Citation:

Ament, M., E. Roy, Y. Yuan, AND S. Hurley. Phosphorus Removal, Metals Dynamics, and Hydraulics in Stormwater Bioretention Systems Amended with Drinking Water Treatment Residuals. Journal of Sustainable Water in the Built Environment. American Society of Civil Engineers (ASCE), New York, NY, 8(3):04022003, (2022). https://doi.org/10.1061/JSWBAY.0000980

Impact/Purpose:

Water bodies and coastal areas around the world are threatened by excessive amounts of nitrogen (N) and phosphorous (P) from upstream watersheds, which can cause rapid proliferation of algae. These algal blooms negatively impact drinking water sources, aquatic species, and recreational services of water bodies by producing toxins, also called harmful algal blooms (HABs). Finding ways reducing N and P losses from stormwater runoff is paramount important for EPA program offices and regional partners to make informed decisions to better control nutrient losses from landscape including urban.

Description:

Drinking water treatment residuals (DWTRs) are a promising media amendment for enhancing phosphorus (P) removal in bioretention systems, but substantial removal of dissolved P by DWTRs has not been demonstrated in field bioretention experiments. We investigated the capacity of a nonamended control media (control) and a DWTR-amended treatment media (DWTR) to remove soluble reactive P (SRP), dissolved organic P (DOP), particulate P (PP), and total P (TP) from stormwater in a 2-year roadside bioretention experiment. Significant reductions in SRP, PP, and TP concentrations and loads were observed in both the control and DWTR media. However, the P removal efficiency of the DWTR cells was greater than those of the control cells for all P species, particularly during the second monitoring season because P sorption complexes likely began to saturate in the control cells. The difference in P removal efficiency between the control and DWTR cells was greatest during large storm events, which transported the majority of dissolved P loads in this study. We also investigated the potential for DWTRs to restrict water flow through bioretention media or leach heavy metals. The DWTRs used in this study did not affect the hydraulic performance of the bioretention cells and no significant evidence of heavy-metal leaching was observed during the study period. Contrasting these results with past studies highlights the importance of media design in bioretention system performance and suggests that DWTRs can effectively capture and retain P without affecting system hydraulics if properly incorporated into bioretention media.

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