Design aspects and plant species affect pollutant removal in Southern California stormwater biofilters

B.K. Winfrey, M. Ho, W. Wang, Y-J Yong-Jun, R.F. Ambrose

Research output: Contribution to journalArticleResearchpeer-review


We conducted a column study to better understand the relative effects of plants, design elements, and operating
conditions on pollutant removal in stormwater biofilters in southern California under local conditions. We planted
five southern California native species (Baccharis pilularis, Carex praegracilis, Juncus patens, Leymus condensatus,
and Muhlenbergia rigens) in experimental biofilter columns fitted with a saturated zone and evaluated
pollutant removal during weekly dosing and following a 52-day dry period. Columns planted with C. praegracilis
and J. patens were also evaluated under conditions of fortnightly dosing and without the presence of a saturated
zone. During weekly dosing, planted columns had a total nitrogen removal efficiency of 46% on average whereas
removal was 8% in unplanted columns. B. pilularis and M. rigens performed better than other species at nitrogen
removal. The presence of a saturated zone improved nitrogen removal and metal removal, but only before the
52-day dry period. With a few exceptions, local best management practice effluent concentrations limits were
exceeded but performed similarly to existing southern California biofilters. Nitrogen removal decreased slightly
under a fortnightly dosing frequency, which better represented rainfall event frequency in Los Angeles when
compared to weekly dosing.
Original languageEnglish
Pages (from-to)300-317
Number of pages18
JournalBlue-Green Systems
Issue number1
Publication statusPublished - 2020


  • bioretention
  • California native plants
  • , green stormwater infrastructure
  • raingardens

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