NOVELTY - The method involves subjecting a digestate to anaerobic digestion with a volume of gas on top of the digestate. The digestate is drawn off at a point (5) of the digester and reinjected at another point (7) of the digester. The drawn off digestate is made to follow an upward path (10) during injection of a gaseous oxidizing agent at a bottom part of the digester. The drawn off digestate is made to follow a downward path (12) under anaerobic conditions before returning to the digester, where the excess gaseous oxidizing agent is removed in a top part (20) of the upward or downward path.    USE - Method for desulfurizing digestate and biogas in a city, agricultural and/or industrial effluent digester of a biogas generating station (claimed) e.g. waste water treatment station, a discharge treatment station and an agricultural product digestate treatment station, that is utilized for generating a biofuel and energy.    ADVANTAGE - The drawn off digestate is made to follow the upward path during injection of the gaseous oxidizing agent at the bottom part of the digester and the downward path under the anaerobic conditions before returning to the digester, where the excess gaseous oxidizing agent is removed in the top part of the upward or downward path, thus enabling complete dissolution of the oxidizing agent in the digestate, and hence enabling reduction of frequency of maintenance operations such as cleaning of walls, of the digester. The method enables desulfurization of the digestate and the biogas in a simple and economical manner.    DETAILED DESCRIPTION - The gaseous oxidizing agent is air or oxygen. An INDEPENDENT CLAIM is also included for a biogas generating station.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of an installation for desulfurizing a digestate and a biogas in a city, agricultural and/or industrial effluent digester.    Points of digester (5, 7)    Upward path (10)    Downward path (12)    Top part of upward or downward path (20)    Vent tube (21)