NOVELTY - Production of liquid biofuel product from vegetable or animal oil or fat feedstock comprising greater than or equal to 5 wt.%, preferably greater than or equal to 25 wt.% free fatty acids (FFA) involves performing acid catalyzed FFA esterification, performing base catalyzed trans-esterification of glycerides present in feedstock material, and performing purification and/or recycling and recovery of ingredients or reaction products. In 1st step (a), esterification of FFA is carried out in 1st biofuel reactor (1) equipped with binary fluid pneumatic nozzles (3, 5).    USE - Production of liquid biofuel product from vegetable or animal oil or fat feedstock for combustion engines.    ADVANTAGE - The method efficiently and safely converts vegetable or animal oil or fat feedstock into premium quality biodiesel. Risk of explosions is reduced.    DETAILED DESCRIPTION - Production of liquid biofuel product from vegetable or animal oil or fat feedstock comprising greater than or equal to 5 wt.%, preferably greater than or equal to 25 wt.% free fatty acids (FFA) involves performing acid catalyzed FFA esterification, performing base catalyzed trans-esterification of glycerides present in feedstock material, and performing purification and/or recycling and recovery of ingredients or reaction products. In 1st step (a), esterification of FFA is carried out in 1st biofuel reactor (1) equipped with binary fluid pneumatic nozzles (3, 5) utilizing inert gas as carrier gas for generating and feeding aerosols (7) of liquid FFA-rich oil or fat component and of alcohol component into head space of the reactor, the alcohol component comprising short chain (1-5 carbon) alcohol optionally together with catalyst. Esterification reaction is allowed to take place to yield 1st reaction mixture (8). In 2nd step (b), phase separation of 1st reaction mixture is carried out to yield lipidic light phase (9) comprising fatty acid alkyl esters (FAAE) and unreacted glycerides, and heavy phase (10) comprising excess alcohol, water, and optionally catalyst in which phase separation of 1st reaction mixture is carried out in bottom space inside the 1st reactor by using integrated phase separator device (11) comprising greater than or equal to 1 demister or coalescer unit (13). An INDEPENDENT CLAIM is included for apparatus for carrying out production of liquid biofuel product comprising 1st biofuel reactor having reaction chamber (4) equipped with greater than or equal to 2 atomizer devices (2, 6), each one containing greater than or equal to 1 binary fluid pneumatic nozzles, for generating and feeding aerosols of both FFA-rich fat or oil component and alcohol component into head space of 1st reactor for carrying out esterification reaction of FFAs to yield 1st reaction mixture, and phase separation unit integrated in 1st biofuel reactor for separating 1st reaction mixture into light phase and heavy phase in which phase separation unit comprises hollow tubular body (12) arranged in horizontal direction relative to vertically positioned reaction chamber of 1st reactor, hollow tubular body extends from inside the 1st reactor to outside and has 1st open end located inside the reactor for receiving reaction mixture to be separated and 2nd closed end located outside the reactor, outside part of tubular body has outlet (14) for draining light phase and another outlet (15) for draining heavy phase, and inside part of tubular body further contains greater than or equal to 1 demister or coalescer device arranged inside its hollow body and close to its 1st open end.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of a combined esterification or trans-esterification reactor plus integrated phase separator.    1st biofuel reactor (1)    Atomizer (2)    Nozzle (3)    Reaction chamber (4)    Nozzle (5)    Atomizer (6)    Aerosols (7)    1st reaction mixture (8)    Light phase (9)    Heavy phase (10)    Phase separation unit (11)    Hollow tubular body (12)    Demister or coalescer device (13)    Outlets (14, 15)