Of 30 contracts signed, 25 corresponded to a purely contractual PPP (concession) and 5 to institutionalised PPPs (mixed companies). The trend before 2004 should be treated with caution, as waste classification in Portugal was subject to change following the requirements of the EC Regulation on waste statistics (2150/2002/ EC). They integrate seven waste management units: classification (including laboratory), sorting and transfer; stabilisation; organic waste treatment; recovery of contaminated packaging; soil decontamination; physico-chemical treatment; and hazardous waste landfill.