Abstract: The present invention relates to a method for preparing organic material for microbiological fermentations of municipal waste water sludge for reducing the waste water sludge and/or of cellulosic material for the production of biofuels, with at least one of the following steps: disintegrating and/or liquefying the organic and/or cellulosic material by using a jet pump and/or creating a supersonic shock zone in a jet pump the organic and/or cellulosic material is supplied to in order to disintegrate and/or liquefy the organic and/or cellulosic material and/or applying high pressure steam to an annular ring chamber enclosing a tube of a jet pump and directing the steam into the tube of the jet pump thereby sucking organic and/or cellulosic material into the tube and creating a supersonic shock zone in the jet pump in order to disintegrate and/or liquefy the organic and/or cellulosic material.