NOVELTY - Producing a fuel (preferably a liquid fuel) or another organic product from a carbonaceous feedstock, comprises: (a) gasifying the feedstock in a first reactor which is a gasifier (1); (b) downstream of the gasifier, fermenting synthesis gas product formed during gasification step, by means of microorganisms, water and nutrients in a second reactor which is fermenter (2); (c) collecting, downstream of the fermentor, the microorganisms and water; (d) injecting at least a portion of the microorganisms and optionally at least a portion of the water recovered in input (10) of the gasifier.    USE - The method is useful for: producing a fuel (preferably a liquid fuel) or another organic product from a carbonaceous feedstock, where the organic product obtained is acetate, formate, butyrate, ethanol, butanol, acetone or 2,3-butanediol; and producing methanol or ethanol from plastic residue (all claimed).    ADVANTAGE - The method: is carried out at lower temperature and pressure; utilizes the microorganisms as biocatalysts allows to tolerate a greater extent of impurities present in the synthesis gas product and a wider range hydrogen/carbon monoxide ratios; and utilizes the apparatus which reprocesses the fermentation waste in cost effective manner, retreats the water after the fermentation in the gasification step, and thus avoids the need gasifying agent, increases the material efficiency, and allows for adjusting desire water and carbon material ratio.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for apparatus for continuously producing the fuel or another organic product from the carbonaceous feedstock, comprising a gasifier, a fermenter in downstream of the gasifier, having in it microorganisms, water and nutrients for carrying out the fermentation of synthesis gas produced by the gasifier, retrieval means (3) for at least a portion of the microorganisms and water, downstream of the fermenter, recovery means being connected to the input of the gasifier so as to inject at least a portion of microorganisms and optionally at least part of the recovered water.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the apparatus.    Gasifier (1)    Fermenter (2)    Retrieval means (3)    Distillation device (4)    Input of the gasifier (10)