Although major advances have taken place in recent years in the engineering and control of landfill operations, the generation of highly polluting leachates as water percolates through wastes remains a major consideration. Despite the fact that many leachates contain high proportions of readily degradable organic materials and are frequently treated successfully at sewage treatment works for discharge to surface waters, in the United Kingdom very few facilities have been constructed on landfill sites for the treatment of leachate.
In the Federal Republic of Germany research, which has been stimulated by changes in legislation, has resulted in the construction of several relatively sophisticated leachate treatment plants since the later 1970s. These have been designed to very high standards, but only at very high costs (of up to £4 for every m3 treated).
It is considered that on-site aerobic biological treatment systems will become more common in the UK, as individual landfill sites continue to increase in size and also as research results allow process designs to be optimized further. It is therefore appropriate that geological assessments of the suitability of landfill sites are made in the light of research and experience, in particular as advances are made in the technology of leachate treatment.