Review of Dissolved Pollutants in Urban Storm Water and Their Removal and Fate in Bioretention Cells

TLDR

Storm‑water pollutants, especially the mobile dissolved phase, are a major driver of surface‑water degradation, yet most treatment focuses on particles, while low‑impact development bioretention systems infiltrate water to capture both dissolved and particulate pollutants. The authors review dissolved storm‑water pollutant sources, concentrations, removal mechanisms, and fate in bioretention cells for nutrients, toxic metals, and organic compounds. The review discusses bioretention design innovations—media amendments, saturated zones for denitrification, and vegetation—to enhance dissolved pollutant removal. Bioretention systems effectively capture dissolved and particulate pollutants, though knowledge gaps remain and future research directions are recommended.

Abstract

Storm-water pollutants are widely recognized as a major cause of surface water quality degradation. Most storm-water treatment efforts have focused on capture of particles and particle-associated pollutants, but oftentimes half or more of pollutant loads can be attributed to the dissolved phase. Dissolved pollutants are more mobile, bioavailable, and are captured via different mechanisms than particles. Low-impact development storm-water control measures such as bioretention are being used to infiltrate storm water to reduce storm-water volume as well as to capture storm-water pollutants. Bioretention systems have proven effective at capturing both dissolved and particulate storm-water pollutants. Herein the authors present a state-of-the-art review of dissolved storm-water pollutant sources and typical concentrations, removal mechanisms, and fate in bioretention cells covering three pollutant classes: (1) nutrients (i.e., phosphorus and nitrogen), (2) toxic metals, and (3) organic compounds, including emerging contaminants. Also discussed are recent innovations in bioretention design to enhance dissolved pollutant removal, such as media amendments, saturated zones for promoting denitrification, and vegetation for stimulating biodegradation. Current knowledge gaps and recommendations for future research directions are also discussed.