Abstract: A method for waste water (1) treatment comprising the steps of: (a) combining waste water (1) with activated sludge (4) under anaerobic conditions; (b) transferring the products of step (a) to a container (B); (c) aerating the contents of the container (B); (d) allowing the contents of the container to settle and separate into an effluent layer (3) and an activated sludge layer; (e) decanting at least some of the treated effluent (3) and (f) recycling at least a proportion of the activated sludge (4) from step (d) to provide the sludge of step (a).