Anaerobic fermentor

Claim 1

An anaerobic fermentor comprising (i) a container vessel divided into at least two compartments each having a floor, a roof, and means for dividing the compartment into superposed zones and permitting upward fluid passage between the zones, said dividing and upward fluid passage means comprising a layer of liquid-pervious packing material disposed horizontally across the compartment at a position intermediate the roof and the floor with its lower surface upwardly spaced from the floor to define a fermentation zone therebetween and its upper surface downwardly spaced from the roof; (ii) liquid conduit means connecting successive compartments in series and providing downward liquid flow from the space between the roof and packing layer of one compartment to the space between the floor and packing layer of a succeeding compartment; (iii) means for introducing liquid to be treated into the space between the packing layer and the floor of the first of the successive compartments; (iv) means for removing treated liquid from the space between the packing layer and roof of the last of the successive compartments; (v) means provided in at least one fermentation zone for discharging solids from the fermentor; and (vi) means provided in each compartment between the upper surface of the packing layer and the roof of the compartment for discharging gas.