Food and garden rubbish is sorted and then cooked to produce rich compost at this waste management centre

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Ash Turner sizes up a four-metre-high, 60-tonne mound of food waste and garden rubbish and points out the problematic interlopers amid the grass clippings, hedge trimmings, mango seeds, calla lilies and biodegradable bags full of food.

“So that’s a biodegradable bag … that’s not … that’s oversized,” he says, pointing to a tree stump that will be too big to be broken down by the various machines in the plant.