Plastics You Could Eat - Recyling

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Just in the UK, we produce enough plastic to fill the Royal Albert Hall - three times every single day. That's about six million tonnes a year. And most plastics last indefinitely, taking thousands of years to disintegrate. If the Romans had made plastic, we'd still have their waste with us today. If we don't want our great-grandchildren to have to live on mounds of old plastic, we should try to address the issue.

Recycling plastic is an option, and works well for bottles, but it can cost more in energy terms than using virgin plastic. Burning waste plastic to harness the energy is another option, but the gases released by some plastics are very toxic. The case for biodegradable plastics is strong, especially where packaging gets dirty and can't be re-used.

Several plastics masquerade as biodegradable, but actually break down into tiny invisible bits that could affect the soil and animals such as earthworms. Of the few plastics that are genuinely biodegradable, many contain toxic residues from catalysts. One plastic, that's biodegradable and contains no nasty residues, is called PHB, polyhydroxybutyrate.

Bugs make plastic

'Bugs make plastic' ran the headline when PHB was first commercialized in the early eighties. Most plastics are made from oil but this one is made naturally, all the time, by bacteria. And the supply is limitless. Almost any kind of bacteria store up energy as 'fat' available to be used later by the bacteria. When extracted, this bacteria fat solidifies into a polymer very similar to traditional plastics like polythene. To make PHB on a big scale you just fatten up bacteria with glucose in giant fermenters and effectively 'brew' the plastic.

Not only do they make it - bacteria can eat it. PHB is so rich in energy for bugs, they can't resist it. A discarded piece of PHB will be gobbled up by bacteria in the environment. The time it takes for PHB to degrade just depends on the concentration of bacteria: in the sea it takes PHB a few months to break down; in a sewage works it takes just a few weeks; but on your kitchen or bathroom shelf, it will last decades.

Jamie Hobbs PHB cystals spiral out from a central point forming beautiful Spherulites

Why isn't PHB filling up our supermarket shelves?