Candy becomes plastic

Foto: Jos Wassink

Photo: Jos Wassink

The cream-coloured wastewater from the Mars, Bounty and Twix bars is filled with fatty acids and sugars. A small portion of this was used to feed plastic-producing bacteria, which produce long polyesters (polyhydroxyalkanoates or PHA), a type of body fat for the bacteria and a usable bio-polymer for people. Jelmer Tamis (biotechnology, Applied Sciences), who supervised the experiment on-site, brought the amount of PHA extracted from the wastewater to a new record: 1 gram of plastic from 3 grams of waste. This reduced the price of the substance to about €1 per kilogram, making it less expensive than polyethylene. Price is an important factor for determining whether the bio-plastic will be used in the industry.

The mobile test system is the result of fourteen years of research by the department of environmental biotechnology, which has already led to the discovery of Plasticicumulans acidivorans. These superbacteria are allowed to feed on the candy wastewater for five hours until they almost explode. The water is then tapped and harvested: more than 70% of the dried mass consists of PHA bio-plastic.

In the Netherlands, supplementary research is being conducted on the material properties and application of the bio-plastic. This is taking place within a programme of technology foundation STW, in collaboration with the universities of Wageningen and Eindhoven.

In May, the pilot plant relocated to a cardboard factory in Groningen, whose wastewater contains many fatty acids.

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