【Paper】
Carbonization of Household Waste for Recycling and Thermal Pre-treatment for Landfill Disposal
Toshihiko Matsuto*, Nobutoshi Tanaka*, Yoshitada Kakuta**, Yasumasa Tojo* and Takayuki Matsuo*
* Laboratory of Solid Waste Disposal Engineering, Hokkaido University
** Recyclable Resource Assessment Laboratory, Hokkaido University
† Correspondence should be addressed to Toshihiko Matsuto:
Laboratory of Solid Waste Disposal Engineering, Hokkaido University
（Kita 13 Nishi 8, Kita-ku, Sapporo, 060-8628 Japan）

Abstract
Residential waste was carbonized as a means of fuel production, metal recovery, and pre-treatment for landfill. Tested materials were combustible waste, incombustible waste and bulky waste, which were collected from a residential area and a shredding facility.
Char product from bulky waste showed good quality for fuel due to high wood content and potential recovery of metal such as Cu. The quality of char from the other two types of waste was low, but the leaching of heavy metal was minimized and organic contents were reduced, showing its effectiveness as a pre-treatment for landfill disposal. Washing treatment could also reduce chlorine contents enough for fuel use. Though both screening after ball milling and density separation were effective in reducing ash contents, the former was more practical because of its simple process.

Key words: carbonization, residential waste, ash removal, recycling, pre-treatment for landfill