Abstract: The invention relates to a method and an apparatus for hydrolyzing and acidifying homogenized organic waste fed into a closed and gas tight reactor using enzymatic bacteria under thermophilic conditions where water may be added to said reactor and the content of the reactor can be mixed and subjecting during hydrolysis and acidification an adequate part of a suspension formed in the reactor to—i. a separation step isolating—a permeate comprising an aqueous solution of soluble carbon, volatile fatty acids (VFA) and valuable nutrients, —an organic slurry comprising an aqueous solution of insoluble organic solids rich in enzymatic thermophilic bacteria and non-hydrolyzed organic solids, and the remaining part of soluble carbon, VFA and valuable nutrients, thereafter to—ii. a recirculation step re-feeding said organic slurry into the reactor for further hydrolysis and acidification.