Method and installation for removing sulphur from the digestate and the biogas of a digester

Method for removing sulphur from the digestate and the biogas in a city and/or agricultural and/or industrial effluent digester, using a wet and/or a dry route, the digester (1) being made up of a closed vessel (2) in which a mass of products to be treated, that forms the digestate, undergoes anaerobic digestion with a volume of gas on top of the digestate from which the biogas is extracted, the digestate being drawn off at a point (5) of the digester then reinjected at another point (7). The digestate drawn off is made to follow: an upward first path (10) with injection of gaseous oxidizing agent at the bottom for aeration, the gaseous oxidizing agent and the digestate flowing concurrentwise; and a downward second path (12) under anaerobic conditions before returning to the digester, the excess gaseous oxidizing agent being removed in the top part (20) of at least one of the paths.