In Finland, some 40 to 60 percent of the collected plastic waste is ultimately, for whatever reason, unsuitable for mechanical recycling and ends up being incinerated instead. Multi-layer plastic films, for example, or plastic that has been through a number of recycling loops already are both instances where mechanical recycling is not the right solution.
A two-year project conducted at VTT Technical Research Centre of Finland – the Business Finland WasteBusters’ project – has now demonstrated that chemical recycling offers an ecologically sound alternative to incineration and possibly to mechanical recycling as well.
The method applied in the project involved a pretreatment and pyrolysation of the long polymer chains of the plastics and their mixtures. The resulting pyrolysis wax or oil may be further processed at the refinery.
The pre-treatment step, in particular, is important for arriving at a cost-effective concept, said Anja Oasmaa, Senior Principal Scientist at VTT.
“There are all kinds of films as well as both dense and porous pieces together in plastic waste, which makes it difficult to handle. We managed, however, to make it homogenous with the Modix-extruder developed by VTT.”
Until now, the supply of plastic waste in Finland has been considered too small for pyrolysis. Scientists, however, calculated in the project that a network of approximately ten pyrolysis plants could prove profitable if pyrolysis of plastic waste and wood waste were combined. Bolting on pyrolysis plants to waste recycling plants could be a viable approach.
”Companies are interested in the fact that plastic waste can be turned into other chemicals besides plastics, which will then replace virgin fossil raw materials in a sustainable manner. We want to develop this line of business with sustainable solutions in close cooperation with companies”, said Oasmaa.
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