Stormwater Quality Improvement Research Articles

Soil-sediment connectivity through Bayesian source tracking in an urban naturalised waterway via microbial and isotopic markers

Riverine sediments are important habitats for microbial activity in naturalised waterways to provide potential ecosystem services that improve stormwater quality. Yet, little is known about the sources of these sediment microbes, and the factors shaping them. This study investigated the dominant source of sediments in a tropical naturalised urban waterway, using two Bayesian methods for microbial and isotopic 13C/15N markers concurrently. Additionally, key factors shaping microbial communities from the surrounding landscape were evaluated. A comprehensive two-year field survey identified source land covers of interest based on topology and soil context. Among these land covers, riverbanks were the dominant source of sediments contribution for both edaphic and microbial components. The physico-chemical environment explains most of the variation in sediment communities compared to inter-location distances and microbial source contribution. As microbes provide ecosystem services important for rewilding waterways, management strategies that establish diverse sediment microbial communities are encouraged. Since riverbanks play a disproportionately important role in material contribution to sediment beds, management practices aimed at controlling soil erosion from riverbanks can improve overall functioning of waterway systems.

Mechanisms and Applications of Nature-Based Solutions for Stormwater Control in the Context of Climate Change: A Review

Nature-based solutions (NbSs) are considered to form an innovative stormwater management approach that has living resolutions grounded in natural processes and structures. NbSs offer many other environmental benefits over traditional grey infrastructure, including reduced air pollution and climate change mitigation. This review predominantly centers on the hydrological aspect of NbSs and furnishes a condensed summary of the collective understanding about NbSs as an alternatives for stormwater management. In this study, which employed the CIMO (Context, Intervention, Mechanism, Outcome) framework, a corpus of 187 NbS-related publications (2000–2023) extracted from the Web of Science database were used, and we expounded upon the origins, objectives, and significance of NbSs in urban runoff and climate change, and the operational mechanisms of NbSs (including green roofs, permeable pavements, bioretention systems, and constructed wetlands), which are widely used in urban stormwater management, were also discussed. Additionally, the efficacy of NbSs in improving stormwater quality and quantity is discussed in depth in this study. In particular, the critical role of NbSs in reducing nutrients such as TSS, TN, TP, and COD and heavy metal pollutants such as Fe, Cu, Pb, and Zn is emphasized. Finally, the main barriers encountered in the promotion and application of NbSs in different countries and regions, including financial, technological and physical, regulatory, and public awareness, are listed, and future directions for improving and strategizing NbS implementation are proposed. This review gathered knowledge from diverse sources to provide an overview of NbSs, enhancing the comprehension of their mechanisms and applications. It underscores specific areas requiring future research attention.

Eco-friendly green roof from biodegradable substrate for stormwater quality improvement

Currently, there is a significant surge of interest in green roof technology for construction buildings due to its numerous environmental benefits, such as stormwater management, energy efficiency, and enhanced urban biodiversity. However, the issue of potential pollutant release from green roof substrates into runoff water, causing water pollution, needs to be addressed. To tackle this concern, a lab-scale green roof model was assessed, utilizing a biodegradable substrate made from banana peels and eggshell waste (organic fertilizer). Three models were tested: a conventional green roof (control), a green roof with chemical fertilizer, and a green roof with organic fertilizer. Various water quality parameters, including pH, total suspended solids (TSS), nitrogen, phosphorus, and potassium (NPK), and chemical oxygen demand (COD), were evaluated. The results demonstrated the effectiveness of organic fertilizer in reducing TSS and COD levels, where the eco-friendly green roof with biodegradable substrate exhibited an impressive performance, achieving a higher COD removal percentage (78%) compared to the green roof with chemical fertilizer (50%). The utilization of organic fertilizer led to an enhancement in the quality of stormwater runoff, resulting in NPK removal percentages ranging from 17% to 25%. Additionally, the organic fertilizer fostered healthier vegetation growth, leading to a greater number of leaves compared to the chemical fertilizer. These findings highlight the potential of eco-friendly green roofs as a sustainable and effective tool for stormwater management, provided suitable substrate materials are employed.

Integrating the Spatial Configurations of Green and Gray Infrastructure in Urban Stormwater Networks

AbstractGreen infrastructure (GI) practices improve stormwater quality and reduce urban flooding, but as urban hydrology is highly controlled by its associated gray infrastructure (e.g., stormwater pipe network), GI's watershed‐scale performance depends on its siting within its associated watershed. Although many stormwater practitioners have begun considering GI's spatial configuration within a larger watershed, few approaches allow for flexible scenario exploration, which can untangle GI's interaction with gray infrastructure network and assess its effects on watershed hydrology. To address the gap in integrated gray‐green infrastructure planning, we used an exploratory model to examine gray‐green infrastructure performance using synthetic stormwater networks with varying degrees of flow path meandering, informed by analysis on stormwater networks from the Minneapolis‐St. Paul Metropolitan Area, MN, USA. Superimposed with different coverage and placements of GI (e.g., bioretention cells), these gray‐green stormwater networks are then subjected to different rainfall intensities within Environmental Protection Agency's Storm Water Management Model to simulate their hydrological benefits (e.g., peak flow reduction, flood reduction). Although only limited choices of green and gray infrastructure were explored, the results show that the gray infrastructure's spatial configuration can introduce tradeoffs between increased peak flow and increased flooding, and further interacts with GI coverage and placement to reduce peak flow and flooding at low rainfall intensity. However, as rainfall intensifies, GI ceases to reduce peak flow. For integrated gray‐green infrastructure planning, our results suggest that physical constraints of the stormwater networks and the range of rainfall intensities must be considered when implementing GI.

Assessing the effectiveness of site real-time adaptive control for stormwater quality control

Urban sprawl, excessive rainfall, and resource limitations have challenged the performance of conventional water-sensitive urban designs (WSUD). To address these issues, there is a growing interest in adopting site real-time adaptive control (SRAC) for integrated and real-time water management. This research evaluates the effectiveness of SRAC technology in reducing stormwater pollutants in a highly developed urban area, comparing it with conventional WSUD methods. The study focuses on examining the impact of the SRAC-WSUD method on stormwater quality. Findings indicate that the SRAC-WSUD method reliably reduces stormwater pollutants under varying rainfall conditions. Moreover, it enhances the resilience and performance of existing stormwater systems without the need for additional infrastructure upgrades. For the whole year scenario, the SRAC-WSUD method resulted in reductions in total pollutant loads. Notably, there was a 196.72 kg/year decrease in total suspended solids (TSS), a 0.07 kg/year decrease in total phosphorus (TP), and a 0.78 kg/year decrease in total nitrogen (TN). These findings highlight the potential of SRAC-WSUD in improving stormwater quality and its implications for sustainable urban water management. Overall, this research contributes to advancing the understanding and practical implementation of SRAC technology in stormwater management, offering valuable insights for urban planning and water resource preservation.

Green engineered mulch for phosphorus and metal removal from stormwater runoff in bioretention systems

Phosphorus and metals in stormwater runoff are major causes of water quality degradation. Bioretention systems are increasingly implemented to improve stormwater quality and to better manage stormwater quantity. Many studies have focused on modifying the composition of the soil bed to improve pollutant removal. However, the pollutant removal performance of bioretention systems can diminish over time, such as when clogging of the media occurs. Sediment accumulation on the soil surface may inhibit infiltration into the soil bed, thus limiting pollutant removal. Soil replacement may be eventually required as pollutants accumulate in the soil. In this study, a green retrofit material, called green engineered mulch (GEM), was generated by coating regular wood mulch with aluminum-based water treatment residuals (WTR) via a simple and low-energy process (patent pending). The GEM was developed to serve as a green retrofit for bioretention systems to enhance the removal of phosphorus and metals from stormwater runoff. The GEM was placed in a rain garden in Secaucus, NJ, USA for 15 months, during which 12 storm events (ranging from 6.0 mm to 89.6 mm) were monitored. Runoff and infiltrate samples were analyzed for dissolved and total concentrations of phosphorus and metals, along with other key water quality parameters. The GEM significantly reduced (p < 0.05) the total concentrations of phosphorus and metals in stormwater infiltrate compared to the inlet, unlike the regular mulch. Minimal or no contact with the GEM resulted in no significant pollutant removal from surface runoff. No significant pollutant export from the GEM was observed. The spent GEM can be disposed of as non-hazardous waste in municipal landfills. This study demonstrates that the GEM is a safe and effective retrofit. Moreover, the GEM is a simple and economical retrofit solution that can be used in place of regular mulch in bioretention systems.

Overview of the (Smart) Stormwater Management around the Baltic Sea

In this review paper, we investigate the management of the quality of stormwater in the Baltic Sea region. Current stormwater management practices, standards, and legislation do not accurately depict stormwater quality, resulting in an underestimation of its environmental impact. The digitalization and harmonization of stormwater management through the implementation of e-monitoring (online or continuous monitoring) allow for the collection of data. This data can be used to improve stormwater quality and quantity management, thereby reducing the environmental harm induced by anthropogenic activities. Based on the literature review, supporting tables and matrices are proposed to assist decision-makers and other interested parties in developing and implementing “smart” stormwater management solutions. In this article, we demonstrate that such systems can enhance stormwater management and system performance by leveraging data-driven operation and maintenance. Another advantage of the approach is that it contributes to a healthier urban environment and ecosystem well-being.

Mitigation of nutrient leaching from bioretention systems using amendments

Bioretention systems have been showcased to be effective in reducing stormwater quantity and improving stormwater quality. However, the systems can also leach nutrients especially during their initial operation, which needs to be mitigated to optimize their benefits. To examine the efficiency of six amendments selected primarily for reducing phosphorus (P) leaching, six amended and two control cells were constructed and monitored soon after their construction in the field of the 2020 growing season. The effects of the amendments on both the hydrological performance (in terms of water retention rate (WRR)) and water quality performance (in terms of the event mean concentration and pollutant removal rate) were investigated. The results showed that all amendments had the capability of preventing or mitigating P leaching from bioretention systems to varying degrees, with the water treatment residual (WTR) outperforming all other amendments, followed by the activated aluminum (AA) and sorptiveMEDIA (SM) amendments. In addition, some of the amendments (i.e., drywall (DRY), WTR, and SM) were also found to be beneficial in reducing the nitrogen (N) leaching to a slight degree, whereas eggshell (EGG) introduced an extra source of N leached. Furthermore, the temporal evolution of the P leaching of the amendment cells was found to be different from that of the control cells. The same result was not observed for the temporal evolution of the N leaching, implying that the amendments (except EGG) did not largely affect the N leaching. Among the amendments’ effect on WRR, there was no obvious difference. Whereas the observed differences between the control cells and some amendment cells in vegetation growth and antecedent media moisture condition might imply their potential impacts on the hydrologic performance. Overall, other than P leaching, the use of amendments affected other functions of bioretention systems, which should be taken into consideration when selecting an amendment for practice.

Comparison of urban stormwater plant biofilter designs for nutrient and metal removal in South Africa

Abstract This paper presents a comparison of six plant biofilter designs for urban stormwater quality improvement and reports on their performances. Thirty-six columns were populated with the endemic South African plant Prionium serratum, representing plant biofilter designs that incorporate different pollutant removal mechanisms in the biofiltration process. The experimental biofilter columns were subjected to low, typically observed and high urban nutrient and metal synthetic stormwater pollution for five months. Significant loads of NH3-N and dissolved Cd, Pb and Zn were removed, whereas removal of -N, -P and dissolved Cu was more variable. The most efficient design was found to include standard plant biofiltration techniques with upflow filtration, plenum aeration and a saturated zone supporting anaerobic microbial activity. It was found that the most efficient design removed on average 96% of urban stormwater nutrient and metal loads.

Comparison of Selected Agro-Based Filter Media for Stormwater Quality Improvement

Polluted stormwater has become a severe problem in the environment as the runoff collecting various contaminants before discharged into water bodies, degrading the water quality and risking aquatic life. This study aims to evaluate selected agro-based filter media to treat stormwater through environmental laboratory works. These include kernel shell, coconut husk, coconut shell, durian shell, sugarcane bagasse, and pineapple leaves. The stormwater samples used were collected from a pond in Universiti Malaysia Sabah, whereas the filter column is configured through a combination of 80% of agro-based media and 20% of aggregate. Filter performance is evaluated for turbidity, pH, dissolved oxygen, biochemical oxygen demand, and ammoniacal nitrogen. Overall, the findings show the potential in utilizing agro-based media, particularly the shell-based media of CS300, KS300, and DS200. Further investigations are recommended to further study the application of agro-based media in improving the quality of stormwater.

Exploring links between ownership, governance and condition of stormwater quality improvement devices

Local government uses the development approval process to place responsibility for stormwater treatment with private landholders through the installation of stormwater quality improvement devices on their land. This source control strategy can complement publicly owned and managed centralized solutions to improve urban water quality outcomes. The maintenance of decentralized solutions for waterway health is compromised by the motivation of individuals whose professed value of cleaner waterways is not evident in their individual lot-based actions. This exploratory research makes four policy and governance observations: waterway policy should consider property scale and ownership type when allocating responsibility for stormwater treatment; devices need to be integrated within the landscape and be publicly visible; education and regulation are advised in order to better support devices placed in private ownership; and policy will be more likely to achieve cleaner waterways if it aligns the motivations of waterway scientists, maintenance actors and property owners.

Copper and Zinc as Roofing Materials—A Review on the Occurrence and Mitigation Measures of Runoff Pollution

Stormwater runoff from metal roofs has been a significant subject of discussion, especially when it comes to its treatment and the target concentrations that need to be achieved prior to discharge into the aquatic environment. To raise further awareness on this issue, occurrence, characterization, and also mitigation measures for metal roof runoff were analyzed using the example of copper and zinc roofs. These stormwater runoffs were found to contain metals in significant concentrations, mainly due to the wash-off of corrosion products by precipitation. Factors influencing metal corrosion and runoff concentrations were compiled. As Cu and Zn mainly occur in dissolved and thus bioavailable forms in roof runoff, harmful effects on the environment were detected. Therefore, adequate treatment of the runoff before discharge to groundwater or surface water is necessary to protect the aquatic environment. Vegetated infiltration swales as an sustainable urban drainage system enable a reduction in pollution loads. However, especially in densely built-up urban areas, stormwater quality improvement devices (SQIDs) offer an attractive alternative for pre-treating metal roof runoff, as they are mostly located underground. There is not yet a uniform legal approval system for SQIDs in Germany, but the German state of Bavaria has approved four types of SQIDs according to its own developed test criteria.

Assessment of and Solutions to the Stormwater Management System of Auburn University Campus in Auburn, Alabama

Stormwater management needs attention as it causes surface flooding and pollution of nearby waterbodies. Parkerson Mill Creek in Auburn University, which gets polluted through surface runoff, is an example of this. In this study, a Personal Computer Stormwater Management Model (PCSWMM) was used to determine the susceptibility of the existing stormwater network to flooding on the Auburn University campus. Maximum water velocity mapping was used to identify areas associated with 3 categories of velocity (high, medium, and low) to find areas of potential erosion. Among the various sustainable stormwater management initiatives, it was found through a literature review that bioretention cells had the greatest potential to improve stormwater quality by screening pollutants from runoff water as well as minimizing erosion by reducing surface water velocity. Suitability analysis for bioretention cells identified 8 areas on the campus where bioretention cell could be installed for the most effective stormwater management. This study highlights the usability of PCSWMM models and techniques in increasing the efficiency of the stormwater system in any locality.

Characterizing the Stormwater Runoff Quality and Evaluating the Performance of Curbside Infiltration Systems to Improve Stormwater Quality of an Urban Catchment

The conveyance of stormwater has become a major concern for urban planners, considering its harmful effects for receiving water bodies, potentially disturbing their ecosystem. Therefore, it is important to characterize the quality of catchment outflows. This information can assist in planning for appropriate mitigation measures to reduce stormwater runoff discharge from the catchment. To achieve this aim, the article reports the field data from a typical urban catchment in Australia. The pollutant concentration from laboratory testing is then compared against national and international reported values. In addition, a stochastic catchment model was prepared using MUSIC. The study in particular reported on the techniques to model distributed curbside leaky wells with appropriate level of aggregation. The model informed regarding the efficacy of distributed curbside leaky well systems to improve the stormwater quality. The results indicated that catchment generated pollutant load, which is typical of Australian residential catchments. The use of distributed storages only marginally improves the quality of catchment outflows. It is because ability of distributed leaky wells depended on the intercepted runoff volume which is dependent on the hydrological storage volume of each device. Therefore, limited storage volume of current systems resulted in higher contributing area to storage ratio. This manifested in marginal intercepted volume, thereby only minimum reduction in pollutant transport from the catchment to outlet. Considering strong correlation between contributing impervious area and runoff pollutant generation, the study raised the concern that in lieu of following the policy of infill development, there can be potential increase in pollutant concentration in runoff outflows from Australian residential catchments. It is recommended to monitor stormwater quality from more residential catchments in their present conditions. This will assist in informed decision-making regarding adopting mitigations measures before considering developments.

Microbial retention and resistances in stormwater quality improvement devices treating road runoff.

Current knowledge about the microbial communities that occur in urban road runoff is scarce. Road runoff of trafficked roads can be heavily polluted and is treated by stormwater quality improvement devices (SQIDs). However, microbes may influence the treatment process of these devices or could lead to stress resistant opportunistic microbial strains. In this study, the microbial community in the influent, effluent and the filter materials used to remove dissolved heavy metals from two different SQIDs were analyzed to determine microbial load, retention, composition, and mobile resistance genes. Although the microbes were replaced by new taxa in the effluent, there was no major retention of microbial genera. Further, the bacterial abundance of the SQIDs effluent was relatively stable over time. The heavy metal content correlated with intl1 and with microbial genera. The filter media itself was enriched with Intl1 gene cassettes, carrying several heavy metal and multidrug resistance genes (e.g. czrA, czcA, silP, mexW and mexI), indicating that this is a hot spot for horizontal gene transfer. Overall, the results shed light on road runoff microbial communities, and pointed to distinct bacterial communities within the SQIDs, which subsequently influence the microbial community and the genes released with the treated water.

A REVIEW ON THE APPLICATION OF GRANULAR FILTER MEDIA AND THE UTILIZATION OF AGRO-INDUSTRIAL WASTES FOR STORMWATER QUALITY IMPROVEMENT

The stormwater management practices have changed from conveyance-oriented to storage-oriented, as part of the Best Management Practices (BMPs). Still, uncontrolled development increases potential pollutants in the stormwater, which conveys into a water body or river. Continuous improvements in the filtration mechanism would complement stormwater management. For the past decades, there is progress in applying granular filter media for stormwater quality improvement. However, the reports were not systematically reviewed. In this paper, the recent five years research that utilizes granular filter media for improving stormwater quality was retrieved and reviewed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was referred to, where Scopus and Web of Sciences, two primary journal databases, were used. Initially, keywords searching strings have resulted in 467 articles, which were further screened. Four themes have been formed: stormwater management, stormwater characteristics, separation mechanisms, and future perspectives. Next, two sub-themes and two sub-sub-themes were further established. Then, 65 articles were included manually to complement the themes developed to explore the potential agro-industrial wastes as sustainable filter media. Therefore, this review has proven that the relatively inexpensive and renewable resources from the agro-industrial wastes can remove pollutants efficiently from the stormwater. Four main criteria affecting filter media performances are also highlighted, including the grain sizes of the media, media bed configuration, hydraulic loading rate, and the suspended solids concentration. Further study on these variables can be beneficial to explore the impact of utilizing agro-based media in stormwater filtration.

Rainwater Management in Urban Areas

Rising levels of impervious surfaces in densely populated cities and climate change-related weather extremes such as heavy rain events or long dry weather periods provide us with new challenges for sustainable stormwater management in urban areas. The Special Issue consists of nine articles and a review and focuses on a range of relevant issues: different aspects and findings of stormwater runoff quantity and quality, including strategies and techniques to mitigate the negative effects of such climate change impacts hydraulically, as well as lab-scale and long-term experience with pollutants from urban runoff and the efficiency of stormwater quality improvement devices (SQIDs) in removing them. Testing procedures and protocols for SQIDs are also considered. One paper analyses the clogging of porous media in the use of stormwater for managed aquifer recharge. The Special Issue demonstrates the importance and timeliness of the topic of sustainable rainwater management, especially with regard to growing cities and the challenges posed by climate change.

Sequential extraction of heavy metals from sorptive filter media and sediments trapped in stormwater quality improvement devices for road runoff

The performance of stormwater quality improvement devices (SQIDs), commonly based on sedimentation and media filtration, is generally examined either at lab scale or in field tests. However, there has so far been only little investigation into the remobilization of heavy metals retained in sediments and sorptive filter media. It is, moreover, unknown whether current lab-scale experiments are able to replicate the conditions of full-scale operation. To assess the potential impact of differences in conditions between lab-scale and field tests on the strength of association of heavy metals, filter media taken from three SQIDs were subjected to analysis by sequential extraction after prestressing both on a lab scale and in field tests. Sediments and filter cake trapped in the SQIDs were additionally analyzed. These displayed significantly higher heavy metal content than filter media that had been prestressed in the field. The zinc in the sediments and filter media displayed particularly high mobility. This study reveals a discrepancy between field and lab-scale conditions that creates differences in the content and strength of association of heavy metals. It is hence possible to show that previous lab-scale experiments potentially overestimated the risk of heavy-metal leaching, due to their predominant occurrence in more mobile fractions.

The Common Approaches of Nitrogen Removal in Bioretention System

Bioretention is considered one of the best management practices (BMPS) for managing stormwater quality and quantity. The bioretention system has proven good performance in removing total suspended solids, oil, and heavy metals. The nitrogen (N) removal efficiency of the bioretention system is insufficient, however, due to the complex forms of nitrogen. Therefore, this paper aims to review recent enhancement approaches to nitrogen (N) removal and to discuss the factors influencing bioretention efficiency. To improve bioretention efficiency, several factors should be considered when designing bioretention systems, including nitrogen concentration, climate factors, and hydrological factors. Further, soil and plant selection should be appropriate for environmental conditions. Three design improvement approaches have been reviewed. The first is the inclusion of a saturated zone (SZ), which has been used widely. The SZ is shown to have the best performance in nitrogen removal. The second approach (which is less popular) is the usage of additives in the form of a mixture with soil media or as a separated layer. This concept is intended to be applied in tropical regions with wet soil conditions and a short dry period. The third approach combines the previous two approaches (enhanced filter media and applying a SZ). This approach is more efficient and has recently attracted more attention. This study suggests that further studies on the third approach should be carried out. Applying amendment material through filter media and integrating it with SZ provides appropriate conditions to complete the nitrogen cycle. This approach is considered a promising method to enhance nitrogen removal. In general, the bioretention system offers a promising tool for improving stormwater quality.

The application of green roof for stormwater quantity and quality improvement

The use of green roof is becoming increasingly worldwide because of its environmental, economic, and aesthetic benefits. The ability to retain storm water and improve the quality of effluent flow are the important characteristics of green roof. It is viewed as a best technology to minimize the negative impact of urbanization. However, the application of green roof in Malaysia is less and literatures regarding these is limited. An attempt has been made to evaluate the performances of green roof in improving the water quantity and quality of stormwater runoff. A lab-scale green roof with five component layers which are vegetation layer using creeping ox-eye and beach morning glory, topsoil substrate layer, non-woven geotextile filter layer, drainage plate layer and liquid waterproofing layer was used. Results indicated that the green roof with creeping ox-eyes shows a better performance in reducing peak flow with as high as 41% percentages of reduction compared to beach morning glory (15%). On the other hand, the green roof with beach morning glory manage to improve the concentration of COD up to 99% improvement while the green roof with creeping ox-eye shows a better performance in improving BOD with 17% reduction.