284
in 2012. Coproducts were taken into account by the “substitution by system expansion” or “avoided burden method” considering the average primary route market
consumption mix. The “zero burden assumption” was also used, which means that
it was considered that the waste carries none of the upstream burdens into the waste
management system (Clift et al. 2000 ).
For modeling purposes, the various activities were organized as groups of associated processes, as follows: (1) waste generation, (2) collection of sorted MSW
(material and biodegradable waste); (3) collection of unsorted MSW; (4) organic
recovery; (5) sorting at MRF; (6) mechanical treatment; (7) mechanical-biological
treatment; (8) energy recovery; (9) recycling; (10) landfi ll. The secondary wastes
from waste treatment, as also the materials and energy recovery processes, were
also taken into account.
The detailed analysis of the most important foreground processes constitutes the
backbone of the life cycle inventory and was based on primary data obtained from
the companies that handle the waste (e.g. SPV) and on secondary data from LCA
databases and scientifi c bibliography which were adapted to better refl ect the
Portuguese reality.
The results obtained show that for 7 of the 11 environmental impact categories
considered in the study, the reference MSW system confi guration leads to a positive
or neutral environmental balance. In these cases, the benefi ts due to the recovery of
materials and energy obtained by waste recovery processes (avoided impacts), with
special focus on recycling, are bigger or at least equal to the negative impacts generated by the various waste management activities, like collection, sorting, transport, treatment and recovery. In the remaining four impact categories, the benefi ts
obtained from waste recovery are not suffi cient to mitigate the impacts generated
by its management activities. This is due mainly to a still signifi cant MSW fraction
that is not recovered and is mostly eliminated in landfi lls (in 2012, 5 4 % of the
Portuguese MSW was directly put in landfi ll). This is the case, for example, in the
climate change category, where it was estimated that the net GHG emissions
reached 1.1 Mt CO 2 eq in 2012, equivalent to 1.6 % of the annual GHG emissions in
Portugal.
Comparing the MSW management as a whole with the specifi c management of
packaging materials, it was found that, on a unit basis, the environmental balance of
the packaging materials is more favorable than the remaining fractions. This is due
in part to the intrinsic characteristics of packaging materials, but also to higher recycling rates achieved and the consequently lower amount sent to landfi ll, particularly
for glass, paper/cardboard and ferrous metals.
Comparing the 2012 performance with the target for the year 2020 with the strategy defi ned in PERSU 2020, the results show that the proposed changes will lead to
a major qualitative leap in the environmental performance of the sector. For example,
it is estimated that the net GHG emissions will be reduced by 47 %, which translates
into a emission savings of 522 kt CO2 eq and that the benefi ts obtained from the
recovery of mineral resources, both fossil and renewable, will increase by 61 %
compared to 2012. These benefi ts are due not only to reduction of the quantity sent
to landfi ll, especially the biodegradable fractions, but also to the expected increase
P. Ferrão et al.
in 2012. Coproducts were taken into account by the “substitution by system expansion” or “avoided burden method” considering the average primary route market
consumption mix. The “zero burden assumption” was also used, which means that
it was considered that the waste carries none of the upstream burdens into the waste
management system (Clift et al. 2000 ).
For modeling purposes, the various activities were organized as groups of associated processes, as follows: (1) waste generation, (2) collection of sorted MSW
(material and biodegradable waste); (3) collection of unsorted MSW; (4) organic
recovery; (5) sorting at MRF; (6) mechanical treatment; (7) mechanical-biological
treatment; (8) energy recovery; (9) recycling; (10) landfi ll. The secondary wastes
from waste treatment, as also the materials and energy recovery processes, were
also taken into account.
The detailed analysis of the most important foreground processes constitutes the
backbone of the life cycle inventory and was based on primary data obtained from
the companies that handle the waste (e.g. SPV) and on secondary data from LCA
databases and scientifi c bibliography which were adapted to better refl ect the
Portuguese reality.
The results obtained show that for 7 of the 11 environmental impact categories
considered in the study, the reference MSW system confi guration leads to a positive
or neutral environmental balance. In these cases, the benefi ts due to the recovery of
materials and energy obtained by waste recovery processes (avoided impacts), with
special focus on recycling, are bigger or at least equal to the negative impacts generated by the various waste management activities, like collection, sorting, transport, treatment and recovery. In the remaining four impact categories, the benefi ts
obtained from waste recovery are not suffi cient to mitigate the impacts generated
by its management activities. This is due mainly to a still signifi cant MSW fraction
that is not recovered and is mostly eliminated in landfi lls (in 2012, 5 4 % of the
Portuguese MSW was directly put in landfi ll). This is the case, for example, in the
climate change category, where it was estimated that the net GHG emissions
reached 1.1 Mt CO 2 eq in 2012, equivalent to 1.6 % of the annual GHG emissions in
Portugal.
Comparing the MSW management as a whole with the specifi c management of
packaging materials, it was found that, on a unit basis, the environmental balance of
the packaging materials is more favorable than the remaining fractions. This is due
in part to the intrinsic characteristics of packaging materials, but also to higher recycling rates achieved and the consequently lower amount sent to landfi ll, particularly
for glass, paper/cardboard and ferrous metals.
Comparing the 2012 performance with the target for the year 2020 with the strategy defi ned in PERSU 2020, the results show that the proposed changes will lead to
a major qualitative leap in the environmental performance of the sector. For example,
it is estimated that the net GHG emissions will be reduced by 47 %, which translates
into a emission savings of 522 kt CO2 eq and that the benefi ts obtained from the
recovery of mineral resources, both fossil and renewable, will increase by 61 %
compared to 2012. These benefi ts are due not only to reduction of the quantity sent
to landfi ll, especially the biodegradable fractions, but also to the expected increase
P. Ferrão et al.