A total of 187 billion nappies are thrown away each year, but unlike bottles, cans or cardboard, nappies are hard to recycle.

But now engineers have devised ways of recovering the plastic and other materials inside them.

A pilot plant has opened in Treviso, Italy, backed by the world’s largest maker of nappies Procter & Gamble.

Eventually the plan is to offer parents across the city individual nappy bins which will then be picked up by trucks in separate waste collections.

Science editor David Shukman reports.