A MAJOR environmental misconception is to regard sewage, raw or semi-treated, as obnoxious waste to be disposed of as quickly as possible. In fact, it should be viewed as a valuable resource and managed accordingly. Indeed, the possibilities are endless.

For a start, sewage could supply all our phosphate needs (phosphates are essential to most biochemical products and processes) far more cheaply and reliably than our current practice of importing mineral phosphate from North Africa and Russia.

Also, as we are just beginning to discover, sewage is home to many potentially very useful bacteria that promise all kinds of exciting new possibilities - medical, technological and environmental.

Given the astronomical rise in human populations, systematic recycling of sewage is an urgent necessity. Apart from the immediate practical benefits, which would be enormous, it would radically improve our relations with the natural environment.

Tony Kelly, Crook, Co Durham.