LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 6C: POULTRY AND PORK PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
lysed from the moment the slurry is excreted by pigs until 10 years after field application. The environmental
impact categories that are included in the analysis are the climate change potential, including CO2 (both biogenic
and non-biogenic), CH4 and N2O, acidification potential, including NH3, freshwater eutrophication
potential, including P, and marine water eutrophication potential, including NO3 - and NH3. ReCiPe2008 is
used for analysis of environmental impact potentials (Goedkoop et al., 2009).
2.2. Scenarios
For this LCA, it is assumed that the pigs are raised in Denmark, and that they consume an average Danish
feed composition. The pigs are housed in pig housing with partially-slatted flooring. All liquid manure
(slurry and liquid fraction) is assumed to be stored in a covered tank. Storage of the solid fraction is covered
to reduce self-heating, and compost is well aerated. Liquid manure is applied by trailing hose to fields around
the farm, with an average distance of 8 km from storage. It is assumed that liquid manure is a substation for
mineral nitrogen fertiliser (ammonium nitrate). Solid fractions are transported to areas where phosphorus is
needed, over an average distance of 100 km. As farmers on these fields with low phosphorus status would
normally apply mineral phosphorus fertiliser, it is assumed that the solid fraction is a substitution for mineral
phosphorus (single superphosphate) and nitrogen (ammonium nitrate) fertiliser. Phosphorus losses from the
soil are calculated as a proportion of the difference between the phosphorus that is applied as fertiliser, and
the average phosphorus need that plants have (assumed to be 21.5 kg P ha -1 yr -1 ). If less phosphorus is applied
than plants take up, a negative freshwater eutrophication potential results. Solid fractions are applied by
broadcast spreading followed by rapid incorporation. Main emission factors are provided in Table 1.
Four treatment scenarios were compared to a reference scenario:
Reference Scenario – Conventional manure management in the form of slurry, with in-house storage
of 6 weeks, covered out-house storage for 6 months, and field application with a trailing hose
Screw Press Scenario – Slurry separation with a mechanical screw press, with donor farm application
of the liquid fraction, and transportation to and application on a recipient farm of the solid fraction
Screw Press with Composting Scenario – As Screw Press Scenario with the difference that the solid
fraction is windrow composted before transportation to recipient farm
Decanter Centrifuge Scenario – Slurry separation with a decanter centrifuge, with donor farm application
of the liquid fraction, and transportation to and application on recipient farm of the solid fraction
Decanter Centrifuge with Ammonia Stripping Scenario – As Decanter Centrifuge Scenario with the
difference that ammonia is stripped from the liquid fraction resulting in a compact nitrogen fertiliser
Table 1: LCI parameters used for in-house storage, ex-house storage and field application.
NH3-N N2O-N N2-N -
NO3 -N Degradation CH4-C CO2-C MFE
kg/kg TAN-N kg/kg N kg/kg N kg/kg N kg/kg OM kg/kg OM deg. kg/kg OM deg. %
House 0,250 0,185 0,150 0,310
Storage
slurry / liquid 0,013 0,185 0,230 0,230
solid 0,003 0,002 0,004 0,070 0,230 0,230
compost 0,004 0,008 0,024 0,600 0,060 0,400
reject 0,950
Field application
slurry 0,160 0,020 0,041 0,395 75
liquid 0,120 0,020 0,038 0,405 85
solid 0,390 0,020 0,038 0,332 65
compost 0,390 0,020 0,050 0,304 45
reject 0,950 0,020 0,038 0,405 85
NH 3 -fration 0,020 0,020 0,025 0,418 100
min. fertilizer 0,027 0,020 0,024 0,407 100
TAN = total ammoniacal nitrogen, OM = organic matter, reject is the liquid fraction after ammonia stripping,
NH3-fraction is the ammonia-rich fraction after ammonia stripping.
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