title: Validation of stormwater biofilters using in-situ columns.
abstract: Stormwater harvesting biofilters need to be validated if the treatment is to be relied upon. Currently, full-scale challenge tests (FCTs), performed in the field, are required for their validation. This is impractical for stormwater biofilters because of their size and flow capacity. Hence, for these natural treatment systems, new tools are required as alternatives to FCT. This study describes a novel in-situ method that consists of a thin stainless steel column which can be inserted into constructed biofilters in a non-destructive manner. The in-situ columns (ISCs) were tested using a controlled field-scale biofilter where FCT is possible. Fluorescein was initially used for testing through a series of continuous applications. The results from the ISC were compared to FCT conducted under similar operational conditions. Excellent agreement was obtained for the series of continuous fluorescein experiments, demonstrating that the ISC was able to reproduce FCT results even after extended drying periods (Nash-Sutcliffe coefficient between the two data sets was 0.83-0.88), with similar plateaus, flush peaks, slopes and treatment capacities. The ISCs were then tested for three herbicides: atrazine, simazine and prometryn. While the ISC herbicide data and the FCT data typically matched well, some differences observed were linked to the different climatic conditions during the ISC (winter) and FCT tests (summer). The work showed that ISC is a promising tool to study the field performance of biofilters and could be a potential alternative to full scale challenge tests for validation of stormwater biofilters when taking into account the same inherent boundary conditions.
authors.affiliation: Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Rd, Clayton, VIC 3800, Australia; CRC for Water Sensitive Cities, Melbourne, VIC 3800, Australia. Electronic address: kefeng.zhang860225@gmail.com.
authors.forename: Kefeng
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Rd, Clayton, VIC 3800, Australia; CRC for Water Sensitive Cities, Melbourne, VIC 3800, Australia; URGC Hydrologie Urbaine, INSA Lyon, Bâtiment Coulomb, 34 avenue des Arts, 69621 Villeurbanne Cedex, France.
authors.forename: Valentin
authors.initials: V
authors.lastname: Valognes
authors.affiliation: CSIRO Land and Water Research Flagship, Waite Laboratories, Waite Rd., Urrbrae, SA 5064, Australia.
authors.forename: Declan
authors.initials: D
authors.lastname: Page
authors.affiliation: Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Rd, Clayton, VIC 3800, Australia; CRC for Water Sensitive Cities, Melbourne, VIC 3800, Australia.
authors.forename: Ana
authors.initials: A
authors.lastname: Deletic
authors.affiliation: Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Rd, Clayton, VIC 3800, Australia; CRC for Water Sensitive Cities, Melbourne, VIC 3800, Australia; Environmental and Public Health Microbiology Laboratory, Department of Civil Engineering, Monash University, VIC 3800, Australia.
authors.forename: David
authors.initials: D
authors.lastname: McCarthy
mesh_terms: D005374:Filtration / Q000379:methods*; D011891:Rain; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Herbicides; In-situ column; Potable end-use; Stormwater biofilters; Stormwater harvesting; Treatment validation