H13J-1717
Treating Stormwater with Green Infrastructure: Plants, Residence Time Distributions, and the Removal of Fecal Indicator Bacteria
Monday, 14 December 2015
Poster Hall (Moscone South)
Emily Parker1, Stanley Baugh Grant2, Megan Rippy1, Brandon Winfrey3 and Andrew Mehring4, (1)University of California Irvine, Irvine, CA, United States, (2)University of California Irvine, Civil and Environmental Engineering, Irvine, CA, United States, (3)University of California Los Angeles, Los Angeles, CA, United States, (4)University of California San Diego, La Jolla, CA, United States
Abstract:
In many cities, green infrastructure is increasingly used to capture and treat stormwater runoff, due to the many opportunities these systems afford for protecting receiving water quality and ecology while mitigating water scarcity. Here, we focus on how plants affect the removal of fecal indicator bacteria (FIB) in newly-constructed stormwater biofilters, a type of green infrastructure consisting of unconsolidated granular media containing one or more plant species. Input-response experiments were carried out using both non-reactive (salt) and reactive (sewage) tracers on six laboratory-scale (~1m long by 24 cm diameter) biofilters, half of which were planted with the sedge Carex appressa (treatment replicates) and half of which were unplanted (control replicates). C. appressa modifies the residence time distribution (RTD) in a biofilter by creating preferential flow paths along which water and mass can move quickly, but does not appear to alter the intrinsic rate at which FIB are removed. Thus, the “green” component of green infrastructure can alter pollutant removal by changing the RTD, with or without a concomitant change in pollutant reactivity.
