Patent ID: 7056437

Claim:
A method of reducing or avoiding the formation of bulking sludge, floating sludge and/or foam, wherein filamentatious and flocculating microorganism-bearing effluent, sludge or organic substrates used in biogas installations are treated, characterised in that the effluent, sludge or organic substrates is or are guided in a conduit ( 2 , 4 ) and through at least one constriction ( 3 ) arranged in the conduit ( 2 , 4 ) and is or are subjected to a shear loading which is sufficient to reduce the relative ratio of the number of filamentous microorganisms in relation to flocculating microorganisms, wherein the shear loading is produced by a turbulent flow in the conduit, and wherein the flow speed of the effluent, the sludge or the organic substrates is increased on passing through the constriction ( 3 ) of the conduit ( 2 , 4 ) under a reducing pressure, wherein subsequently cavitation is produced in the effluent, in the sludge or in the organic subtrates.