A mathematical model of the active transport of a negatively charged, small molecule through a reversed bienzyme porous membrane separating two compartments, recently presented, was analyzed. This model involved 13 identified parameters. The main parameters were studied both in terms of their impact on the final substrate surconcentration ratio (SR) and on the final product pollution level (PL) expected in a receiving compartment. Our analysis demonstrates that, with the topography involved, the active transport of a given negatively charged, small molecule only occurs provided that the three key factors act together and simultaneously : (i) bound reversed enzyme activities must exist at the pore entrance/exit; (ii) the first enzyme of the reactive sequence involved acts in an unstirred layer facing the feed compartment; (iii) the negatively charged molecules to be transported must be repelled by the negative charges on the membrane. Furthermore, our analysis permitted us to differentiate between the two different roles played by the two unstirred layers. It was found that the unstirred layer facing the feed chamber governs the substrate SR expected in the opposite receiving chamber, while the unstirred layer facing the receiving chamber plays a role only on the kinetic behavior of this active transport-like phenomenon. Besides the new Light brought on biological transport systems, this study may be of great interest for the improvement of the performances of a bioreactor/separator device.