VORRICHTUNG ZUR HERSTELLUNG VON BIOGAS

An apparatus and method for the recovery of gas evolved from fermentation is disclosed. The apparatus comprises a vessel containing the fermentation material, and a head slidably mounted on the vessel forming a substantially gas tight chamber therewith. Mounted on the head are a series of projections of various shapes which extend into the chamber. As the fermentation proceeds, the generation of gas causes the head to rise. When it has risen a sufficient amount, a gas outlet valve is opened and the gas is introduced into a collector. The reduction in gas pressure causes the head to drop. The movement of the head causes the projections to break through the scum layer at the surface of the fermentation broth, thereby enhancing the reaction. In a preferred form of the device, the projections are so formed as to urge the scum towards the discharge means, thereby breaking and removing the scum without the use of any additional energy. A method for using the apparatus is also disclosed.