A unified look at phosphorus treatment using bioretention

Area of Science:

• Environmental Science
• Water Quality Management
• Soil Science

Background:

• Phosphorus (P) is a major freshwater pollutant, causing eutrophication.
• Bioretention systems are used for stormwater control but show inconsistent P removal.
• Phosphorus leaching from bioretention media is a concern.

Purpose of the Study:

• To examine P removal mechanisms and performance in bioretention systems.
• To propose a temporal concept of P fate in bioretention.
• To develop a model for predicting effluent P concentrations (Ce) using media equilibrium concentration (Ceq).

Main Methods:

• Review of published data on P removal in bioretention systems.
• Development of a model based on media equilibrium concentration (Ceq).
• Analysis of P concentration dynamics over different time scales (event, short-term, long-term).

Main Results:

• A model correlating Ceq with Ce was developed and validated across time scales.
• Ceq is more stable in media with Aluminum (Al) and Iron (Fe) amendments.
• The model explains P concentration changes with depth in bioretention media.

Conclusions:

• The proposed model accurately predicts effluent P concentrations in bioretention systems.
• Media selection and amendments can minimize P leaching by driving Ceq towards zero.
• Optimized bioretention design can enhance P removal and mitigate freshwater eutrophication.