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Retention and survival of E. coli in stormwater biofilters: role of vegetation, rhizosphere microorganisms and antimicrobial filter media

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journal contribution
posted on 2017-05-01, 00:00 authored by G I Chandrasena, M Shirdashtzadeh, Yali Li, A Deletic, J M Hathaway, D T McCarthy
© 2017 Elsevier B.V. The public health risks associated with pathogens in urban stormwater have been well established, making it necessary to ensure adequate treatment of the stormwater before it is discharged into recreational water bodies or is harvested for reuse. Biofilters, also known as stormwater bioretention systems or raingardens, have shown promising, yet variable, results in reducing indicator bacteria in stormwater. Different biofilter design elements, such as filter media composition and vegetation type, have been found to cause this variable removal performance. Although plants play a key role in the treatment of pollutants, relatively little work has been conducted to understand the importance of interactions between vegetation and the biofilter microbial community on fecal microbial removal. A laboratory-scale biofilter experiment was conducted using Escherichia coli as the test fecal microorganism. Biofilter columns with differing soil media and vegetation types were dosed over a two month span, during which inflow and outflow samples were collected to evaluate system performance. The columns were then decommissioned to collect rhizosphere and bulk soil samples. Root exudates were extracted and used in an E. coli survival study to evaluate their contribution to system performance. The study demonstrated that the antagonistic effects of root exudates/rhizosphere microbes and Cu2+ exchanged zeolite antimicrobial filter media adversely impact the survival of E. coli retained within stormwater biofilters. Furthermore, leaf and flower/seed extracts of L. continentale showed some potential antibacterial activity against E. coli. This work supports the concept that natural processes in biological systems can deliver effective results in the removal of fecal microorganisms, and should be promoted to the extent possible in stormwater green infrastructure.

History

Journal

Ecological engineering

Volume

102

Pagination

166 - 177

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0925-8574

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2017, Elsevier B.V.