Abstract: Apparatus for anaerobic digestion of organic waste material comprises a container divided into three interconnected chambers situated one below the other, the upper chamber being an inlet chamber, the lower chamber being a mixing chamber and the intermediate chamber being a settlement chamber, the inlet chamber having an inlet for material to be treated, a duct from the inlet chamber down into the mixing chamber, at least one transfer duct from the mixing chamber up into the settlement chamber, the duct or ducts extending below the upper extent of that mixing chamber, a gas collection zone at the upper extent of the mixing chamber, at least one recirculation duct from the base of the settlement chamber down into the mixing chamber, a further gas collection zone in the upper extent of the settlement chamber and an outlet from the settlement chamber situated below the further gas collection zone.

Abstract: An apparatus for the anaerobic digestion of natural organic waste comprises a feed tank, a digester and an outlet tank. There is further provided feed means which feeds waste to be digested from the feed tank to the digester at an adjustable continuous rate. A gas pump may be used to recirculate from the top of the digester through a diffuser to the bottom of the digester. A suitable gas pump comprises a container partially filled with liquid so as to provide a space above the liquid surface and within the container sealed by the liquid from the exterior of the container, pumping means being provided in the said space.