Christmas time, while a great deal of fun can typically be a time of excess and quite frankly waste. Plastic wrappings around Christmas gifts and toys can be one of the biggest causes of extra rubbish which goes to land fill over the festive period, thanks in the most part to much of it being unrecyclable. On average we each consume 120 grammes of plastic wrapping on Christmas gifts, most of which is of a type which is almost impossible to recycle.
But now researchers at the University of Warwick have devised a new technique which could process 100 per cent of Christmas and other household plastic instead of the tiny fraction that currently actually gets processed – typically only 12 per cent. Although many householders spend time separating their recyclable and non-recyclable plastics, some of the plastic is sent for recycling still goes to land fill or simply burnt. Sadly it is often simply too time consuming to separate out and clean the various types of plastics as it requires significant laborious human intervention. An additional problem is that often objects are made of more than one plastic that would require different treatments.
However University of Warwick engineers have come up with a simple process that can cope with every piece of plastic waste and can even break some polymers such as polystyrene – back down to its original monomers (styrene in the case of polysterene).
The Warwick researchers have devised a unit which uses pyrolysis (using heat in the absence of oxygen to decompose of materials) in a “fluidised bed” reactor. Tests completed in the last week have shown that the researchers have been able to literally shovel in to such a reactor a wide range of mixed plastics which can then be reduced down to useful products many of which can then be retrieved by simple distillation.
The products the Warwick team have been able to reclaim from the plastic mix include: wax that can then be used as a lubricant; original monomers such as styrene that can be used to make new polystyrene; terephthalic acid which can be reused in PET plastic products, methylmetacrylate that can be used to make acrylic sheets, carbon which can be used as Carbon Black in paint pigments and tyres, and even the char left at the end of some of the reactions can be sold to use as activated carbon at a value of at least £400 a tonne.
Plastics are made from oil, a resource neither clean nor abundant. By being able to recycle all plastics, the use of oil could be significantly reduced. Plastics are used extensively in car interiors, recycling it could improve end-of-life recoverability of vehicles.
The lead researcher on the project, University of Warwick Engineering Professor Jan Baeyens, said:“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 worth of recycled chemicals and each plant would save £500,000 a year in land fill taxes alone. As the expected energy costs for each large plant would only be in the region of £50,000 a year the system will be commercially very attractive and give a rapid payback on capital and running costs.”
