The following was taken from a press information of PlasticsEurope Deutschland on 24 January 2006:

“A basic study ordered jointly from the Federal Environmental Office and PlasticsEurope Deutschland e.V. concerning the quantities of plastic waste and the potential ways of recycling  (with exception of packaging), which was hitherto disposed of in landfills or eliminated in waste incineration plants, is in hand now …

Considering the ecological and economical aspects, material recycling would be the best solution for those quantities of plastic waste which can be collected and separated as clean waste, e.g. large pipes. But for dirty and mixed plastic waste – which makes up the lion’s share - , large-scale use as feedstock material or energy recovery forms scores best.
You can read the press report under www.plasticseurope.org.
The study can be found under www.plasticseurope.org under the menu item “publications/technical reports (or Publikationen/Technische Reports)”.