Abstract: There is disclosed a fermentation device having a peripherally extending wall, a gas-impermeable cover extending over the surface of the device, and attached at its peripheral edge to a top part of the wall, and a gas collection conduit extending for at least part of the periphery of the device within the wall. This device may be used for wastewater treatment enclosures.

Abstract: There is disclosed a fermentation device having a peripherally extending wall, a gas-impermeable cover extending over the surface of the device, and attached at its peripheral edge to a top part of the wall, and a gas collection conduit extending for at least part of the periphery of the device within the wall. This device may be used for wastewater treatment enclosures.

Abstract: A fermentation pond has a cover and gas-collection system that includes a gas-impermeable membrane resistant to the elements and resistant to chemical deterioration by both the contents of the pond and any biogas generated by fermentation in the pond. The membrane overlies the full surface of the pond. A biogas collection conduit is positioned at the surface of the pond and under the membrane, and weights are located so as to urge the membrane downwardly along lines separated from each other so as to define between the lines a plurality of channels along which biogas can pass to the collection conduit.