Fang-Ming Jin*, Atsushi Kishita* and Heiji Enomoto*

* Department of Geoscience and Technology, Graduate School of Engineering, Tohoku University

+ Correspondence should be addressed to Fang-Ming Jin:
(01 aoba aza aramaki aoba-ku, sendai-city 980-8579 Japan)

Abstract

Experiments on oxidation in supercritical water were carried out with a batch reactor system in order to treat organic waste with a high water content and low calorific value, such as organic garbage. 22 kinds of vegetables, meats and fishes were chosen. This study focused on understanding the differences or similarities in the oxidation reaction among selected types of garbage and the effect of reaction parameters. Certain selected vegetables were easily oxidized and no significant difference among them was found, but meats and fishes were more difficult to oxidize than vegetables. Beef suet was found to be the most difficult substance to decompose by supercritical water oxidation. No remarkable difference of kinds of meat and fish on the TOC decomposition was found. The intermediate residual product was acetic acid in all cases. To obtain a TOC decomposition higher than 99% in a 10 minute reaction, the reaction temperature must be above 400*C[Celsius degeree] in the case of vegetables and 450*C[Celsius degeree] in the case of meat and fish. By supplying excess H2O2 and/or increasing the temperature, the TOC decomposition can be accelerated. However, a further increase in the reaction time had little effect on the decomposition of the residual organic substance, that is acetic acid. The variation of water fill rate, that is the reaction pressure or the water density, in the range of 30 to 50% (35-58MPa) appeared to have little effect on the TOC decomposition.

Key words: organic garbage, waste treatment, supercritical water, SCWO, decomposition