Urban Sewer Systems Research Articles

Environmental drivers of sediment accumulation in urban sewer systems: a case study of Kyoto City, Japan

Sediment accumulation can reduce the drainage capacity of sewer systems, and thus increase the risk of urban flooding and jeopardize the safety of urban environments. The interaction between multiple environmental factors drives sedimentation in sewer systems, but this interaction is poorly understood. To fill this gap, this study examined the interaction between five categories of environmental factors (population, traffic, climate, air quality, and wastewater quality: 25 factors overall) and the effects of these factors on sediment accumulation in different sewer system structures (open channels (OCs), circular channels (CCs), junctions) in Kyoto, Japan, from 2014 to 2023. The results showed that population and traffic contributed to sediment accumulation through pollutant emission, whereas climate factors promoted sediment accumulation by enhancing wash-off and the deposition of air pollutants. Most sediment was deposited in OCs and junctions under the combined effects of climate and air quality. Air quality has a greater influence on sedimentation in the OCs than climate, and the opposite is found for Junction, whereas sedimentation in CCs was mainly influenced by the combined effects of climate, air quality, and wastewater quality. Photochemical oxidants, humidity, temperature, and vapor pressure had the greatest impact on sediment deposition in OCs and junctions, while wastewater alkalinity and NH4-N and PO4-P concentration had a non-negligible effect on CCs sedimentation. These results emphasize the key role of climate-driven wash-off and dry/wet deposition, and the localized role of wastewater quality (in CCs), in sewer sedimentation. These insights can inform the predictive modeling of sewer sedimentation during climate change.

Effect of rainfall-derived inflow and infiltration on dissolved organic matter in urban sanitary sewers using chemometric and machine learning approaches

This study investigated changes in dissolved organic matter (DOM) properties within urban sanitary sewers influenced by groundwater infiltration and excessive rainfall-derived inflow and infiltration (RDII). It employed optical indices and fluorescence excitation-emission matrix-parallel factor analysis (PARAFAC) coupled with self-organizing map (SOM) to compare DOM characteristics during wet weather flows (WWFs) and dry-weather flows (DWFs). Sampling sites impacted by RDII were identified based on flowrate. Optical indices and PARAFAC components (C1–C4) were used to differentiate DOM properties between DWFs and WWFs. In WWFs, E<sub>2</sub>/E<sub>3</sub> and S<sub>350-400</sub> increased, while spectral ratio (S<sub>R</sub>) decreased, indicating a shift towards smaller organic matters. Reduced fluorescence and humidification indices suggested the input of fresher/terrestrial organic matters. C3 and C4 exhibited significant distinctions, showing increased C3 and decreased C4 levels. The PARAFAC-SOM modeling further illustrated that water samples in the urban sewer system could be categorized based on the dominance of DOM properties. Principal component analysis revealed separation between DWF and WWF samples in principal component 1 (PC1), associated with molecular size. PC2 was linked to microbial activity in WWFs. Notably, DWF samples from the NY-11 site shifted to the positive side of the PC1 axis, while their corresponding WWF samples moved to the negative side.

The heterogeneous impact of population mobility on the influent characteristics of wastewater treatment facilities

Improving the resilience of wastewater treatment facilities (WWTFs) has never been more important with rising risks of disasters under climate change. Beyond physical damages, non-physical shocks induced by disasters warrant attention. Human mobility is a vital mediator in transferring the stresses from extreme events into tangible challenges for urban sewage systems by reshaping influent characteristics. However, the impact path remains inadequately explored. Leveraging the stay-at-home orders during the COVID-19 pandemic as a natural experiment, this study aims to quantify and interpret the heterogeneous impacts of mobility reduction on the influent characteristics of WWTFs with different socio-economic, infrastructural, and climatic conditions. To achieve this goal, we developed a research framework integrating causal inference and interpretable machine learning techniques. Based on the empirical data from China, we find that 79.1% of the studied WWTFs, typically located in cities with well-developed drainage infrastructures and low per capita water usage, exhibited resilience against drastic mobility reduction. In contrast, 20.9% of the studied WWTFs displayed significant variations in influent characteristics. Large-capacity WWTFs in subtropical regions encountered challenges with low-load operations, and small-capacity facilities in suburban areas grappled with nutrient imbalances. This study provides valuable insights to equip WWTFs in anticipating and adapting potential variations in influent characteristics triggered by mobility reduction.

Microbiological Surveillance of Salmonella Strains in the Effluents of the Teaching Hospital (CHU) of Yopougon and Cocody, Côte d'Ivoire

Diarrhoeal diseases are a major public health problem worldwide, with salmonellosis being a leading cause of foodborne illness in humans. Environmental pollution from healthcare activities, particularly from the discharge of hospital effluent into urban sewer systems, poses a significant threat. These effluents can carry microorganisms, antibiotic residues and detergents that contribute to the development and spread of bacterial multiresistance. In Abidjan, the capital of Côte d'Ivoire, hospital wastewater is not treated before being discharged into the sewer system. This untreated wastewater eventually flows into the Ebrié lagoon, a critical water source for many local communities. The dependence of the lagoon's population on these waters raises significant public health concerns, particularly with regard to potential contamination with pathogenic bacteria such as Salmonella. The aim of this study was to assess the presence of Salmonella in hospital wastewater to understand the risk of contamination and to inform potential mitigation strategies. A total of 60 wastewater samples were collected: 30 from the teaching hospital (CHU) of Yopougon and 30 from Cocody. Upon analysis, no Salmonella sp strains were detected in any of the samples. However, 28 bacterial strains exhibiting characteristics similar to Salmonella were isolated, suggesting the presence of potentially virulent pathogens. In Yopougon's samples, 14 strains of Proteus mirabilis and 2 strains of Klebsiella sp were identified. In Cocody 's samples, 12 strains of Citrobacter freundii sp were isolated. These findings highlight the importance of monitoring and treating hospital wastewater to prevent the spread of potentially harmful bacteria into the environment.

Green infrastructure layout based on a dynamic operation feature of drainage systems.

Increasingly frequent urban floods strain the traditional grey infrastructure, overwhelming the capacity of drainage networks and causing challenges in managing stormwater. The heavy precipitation leads to flooding and damage to drainage systems. Consequently, efficient mitigation strategies for flooding have been researched deeply. Green infrastructure (GI) has proved to be effective in responding the increasing risk of flood and alleviate pressure on drainage systems. However, as the primary infrastructure of stormwater management, there is still a lack of attention to the dynamic operation feature of urban sewer systems during precipitation events. To fill this gap, we proposed a novel approach that integrates hydraulic characteristics and the topological structure of a sewer network system. This approach aims to identify influential nodes, which contribute to the connectivity of the sewer network amidst dynamic changes in inflow during precipitation events. Furthermore, we adopted rain barrels to serve as exemplars of GI, and 14 GI layout schemes are produced based on the different ranks of influential nodes. Implementing GI measures on both poorly performing and well-performing nodes can yield distinct benefits in mitigating node flooding. This approach provides a new perspective for stormwater management, establishing effective synergy between GI and the drainage system.

Features of Management with Biological Waste of Patients after Radioiodotherapy in Different Countries

The analysis of existing in different countries of the world approaches to the management of liquid radioactive waste (LRW) of patients generated during radionuclide therapy with 131I is carried out. The regulated values are given, on the basis of which criteria for the discharge of LRW containing 131I into a centralized urban sewage system are established for medical organizations in a number of countries. The most common strategies for the management of patients’ LRW after radiotherapy are considered. Compliance with the discharge criteria may be achieved by delaying radioactive effluents for decay in specially designed delay tanks or by its dilution with inactive effluents of a medical organization at the discharge point. The chosen strategy should be determined by the parameters characterizing the discharges of a particular organization, so as not to affect the capacity of the department and, as a result, the availability of the radiotherapy procedure to patients in the country. Defining a case-by-case treatment strategy or using the two strategies considered in combination with each other may be a more effective practice for treating patients with LRW. The latter may be relevant for medical organizations in Russia, where the discharge criteria is conservative, and at the legal level it is prohibited to use another strategy for handling LRW, except for storage for decay.

Optimizing urban green infrastructure using a highly detailed surface modeling approach

Urban trees and forests show a better ecosystem with many benefits, including pure air quality. The development of urban green infrastructure (UGI) creates a better management system that greatly impacts social values in an urban system. The UGI and construction activities are receiving much attention for their effectiveness in addressing various urban ecological, social and economic issues. Using green infrastructure in stormwater management can reduce the influence on urban sewerage systems and, eventually, on building water resources. The main goal of the research is to optimize the green infrastructure to provide a less-pollution, well-organized, and pleasurable environment for the inhabitants. Various models are used to study the present rainfall-runoff scenario, but the stormwater management model (SWMM) is the most preferable and suggested model. Once the parameters are accessed, optimizing the green infrastructure (GI) will be easy. A complete SWMM model is evaluated over the complete surface, and a hydrological measurement is presented. The evaluation study presents various component percentages: asphalt (37%), green (27%), ceiling (21%), grit (12%), and cemented area (2%), which provides rainproof coverage of approximately 60%. A design is developed about the diverse events of GI in urban exploiting the SWMM and demonstrates its stimulus on the rainfall-runoff behaviour. In recent years, very little attention has been given to green spaces in urban areas, which not only increases pollution but also decreases the urbanization. Therefore, urban green spaces are more important to improve air quality and resident living standards. Over the given scenario and the rainfall event, a decline of the quantitative discharge parameters is evident, such as discharge volume (i.e., from 3.6 to 61.8) and the peak discharge rate (i.e., from 5.4 to 62.7%). The simulation results show that green areas give high satisfaction with low construction costs, which shows the superlative performance ratio of the examined measures. From the investigation, it is also recommended to have green areas and public spaces in impervious urban areas, which greatly reduced the runoff in the project area.

Domestic sewage dispersion scenarios as a subsidy to the design of urban sewage systems in the Lower Amazon River, Amapá, Brazil

The final in natura discharge of urban domestic sewage in rivers in the Amazon is a widespread practice. In addition, there is an evident lack of knowledge about the self-depurative characteristics of the receiving water bodies in these rivers. This problem is a challenge for designing sanitary sewage system (SSS) projects in the region. We aimed to numerically simulate hydrodynamic scenarios to study pollutant dispersion processes in an urban stretch impacted by domestic sewage in the Lower Amazon River (Amapá, Brazil) using a hydrodynamic model calibrated and coupled to a dispersive model (Lagrangian) (SisBaHiA). The following methodological steps were performed: (a) bathymetric and liquid discharge experimental campaigns using acoustic techniques (acoustic doppler current profiler—ADCP); (b) identification of point and diffuse sources of pollution in the Santana Channel (CSA) and North Channel of the Amazon River (NCM) in Macapá; (c) calibration of the hydrodynamic model and simulation of the dispersive process of domestic sewage plumes; (d) simulation of dispersive process scenarios in two seasonal hydrological periods and different tidal phases. The results of the simulations indicated significant spatiotemporal variations in the plumes, suggesting critical restriction of water quality in the dry period. The hotspot water collection supply station for ETA-CAESA was found to be the most threatened site by diffuse and point source loads. The simulated impacts showed that concentration variation worsens seasonally, restricting the multiple uses of water in both seasonal periods, regardless of tide phase. The pollutant plumes near the coastal-urban zone were apparently more inhibited by the influence of currents, and, due to the greater dilution capacity in the center of the channel, by the effect reversing with the approximation to the riverbank. The research hypotheses were supported: (a) the process of self-depuration of pollutants in the NCM has considerable limitations in shallow areas, and (b) SSS design projects in the region of the Amazon estuarine complex require hydrodynamic and strict water quality assessment, especially when their hydrological-seasonal and bathymetric characteristics are significantly unfavorable to dispersive processes. Thus, a hydrodynamic analysis should be the primary criterion in designing any SSS projects in this stretch of the estuarine Amazon region.

Enhancement of sewer sediment control and disruption of adhesive gelatinous sediment structure using low-dose calcium peroxide

Large quantities of sediments in urban sewer systems pose significant risk of pipe clogging and corrosion. Owing to their gel-like structure, sewer sediments have strong resistance to hydraulic shear stress. This study proposed a novel approach to weaken the erosion resistance of sewer sediments by destroying viscous gel-like biopolymers in sediments with low doses of calcium peroxide (CaO2). After treatment with 10–50 mg g−1 TS of CaO2, the critical erosion shear stress was significantly reduced by 25.7%–59.9%. The sediment aggregates gradually disintegrated into small diameter particles with increasing CaO2 dosage. Further analysis showed that the strong oxidizing and alkaline environment induced by CaO2 treatment led to cell lysis and changes in the composition and property of extracellular polymeric substances (EPS). After CaO2 treatment, aromatic proteins and humic acid-like substances associated with adhesion translocated from the inner EPS layers to outer layers while being disintegrated into small organic molecules. Concomitantly, CaO2 treatment disrupted the main functional groups (–OH, COO−, C–N, CO, and CN) in inner EPS layers, thus weakening EPS adhesion. Analysis of protein secondary structure and zeta potential reflected the reduced aggregation capacity of sediment microorganisms and loosening of sediment structure after CaO2 treatment. Thus, CaO2 treatment facilitated fragmentation and disaggregation of the gelatinous structure of sewer sediments. Such green strategy decreased the cost of sewer sediment disposal by 42.10–68.95% when compared to water flushing, and it would improve the self-cleaning capacity of sewer system and efficiency of dredging equipment.

Transport of non-flushable wipes in sewers and its application in sewer management

Flushing wipes into sewers has caused severe blockage issues in urban sewer systems, especially during the COVID-19 pandemic; however, the transport mechanism of wipes in sewers has not been reported. To address this knowledge gap, the transport of non-flushable wipes with different densities was systematically studied in a circular pipe. The critical shear stress and flow velocity for the incipient motion of wipes were found to increase with increasing wipe density and with decreasing relative wipe size, starting from 0.02 Pa and 0.05 m/s, respectively. Non-dimensional equations were developed for characterizing the incipient motion using two parameters: the critical Shield number and particle Froude number. The mean wipe velocity, mean ambient flow velocity, and wipe density could be well described by a power relationship. The ratio of wipe velocity to local flow velocity increased with the increase of wipe vertical position in the pipe. Different movement modes of wipes were observed and classified by using the ambient cross-sectional average velocity Ua: the sliding mode started first, followed by rolling/saltation at Ua = 0.18 m/s and suspension at Ua = 0.41 m/s. The threshold values for each mode were found to increase with increasing wipe density. Finally, the research results were applied in sewer management.

The telltale fluorescence fingerprints of sewer flows for interpreting the low influent concentration in wastewater treatment plant

Low degradability of wastewater treatment plant (WWTP) influents negatively affects its ability to effectively remove pollutants through wastewater treatment processes. Proactive assessment of urban sewer system performance is highly valued in the selection of targeted countermeasures for this occurrence. In this study, a fluorescence spectrum interpretation approach was developed to identify the causes of low biodegradability of WWTP influent by using parallel factor analysis (PARAFAC) and fluorescence regional integration (FRI) of excitation-emission matrix spectroscopy. Statistical analysis was also used to further interpret the PARAFAC- and FRI-derived data. The urban sewer catchment served by a WWTP in Wuhan City, China, was used as the test site to demonstrate the effectiveness of this approach. The results showed that electronics manufacturing industrial wastewater and groundwater input into the urban sewer would significantly decrease the biodegradability of the WWTP influents, and these sources were characterized by much lower fluorescence peak intensities, especially for protein-like substances, including tryptophan-like T and tyrosine-like B1 and B2. The potential conversion of high freshness T into low freshness B2 within the sewer may also contribute to this undesirable scenario. The ratio of peak T to peak B2 and the ratio of the FRI fraction of region I to that of region II can be used together to determine the predominance of industrial wastewater and groundwater. T/B2 < 1.3 indicates the entry of industrial wastewater or groundwater into urban sewers, and I/II > 0.5 further confirms the input of industrial wastewater. Accordingly, the low biodegradability of the WWTP influents in our study site is mostly due to the inflow of industrial wastewater rather than groundwater infiltration into the urban sewers. Therefore, actions should be focused on the surveillance of industrial wastewater rather than widespread sewer inspection and repairs. In this way, this methodology is cost-effective in aiding targeted countermeasures to improve the urban sewer system performance.

Urban flood numerical modeling and hydraulic performance of a drainage network: A case study in Algiers, Algeria.

Urban sewer system management is challenging due to its higher vulnerability to flooding caused by rapid urbanization and climate change. For local decision-makers, storm water management is essential for urban planning and development. Therefore, the main objective of this study is to develop a numerical model for the sewerage network of the central catchment area of Algiers since it has experienced frequent overflows during the winter season. For this purpose, to model the sewerage networks, the model was built by coupling ArcGIS with MIKE URBAN. Its calibration and validation were performed using real-time measurements with a time step of 15 min. The model was evaluated by several statistical indicators, such as the coefficient of determination (R2), Nash-Sutcliffe efficiency (NSE), root mean square error (RMSE), and percent bias (PBIAS). The model results showed acceptable model performance, with an NSE superior to 0.50, R2 of approximately 0.63, RMSE of 7%, and PBIAS of 10% during the validation of the model. The performance parameters prove the reliability of the developed model. The employed model can be applied in other regions and could be helpful for policymakers and managers to improve flood mitigation measures based on the model prediction of the sewerage network.

Formation characteristics of bacteria and fungi in sewers: In terms of signal molecule generation

Bio-metabolism of diverse communities is the main reason of water quality variation in sewers, and the signal molecule generation of communities is dementated to be the key regulation procedure for community metabolism. To reveal the mechanism of pollutant biotransformation in complex sewer environment, this study explored the formation of bacteria and fungi and the signal molecule transduction characteristics in a pilot sewer. In this study, several kinds of signal molecules that produced by bacteria and fungi (C4-HSL, C6-HSL, C8-HSL, farnesol and tyrosol) were detected along the formation process of sewer biofilms. The results showed that, in the early stage, bacterial AHLs signaling molecules are beneficial to the synthesis of EPS, providing a good material basis for the growth of bacterial flora. In addition, tyrosol stimulates the formation of embryonic tubes in yeast cells, further promoting the growth of hyphae. At the later stage, AHLs signaling molecules and tyrosol jointly promoted the growth of biofilms. In conclusion, it is precisely because of the coexistence of bacteria and fungi in the sewer system that the generated signal molecules can jointly promote the synthesis and growth of biofilms through different pathways, and have positive feedback on the biodegradation of various pollutants. Based on the exploration, the ecological patterns of bacterial-fungal communities in urban sewer system were proposed and it could improve the understanding on the pollutant transformation behaviors in sewers.

Assessment of Bacteriological Quality and Physiochemical Parameters of Domestic Water Sources in Jenin Governorate: A Case Study.

Water quality of drinking water is a concern in Palestine due to possible pollution sources. There is a demand for investigating the quality of municipal water supply. This study aimed to assess the quality of domestic water in Jenin Governorate located in the north of the West Bank. The methodology of this research was based on field sampling and laboratory standard testing. The tested parameters included (1) physicochemical parameters of electrical conductivity, turbidity, total hardness, salinity, pH, and total alkalinity, (2) chemical contents including the contents of nitrate, nitrite, sulfate, chloride, sodium, potassium, aluminum, and fluoride, and (3) biological contents including total coliforms and fecal coliforms. The water quality parameters were compared with the acceptable limits set by local and international standards. The findings confirm that most of the values of the investigated parameters are within the acceptable standard limits. No pollution of heavy metals is detectable. On the other hand, there are limited pollution contents in terms of the total dissolved solid (TDS), total hardness, and calcium. Furthermore, the biological parameters indicate that there are low to very high risks in a fraction of the water quality samples in terms of total coliforms and fecal coliforms. This is believed to be due to the presence of septic tanks in the neighborhoods of the sampling locations. For these cases, biological disinfection treatments are recommended before human use with an essential need for the construction of urban sewer systems. Furthermore, water treatment for harness removal may be required.

Statistical quality control based on control charts and process efficiency index by the application of fuzzy approach (case study: Ha'il, Saudi Arabia).

Fuzzy methods using linguistic expressions and fuzzy numbers can provide a more accurate examination of manufacturing systems where data is not clear. Researchers expanded fuzzy control charts (CCs) using fuzzy linguistic statements and investigated the current process efficiency index to evaluate the performance, precision, and accuracy of the production process in a fuzzy state. Compared to nonfuzzy data mode, fuzzy linguistic statements provided decision makers with more options and a more accurate assessment of the quality of products. The fuzzy index of the actual process efficiency analyzed the process by considering mean, target value, and variance of the process simultaneously. Inspection of household water meters in Ha'il, Saudi Arabia showed the actual process index values were less than 1, indicating unfavorable production conditions. Fuzzy methods enhance the accuracy and effectiveness of statistical quality control in real-world systems where precise information may not be readily available. In addition, to provide a new perspective on the comparison of urban water and sewage systems, the results obtained from fuzzy-CC were compared with various machine learning methods such as artificial neural network and M5 model tree, in order to identify and understand their respective advantages and limitations.

Multidrug-resistant Escherichia coli and Klebsiella pneumoniae isolated from hospital sewage flowing through community sewage system and discharging into the Indian Ocean

BackgroundHospital sewage is a significant reservoir of antimicrobial-resistant pathogens and genes that pose a huge public health threat. In this study, we determined the occurrence of multidrug-resistant Escherichia coli and Klebsiella pneumoniae in sewage flowing from a referral hospital through the urban sewage system to the point of discharge in the Indian Ocean.ResultsA total of 400 sewage samples were collected, yielding 517 isolates. Of these, 32.3% (167/517) were from hospital sewage, while 67.7% (350/517) were from the community. E. coli was the most common isolate (44.5% (230/517)), followed by K. pneumoniae at 27.3% (141/517), and other gram-negative bacteria constituted 28.2% (146/517) of the isolates. Multidrug resistance (MDR) was seen in 80.9% (186/230) E. coli and 71.6% (101/141) K. pneumoniae. Of the MDR isolates, 27.2% (78/287) were resistant to four different classes of antibiotics, while 6.9% (20/287) exhibited resistance to eight classes. The most frequent MDR pattern was PEN/CEP/TET/QNL/SUL, seen in 14.2% (38/287) of the isolates. The isolation frequency of MDR E. coli and K. pneumoniae at different sampling sites was high, being 47.6% in hospital chambers, 62.0% in hospital ponds, 58.1% in the treated hospital wastewater, and 55.6% in the community stream draining into the Indian Ocean. Extended spectrum beta-lactamase production was observed in 40% (92/230) of E. coli and 36.2% (51/141) of K. pneumoniae isolates. Resistance to quinolones among E. coli was 54.8% (126/230) and was 39.7% in K. pneumoniae (56/141). Carbapenem resistance in E. coli was 39.6% (91/230), while among K. pneumoniae isolates was 32.6% (46/141).ConclusionsWe found high proportions of multidrug-resistant E. coli and K. pneumoniae in the wastewater flowing from the hospital through the community sewage system to the point where it enters the Indian Ocean. Biological treatment did not significantly reduce the proportion of resistant bacteria, posing a very serious public health threat. The release of these highly resistant pathogens into the Indian Ocean is of international concern.

Plastic and its Side Effects on Humans – A Review Article

Plastics are non-biodegradable synthetic substances produced by chemical reactions. Except few test resins derived from corn and other organic substances, almost all plastics are made from carbon and petroleum. The invention of plastics alterated our society by introducing a huge spreading of products and has displaced many traditional materials. We use plastic in countless ways in our daily life such as food storage containers, electric wiring, toys, furniture, clothes, injection, syringes water, and milk bottles, packaging and carry bags, pipes, electronic items, frames, and other several thousands of items. A polymer of carbon and hydrogen alone or with nitrogen, chlorine, oxygen, or sulfur is the backbone of the majority of plastics. Plastic is a non- biodegradable material. Plastic pollutes the air, earth, and water as they contain toxic chemicals. Ethylene oxide, benzene, and xylenes are highly toxic and these are the major chemicals that go into the making of plastic and cause a serious threat to living being of all species on earth. These chemicals can cause disorders ranging from birth defects to cancer, damage the nervous system and the immune system and also affect the blood and the kidneys. Also, many toxic gases are emitted during recycling of plastic. More than 100 million tons of plastic are produced worldwide each year. Plastics do not undergo bacterial decomposition and the disposal of plastic through recycling, burning, or landfilling is a fable. Plastic wastes clog the drains and thus hit especially urban sewage systems. The plastic contaminates the water, soil, marine life and also the air we breathe, causing countless problems to living organism.

Assessment of urban landslide groundwater characteristics and origin using artificial tracers, hydro-chemical and stable isotope approaches

In the framework of landslides, the hydrogeological features play an essential role in slope stability, governing water movement and thus resulting in modification of the effective stress in the soil. In this framework, the hydrogeological conceptualization of landslide areas and the identification of groundwater origin are key points to developing risk mitigation measures. In fact, groundwater recharge cannot always be attributed to local precipitation alone. Mixing processes between water derived from local infiltration and deep water upflow along tectonic lineaments or anthropogenic water can affect the groundwater balance on a local scale. This study aims to define the potential groundwater origin of one of the highest risk urban landslides in central Italy and to define a hydrogeological conceptual model by exploiting its existing drainage system network. This research is based on a multiple-techniques approach based on hydrological water balance, artificial tracer tests during recharge period, seasonal monitoring of the water stable-isotope content, hydro-chemical survey during low-flow periods, and analysis of the piezometric level fluctuation. All these analyses are coupled with a detailed reconstruction of the geology of the area depicted from boreholes and drill holes. Two groundwater bodies have been evidenced from the study. The shallower one is located in the landslide unstable zone and is hydraulically connected to a deeper groundwater body hosted in the underlying bedrock. Results highlighted that the local rainfall regime could not fully explain the hydro-chemical facies. Local water contributions to the landslide area coming from leakage of the urban sewerage system have been evidenced, excluding deep groundwater upflow from the fault system.

Measuring the environmental performance of urban water systems: a systematic review

Abstract This systematic review aims to understand how previous studies have determined the environmental performance of urban water systems (UWSs) and to identify the main environmental impacts caused by these systems and their respective sources. A systematic review strategy based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was used. The publications were selected by searching the Scopus and Web of Science databases last updated on 8 February 2022 and according to the eligibility criteria that were set for the present study. A total of 25 publications were analyzed in their entirety. Six publications presented methodological contributions by proposing frameworks and models for the analysis of environmental and sustainability parameters of urban water and sewage systems. Nineteen publications conducted case studies where life cycle assessment (LCA) and mass balance methods were employed. The categories of environmental impacts most frequently analyzed in the publications included climate change, eutrophication, acidification, and human toxicity. Moreover, the sources of these negative impacts were identified as high electricity consumption, chemical use, and nutrient discharge into the environment. The present review analyzes the contributions to each stage of the systems that are associated with the characteristics of the systems and the level of detail of the used data.

Operational and structural diagnosis of sewerage and drainage networks in Côte d'Ivoire, West Africa

In Cote d'Ivoire, the failure of urban sewage systems is a crucial problem for the drainage of wastewater and rainwater. This failure is due to many factors and therefore, calls for diagnostic studies. The present study aimed at analyzing these networks in order to identify the different factors that contribute to the operational and structural degradation in selected sewerage and drainage networks in Abidjan, Cote d'Ivoire. The method used in the study involved semi-structured interviews, video camera inspection and socio-environmental field surveys (geographical survey and household survey), followed by descriptive statistics. The results revealed that many structural, environmental and behavioral practice contribute to the progressive degradation of urban sewage systems. These factors are essentially those that prevent the normal flow of wastewater in the pipes such as the illegal dumping of solid waste, the unauthorized connection of wastewater networks, unsustainable urban agricultural practices, as well as the high concentration of vegetation on both sides of the network and the dilapidated infrastructure of the wastewater and rainwater networks. It was found that these factors are at the origin of the clogging and degradation of the sewers since 85% of the residents used these sewers as a dumping ground for solid waste.