Life Cycle Assessment of Slurry Management Technologies
Annex C. Samson Bimatech Mechanical Separation – Life Cycle Inventory data
- C.1 System description
- C.2 In-house storage of slurry
- C.3 Storage of slurry in pre-tank
- C.4 Samson Bimatech Mechanical Separation
- C.5 Outdoor storage of the liquid fraction
- C.6 Transport of the liquid fraction to field
- C.7 Field processes (liquid fraction)
- C.8 Avoided mineral fertilisers
C.1 System description
This appendix contains Life Cycle Inventory data for the Samson Bimatech mechanical separation plant. The separation plant separates pig or cattle slurry in a fibre fraction and a liquid fraction (“reject”). The fibre fraction is normally regarded as the “primary product” of the separation process.
The fibres are either combusted in the Samson Bimatech Energy Plant (Annex D) or they might be transported to central biogas plants, where the main part of the carbon content is used for biogas production (Annex G of an upcoming report following this).
The liquid fraction is pumped to an outdoor storage tank and applied to fields without further treatment.
The Samson Bimatech mechanical separation plant has not yet been tested on cattle slurry. It is scheduled to be April/May 2009. Accordingly, this appendix only includes data on pig slurry.
Stirring and pumping of slurry occurs in and between some of the processes. Stirring and pumping is not shown in the flow diagram in figure C.1 but the energy consumption for stirring and pumping is included in the model as in Annex A.
It should be emphasized that this Annex is not a full “scenario”. The fibre fraction continues in other Annexes (Annex D, Annex E and further biogas-annexes in the upcoming report). A full “scenario” follows the liquid fraction and the fibre fraction to the end – and this annex only covers the liquid fraction.
Figure C.1: Flow diagram for the Samson Bimatech Mechanical Separation.
C.2 In-house storage of slurry
The assumptions and Life Cycle Inventory data for the storage of slurry in the housing units are the same as for the reference scenario, see Annex A.
C.3 Storage of slurry in pre-tank
From the housing units, the slurry is flushed (or run by itself) from the slurry space under the column floor to an outdoor pre-tank, typically with top level just below the floor level in the housing units.
In the reference scenario, the emissions from storage of slurry in the indoor slurry space, the pre-tank and emissions from the outdoor storage are calculated together, as this is the way it is done in the literature references that have been available, see Annex A.
For this scenario, separate emission data from the pre-tank is needed as the slurry is separated, and as it is only part of the slurry that is stored outdoor (i.e. the liquid fraction). However, it has not been possible to identify the relative contribution of the emissions from the pre-tank and the outdoor storage.
Accordingly, the emissions for the storage in the pre-tanks are included under the outdoor storage of liquid fraction of the slurry, adjusted by the relative content of C and N in the liquid fraction of the slurry. This will underestimate the emissions from storage. The assumption is discussed under sensitivity analysis.
The energy consumption for stirring in the pre-tank and for pumping slurry from the pre-tank is shown in table C.1.
Table C.1 Energy consumption for stirring and pumping slurry during storage in the pre-tank. All data per 1000 kg of slurry “ex housing”.
| Fattening pig slurry | |
|---|---|
| Electricity for stirring in the pre-tank before pumping. | 1.2 kWh |
| Electricity for pumping from the pre-tank to the outdoor storage. | 0.5 kWh |
| Total | 1.7 kWh |
C.4 Samson Bimatech Mechanical Separation
The mechanical separation is done with a screw press machine and an arc strainer in combination. The manure is first led to the separator. The machine consists basically of a screw and a cylindrical filter around. The screw is slowing rotation forward. At the end of the screw is conical opening partly closed (controlled by air pressure) by a cone. The difficulties for the fibres to leave at the end presses the water fraction in tangential direction through a thin layer of fibres and the steel filter with 3 mm round holes. The thin layer of fibres between the screw and the filter acts as an extra filter and makes it possible to filter very small parts and particles from the manure. The wet fraction is led to a box with two arc strainers and passes first one with and later after lifting with a pump the second. The size of the openings of the two are different (in the range 500 – 1000 µm) with the biggest column first in the flow direction. The extra separated particles are pumped back to the separator and is given a new possibility for ending with the dry fraction.
It is assumed that the composition of the slurry leaving the pre-tank is the same as the “ex housing” composition in the reference scenario, as it has been assumed that there are no loss or emissions during the storage in the pre-tank. The assumption is not strictly correct due to the biological processes in the slurry during the residence time in the stable (a period between one and six weeks) and the pre-tank, however, it has not been possible to identify qualified data on the biological decomposition in the stable and pre-tank.
The efficiency of the mechanical separation is estimated in table C.2
The efficiency of separation is typically measured as the “separation index”. The separation index is the mass of a compound in the solid fraction divided by to the mass of the compound in the original slurry before separation, i.e.
| Separation index for N (%) = | kg N in solid fraction | * 100% |
| kg N in slurry before separation |
The separation index for N can be interpreted as the percentage of the total N in the raw slurry that ends up in the solid fraction.
The separation index has been calculated for the Samson Bimatech separation plant, and this has been compared to literature data for mechanical screw presses. The separation indexes for mechanical separation using screw presses are shown in table C.2 for pig slurry. It should be noted that none of the mass balances are correct, neither in Møller et al. (2000), Møller et al. (2002) or for the data from Samson Bimatech (i.e the N in the solid fraction + N in the liquid fraction does not correspond with N in the slurry before separation). The deviations in the mass balances are shown in table C.2, and it should be noted that the deviations are rather high, which means that the uncertainty on the measured data is significant.
The separation indexes for DM, N, P and K have been used for calculating the composition of the fiber fraction and the liquid fraction for the separation of the “reference slurry” (from Annex A). However, it has to be emphasized that the separation indexes depend to a high degree on the water content of the water and DM. In “real life”, separation of slurry with a high content of DM will lead to more fibre fraction than separation of slurry with a low content of DM. Accordingly, the use of the separation indexes from table C.2 should be seen as “the best possible approximation” which demands some assumptions, as described below.
First it should be emphasized that the reference pig slurry contains less water than real pig slurry. As described in Annex A, the reference pig slurry is based on the Danish Norm Data (Poulsen et al. (2001), DJF (2008a) and DJF (2008b)), and water from the housing units – used for cleaning - is not included in the Norm Data. The amount of water that is not included is probably in the order of 220 litres of water per 1000 kg pig slurry 1.
If these amounts were included, the DM, N, P and K would be 22% lower. Accordingly, the DM content of the slurry would be 5.7% instead of 6.97%, which is far more realistic when comparing with real pig slurry samples.
Table C.2. Separation indexes for mechanical separation of pig slurry.
| Compo- sition of slurry before sepa- ration [kg/1000 kg slurry] |
Fibre fraction/ slurry amount [%] |
Compo- sition of fibre fraction [kg/1000 kg slurry] |
Compo- sition of liquid fraction [kg/1000 kg slurry] |
Mass balance: Amount in fibre fraction and Sepa- ration index [kg] and [%] |
Mass balance: Amount in liquid fraction [kg] |
Total amount in fibre fraction + liquid fraction and deviation in mass balance [kg] |
|
|---|---|---|---|---|---|---|---|
| Total mass | |||||||
| Ref 1 | 4.21% | 42.1 kg | 957.9 kg | ||||
| Ref 2a | 5.0% | 50 kg | 950 kg | ||||
| Ref 2b | 7.3% | 73 kg | 927 kg | ||||
| Samson Bimatech | 3.3% | 33 kg | 967 kg | ||||
| Dry matter (DM) | |||||||
| Ref 1 | 53.2 | 4.21% | 344.4 | 42.5 | 14.5 (27%) | 40.7 | 55.2 (+2) |
| Ref 2a | 56.6 | 5.0% | 317 | 32 | 15.9 (28%) | 30.4 | 46.8 (-9.8) |
| Ref 2b | 56.6 | 7.3% | 219 | 32 | 16.0 (28%) | 29.7 | 45.7 (-10.9) |
| Samson Bimatech | 44.3 | 3.3% | 396.9 | 31.1 | 13.1 (29.6%) | 30.1 | 43.2 (-1.1) |
| Used in this study | 29.6% | ||||||
| Total-N | |||||||
| Ref 1 | 4.20 | 4.21% | 6.61 | 5.00 | 0.28 (6.7%) | 4.79 | 5.07 (+0.87) |
| Ref 2a | 4.1 | 5.0% | 4.8 | 3.0 | 0.24 (5.9%) | 2.85 | 3.09 (-1.01) |
| Ref 2b | 4.1 | 7.3% | 4.0 | 4.2 | 0.29 (7.1%) | 3.89 | 4.18 (+0.08) |
| Samson Bimatech | 4.28 | 3.3% | 8.80 | 4.04 | 0.29 (6.8%) | 3.91 | 4.2 (-0.08) |
| Used in this study | 6.8% | ||||||
| Total-P | |||||||
| Ref 1 | 1.26 | 4.21% | 2.13 | 1.23 | 0.09 (7%) | 1.18 | 1.27 (+0.01) |
| Ref 2a | 1.4 | 5.0% | 3.3 | 0.8 | 0.17 (12%) | 0.76 | 0.93 (-0.47) |
| Ref 2b | 1.4 | 7.3% | 2.9 | 1.0 | 0.21 (15 %) | 0.93 | 1.14 (-0.26) |
| Samson Bimatech | 0.64 | 3.3% | 1.76 | 0.57 | 0.058 (9.1%) | 0.55 | 0.61 (-0.03) |
| Used in this study | 9.1% | ||||||
| Potassium (K) | |||||||
| Ref 1 | No data | No data | No data | No data | No data | No data | |
| Ref 2 | No data | No data | No data | No data | No data | No data | |
| Samson Bimatech | 1.6 | 3.3% | 1.41 | 1.64 | 0.047 (2.9%) | 1.586 | 1.63 (+0.03) |
| Used in this study | 2.9% | ||||||
| Carbon (C) | No data | No data | No data | No data | No data | No data | No data |
| Copper (Cu) | No data | No data | No data | No data | No data | No data | |
| Ref 3 | 6.4% | ||||||
| Used in this study | 6.4% | ||||||
| Zinc (Zn) | No data | No data | No data | No data | No data | No data | |
| Ref 3 | 6.3% | ||||||
| Used in this study | 6.3% |
Ref 1: Møller et al. (2002) – pig slurry, screw press separation
Ref 2a: Møller et al. (2000) – pig slurry, screw press separation, sample no a
Ref 2b: Møller et al. (2000) – pig slurry, screw press separation, sample no b
Ref 3: Møller et al. (2007) – data for the screw press separation
Samson Bimatech: Measurement made on piglet pig slurry 3 February 2009
Due to the lower content of water in the slurry, it has been necessary to adjust the separation index for the total mass of the slurry in order to create a realistic fiber fraction. Accordingly, the liquid fraction from separation of the reference slurry will be “too concentrated” i.e. containing too small amounts of water – like the original reference slurry. It means that one should keep in mind, that the liquid fraction – in real life – probably will contain significantly more water. The composition of the “theoretically calculated Norm Data fiber fraction” has been compared to measurements of separation of piglet slurry (the measurements are made by OK Laboratorium for Jordbrug in Viborg on behalf of Samson Bimatech). Thereby it is ensured that a realistic composition of the fiber fraction has been established. The liquid fraction is then calculated as the difference between the reference slurry and the fiber fraction. This means that the water content of the liquid fraction will be lower than the measurements by Samson Bimatech (due to the relatively low water content of the reference slurry). As the emissions and field processes are calculated in relation to the amount of N and C, the water content (not the concentration) is relatively unimportant for the overall results.
Accordingly, a new theoretical calculation of the mass is needed. As the “Norm Data slurry” contains 69.7 kg DM and the fibre fraction (after separation) contains 396.9 kg DM per 1000 kg fibre fraction, a separation of the “Norm Data fattening pig slurry” will lead to 51.98 kg fibre fraction 2 and 948.02 kg liquid fraction 3.
The calculations for the separation are shown in table C.3.
The calculations in table C.3 are based on a combination of the measured values of the fibre fraction after separation and the separation indexes from table C.2.
The DM is split between the fibre fraction and the liquid fraction in accordance with the separation index in table C.2, i.e. 29.8% of the DM is transferred to the fibre fraction (and the rest to the liquid fraction).
From this, it is calculated that 0.37 kg DM ends in the fibre fraction4.
The slurry content of N is split between the fibre fraction and the liquid fraction in accordance with the separation index in table C.2, i.e. 6.8% of the N is transferred to the fibre fraction (and the rest to the liquid fraction). From this, it is calculated that 0.37 kg N ends in the fibre fraction5. This corresponds to a concentration of 7.17 kg N per 1000 kg fibre fraction 6. The measurements of the fibre fraction from the piglet slurry showed a content of total-N of 8.8 kg N per 1000 kg fibre fraction. The difference is in correspondence with the fact that the Norm Data contains less total N per kg DM (7.9 kg N per kg DM) compared to the measured data for the piglet slurry (9.7 kg N per kg DM). The difference is within the differences that can be found in real life between various slurry samples.
The slurry content of P is split between the fibre fraction and the liquid fraction in accordance with the separation index in table C.2, i.e. 9.1% of the P is transferred to the fibre fraction (and the rest to the liquid fraction). From this, it is calculated that 0.10 kg P ends in the fibre fraction7. This corresponds to a concentration of 1.98 kg P per 1000 kg fibre fraction 8. The measurements of the fibre fraction from the piglet slurry showed a content of phosphorous of 1.76 kg P per 1000 kg fibre fraction. The difference is within the differences that can be found in real life between various slurry samples.
The slurry content of K is split between the fibre fraction and the liquid fraction in accordance with the separation index in table C.2, i.e. 2.9% of the K is transferred to the fibre fraction (and the rest to the liquid fraction). From this, it is calculated that 0.083 kg K ends in the fibre fraction9. This corresponds to a concentration of 1.59 kg K per 1000 kg fibre fraction 10. The measurements of the fibre fraction from the piglet slurry showed a content of phosphorous of 1.41 kg K per 1000 kg fibre fraction. The difference is within the differences that can be found in real life between various slurry samples.
A separation index for Cobber and Zink is taken from Møller et al (2007), see table C.2. These have been used for splitting Cu and Zn between the fibre fraction and the liquid fraction.
The composition of the fibre fraction is used to calculate the composition of the liquid fraction in table C.3. The composition of the liquid fraction is calculated as the difference between the content in the Norm Data slurry minus the content in the fibre fraction. Note that the amount of water is far too low in the liquid fraction, as mentioned above. The liquid fraction would normally contain 2-3% Dry Matter (personally correspondence, J Mertz, 2009).
Table C.3. Mass balances for mechanical separation of slurry from fattening pigs.
Per 1000 kg of slurry “ex housing”.
| Amount in slurry Ex pre-tank BEFORE separation |
Separation index from table C.2 | Mass Balance: Amount transferred to the fibre fraction |
Mass balance: Amont transferred to the liquid fraction | Composition of the fiber fraction AFTER separation |
Composition of liquid fraction b) AFTER separation |
|
|---|---|---|---|---|---|---|
| i.e. “ex housing values from table A.1 in Annex A | Fibre fraction * 1000 / 51.98 kg | Liquid fraction * 1000 kg / 948 kg | ||||
| [per 1000 kg ex pre-tank] | [per 1000 kg ex pre-tank] | [per 1000 kg ex pre-tank] | [kg per 1000 kg fiber fraction] | [kg per 1000 kg liquid fraction] | ||
| Total mass | 1000 kg Slurry Ex pre-tank |
Not used a) | 51.98 kg b) | 1000 kg – 51.98 kg = 948.02 kg |
1000 kg Fibre fraction |
1000 kg liquid fraction |
| Dry matter (DM) | 69.7 kg | 29.6% | 69.7 kg *29.6% = 20.63 kg |
69.7 kg *(100-29.6)% = 49.07 kg |
396.9 kg | 51.76 kg |
| Total-N | 5.48 kg | 6.8% | 5.48 kg *6.8% = 0.3726 kg |
5.48 kg *(100-6.8)% = 5.1074 kg |
7.17 kg | 5.387 kg |
| Total-P | 1.13 kg | 9.1% | 1.13 kg *9.1% = 0.102 kg |
1.13 kg *(100-9.1)% = 1.027 kg |
1.962 kg | 1.0833 kg |
| Potassium (K) | 2.85 kg | 2.9% | 2.85 kg *2.9% =0.08265 kg |
2.85 kg *(100-2.9)% = 2.767 kg |
1.59 kg | 2.9187 kg |
| Carbon (C) | 33.3 kg | No data Assumed: 29.6% |
33.3 kg *29.6% = 9.859 kg |
33.3 kg *(100-29.6)% = 23.443 kg |
189.67 kg | 24.728 kg |
| Copper (Cu) | 30.0 g | 4.6% | 30.0 g *4.6% = 1.38 g |
30.0 g *(100-4.6)% = 28.62 g |
26.549 g | 30.189 g |
| Zinc (Zn) | 89.4 g | 6.3% | 89.4 g *6.3% = 5.632 g |
89.4 g *(100-6.3)% = 83.768 g |
108.35 g | 88.361 g |
| Water content | 1000 kg - 69.7 kg = 930.3 kg |
31.35 kg c) | 898.95 kg |
- The separation index for the mass (3.3%) from table C.2 has not been used as it gave unrealistic results for both the fibre fraction and the liquid fraction.
- The calculation of the total mass is based on measurement of the fibre fraction, which has a DM of 39.69%. When the DM is 39.69%, and the total DM is 20.63 kg, the total mass is 20.63 kg * 100/39.69 = 51.98 kg
- Total mass-DM = 51.98 kg – 20.63 kg = 31.35 kg
In table C.4 the life cycle inventory data for mechanical separation can be seen. It has not been possible to identify data on emissions from the process. It is assumed that the emissions from the storage of the fiber fraction after the separation process exceeds the emissions during the separation process itself. The lack of data is especially critically for emissions of ammonia, which is supposed to be emitted in significant amounts. It is roughly estimated that the amount of ammonia, that is emitted during separation would be emitted anyway during storage at a later point. Sensitivity analysis for this assumption has been carried out.
Focus has been put on the attempt to find data on storage of the fiber fraction, see the next section.
The energy consumption for the mechanical separation is 0.95 kWh per 1000 kg pig slurry (Mertz, 2008). Møller et al. (2002) found an energy consumption for screw press separation at 0.90 kWh per 1000 kg pig slurry (and 1.1 kWh per 1000 kg cattle slurry), which is well in accordance with the data from Samson Bimatech. Møller et al. (2000) found an energy consumption of 0.53 kWh per 1000 kg cattle slurry for a “pressing screw separator” which is regarded as within the uncertainty range of the data.
Table C.4. Life cycle data for mechanical separation (Samson Bimatech). Data per 1000 kg slurry (ex pre-tank).
| Fattening pig slurry | Comments | |
|---|---|---|
| Input | ||
| Slurry (ex pre-tank) | 1000 kg | Slurry directly from the pre-tank under the pig housing units. This is the reference amount of slurry, i.e. the emissions are calculated relative to this. |
| Output | ||
| Fibre fraction | 52 kg | |
| Liquid fraction | 948 kg | Reject slurry / liquid phase of the slurry |
| Energy consumption | ||
| Electricity | 0.95 kWh | Reference: Personal communication, J. Mertz, 2008. |
| Emissions to air | ||
| Carbon dioxide (CO2) | No data | |
| Methane (CH4) | No data | |
| Non-methane volatile organic compounds (NMVOC) | No data | |
| Ammonia (NH3-N) | No data. Sensitivity analysis carried out for this. | |
| Nitrous oxide (N2O-N) | No data | |
| Nitrogen oxides (NOX) | No data | |
| Nitrogen monoxide(NO) | No data | |
| Nitrogen(N2) | No data | |
| Particulates | No data | |
| Hydrogen sulphide (H2S) | No data | |
| Sulphur dioxide (SO2) | No data | |
| Odour | No data | |
| Emissions to water | ||
| No emissions to water |
A list of the materials used in for the construction of the mechanical separation plant is shown in table C.5. The consumption is based on qualified expert estimates.
Table C.5 Material consumption and for the mechanical separation plant.
| Materials | Weight of material in plant |
Estimated life time |
Amount of slurry per year [m³ slurry per year] |
Amount of slurry in a life time [m³ slurry in a life time] |
Weight [per 1000 kg slurry] |
|---|---|---|---|---|---|
| Separation Plant ¹) | |||||
| Steel in container | 2 300 kg | 30 years | 15000 m³ / y | 450000 m³ | 5 g |
| Steel in compressor | 2 700 kg | 30 years | 15000 m³ / y | 450000 m³ | 6 g |
| Copper in cables | 10.5 kg | 30 years | 15000 m³ / y | 450000 m³ | 0.023 g |
| Electronics | 0.5 kg -Assumed as 0.5 laptops | Assumption: 5 years |
15000 m³ / y | 75000 m³ | 6.67 E-6 laptops |
| Screw in screw press ²)Steel | 50 kg | 1 years | 15000 m³ / y | 15000 m³ | 3.3 g |
| Filter for screw press ³)Steel | 6.5 kg | 0.5 year | 15000 m³ / y | 7500 m³ | 0.86 g |
The density of slurry roughly 1000 kg per m³ used for these estimates (as it is rough estimates anyway).
C.5 Outdoor storage of the liquid fraction
The outdoor storage of the liquid fraction is assumed to be identical to the outdoor storage of the untreated slurry in Annex A, adjusted by the relative ratio of N and C in the liquid fraction compared to the untreated slurry in Annex A. For a description of the assumptions and references, see Annex A.
This process included the energy consumptions for:
- Stirring slurry in the outdoor concrete tank when straw is added (pig slurry only)
- Stirring slurry before pumping from outdoor storage tank.
- Pumping slurry from the storage tank to the transport tank.
The energy consumptions are shown in table C.6. See further description in Annex A.
Table C.6 Energy consumption for stirring and pumping slurry during storage. All data per 1000 kg of slurry “ex housing”.
| Fattening pig slurry | |
|---|---|
| Electricity for stirring in the outdoor concrete tank when straw is added (pig slurry only) | 1.2 kWh |
| Electricity for stirring in the outdoor concrete tank before pumping to transport container. | 1.2 kWh |
| Electricity for pumping from the storage tank to the transport container. | 0.5 kWh |
| Total | 2.9 kWh |
Table C.7 Life cycle data for storage of the liquid fraction. All data per 1000 kg of liquid fraction “ex separation”.
| Reference pig slurry (scenario A) |
Liquid fraction from fattening pigs (scenario C) |
Comments | |
|---|---|---|---|
| Input | |||
| Slurry “ex separation” | 1000 kg | The emissions are calculated relative to this. | |
| Concrete slurry store | Included | As in scenario A. | |
| Output | |||
| Slurry “ex storage” | 1086 kg | As mass balance from scenario A. | |
| Energy consumption | |||
| Not included here | No energy consumption. Energy consumption for pumping and stirring is included under the process “Pumping and stirring” | ||
| Emissions to air | |||
| Carbon dioxide (CO2) | 0.18 kg | 0.13 kg | Scenario A: 0.18 kg 0.18 kg * 24.7 kg (C in liquid fraction) / 33.3 kg (C in ex housing slurry in scenario A) = 0.13 kg |
| Methane (CH4) | 1.94 kg | 1.44 kg | Scenario A: 1.94 kg 1.94 kg * 24.7 kg (C in liquid fraction) / 33.3 kg (C in ex housing slurry in scenario A) = 1.44 kg |
| Ammonia (NH3-N) | 0.11 kg | 0.11 kg | The total-N in the reference slurry ex housing is 5.48 kg per 1000 kg slurry. The total-N in the liquid fraction ex separation is 5.39 kg per 1000 kg liquid fraction. The difference of the N content in the reference slurry “ex housing” from scenario A and the N content in the liquid fraction is less than 2%. Accordingly, the emissions are assumed to be identical for the two scenarios. |
| Direct emissions of Nitrous oxide (N2O-N) | 0.033 kg | 0.033 kg | |
| Indirect emissions of Nitrous oxide (N2O-N) |
0.0014 kg | 0.0014 kg | |
| Nitrogen monoxide (NO-N) (representing total NOX) | 0.033 kg | 0.033 kg | |
| Nitrogen dioxide (NO2-N) | No data | No data | |
| Nitrogen (N2-N) | 0.099 kg | 0.099 kg | |
| Discharges to water | |||
| None | Assumed to be none, as leakages from slurry tanks are prohibited in Denmark |
The composition of the liquid fraction after storage is shown in table C.8.
Note that the amount of water is far too low in the liquid fraction, as mentioned above.
Table C.8. Mass balances for storage of the liquid fraction after mechanical separation of slurry from fattening pigs.
| Composition of liquid fraction before storage (from table C.2) |
Mass balance: Change during storage |
Mass balance: Amount after storage |
Composition of liquid fraction after storage a) |
|
|---|---|---|---|---|
| [kg per 1000 kg liquid fraction] |
[kg] | [kg] | [kg per 1000 kg liquid fraction] |
|
| Total mass | 1000 kg liquid fraction BEFORE storage |
+ 86 kg (as in Annex A) | 1086 kg | 1000 kg liquid fraction after storage |
| Dry matter (DM) | 51.76 kg | - 1.864 kg d) | 49.9 kg | 45.9 kg |
| Total-N | 5.387 kg | - 0.275 kg b) | 5.11 kg | 4.71 kg |
| Total-P | 1.0833 kg | None | 1.09 kg | 1.00 kg |
| Potassium (K) | 2.9187 kg | None | 2.92 kg | 2.69 kg |
| Carbon (C) | 24.728 kg | -1.114 kg c) | 23.6 kg | 21.745 kg |
| Copper (Cu) | 30.189 g | None | 30.189 g | 0.0278 kg |
| Zinc (Zn) | 88.361 g | None | 88.361 g | 0.08136 kg |
- Calculated by dividing with the mass of the liquid fraction i.e. 1000 kg / 1086 kg
- Emissions: 0.11 kg NH3-N + 0.033 kg kg N2O-N + 0.033 kg NO + 0.099 kg N2 = 0.275 kg
- Emissions: 0.13 kg CO2 * 12.011 / 44.0089 + 1.44 kg CH4 * 12.011 / 16.04 = 1.114 kg C
- Assumption for DM: 80% is VS, the loss of VS corresponds to the relative loss of C, i.e. 1.114 kg C/24.728 kg C = 4.5%. Loss = 51.8 kg * 80% * 4.5% = 1.864 kg
C.6 Transport of the liquid fraction to field
The transport of the liquid fraction to field is assumed to be identical to the transport of the untreated slurry in Annex A.
C.7 Field processes (liquid fraction)
The emissions from the field processes are calculated relative to the emissions from the reference slurry in scenario A. The life cycle data for the field processes are shown in table C.9.
In order to calculate N leaching values, the simplifying assumption that the liquid fraction, once the respective ammonia losses have been subtracted, can be equaled by a predominant proportion of slurry, and a smaller amount of mineral N, as in mineral fertiliser as the liquid fraction has a higher content of N relative to C, than the original reference slurry (as the mechanical separation separates relatively more C to the fibre fraction (i.e. 29.6%) than N (6.8%). As the amount of organic matter is one of the key properties for its effect on the N partitioning, the amount of C relative to N in the pig slurry from the basis scenario is used. The N values are taken after ammonia volatilization. The C:N proportion is 29.2 [kg C] / (4.80-0.02-0.48) [kg N] = 6.79 for the slurry and 21.7 [kg C] / (4.71-0.02-0.24) [kg N] = 4.876 for the liquid fraction. The “virtual” proportion of N assumed to affect the soil and plants as pig slurry is therefore 4.876/6.79 = 0.72, and the virtual proportion of N assumed to affect the soil and plants as mineral N is accordingly 0.28. The tables A.14 and A.15 are therefore the basis for the calculation of N leaching, after correcting for their respective ammonia volatilizations.
According to Hansen et al. (2008), the ammonia volatilization from the liquid fraction from separated slurry applied to fields is reduced significantly – in the order of 50%. The explanation given by Hansen et al. (2008) is that the dry matter in the liquid fraction is normally less than 3% which means that the liquid fraction infiltrates very fast in the soil. Hence, the volatilization of ammonia from the applied liquid fraction stops faster than for untreated slurry. Measurements were made on mechanically separated slurry (untreated and degassed slurry), and the liquid fraction / slurry were applied by trail hoses. The measurements showed that the ammonia emissions were reduced by approximately 50% (Hansen et al., 2008).
As discussed above, the liquid fraction from mechanically separation of the reference slurry in this study has a DM content that is unrealistic high due to too small amounts of water in the Danish Norm Data for slurry. However, for a realistic scenario, the liquid fraction from the mechanically separation would have a DM content of less than 3%, as presumed in Hansen et al. (2008). Measurements from the Samson Bimatech plant show that the liquid fraction contains 2-3.5% DM after separation (Personal communication, J Mertz, 2008). It means: In spite of the theoretical calculations for mechanical separation of the “Danish Norm Data slurry”, it has been assumed that the experience by Hansen et al. (2008) also applies for the reference slurry, as it has been acknowledged that there should have been a higher water content – and hence, that the DM content should have been lower. Accordingly, it is assumed that the ammonia emissions are reduced by 50% as indicated by Hansen et al. (2008). It is assumed that it applies for ammonia emissions in period after application only, i.e. not for the ammonia emissions during application – due to the explanation above.
Table C.9. Life cycle data for application of the liquid fraction and field processes (scenario C). All data per 1000 kg of slurry, resp. liquid fraction ex outdoor storage.
| Reference pig slurry (scenario A) |
Liquid fraction from fattening pigs (scenario C) |
Comments | |
|---|---|---|---|
| Input | |||
| Slurry “ex storage” | 1000 kg | 1000 kg | Slurry from the outdoor storage. This is the reference amount of slurry, i.e. the emissions are calculated relative to this. |
| Output | |||
| Slurry on field, fertiliser value |
Fertiliser replacement value: See Annex A |
Fertiliser replacement value: See Annex D and E |
The fertiliser value of this slurry results in subtraction of mineral N, P and K N fertiliser value – Depends on the utilisation of the fibre fraction. See the subsequent Annexes. |
| Energy consumption | |||
| Diesel for slurry | 0.4 litres of diesel | 0.4 litres of diesel | As in scenario A. |
| Emissions to air | |||
| Carbon dioxide (CO2) Soil JB3 Soil JB6 |
81.6 (99.8) kg 80.2 (99.4) kg |
56.2 (73.562) kg 55.1 (73.142) kg |
Modelled by C-TOOL (Gyldenkærne et al, 2007). 10 year value and 100 year in parenthesis |
| Methane (CH4) | Negligible | Negligible | As in scenario A. |
| Ammonia (NH3-N) during application |
0.02 kg | 0.02 kg | NH3 emissions during application: 0.5% of NH4+-N “ex storage” Hansen et al. (2008). N ex storage = 4.71 kg |
| Ammonia (NH3-N) in period after application |
0.48 kg | 0.24 kg | NH3 emissions in the period after application are based on Hansen et al. (2008) and the current slurry distribution in the crop rotation, see Annex A. 50% of this for liquid fraction, see above (Hansen et al., 2008). |
| Direct emissions of Nitrous oxide (N2O-N) |
0.05 kg [0.015-0.15] |
0.05 kg [0.015-0.15] |
0.01 [0.003 - 0.03] kg N2O-N per kg N “ex storage” for application of animal wastes to soil, based on IPPC (2006, table 11.1). |
| Indirect emissions of Nitrous oxide (N2O-N) Soil JB3 Soil JB6 |
0.005 kg 0.014 kg 0.011 kg |
0.005 kg 0.014 kg 0.011 kg |
Indirect emissions due to emissions of ammonia and NOX: 0.01 kg N2O–N per kg (NH3–N + NOX–N) volatilised (IPCC, 2006) Indirect emissions due to nitrate leaching: 0.0075 kg N2O–N per kg N leaching (IPCC, 2006). |
| Nitrogen oxides (NOx-N) | 0.005 kg | 0.005 kg | NOX–N = 0.1 * N2O-N according to Nemecek and Kägi (2007) |
| Nitrogen (N2-N) Soil JB3 Soil JB6 |
0.15 kg 0.30 kg |
0.15 kg 0.30 kg |
Estimated from the SimDen model ratios between N2O and N2 by Vinther (2005), see text. |
| Discharges to soil | |||
| Nitrate leaching Soil JB3 Soil JB6 |
1.91 (2.12) kg N 1.50 (1.67) kg N |
1.95 (2.17) kg N 1.53 (1.70) kg N |
Estimated from N partitioning tables A.15 and A.16 as explained in text. 10 year values, numbers in parenthesis are 100 year values. |
| Phosphate leaching | 0.113 kg P | 0.10 kg P | 10% of the P applied to field (Hauschild and Potting, 2005 – only 6% of this reach the aquatic environment, see text). |
| Copper (Cu) | 0.0276 kg | 0.027 kg | See table A.18 and C.8 |
| Zinc (Zn) | 0.0824 kg | 0.0856 kg | See table A.18 and C.8 |
C.8 Avoided mineral fertilisers
The calculation of the fertiliser replacement value for N in the liquid fraction depends on the utilization of the fibre fraction. If, for example, the fibre fraction is combusted, the amount of N in the liquid fraction of the slurry replace mineral N fertiliser by 85% according to Danish Law (Gødskningsbekendtgørelsen, 2008, and Gødskningsloven, 2006) as described in Annex D.
Accordingly, the fertiliser replacement value for the liquid fraction is calculated in each of the subsequent Annexes (D and E).
[1] The exact amount is not known. From table A.4 in Annex A, an estimate based on data from Poulsen et al. (2001) indicates that water added in the housing units corresponds to approximately 223 litres per 1000 slurry. Poulsen et al. (2001) do not include this amount.
[2] The Norm Data slurry contains 69.7 kg DM. 29.6% of the DM ends up in the fibre fraction (see table C.2) i.e. 69.7 kg * 29.6% = 20.63 kg DM. As the fibre fraction contains 396.9 kg DM per 1000 kg fibre fraction (due to measurements), the total amount of fibre fraction is: 20.63 kg DM / (396.9 kg DM per 1000 kg fibre fraction) = 51.98 kg fibre fraction.
[3] 1000 kg slurry – 51.98 kg fibre fraction = 948.02 kg liquid fraction.
[4] The Norm Data Slurry contains 69.7 kg DM ex housing. 29.6% of this ends in the fibre fraction according to the separation index in table C.2.
69.7 kg DM * 6.8% = 0.373 kg N.
[5] The Norm Data Slurry contains 5.48 kg N ex housing. 6.8% of this ends in the fibre fraction according to the separation index in table C.2.
5.48 kg N * 6.8% = 0.373 kg N.
[6] 0.373 kg N / 51.98 kg fibre fraction * 1000 kg = 7.17 kg N per 1000 kg fibre fraction.
[7] The Norm Data Slurry contains 1.13 kg P ex housing. 9.1% of this ends in the fibre fraction according to the separation index in table C.2.
1.13 kg P * 9.1% = 0.10283 kg P.
[8] 0.10283 kg P / 51.98 kg fibre fraction * 1000 kg = 1.97826 kg P per 1000 kg fibre fraction.
[9] The Norm Data Slurry contains 2.85 kg K ex housing. 2.9% of this ends in the fibre fraction according to the separation index in table C.2.
2.85 kg K * 2.9% = 0.083 kg K.
[10] 0.083 kg K / 51.98 kg fibre fraction * 1000 kg = 1.59 kg K per 1000 kg fibre fraction.
Version 1.0 July 2009, © Danish Environmental Protection Agency