Waste
It is better to prevent waste than to treat or clean up waste after it is formed.
Chemical products should be designed so that at the end of their function they do not persist in the environment and break down into innocuous degradation products.


(Green Chemistry Principles, Dr. Paul Anastas et al)

[We should] …eliminate our contribution to systematic increases in concentrations of substances produced by society.

This means systematically substituting certain persistent and unnatural compounds with ones that are normally abundant or break down more easily in nature, and using all substances produced by society efficiently.

(The Natural Step)
Waste is a fact of life
All living organisms generate waste of some sort, but natural materials will break down and continue to be used in biochemical cycles. In contrast, the manufacture of synthetic substances often creates waste that persists for long periods in the environment, or may adversely affect living organisms.

The total UK waste per year is in excess of 400 million tonnes. Only 7% of this is from domestic sources.
diagram: UK waste sources

Economics
In the chemical industry, waste always costs money because:

  • A proportion of the feedstock is not being converted into useful products
  • Additional chemicals, energy and equipment are needed to treat the waste
  • Disposing of waste safely can be expensive

It is in the interests of industry to reduce these to a minimum, and this is best done by reducing the amount of waste generated in the first place, rather than by treating it afterwards.

The UK poly(propene) manufacturer, Basell Polyolefins, used to burn unreacted propene in a boiler and the excess was flared (burnt). The addition of a recovery unit has considerably reduced the amount of waste and collects over 3000 tonnes of propene per year. For more information see the Sustain-Ed site

diagram: hierarchy of waste managment

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