Carbon Footprint of Food Waste Management: A Case …
43
(continued)
P C H4 (methane produced)
Calculated
t (period of time)
Calculated
x (current time)
Considered to be zero, as the present time
R(t) (methane recovery, Gg.year −1 )
1.0 (based on CETESB, 2010)
O X (oxidation factor, dimensionless):
0.1 [7]
M FC (methane correction factor,
dimensionless):
0.6 [24]
DOC (degradable organic carbon,
dimensionless):
0.85 [10]
DOC F (fraction of DOC dissimilated,
dimensionless):
0.5 [24]
F (fraction of methane in landfill gas,
dimensionless):
0.5 [7]
molecular weight (CH 4 /C):
16/12 = 1.33 [24]
So, first of all, the methane production was calculated based on Eqs. (1), (2) and
(3) for a period of one year and then the total methane emissions were calculated
discounting the amount of recovered methane, as shown in Eq. (4).
E C H4 =
(1 − O X) × (P C H4 − R C H4 )
d C H4
(4)
where:
E C H4 (total of methane emissions, m 3 ·year −1 )
Calculated
O X(oxidation factor, dimensionless):
0.1 [7]
P C H4 (methane produced)
Calculated
R C H4 (total of methane recovery, Gg·year −1 )
1 (based on [7])
d C H4 (methane density, Gg·m −3 )
0.000000657
So, the estimated data of total methane emissions produced in one day was inserted
in Excel spreadsheet [15], together with total methane recovery, for direct emissions
from biogas combustion unit. Moreover, the emissions from permanent combustion
facilities and on-site equipment is based on Angelo [2] for diesel consumption,
estimated in volume.
Finally, for “Anaerobic Digestion” direct emissions calculation, in case of alternative scenario, the input variables were: quantity of food waste treated (tons), biogas
yield, percentage of biogas leakage from bioreactor and its methane content, volume
of biogas treated in combustion unit and its methane content and diesel fuel consumption of other on-site equipment. The electricity consumption is accounted for indirect
emissions. Data from the garage-type SSAD plant [10], located at the EcoParqueCaju, Rio de Janeiro, are considered for this calculation. Table 2 summarizes the
values for all these variables.
43
(continued)
P C H4 (methane produced)
Calculated
t (period of time)
Calculated
x (current time)
Considered to be zero, as the present time
R(t) (methane recovery, Gg.year −1 )
1.0 (based on CETESB, 2010)
O X (oxidation factor, dimensionless):
0.1 [7]
M FC (methane correction factor,
dimensionless):
0.6 [24]
DOC (degradable organic carbon,
dimensionless):
0.85 [10]
DOC F (fraction of DOC dissimilated,
dimensionless):
0.5 [24]
F (fraction of methane in landfill gas,
dimensionless):
0.5 [7]
molecular weight (CH 4 /C):
16/12 = 1.33 [24]
So, first of all, the methane production was calculated based on Eqs. (1), (2) and
(3) for a period of one year and then the total methane emissions were calculated
discounting the amount of recovered methane, as shown in Eq. (4).
E C H4 =
(1 − O X) × (P C H4 − R C H4 )
d C H4
(4)
where:
E C H4 (total of methane emissions, m 3 ·year −1 )
Calculated
O X(oxidation factor, dimensionless):
0.1 [7]
P C H4 (methane produced)
Calculated
R C H4 (total of methane recovery, Gg·year −1 )
1 (based on [7])
d C H4 (methane density, Gg·m −3 )
0.000000657
So, the estimated data of total methane emissions produced in one day was inserted
in Excel spreadsheet [15], together with total methane recovery, for direct emissions
from biogas combustion unit. Moreover, the emissions from permanent combustion
facilities and on-site equipment is based on Angelo [2] for diesel consumption,
estimated in volume.
Finally, for “Anaerobic Digestion” direct emissions calculation, in case of alternative scenario, the input variables were: quantity of food waste treated (tons), biogas
yield, percentage of biogas leakage from bioreactor and its methane content, volume
of biogas treated in combustion unit and its methane content and diesel fuel consumption of other on-site equipment. The electricity consumption is accounted for indirect
emissions. Data from the garage-type SSAD plant [10], located at the EcoParqueCaju, Rio de Janeiro, are considered for this calculation. Table 2 summarizes the
values for all these variables.