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

ABSTRACT

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.

KEYWORDS:

• Treatment validation
• predictive uncertainties
• stormwater biofilter treatment model (MPiRe)

Acknowledgements

This study was funded by CRC for Water Sensitive Cities and Chinese Scholarship Council (CSC) (Grant no. 2011609012). The authors also wish to acknowledge Christelle Schang, Gayani Chandrasena, Yali Li, Frank Winston and Richard Williamson for their assistance during the experiments and Monica Sanders for her professional language proof reading.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplementary data for this article can be accessed here.

Additional information

Funding

This work was supported by the Chinese Scholarship Council (CSC) [2011609012];CRC for Water Sensitive Cities.