Environmental Engineering Reference
In-Depth Information
Fig. 3.6
LCA for PET bottle recycling. (From Nakanishi
2003
)
Table 3.2
Environmental load of PET bottle production with and without recycling (1000 1.5 l
bottles) from Nakanishi (
2003
)
Process
Stage
Solid waste (kg)
CO
2
(kg)
NOx (kg)
SOx (kg)
Recycle
Collection
0
1.13
2.03
0.644
Transport
0
0.889
5.86
0.506
Flake production 7.7
14.6
35
18.7
Re-pellet
0.858
4.2
3.49
2.78
Total
8.56
20.8
46.4
22.6
Landfill
Collection
0
1.08
1.93
0.614
Shredding
0
1.22
1.01
0.81
Transport
0
0.446
2.94
0.254
Non-burnable
waste
55.21
2.75
5.88
1.68
consume more resources and provide a bigger environmental load than producing
new bottles.
LCA however allows us to examine this issue on the basis of more rigorous
methods than the cost comparison. Nakanishi (
2003
) followed the procedure in
Fig.
3.6
for the LCA on PET bottle recycling, which indicates the life cycle of a PET
bottle from the stage of crude oil production to that of waste-disposal or recycling.
As seen in the figure, inputs of resources and outputs of contaminant are counted
for each stage and summed up to obtain the final amount of solid waste or recycle
resin. Nakanishi carried out the LCA for the recycling of 1000 PET bottles of 1.5 l
and compared the amount of atmospheric emissions between recycle and landfill
of solid wastes. In this comparison, the amount of contaminant emission from the
new PET resin is included as well as from landfill for the disposal of the old bottles.
Table
3.2
shows the results of LCA of the emission of CO
2
, NO
x
and SO
x
. It is
clearly seen from Table
3.2
that the amount of solid waste and contaminant emitted
from recycle is much smaller than that from landfill.
