Recycling and composting
(i) Materials Recycling. The recovery of materials from waste and processing them to
produce a marketable product, for example, the recycling of glass and aluminium cans is
well established, with a net saving in energy costs of the recycled material compared
with virgin production. The potential to recycle material from waste is high, but it may
not be appropriate in all cases, for example, where the abundance of the raw material,
energy consumption during collection and re-processing, or the emission of pollutants
has a greater impact on the environment or is not cost-effective. Materials recycling
also implies that there is a market for the recycled materials. The collection of
materials from waste, where there is no end market for them, merely results in large
surpluses of unwanted materials and also wastes additional energy with no overall
environmental gain.
(ii) Composting. Decomposition of the organic, biodegradable fraction of waste to
produce a stable product such as soil conditioners and growing material for plants.
Composting of garden and food waste has been encouraged for home owners as a direct
way of recycling. It has been extended to the larger scale for green waste from parks
and gardens and also to municipal solid waste and to sewage sludge. The quality of
compost produced from waste, compared with non-waste sources, has been an issue
for waste composting, particularly in the area of contamination.