Most landfills today encounter considerable problems when treating leachate due to the mixture of waste deposited there in the past. In order to prevent complex leachate being emitted, it is necessary to identify onsite sources of pollution and impose source separation of waste material. Parallel to source separation of household waste and other comparable wastes, a comprehensive study has been undertaken to examine various materials that can be used for recycling purposes. Such materials consist of ashes from incineration plants, foundries, contaminated soils, sewage sludge etc. These have been tested both in laboratory and in full scale studies at the Tveta plant to define which material can be re-used, for instance, to cover abandoned parts of the landfill. After landfills are closed, the amount of leachate will be reduced by a factor of 10 or more. Today, the Tveta Recycling Plant in Sodertalje, Sweden, produces approximately of 70 000 m(3) of leachate per year. A program has been initiated to separate different types of water, which are today all defined as leachate, at their source. For example, storm water from car parks or other hard surfaces used for sorting of building material at the plant should be separated and treated elsewhere.
