Chemical or thermal decomposition
of plastics to create monomers and other intermediate chemicals,
used as feedstock
the waste as a fuel to release energy
Burning rubber "crumb"
from old tyres in cement kilns
Using plastic waste from nylon recycling
as heat at other stages in the process
Open and Closed Loop Recycling
In some cases waste from one
product is recovered and used in the manufacture of another, lower
quality product. This may be referred to as open loop recycling.
It reduces the amount of fresh feedstock needed, and the amount
of waste going to landfill.
Sometimes waste material is used to manufacture the same product
with no loss in quality - the process can theoretically be carried
on indefinitely. In practice there will always be some loss of
quantity so small amounts of "top-up" feedstock
will be needed. This may be referred to as closed loop recycling.
Recycling Process Chemicals and Catalysts
Chemical manufacturers will always recycle materials
used in processes as it makes good economic sense. Sulphuric acid,
mentioned above, is routinely recycled.
The manufacture of nylon by conventional methods
generates dinitrogen monoxide (N2O), an atmospheric
pollutant. By using an alternative reaction, it is possible to
recycle N2O within