US 12,338,477 B2
Recovery of methane from solid digestates
Aude Bertrandias, Paris (FR); Ulysse Bremond, Paris (FR); Jean-Philippe Steyer, Paris (FR); and Helene Carrere, Paris (FR)
Assigned to L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude, Paris (FR); and Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Paris (FR)
Filed by L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude, Paris (FR); and Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Paris (FR)
Filed on May 18, 2021, as Appl. No. 17/323,484.
Claims priority of application No. 2005137 (FR), filed on May 20, 2020.
Prior Publication US 2021/0363550 A1, Nov. 25, 2021
Int. Cl. C02F 1/00 (2023.01); C02F 11/04 (2006.01); C02F 11/12 (2019.01); C12M 1/00 (2006.01); C12M 1/107 (2006.01); C12P 5/02 (2006.01)
CPC C12P 5/023 (2013.01) [C02F 11/04 (2013.01); C02F 11/12 (2013.01); C12M 21/04 (2013.01); C12M 23/36 (2013.01); C12M 23/58 (2013.01)] 7 Claims
 
1. A process for producing biogas from a digestate obtained from a digester, wherein the biogas predominantly contains methane and CO2 and also contains in smaller proportions of water, nitrogen, hydrogen sulfide and oxygen than the proportions of methane and CO2, said process comprising the steps of:
a) introducing biomass into a digester and/or a post-digester;
b) anaerobic digestion in the digester and/or a post-digester;
c) producing a first stream of biogas and digestate;
d) separating the digestate into a solid digestate and a liquid digestate;
e) introducing the solid digestate into at least one closed tank in parallel;
f) anaerobic digesting the solid digestate in the closed tank with neither heating nor mixing; and
g) recovering the biogas at the closed tank outlet,
wherein the anaerobic digesting step is carried out with a step of inertizing of the tank with CO2 obtained from the anaerobic digesting the solid digestate,
wherein steps e) and f) employ at least two tanks in parallel,
wherein the amount of the biogas produced by the anaerobic digesting the solid digestate is measured at step f),
wherein the measured amount of the biogas produced by the anaerobic digesting the solid digestate is compared to a target value of the amount of the biogas, wherein the step of the anaerobic digesting the solid digestate is halted when the each measured amount of biogas produced by the anaerobic digesting the solid digestate is greater than the target value.