资源环境科技发展态势分析平台

By Aisling Irwin

Can we simply magic plastics away? That’s the promise of biodegradable plastics – and they are at least part of the plastic waste solution, says Kevin O’Connor of University College Dublin, Ireland.

Perhaps the best-known biodegradable plastic is polylactic acid, or PLA. Made from maize starch or sugar cane, it has uses ranging from medical implants to packaging. O’Connor is working on fermenting sugars or plant oils, or even breaking down waste PET, to make polyhydroxyalkanoates (PHAs), a family of plastics that can be used to make bottles, films and glues.

The most popular biodegradable plastic on the market is probably Mater-Bi, a thermoplastic starch made by the Italian company Novamont from sugar, plant oils and even thistles. The hope is that wood chips and other biomass waste could eventually be used as feedstocks for biodegradable plastics.

Existing biodegradables generally need industrial conditions to break down, for example up to 12 weeks at 57°C for compostable plastics that decompose with food waste. Recycling firms don’t like them, complaining that they further contaminate waste streams, while industrial food composters fear that people will get confused and put conventional plastic in food waste collection bins as well, rendering the resulting fertiliser worthless.

Biodegradable plastics that can rot unaided in a ditch or in landfill are harder to make. Possible sources include plant sugars and starches, and also seaweed, which doesn’t need fresh water and fertiliser to grow. …

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