Kiyoshi Kawamura*
* Center for Environmental Science in Saitama . Director
(914 Kamitanadare, Kisai-machi, Kita-Saitama-gun, Saitama 347-0115 Japan)

Abstract
Recovery of resources from bio-wastes has become a major issue. Currently various laws and regulations related to waste management have been amended or enacted to establish a new social scheme based on resource circulation. However, it is very difficult to accomplish, especially for municipal wastes, because the social system for separate collection and reuse of bio-wastes such as garbage has not yet been established. Furthermore, only a few technologies are available to convert bio-wastes to resources, under the wide-spread waste management system of treating collected municipal wastes in incinerators before final disposal.
In this paper, general ideas of bio-wastes recycling and various technologies for resource recovery of bio-wastes are introduced. Some aspects of anaerobic digestion methods for methane recovery are then summarized; the principle of anaerobic digestion, characteristics of each type of bio-waste in consideration of methane production, and the outlines of the newly developed systems and processes including those applied in Japan.

Key words: bio-wastes, technologies for resource recovery, methane recovery, wet digestion, dry digestion