Abstract: The invention relates to a bioreactor which comprises a closed housing with a housing wall and at least one chamber which is connected to the housing wall. The at least one chamber comprises a chamber inlet and outlet for respectively supplying and discharging material to and from the at least one chamber. The housing comprises a housing inlet for supplying material to the chamber inlet and a housing outlet for discharging treated material from the chamber outlet to the outside of the bioreactor. The bioreactor forms a closed volume in which a reactor pressure prevails in the bioreactor which is higher than the external pressure outside the bioreactor, in such a way that the bioreactor is self-supporting.