TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The reaction vessel is configured for providing an expanded or fluidized bed of the immobilized lipase preparation. The reaction vessel comprises: a vessel inlet port and a vessel outlet port, where the vessel inlet port is at a location lower than that the vessel outlet port; a stirring system for stirring the reaction medium and the immobilized lipase preparation within the reaction vessel; the immobilized lipase preparation, at least during operation of the processing system for the production of the fatty acid alkyl esters; the fatty acid source and the alcohol and an alcohol donor, at least during operation of the processing system for the production of the fatty acid alkyl esters; or a thermal regulation processing system configured for maintaining the reaction medium in the reaction vessel within a selected temperature range. The reaction medium comprises: at least one of an aqueous alkaline buffer solution and water, where the water is at least one of free water and mixed with a polyol or polyols, at least during operation of the processing system for the production of the fatty acid alkyl esters; or a mixture, the processing system comprises a pre-reaction vessel in selective fluid communication with the reaction vessel via the vessel inlet port, and the pre-reaction vessel is configured for premixing at least the fatty acid source and the alcohol and alcohol donor to form the mixture, and for selectively delivering the mixture to the reaction vessel at least during operation of the processing system for the production of the fatty acid alkyl esters. The processing system further comprises: a supply of fatty acid source in selective fluid communication with the pre-reaction vessel and configured for selectively delivering the fatty acid source to the pre-reaction vessel at least during the operation of the processing system, and alcohol source in selective fluid communication with the pre-reaction vessel and configured for selectively delivering the alcohol and an alcohol donor to the pre-reaction vessel at least during the operation of the processing system; at least one of an aqueous buffer source and a water source in selective fluid communication with the pre-reaction vessel and configured for selectively delivering the aqueous alkaline buffer solution and water, free or mixed with a polyol/polyols, to the pre-reaction vessel, to be included in the reaction mixture at least during the operation of the processing system; a retaining arrangement configured for retaining the immobilized lipase preparation within the reaction vessel at least during operation of the processing system; and a product separation vessel (160) in selective fluid communication with the reaction vessel, where the processing system is configured for selectively delivering a reaction mixture including reaction products from the reaction vessel to the product separation vessel, and the product separation vessel is configured for selectively separating a yield of the fatty acid alkyl esters from the reaction mixture delivered to it. The processing system is configured for: selectively delivering the fatty acid source and the alcohol and alcohol donor to the pre-reaction vessel in a continuous manner or in discrete batches at least during the operation of the processing system; selectively delivering the aqueous alkaline buffer solution and water, free or mixed with a polyol/polyols, to the pre-reaction vessel in a continuous manner or in discrete batches at least during the operation of the processing system; selectively and directly delivering to the reaction vessel the fatty acid source, the alcohol and alcohol donor and/or the aqueous alkaline buffer solution and water, free or mixed with a polyol/polyols; selectively dispensing the yield of fatty acid alkyl esters from the product separation vessel in a continuous manner or in discrete batches; increasing the yield of the fatty acid alkyl esters from the reaction mixture delivered to the product separation vessel; selectively rerouting the yield of the fatty acid alkyl esters to the reaction vessel to further increase the yield of the fatty acid alkyl esters from the reaction mixture subsequently delivered to the product separation vessel; selectively rerouting the yield of the fatty acid alkyl esters to at least one auxiliary reactor modules, where each of the auxiliary reactor module comprises an auxiliary reactor vessel (102) and an auxiliary product separation vessel, and the further increased yield of the fatty acid alkyl esters is selectively subsequently delivered via a respective the auxiliary product separation vessel; selectively outputting and rerouting a reaction mixture including the reaction products back to the reaction vessel for further processing in it for enhancing yield of the fatty acid alkyl esters; selectively outputting and rerouting a reaction mixture including the reaction products back to the reaction vessel and for selectively subsequently outputting and delivering a modified reaction mixture including reaction products to the product separation vessel, where the product separation vessel is configured for selectively separating a yield of the fatty acid alkyl esters from the reaction mixture delivered to it; rerouting the reaction mixture through the reaction vessel in a direction at least partially opposed to gravity; selectively outputting and rerouting a reaction mixture provided by each the auxiliary reaction vessel back to the respective the auxiliary reaction vessel for enhancing yield of the fatty acid alkyl esters; selectively outputting and rerouting a reaction mixture including the reaction products provided by the respective the auxiliary reaction vessel back to the respective the auxiliary reaction vessel and for selectively subsequently outputting and delivering a modified reaction mixture including reaction products from the respective the auxiliary reaction vessel to the respective the auxiliary product separation vessel, where the respective auxiliary product separation vessel is configured for selectively separating a yield of the fatty acid alkyl esters from the reaction mixture delivered to it; or passing the reaction products through each the auxiliary reaction vessel in a direction at least partially opposed to gravity. The pre-reaction vessel is configured for selectively delivering the mixture to the reaction vessel in a continuous manner or in discrete batches at least during the operation of the processing system. In the processing system retaining arrangement is at one or both of the reaction vessel outlet and the reaction vessel inlet. The product separation vessel comprises one of a centrifuge, coalescer and gravity separation processing system. The reaction vessel is configured for selectively delivering the reaction mixture to the product separation vessel in a continuous manner or in discrete batches at least during the operation of the processing system. The auxiliary reaction vessel is configured for reacting the yield of the fatty acid alkyl esters in the presence of an immobilized lipase preparation, where the immobilized lipase preparation comprises at least one lipase immobilized on a hydrophobic porous support and the processing system is configured for passing the reaction medium through the immobilized lipase preparation in the respective the auxiliary reaction vessel in a direction at least partially opposed to gravity.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The reaction provides reaction products including the fatty acid alkyl esters. The process further comprises: the step of selectively directly recirculating the reaction products to the immobilized lipase preparation; and the step of selectively separating fatty acid alkyl esters from the reaction products. In the recirculating step, the reaction products are passed through the immobilized lipase preparation in a direction at least partially opposed to gravity. The process comprises repeating the step of selectively directly recirculating reaction products of the reaction to the immobilized lipase preparation many times. In the process upon adding the aqueous alkaline buffer solution the pH of the reaction medium containing the oil feedstock is 5-11, respectively upon adding the water which is in the form of a water solution of at least one of dissolved salts and polyol/polyols the pH of the reaction medium containing the oil feedstock is 3-11. The alkaline buffer solution is added to the fatty acid source in a premixing stage or directly to the reaction medium. The reaction is carried out at 0-100 degrees C, preferably 20-30 degrees C. The process is conducted in the processing system. Preferred Components: The aqueous alkaline buffer solution and water is contained at a quantity of at least 0.01 wt.%, preferably 5 wt.% of the fatty acid source. The alcohol is a short-chain alcohol, preferably methanol or ethanol, or the alcohol is a medium-chain fatty alcohol (6-10C) or long-chain fatty alcohol (12-22C). The alcohol donor is a mono-alkyl ester, including methyl acetate or a di-alkyl carbonate, including di-methyl carbonate, serving also as a source for mild alkaline reagent in the reaction medium. The lipase is a lipase derived from any one Rhizomucor miehei, Pseudomonas sp. Rhizopus niveus, Mucor javanicus, Rhizopus oryzae, Aspergillus niger, Penicillium catnetnbertii, Alcaligenes sp. Acromobacter sp. Burkholderia sp., Thermomyces lanuginosus Chromobacterium viscosum, Candida antarctica B, Candida rugosa, Candida antarctica A, papaya seeds and pancreatin. The immobilized lipase is capable of catalyzing the esterification of free fatty acids to yield fatty acid alkyl esters and water as by-product, and the transesterification of triglycerides and partial glycerides to yield fatty acid alkyl esters and glycerol as by-product. The lipase preparation comprises at least two lipases which can be each separately immobilized on a hydrophobic support or co-immobilized on the same hydrophobic support, where the lipases possess identical or different regio-specificity or selectivity to fatty acyl groups. The support is any one of hydrophobic aliphatic polymer-based support and hydrophobic aromatic polymer-based support. The support is porous or non-porous inorganic support, which can be hydrophobic or is coated with hydrophobic organic material. The fatty acid source is plant oil, animal fat, algal oil, fish oil, waste oil and/or grease trap. The fatty acid source comprises free fatty acids, mono-, di- and/or tri-glycerides, at any ratio, in the absence or presence of other minor fatty acid derivatives including phospholipids and wax esters, more specifically the fatty acid source is unrefined, refined, bleached and/or deodorized. The alcohol is methanol and the resulting fatty acid esters are fatty acid methyl esters (fatty acid methyl esters-biodiesel).