TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The system comprises a heat exchanger running in counter-current principle for exchanging heat. The thermal decomposition reactor has a stirring device, preferably a stirring tool, for continuously stirring lignocellulosic biomass and/or for maintenance of the homogeneous mass transport. A cooler is provided downstream of heat exchanger, to adjust the thermally treated biomass or the thermally treated effluent to a suitable temperature such that the temperature of the anaerobic fermentation is maintained in a specific range. At least one aerobic reactor optionally with a phase separator is provided after a damper or the mixer and/or an anaerobic digester, to treat lignocellulosic material with fungi such that lignin is decomposed and/or divided at least partially. A plant for the separation of substances e.g. a reverse osmosis membrane or an evaporator or crystallization device is provided after at least one phase separator to clean at least partially recovered process water of unnecessary materials.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The method comprises: a further step (a1) which is carried out after the step (a) and before the step (b) in which an anaerobic fermentation of the mixed lignocellulosic biomass is performed by using the microorganisms and recovering the biogas produced; and (a2) before carrying out the step (b), which comprises subjecting the lignocellulosic biomass obtained in the step (a) or lignocellulosic biomass obtained in the step (b), to a first anaerobic fermentation in a heat exchanger (5) operated in counter current principle and thermally treating lignocellulosic biomass. The method comprises preheating of the lignocellulosic biomass obtained in step (a) or (a1) to a temperature of 110-180 degrees C, preferably 130-160 degrees C. The lignocellulosic biomass is crushed to average particle size of less than 200 mm, preferably less than 20 mm prior to the mixing. The anaerobic fermentation is carried out together with: adjusting the sodium content to 100-5000mg/l, by dosing sodium compounds; and adjusting ammonium content to 100-2000 mg/l, by dosing ammonium compounds. The stream is subjected to sequence of at least a fermentation, and a phase separation at least in part, while a liquid phase is obtained in the form of process water which is at least partly used in the biogas production process, preferably for mixing of lignocellulosic biomass, and is recycled such that there is supply of fresh water in the biogas production process and/or mixing is at least substantially reduced or completely eliminated. The stream is subjected to phase separation after completion of fermentation to obtain a solids phase as an organic fertilizer such that the organic fertilizer is used for sustainable management by ensuring the humus reproduction and/or closing the nutrient cycle of agricultural crops. The parts of the lignocellulosic flow and/or parts of the solids-rich phase is subjected to at least proportional phase separation of the lignocellulosic flow preferably to pasteurization by a biological treatment with lignin-degrading fungi, to assist for biogas production after re-feeding in an anaerobic fermentation and/or, to obtain a liquid phase in the form of process water for recycling to the biogas production process, for mixing of lignocellulosic biomass after subsequent phase separation. The lignocellulosic biomass is subjected to biological treatment with enzymes or fungi, during and/or after mixing with water in the form of process water and/or using steam under the presence of free water, such that cellulose and/or hemicellulose components are provided in a subsequent anaerobic fermentation. An additional organic substance, preferably dung or manure is added to the lignocellulosic biomass, where the addition of the additional organic substances is carried out before or during mixing of the lignocellulosic biomass in step (a) and/or before or during the anaerobic fermentation. The mixing of lignocellulosic biomass is carried out at a temperature of 60-100 degrees C, preferably 70-85 degrees C for a period of 1-30 minutes, preferably 5-15 minutes. EXAMPLE - No suitable example given.