TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: Hydrolyzing and acidifying homogenized organic waste fed into closed and gas tight reactor further comprises: (a) using as organic waste wastewater sludge, food processing waste, commercial waste, agricultural waste, organic municipal solid waste, animal manure, industrial by-products like Category 2 and Category 3 waste according to EU regulation NO. 1069/2009, or its mixture, preferably organic waste with a high content of carbohydrates, lipids and proteins, and by feeding the waste continuously, semi-continuously or discontinuously; (b) separating the permeate from the organic slurry through filtration; (c) adjusting the pressure by a gas balloon which intakes the gas formed during hydrolysis and feeds the gas into the reactor when pressure drops in the reactor due to removal of the permeate and/or spent solids; (d) measuring the concentration of fixed solids and spent solids in the hydrolyzed organic waste continuously and removing spent solids from the hydrolysis and acidification process when the concentration of fixed solids reaches a preset value, preferable 40 to 50 m/m%; (e) discharging the permeate and feeding additional homogenized organic waste continuously, semi-continuously or discontinuously at a 1:1 ratio; (f) adjusting the pH value to 6.0 to 6.8 by addition of acid when the pH value rises above 6.8 or by addition of alkali when the pH value drops below 6; (g) adjusting the temperature to 60-65 degrees C; and (h) adjusting the redox value to (-300) mV to (-200) mV. Preferred Apparatus: In the apparatus, the separation means comprises at least one removal opening to release the permeate, at least one plastic or porous ceramic filter with a pore size of 0,001 to 10 mu m, preferably 0.1 mu m, and at least one passage opening for entering and/or circulating the suspension from and back to the reactor. The removal opening comprises a release pipe with a valve attached to adjust discharge of the permeate. The porous ceramic filter comprises pipes or flat plates. Separation means comprises membrane as filter. Removal means comprises a valve mounted to a removal pipe attached to the reactor or to a recirculation pipe attached to the reactor. Aspiration means comprises a self-aspirating injector with a valve mounted to an aspiration pipe attached to the reactor. Pressure adjustment means is a gas balloon mounted to an adjustment pipe attached to the reactor. EXAMPLE - No example given.