Patent ID: 9359240
Filing Date: 2016-06-07
CPC Classification: C02F,C12M,Y02E,Y02W

Claim Text:
1. A method for desulfuration of a digestate and a biogas in a digester for urban and/or agricultural and/or industrial effluents, by wet and/or dry route, the digester comprising a chamber which is closed at the top and in which anaerobic digestion of a mass of products to be treated takes place, forming the digestate, with a gas space above the digestate, from which the biogas is withdrawn, the digester comprising at least one external digestate recirculation loop, wherein: a digestate withdrawal point is situated in the lower part of the digester, and the digestate is reinjected at a point at a liquid level higher than the withdrawal point, at least one point of the digestate recirculation loop, a gaseous or liquid oxidant is injected, the injection conditions being as follows: a circulation rate of the digestate in the loop is sufficient to prevent the deposition of sulfur on the walls of the lines in the recirculation loop, a contact time between the injected oxidant and the recirculated digestate, from the point of injection of the oxidant to a point of reintroduction of the digestate in the chamber, is sufficient for all of the oxidant to be dissolved in a liquid phase of the digestate, the amount of oxygen in the oxidant injected into the digestate is low enough to prevent a presence of oxygen in the biogas but high enough to remove hydrogen sulfide from the biogas, a sulfur produced remaining in the form of particles which are dispersed in the digestate and being removed together with the digestate.