Search Results (22)

With the increasing frequency of desilting in urban drainage systems, the safe disposal and resource reuse of sewer sediments have become a prominent practical challenge. Screened sand, the most promising component for resource recovery from sewer sediments, still lacks systematic insight into its pollution risks and the necessity of pretreatment. In this study, 120 raw sewer sediment samples were collected from sanitary, storm, and illicitly connected (IC) storm sewers in Shanghai, alongside seasonal screened sand samples. We systematically characterized their physicochemical properties and heavy metal and antibiotic pollution profiles, and evaluated the purification performance of ultrasonic treatment, sodium hexametaphosphate (SHMP) washing, and their coupled processes. Results revealed significant differences in sediment properties across pipeline types. Screened sand, dominated by SiO₂ and CaO, shows preliminary potential for reuse as a low-grade bulk building material, but its organic loss on ignition (LOI) of 5.29–13.42% exceeded the reuse limit. Concentrations of heavy metals and antibiotics were generally higher in screened sand than in raw sediments, with further enrichment in the fine sand fractions, indicating that screening only redistributed contaminants rather than eliminated them. The coupled ultrasonic–SHMP process, applied for the first time to screened sand from sewer sediments, achieved optimal performance, with a maximum LOI reduction and over 85% removal of certain antibiotics, without damaging the sand’s mineral skeleton. This study provides a scientific basis for the safe resource reuse of screened sand. Full article

Antimicrobial resistance (AMR) in hospital wastewater is a recognized public health concern, yet the dynamics of its emergence remain poorly understood. This study aimed to characterize the quantitative and qualitative changes in the microbial community of a newly built internal medicine intensive care hospital wing following the start of patient treatment. Wastewater samples were collected regularly from eight relevant sites, including seven patient-associated locations within the intensive care ward and the central sanitary sewer where all effluent converged. Culture-based analyses targeted the “ESCAPE-SO” bacterial and fungal groups (“Enterococci”, “Staphylococci”, “Candida”, “Acinetobacter”, “Pseudomonas”, “Enterobacteriaceae”, “Stenotrophomonas”, “Others”). Comparisons were made between a 12-month pre-operation period (only flushing every 72 h to prevent contamination of the drinking water system) and the first 12 months of patient treatment. The results showed a significant increase in mean bacterial concentrations from 53 [0–349] CFU/mL before patient treatment to 8423 [3054–79,490] CFU/mL during patient treatment (p = 0.0224) with a particular focus on Pseudomonas spp. as the dominant genus. Resistance against all four main antibiotic classes of the WHO AWaRe essential “watch” list (carbapenems, third-generation cephalosporins, broad-spectrum penicillin and ciprofloxacin) emerged within the first twelve months and depended on the amount of prescribed antibiotics and the number of patients treated. These findings indicate that hospital activity drives rapid development of antimicrobial resistance in wastewater microbial communities, highlighting the critical role of clinical antibiotic use in shaping environmental resistomes. This study provides quantitative evidence that resistance can emerge within months of hospital operation, emphasizing the need for early monitoring and targeted interventions to mitigate the spread of AMR from hospital effluents into broader environmental systems. Full article

This article deals with the design of a technically, legislatively, and economically balanced sewerage system for the municipality of Ropice, which has long lacked a central sanitary sewer system. On the basis of the analysis of the territorial conditions, hydro-technical calculations, and legislative requirements, two potential solutions are compared—a decentralized domestic WWTP and a central separate sewerage system with a treatment plant. The final concept favors the central solution in order to ensure operational reliability, sustainability, and the possibility of using grants. This study provides a model example of an applicable solution for rural settlements with similar wastewater management problems. Full article

Fats, oils, and grease (FOG) deposits are hardened, sticky, insoluble solids that accumulate in sewage systems globally. These deposits contribute to pipe blockages and sanitary sewer overflows, releasing pathogens and pollutants into the environment, posing significant environmental and public health risks. Current removal methods are labor-intensive and costly, emphasizing the need for alternatives. While biological strategies offer a viable alternative, the microbial breakdown of FOG is poorly understood. In this study, we evaluated the potential of individual microbial strains and synthetic microbial communities to biodegrade wastewater-derived FOG deposit samples. These biological agents were applied to a range of FOG samples, and biodegradation was assessed through visual observations such as color change or gas bubbles, particle size, cell counts, pH, weight loss, and changes in fatty acid profile. Results demonstrate that microbial augmentation can enhance FOG degradation, offering an alternative or complementary approach for reducing maintenance burdens and preventing sewer blockages. Full article

Pressure on fresh water resources has been aggravated in recent decades, basically due to population growth, rapid urbanization, and global warming. Integrated engineering solutions and the circular economy, considering the urban water cycle as a whole, are becoming fundamental, particularly in arid and semi-arid regions under permanent or recurrent hydric deficit. This study aims to develop and present an integrated engineering solution for water supply, wastewater collection, and treated wastewater reuse for landscape irrigation in a large, topographically complex, and arid to semi-arid coastal urban region at the south of Santiago Island, Cape Verde. The region is one of the driest and most arid of the Island, with a current average annual precipitation between about 100 and 200 mm, and has very limited underground water resources. The main study area, with about 600 ha, has altitudes ranging from values close to sea level up to about 115 m and has several topographic difficulties, including several relatively rugged zones. The devised water supply system considers four altimetric distribution levels, three main reservoirs connected to each other by a serial system of pipelines with successive pumping, a fourth downstream reservoir for pressure balance in one of the levels, and desalinated water as the source. The sanitary sewer pipes of the urbanizations drain to an interceptor system that operates predominantly in open channel flow in a closed pipe. The long interceptor crosses laterally along the coast several very dug valleys in the path to the Praia Wastewater Treatment Plant in the east, and requires several conduits working under pressure for the crossings, either lifting or governed by gravity. The under-pressure pipeline system of recycled water is partially forced and partially ruled by gravity and transports the treated wastewater from the plant in the opposite direction of the interceptor to a natural reservoir or lake located in the region of urbanizations and the main green spaces to be irrigated. The conceived design of the interceptor and recycled water pipeline minimizes the construction and operation costs, maximizing their hydraulic performance. Full article

Urban sewer conditions assessment is important for the proper conveyance of sanitary water to wastewater treatment plants prior to environmental discharge. An effective approach to address this important process needs to be developed. This paper presents a data-driven methodology for sewer condition assessment with gridding-based chemical markers measurement in combination with a Bayesian chemical mass balance (CMB) model. A field study was performed in an urban sewer in Nanjing, China, to test the robustness of the developed methodology. In this site, data library of chemical markers (total nitrogen, phosphate, chloride, and total hardness) for source flows, including domestic wastewater, commercial wastewater and groundwater, was established. Meanwhile, a gridding-based measurement of these chemical markers in sewer flows was performed along the assessed sewer. Then, the CMB model with Bayesian inference and parallel Markov Chain Monte Carlo simulations was developed to quantify source contributions in sewer flows based on the chemical markers data of source and sewer flows. Accordingly, the proportion of clean water infiltration into the sewer and associated sewer defect level can be assessed. The Bayesian CMB model presented that groundwater contributed 11~14% of the sewer flow, indicating a neglectable sewer defect condition. The sewer assessment result was further verified by on-site physical inspection with distributed temperature sensing of in-sewer flows, proving the reliability of the developed methodology. Using this data-driven approach, a preliminary screening of the high-risk sub-catchments with severe sewer defect levels can be made for the following targeted sewer defects locations, optimizing the labor-intensive, system-wide physical inspections. Therefore, the proposed approach offers a cost-effective solution for system-wide sewer inspections. Full article

The wastewater conveyance systems in the United States are facing severe structural challenges, with the nation’s overall wastewater infrastructure receiving a critically low grade of D- from the American Society of Civil Engineers (ASCE). Innovative trenchless technologies, such as Cured-in-Place Pipe Renewal Technology (CIPPRT), offer a cost-efficient substitute for traditional open-cut construction methods (OCCM). However, the possibility of a comprehensive life-cycle cost analysis (LCCA) comparing these methods remains unexplored. LCCA examines the comprehensive financial impact, encompassing installation, operation, maintenance, rehabilitation, and replacement expenses, using net present value (NPV) over a set duration. The objective of this study is to systematically review the existing literature to explore advancements in calculating the LCCA for CIPPRT and compare the latter approach to OCCM. A rigorous PRISMA-guided methodology applied to academic databases identified 845 publications (1995–2024), with 83 documents being selected after stringent screening. The findings reveal limited use of artificial intelligence (AI) or machine learning (ML) in predicting CIPPRT costs. A bibliometric analysis using VOSviewer visualizes the results. The study underscores the potential of intelligent, data-driven approaches, such as spreadsheet models and AI, to enhance decision-making in selecting rehabilitation methods tailored to project conditions. These advancements promise more sustainable and cost-effective management of sanitary sewer systems, offering vital insights for decision-makers in addressing critical infrastructure challenges. Full article

Onsite wastewater treatment systems (OWTSs or septic systems), when properly sited, designed, operated, and maintained, treat domestic wastewater to reduce impacts on and maintain sustainability of aquatic resources. However, when OWTSs are not performing as expected, they can be a potential source of human fecal pollution to recreational waters, resulting in an increased risk of illness to swimmers. Quantifying the contribution of poor-performing OWTSs relative to other sources of fecal pollution is particularly challenging in wet weather when various sources commingle as they flow downstream. This study aimed to estimate the total load of human fecal pollution from OWTSs in an arid watershed with municipal separate storm sewer systems (MS4). The novel study design sampled HF183, a DNA-based human marker, from six small catchments containing only OWTSs and no other known human fecal sources, such as sanitary sewer collection systems or people experiencing homelessness. Then, the human fecal loading from the representative catchments was extrapolated to the portions of the watershed that were not sampled but contained OWTSs. Flow-weighted mean HF183 concentrations ranged from 10⁴ to 10⁷ gene copies/100 mL across 29 site-events. HF183 mass loading estimates were normalized to the number of parcels per catchment and inches of rainfall per storm event. Assuming the normalized loading estimate was representative, extrapolation to all of the OWTS parcels in the watershed and average annual rainfall quantity illustrated that HF183 loading from OWTSs was a small but measurable fraction of the total HF183 mass loading emanating at the bottom of the watershed. Clearly, other human fecal sources contributed HF183 during storm events in this watershed. The loading estimate approach used in this study could be applied to other watersheds facing similar challenges in prioritizing resources for monitoring and mitigation among co-located human fecal sources. Full article

A deficiency in accurate and current regulations, along with a lack of experience in sanitary construction, makes the installation of sewers challenging. Using models, it was determined that if the pumps were operated simultaneously, the service would last for a long time over the entire sewer system. With a daily sewage inflow of 468 dm³, the system was found to run 14.4–14.7% longer than expected at 100 pumping stations. Each month, the pressure-sensitive sewer system receives more than 51 min of extended service from the city’s central sewer system. Increasing wastewater inflow and the number of pumps decrease centrifugal pump capacity. In the study, the main findings were related to the number of pumps. With 100 centrifugal pumps simultaneously, the pressure-based system was most effective. An increase in operation time of 18.4–19.1% was observed over a period of 30 days and an average sewage inflow of 705 dm³ for each. In place of gravity sewerage, sewerage can be used. Pressure sewer systems should be designed in a way that addresses technical as well as economic concerns. Accordingly, this study indicates that pressure sewerage is a viable alternative to gravity sewerage in villages with scattered drinking water supplies. Full article

Wastewater collection, transport, and treatment systems are essential to ensure human and environmental well-being. The Escuela Superior Politécnica del Litoral (ESPOL), has been implementing various sanitary sewerage systems; however, population growth has given rise to discussion on the installed capacity versus the necessary capacity for the future population in the sustainable management of water resources. Therefore, this study aimed to develop a sanitary sewerage master plan by analysing the existing situation and applying technical criteria for the sustainable use of wastewater on a university campus. The methodology consisted of (i) evaluation and diagnosis of the area studied through data collection and processing, (ii) design of the sanitary sewerage system considering area-expansion zones, and (iii) SWOT analysis of a proposal to enhance wastewater transport and treatment systems. The proposal contemplates designing a sanitary sewer system that will manage the collection, transport, and treatment of wastewater over 15 years for 5667 inhabitants located in three expansion zones with occupation periods of 5, 10, and 15 years. The sewerage system comprises a pipe network 1.19 km long and 200 mm in diameter, transporting 12.37 L/s of wastewater generated to two treatment systems that guarantee efficient depuration and subsequent reuse. This design was complemented by a SWOT analysis of the existing sanitation system developed by experts in the area, which included optimising existing treatment systems and reusing wastewater for irrigation of green areas as tertiary treatment within the circular economy. The methodology used in the study allows us to offer a tool for efficiently managing wastewater on a university campus, guaranteeing human well-being, and promoting the circular economy of water. Full article

The WHO/UNICEF Joint Monitoring Program (JMP) for Water Supply, Sanitation and Hygiene (WASH) produces global estimates of the real situation of access to water, sanitation and hygiene services, and sanitation and hygiene in households, educational institutes and health care facilities; however it is lacking data on schools in Kazakhstan. Thus, the aim of this research was to assess access to WASH in schools of urban area in Kazakhstan. The study was conducted in seven schools of Central Kazakhstan during the COVID-19 pandemic and restrictive measures. Three data collection methods were used: a questionnaire for administrative staff, a questionnaire for parents and observation. Parents of offline study pupils (only second and third grades due to the pandemic) were included in the survey. Students had access to in-building toilets in all schools connected to the centralized sewer. The number of school toilets varied from 7 (KAZ200085) to 61 (KAZ200089). The average amount of toilets was 28.08 ± 16.97. Only two out of seven schools complied with the requirements of Kazakhstan national sanitary standards for the ratio of school toilets to the number of students. From the questionnaire with the school administrations, it was defined that the primary source of drinking water was the public water supply. All schools regularly disinfect and check the water supply system. At the same time, the results also revealed discrepancies in the answers between administration and parents (2.6% of parents showed that their children have rare access to drinking water), and insufficient monitoring of implementation of WASH services. This study also confirmed that the full provision of access to water and water services in the structure of educational institutions solves several SDG targets. Full article

Sanitary sewer pipes infrastructure system being in good condition is essential for providing safe conveyance of the wastewater from homes, businesses, and industries to the wastewater treatment plants. For sanitary sewer pipes to deliver the wastewater to the treatment plants, they must be in good condition. Most of the water utilities have aged sanitary sewer pipes. Water utilities inspect sewer pipes to decide which segments of the sanitary sewer pipes need rehabilitation or replacement. The process of inspecting the sewer pipes is described as condition assessment. This condition assessment process is costly and necessitates developing a model that predicts the condition rating of sanitary sewer pipes. The objective of this study is to develop Multinomial Logistic Regression (MLR) and Artificial Neural Network (ANN) models to predict sanitary sewer pipes condition rating using inspection and condition assessment data. MLR and ANN models are developed from the City of Dallas’s data. The MLR model is built using 80% of randomly selected data and validated using the remaining 20% of data. The ANN model is trained, validated, and tested. The significant physical factors influencing sanitary pipes condition rating include diameter, age, pipe material, and length. Soil type is the environmental factor that influences sanitary sewer pipes condition rating. The accuracy of the performance of the MLR and ANN is found to be 75% and 85%, respectively. This study contributes to the body of knowledge by developing models to predict sanitary sewer pipes condition rating that enables policymakers and sanitary sewer utilities managers to prioritize the sanitary sewer pipes to be rehabilitated and/or replaced. Full article

Composite materials have become synonymous with modernity, desired in nearly every aspect of our daily lives, from simple everyday objects to sanitary facilities, pipelines, the construction of modern sewer networks, their renovation, water supply, and storage reservoirs, to complex structures—automotive, planes, and space science. Composites have seen a considerable rise in attention owing to their characteristics, durability, strength, reduced energy usage during the manufacturing process, and decreased transportation costs. Composite materials consistently outperform steel, cast iron, and concrete in terms of CO₂ emissions. Additionally, these materials have a long service life of about 150 years or more and are corrosion-resistant. Today, continued sustainable development is contingent upon access to safe drinking water and the availability of its resources and modes of conveyance. As a result, composite pipes have considerable potential due to their very low flow rate, which directly affects the prices of drinking water pumping and irrigation systems. However, there are also certain disadvantages associated with fibre-reinforced composites, such as easy surface damage, low heat resistance (up to 220 °C), long product forming time, and high cost of the material. Additionally, the product’s initial high durability and extended life cycle, coupled with high abrasion resistance, anisotropic strength, and stiffness in the final phase, prove to be unfavourable since composite material cannot be rapidly reintroduced into the manufacturing cycle. However, its disposal requires a negligible amount of energy. The article discusses the various composite materials available, their applications, and the potential for further developing their manufacturing technology toward nanocomposites and composites of natural origin that are readily biodegradable at the end of their service life; dubbed “green composites”. The study’s findings are unequivocal: this class of composite materials warrants further investigation in the future since they align perfectly with the concept of sustainable economic growth and Green Deal implementation. Full article

In the urban drainage system, the formation of sewer sediments is inevitable, and the removal of sewer sediments is necessary for system maintenance. Disposal of arisings from sewer sediment removal is becoming a serious environmental issue. The current knowledge of sewer sediments is limited, which is restrained to sewer sediments management. To better understand this municipal waste, the sewer sediments of a combined sewer system in Longgang District, Shenzhen were collected and characterized, and the spatial distribution characteristics of contaminants were analyzed. Based on the bivariate correlation analysis, it is found that many contaminants in sewer sediments have a strong relationship with spatial variables. Compared to the sewer sediments in industrial areas, those in residential areas contain higher concentrations of Hg and phosphorus. The sediments in the sewage conduit also contain more organic matter (OM), phosphorus, Cu, and Ni, and the sediments in the rainwater conduit contain a higher concentration of Cd. Moreover, the sediments produced in different catchments also show huge differences in the content of contaminants. These spatial distribution characteristics may provide help for the further classification of sewer sediments, thereby making the disposal of sediments more targeted. According to the local standards of sludge disposal, land application and incineration are not suitable for managing sewer sediments due to the low OM content and poor lower heating value (LHV). Although sanitary landfill is feasible for sewer sediments disposal, the complicated composition of sewer sediments still poses the risk of polluting the surrounding environment. The management of sewer sediments via the production of building materials is a promising technical route that can avoid the migration of hazardous contaminants and produce valuable products. This study may improve our understanding of sewer sediments and provide a reliable recommendation for sewer sediment management. Full article

Hydrogen sulfide (H₂S) related to wastewater in sewer systems is known for causing significant problems of corrosion and odor nuisance. Sewer systems severely affected by H₂S typically rely on online H₂S gas sensors for monitoring and control. However, these H₂S gas sensors only provide information about the H₂S emission potential at the point being monitored, which is sometimes inadequate to design control measures. In this study, a comparison of three market-ready online sensors capable of liquid-phase H₂S detection in sewer systems was assessed and compared. Two of the three sensors are based on UV/Vis spectrophotometry, while the other adapted the design and principles of a Clark-type electrochemical microsensor. The H₂S measurements of the sensors were statistically compared to a standard laboratory method at first. Following that, the performance of the online sensors was evaluated under realistic sewer conditions using the Berlin Water Company (BWB) research sewer pilot plant. Test applications representing scenarios of typical H₂S concentrations found in sulfide-affected sewers and during control measures were simulated. The UV/Vis spectrometers showed that the performance of the sensors was highly dependent on the calibration type and measurements used for deriving the calibration function. The electrochemical sensor showed high sensitivity by responding to alternating anaerobic/anoxic conditions simulated during nitrate dosing. All sensors were prone to measurement disturbances due to high amounts of sanitary solids in wastewater at the study site and required continuous maintenance for reliable measurements. Finally, a summary of the key attributes and limitations of the sensors compared for liquid phase H₂S detection is outlined. Full article