It is estimated that only about 12 percent of plastic sent to depots actually gets recycled. Because of problems such as glued-on paper labels and different types of plastic combined in one product, the rest goes to the landfill or is burnt.
Scientists at the University of Warwick have now devised a system that could recycle 100% of household plastic.
The Warwick system uses pyrolysis within a fluidized bed reactor. Pyrolysis is the use of heat in the absence of oxygen for the decomposition of materials, while fluidized bed reactors pass a gas or liquid through solid granular material at high velocity, causing it to behave like a liquid.
The researchers shovel a wide variety of mixed plastics into the reactor. These are then broken down into useful elements that can be retrieved through distillation. Those elements included wax, monomers such as styrene (for making polystyrene); terephthalic acid (used in PET plastics); methylmetacrylate (used to produce acrylic sheets) and carbon. The char left over at the end of the process could be sold as activated carbon.
Lead researcher Professor Jan Baeyens said that "We envisage a typical large scale plant having an average capacity of 10,000 tonnes of plastic waste per year. In a year, tankers would take away from each plant over £5 million (US$7.7 million) worth of recycled chemicals.”