Environmental Engineering Reference
In-Depth Information
to wastewaters. In the Netherlands, 8.3% of all prescribed medicines are never
consumed, and only 3% of these end up in the sewer (Blom et al. 1995). The majority
of unused medicines are returned to pharmacies. Nevertheless, one-third (33%) of liquid
medicines returned to pharmacies end up in the sewer (Blom et al. 1995).
The fate of excreted veterinary drugs differs considerably from the fate of those
excreted by humans (Mons et al. 2000). In general, municipal sewage and, therefore,
human pharmaceuticals will pass through a STP prior to entering rivers, streams, or
the coastal zone. Veterinary drugs are more likely to contaminate soil and ground
water (without previous waste water treatment), when liquid manure is applied to
the soil as fertilizer. It is assumed that veterinary pharmaceuticals will reach surface
waters only after runoff (Mons et al. 2000).
Other means by which pharmaceuticals reach the coastal and marine environment
are atmospheric deposition and sea-shipping emissions. The emission of pharma-
ceuticals to the atmosphere is mentioned in one study only (Hamscher et al.
2002). The exact extent (size) of this source is unknown, but Boxall et al. (2003)
estimated that this source is of minor importance compared to other environ-
mental input sources. Therefore, atmospheric deposition, as an input source of
pharmaceuticals to the DCZ, is not included in this study.
Although some pharmaceuticals (e.g., the antibiotic tetracycline) are mentioned
as possible antifouling paint additives (Peterson et al. 1993), a literature search by
Klijnstra (2005) found no commercially available antifouling products that con-
tained pharmaceuticals. Hence, sea-shipping emissions, as input source of pharma-
ceuticals to water of the DCZ, are not considered in this study.
2.2
Load Calculations
The load of a specific pharmaceutical and/or metabolite transported by rivers, sew-
age effluent, or industrial effluent to the Netherlands (from neighboring countries)
and to the DCZ is calculated according to the following equations:
12
L
−
sw
=
(
Q
×
C
+
Q
×
C
+
Q
×
C
)
×
f
/ 10
(1)
in
a
EYS
a
LOB
a
SOD
in
EYS
LOB
SOD
L
−
sw
=
(
Q
×
C
+
Q
×
C
+
Q
×
C
)
×
f
/ 10
12
(2)
out
a
AND
a
MAA
a
HAR
out
AND
MAA
HAR
L
−
sew
=
Q
×
C
/ 10
12
(3)
out
a
SEW
SEW
12
L
−
ind
=
Q
×
C
/ 10
(4)
out
a
IND
IND
where
L
-sw
in
= Load of pharmaceuticals entering the Netherlands with surface water in
2002 (t yr
−1
).
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