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