Pre-processing is applied during MSW composting
for one or more of the following reasons.
To increase the proportion of compostable materials in the
feedstock – Glenn 1991 – MSW contains a high proportion of non-compostable
or poorly compostable material, hence composting the whole MSW stream is inefficient
and leads to a very low grade of compost. See also the Critical Review Section,
Feedstocks and composition - Physical characteristics.
To improve feedstocks for other recovery options Removal
of compostable materials (and materials removed in parallel such as glass)
can improve the efficiency of down stream sorting processes to recover energy
and dry recyclables in mechanised plant (Anon 1991, Barton 1983, 1984 and