Microsoft Word - Environmental benefits of recycling 2010 update.doc

The results highlight large differences between the different cases. This is partly due to the fact that the studies
do not all include the same steps. As mentioned previously, some studies only focus on the end-of-life stage while
others include the whole life cycle without giving the details of the various steps. In addition, some system
boundary issues and key assumptions also have considerable influence on the results discussed below.

Climate change

Figure 25 illustrates that recycling and anaerobic digestion are more favourable than composting regarding
climate change. However it should be noted that the number of cases is limited for these end-of-life alternatives:
five cases for recycling and three for anaerobic digestion.

The picture is less clear regarding composting vs. landfill and incineration since the results differ between the
various studies (see Table 48). This seems to be mainly due to the assumptions chosen regarding the
degradation rate:

 Composting performs better than incineration for the cases assuming a low degradation rate of 30 or

50%

 Incineration performs better than composting for the cases assuming a degradation rate above 90%

The comparison between the results from cases 4[MUB1] and 4[MUB2] for composting vs. landfill illustrates the
influence of the degradation rate. Although placed on the same line on the graph, composting presents an
environmental improvement of 600% for a degradation rate of 30% and of 1700% for a degradation of 50%.

Figure 26 shows that recycling is the most favourable option even versus incineration with energy recovery in 2
cases out of three. When comparing landfill and incineration with energy recovery, it is interesting to notice that
landfill tends to perform better. This can be due to:

 the valorisation of the biogas produced (cases 2[MB] and 2[BIO])

 the choice of a low degradation rate (cases 1[MB]; 1[OCT], 5[PLA]).

In addition, it can be observed from Table 48 and Table 49 that the different Mater-Bi cases do not lead to the
same conclusions. For cases from study no 2, composting appears better than incineration with energy recovery
because the compost produced avoids the production of inorganic fertilisers. On the contrary in study no 1 the
compost produced is not assumed to replace fertilisers and thus composting does not appear as a better
alternative than incineration.

Table 48 Relative difference between the impacts from the different end-of-life options vs. composting for climate change for biopolymers. A
positive value means that composting is preferable to the other end-of-life option. A negative value means that composting causes more
environmental impact than the other end-of-life option.

N° case 1[MB] 1[OCT] 2[PLA] 2[MB] 2[BIO] 3[PLA1]^1 3[PLA2]^2 4[MUB1]4[MUB2] 6[PLA] 6[CE] 7[MAS]^1

Recycling ‐9270% ‐20% ‐40% ‐50%

Incineration with energy recovery ‐10% ‐20% 60% 2060% 2090% ‐60% ‐60% ‐60%

Incineration without energy recovery 110% 110%

Landfill ‐40% ‐50% 60% ‐650% ‐10% 590% 1720%

Anaerobic digestion ‐20% ‐60%

Study n°5 does not include a comparison with composting for this indicator and thus is not included in this table

Composting versus other alternatives

1 21

1

Feedstock recycling scenario

(^2) Chemical recycling scenario
Table 49 Relative difference between the impacts from the different end-of-life options vs. incineration with energy recovery for climate change
for biopolymers. A positive value means that incineration with energy recovery is preferable to the other end-of-life option. A negative value
means that incineration with energy recovery causes more environmental impact than the other end-of-life option.
N° case 1[MB] 1[OCT] 2[PLA] 2[MB] 2[BIO] 5[PLA] 6[PLA] 6[CE] 7[MAS]^1
Recycling ‐520% ‐50% 20%
Composting 20% 20% ‐130% ‐100% ‐110% 160% 160% 130%
Incineration without energy recovery
Landfill ‐40% ‐40% 20% ‐130% ‐110% ‐30%
Anaerobic digestion ‐10%
Studies n°3 and  4  do not include a comparison with incineration with energy recovery for this indicator and thus are not included
in this table
Incineration with energy recoveryversus other alternatives
1

1

Feedstock recycling scenario