Alexandre Allard and Danny Luong of Quebec City received their $5,000 US award and prize sculptures from Crown Princess Victoria of Sweden at a ceremony Tuesday evening in Stockholm as part of World Water Week. (Stockholm International Water Institute)

A new way to clean up polystyrene waste and stop it from fouling waterways has won two Canadian teens the 2010 Stockholm Junior Water Prize.

Alexandre Allard and Danny Luong of Quebec City, who are both 19, received their $5,000 US award and prize sculptures from Crown Princess Victoria of Sweden at a ceremony Tuesday evening in Stockholm as part of World Water Week.

The two developed a technique that uses bacteria to break down the foam plastic used in many disposable cups, fast-food containers and packing materials.

Allard, who has just started his first year at McGill University, said he and Luong were inspired after reading a report about how polystyrene breaking down in the ocean can release toxic molecules.

"This gave us the idea that maybe polystyrene biodegraded," Allard told CBC News in a phone interview from Stockholm.

The two longtime friends, who went to high school together at Séminaire des Pères Maristes in Quebec City, decided to look for bacteria that might be able to break down expanded polystyrene.

They went to the Cap-Rouge dump and collected soil in areas where there was a lot of polystyrene in order to find bacteria that could survive in the presence of the plastic foam.

Those bacteria — two kinds of pseudomonas and one kind of streptomycin — were placed in flasks with sterile water, no food and about a gram of polystyrene, which is about two-thirds the mass of a small polystyrene coffee cup. The experiment showed the bacteria could break the plastic down into carbon dioxide.

3 kinds of bacteria work together

Under optimal conditions, the bacteria could degrade 70 per cent of the polystyrene into carbon dioxide within two weeks and all of it within three weeks.

While most of the degradation was done by one kind of pseudomonas, having the other two kinds of bacteria present resulted in more degradation than the sum of the degradation from each kind of bacteria individually.

"This leads us to believe there's one bacteria that does most of degrading, but the other bacteria actually help it," Allard said, adding that each kind of bacteria may produce different degradation enzymes.

The pair started the research in August 2009 and finished it in February 2010, when Allard was studying at Collège regional Champlain campus St-Lawrence and Luong was at Cégep Sainte-Foy, where he is still studying.

They used the equipment in the labs at their respective colleges, and also borrowed equipment from the University of Laval.

They hope their research will be used to clean up styrofoam waste, although Allard said a lot more testing needs to be done, especially tests in the field rather than just in the lab. For now the bacteria remain stored in a freezer at one of the colleges.

'Honoured to be here'

Allard suggested some of the enzymes produced by the bacteria, which initially break styrofoam down into styrene and bisphenol A, can also be used to recycle styrofoam.

In the meantime, Allard and Luong were having a great time in Stockholm and were scheduled to give flowers to the queen of Sweden on Friday.

"It's been absolutely incredible," Allard said. "We're very honoured to be here."

Allard and Luong were among thousands of students aged 15 to 20 who competed in national competitions around the world to represent their country at an international competition held during the annual World Water Week meeting in Stockholm, which runs Sept. 3-11.

They beat out water-related projects on topics of environmental, social or technological importance from more than 30 countries. The conference is hosted by the Stockholm International Water Institute.