Field-scale Bioretention Research Articles

Roof runoff pollution control with operating time based on a field-scale assembled bioretention facility: Performance and microbial community dynamics

Bioretention facilities are essential, low-impact development measures to treat roof runoff pollution. To explore the effects of roof runoff pollution control and internal influencing mechanisms of field-scale bioretention facilities, a newly assembled bioretention facility (ABF) comprising volcanic rock and coconut coir was constructed. The results of the 21-month experiment showed that the peak concentrations of total suspended solids (TSS), ammonia nitrogen (NH4+–N), and chemical oxygen demand (COD) of roof runoff were 332.50 mg∙L−1, 3.46 mg∙L−1, and 122.33 mg∙L−1, respectively, indicating that the roof runoff was seriously polluted and needed urgent treatment. The removal rates of TSS, NH4+–N, and COD within the facility were 86.50 ± 7.31 %, 79.40 ± 19.28 %, and 51.84 ± 26.24 %, respectively. However, continuous and high-intensity rainfall decreased pollutant removal performance by weakening the adsorption effect of the media. Continuous pollutant input decreased the abundance of Arthrobacter and Hyphomicrobium within the media, and functional bacteria, such as KD4–96, Roseiflexaceae, Vicinamibacteraceae, and Gaiellales, played dominant roles in NH4+–N and COD removal to ensure the long-term stability of the facility. This study provides theoretical guidance and a practical basis for enhancing the application of ABF in mitigating roof runoff pollution.

Depollution of first flush urban runoff in a field-scale bioretention cell adapted to semi-arid climates

Depollution of first flush urban runoff in a field-scale bioretention cell adapted to semi-arid climates

Applicability assessment of five evapotranspiration models based on lysimeter data from a bioretention system

Evapotranspiration (ET) plays an important role in restoring stormwater retention capacity of bioretention systems and improving microclimate conditions in urban areas. However, there is still a lack of applicable methods to accurately predict ET from bioretention systems. In this study, the applicability of five commonly used models (i.e., ASCE Penman-Monteith, Priestley-Taylor, Penman, Hargreaves, and Blaney-Criddle) in predicting ET from bioretention systems was assessed based on lysimeter measurement data from a field-scale bioretention system located in Beijing. The measured average daily ET from the bioretention system using a lysimeter is 2.24 mm·d−1. ET from the bioretention system is significantly related to solar radiation, vapor pressure deficit, and air temperature (p < 0.001). The ASCE Penman-Monteith, Priestly-Taylor, Penman, and Blaney-Criddle models underestimate average daily ET by 23.31%, 18.50%, 18.93%, and 29.60%, respectively. However, the Hargreaves model overestimates ET by 35.13%. Incorporating various crop coefficients in different plant growth stages can significantly improve the accuracy of these five models. The Penman model is demonstrated to be the most accurate in predicting ET from the bioretention system, followed by the Priestly-Taylor, and ASCE Penman-Monteith models. These three models have relative errors ≤2.68%, RMSE ≤0.66 mm·d−1, R2 ≥0.92, and NSE ≥0.95. The Hargreaves or Blaney-Criddle models could not accurately predict ET from the bioretention system because solar radiation is not considered in these two models. The results provide references for selecting and implementing models to predict ET from bioretention systems.

Control performance of bioretention system on non-point source pollution in typical Chinese rural areas of Southeastern China

Current work focused on analysis and implementation and of bioretention system in typical rural areas in Southeastern China. These areas are vigorously protected by the Chinese government due to their traditional farming and architectural characteristics that symbolize ancient Chinese civilization. Bioretention system with high pollutant removal capacity and strong environment adaptability might be a suitable technical solution for controlling non-point source pollution in ancient Chinese villages. In lab-scale study, the hydraulic characteristics of the media and the impacts of depth of media layer, depth of saturated zone (SZ), vegetation and extra carbon source (ECS) on pollutant removal efficiency of bioretention system against the current situation of NSP in typical Chinese rural areas (TCRA) were investigated. The results revealed that roots were conducive to maintain the hydraulic conductivity and pollutant removal efficiency of the filter media. The increasing depth of media layer and SZ, vegetation, and ECS could improve pollutant controlling performance of bioretention system. A field-scale bioretention system with optimal configuration determined by lab-scale study was implemented on the site. The average removal rates of TSS, COD, TN and TP of the bioretention system in field study were 81.34%, 41.88%, 37.33% and 71.64%, respectively. Bioretention system could combine with nearby farmland in rural areas without disturbing their original texture, furthermore, proper maintenance and replacement of media and vegetation could significantly improve the performance of bioretention system in TCRAs.

Integrating Tank Model and adsorption/desorption characteristics of filter media to simulate outflow water quantity and quality of a bioretention basin: A case study of biochar-based bioretention basin

Reliable approaches for accurately assessing the performance of stormwater treatment systems is essential for their effective design, including filter media selection which can be a significant constituent in stormwater treatment systems. This study presents an innovative modelling approach integrating the Tank Model with the adsorption-desorption characteristics of the filter media. The resulting modelling approach was applied to simulate a field-scale bioretention basin where biochar was used as filter media with over ten years of rainfall records. The resulting outflow and overflow volumes were compared with observed data for calibration. The Stormwater Treatment Tank Model (STTM) was validated using the Leave-One-Out-Cross-Validation (LOOCV) method. The simulation outcomes include water outflow and overflow (quantity) from the bioretention basin as well as outflow water quality represented by three heavy metals (Pb, Cu, and Zn). The modelling approach developed was found to be capable of accurately simulating outflow and overflow volumes, with outlet water quantity being significantly influenced by the total rainfall depth. The modeling results also suggested that a sole treatment system would not be adequate, particularly for large rainfall events (>100 mm) and a treatment train would be more effective. Simulating long-term (over ten years) pollutant removal performance in the bioretention basin indicated that heavy metals outflow event mean concentration (EMCs) values calculated using simulated results of 30% biochar application rate generated the best pollutant removal with consistent values (2.7 μg/L, 3.0 μg/L, 17.2 μg/L for Pb, Cu, and Zn, respectively). These results confirm that the modelling approach is reliable for assessing long-term treatment performance, as well as a robust tool able to contribute to more effective treatment system design, particularly filter media selection and evaluation.

Behaviour of soluble reactive phosphorus within field-scale bioretention systems

Soluble reactive phosphorus (SRP) in urban runoff can contribute to eutrophication of downstream water bodies. Bioretention systems, a popular low impact development (LID) practice, have the potential to reduce SRP loads in urban runoff. In this study, six field-scale bioretention systems located in southern Ontario, Canada, with different soil media compositions were monitored to evaluate their performance with respect to SRP retention and to identify the geochemical processes influencing SRP behaviour within the systems. The physical and chemical characteristics of the soil media were analysed to compare the systems as well as to assess whether the installed soil media compositions met the LID bioretention design guidelines. To examine how SRP evolves as stormwater infiltrates through the different media, porewater was collected from multiple depths within the bioretention systems. The geochemical processes controlling SRP retention-release were identified by chemical analysis of the porewater and selective solid phase extractions. The geochemical processes governing SRP behaviour differed between the bioretention systems with processes validated via one-dimensional reactive transport simulations conducted in PHREEQC. Results indicate: 1) Soil media characteristics are highly variable between systems despite the systems having the same overall engineering design specifications; 2) Porewater SRP does not evolve uniformly with depth indicating the importance of overall system design including redox conditions, infiltration rate, and vertical layering of different materials (e.g., surface cover layer and bioretention media); 3) SRP retention-release processes often occur at shallow depth (<0.1 m) and more attention is needed to assess the impact of different surface cover layers used in field installations; 4) Hydraulic conductivity controls the residence time of water in the systems which in turn influences SRP retention-release; 5) SRP adsorption onto Al- and/or Fe-oxides is the main retention mechanism in systems with high hydraulic conductivity while Ca phosphate mineral precipitation may be important in systems with low hydraulic conductivity. The study findings provide insights needed to improve the field performance of bioretention systems in retaining SRP including the testing and application of soil media amendments for enhancing SRP retention.

Seasonal performance of field bioretention systems in retaining phosphorus in a cold climate: Influence of prolonged road salt application.

Bioretention systems are popular low impact development stormwater management features designed to remove pollutants, including phosphorus (P), from urban stormwater runoff. While the performance of bioretention systems in retaining P has been well studied, seasonal variability of P retention in field-scale systems installed in cold climates, including the influence of high road de-icing salt (sodium chloride) inputs, remains unclear. Two large field-scale bioretention systems installed in London, Ontario, Canada were monitored over their initial operational period to evaluate the seasonal trends in the retention of different forms of P in bioretention systems and the impact of high salt loading. Over the 12-month monitoring period, a net retention of total P and dissolved organic P, and a net release of soluble reactive P and total dissolved P mass were observed. Reduced hydrological performance and increased effluent P concentrations resulted in high P release from the bioretention systems in early to mid-spring (March and April), with most release occurring during a few individual large precipitation events. Laboratory-scale column experiments were performed using the engineered soil media installed in the field-scale bioretention systems to isolate the effect of high salt loading on P release. Column experiments combined with field data indicate that prolonged high salt loads through winter and spring may have contributed to elevated spring P release, mostly in the form of soluble reactive P, from the field-scale bioretention systems. Findings from this study are needed to better understand the performance of bioretention systems with respect to P retention as required to improve urban stormwater management in cold climates. Results have implications for further investigations of the impact of road salt on P mobility in bioretention systems and more broadly in roadside soils and groundwater systems.

Waste-derived compost and biochar amendments for stormwater treatment in bioretention column: Co-transport of metals and colloids

Bioretention systems, as one of the most practical management operations for low impact development of water recovery, utilize different soil amendments to remove contaminants from stormwater. For the sake of urban sustainability, the utilization of amendments derived from waste materials has a potential to reduce waste disposal at landfill while improving the quality of stormwater discharge. This study investigated the efficiency of food waste compost and wood waste biochar for metal removal from synthetic stormwater runoff under intermittent flow and co-presence of colloids. Throughout intermittent infiltration of 84 pore volumes of stormwater, columns amended with compost and biochar removed more than 50–70% of influent metals, whereas iron-oxide coated sand was much less effective. Only a small portion of metals adsorbed on the compost (< 0.74%) was reactivated during the drainage of urban pipelines that do not flow frequently, owing to abundant oxygen-containing functional groups in compost. In comparison, co-existing kaolinite enhanced metal removal by biochar owing to the abundance of active sites, whereas co-existing humic acid facilitated mobilization via metal-humate complexation. The results suggest that both waste-derived compost and biochar show promising potential for stormwater harvesting, while biochar is expected to be more recalcitrant and desirable in field-scale bioretention systems.

Effective nitrogen removal during different periods of a field-scale bioretention system.

Bioretention systems are designed to manage stormwater, but they are always subject to substantial nitrate leaching. In previous laboratory-scale experiments, nitrate removal was enhanced using wood chips as a medium. However, the ability of field-scale systems to transform and remove nitrogen species is not well understood. Here, we report a wood-chip bioretention system that accepts the natural runoff from an elevated highway. The transformation of different nitrogen species indicates that the field-scale system with wood chips also inhibits nitrogen leaching. Nitrate removal was mainly found during the wet period, and was affected by the hydraulic loading rate of the system. Overall, this study showed that the field performance of the wood-chip bioretention system effectively removes nitrogen. In addition, the main period associated with the nitrogen removal process was identified.

Evaluation of pollutant removal efficiency of a bioretention basin and implications for stormwater management in tropical cities

Field-scale bioretention basin performance in treating a full suite of nutrients is critically evaluated in the data-scarce tropics.

Modeling Field-Scale Bioretention Cells with Heterogeneous Infiltration Media

To address increasing stormwater management concerns in metropolitan and suburban areas, bioretention systems are a mitigation technology that helps address both water quantity and quality. However, it is critical for stormwater managers and engineers to model the hydraulic performance of these systems before investing in the infrastructure. This means an appropriate model must be selected to efficiently reflect important aspects of the given site and design. This work investigated the ability of a one-dimensional model to simulate water movement through a heterogeneous bioretention cell. For model validation, two full-size bioretention cells in Grove, Oklahoma, were flooded a total of three times, and parameters related to overflow, drainage and relative change in soil moisture were measured. Observed values were compared to predictions using an uncalibrated model previously developed and run with area-weighted soil parameters (“original model”). In addition, observations were compared to an uncalibrated “revised model,” which allowed modeling of distinct infiltration media. The revised model allowed for two separate soil types in the horizontal plane and simulated maximum subsurface drainage flow rate (23.6% to 33.7% from observed), volume (7.9% to 38.9% from observed), and timing (14.7% to 92.5% from observed) better than the original model, but the original model generally simulated overflow volume (12.2% to 77.1% from observed) and peak overflow rate (3.6% to 9.6% from observed) more closely. It was concluded that the revised model was more appropriate for modeling heterogeneous systems when concerns exist about timing of hydrographs and all underdrain parameters.

Design and hydraulic characteristics of a field-scale bi-phasic bioretention rain garden system for storm water management

A field-scale bioretention rain garden system was constructed using a novel bi-phasic (i.e. sequence of anaerobic to aerobic) concept for improving retention and removal of storm water runoff pollutants. Hydraulic tests with bromide tracer and simulated runoff pollutants (nitrate-N, phosphate-P, Cu, Pb, and Zn) were performed in the system under a simulated continuous rainfall. The objectives of the tests were (1) to determine hydraulic characteristics of the system, and (2) to evaluate the movement of runoff pollutants through the system. For the 180 mm/24 h rainfall, the bi-phasic bioretention system effectively reduced both peak flow (approximately 70%) and runoff volume (approximately 42%). The breakthrough curves (BTCs) of bromide tracer suggest that the transport pattern of the system is similar to dispersed plug flow under this large runoff event. The BTCs of bromide showed mean 10% and 90% breakthrough times of 5.7 h and 12.5 h, respectively. Under the continuous rainfall, a significantly different transport pattern was found between each runoff pollutant. Nitrate-N was easily transported through the system with potential leaching risk from the initial soil medium, whereas phosphate-P and metals were significantly retained indicating sorption-mediated transport. These findings support the importance of hydraulics, in combination with the soil medium, when creating bioretention systems for bioremediation that are effective for various rainfall sizes and intervals.