Isamu WATANABE

Evaluation of Anaerobic Co-digestion System of Sewage Sludge and Garbage

by Life Cycle Assessment

Toshiya KOMATSU Shuji HIMENO Shoichi FUJITA


Anaerobic digestion of garbage using sludge digesters in sewage treatment plant is expected to be an effective energy recovery method from garbage.
In this study , we tried to evaluate anaerobic co-digestion system of sewage sludge and garbage by Life Cycle Assessment. We presumed the city population of 200,000 and compared five scenarios for garbage treatment : ‡Tincineration, incineration after anaerobic co-digestion( treatment ratio rate of garbage‡U30 “ ,‡V80 “ ) , composting after anaerobic co-digestion ( treatment ratio of garbage ‡W30 “ ,‡X80 “).

As categories for evaluation , we set up the cost , amount of energy consumption , and emission of CO2ENOXESOXEdioxinsEheavy metals. As the results , there was no remarkable difference between scenarios in cost. In case of the environmental loads , the scenario‡X was the smallest.

Furthermore , we integrated assessment among the environmental impact categories by the Distance to Target method. The scenario‡X was also the most excellent in this evaluation method.

It is concluded that the anaerobic co-digestion system is effective in case that treatment ratio of garbage is high and composting after co-digestion is applied.