(best examples and good practices) on household organic waste ...

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4.5. Mechanical <strong>and</strong> Manual Operation
There are two types of sorting processes which are used today in waste recovery
facilities. The Manual sorting, which produce higher quality product from the
mixed waste stream, but is not so efficient because of the very slow processing
rates. Manual sorting also yields more rejected materials <strong>and</strong> misses a
considerable portion, for example HDPE <strong>and</strong> PET plastics waste stream due to
the inability to target certain container shapes. If a plastic substance cannot be
distinguished with the naked eye, it cannot be efficiently manually sorted <strong>and</strong>
will therefore not be separated. Furthermore, it is extremely difficult for a
sorter to distinguish between PVC <strong>and</strong> PET plastics, but these resins can be
separated more quickly <strong>and</strong> accurately with the use of automated systems.
(Dubanowitz., 2000) The same happens to kitchen waste which cannot be
separated from the mixed waste stream as easy as in source separation.
When there are bulky items such as (appliances, furniture, etc.) <strong>and</strong> specified
contaminants (e.g., hazardous waste) must be separated prior to mechanical
separation process in order for the further treatment of these materials to be
efficient. Manual separation is also applicable to the removal of contaminants
from source-separated materials. (Contaminants refers to components other
than the materials specified for separate collection.). (Tchobanoglous <strong>and</strong> Kreith.,
2002)
manual separation (Picture 7.) of materials usually includes a sorting belt or
maybe a table, which contains the mixed waste stream. Workers are stationed
at the right <strong>and</strong> at the left of the belt for the materials separation. Hoppers or
other receptacles for receiving removed items are positioned within easy reach
of the sorters.
Picture 7.: Manual Waste Sorting
(Portal of Prague., 2010)