Microsoft Word - Environmental benefits of recycling 2010 update.doc

Crop growing and

harvesting

Starchextraction

Production of

intermediates products

Electricity

Biopolymer shaping

Biopolymer product

Use

Incineration Anaerobic digestion Landfill Composting Recycling

Material production

and use

Disposal & recovery

Energyexport to

the grid

Emissions from

landfill

Alternative use of

incineration

capacity

Processing

Marginal material

Ratio of virgin

material

subsitution

Co‐products

Heat/steam

Avoided material

production

Degradation rate

Compost use

Crude oil

Post‐consumer waste

Collection

Electricity

Marginal material

Co‐products

Heat/steam

Figure 24 The biopolymers system and key parameters

3.4.2 Comparison between the various end-of-life options

Alternatives compared

The end-of-life options covered by the selected studies are:

 Recycling

 Composting

 Incineration with energy recovery

 Incineration without energy recovery

 Anaerobic digestion

Table 46 gives an overview of the alternatives that are compared within each case. It also illustrates how often
each end-of-life option is represented. It can be seen that incineration without energy recovery and anaerobic
digestion are analysed in one and two studies, respectively. In fact, incineration without energy recovery is no
longer common and will inevitably disappear in the near future. As anaerobic digestion is not a fully mature
option for biopolymers, very few studies could be found since little data is available about the technology. The
results obtained should thus be interpreted with care, especially as the number of cases is not sufficient to assess
the validity of the results. It should also be noted that in this chapter recycling refers to three types of recycling:

 mechanical recycling, where plastics are shredded into pellets or granulates and serve as new raw

materials. This corresponds to the usual definition for recycling;

 feedstock recycling, which is defined as a change in the chemical structure of the material, where the

resulting chemicals are used for a purpose other than producing the original material; and

 chemical recycling, which implies a change in the chemical structure of the material, but in such a

way that the resulting chemicals can be used to produce the original material again (monomer

recovery).