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Win-win with biodegradable plastics from toxic waste

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08.09.2004

A biodegradable plastic made from toxic waste could solve pollution problems, scientists from Dublin announced today (Wednesday, 08 September 2004) at the Society for General Microbiology’s 155th Meeting at Trinity College Dublin.

The team from University College in Dublin have demonstrated that bacteria can use styrene, a toxic by-product of the polystyrene industry, to make a type of biodegradable plastic, polyhydroxyalkanoate, known as PHA.

Styrene is found in many types of industrial effluent, and in the United States alone accounts for 25 million kilogrammes (about 25,000 tons) of hazardous waste every year. Styrene causes lung irritation, muscle weakness, and affects the brain and nervous system in people and animals, so a method of disposing of it safely would have health as well as economic benefits.

“The current methods of dealing with waste styrene include underground injection, spreading it on land, or burning it in incinerators to generate energy, which results in toxic emissions,” says Patrick Ward from the Department of Industrial Microbiology at University College, Dublin. “We all use plastics in our everyday lives from disposable drinking cups to car parts, so millions of tons are made, used and discarded every year. But the slow rate of degradation of polystyrene means that it can last thousands of years in our environment.”

The scientists have discovered a strain of bacteria called Pseudomonas putida which can convert the dangerous petrochemical waste product, styrene, into a biodegradable plastic. The bacteria act as a small factory and storage unit, accumulating the plastic, PHA, inside themselves.

“We found that all of the available styrene was converted by the bacteria into plastic, and thus this process completely removes the pollutant,” says Dr Kevin O’ Connor, also from the Department of Industrial Microbiology at University College, Dublin. “The plastic made by the bacteria is an elastic type polymer, which would have a wide range of industrial and commercial uses such as medical implants, scaffolds for tissue engineering, wound management, drug carriers, plastic coating of cardboard and heat resistant plastic.”

The University College team now hopes to improve the process by increasing the scale of the operation, and increasing the efficiency of the bacteria’s action, to make commercially useful amounts of the PHA plastic. The conversion of styrene waste will be welcomed by industry, regulatory and environmental bodies since it removes a toxic waste material while generating a valuable, biodegradable and non-toxic plastic.

Faye Jones | Source: alphagalileo
Further information: www.sgm.ac.uk

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