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Removal of Escherichia coli in Stormwater Biofilters

Removal of Escherichia coli in Stormwater Biofilters

Titel: Removal of Escherichia coli in Stormwater Biofilters
Kategorie: Diverses
Datum: 29. Nov. 2011, 11:00 Uhr - 12:00 Uhr
Ort: Eawag Dübendorf
  Forum Chriesbach C24
Referenten: Dr. David McCarthy, Monash University, Melbourne (Australia)
Leitung: Christoph Ort, SWW, Eawag Dübendorf
Organisation: Christoph Ort, SWW
Kosten: keine
Download: als Kalender-Eintrag


It is well documented that urban stormwater is contaminated with a number of pollutants and therefore needs to be treated before it can be safely harvested. Stormwater biofilters are a low energy treatment technology established under Water Sensitive Urban Design. The capacity of these biofilters in removing various stormwater pollutants which impact ecosystem health, such as sediment, heavy metals and nutrients have been researched to a greater extend compared with other pollutants which adversely impact human health, especially human pathogens. The few studies which have evaluated the microorganism removal capacity of biofilters have shown a wide range of performances, from net export to very high removal. In order to promote biofilters as effective stormwater treatment options, especially for stormwater harvesting applications, it is important to understand what processes (or operational conditions) drive this variability and determine whether certain design elements can be optimised to improve their overall performance. Hence, this study investigated the effects of particle-microbial interaction, inflow concentration, background microbial concentration and various design factors (such as plant presence and type and the presence of a submerged anoxic zone) on microbial removal capacity.

The experimental methods consisted of a biofilter column study to evaluate removal performance and a sequential filtration procedure to estimate microbial partitioning. Columns were dosed with different concentrations of E. coli spiked into semi-natural stormwater. The results indicate that the microbial removal is significantly affected by inflow concentration and background microbial levels. Outflow concentrations increased with increasing inflow concentrations for both applications. Leaching was observed when a low concentration inflow event occurred after a very high concentration inflow event. Lomandra longifolia showed better removal  compared to Carex appressa.

More details: Dr. David McCarthy

Water sensitive cities