NOVELTY - Producing biodiesel and glycerin comprises: filtering a biodiesel feedstock (303) to provide a filtrate; distilling the dried filtrate to provide a distillate; distilling the distillate to provide a subsequent distillate; repeating the distillation step to obtain a final distillate; contacting the transesterification reaction product with methanol and a solid heterogeneous transesterification catalyst to provide a subsequent transesterification reaction product comprising biodiesel, methanol, water, glycerin and optionally triglycerides; and separating the methanol and water via distillation.    USE - The method is useful for producing biodiesel and glycerin (claimed).    ADVANTAGE - The method produces high grade biodiesel and glycerin without introducing water, toxic mineral acid (including phosphoric acid, sulfuric acid, hydrochloric acid and/or citric acid) and toxic waste by reusing the reagent in a safe and renewable manner thus reducing the operating cost and time, energy consumption and carbon footprint.    DETAILED DESCRIPTION - Producing biodiesel and glycerin comprises (a) filtering a biodiesel feedstock (303) to separate from the feedstock solid particles having a diameter up to 2 microns, to provide a filtrate and a retentate, (b) separating water from the filtrate to provide a dried filtrate, (c) distilling (320) the dried filtrate to provide a distillate and a residue, (d) distilling the distillate to provide a subsequent distillate and optionally a subsequent residue, (e) repeating at least one of steps (c) and (d), one or more times, by distilling the subsequent distillate, to obtain a final distillate, (f) passing the final distillate through an ion exchange resin, (g) contacting methanol, a solid heterogeneous esterification catalyst immobilized on a solid support, and the final distillate, where the contacting is carried out under conditions suitable to provide an esterification reaction product comprising biodiesel, methanol, water, and optionally free fatty acids, (h) separating water and methanol from the esterification reaction product, (i) contacting the esterification reaction product with methanol and a solid heterogeneous esterification catalyst immobilized on a solid support, where the contacting is carried out under conditions suitable to provide a subsequent esterification reaction product comprising biodiesel, methanol, water and optionally free fatty acids, and the methanol separated from the one or more esterification reaction products is purified to a purity of at least 99.9 wt.%, and the methanol is employed in a subsequent esterification and/or transesterification, (j) contacting methanol, a solid heterogeneous transesterification catalyst immobilized on a solid support and the esterification reaction product at a temperature of less than 102 degrees F (38.89 degrees C), where the contacting is carried out under conditions suitable to provide a biodiesel, methanol, water, glycerin and optionally triglycerides, (k) separating water, glycerin and methanol from the transesterification reaction product, (l) contacting the transesterification reaction product with methanol and a solid heterogeneous transesterification catalyst immobilized on a solid support, where the contacting is carried out under conditions suitable to provide a subsequent transesterification reaction product comprising biodiesel, methanol, water, glycerin and optionally triglycerides, and (m) separating, via distillation, the methanol and water from the transesterification reaction product, to provide the biodiesel and glycerin, where the methanol that is separated from the one or more transesterification reaction products is purified to a purity of at least 99.9 wt.%, and is employed in a subsequent esterification and/or transesterification.    DESCRIPTION OF DRAWING(S) - The figure shows a process flow diagram for the transesterification of triglycerides.    Biodiesel feedstock (303)    Transesterification conditions (306)    Reaction product (315)    Distilling (320)    Purified biodiesel. (331)