Anaerobic digester - with concentric fermentation and settling tanks and plastic cover

摘要

The plastic cover is in the form of an inverted bell of flexible material, impervious to the fermentation gases and covering only the central decanting tank with its skirs immersed in the liquid. The outer fermentation tank is covered with a ring of trapezoidal, prefabricated concrete slabs sealed at their joints and to the shoulders in the outer and divider walls on which they rest so as to form a sealed, gas-tight lid. Gases from the central tank bleed via pipes into the top of the outer fermenting tank whence they are evacuated by a pipe. Reduced size required of plastic cover compared to parent patent 764.701 in which the plastic cover was over both tanks.