Abstract:
Stormwater biofilters manage quantity and
quality of urban stormwater runoff. Particulate solids
from natural and anthropogenic sources accumulate on
paved surfaces and eventually reach receiving waters.
Retention of suspended solids in stormwater manage ment systems ensures the quality of stormwater runoff to
water resources. Stormwater biofilters are similar in
most of design parameters to sand filters employed in
water treatment systems. The understanding and design
of stormwater biofilters are often based on generic
models of sand filters. Unlike water treatment sand
filters, which are continuously fed, stormwater biofilters
operate intermittently with spontaneously alternating
wetting and drying cycles. This results in dynamic pol lutant removal pattern that employs different mecha nisms during and across rainfall events. As such, pilot
scale biofilter columns fabricated with a layer of organic
material were operated. Removal of suspended solids
was very dynamic, where impact of age of filter, ante cedent dry days, and inflow quality varied during and
across events. Flush of retained solids and filter material
occurred during the stabilisation period during each
event while very high removal percentages (more than
90%) were observed after stabilisation, during an event.
Clogging was not observed due to re-entrainment, re distribution, and flush of retained solids during intermit tent wetting and drying cycles.
