Shoppers have earned more than £30,000 by recycling plastic bottles in the first supermarket trial of reverse vending machines.
The scheme, piloted by Iceland, rewards people with a voucher worth 10p for every deposit of a bottle bought at the shop.
It was rolled out to stores in Wolverhampton, Mold, Fulham and Musselburgh – as well as Iceland’s head office, in Deeside.
New figures show that 311,500 plastic bottles have been recycled so far.
The deposit machine accepted plastic bottles of up to three litres, which needed a barcode showing that they were sold by the shop.
Children were “particularly engaged” with the deposit machines and even educated and encouraged their parents to use them, the supermarket said.
Iceland has promised to share the findings of its research with the government.
Richard Walker, the supermarket’s managing director, hailed the move as helping to “eliminate” plastic from food and drink packaging.
“It’s clear from the results that consumers want to tackle the problem of plastic head on, and would be in support of a nationwide scheme,” he said.
In October, Environment Secretary Michael Gove committed to “working with industry to see how we could introduce a deposit return scheme for plastic bottles”.