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500 Million plastic bags a year


May,2008

A Waterloo teenager has found a way to make plastic bags degrade faster

We produce 500 billion a year worldwide and they take up to 1,000 years to decompose. They take up space in landfills, litter our streets and parks, pollute the oceans and kill the animals that eat them.

Now a Waterloo teenager has found a way to make plastic bags degrade faster in three months, he thinks. Daniel Burd's project won the top prize at the Canada-Wide Science Fair in Ottawa.

He knew plastic does eventually degrade. His goal was to isolate the microorganisms that can break down plastic.

First, he ground plastic bags into a powder. Next, he used ordinary household chemicals, yeast and tap water to create a solution that would encourage microbe growth. To that, he added the plastic powder and dirt. Then the solution sat in a shaker at 30 degrees.

After three months of upping the concentration of plastic-eating microbes, Burd filtered out the remaining plastic powder and put his bacterial culture into three flasks with strips of plastic cut from grocery bags. As a control, he also added plastic to flasks containing boiled and therefore dead bacterial culture.

At 37 degrees and optimal bacterial concentration, with a bit of sodium acetate thrown in, Burd achieved 43 per cent degradation within six weeks.

The plastic he fished out then was visibly clearer and more brittle, and Burd guesses after six more weeks, it would be gone. He hasn't tried that yet.

To see if his process would work on a larger scale, he tried it with five or six whole bags in a bucket with the bacterial culture. That worked too.

Industrial application should be easy, said Burd. "All you need is a fermenter . . . your growth medium, your microbes and your plastic bags."

The inputs are cheap, maintaining the required temperature takes little energy because microbes produce heat as they work, and the only outputs are water and tiny levels of carbon dioxide -- each microbe produces only 0.01 per cent of its own infinitesimal weight in carbon dioxide, said Burd.

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