ELVs are collected and dismantled to remove the battery, tyres, fluids and any parts that can be re-used and the wreck is shredded. The metallic parts are separated by physical processes and recovered as ferrous scrap (iron and steel, comprising 70 per cent of the total vehicle waste) and nonferrous metals (5 per cent), all of which is recycled. The 25 per cent remainder is the automotive shredder residue (ASR), which is composed mainly of plastics, contaminated with any metallic and other parts that could not be separated. This is often disposed of in landfills as solid urban waste and is not recycled.
The study suggests that recovery rates for ELVs set in the EU Directive on end-of life vehicles1 will not be met until the volume of the ASR is further reduced. Treatment of the ASR therefore focuses on recovering any useable materials, reducing the volume of the ASR to cut down on the quantity that will end up in landfill, and recovering the energy from the petrochemical content of the plastics.
Three advanced methods of treating ASR were examined - incineration, pyrolysis and gasification. Public concerns about emissions produced from incinerating or burning the ASR meant this method was considered less environmentally friendly than pyrolysis. No disadvantages were found using pyrolysis, where heat was used to break down the organic material in the absence of oxygen. Treatment of the ASR by pyrolysis yielded ferrous and nonferrous metal contaminants, which could be recovered and recycled and oil which could be used as a secondary fuel. It also produced recoverable gas which could be reused as an energy source and a small volume of solid residue which would be disposed of in landfill.
Gasification was also considered a better option for treatment of the ASR than incineration, because the process produced fewer emissions. It also produced gas which could be used as a fuel source and residues that could be used in the construction industries.
Manufacturers are advised that incorporating end-of-life management principles into the early design and development stages of vehicle production can ensure maximum recycling when the vehicles reach end-of-life stage.