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→External Performance Resources
==External Performance Resources==
==External Performance Resources==
*[https://www3.epa.gov/region1/npdes/stormwater/research/epa-final-report-filter-study.pdf USEPA, 2013 - Evaluation and Optimization of Bioretention Design for Nitrogen and Phosphorus Removal]
*[https://www3.epa.gov/region1/npdes/stormwater/research/epa-final-report-filter-study.pdf (USEPA, 2013) - Evaluation and Optimization of Bioretention Design for Nitrogen and Phosphorus Removal]
**USEPA conducted both field and laboratory testing on the performance of bioretention with augmented designs and filter media composition with aluminum hydroxide/oxide content, found normally within water treatment residuals. These additives added at 10-15% of the total filter media mix ad median removal efficiencies of 90-99% of orthophosphate and a second study found a bioretention design with WTR mixture in the filter media and a [[Bioretention: Internal water storage|IWSZ]] optimized to remove phosphorus and nitrogen had a removal efficiency of 20% and effluent concentrations below 20µg/L (well below the MECP/CCME guideline in Ontario).
**USEPA conducted both field and laboratory testing on the performance of bioretention with augmented designs and filter media composition with aluminum hydroxide/oxide content, found normally within water treatment residuals. These additives added at 10-15% of the total filter media mix ad median removal efficiencies of 90-99% of orthophosphate and a second study found a bioretention design with WTR mixture in the filter media and a [[Bioretention: Internal water storage|IWSZ]] optimized to remove phosphorus and nitrogen had a removal efficiency of 20% and effluent concentrations below 20µg/L (well below the MECP/CCME guideline in Ontario).
*[https://www.mdpi.com/2073-4441/14/3/396 (Ho and Lin, 2022) - Pollutant Removal Efficiency of a Bioretention Cell with Enhanced Dephosphorization]
**Authors Ho and Lin, 2022 note that bioretention practices perform poorly in reducing phosphorus from influent stormwater when compared to their ability to remove ammonia and COD pollutants. The authors tested a new type of enhanced dephosphorization bioretention cell (EBC) which improves phosphorus removal performance. The difference between EBC and a traditional bioretention cell is that the lowest level of an EBC feature is comprised of a mixed fill material layer (permeable layers - PLs and soil mixed layers - SMLs) instead of a traditional gravel bed layer. The SMLs include active charcoal powder, organic matter and iron, evenly spaced apart, while the PLs include aggregates of gravel, pumice and zeolite. Over the two years that the same sized EBC feature was monitored in comparison to a standard bioretention cell they found that the EBC outperformed the traditional bioretention cell by removing 92% of total phosphorus to 52%. The average inflow concentration for both features from May 2019 - April 2021 was 0.76 mg/L, whereas the outflow concentration averages were 0.36 mg/L for the traditional bioretention cell and 0.06 mg/L for the EBC, respectively.
[[File:EBC vs. TBC.PNG|400px|thumb| Comparison of an Enhanced dephosphorization bioretention cell (EBC) (above) vs. a traditional bioretention cell (TBC) (below). The EBC includes evenly spaced apart soil mixture layers, which includes 70-80% native soil found on site mixed with 20-30% of charcoal, oregani matter and iron, along with permeable layers of gravel pumice and zeolite, all of which help adsorb phosphates out of stormwater entering the system. This differs from the TBC design which generally includes just a gravel bed to aid in the facility's drainage ability (Ho and Lin, 2022)<ref>Ho, C.C. and Lin, Y.X., 2022. Pollutant Removal Efficiency of a Bioretention Cell with Enhanced Dephosphorization. Water, 14(3), p.396. https://mdpi-res.com/books/book/5900/Urban_Runoff_Control_and_Sponge_City_Construction.pdf?filename=Urban_Runoff_Control_and_Sponge_City_Construction.pdf#page=168</ref>]].
==References==
==References==