Difference between revisions of "Filter Media Additives for Phosphorus Removal"
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Determining when additive enhanced filter media needs replacing or maintenance represents a new challenge for stormwater asset managers, as there are no suitable visual indicators. Erickson et al. (2018) suggest effluent sampling and laboratory testing to identify when enhanced filter media pollutant retention is waning, or periodic sampling and batch (laboratory) testing of filter media to directly measure its capacity to retain the targeted pollutants<ref>Erickson, A.J., Taguchi, V.J., Gulliver, J.S. 2018. The Challenge of Maintaining Stormwater Control Measures: A Synthesis of Recent Research and Practitioner Experience. Sustainability. 2018, 10, 3666. https://www.mdpi.com/2071-1050/10/10/3666 </ref>. Periodic replacement of filter media at inlet locations should be considered as an operation and maintenance best practice to maintain treatment performance. | Determining when additive enhanced filter media needs replacing or maintenance represents a new challenge for stormwater asset managers, as there are no suitable visual indicators. Erickson et al. (2018) suggest effluent sampling and laboratory testing to identify when enhanced filter media pollutant retention is waning, or periodic sampling and batch (laboratory) testing of filter media to directly measure its capacity to retain the targeted pollutants<ref>Erickson, A.J., Taguchi, V.J., Gulliver, J.S. 2018. The Challenge of Maintaining Stormwater Control Measures: A Synthesis of Recent Research and Practitioner Experience. Sustainability. 2018, 10, 3666. https://www.mdpi.com/2071-1050/10/10/3666 </ref>. Periodic replacement of filter media at inlet locations should be considered as an operation and maintenance best practice to maintain treatment performance. | ||
| + | ===Disclaimer=== | ||
{{:Disclaimer}} | {{:Disclaimer}} | ||
Revision as of 14:15, 18 August 2025
Overview[edit]
Design innovations to improve water quality treatment performance of filter media mixtures involve the incorporation of additives to enhance retention of reactive or dissolved pollutants, such as phosphorus. A number of granular amendments have been demonstrated to improve nutrient removal from discharge water in BMPs such as bioretention systems, stormwater planters, absorbent landscapes, sand filters or green roofs.
There are two primary processes involved, chemical precipitation and adsorption. Both mechanisms are ultimately finite, but have been shown in some cases to make significant improvements on the discharged water quality over several years. For instance, a two year STEP research study that compared standard bioretention media, to the same media amended with Sorbtive™ in one plot and iron enriched sand (aka red sand) in another showed statistically significant improvements in effluent phosphorus concentrations from the two media amended plots (STEP, 2019)[1].
Determining when additive enhanced filter media needs replacing or maintenance represents a new challenge for stormwater asset managers, as there are no suitable visual indicators. Erickson et al. (2018) suggest effluent sampling and laboratory testing to identify when enhanced filter media pollutant retention is waning, or periodic sampling and batch (laboratory) testing of filter media to directly measure its capacity to retain the targeted pollutants[2]. Periodic replacement of filter media at inlet locations should be considered as an operation and maintenance best practice to maintain treatment performance.
Disclaimer[edit]
In our effort to make this guide as functional as possible, we have decided to include proprietary systems and links to manufacturers websites.
Inclusion of such links does not constitute endorsement by the Sustainable Technologies Evaluation Program.
Lists are ordered alphabetically; link updates are welcomed using the form below.
| Material | Benefits | Potential concerns |
|---|---|---|
| Biochar | Renewable Enhances soil aggregation, water holding capacity and organic carbon content |
Currently expensive Energy intensive to produce Some sources say ineffective for phosphorus removal |
| Bold & GoldTM | Documented total phosphorus removal of up to 71% (Hood et al., 2013)[3] | Proprietary P contributions during backwater conditions (FDOT, 2014)[4]. |
| Iron filings or Zero valent iron (ZVI) | Proven phosphorus retention Retained phosphorus is stable |
May harm plants (Logsdon & Sauer, 2016) [5] Removal efficiency declines with increased concentration of incoming phosphorus |
| Red sand or Iron-enriched sand | Proven phosphorus removal Also removes TSS |
Poor orthophosphate removal in hypoxic or anoxic conditions |
| Smart SpongeTM | Removes phosphorus, as well as TSS, fecal coliform bacteria and heavy metals Non-leaching |
1-3 year lifespan, after which the product is removed as solid waste Proprietary |
| Sorbtive MediaTM | High phosphorus removal efficiency | Proprietary pH control needed (Zhang, 2023)[6] |
| Water treatment residuals | Waste product reuse | Quality control (capabilities depend on source, treatment methods, storage time) |
Biochar[edit]
What Is It?[edit]
Biochar is a carbon-rich material produced by pyrolysis of organic feedstocks such as municipal, agricultural, and forestry wastes. It has a high surface area, which enhances soil aggregation, water holding capacity, and organic carbon content. However, biochar properties and effectiveness for pollutant sorption depends on feedstock and pyrolysis conditions (Iqbal et al., 2015). [7]
How is it being used?[edit]
- Biochar additions to green roof substrate were tested at the University of Toronto. Biochar-amended sedum green roofs presented the best integrated water quality, including reduced discharge concentrations of dissolved P (Liao et al., 2024)[8].
- Ongoing biochar research at the British Columbia Institute of Technology is testing the response of native plants to various soil/biochar mixes to be used in rain gardens and the comparison of biochar with different physico-chemical characteristics in chemical contaminants removal efficacy (BCIT, 2025) [9].
- A bioretention system in China used biochar layered with or mixed into lateritic red soil, with some success in contaminant removal. The mixed biochar–soil design achieved the highest water retention, and both biochar-amended systems removed more contaminants (TN, NH₃-N, NO₃⁻, TP, PO₄³⁻, and Cu) than systems without biochar (Premarantha et al., 2023) [10].
- In Delaware, two roadside filter strips amended with biochar reduced peak flow and runoff volume, but showed no notable change in pollutant concentrations (Center for Watershed Protection, Inc., 2025) [11].
- In field experiments in Europe, biochar reduced nutrient leaching in green roofs, but did not reduce nutrient concentrations in effluent (Kuoppamäki et al., 2016) [12].
Benefits[edit]
One study states that the mixing of biochar with compost did not decrease the phosphorus leaching from the mixture (Iqbal et al., 2015). [7] Based on this study, it would seem that biochar is ineffective for phosphorus removal. An Australian study found that phosphorus removal efficiency was inversely related to the biochar content of sand media when used to treat secondary sewage and septage in constructed wetland mesocosms (Rozario et al., 2016)[13]. Another study, located in Portland, found that biochar could reduce metal concentrations in stormwater when used as an amendment to bioretention systems but has a limited impact on nutrients [14].
However, some other papers indicate that biochar mixed with sand was able to retain some trace organic contaminants (TOrCs) (Ulrich et al., 2015), [15] and that after six months of operation, biochar-amended biofilters improved removal of total dissolved phosphorus and other TOrCs by greater than 60% (Ulrich et al., 2017a). [16] Amendment of LID systems with biochar has shown promise for improved removal of heavy metals, bacteria, nutrients, and TOrCs (Ulrich et al., 2017b). [17]
Bold & Gold[edit]
What is it?[edit]
Bold & Gold is a biosorption activated media (BAM) for pollution control developed by the Stormwater Management Academy at the University of Central Florida. It can be used to achieve nitrogen and phosphorus reduction in stormwater, wastewater and agricultural applications such as retention basins, swales and rain gardens, urban gardens and soil cells, permeable pavements, green roofs, filter strips and more. Bold & Gold is composed of a patented blend of mineral materials, sand, and clay.
How is it being used?[edit]
- Bold & Gold was used to remove total phosphorus in an urban on-line up-flow filter and an off-line filter in Florida (FDOT, 2014)[19].
- It was also used in Florida in residential swales covered with native soil and sod to remove nitrogen and phosphorus from stormwater (FDOT, 2023)[20].
- No projects that used Bold & Gold were found in Ontario.
Detailed drawings and product specifications are available here.
Benefits[edit]
The results of a study by Hood, Chopra, and Wanielista (2013) provided promising results for the use of Bold & Gold for phosphorus removal. In field scale testing, Bold & Gold had a 71% removal efficiency of total phosphorus. This was compared to sandy soil which had many negative values, indicating significant leaching of total phosphorus from the sod. The average Soluble Reactive Phosphorus (phosphorus that is readily available to plants and algae) removal efficiency was 95%. Overall, the Bold & Gold system performed much better when compared to a sandy soil bio-filtration system [21].
Iron filings (ZVI)[edit]
What is it?[edit]
Iron filings or zero-valent iron (ZVI) is the elemental form of iron with a zero charge carried by each atom – a result of the outer valence level being filled. ZVI is able to remove dissolved phosphorus (phosphate) from solution through precipitation (Rossetti, 2017)[22]. Zero-valent iron nanoparticles (nZVI) are also used for phosphorus removal.
How is it being used?[edit]
- A field study in Maplewood, Minnesota used an iron-enhanced (5% iron filings) ditch check sand filter for installation in swales to provide treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff from highways (Ahmed at el., 2014) [23].
- In Ajax, Ontario, iron filings were tested as an additive in bioretention areas and compared against two alternatives: a bioretention area with 5% sorbtive media, and a typical engineered media bed consisting of a shredded hardwood mulch layer over a sand–soil–organic mixture. Phosphorus concentrations were lowest in the sorbtive media mix, followed by the iron filing mix, while the typical media bed had the poorest removal performance (Aquafor Beech, 2018)[24].
Benefits[edit]
A study was done that compared the phosphorus reduction capabilities of ZVI, biochar, biochar-supported ZVI (ZVI/BC), and biochar-supported nZVI (nZVI/BC) (Rossetti, 2017)[22]. It was found that nZVI/BC had the highest phosphorus reduction. Using biochar-supported ZVI or nZVI improves the dispersion and stability of the iron filings. Biochar is fine-grained and highly porous, providing a large surface area to support nZVI. Another paper reports that ZVI can remove up to 98% of influent phosphorus at low input concentrations, and at high concentrations is shown to remove up to 36% of incoming phosphorus. The phosphorus retained in the soil is mostly iron-bound, which will not be easily leached out of the system because it is very stable (Lechner, 2016)[25].
Red sand[edit]
What is it?[edit]
Red sand, also known as a "Minnesota filter", is iron enhanced sand designed to capture soluble phosphorus that generally passes through a typical stormwater management facility. Iron has an affinity for dissolved phosphorus, which will serve to bind and therefore remove a portion of the dissolved phosphorus from the stormwater (LSRCA, 2013)[27]. The sand also filters the stormwater by removing a portion of the suspended solids and total phosphorus that may be attached to those particles (LSRCA, 2013)[27].
How is it being used?[edit]
- The first retrofit in Ontario to incorporate a red sand filter system was the George Richardson stormwater management pond in Newmarket(LSRCA, 2013)[27]. Red sand was installed as the last part of a treatment train to function as a final polishing unit. The underground system was first lined with a bentonite clay liner to minimize groundwater exchange, with various layers of clear stone and red sand sandwiched between nonwoven geotextiles. The water is distributed via a system of perforated pipes embedded in the top layer of the underground system just above the red sand filter media, with collector pipes located near the bottom. The system is estimated to have a reduction in phosphorus of 23 kg/year (CVC, 2013)[28].
- Another Ontario project was completed by the Upper Thames River Conservation Authority and Luckhart Transportation Limited, in which they retrofit an innovative wetland treatment system to test a red sand filter. This was the first of its kind for an agricultural application. In this project, a clear round stone was added to improve percolation and phosphorus retention (Upper Thames River Conservation Authority, 2014)[29].
- In a two year STEP research study that compared standard bioretention media to red sand and Sorbtive™ amended media, the red sand plot was shown to have significantly lower total and dissolved phosphorus effluent concentrations. However the phosphorus reductions occurred only in year 2, after fine particulates in the red sand media had been washed out of the system (STEP, 2019)[30].
Benefits[edit]
Early data from the George Richardson site indicate a reduction in total suspended solids and phosphorus after going through the system (CVC, 2013)[28]. "Average TP concentrations into the filter were 0.12 mg/L with a maximum of 0.54 mg/L as compared to an average outlet concentration of 0.052 mg/L with a maximum of 0.13 mg/L. Average soluble phosphorus (orthophosphate) concentrations into the filter were 0.01mg/L with a maximum of 0.031 mg/L as compared with an average outlet concentration of 0.007 mg/L with a maximum of 0.044 mg/L" (LSRCA, 2013)[27]. Poor orthophosphate removal was observed during hypoxic or anoxic conditions because the iron/phosphorus bond that facilitates the removal of orthophosphate can be broken under low oxygen conditions (LSRCA, 2013)[27].
Smart Sponge[edit]
What is it?[edit]
Smart Sponge is a polymer technology produced by AbTech Industries (AbTech Industries, 2017a).[31] Smart Sponge “uses renewable resource based metal nanocomposites extruded into an adsorptive sponge media. The media will bind with phosphorus and heavy metals resulting in removal rates as high as 98%” (AbTech Industries, 2017b)[32]
How is it being used?[edit]
- Three different types of sponges were installed in catch basins in Kearney Point NJ to reduce contaminants in stormwater runoff to the Hackensack River—Smart Sponge for hydrocarbon removal; Smart Sponge HM for heavy metal removal; and Smart Sponge BC (BioChar/EcoChar), which removes both heavy metals and hydrocarbons (Stormwater Solutions, 2019)[33].
- No projects have been found in Ontario to date.
Benefits[edit]
The Department of Civil and Environmental Engineering at Louisiana State University in partnership with the Louisiana Transportation Research Center did an investigation of the contaminant removal efficiency of different materials to reduce the discharge of various pollutants from linear transportation systems. Stormwater treatment experiments were conducted using three laboratory columns filled with different combinations of filter medium layers, and the optimum filter medium combination was found to be a mixture of Smart Sponge and Hydro CX2 (a type of fibre mulch) in the top layer, with other layers of zerolite, sand, sawdust, and gravel. Results of the laboratory experiments indicate that this layer combination is able to remove 90% of total phosphorus (as well as a majority of the total suspended solids, fecal coliform bacteria and heavy metals) (Deng et al., 2017)[34]. The Environmental Protection Agency’s Toxicity Characteristic Leaching Procedure tests have shown that Smart Sponge is a non-leaching product. This means that after its lifespan (1-3 years), it can be removed as solid waste and disposed of in waste-to-energy facilities, cement kilns, or landfills (AbTech Industries, 2017b). [32]
Sorbtive media[edit]
What is it?[edit]
Sorbtive MediaTM is an oxide-based, high surface area reactive engineered media that absorbs and retains large amounts of dissolved phosphorus. It does not desorb (leach) pollutants and has a low total phosphorus effluent concentration (< 0.1 mg/L). Sorbtive MediaTM controls phosphorus by two mechanisms:
- Physical filtration is the removal of particulate-bound phosphorus and sediment, and
- Sorption is the physio-chemical removal of dissolved phosphorus (the biologically available portion)(Imbrium Systems, 2017)[35].
How is it being used?[edit]
Imbrium's Sorbtive MediaTM webpage provides links to technical specifications and design help, along with highlights of multiple projects where the product has been used for phosphorus removal (Imbrium Systems, 2017)[36].
- At the Sturgeon Meadows Stormwater Management Facility in Leamington, Ontario, Sorbtive MediaTM was applied as a retrofit component to enhance pollutant removal withing an existing dry pond as part of a treatment train. A 30 cm layer was applied within retrofitted trenches in combination with washed stone and rip rap rock to manage the expected treatment flow.
- The Rumble Pond Retrofit project in Richmond Hill, Ontario used Sorbtive MediaTM in combination with permeable interlocking pavers to enhance overall capacity of the pervious pavers.
- A partnership between Credit Valley Conservation and the University of Guelph completed a project at the IMAX Corporation headquarters in which Sorbtive MediaTM was used downstream of a bioretention cell to provide tertiary nutrient treatment. The bioretention cell with the Sorbtive Media Vault post-treatment had significantly lower TP and SRP compared to the simple bioretention cell and bioretention cell with Jellyfish prefilter. However, the highest maintenance expense for this project was associated with the Jellyfish Filters and the Sorbtive Media Vault (CVC, 2022)[37].
- A project at Mayville Park in Upstate New York used six retrofit filtration cells surrounding draining inlets near a community centre, which previously had no stormwater treatment on-site (Imbrium Systems, 2017)[35]. In addition to these projects included on their website, Sorbtive MediaTM was installed at the Colony Trail retrofit in East Gwillimbury. The Imbrium Sorbtive MediaTM chamber removed an average of 66 % of dissolved phosphate from the site (LSRCA, 2013)[38].
Benefits[edit]
A pilot study was undertaken by researchers at Fleming College in Ontario, Canada to assess the phosphorus removal performance of bioretention soil mix amended with Sorbtive Media. Five bioretention cells were constructed and filled with a soil mix comprised of sand, peat moss, and various percentages of Sorbtive MediaTM. Batches of artificial stormwater containing differing concentrations of phosphorus were used to simulate storm events on the bioretention cells. Through analysis of the influent and effluent concentrations, it was determined that the amended bioretention cells demonstrated substantial improvement in phosphorus removal. Each of the amended cells maintained removal efficiency of up to 99 % and at least 84 % for the duration of the study, even when blended into the soil mix at only 3 - 5 % volume basis (Balch et al., 2013)[39].
Water treatment residuals[edit]
What is it?[edit]
Water treatment residuals (WTR) are primarily sediment, metal (alumunium, iron, or calcium) oxide/hydroxides, activated carbon, and lime removed from raw water during the water purification process. The effectiveness of WTR in reducing soluble phosphorus depends on several factors, including source water characteristics, water treatment methods, and length of residual storage time prior to land application. Different water treatment facilities create different physical and chemical compositions and phosphorus sorption capability of WTR (Agyin-Birikorang eta l., 2016)[40].
How is it being used?[edit]
- A study conducted in New Jersey found that phosphorus was effectively adsorbed by aluminum-based WTR-coated wood mulches in tests using synthetic urban stormwater (Soleimanifar et al., 2016)[41].
- A field study, also conducted in New Jersey, used aluminum-based WTR granules in parking lot catch basins to reduce dissolved phosphorus, total phosphorus, and metal concentrations in stormwater runoff (Na Nagara et al., 2022)[42].
- A lab study was conducted using three bioretention media (with and without WTR amendment) from Dorchester, Dundas, and Sarnia (Ontario) systems exposed to artificial stormwater with periodically high salt concentrations. All WTR-amended bioretention media showed net phosphorus retention, whereas non-amended media released phosphorus (Pinto, 2023)[43].
Benefits[edit]
Past research done on the efficiency of the use of WTR for phosphorus reduction is promising. Laboratory studies have shown that WTRs adsorb large amounts of phosphorus and increase the phosphorus-sorbing capacity of soils. This decreases phosphorus losses in runoff and leaching. Surface application of WTRs showed an 88% reduction in runoff and leachate dissolved phosphorous (Agyin-Birikorang et al., 2016)[40]. Agyin-Birikorang et. al. (2016) also state that phosphorous sorption by aluminum-based WTRs is practically irreversible[40]. Results from another study state that WTR can be used for phosphorous removal in engineered wetlands and it carries the benefits of reuse of a by-product that promotes sustainability (Babatunde et al., 2015)[44]. It is estimated that the phosphorous adsorptive capacity of amended bioretention filter media, which was mixed with 4% of WTR, was 4 times as high as the traditional media under the same conditions (Wang et al., 2014)[45].
References
- ↑ STEP. 2019. Improving nutrient retention in bioretention. Technical Brief. Accessed: https://sustainabletechnologies.ca/app/uploads/2019/06/improving-nutrient-retention-in-bioretention-tech-brief.pdf
- ↑ Erickson, A.J., Taguchi, V.J., Gulliver, J.S. 2018. The Challenge of Maintaining Stormwater Control Measures: A Synthesis of Recent Research and Practitioner Experience. Sustainability. 2018, 10, 3666. https://www.mdpi.com/2071-1050/10/10/3666
- ↑ Hood A, Chopra M, Wanielista M. 2013. Assessment of Biosorption Activated Media Under Roadside Swales for the Removal of Phosphorus from Stormwater. Water. 5(1):53-66. doi:10.3390/w5010053.
- ↑ FDOT. 2014. Demonstration Bio Media for Ultra-urban Stormwater Treatment. https://www.fergusonwaterworks.com/wp-content/uploads/2022/11/Demonstration-Bio-Media-For-Ultra-Urban-Stormwater-Treatment-1.pdf. Accessed August 2025.
- ↑ Logsdon SD, Sauer PA. 2016. Iron Filings Cement Engineered Soil Mix. Agron J. 108(4):1753. doi:10.2134/agronj2015.0427.
- ↑ Zhang, Y. 2023. Mitigation of nutrient leaching from bioretention systems using amendments. (Master's thesis, University of Calgary) https://ucalgary.scholaris.ca/server/api/core/bitstreams/173ab8e3-6c26-4d92-987d-91d998e0ef32/content.
- ↑ 7.0 7.1 Iqbal H, Garcia-Perez M, Flury M. 2015. Effect of biochar on leaching of organic carbon, nitrogen, and phosphorus from compost in bioretention systems. Science of the Total Environment. 521-522: 37-45. doi: 10.1016/j.scitotenv.2015.03.060
- ↑ Liao, W., Sidhu, V., Sifton, M., Margolis, L., Drake, J., Thomas, S. 2024. Biochar and vegetation effects on discharge water quality from organic-substrate green roofs,
- ↑ BCIT. 2025. Biochar Amended Soil Matrix for Green Stormwater Infrastructure. https://commons.bcit.ca/nbs/rain-gardens-bioretention-cells/
- ↑ Premarathna, K. S. D., Biswas, J. K., Kumar, M., Varjani, S., Mickan, B., Show, P. L., Lau, S. Y., Novo, L. A. B., & Vithanage, M. 2023. Biofilters and bioretention systems: the role of biochar in the blue-green city concept for stormwater management. Environmental Science: Water Research and Technology, 9(12), 3103-3119. Advance online publication. https://doi.org/10.1039/d3ew00054k. https://pure.sruc.ac.uk/ws/portalfiles/portal/74040133/D3EW00054K_authors_accepted_version.pdf
- ↑ Center for Watershed Protection, Inc. 2025. Biochar for bioretention systems: A Review of Biochar use in Bioretentions, Biofilters, and Bioretention Soil Media. https://www.chesapeakebay.net/files/documents/Appendix-A-Biochar-for-Bioretention-Systems_Literature-Review-031725.pdf
- ↑ Kuoppamäki, K., Hagner, M., Lehvävirta, S. & Setälä, H. 2016. Biochar amendment in the green roof substrate affects runoff quality and quantity. Ecological Engineering, Vol. 88, pp. 1–9.
- ↑ P. de Rozari, M. Greenway, A. El Hanandeh. 2016. Phosphorus removal from secondary sewage and septage using sand media amended with biochar in constructed wetland mesocosms. https://doi.org/10.1016/j.scitotenv.2016.06.096.
- ↑ Struzak, M., Poor, C., Wolfand, J., Radke, A. 2024. Evaluation of Biochar as an Amendment for the Removal of Metals, Nutrients, and Microplastics in Bioretention Systems. https://ascelibrary.org/doi/abs/10.1061/JOEEDU.EEENG-7487
- ↑ Ulrich B, Im E, Werner D, Higgins C. 2015. Biochar and Activated Carbon for Enhanced Trace Organic Contaminant Retention in Stormwater Infiltration Systems. Environ. Sci. Technol. 49:6222-6230. doi: 10.1021/acs.est.5b00376.
- ↑ Ulrich B, Loehnert M, Higgins C. 2017a. Improved contaminant removal in vegetated stormwater biofilters amended with biochar. Environ. Sci.: Water Res. Technol. 3:726-734. doi: 10.1039/C7EW00070G
- ↑ Ulrich B, Vignola M, Edgehouse K, Werner D, Higgins C. 2017b. Organic Carbon Amendments for Enhanced Biological Attenuation of Trace Organic Contaminants in Biochar-Amended Stormwater Biofilters. Environ. Sci. Technol. 51:9184-9193. doi: 10.1021/acs.est.7b01164.
- ↑ Ferguson Waterworks. 2025. Bold & Gold® Filtration Media. https://www.fergusonwaterworks.com/product/bold-gold-filtration-media//
- ↑ FDOT. 2014. Demonstration Bio Media for Ultra-urban Stormwater Treatment. https://www.fergusonwaterworks.com/wp-content/uploads/2022/11/Demonstration-Bio-Media-For-Ultra-Urban-Stormwater-Treatment-1.pdf. Accessed August 2025.
- ↑ FDOT. 2023. Cape Coral North 2 Utilities Expansion Project (UEP). https://www.fergusonwaterworks.com/case-study/cape-coral-north-2-utilities-expansion-project/
- ↑ Hood A, Chopra M, Wanielista M. 2013. Assessment of Biosorption Activated Media under Roadside Swales for the Removal of Phosphorus from Stormwater. Water. 5:53-66. doi: 10.3390/w5010053.
- ↑ 22.0 22.1 Rossetti M. 2017. Evaluation of phosphorous removals by biochar supported nano-scale zero-valent iron. Chemical Engineering Undergraduate Honors Thesis.
- ↑ Ahmed, F., Natarajan, P., Gulliver, J., Weiss, P., Nieber, J. 2014. Assessing and Improving Pollution Prevention by Swales. https://www.lrrb.org/pdf/201430.pdf
- ↑ Aquafor Beech Ltd. 2018. Monitoring Report (2015–2017): Rain Garden Performance Monitoring Program: Lake Driveway. https://www.ajax.ca/en/get-involved/resources/Stormwater/Rain-Garden-Performance-Monitoring-Program-Lake-Driveway.pdf
- ↑ 25.0 25.1 Lechner L. 2016. Phosphorus Removal From Stormwater Using Zero-Valent Iron. Applied Science Masters Thesis.
- ↑ Minnesota Stormwater Manual. https://stormwater.pca.state.mn.us/index.php/Design_criteria_for_iron_enhanced_sand_filter
- ↑ 27.0 27.1 27.2 27.3 27.4 Lake Simcoe Region Conservation Authority. 2013. Showcasing Water Innovation: Stormwater Performance Monitoring Report. https://lsrca.on.ca/wp-content/uploads/2023/07/Stormwater-Performance-Monitoring-opt.pdf. Accessed August 2025.
- ↑ 28.0 28.1 Credit Valley Conservation. 2013. George Richardson Stormwater Management Pond Retrofit. http://www.creditvalleyca.ca/wp-content/uploads/2013/08/CVC-Case-Study-George-Richardson_Aug_2013.pdf. Accessed September 8, 2017.
- ↑ Upper Thames River Conservation Authority. Red Sand helps Protect Water Quality. 2014. http://thamesriver.on.ca/2014/11/11/red-sand-helps-protect-water-quality-november-11-2014/. Accessed September 8, 2017.
- ↑ STEP. 2019. Improving nutrient retention in bioretention. Technical Brief. Accessed: https://sustainabletechnologies.ca/app/uploads/2019/06/improving-nutrient-retention-in-bioretention-tech-brief.pdf
- ↑ AbTech Industries. 2017a. Smart Sponge. https://www.abtechindustries.com/water-filtration-media
- ↑ 32.0 32.1 Abtech Industries. 2017b. Smart Sponge Heavy Metals (HM). https://www.abtechindustries.com/smart-sponge-hm. Accessed November 2, 2017.
- ↑ Stormwater Solutions. 2019. Filtration Your Way: Kearny Point Industrial Park. https://www.stormwater.com/stormwater-bmps/article/21080689/filtration-your-way
- ↑ Deng, Z. First Flush Reactor for Stormwater Treatment for Elevated Linear Transportation Projects. Louisiana State University and Louisiana Transportation Research Center. 2009. Accessed November 2, 2017: http://www.ltrc.lsu.edu/pdf/2010/08_3tire.pdf
- ↑ 35.0 35.1 Imbrium Stormwater Treatment Solutions. Sorbtive Media. http://www.imbriumsystems.com/stormwater-treatment-solutions/sorbtive-media. Accessed October 6, 2017
- ↑ Imbrium Systems. 2017. Sorptive Media. https://www.imbriumsystems.com/stormwater-treatment-solutions/sorbtive-media
- ↑ Credit Valley Conservation. 2022. IMAX Low Impact Development Feature Performance Assessment. https://sustainabletechnologies.ca/app/uploads/2022/03/rpt_IMAXreport_f_20220222.pdf
- ↑ Lake Simcoe Region Conservation Authority (LSRCA). Showcasing Water Innovation: Stormwater Performance Monitoring Report. 2013. http://www.lsrca.on.ca/Shared%20Documents/reports/swi_monitoring_2013.pdf. Accessed October 6, 2017.
- ↑ Balch G. Broadbent H, Wootton B, Collins S. Phosphorus Removal Performance of Bioretention Soil Mix Amended with Imbrium Systems Sorbtive Media. 2013. Centre for Alternative Wastewater Treatment, in association with Fleming College. http://www.imbriumsystems.com/Portals/0/documents/sm/technical_docs/Fleming%20College%20CAWT%20Report%20on%20Sorbtive%20Media%20Performance.pdf
- ↑ 40.0 40.1 40.2 Agyin-Birikorang S, O’Connor G, Obreza T. 2016. Drinking Water Treatment Residuals to Control Phosphorus in Soils. UF/IFAS Extension.
- ↑ Soleimanifar, H., Deng, Y., Wu, L., Sarkar, D. 2016. Water treatment residual (WTR)-coated wood mulch for alleviation of toxic metals and phosphorus from polluted urban stormwater runoff. Chemosphere. https://doi.org/10.1016/j.chemosphere.2016.03.101.
- ↑ Na Nagara V., Sarkar D., Datta R. 2022. Phosphorus and Heavy Metals Removal from Stormwater Runoff Using Granulated Industrial Waste for Retrofitting Catch Basins. Molecules. https://doi.org/10.3390/molecules27217169
- ↑ Pinto, A. 2023. Combined Field and Laboratory Evaluation of the Performance of Multiple Bioretention Systems in Retaining Phosphorus in Urban Stormwater. Source to Stream Conference Presentation. https://sourcetostream.com/2023-track-1-day-1-pinto/
- ↑ Babatunde AO, Zhao YQ, Burke AM, Morris MA, Hanrahan JP. 2015. Characterization of aluminum-based water treatment residual for potential phosphorus removal in engineered wetlands. Environmental Pollution 157, 830-2836. doi: 10.1016/j.envpol.2009.04.016
- ↑ Wang JJ, Li T, Zhang Y. 2014. Water treatment residual as a bioretention media amendment for phosphorus removal. Huan Jing ke xue: Huanjing kexue 12:35, 4642-4647.