NOVELTY - Generating biogas from anaerobic fermentation of processed organic material comprising solid and liquid portions, involves (a) diverting first organic material comprising one or more sources of nitrogen to pre-incubation tank and subjecting the organic material to mineralization by chemical and/or biological method, (b) diverting the pre-incubated first organic material to lime pressure cooker and subjecting the first pre-incubated organic material to lime pressure cooking, and (c) diverting pre-incubated and lime pressure cooked organic material to buffer tank.    USE - The method and plant are useful for generating biogas from anaerobic fermentation of processed organic material (all claimed).    ADVANTAGE - The method is cost-effective, and simple to perform, and consumes less energy, and generates 95% biogas from anaerobic fermented-processed organic material.    DETAILED DESCRIPTION - Method for generating biogas from anaerobic fermentation of processed organic material comprising solid and liquid portions, involves (a) diverting first organic material comprising one or more sources of nitrogen to pre-incubation tank and subjecting the organic material to mineralization by chemical and/or biological method, where the mineralization results in conversion of organic nitrogen present in organic material to inorganic nitrogen, (b) diverting the pre-incubated first organic material to lime pressure cooker and subjecting the first pre-incubated organic material to lime pressure cooking, where the lime pressure cooking step results in formation of ammonia fluids, and the ammonia fluids are diverted from the lime pressure cooker and hence separated from the organic material, and (c) diverting pre-incubated and lime pressure cooked organic material from the lime pressure cooker to buffer tank and lowering the pH value of the pre-incubated and lime pressure cooked material by contacting the pre-incubated and lime pressure cooked organic material in the buffer tank with a carbon dioxide containing gas. An INDEPENDENT CLAIM is included for plant for generating biogas from anaerobic fermentation of processed organic material comprising solid and liquid parts, which comprises (a) pre-incubation tank for mineralization of organic material by chemical or biological method, (b) lime pressure cooker for further mineralization of first organic material comprising one or more sources of nitrogen, (c) absorption unit for absorbing and condensing ammonia fluids diverted to the absorption unit from the lime pressure cooker, when the first organic material is subjected to lime pressure cooking, (d) buffer tank for mixing lime pressure cooked organic material with further organic material before diverting the mixed, organic materials to one or more fermenters, (e) gas storage unit suitable for storage of carbon dioxide containing gas, such as biogas, where the gas storage unit is operably connected to the buffer tank, and (f) one or more fermenters for anaerobically fermenting the organic materials diverted to one or more fermenters from the buffer tank, where the fermentation results in the generation of biogas.