Limited Bacterial Removal in Full-Scale Stormwater Biofilters as Evidenced by Community Sequencing Analysis

In urban areas, untreated stormwater runoff can pollute downstream surface waters. To intercept and treat runoff, low-impact or “green infrastructure” approaches such as using biofilters are adopted. Yet, actual biofilter pollutant removal is poorly understood; removal is often studied in laboratory...

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Bibliographic Details
Published in:Environmental science & technology 2021-07, Vol.55 (13), p.9199-9208
Main Authors: Li, Dong, Van De Werfhorst, Laurie C, Rugh, Megyn B, Feraud, Marina, Hung, Wei-Cheng, Jay, Jennifer, Cao, Yiping, Parker, Emily A, Grant, Stanley B, Holden, Patricia A
Format: Article
Language:English
Subjects:
Bacteria
Biofilters
Cores
Effluents
Green infrastructure
Influents
Markers
Microorganisms
Pollutant removal
Pollutants
Rhizosphere
rRNA 16S
Runoff
Sediment pollution
Sequence analysis
Sewage
Soil bacteria
Soil contamination
Soil microorganisms
Soil pollution
Soil surfaces
Soils
Storm runoff
Stormwater
Stormwater management
Surface runoff
Surface water
Treatment and Resource Recovery
Unsteady flow
Urban areas
Urban runoff
Water inflow
Water pollution
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Summary:In urban areas, untreated stormwater runoff can pollute downstream surface waters. To intercept and treat runoff, low-impact or “green infrastructure” approaches such as using biofilters are adopted. Yet, actual biofilter pollutant removal is poorly understood; removal is often studied in laboratory columns, with variable removal of viable and culturable microbial cell numbers including pathogens. Here, to assess bacterial pollutant removal in full-scale planted biofilters, stormwater was applied, unspiked or spiked with untreated sewage, in simulated storm events under transient flow conditions, during which biofilter influents versus effluents were compared. Based on microbial biomass, sequences of bacterial community genes encoding 16S rRNA, and gene copies of the human fecal marker HF183 and of the Enterococcus spp. marker Entero1A, removal of bacterial pollutants in biofilters was limited. Dominant bacterial taxa were similar for influent versus effluent aqueous samples within each inflow treatment of either spiked or unspiked stormwater. Bacterial pollutants in soil were gradually washed out, albeit incompletely, during simulated storm flushing events. In post-storm biofilter soil cores, retained influent bacteria were concentrated in the top layers (0–10 cm), indicating that the removal of bacterial pollutants was spatially limited to surface soils. To the extent that plant-associated processes are responsible for this spatial pattern, treatment performance might be enhanced by biofilter designs that maximize influent contact with the rhizosphere.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.1c00510