Denmark's National Inventory Report 2005 - Submitted under the ...

Methodology – Indirect emissions - from sewage effluents
The IPCC default methodology only includes N 2 O emissions from human sewage based on annual
per capita protein intake. The methodology only accounts for nitrogen intake, i.e. faeces and urine
and neither the industrial nitrogen input nor non-consumption protein from kitchen, bath and
laundry discharges are included. The default methodology used for the ten per cent of the Danish
population that is not connected to the municipal sewage system, is multiplied by a factor 1.75 to
account for the fraction of non-consumption nitrogen (Sheehle and Doorn, 1997). For the remaining
90 % of the Danish population national activity data on nitrogen in discharge wastewater is
available. This data is used in combination with the default methodology for the ten per cent of the
Danish population not connected to the municipal sewer system. The effluent N load is added 10
per cent to account for the WWTPs not included in the statistics (DEPA 1994, 1996, 1997, 1998,
1999, 2001, 2002 and 2003). The formula used for calculating the emission from effluent WWTP
discharges is:
206
(
where
2
,
,
=
[ ( 3 ⋅ ) ⋅ 1 ⋅ ) ⋅ ) ) + ( ' + ( ' ⋅ 0.
1 ) ]
,
,
⋅ ()
2,
,
0
⋅
2 ⋅ 0
P is the annual protein per capita consumption per person per year.
F N is the fraction of nitrogen in protein. i.e. 0.16 IPCC GL, p 6.28
N pop is the Danish population
F nc is the fraction of the Danish population not connected to the municipal sewer system, i.e. 0.1
F is the fraction of non-consumption protein in domestic wastewater. i.e. 1.75 (Sheehle and Doorn,
1997)
D N.WWTP is the effluent discharged sewage nitrogen load (added ten per cent to account for data not
included in the statistics)
EF N2O.WWTP.effluent is the IPCC default emission factor of 0.01 kg N 2 O-N/kg sewage-N produced (IPCC
GL, p 6.28)
M N2O and M N2O are the mass ratio i.e. 44/28 to convert the discharged units in mass of total N to
emissions in mass N 2 O
Activity data used for calculation of the indirect N 2 O emission
In Table 8.18 activity data is referring to D N, WWTP , the effluent discharged nitrogen load.
Table 8.18. Discharges* of nitrogen from point sources [tonnes].
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Separate industrial discharges 2574 2737 2471 1729 1800 1428 863 897 812 752 509
Rainwater conditioned effluent 921 882 1025 1207 867 629 800 968 975 762 758 1005 685
Scattered houses 1280 1210 1141 1143 1123 997 972 979 1005 968 957
Mariculture and fish farming 1737 1684 1735 1543 1494 1241 1418 2714 1757 1487 1162
Municipal and private WWTPs 16884 15111 13071 10787 10241 8938 6387 4851 5162 5135 4653 4221 4528 3614
*It should be mentioned that it is not possible to estimate any direct emissions from industrial on-site wastewater treatment processes.
8.3.4 Uncertainties and time-series consistency
The parameters considered in the uncertainty analyses and the estimated uncertainties of the parameters
are shown in Table 8.19. For all uncertainties symmetric values based on maximum numeric
value are estimated (cf. e.g. section 8.2.3.1 of this chapter).
2