The invention relates to a method for treating biomass (2). Biomass (2) is fed to a pressurized prehydrolysis reactor unit (8) by means of a feeding system (5, 7), wherein by means of the feeding system (5, 7) the biomass (2) is compressed. A filtrate is squeezed out of the biomass (2) by means of the feeding system (5, 7), in particular by a first plug screw (5) or a second plug screw (7) of the feeding system (5, 7). The biomass (2) is then thermally treated in the pressurized prehydrolysis reactor unit (8), discharged from the pressurized prehydrolysis reactor unit (8) afterwards, diluted with the filtrate before or after the discharge, and treated with an enzyme subsequently.