Patent ID: 8962309
Filing Date: 2015-02-24
Classification: C12M,C12P,Y02E,Y02P

Abstract:
1. An apparatus for the conversion into biogas of fermentation stillage arising as a waste product of ethanol production in a bioethanol plant, the apparatus comprising: a first separation unit for the separation of the fermentation stillage into a thin fraction and a thick fraction, wherein the thin fraction has a lesser dry weight content than the thick fraction, a first biogas reactor downstream from the first separation unit, wherein the first biogas reactor is designed to ferment the thin fraction and is connected to the first separation unit via a pipe for transferring the thin fraction from the first separation unit to the first biogas reactor, a second biogas reactor downstream from the first separation unit, wherein the second biogas reactor is designed to ferment the thick fraction and is connected to the first separation unit via a pipe for transferring the thick fraction from the first separation unit to the second biogas reactor, a storage tank for collection of biogas produced in the first and second biogas reactors, a second separation unit, in the form of a nitrogen sink, to provide process water low in nitrogen or free from nitrogen from the reactor effluent from the first and second biogas reactors, and a return pipe from the second separation unit in the form of a nitrogen sink into the bioethanol plant, to return the effluent process water for dilution of the reactor content in the biogas reactors.