An apparatus and method for semi-permeable membrane based blood filtrationfeaturing controlled filtrate to non-filtrate separation ratio, self-regulating pressureintensification and energy recovery means and wherein basic embodiments canfunctionwithout the need for valves or any other control means. These capabilities areprovided forby a cooperating, positive displacement pump and motor set based apparatuswherein thegreater volumetric displacement of an upstream hydraulic pump cannot be fullytaken upby a lesser volumetric displacement downstream hydraulic motor as they operatesynchronously within the same series circuit. This causes pressureintensification withinthe fluid circuit located between the pump and motor such that a volume offluid essentiallyequal to the pump to motor volumetric displacement differential is compelledto flow out ofthe pressurized circuit by passing through or permeating the semi-permeablemembranelocated within it.
