Can we use a simple modelling tool to validate stormwater biofilters for herbicides treatment?

• Published in: Urban water journal Vol. 16; no. 6; pp. 412 - 420
• Main Authors: Zhang, Kefeng, Randelovic, Anja, Deletic, Ana, Page, Declan, McCarthy, David T.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03.07.2019; Taylor & Francis Ltd
• Subjects: Adsorption; Atrazine; Biodegradation; Biofilters; Evaporation; Glyphosate; Herbicides; Kinetics; Laboratories; Organic carbon; Organic soils; Outflow; Parameter estimation; Pollutant removal; predictive uncertainties; Simazine; Soil; Soil water; Stormwater; stormwater biofilter treatment model (MPiRe); Treatment validation; Water outflow
• ISSN: 1573-062X; 1744-9006
• DOI: 10.1080/1573062X.2018.1508593

This study proposes a new stormwater biofilter validation approach, using a process-based model of micropollutant removal in stormwater biofilters. The model performance was assessed against in-situ challenge tests conducted on a field biofilter under challenging operational conditions for removing four herbicides (atrazine, simazine, prometryn and glyphosate). Two-site adsorption kinetics were used on the laboratory results to estimate parameters; the estimated K oc (soil organic carbon-water partitioning coefficient) corresponded well with literature values, while f e (instantaneous adsorption fraction) and α k (kinetic adsorption rate) differed from the literature. The agreement between modelled outflow concentrations and in-situ challenge tests was good for prometryn (Nash-Sutcliffe coefficient, E = 0.60) and moderate for glyphosate (E = 0.45), with up to 20% over-prediction of peak outflow concentrations. Poor performance were found for atrazine and simazine (E = 0.30). The prediction uncertainties were bigger after long dry periods, which was attributed to complex processes (biodegradation and evaporation) not captured in either the laboratory column experiments or the model.