Use field: agriculture, production of poultry manure organic fertilizers. Objective: an invention is directed to providing wasteless, environmentally safe and cost- effective production of a target product of better quality at a minimal power consumption. Summary of the Invention: inventive method comprises performing fermentation of an initial product, removing a biogas, adding a flocculating agent, dehydrating a processed substrate, drying and granulating a fertilizer thus produced. Prior to fermentation, the poultry manure is mixed with water and said mixture is heated up to 25 - 35°C and agitated. A foam suppressant is added to the fermented substrate along with addition of a solution comprising iron sulphate and sulphuric acid. A dehydration water is subjected to dissolved air flotation. A flotation sludge is returned for chemical retreatment. An effluent water resulting from flotation is purified and mixed with poultry manure. A post-treatment concentrate resulting from reverse osmosis purification is
