The legal framework establishes criteria for the acceptance of waste at landfills. That means that certain types of waste require specific treatment prior to landfilling in order to meet the waste acceptance criteria (WAC). This project presents a compilation and evaluation of existing information on treatment methods and technology for selected types of “problem waste” that does not comply with WAC. For some waste types the same treatment methods may be applied to improve their properties in relation to reuse. Three waste streams were selected: bottom ash and residues from air pollution control from municipal solid waste incinerator, and shredder residues. Residues from air pollution control and from shredder constitute real problems in relation to landfilling, while the problems for bottom ash are more related to reuse. A brief discussion on the properties and treatment options for ashes from the incineration of biofuels (wood chips or straw) is also included. The report describes the landfill WAC in each of the Nordic countries. Next, the waste properties that may have to be improved to comply with the acceptance criteria are discussed, and a general overview of available waste treatment principles is given. Finally the properties, the potential problems associated with compliance with the landfill WAC, and the treatment options are described for each of the three waste streams. The treatment methods are described and evaluated in terms of technical efficiency, limitations, economy and compliance with appropriate landfill WAC.