Water Treatment Residual as a Bioretention Amendment for Phosphorus. II: Long-Term Column Studies

Abstract

Bioretention is an EPA-designated best management practice developed to mitigate negative ecological effects from urban storm-water. However, while these facilities perform well for the removal of a multitude of pollutants, in many cases they are ineffective in treating excessive storm-water nutrients such as phosphorus (P) that may induce surface water eutrophication. This work builds on the results of a previous paper, which describe initial studies on the use of aluminum-based water treatment residual (WTR) as a bioretention soil media (BSM) amendment. A 5% WTR-, 3% triple-shredded hardwood bark mulch-amended loamy sand BSM was investigated in a large-scale (0.9 m) column to determine the media P adsorption performance under varying hydrologic and pollutant concentration conditions. Results indicate that the WTR-amended media adsorbed 88.5% of the applied P mass, relative to a non-WTR-amended control media for which effluent P mass increased by 71.2%. The amended media consistently produced total phosp...