TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The glycerides are formed by converting fatty acid in feedstock. The feedstock is conditioned by removing solids, and converted to glycerides. The fatty acid alkyl ester stream is separated by reactive distillation or gravimetrically into glyceride rich stream and fatty acid alkyl esters rich stream. Preferred Method: Manufacture of biodiesel from glycerides involves reacting glycerides with at least alcohol to form transesterficated effluent stream of fatty acid ester and glycerin, separating the transesterficated effluent stream of fatty acid ester rich stream and glycerin rich stream, introducing an organic acid to transesterficated effluent stream, fatty acid ester rich stream and/or glycerin rich stream and recovering. Preferred Composition: The glycerides are formed by mixing feedstock and glycerin at high temperature in absence of catalyst. The glycerides react with at least alcohol to form fatty acid alkyl ester stream in presence of alkali catalyst. The fatty acid alkyl ester stream contains glycerin and fatty acid alkyl esters. The organic acid is introduced to glycerin rich stream to obtain purified glycerin rich stream. The organic acid is weak organic acid chosen from group containing acetic acid, formic acid and/or propionic acid. The alcohol is 1-5C alcohol. The 1-5C alcohol is methanol. The alkali catalyst is chosen from group containing sodium hydroxide and/or potassium hydroxide. EXAMPLE - Rendered yellow grease containing free fatty acid (in wt.%) (20), moisture (2), and unsaponifiables (MIU) were added and reacted. Glycerin was added and heated at 210degreesC for 2.5 hours to obtain glycerides (85). Glycerides were cooled to 50degreesC and solution of potassium hydroxide in methanol was added at a rate of 1.1 lbs/min. Potassium hydroxide catalyst was added, reacted and soaps are converted to free fatty acids and potassium hydroxide was neutralized. Monobasic potassium phosphate precipitate was filtered and adjusted to pH of 7.5 with potassium hydroxide to obtain glycerin (95 wt.%). The obtained glycerin was recycled to obtain biodiesel.