High-Flow Structural Media for Removing Stormwater-Dissolved Phosphorous in Permeable Paving

Abstract

Phosphorus (P) loadings from urban runoff is a persistent contributor to waterbody impairment. Dissolved phosphorus (DP), however, is not well retained by many stormwater control measures (SCMs), including permeable pavements. This study seeks to evaluate a novel base material developed to enhance P removal in permeable paving. The media has high hydraulic conductivity, 9.0×10−4±1.9×10−5 m/s (324±6.8 cm/h), and is structurally suitable as a permeable pavement base. It demonstrated long-term DP adsorption capacity and achieved treatment above 90% total DP removal for the first 50 m of applied water, beyond the typical pavement design lifetime, with no contributing area. This indicates potential application of permeable pavement to treat run-on at loading rates of 5∶1 or possibly higher. Adsorption to aluminum (hydr)oxides is thought to be the primary mechanism for DP retention. DP uptake is described by a first-order steady-state plug flow model developed and fit to experimental data. This novel media has the potential to improve P retention in permeable pavement and enable run-on treatment.