A model of microbial membrane bioreactor with convective flow through the membrane is presented in the paper. Permeability coefficients eta(i) in reference to microbial cells, substrates and possible reaction products as well as intensification coefficient W which is a hydrodynamic parameter very significant for this bioreactor type, were introduced. The latter coefficient is used to control the bioreactor operation. Advantages of the membrane bioreactor over the classical flow bioreactor are presented. A reduction of residence time, with other parameters kept constant, or an increase of the conversion degree which enables the growth of feed stream, is reached in the range of coefficient I < Psi < 3. A further increase of parameter Psi does not cause such a significant intensification any longer. Due to high efficiency of the membrane bioreactor operating in a broad range of inlet concentrations and at low outlet concentration, this type of a microbial bioreactor is particularly recommended in industrial wastewater biodegradation.