Environmental Engineering Reference
In-Depth Information
registered during the event, times the measured contaminant event mean concentra-
tions (C
i
). Site mean concentrations (SMC) for each specific contaminant were
calculated as the accumulated load over accumulated stormwater volume, such as
SMC = SM
i
/SV
i
. Based on the calculated SMC for the inlet (SMC
in
) and the outlet
(SMC
out
), the removal efficiency R (%) was calculated according to the following
expression:
SMC
−
SMC
×
(1)
R
=
in
out
100
SMC
in
Results and Discussion
The concentration of total suspended solids, nutrients, heavy metals and PAH at the
inlet and outlet of the Järnbrott stormwater pond is illustrated in Fig.
1
for the three
storm events. The measurements exhibited a clear reduction of total suspended solids
(TSS) and total phosphorous (Tot-P) was observed, while no reduction was seen for
nitrate (NO
3
-N) and total nitrogen (Tot-N). As indicated in error bars, the concen-
trations of nitrate varied highly between the three events. For the metals in Fig.
1b
represented by cadmium (Cd), copper (Cu) and lead (Pb), a reduction was observed
in the pond, although lower for cadmium compared to the others. The concentration
of poly-aromatic hydrocarbons decreased in the stormwater pond, as repre-
sented by the accumulated concentrations of the 16 EPA-PAH shown in Fig.
1b
.
a
b
TSS
NO3-N
Tot-N
To t-P
Cd
Cu
Pb
16 PA H:h
2
2
1
1
0
0
-1
-1
-2
-2
Inlet
Outlet
Inlet
Outlet
Fig. 1
Event mean concentrations (log-values) of (
a
) suspended solids, nitrogen compounds and
total phosphorous, and (
b
) metals and PAH measured at inlet and outlet of the stormwater pond.
Median concentrations for the three storm events are given with min and max in
error bars
