42
L. S. Franca et al.
It is important to highlight that, for the current scenario, the food waste mass is
considered to be collected, transported and transferred to the landfill in an aggregate
way, with the inert waste mass also. On the other hand, for the alternative scenario, a
selective collection is considered for the food waste from supermarkets, street fairs
and wholesalers, where the food waste is no longer collected together with the mixed
waste, but in a selective way. In addition, for the alternative scenario, even though
the food waste is separately collected, it was considered a percentage of 15% of
improper materials [10] which has low biodegradable for the SSAD treatment. So,
the improper materials mass was considered to be transfer until the final disposal
at the municipal landfill. However, because of the insignificant biodegradability of
these materials, there is no need for quantifying the GHG emissions at the landfill.
On the other hand, for “Sorting – Transfer” activity, the direct GHG emissions
from permanent facilities and on-site mobile equipment are calculated based on
fuels consumption, which was measured in volume. The amount of diesel which
is consumed is estimated according to Angelo [2]. For indirect emissions from
electricity use, data are also based on Angelo [2].
In case of the GHG emissions from “Landfilling”, this work considers the
IPCC (Tier 2) First order decay model [24] and also some characteristics pointed
out by CETESB [7] for specific variables of the Brazilian reality, the fraction of
methane in landfill gas, methane generation rate constant and biogas oxidation rate.
Equations (1), (2) and (3) describes more specifically this calculation.
P C H4 =
x
(A × k × F W t (x) × F W F (x) × Lo(x)) × e
−k×(t−x)
− R(t)
× (1 − O X)
(1)
Lo = M FC × DOC × DOC F × F × 16/12
(2)
A = (1 − e
−k
)/k
(3)
where
P C H4 (methane produced)
Calculated
A (normalization factor, dimensionless)
Calculated (based on EPE, 2013)
k (methane generation rate constant,
years −1 )
0.09 [7]
F W t (total of food waste produced,
Gg.year −1 )
Sum of food waste produced by the case study
F W F (fraction of total food waste
disposed in landfill)
1.0, for current scenario
Lo(x) (potential of methane emission,
Gg.Gg FW −1 )
Calculated
(continued)
L. S. Franca et al.
It is important to highlight that, for the current scenario, the food waste mass is
considered to be collected, transported and transferred to the landfill in an aggregate
way, with the inert waste mass also. On the other hand, for the alternative scenario, a
selective collection is considered for the food waste from supermarkets, street fairs
and wholesalers, where the food waste is no longer collected together with the mixed
waste, but in a selective way. In addition, for the alternative scenario, even though
the food waste is separately collected, it was considered a percentage of 15% of
improper materials [10] which has low biodegradable for the SSAD treatment. So,
the improper materials mass was considered to be transfer until the final disposal
at the municipal landfill. However, because of the insignificant biodegradability of
these materials, there is no need for quantifying the GHG emissions at the landfill.
On the other hand, for “Sorting – Transfer” activity, the direct GHG emissions
from permanent facilities and on-site mobile equipment are calculated based on
fuels consumption, which was measured in volume. The amount of diesel which
is consumed is estimated according to Angelo [2]. For indirect emissions from
electricity use, data are also based on Angelo [2].
In case of the GHG emissions from “Landfilling”, this work considers the
IPCC (Tier 2) First order decay model [24] and also some characteristics pointed
out by CETESB [7] for specific variables of the Brazilian reality, the fraction of
methane in landfill gas, methane generation rate constant and biogas oxidation rate.
Equations (1), (2) and (3) describes more specifically this calculation.
P C H4 =
x
(A × k × F W t (x) × F W F (x) × Lo(x)) × e
−k×(t−x)
− R(t)
× (1 − O X)
(1)
Lo = M FC × DOC × DOC F × F × 16/12
(2)
A = (1 − e
−k
)/k
(3)
where
P C H4 (methane produced)
Calculated
A (normalization factor, dimensionless)
Calculated (based on EPE, 2013)
k (methane generation rate constant,
years −1 )
0.09 [7]
F W t (total of food waste produced,
Gg.year −1 )
Sum of food waste produced by the case study
F W F (fraction of total food waste
disposed in landfill)
1.0, for current scenario
Lo(x) (potential of methane emission,
Gg.Gg FW −1 )
Calculated
(continued)