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A Novel Physical Technique for E. Coli Removal from Stormwater
Citation:
TUCCILLO, M. E. A Novel Physical Technique for E. Coli Removal from Stormwater. Presented at EPA Science Forum, Washington, DC, May 20 - 22, 2008.
Impact/Purpose:
to present information
Description:
In addition to heavy metals and polymeric aromatic hydrocarbons(PAHs), pathogens such as E.Coli contribute to the overall pollutant load in urban stormwater runoff. A number of constructed landscape features, collectively known as structural best management practices (BMPs) are employed to treat contaminated runoff. The majority of structural BMPs rely exclusively on physical separation processes such as sedimentation for treatment. Although BMPs remove a large fraction of suspended solids and associated pollutants, a significant amount of E. coli is not removed. In a previous in-house study, generic hardwood mulch was used to remove dissolved heavy metals and PAHs from contaminated stormwater runoff. In the work presented here, hardwood mulch was used to remove E.coli from stormwater runoff. Stormwater contaminated with E. coli was agitated at ambient conditions with hardwood mulch. The clear supernatant was withdrawn at specific time intervals. The pH and temperature were noted, and the supernatant was analyzed for E. coli. The mulch was then filtered and washed with distilled water followed by dilute hydrochloric acid (pH 4) to remove sorbed E.coli cells. After washing, the mulch was filtered under gentle suction. The pH and temperature of the filtrate were recorded, and the E.coli content was analyzed. After 10 minutes of contact with the stormwater, the mulch had removed from the stormwater an average of at least 1.36 X 106 CFU of E.coli per gram of dry mulch. Mulch appears to be an improvement over existing stormwater disinfection techniques and further studies are underway.