Filtration method and device

The invention relates to a filtration method having a filtration device with a process tank (1) into which a feed (2) for supplying a medium to be processed, in particular a fermentation broth to be filtered, empties, wherein at least one filtration arrangement (9) is arranged in the process tank (1) and wherein the process tank (1) has at least one drain and is designed such that the filtration of the medium to be filtered can be carried out with the retentate remaining in the process tank (1) until the retentate is drained after completion of the filtration, having the following process steps: a) the process tank (1) is filled with the medium to be filtered and a pre-defined trans-membrane pressure is created on the at least one membrane filtration arrangement (9); b) the medium, in particular the fermentation broth, in the process tank (1) is filtered by the membrane filtration arrangement (9) until a pre-defined limit value of solid material, in particular of biomass, is reached in the mass fraction.