Patent ID: 7914675

Claim:
A process for the anaerobic purification of waste water in an anaerobic reactor, wherein anaerobic sludge is used to purify waste water and to produce biogas, which process comprises conditioning waste water in a compartment separate from the said reactor, wherein a) said compartment is connected to a hot water boiler by means of a line between the gas head of the boiler and said compartment; b) said line connecting the hot water boiler to the compartment ends underneath the waste water level in said compartment at such a level that a pressure of between 0.25 and 3 m of water column is maintained in the gas head of the boiler; c) wherein boiler steam generated in the gas head of the boiler enters said compartment through said line and heats the waste water; d) biogas generated in the reactor is burned in a gas burner, the hot gases obtained thereby are used for indirect heating of water in the hot water boiler, e) said boiler is further provided with a valve to let off steam in case the amount of biogas is in excess of the amount needed to heat the waste water; and introducing the waste water, which has been conditioned in a compartment separate from the said reactor in which it is purified, into the reactor; and wherein said anaerobic reactor and said boiler are placed adjacent in the same housing, with an insulating wall between them; and/or wherein the biogas, as produced, is indirectly heated, prior to the burning thereof, in said boiler; and/or wherein the total amount of biogas is fed to said gas burner and exhaust gases of the burner, after indirect heat exchange in said boiler, are vented to the atmosphere; and/or wherein said boiler is provided with a second burner, which is suitable for fuel gas or liquid fuel, to be used in case the production of biogas is too low to provide the required heating.