An apparatus for treating organic mass. The apparatus comprises a treatment chamber and agitation means provided in the chamber to agitate the organic mass. The agitation means comprises a rotatable shaft extending through the chamber, a plurality of agitator arms extending from the shaft, and a paddle connected to each agitator arm. The paddle is arranged to make a first angle with respect to the longitudinal axis of the agitator arm and a second angle with respect to the longitudinal axis of the shaft. There is also provided a system for recycling ammonia generated from the treated organic mass by the apparatus.
