【Paper】
Survey on Current State of Landfilled Waste, especially on Incombustible Waste
Yasumasa Tojo*, Nobutoshi Tanaka*, Toshihiko Matsuto*, Yoshitada Kakuta*, and Takayuki Matsuo*
* Graduate School of Engineering, Hokkaido University
† Correspondence should be addressed to Yasumasa Tojo:
（Kita 13 Nishi 8, Kita-ku, Sapporo, 060-8628 Japan）

Abstract
The Basic Plan for Promotion of a Recycle-oriented Society proposes as its national goal to reduce the amounts of landfill waste in half by the year 2010. In order to achieve this goal, it will be necessary to understand what types of waste are effective in reducing the amount, and how the reduction can be achieved. In this study, a questionnaire survey among municipalities was conducted to better understand the current state of directly landfilled and incombustible waste. Areas which were checked include types of waste, treatment methods, and the quantities being disposed of.
Results showed that: 1）Ceramic, glass, and metal waste are collected as incombustible waste by over 65％ of the municipalities; 2）Incombustible waste is shredded and sorted in almost 40％ of the municipalities, while direct landfilling has been adopted by about 30％ of the municipalities; 3）Using cluster analysis, municipalities were categorized into 5 groups based on their incombustible waste items. It was found that in one group, collecting only small incombustible items, the quantity of collected and landfilled waste amounts were almost half that of other groups; and 4）Even if a municipality collects various incombustible waste items, 60-80％ of the waste quantity could be reducible using shredding and sorting treatment.

Key words: landfilled waste, incombustible waste, shredding and sorting, direct landfilling, cluster analysis