NOVELTY - Producing fatty acid alkyl esters by transesterification of fats or oils with alkyl alcohols, comprises mixing the fats or oils and alkyl alcohols, and a catalyst in a mixing reactor (2, 5) in at least one reaction steps (1, 4); separating the resulting mixture into a low, ester-rich phase and a heavy glycerin-rich phase; separating fatty acid alkyl ester from the low, ester-rich phase; and contacting the fat or oil and/or raw alkyl ester produced by transesterification and/or biodiesel end products obtained after the separation of byproducts, with a strong organic or strong inorganic acids.    USE - The process is useful for producing fatty acid alkyl esters. The agent is useful in the production of fatty acid from fats or oils (claimed).    ADVANTAGE - The process avoids the solid deposition in the production plant and in the end products during the production of biodiesel.    DETAILED DESCRIPTION - Producing fatty acid alkyl esters by transesterification of fats or oils with alkyl alcohols, comprises mixing the fats or oils and alkyl alcohols, and a catalyst in a mixing reactor (2, 5) in at least one reaction steps (1, 4); separating the resulting mixture into a low, ester-rich phase and a heavy glycerin-rich phase in a separator (3, 6, 21); separating fatty acid alkyl ester from the low, ester-rich phase; and contacting the fat or oil and/or the raw alkyl ester produced by transesterification and/or biodiesel end products obtained after the separation of byproducts, with a strong organic or strong inorganic acids. INDEPENDENT CLAIMS are included for:    (1) agents to avoid or eliminate sterol glycoside containing precipitates in the production of fatty acid alkyl esters, where the agent is a strong organic or strong inorganic acid; and    (2) a plant for the production of fatty acid alkyl esters, comprising, in at least one reaction steps, a mixing reactor for mixing the fats or oils with the alkyl alcohols and a separator in which the mixture is separated into a low, ester-rich phase and a heavy, glycerin-rich phase, and a separator (21) for separating fatty acid alkyl ester from the low, ester-rich phase, and a mixing device (26, 27, 28) for mixing the supplied fats or oil and/or raw alkyl ester produced by transesterification and/or the biodiesel end products obtained after the removal of byproducts with the agent, as ingredients.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of a plant for carrying out the process for producing fatty acid alkyl ester (Drawing includes non-English language text).    Reaction steps (1, 4)    Mixing reactors (2, 5)    Separator (3, 6, 21)    Drying device (25)    Mixing device (26, 27, 28)    Washing device (29, 30, 31)    Two drying devices. (32)