Two phase anaerobic digestion
AssigneeInstitute of Gas Technology
InventorsSambhunath Ghosh, Donald L. Klass
Life of this patent
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Abstract
An improved two phase anaerobic digestion process in which an initial phase continually receives an organic feed for short detention times of less than two days under conditions which efficiently liquefy and breakdown the feed to lower molecular weight acids and other intermediates for conversion to methane. A succeeding phase is operated to treat the lower molecular weight acids and intermediates for detention times of about two to about seven days under conditions which efficiently lead to production of methane. The feed is loaded in the first phase at rates from about 1 to about 10 pounds of total organics per cubic foot per day; and the products from the initial phase are loaded in the succeeding phase at rates of about 0.1 to about 0.5 pounds total organics per cubic foot per day.
Claims10
A method for producing methane gas by a two phase anaerobic digestion of solid organic waste and biomass containing insoluble materials which includes the improved steps of:
- continuously delivering said feed to an acid phase digester at a loading rate of about 1 to about 10 lb. total organics per cubic foot-day,
- fermenting the feed in the acid phase digester under anaerobic conditions for a detention time of about 1/2 day to about 11/2 days, at a ph between about 5-6 and a temperature between about 20.degree.-40.degree. C.,
- conveying the resultant acid effluent to a separate methane phase digester at a loading rate up from about 0.1 to less than about 2 lb. of total organics per cubic foot-day,
- fermenting the acid effluent in the methane phase digester for a detention time of about 2 to about 7 days, at a ph between about 6.8 - 7.4, and a temperature between about 20.degree.-65.degree. C.,
- removing the methane for collection, and
- removing the feed effluent from the methane phase digester to process the solid and liquid components of the effluent.
Dependencies are inferred from the claim text.