TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The process further involves removing glycerol and unreacted alcohol from the second intermediate reacted mixture to form a purified second intermediate reacted mixture; adding additional non-recycled alcohol and additional non-recycled catalyst to the purified second intermediate reacted mixture; recycling the unreacted alcohol, glycerol and fatty acid alkyl esters to the high-shear reactor; and removing unreacted alcohol, glycerol and fatty acid alkyl esters from the crude biodiesel reacted mixture to form a purified biodiesel product. In the process, the high-shear reactor is a cavitation reactor operating at a shear rate of greater than 8000 s-1. The cavitation reactor is selected from rotor-rotor and rotor-stator mixer, homogenizer, microfluidizer, hydrodynamic or ultrasonic cavitation device, static mixer, orifice plate, perforated plate, nozzle, venturi eductor or jet mixer. The low-shear and the second low-shear reactor are operating at a shear rate of less than 1000 s-1. The low-shear reactor and the second low-shear reactor are selected from the group consisting of a batch mixer, agitator, rotor-stator, static mixer or tank equipped with a centrifugal pump recirculation loop. The ratio of catalyst to triglyceride feedstock reacted in the second low-shear reactor is 0.3-0.7 by weight. The ratio of catalyst to triglyceride feedstock reacted in the second low-shear reactor is less than 0.8 by weight. The alcohol reacted in the second low-shear reactor is 20-80 wt.% of the additional non-recycled alcohol. The catalyst reacted in the second low-shear reactor is 20-100 wt.% of the additional non-recycled catalyst. The recycling at least 70% of the glycerol and the unreacted alcohol recovered from the crude biodiesel reacted mixture to the high-shear reactor. The glycerol is removed from the crude biodiesel reacted mixture by a centrifuge, hydrocyclone or decanter. The alcohol reacted in the high-shear reactor is 20-80 wt.% of non-recycled alcohol. The catalyst reacted in the high-shear reactor is greater than 0-80 wt.% of non-recycled catalyst. The ratio of catalyst to triglyceride feedstock reacted in the high-shear reactor is 1.2-1.8 by weight. EXAMPLE - No suitable example given.