-the-art review on the different turbulence and multiphase models for the sedimentation tank studies of both water treatment plant (WTP) and wastewater treatment plant (WWTP) by computational fluid dynamics. A thorough understanding of these models is required to simulate the hydrodynamics of the tanks as accurately as possible without compromising the computational cost. The turbulence models which are mainly used for predicting hydrodynamic behavior are Reynolds averaged Navier–Stokes equations (RANS) and large eddy simulation (LES) models. Due to the low computational requirement for RANS models, they are widely adopted even if their accuracy is comparatively lower. The SST k-ω model is recommended to be used in the studies of sedimentation tanks as this model is intended to represent better low Reynolds number flows. The comparison among various turbulence models and the superiority of LES over the RANS models are described in this paper. Euler-Euler or Euler–Lagrange approaches can be used to describe the dispersed flow of water and particles in the settling tanks. The selection of a multiphase model for simulation depends upon the type of sedimentation tanks and particle concentrations. The various multiphase models for simulating the dispersed flow in the sedimentation tanks are also explained in this article. Mixture and Eulerian models of the Euler-Euler approach are widely used in the study of settling tanks of both WTP and WWTPs. However, the Euler–Lagrange approach is more suitable for sedimentation tanks of WTP since the volume fraction of particles is small. [ABSTRACT FROM AUTHOR]

Rats are abundant and ubiquitous in urban environments. There has been increasing attention to the need for evidence-based, integrated rat management and surveillance approaches because rats can compromise public health and impose economic costs. Yet there are few studies that characterize rat distributions in sewers and there are no studies that incorporate the complexity of sewer networks that encompass multiple sewer lines, all comprised of their own unique characteristics. To address this knowledge gap, this study identifies sewer characteristics that are associated with rat presence in the city of Seattle's urban sewer system. We obtained sewer baiting data from 1752 geotagged manholes to monitor rat presence and constructed generalized additive models to account for spatial autocorrelation. Sewer rats were unevenly distributed across sampled manholes with clusters of higher rat presence at upper elevations, within sanitary pipes, narrower pipes, pipes at a shallower depth, and older pipes. These findings are important because identifying features of urban sewers that promote rat presence may allow municipalities to target areas for rat control activities and sewer maintenance. These findings suggest the need to evaluate additional characteristics of the surface environment and identify the factors driving rat movement within sewers, across the surface, and between the surface and the sewers. [ABSTRACT FROM AUTHOR]

Extraneous water that inflow to the sewage system is basically divided into two streams—accidental water (mainly rainwater) and infiltration water. The aim of the research was to assess the amount of extraneous water inflow to the considered system. Five different quantitative approaches were applied. Three well-known methods were used: the triangle method, the minimum night flow method, and the moving minimum method. The annual balance of water consumption and sewage supply to the wastewater treatment plant were calculated. Also, some analysis of sewage discharge during wet and dry weather was carried out. The study covered data from 6 years from 2014 to 2019. It was established that the main source of extraneous water was infiltration, because three methods which concern both streams (triangle method, minimum night flow, variability in wet and dry weather) confirm the conclusion. Merely the moving minimum method results differ from the others. In this investigation, accidental water (basically rainwater inflow) poses a significantly less share in the total volume of sewage compared to infiltration water. The total amount of extraneous water was estimated as in the range from 38 to 53% of annual sewage supply to wastewater treatment plant, depending on the year. Share of infiltration and accidental water is changing in different methods. Share of infiltration was in a range between 18 and 68%, depending on the year and the method used. Share of accidental water was in a range between 7 and 22%. [ABSTRACT FROM AUTHOR]

The use of chemicals by society has resulted in calls for more effective control of their emissions. Many of these chemicals are poorly characterized because of lacking data on their use, environmental fate and toxicity, as well as lacking detection techniques. These compounds are sometimes referred to as contaminants of emerging concern (CECs). Urban areas are an important source of CECs, where these are typically first collected in sewer systems and then discharged into the environment after being treated in a wastewater treatment plant. A combination of emission estimation techniques and environmental fate models can support the early identification and management of CEC-related environmental problems. However, scientific insight in the processes driving the fate of CECs in sewer systems is limited and scattered. Biotransformation, sorption and ion-trapping can decrease CEC loads, whereas enzymatic deconjugation of conjugated metabolites can increase CEC loads as metabolites are back-transformed into their parent respective compounds. These fate processes need to be considered when estimating CEC emissions. This literature review collates the fragmented knowledge and data on in-sewer fate of CECs to develop practical guidelines for water managers on how to deal with in-sewer fate of CECs and highlights future research needs. It was assessed to what extent empirical data is in-line with text-book knowledge and integrated sewer modelling approaches. Experimental half-lives (n = 277) of 96 organic CECs were collected from literature. The findings of this literature review can be used to support environmental modelling efforts and to optimize monitoring campaigns, including field studies in the context of wastewater-based epidemiology. [ABSTRACT FROM AUTHOR]

In this paper, we address the role of civil society organisations (CSOs) in Italy with regard to the integration of migrants, asylum seekers and refugees (MRAs) in the labour market. The paper analyses the role played by CSOs in practice, looking at the dynamics of demand and offer of services through the perspective of both the CSOs and MRAs. To achieve this, we combine qualitative data from semi-structured interviews to CSO representatives as well as MRAs. Our findings point out that the fragmentation of the policy framework in terms of employment and integration, and an unfavourable legislation (above all, migration law) shape the kind of prevalent activities of CSOs and negatively impact the potential for integration of MRAs in the labour market. In general, much is left to the single CSO to fill in the needs of MRAs beyond minimal provisions established by law, with just asylum seekers and refugees having better opportunities and support. Furthermore, we can also observe how economic migrants generally tend to be less supported. [ABSTRACT FROM AUTHOR]

The hydraulic capacity of a channel is impacted due to sediment deposition in urban drainage and sewer system. As a result, the self-cleansing mechanism is a widely used phenomena in urban drainage and sewer systems. In this context, the prediction of particle Froude number plays an important role in the design of the sewer system. This study investigates the performance of multiple standalone and ensemble machine learning techniques for the prediction of particle Froude number with reference to non-deposition with deposited bed. Five datasets available in the literature comprising of wide ranges of the volumetric sediment concentration ( C v ), dimensional grain size of particles ( D gr ), sediment median size (d), hydraulic radius (R), pipe friction factor (λ ) have been utilized in this study. For standalone techniques, we made use of a decision tree regressor (DecisionTreeRegressor), multilayer perceptron regressor (MLPRegressor), while for ensemble approach extreme gradient boosting regressor (XGBRegressor), extra trees regressor (ExtraTreesRegressor) have been utilized. To evaluate the proposed models, several performance metrics have been used such as correlation coefficient (CC), Nash–Sutcliffe efficiency (NSE), root mean square error (RMSE), and R 2 . Results indicate that ensemble techniques are more accurate as compared to the standalone methods and empirical equations. Among the proposed models, ExtraTreesRegressor provides the highest prediction (CC = 0.978, NSE = 0.957, RMSE = 0.208, and R 2 = 0.957) followed by XGBRegressor, MLPRegressor, and DecisionTreeRegressor for the prediction of particle Froude number. [ABSTRACT FROM AUTHOR]

The impact of a storm water storage tank outflow construction on its required volume is discussed. A dimensioning of the tank by a rational method applied for small sewerage systems is presented. For large systems, subroutines should be developed to take into consideration the construction details of complex storage tanks in the software enabling real time modelling of sewerage systems. Such subroutines can be tested under simple conditions using rational methods of sewerage modelling, including the approach described in the paper. In the example discussed here for two different positions of the sewer delivering to and collecting stormwater out of the tank both the tank required volume and the outflow as a function of time visibly depended on the sewer position. This was proofed for a rectangular chamber storage tank of the same bottom surface area. However, if the bottom surface area and the storage tank height were calculated in such a way to enable the same maximum value of an outflow from the tank for two different positions of the sewer both the tank volume and the outflow as a function of time were proved to be very similar. Concluding the tank volume depends visibly on the construction of outflow, but the height of the tank can be adjusted in such a way to keep the same maximum outflow for different details of the outflow construction. After this adjustment, the volume of the tank was proved to be almost independent of the construction of outflow from the tank. [ABSTRACT FROM AUTHOR]

In most developed countries, such as the USA, the E.U., and East Asia, the importance of public infrastructure asset management has been stressed for a long time. Among the various types of public infrastructure, sewerage systems are one of the most cost-intensive facilities to manage. Sewerage systems are considered highly difficult to manage due to the undetermined level of service needed, different standards of user satisfaction, and the large gap of service understanding between experts and users. To address these issues, this study aims to define the appropriate target level of service improvement by combining consumers' expected level of service and complaint data. In this study, the case of the inland flood management project in South Korea is investigated because of the global trend of increasing flood damage. The complaint data represent the frequency of flood damage in the area. Using the contingent valuation method, we found that people want to use 25% of their current monthly sewage bill on the management project. In addition, the results of this study demonstrate that people prefer to deal with the problems caused by old service infrastructure when it can be handled at a lower cost during early stages. [ABSTRACT FROM AUTHOR]

Solving urban wastewater management problems requires knowledge of wastewater composition and variability. In the case of combined sewerage, this applies to both dry and wet weather. Wastewater composition is changing as a result of the appearance of new substances on the market, the changes in inhabitant lifestyle and the catchment characteristic; therefore, it must be constantly monitored. At the same time, due to the time-consuming and high costs of measurement campaigns, solutions that could limit their scope and facilitate the interpretation of the results are sought. This paper presents the results of the measurement campaign conducted in 2018–2021. The aim of the monitoring was, inter alia, assessment of wastewater composition in terms of threats to wastewater treatment plant and urban rivers, which are receivers of discharge from combined sewer overflows. The obtained results were analyzed using the multivariate statistical methods: Principal Component Analysis and Cluster Analysis. However, the applied methods did not allow for the full identification of the relationship between the wastewater quality parameters as well as the differences and similarities in the wastewater composition from individual parts of the city, which could simplify and reduce the measurement campaigns in the future. Therefore, in the case of large urban catchments, it is necessary to introduce other solutions to control the wastewater composition. [ABSTRACT FROM AUTHOR]

The present study tracked the city-wide dynamics of severe acute respiratory syndrome-corona virus 2 ribonucleic acids (SARS-CoV-2 RNA) in the wastewater from nine different wastewater treatment plants (WWTPs) in Jaipur during the second wave of COVID-19 out-break in India. A total of 164 samples were collected weekly between February 19th and June 8th, 2021. SARS-CoV-2 was detected in 47.2% (52/110) influent samples and 37% (20/54) effluent samples. The increasing percentage of positive influent samples correlated with the city's increasing active clinical cases during the second wave of COVID-19 in Jaipur. Furthermore, wastewater-based epidemiology (WBE) evidence clearly showed early detection of about 20 days (9/9 samples reported positive on April 20th, 2021) before the maximum cases and maximum deaths reported in the city on May 8th, 2021. The present study further observed the presence of SARS-CoV-2 RNA in treated effluents at the time window of maximum active cases in the city even after tertiary disinfection treatments of ultraviolet (UV) and chlorine (Cl2) disinfection. The average genome concentration in the effluents and removal efficacy of six commonly used treatments, activated sludge process + chlorine disinfection (ASP + Cl2), moving bed biofilm reactor (MBBR) with ultraviolet radiations disinfection (MBBR + UV), MBBR + chlorine (Cl2), sequencing batch reactor (SBR), and SBR + Cl2, were compared with removal efficacy of SBR + Cl2 (81.2%) > MBBR + UV (68.8%) > SBR (57.1%) > ASP (50%) > MBBR + Cl2 (36.4%). The study observed the trends and prevalence of four genes (E, RdRp, N, and ORF1ab gene) based on two different kits and found that prevalence of N > ORF1ab > RdRp > E gene suggested that the effective genome concentration should be calculated based on the presence/absence of multiple genes. Hence, it is imperative to say that using a combination of different detection genes (E, N, RdRp, & ORF1ab genes) increases the sensitivity in WBE. [ABSTRACT FROM AUTHOR]

Sewer systems are reservoirs of pathogens and bacteria carrying antibiotic resistance genes (ARGs). However, most recent high-throughput studies rely on DNA-based techniques that cannot provide information on the physiological state of the cells nor expression of ARGs. In this study, wastewater and sewer sediment samples were collected from combined and separate sanitary sewer systems. The metabolically active prokaryote community was evaluated using 16S rRNA amplicon sequencing and actively transcribed ARG abundance was measured using mRNA RT-qPCR. Three (sul1, blaTEM, tet(G)) of the eight tested ARGs were quantifiable in select samples. Sewer sediment samples had greater abundance of actively transcribed ARGs compared to wastewater. Microbiome analysis showed the presence of metabolically active family taxa that contain clinically relevant pathogens (Pseudomonadaceae, Enterobacteraceae, Streptococcaceae, Arcobacteraceae, and Clostridiaceae) and corrosion-causing prokaryotes (Desulfobulbaceae and Desulfovibrionaceae) in both matrices. Spirochaetaceae and methanogens were more common in the sediment matrix while Mycobacteraceae were more common in wastewater. The microbiome obtained from 16S rRNA sequencing had a significantly different structure from the 16S rRNA gene microbiome. Overall, this study demonstrates active transcription of ARGs in sewer systems and provides insight into the abundance and physiological state of taxa of interest in the different sewer matrices and sewer types relevant for wastewater-based epidemiology, corrosion, and understanding the hazard posed by different matrices during sewer overflows. [ABSTRACT FROM AUTHOR]

Overflow mechanisms can be found in a variety of queueing models. This paper studies a simple and generic overflow system that allows the service times to be both job type and station dependent. This system does not exhibit a product form. To justify simple product form computations, two product form modifications are given, as by a so-called call packing principle and by a stop protocol. The provided proofs are self-contained and straightforward for the exponential case and of merit by itself. Next, it is numerically studied whether and when, or under which conditions, the modifications lead to a reasonable approximation of the blocking probability, if not an ordering. The numerical results indicate that call packing provides a rather accurate approximation when the overflow station is not heavily utilized. Moreover, when overflowed jobs have an equal or faster service rate, the approximation is consistently found to be pessimistic, which can be useful for practical purposes. The stop protocol, in contrast, appears to be less accurate for most natural situations. Nevertheless, for an extreme situation the order might change. In addition, for the stop protocol the product form is proven to be insensitive (i.e. to also apply for arbitrary non-exponential service times). For call packing, this numerically appears not to be the case, as of interest by itself. However, from a practical viewpoint the sensitivity seems light. The results are intriguing for both theoretical and practical further research. [ABSTRACT FROM AUTHOR]

At a global level, it has been scientifically reported that the processes of water purification, management and disposal of wastewater, and solid waste generate environmental impacts, especially they contribute to global warming potential (GWP), which, in turn, is caused by the greenhouse gases emissions (GHGs). In this context, the main objective of the present research has been to assess the GWP of the water treatment, sewer and sanitation services of the city of Pamplona (Colombia) with a population of 50.000 inhabitants through Life Cycle Assessment but focusing only on the global warming potential impact. The results show that the operation of the three services emitted 1.07E+01 kg CO2-eq per inhabitant and per year, which emissions of GWP produced in water treatment is the most influential utility, accounting for 66% of the entire GWP, while the CO2 emitted from the sewer accounts for 20%, and the sanitation count for 14% of the total. Finally, strategies leading to the mitigation of the adverse GHGs currently produced by these public utilities are proposed. [ABSTRACT FROM AUTHOR]

Accounting for SARS-CoV-2 adsorption on solids suspended in wastewater is a necessary step towards the reliable estimation of virus shedding rate in a sewerage system, based on measurements performed at a terminal collection station, i.e., at the entrance of a wastewater treatment plant. This concept is extended herein to include several measurement stations across a city to enable the estimation of spatial distribution of virus shedding rate. This study presents a pioneer general model describing the most relevant physicochemical phenomena with a special effort to reduce the complicated algebra. This is performed both in the topology regime, introducing a discrete-continuous approach, and in the domain of independent variables, introducing a monodisperse moment method to reduce the dimensionality of the resulting population balance equations. The resulting simplified model consists of a large system of ordinary differential equations. A sensitivity analysis is performed with respect to some key parameters for a single pipe topology. Specific numerical techniques are employed for the integration of the model. Finally, a parametric case study for an indicative—yet realistic—sewerage piping system is performed to show how the model is applied to SARS-CoV-2 adsorption on wastewater solids in the presence of other competing species. This is the first model of this kind appearing in scientific literature and a first step towards setting up an inverse problem to assess the spatial distribution of virus shedding rate based on its concentration in wastewater. [ABSTRACT FROM AUTHOR]

This paper researches the existence of economies of scale and scope in the Chilean water and sewerage industry using a translog cost function approach over the period 2010–2017. It also provides estimates of productivity growth and its determinants, technical change and scale effect. The results suggest that on average, the water industry operates under increasing economies of scale, which implies that further increases in water companies' scale of operations may be cost beneficial. Economies of scope between water and sewerage services were found for the average company, which suggests that the joint provision of these services may lead to cost savings. An average annual productivity increase of 2.5% was reported with scale effect being the major driver. Full private companies performed better than concessionary and public water companies. The results of our study can be of greater interest to the policy-makers who want to make decisions on introducing policy reforms such as mergers, unbundling of the water and sewerage supply chain, or developing incentives to improve companies' productivity. [ABSTRACT FROM AUTHOR]

In cities, the existence of impervious structures, such as road pavements, parking lots, footpaths, sidewalks, and roofs, can limit the magnitude of rainfall infiltration greatly. Stormwater run-off in storm sewer often dominates, which can cause problems of urban flooding easily during heave rainfalls. In rain and sewage diversion, perforated storm sewer is proposed to enable the occurrence of stormwater infiltration into the ground, which can change the prolonged drought-like condition. Model-scale laboratory tests are conducted to assess the infiltration process of water through drainage holes around the sewer circumference. The experimental data are also used to calibrate a numerical model, after which numerical parametric analysis is carried out. It is found that the feature of drainage holes only influences the wetting front in the initial stage of infiltration. In the end, the egg-shaped contour of wetting front with greater influencing zone below the sewer is obtained. The cumulative infiltration with time can be described by an infiltration model, which is positively correlated with the diameter and the number of drainage holes. The optimal opening ratio is recommended as 0.25%, which can provide the most effective drainage capacity. [ABSTRACT FROM AUTHOR]

A growing literature indicates that untreated wastewater from leaky sewers stands among major sources of pollution to water resources of urban systems. Despite that, the quantification and allocation of sewer exfiltration are often restricted to major pipe areas where inspection data are available. In large-scale urban models, the emission from sewer exfiltration is either neglected (particularly from private sewers) or represented by simplified fixed values, and as such its contribution to the overall urban emission remains questionable. This study proposes an extended model framework which incorporates sewer exfiltration pathway in the catchment model for a better justified pollution control and management of urban systems at a nationwide scale. Nutrient emission from urban areas is quantified by means of the Modelling of Nutrient Emissions in River Systems (MONERIS) model. Exfiltration is estimated for public and private sewers of different age groups in Germany using the verified methods at local to city scales, upscaling techniques, and expert knowledge. Results of this study suggest that the average exfiltration rate is likely to be less than 0.01 L/s per km, corresponding to approximately 1 mm/m/year of wastewater discharge to groundwater. Considering the source and age factors, the highest rate of exfiltration is defined in regions with significant proportions of public sewers older than 40 years. In regions where public sewers are mostly built after 1981, the leakage from private sewers can be up two times higher than such from public sewers. Overall, sewer exfiltration accounts for 9.8% and 17.2% of nitrate and phosphate loads from urban systems emitted to the environment, which increases to 11.2% and 19.5% in the case of no remediation scenario of projected defective sewer increases due to ageing effects. Our results provide a first harmonized quantification of potential leakage losses in urban wastewater systems at the nationwide scale and reveal the importance of rehabilitation planning of ageing sewer pipes in public and private sewer systems. The proposed model framework, which incorporates important factors for urban sewer managers, will allow further targeting the important data need for validating the approach at the regional and local scales in order to support better strategies for the long-term nutrient pollution control of large urban wastewater systems. [ABSTRACT FROM AUTHOR]

Urbanization and climate change have resulted in an increase in catchment runoff, often exceeding the designed capacity of sewer systems. The decision to modernize a sewer system should be based on appropriate criteria. In engineering practice, the above is commonly achieved using a hydrodynamic model of the catchment and the simulation of various rainfall events. The article presents a methodology to analyze the effect of rainfall characteristics parametrized with intensity-duration-frequency (IDF) curves in regard to performance measures of sewerage networks (flood volume per unit impervious surface and share of overfilled manholes in the sewerage network) accounting for the model uncertainty determined via the generalized likelihood uncertainty estimation (GLUE) method. An urban catchment was modeled with the Storm Water Management Model (SWMM). Analyses showed that the model uncertainty exerts a large impact on certain measures of sewage network operation. Therefore, these measures should be analyzed in similar studies. This is very important at the stage of decision making in regard to the modernization and sustainable development of catchments. It was found that among the model parameters, the Manning roughness coefficient of sewer channels yields a key impact on the specific flood volume, while the area of impervious surfaces yields the greatest impact on the share of overflowed manholes. [ABSTRACT FROM AUTHOR]

The central sewer of Athens had been discharging untreated sewage from 1950 until 1995 in the marine area between the island of Psyttalia and Keratsini. As a result, a surficial layer of organic mud was formed covering the seafloor. To assess the spatial and temporal distribution of metal contaminants in the area, six sediment cores were collected and analyzed for grain composition, organic carbon content (Corg), and metal concentrations. ICP-MS and AAS were used to determine the following metal concentrations: Cu, Zn, Mo, Ag, Cd, Cr, Pb, Ni, Fe, As, Mn, and Co. Four different lithofacies were identified based on grain size and macroscopic observations. The contamination of the sediments was assessed according to Enrichment factor (EF), Geo-accumulation Index (Igeo), and Pollution Loading Index (PLI), the latter was used in order to assess the overall toxicity status of the sediments. Factor analysis was also performed in the heavy metal, Corg, and Ca datasets. R-mode factor analysis indicates at least three different pollution sources in the area, while Q-mode analysis indicates three different groups of sediment samples according to their pollution degree. The present work stands among others to contribute to the better knowledge of the environmental impact of urban wastes on the shallow marine sediments adjoining large cities areas. [ABSTRACT FROM AUTHOR]

This research is about development of the in-pipe robot for heavy duties, such as repairing and maintenance tasks, by focusing on the sewers between households or businesses to the main sewers. The robot is expected to work instead of workers to help them work easier and safer, such as in small pipe that the workers cannot access or dirty and dangerous environment that can affect to the health and life of the workers. The most conventional robots in the past were mainly designed for survey and inspection. While some robots focus on maintenance task, but their robots are not available for small pipe and their manipulator have a few DOF. Then, we propose a compact in-pipe robot with multi-DOF cutting tool (CIPbot-1) for the target pipes between 150 and 300 mm in diameter to enhance the ability of these kind of robot. The difficulties of development this robot is the space limitation caused by the smallest target pipe which affects to the mechanism design, and the rigidity of robot's structure. The expandable mechanisms must be able to adjust the diameter of the robot about 2 times to fit with the smallest and the biggest target pipes. The proposed robot mainly consists of a locomotion section (adjustable folding mechanism and six-crawlers, each of them is driven by only one motor) and a manipulator Sect. (3-DOF manipulator with a cutting tool and a camera system for inspection). The prototype of CIPbot-1 was made and confirmed the mobility, the ability, and the usefulness by the experimentations. [ABSTRACT FROM AUTHOR]

This study focused on the performance and limitations of the local inertial approximation form model (LIM) of the shallow water equations (SWEs) when applied in urban flood modeling. A numerical scheme of the LIM equations was created using finite volume method with a first-order spatiotemporal Roe Riemann solver. A simplified urban stormwater model (SUSM) considering surface and underground dual drainage system was constructed based on LIM and the US Environmental Protection Agency Storm Water Management Model. Moreover, a complete urban stormwater model (USM) based on the SWEs with the same solution algorithm was used as the evaluation benchmark. Numerical results of the SUSM and USM in a highly urbanized area under four rainfall return periods were analyzed and compared. The results reveal that the performance of the SUSM is highly consistent with that of the USM but with an improvement in computational efficiency of approximately 140%. In terms of the accuracy of the model, the SUSM slightly underestimates the water depth and velocity and is less accurate when dealing with supercritical flow in urban stormwater flood modeling. Overall, the SUSM can produce comparable results to USM with higher computational efficiency, which provides a simplified and alternative method for urban flood modeling. [ABSTRACT FROM AUTHOR]

Sewer networks are mainly composed of pipelines which are in charge of transporting sewage and rainwater to wastewater treatment plants. A failure in a sewer pipe has many negative consequences, such as accidents, flooding, pollution or extra costs. Machine learning arises as a very powerful tool to predict these incidents when the amount of available data is large enough. In this study, a real-coded genetic algorithm is implemented to estimate the optimal weights of a logistic regression model whose objective is to forecast pipe failures in wastewater networks. The goal is to create an autonomous and independent predictive system able to support the decisions about pipe replacement plans of companies. From the data processing to the validation of the model, all stages for the implementation of the machine-learning system are explored and carefully explained. Moreover, the methodology is applied to a real sewer network of a Spanish city to check its performance. Results demonstrate that by annually replacing 4% of pipe segments, those whose estimated failure probability is higher than 0.75, almost 30% of unexpected pipe failures are prevented. Furthermore, the analysis of the estimated weights of the logistic regression model reveals some weaknesses of the network as well as the influence of the features in the pipe failures. For instance, the predisposition of vitrified clay pipes to fail and of that pipes with smaller diameters. [ABSTRACT FROM AUTHOR]

The paper presents possibilities of application of selected regression methods (classification trees, support vector machines, K-nearest neighbours, artificial networks) for classification of sewers' damages. Operational data from the time span 2006–2011 obtained from water utility were used for deterioration analysis. On the basis of the following independent variables, the modelling was carried out: diameter, depth, year of construction, material and season of damage's occurring. The following kinds of damages were classified: corrosion, crack, longitudinal crack, displacement, unsealing, failure, collapse. The main aim of the paper was to check if prediction methodology could be useful for classification of different kinds of sewers' damages. The obtained results pointed out that proposed classification methods are not appropriable in quality analysis of registered damages of sewers. Moreover, it is recommended for water and sewerage companies to register types of failures using unified notation which make easier preliminary classification before applying modelling approach. The calculations were performed in Statistica 13.1 software. [ABSTRACT FROM AUTHOR]

Once a wastewater treatment plant (WWTP) exceeds its capacity, it is necessary to discharge a proportion of the flow to watercourses through combined sewer overflow (CSO) structures. In coastal urban areas, CSO spills may occur in seawaters. The present study analyses the effects of these spills into urban coastal bathing areas, through a qualitative survey-based analysis in Badalona and Barcelona, focusing on stakeholders' reputation and image involved in the sewer system and beaches management (i.e. intangible damages) and the consequences for the economy (i.e. tangible damages). The direct relation between CSO spills and impacts on restaurants' revenues is not observed since business owners in Badalona and Barcelona do not perceive any economic impact due to these events. Their main concern is the municipality's image, which might affect the citizens' view of the management of the responsible agents and indirectly, the tourist sector, especially in Barcelona. Residents perception in this matter is remarkably different in both cities. In Badalona, residents know the problem and even the body responsible for setting the red flag and the beaches closure (i.e. the municipality). In Barcelona, though, residents are quite confused about this. The complexity in terms of competencies in sewer systems management requires a better communication campaign for the citizens to avoid misunderstandings and unnecessary loss of trust in the City Council. Decision-makers and stakeholders should be interested in understanding the perception of affected users upon these events to take appropriate measures to enhance awareness programs or measures to reduce overflows. [ABSTRACT FROM AUTHOR]

Sewer systems are an integral part of our modern civilization and are an imperative underground infrastructure asset that our society relies on. In Western Europe alone, 92% of the resident pollution is connected to sewer systems. This extensive coverage of sewerage systems presents an ideal habitation for microorganisms to strive. Sewers can be considered continuous flow bioreactors. They are always colonized by bacteria, either in a planktonic state traveling along the pipe with the water flow or dragged in sediment, or organized as biofilms. Many studies have been devoted to the detrimental effects of microorganisms on sewer systems made of concrete. However, their metabolic activity can also be beneficial, lead to more effective wastewater treatment, or be beneficial for concrete pipes. This aspect has not been thoroughly studied to date and requires further investigation. Therefore, in this Review, we highlighted the positive and negative activity of biofilms and their participation in five proposed mass exchange points in gravity sewers. Furthermore, we systematized and reviewed state of the art regarding methods that could be potentially used to remove or engineer these biological structures to increase the sustainability of sewers and achieve a better pre-treatment of wastewater. We have also indicated research gaps that could be followed in future studies. [ABSTRACT FROM AUTHOR]

The damage on supply and drainage water networks is a serious cause of economic disruption for urban systems affected by earthquakes. Among various concerns, the ruptures of sewer pipes and manholes generated by liquefaction determine a particularly severe sanitary hazard and require extensive, costly and time-consuming repairs. Quantitative risk assessment carried out with the characterisation and geographical mapping of seismic hazard, subsoil susceptibility, physical and functional vulnerability of the exposed elements, enables to estimate losses, identify weaknesses, inspire strategies to mitigate the impact of earthquakes and improve resilience. The present study deals with the physical vulnerability of sewer pipelines. Empirical fragility functions are derived from the evidences of liquefaction induced in Urayasu (Japan) by the 2011 Tohoku-Oki earthquake (Mw9.0). The spatial distribution of seismic signals, subsoil characteristics, pipes and surveyed damages are reconstructed in a GIS platform. An articulated methodology is developed to correlate variables and compensate their limited spatial correspondence, exploiting the complete coverage of the area with terrestrial settlements measured by LiDAR and their strong correlation with damage. Finally, ruptures of pipes are probabilistically quantified adopting a common liquefaction severity indicator as engineering demand parameter and measuring the efficiency of relations with statistical tests. [ABSTRACT FROM AUTHOR]