A sewage treatment plant is disclosed, in particular, a small sewage plant, comprising at least one activated sludge tank for effluent and/or at least one sedimentation tank for effluent, wherein the activated sludge tank and/or the sedimentation tank are filled with moulded bodies freely suspended in the effluent, characterised in having at least one filtration device for effluent purification with at least one ceramic based membrane for separation of microorganisms. A method for purification of effluent is further disclosed, comprising a biological purification of the effluent by microorganisms in at least one activated sludge tank and/or comprising a sedimentation of the effluent in at least one sedimentation tank, wherein the at least one activated sludge tank and/or the at least one sedimentation tank is filled with shaped bodies for the purification characterised in that the microorganisms in the effluent are separated by means of at least one ceramic based membrane.