US 6,143,176 AGranted

Method of converting organic wastes to valuable resources

AssigneeEbara Corporation

InventorsSadasuke Nagamatsu, Tsutomu Higo, Toshio Fukuda

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Abstract

The improved method of converting organic wastes to valuable resources comprises a methane fermentation step (4) in which a slurry of organic waste is retained for fermentation in an anaerobic digester to thereby generate a methane-containing gas and a fermentation slurry, a hydrothermal treatment step (11) in which the fermentation slurry is subjected to a hydrothermal reaction to thereby generate a carbon slurry, and a concentrating step (14) in which an aqueous phase is separated from the carbon slurry to thereby yield a concentrated carbon slurry having a high heating value. The method is capable of performing an effective hydrothermal treatment on a slurry of low water content, prevents the slurry from putrefaction during retention in the process and it yet is capable of effective treatment of the aqueous phase of the slurry after the hydrothermal treatment.

Claims8

Dependent claims

A method of converting organic waste into valuable resources, which comprises:

(a) a methane fermentation step in which a slurry of organic waste is retained in an anaerobic digester to generate a methane-containing gas and a fermentation slurry;
(b) A hydrothermal treatment step in which said fermentation slurry is maintained at a high temperature of from about 250.degree. C. to about 350.degree. C., at a high pressure of from about 50 to about 200 atmospheres, which is higher than a saturation pressure at the high temperature, for 10 minutes to 2 hours, to conduct a hydrothermal reaction to generate a carbon slurry containing a solid phase which consists of char having a high carbon content, oils and an aqueous phase including water soluble organic compounds;
and
(c) a concentration step in which said carbon slurry yields a concentrated carbon slurry having a high heat value by separating the aqueous phase which is returned to said anaerobic digester.

1 more element

Dependencies are inferred from the claim text.