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DOE Pulse
  • Number 325  |
  • November 22, 2010

Harnessing bacteria power to make eco-friendly plastic from waste

All three composite boards contain wood waste and plastic. The dark board (left) contains two special ingredients: plastic made by bacteria, and the same bacteria that made the plastic–by eating wastewater.

All three composite boards
contain wood waste and plastic.
The dark board (left) contains
two special ingredients: plastic
made by bacteria, and the
same bacteria that made the
plastic–by eating wastewater.

Standard wood-plastic composite boards are about half sawdust and half petroleum plastic. But a composite board produced by researchers at the Department of Energy’s Idaho National Laboratory, the University of California, Davis, and Washington State University contains nearly equal proportions of sawdust, plastic made by bacteria, and the same harmless bacteria that made the plastic — by eating wastewater. Under the heat and pressure of processing, the same fats and proteins that had been the building blocks of the bacterial cells become building material of another sort. The bacteria board is as strong and durable as a standard wood-plastic composite, but is produced entirely from waste with minimal environmental impact.

Manufacturing petroleum plastics requires a hefty input of fossil fuels and releases significant amounts of air pollution and greenhouse gases. Producing bacterial plastics on an industrial scale isn’t any cleaner:  large quantities of energy and chemicals go into producing refined sugars to feed the bacteria and purifying the plastic from bacterial stew that produces it. Feeding the bacteria on free wastewater and skipping the purification step slashes the cost, energy and chemical consumption of bacterial plastic production. The research team calculated that if composites made with unrefined bacteria plastic replaced half of all wood-plastic composite building material by 2020, the building industry could save the energy equivalent of more than 2 million tons of coal and prevent the release of several hundred tons of air pollution each year.

[Sandra Chung, 208/526-1919,
sandra.chung@inl.gov]