Search Results (268)

Rain gardens are widely used for stormwater treatment; however, the performance of alternative sorbent materials under varying rainfall conditions remains insufficiently understood. In this study, the removal of nutrients and heavy metals was evaluated in laboratory-scale rain gardens amended with halloysite of two grain size fractions (1–2 mm and 2–4 mm) under rainfall events lasting 30 and 120 min. Three column systems were tested: a reference column containing dolomite, sand, and gravel (C1), and two halloysite-amended columns (C2 and C3). Synthetic stormwater containing N–NH₄⁺, N–NO₃^–, P–PO₄^3–, Cu, Zn, and Pb was applied. Halloysite improved nutrient removal in all rainfall scenarios compared with the reference column. Dissolved inorganic nitrogen (DIN) removal reached 84% in column C3, whereas soluble reactive phosphorus (SRP) removal reached 85% in column C2. Complete removal of Cu, Zn, and Pb was observed in all columns, highlighting the dominant role of dolomite in heavy metal retention. These findings demonstrate the potential of halloysite as a nutrient-removing amendment in rain garden. Full article

This study presents a photocatalytic infiltration pavement block designed to combine roadside NO_x removal with rainwater capture and temporary storage. TiO₂ and styrene–butadiene rubber (SBR) latex were incorporated into the pavement block to provide photocatalytic functionality, and direct infiltration holes were introduced to capture surface runoff, enable temporary storage, and promote delayed subgrade drainage. The effects of TiO₂ and SBR latex on compressive strength and NO_x removal were evaluated, while rainwater infiltration performance was examined using acrylic panels with different hole diameters, hole-area ratios, slopes, and V-groove treatments. The use of SBR latex improved the compressive strength of TiO₂-containing mixtures, with T10-L5 showing an 8.1% increase compared with the corresponding non-latex mixture. The same mixture achieved the highest NO_x removal efficiency, reaching 73.0% after 60 min of UV exposure. In the infiltration test, the 5 mm hole configuration gave the most stable runoff reduction, and lattice-type V-grooves improved water capture by connecting adjacent holes and guiding surface flow. A field-scale trial installation confirmed that the integrated infiltration–retention system suppressed visible ponding and runoff, provided delayed subgrade drainage, and maintained pavement stability under vehicle loading. The findings indicate that the proposed block system can provide combined air-purification and stormwater-control functions. Full article

The implementation of water reuse strategies requires robust Decision-Support Tools (DSTs) capable of integrating legal, environmental, site-specific, and technological aspects. However, existing approaches are often limited by fragmented methodologies or high data and modelling requirements, restricting their applicability in early-stage planning. This study presents the development and validation of LëtzREUSE, a DST designed to support the selection of treatment technologies for the reuse of urban water sources, including rainwater, stormwater, light greywater, and wastewater treatment plant (WWTP) effluents. The tool is based on a parameter-driven framework that combines (i) regulatory compliance as a first filtering step, (ii) technology applicability defined through operational thresholds linked to water quality parameters, and (iii) prediction of treatment performance along treatment trains. In contrast to multi-criteria approaches, the methodology avoids subjective weighting by directly linking input water quality to process feasibility and expected effluent characteristics. Additionally, ecotoxicological risk is quantified through risk quotient (RQ) reduction, enabling the evaluation of environmental relevance alongside technical performance. The DST was validated using experimental data from the Bleesbruck WWTP, where measured influent characteristics were used to assess the performance of the tool. The results demonstrate that the tool successfully identifies feasible technologies, with Granular Activated Carbon (GAC) + UV (Ultraviolet light) and UV/H₂O₂ + GAC emerging as the most suitable options. By providing the expected quality parameters, both treatment trains can be compared. The final decision should be based on other parameters such as operational complexity. Full article

Traditional urban drainage systems face increasing pressures due to growing urbanization and climate change, which amplify stormwater volumes beyond the design capacity of sewer networks. These conditions often result in combined sewer overflows (CSOs) and wastewater treatment plant (WWTP) bypasses, discharging untreated, nutrient-laden effluents into receiving water bodies. Elevated nitrogen (N) and phosphorus (P) loads from these events exacerbate eutrophication and harmful algal blooms in lakes. The ENVISION project (Lake Pollution: Integrating Nature-Based Solutions Into Environmental Urban Planning for Risk Mitigation) addresses the impact of urban discharges on lakes and evaluates the potential of Nature-Based Solutions (NBSs) to mitigate N and P releases from CSOs. A coupled hydrological–hydraulic and probabilistic modeling framework is applied to the Lake Maggiore (Northern Italy) catchment as a case study, to assess the potential of NBSs in reducing CSO events and, consequently, the N and P loads discharged into the lake. Preliminary results from the hydrological–hydraulic approach are presented. Full article

Pesticide contamination in urban runoff, stormwater, and peri-urban drainage networks is an increasing concern because of the persistence, mobility, and ecological toxicity of many pesticide residues and their transformation products. Nature-based solutions (NBSs), including constructed wetlands, bioretention systems, biofilters, and permeable reactive bio-barriers, provide low-energy and ecologically compatible platforms for urban water treatment; however, their performance is often constrained by limited sorption capacity, substrate saturation, variable hydraulic loading, and incomplete degradation of persistent pesticides. Biochar offers a multifunctional amendment for strengthening these systems because its tunable porosity, surface functionality, mineral composition, redox activity, and microbial habitat-forming capacity can support pesticide adsorption, catalytic transformation, and biodegradation. This review critically evaluates biochar-integrated NBSs for pesticide-contaminated urban water systems by linking biochar production and modification strategies with pesticide removal mechanisms, biochar–microbe interactions, engineered treatment configurations, and field-scale applicability. A comparative synthesis is provided across material-level mechanisms, system-level performance, machine learning-assisted prediction, techno-economic feasibility, life-cycle impacts, and environmental risk considerations. By integrating material properties, removal mechanisms, NBS configurations, predictive modeling, sustainability assessment, and risk considerations, this review provides a broader comparative basis than previous studies focused mainly on individual aspects of biochar-based pesticide remediation. Future priorities include standardized biochar production, long-term field validation, spent-biochar management, ecotoxicological assessment, and data-driven optimization of biochar-assisted NBSs. Full article

Extreme precipitation and compound hazards can increase the risk of inundation and accidental release of untreated effluent from water treatment facilities, with potential downstream impacts within a short emergency-response window. Few studies have linked site-scale surface-runoff behavior, feasible emergency-response scenarios, and resilience-based decision support for critical water infrastructure. This study presents a GIS-based scenario-comparison framework that couples high-resolution surface-runoff simulation with an AHP-informed resilience interpretation to evaluate untreated effluent runoff and temporary flood-defense strategies at a water treatment plant in Jeollabuk-do, South Korea. A 1 m digital elevation model derived from drone-based LiDAR data was used in ArcGIS Pro to simulate two-dimensional unsteady surface-runoff propagation, producing water-depth and flow-velocity fields at 30 s intervals over 20 min. Three scenarios were compared under identical topographic, release, and hydraulic assumptions, no response, primary defense-line deployment, and secondary defense-line deployment, adding a 335 m barrier along the downstream road. Under the no-response scenario, released water reached the river after approximately 6 min, with a cumulative river inflow of 329.27 m³. The primary defense line reduced cumulative river inflow by 16.8%, and the secondary defense line by 78.2%, while delaying river arrival to 8 min and 30 s. An approximate surface-water balance and time-series analysis showed that the defense lines primarily redistribute water into temporary upstream storage rather than eliminate it. The simulation-derived indicators were linked to four resilience components whose relative importance was estimated using the Analytic Hierarchy Process (AHP) from 205 expert and practitioner responses, which identified recovery speed as the highest-priority component; the weighted normalized indicators are summarized as a transparent scenario-level composite resilience indicator that increases from the no-response to the primary and secondary defense-line scenarios. Because the stormwater drainage network, pollutant transport, and operational deployment uncertainties were not explicitly modeled, the results should be interpreted as a comparative assessment of water-volume transport risk rather than a deterministic prediction of inundation or pollution impact. Within these stated assumptions, the results indicate that a strategically placed secondary defense line can substantially reduce downstream river inflow and secure additional response time, providing preliminary decision support for disaster-risk reduction and emergency-response planning at critical water infrastructure. Full article

This study explores the case of the Wuhan East Lake National Independent Innovation Demonstration Zone (East Lake High-Tech Zone), investigating an advanced-scale stormwater and sewage co-treatment system alongside a “low-position, differentiated, vacuum” sewage collection approach. These systems operate within the framework of the “five-builds-one-management” model, which covers sewage collection, treatment, sludge disposal, reclaimed water utilization, tailwater discharge, and operation and maintenance management. The proposed system was associated with measurable before–after improvements: the sewage collection rate increased by 17%, the influent BOD₅ concentration at the sewage treatment plant rose from approximately 92 mg/L to 112 mg/L (~+22%), and water level fluctuations in the tailwater receiving area were reduced by 75%. This planning framework offers a valuable reference for similar urban areas, though calibration based on local hydrological conditions, industrial structure, and population size is essential. Full article

Reclaimed water-receiving rivers face increased hypoxic and malodorous risks after stormwater runoff. To investigate how initial runoff drives the co-variation of pollutants and microbial communities at the sediment–water interface (SWI), this study constructed a four-channel simulated river system based on the Froude similarity criterion, including two low-intensity rainfall (R-L) treatments and two high-intensity rainfall (R-H) treatments. Each experiment consisted of a 48 h runoff disturbance stage followed by a 48 h recovery stage. The dynamics of carbon (C), nitrogen (N), and phosphorus (P) in both water and sediments were systematically analyzed, together with variations in dissolved organic matter (DOM) composition, microbial communities based on 16S rRNA, and predicted N-cycling functional potential. Results showed that R-H exerted a pronounced dilution effect on pollutants in water but significantly enhanced SWI disturbance, facilitating nutrient accumulation within the system. DOM profiles indicated active microbial metabolism, consistent with long-term reclaimed water inputs. Microbial analyses revealed that TN was a key environmental factor influencing community differences. Nitrification and denitrification potentials were higher under R-H, whereas ammonia assimilation was higher under R-L. These findings highlight the importance of managing N accumulation and transformation following rainfall events in reclaimed water-receiving rivers. Full article

The revised EU Urban Wastewater Treatment Directive (UWWTD, EU 2024/3019) expands the scope of the previous directive (Council Directive 91/271/EEC, 1991) by explicitly including combined sewer systems, stormwater discharges, and overflow events while promoting energy neutrality and reducing greenhouse gas (GHG) emissions across urban wastewater systems. Although the Directive establishes energy accountability at the system level, it does not define how energy performance in wastewater collection networks should be structured, assessed, or benchmarked, resulting in a significant implementation gap. This paper presents a novel, regulatory-aligned, data-driven framework to organise, analyse, and interpret energy-relevant information in support of UWWTD requirements, with specific focus on wastewater collection networks. Using Portuguese regulator datasets, supplemented with published sources, existing metrics are reorganised into energy-significant dimensions that differentiate structural, excess-driven, operational, and renewable-related components of energy use. The preliminary findings show that available datasets already support a screening-level diagnosis of specific energy intensity, pumping-related energy shares, inflow-driven excess volumes, and associated GHG emissions. However, important gaps remain regarding subsystem disaggregation, hydraulic normalisation, and measurement granularity. The study restructures existing information into a novel audit-compatible framework, proposes additional metrics and measurement requirements, and identifies measures to facilitate UWWTD implementation. Although developed for the Portuguese context, the framework offers a scalable pathway for integrating wastewater collection networks into energy neutrality governance across European Member States. Full article

Single-species hedges can help mitigate a range of urban and climate change-related issues, such as slowing stormwater flow and reducing rainfall runoff, particularly during the growing season. There is, however, little information on the service delivery of mixed hedges and their comparison to single-species, year-round, as well as on the practicality of functional rather than ornamental plant mixing. Here, we report on an initial case study to address this. Chosen hedge taxa (Crataegus monogyna, Elaeagnus × submacrophylla ‘Gilt Edge’, Ligustrum ovalifolium, Thuja plicata ‘Atrovirens’) represented a range of plant characteristics. These were trialled outdoors in Reading (SE England, UK) as treatment groupings of either single-species or mixed-species (‘evergreen’ and ‘broadleaf’ mix), along with a bare soil control, in 110 L troughs. We applied 5 min simulated rainfall onto each treatment twice in every meteorological season and assessed canopy throughfall. We also monitored substrate moisture content change as a proxy for evapotranspiration and substrate storage capacity of subsequent rainfall. During summer, the deciduous taxa and mixed hedges had the highest evapotranspiration rates, suggesting their potential to influence soil water storage, but in our experimental setup, that did not translate into significant differences in substrate moisture between treatments. During autumn and winter, the single-species Thuja treatment had the highest rainfall interception rate, followed by both mixed species treatments. In winter, canopy and leaf characteristics rather than physiological activity correlated with increased rainfall attenuation. However, by the end of the experiment (spring 2023), Crataegus, Thuja and both mixed hedge treatments had significantly lower throughfall (higher interception) compared to bare soil. We are continuing to test these treatments in a longer-term field experiment. Management of mixed-species hedges for rainfall attenuation is practically achievable, despite some differences in individual species’ growth rates and plant habits. Full article

Household rainwater tanks (HRWTs) have re-emerged globally as a decentralised strategy to address water scarcity, climate variability, and increasing urban water demand. In several jurisdictions, including New South Wales, Australia, rainwater tanks have been chosen to meet the mandatory potable water reduction target in new residential developments for nearly two decades; however, growing evidence indicates persistent underutilisation and variable performance in practice. Despite their recognised benefits in reducing potable water demand, mitigating stormwater runoff, and enhancing urban resilience, the global HRWT research landscape remains fragmented across disciplinary and thematic boundaries. This paper presents a multifaceted review, defined here as an approach that synthesises multiple perspectives on the topic. It integrates systematic mapping of peer-reviewed literature with a critical thematic analysis across four dominant research domains: technological and design innovation, policy and governance frameworks, environmental performance, and social–behavioural dimensions. The findings reveal a strong research focus on technical optimisation, while policy effectiveness, environmental trade-offs, and household-level behavioural factors receive comparatively uneven attention. Regulatory and incentive-based instruments are shown to produce inconsistent outcomes, shaped by local institutional capacity to design, implement, enforce, and sustain programs, as well as by climatic context and household acceptance. Environmental assessments identify both benefits and burdens, including energy use, treatment requirements, and operational complexity. Social and behavioural studies indicate growing acceptance of household rainwater tank (HRWT) systems. However, financial constraints, local conditions, and ongoing maintenance demands continue to influence adoption and performance. A key insight from this review is the limited attention given to households’ lived experiences, particularly how users adopt, adapt, operate, and maintain HRWT systems over time. This gap constrains progress across technical, policy, environmental, and social dimensions and risks cycles of early policy uptake followed by stagnation. The review highlights the need to integrate household perspectives into future research, policy design, and industry practice to improve system performance, user experience, and the long-term contribution of HRWTs to sustainable urban water management. Full article

Hydrodynamic efficiency in wetland systems is governed by the complex interaction between fluid flow and vegetation density. This study quantifies the impact of seasonal emergent vegetation growth on solute transport in a V-shaped flume. Using high-resolution tracer data from high-density (January) and low-density (November) conditions, we characterized hydraulic parameters, longitudinal velocity (v), and dispersion (D), across an upstream conduit (Reach 1) and a downstream retention zone (Reach 2). Results revealed that in January, Reach 2 exhibited massive hydraulic retardation (v ≈ 1.8 cm s⁻¹) and extensive non-Fickian tailing (variance > 30,000 s²), maintaining an idealized retentive state (Pe ≈ 20). Conversely, seasonal biomass reduction in November resulted in lower variance (≈16,500 s²) and drastically increased the risk of extreme advective bypass (Pe > 500). These findings provide critical empirical validation for macro-scale models like the Dynamic Model for Stormwater Treatment Areas (DMSTAs). Specifically, the massive temporal variance observed during the retentive state yielded an empirical Tanks-in-Series value of N ≈ 5.7, directly validating standard DMSTA defaults for dense emergent marshes. Furthermore, the Transient Storage Model (TSM) storage ratio (As/A) offers a quantitative mechanism to penalize modeled void fractions, accounting for vegetative “dead zones.” By integrating these flume-derived metrics, wetland managers can optimize hydraulic designs and improve the prediction of treatment efficiency across seasonal variations. Full article

Urban stormwater runoff often contains toxic metals that threaten aquatic environments. Meanwhile, the large quantities of drinking water treatment residuals (DWTRs) generated worldwide offer opportunities for sustainable reuse as pollutant removal materials. In this study, a manganese sand-modified drinking water treatment residual particle (RDP-M) was prepared from DWTRs and manganese sand for Pb(II) removal from water. Characterization by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) showed that RDP-M had a rough surface morphology and abundant oxygen-containing functional groups, which provided adsorption sites. Batch experiments showed that the maximum Pb(II) adsorption capacity of RDP-M reached 2.79 mg g⁻¹ at 298 K and pH 7.0, which was about 48% higher than that of the unmodified particles (RDP). The adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model, indicating a chemisorption-dominated process. Thermodynamic analysis further showed that the process was spontaneous and exothermic. RDP-M maintained stable Pb(II) removal over a wide pH range, showed low sensitivity to coexisting ions, and retained high efficiency during repeated use. These results demonstrate that RDP-M has potential as a sustainable granular material for stormwater treatment and waste resource valorization. Full article

Water temperature is a key ecological and metabolic factor in rivers and other continental systems, and thermal pollution caused by anthropogenic activities (dams, discharges, urban stormwater, industrial cooling) alters the natural thermal regime of rivers, modifying the structure and functioning of communities (primary producers, macroinvertebrates and fish) and favouring thermophilic and often invasive species. Wastewater treatment plants (WWTPs) generate and discharge excess heat: their effluents are often several degrees above the temperature of the receiving river, which increases the metabolism of communities, favours eutrophication and can intensify the effects of nutrients and toxic pollutants. This excess heat from wastewater is a major renewable energy resource that can be recovered using heat pumps, both in buildings and in the treatment plants themselves, as well as in district heating networks, reducing the demand for fossil fuels and CO₂ emissions. Heat recovery in WWTPs, especially from treated effluent connected to district networks, offers very high technical potential (tens of TWh per year on a national scale in some countries) and can contribute significantly to more sustainable urban energy systems. Heat recovery in WWTPs can minimize the thermal impact of effluents on receiving rivers, reducing the negative effects of discharges on the natural environment. Full article

Emerging contaminants (ECs) are a diversely mounting group of chemicals and biological compounds found in air, water, and soil, which include pharmaceuticals, personal care products, per- and poly-fluoroalkyl substances (PFASs), microplastics, endocrine-disrupting chemicals, and various other industrial compounds. Unlike conventional pollutants, ECs are usually unregulated, found in very small amounts, and can persist and build up in living organisms, resulting in toxic risks for both ecosystems and human health. These contaminants originate from various anthropogenic activities and enter the environment through wastewater, stormwater, landfill leaching, and atmospheric deposition. This article documents a holistic literature review of ECs available from the last five years, covering classification, sources and pathways of contamination, and environmental behavior, while assessing their ecological, human health, and socioeconomic impacts. Advances in detection, including high-resolution mass spectrometry, non-target screening, real-time sensors, and AI-assisted monitoring, are addressed. Management strategies including advanced oxidation, membrane filtration, electrochemical treatments, and nature-based solutions are explored. It also analyses global and regional policy frameworks, highlighting regulatory gaps and the need for standardized monitoring. The study emphasizes integrated, multidisciplinary approaches combining scientific innovation, sustainable chemical design, predictive modeling, and public engagement. Synergizing technology, governance, and prevention could reduce the risks related to ECs and protect the environment. The novel contribution is an end-to-end, decision-oriented synthesis that links what monitoring can reliably infer to be feasible, integrated control strategies and sustainability outcomes, supporting risk-based prioritization, targeted pollution treatment, and prevention-focused management. Full article