NOVELTY - Hydrolyzing and acidifying homogenized organic waste fed into a closed and gas tight reactor using natural enzymes released by bacteria under thermophilic conditions where water may be added to the reactor and the content of the reactor can be mixed, comprises subjecting during hydrolysis and acidification an adequate part of a suspension formed in the reactor to a separation step by isolating a permeate comprising an aqueous solution of soluble carbon, volatile fatty acids (VFA) and valuable nutrients from an organic slurry comprising an aqueous solution of insoluble organic solids.    USE - The method or apparatus is useful for hydrolyzing and acidifying homogenized organic waste fed into closed and gas tight reactor using natural enzymes released by bacteria under thermophilic conditions where water may be added to the reactor and the content of the reactor can be mixed (claimed).    ADVANTAGE - During hydrolysis and acidification, spent solids and permeate comprising soluble carbon, VFA and valuable nutrients can be removed from the organic slurry thus allowing a higher load of the reactor at lower capital and operating costs compared to reactors used for traditional hydrolysis and acidification. The recirculation of un-hydrolyzed organic matter rich in thermophilic bacteria to the reactor after separation speeds up hydrolysis of the organic slurry.    DETAILED DESCRIPTION - Hydrolyzing and acidifying homogenized organic waste fed into a closed and gas tight reactor using natural enzymes released by bacteria under thermophilic conditions where water may be added to the reactor and the content of the reactor can be mixed, comprises subjecting during hydrolysis and acidification an adequate part of a suspension formed in the reactor to: (i) a separation step by isolating a permeate comprising an aqueous solution of soluble carbon, volatile fatty acids (VFA) and valuable nutrients from an organic slurry comprising an aqueous solution of insoluble organic solids rich in thermophilic bacteria and non-hydrolyzed organic solids, and the remaining part of soluble carbon, VFA and valuable nutrients not isolated in the permeate to: (ii) a recirculation step re-feeding the organic slurry into the reactor for further hydrolysis and acidification and (iii) a release step discharging the permeate of step (i) from hydrolysis and acidification for further use and to: (iv) a removal step optionally discharging spent solids contained in the suspension from the reactor, while: (v) optionally adjusting pressure in the reactor to ensure a constant equilibrium; (vi) optionally adding air or oxygen to the reactor to ensure micro-aerophilic conditions; (vii) optionally adjusting pH to a value between 4 and 7; (viii) optionally maintaining temperature between 45 and 70 degrees C; and (ix) optionally maintaining redox at a value in the range of (-500) mV to +200 mV. An INDEPENDENT CLAIM is an apparatus for carrying out the method comprising at least one closed and gas tight reactor having openings at least for feeding organic waste and for adding water and a mixer for stirring the content, characterized by having at least one cycle loop with the following attached elements: (i) at least one separation means to isolate a permeate comprising an aqueous solution of soluble carbon, VFA and valuable nutrients from an organic slurry comprising an aqueous solution of insoluble organic solids rich in thermophilic bacteria and non-hydrolyzed organic solids, and the remaining part of soluble carbon, VFA and valuable nutrients not isolated in the permeate and optionally to remove the permeate from the reactor; (ii) at least one removal means to take samples of organic sludge from the reactor, measure the concentration of fixed solids and spent solids in the samples and optionally remove spent solids from the reactor; (iii) at least one aspiration means for adding air and/or oxygen to the reactor to ensure micro- aerophilic conditions; (iv) at least one pressure adjustment means to regulate headspace pressure in the reactor, having a withdrawal cycle and a filling cycle; (v) at least one means for heating and cooling to control temperature in the reactor; and (vi) optionally at least one pH adjustment means (9) to regulate the pH value in the reactor.