NOVELTY - Method for generating biogas from an anaerobic fermentation of processed organic material, involves subjecting the organic material to hydrolysis, subjecting the pre-incubated organic material to lime pressure cooking process to obtain ammonia fluid, absorbing and condensing the ammonia fluids, mixing pre-incubated and lime pressure cooked organic material in a mixing tank, optionally mixing the lime pressure cooked organic material with further organic material, fermenting the mixture under anaerobic conditions and collecting the biogas.    USE - The method is useful for generating biogas from anaerobic fermentation of processed organic material comprising deep litter or manure from animals chosen from cattle, pigs and poultry (all claimed).    ADVANTAGE - The method generates biogas and renewable energy in large quantities. The method enables conversion of energy potential to a readily usable energy source, and improves removal of organic bound nitrogen from different biomass and ammonia nitrogen from anaerobic digestion process as anaerobic fermentation is sensitive to high levels of ammonia. The biogas plant hydrolyzes organic material before anaerobic fermentation and biogas production.    DETAILED DESCRIPTION - Method for generating biogas from an anaerobic fermentation of processed organic material comprising solid and liquid portions, involves (a) transferring a first organic material comprising one or more sources of nitrogen to a pre-incubation tank and subjecting the organic material to hydrolysis by chemical and/or biological unit, where the hydrolysis results in the conversion of organic nitrogen present in the organic material to inorganic nitrogen, (b) transferring the pre-incubated first organic material to a lime pressure cooker and subjecting the first pre-incubated organic material to lime pressure cooking process, where the lime-pressure cooking results in a further hydrolysis of first organic material, and the lime pressure cooking step results in the formation of ammonia fluids, (c) transferring the ammonia fluids formed in the lime pressure cooker to an absorption unit, and absorbing and condensing the ammonia fluids in absorption unit, (d) transferring pre-incubated and lime pressure cooked organic material from the lime pressure cooker to a mixing tank to adjust pH of the lime pressure cooked material, and optionally mixing in the mixing tank, the lime pressure cooked organic material with a further organic material, where the organic material is preferably not been subjected to lime pressure cooking before mixing with the lime pressure cooked organic material, (e) transferring the optionally mixed, organic materials from the mixing tank to at least one anaerobic biogas fermenter suitable for conducting an anaerobic, bacterial digestion of the organic material, where the anaerobic, bacterial digestion results in the generation of biogas, and (f) fermenting the organic material transferred to the anaerobic biogas fermenter under anaerobic fermentation conditions, and collecting the biogas resulting from the anaerobic fermentation of the organic material or (a) performing pre-incubation step comprising pre-incubation tank, organic material having a first portion removable inorganic nitrogen and organic nitrogen, and increasing amount of the removable inorganic nitrogen by converting the organic nitrogen into a second portion of removable inorganic nitrogen using first fermentation, where the pre-incubation step being free or substantially free from generation of biogas, (b) performing nitrogen stripping step by stripping the removable inorganic nitrogen, the first portion and the second portion, from the pre-incubated organic material using a lime-pressure cooker, (c) carrying out second fermentation step by anaerobically fermenting the pre-incubated material in an anaerobic biogas fermenter, the pre-incubated organic material that is mixed with a further organic material for the generation of biogas. An INDEPENDENT CLAIM is included for plant for generating biogas, which comprises (a) pre-incubation tank for hydrolyzing an organic material, pre-incubation tank being operably connected to a lime pressure cooker, (b) a lime pressure cooker for hydrolyzing a first organic material, (c) an absorption unit for absorbing and condensing ammonia fluids diverted to the absorption unit from the lime pressure cooker when first organic material is subjected to lime pressure cooking, (d) a mixing tank for mixing lime pressure cooked organic material with a further organic material before transferring the mixed, and organic materials to one or more fermenters, and (e) one or more fermenters for anaerobically fermenting organic materials, where fermentation results in the generation of biogas.