title: A unified look at phosphorus treatment using bioretention.
abstract: Phosphorus (P) is a water pollutant of significant concern as it limits the productivity of most freshwater systems, which can undergo eutrophication under heavy phosphorus inputs. Bioretention has shown great potential for stormwater quantity and quality control. However, phosphorus removal has been inconsistent in bioretention systems, with phosphorus leaching observed in some systems. This paper examines P removal mechanisms and performance in bioretention systems through published data. A temporal concept of P fate for different time-scales is proposed. A model is developed to predict effluent P concentrations (Ce) based on a media equilibrium concentration (Ceq) assumption, which is suitable for both short and long-term simulation. Ceq is well correlated with Ce for P data for different time-scales. Ceq varies less in media containing Al and Fe than in typical bioretention soil media. Although significant change in Ceq may occur during an event and long-term, Ceq variation in short-term is small. During the event and short terms, for high-P containing media, the concentration relationship is Ceq > Ce > C0 (influent P concentrations); for low-P containing media, Ceq < Ce < C0. During long-term, as media equilibrates with the influent runoff, Ceq ≈ Ce ≈ C0. The model explains concentration changes of P with depth. With proper selection of media and amendments, Ceq can be driven towards zero for P in bioretention media.
authors.affiliation: State Key Laboratory Base of Eco-hydraulic Engineering in Arid Area, Xi'an University of Technology, Xi'an, Shaanxi 710048, China.
authors.forename: Jiake
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, USA. Electronic address: apdavis@umd.edu.
authors.forename: Allen P
authors.initials: AP
authors.lastname: Davis
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D008962:Models, Theoretical; D010758:Phosphorus / Q000737:chemistry*; D011891:Rain; D012987:Soil / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D012987:Soil; D014874:Water Pollutants, Chemical; D010758:Phosphorus
keywords: Adsorption; Bioretention; Leaching; Mechanism; Model; Phosphorus; Stormwater management; Water treatment residual