Environmental Engineering Reference
In-Depth Information
In the United States, only 8.2% of the plastic in MSW was recovered for
MSW is sorted, cleaned, and reprocessed into useful products. Separating
plastics from other waste is carried out in MRFs to obtain a single stream
of mixed plastic products that often contains varieties of plastics unsuitable
for recycling. It has to be further sorted to separate out popularly recycled
varieties such as poly(ethylene terephthalate) (PET) and high density
polyethylene (HDPE) from the mix. While hand sorting is possible, most
modern MRFs use faster mechanical sorting. Plastic-only streams presorted
at source by consumer is also processed by MRFs where machine sorting
of plastics into different classes (based on near infra-red spectral signature)
is particularly convenient and efficient. With source-separated all-plastics
streams, the residuals (un-recyclables) are relatively low and cleaning of the
material is easier. However, in the us only resin types such as PET or HDPE
where there is a ready market for the recovered resin is recycled; the rest of
the plastic waste is landfilled.
Figure 9.2
Generation and recovery of the plastics in municipal solid
waste stream in the United States. Source: USEPA.
Plastic waste is classified into several subcategories in the USEPA
compilation and the fraction of specific resins in each, identified. It is
instructive to study the data (despite their limited reliability) to identify
