NOVELTY - The method for the recovery of chemicals from sewage that arises during the production of fibrous material from lignocellulose raw material under use of sulfur salt, comprises subjecting the sewage to an anaerobic sewage treatment for producing sulfur and/or sulfur compounds and for producing methane and/or carbon dioxide. The sulfur salt (70%) contained in the sewage is converted into sulfur and/or sulfur compound through the anaerobic sewage treatment. Psychrophilic, mesophilic or thermophilic microorganisms are used for the anaerobic sewage treatment.    USE - Method for the recovery of chemicals from sewage that arises during the production of fibrous material from lignocellulose raw material under use of sulfur salt.    ADVANTAGE - The method ensures simple, efficient and economic recovery of chemicals from sewage with high yield and low operating and investment cost by requiring less quantity of chemicals.    DETAILED DESCRIPTION - The method for the recovery of chemicals from sewage that arises during the production of fibrous material from lignocellulose raw material under use of sulfur salt, comprises subjecting the sewage to an anaerobic sewage treatment for producing sulfur and/or sulfur compounds and for producing methane and/or carbon dioxide. The sulfur salt (70%) contained in the sewage is converted into sulfur and/or sulfur compound through the anaerobic sewage treatment. Psychrophilic, mesophilic or thermophilic microorganisms are used for the anaerobic sewage treatment. After the anaerobic sewage treatment, methane is stored in a storage, and an alkaline filtrate is available from which high-molecular lignin is separated. Chemical oxygen demand (40%) available in the sewage is removed through the anaerobic sewage treatment. The chemical oxygen demand content of the sewage is 40-100 g/l. Hydrogen sulfide produced through the anaerobic sewage treatment is converted subsequently with water and with alkaline filtrate to alkali sulfide. After the anaerobic sewage treatment, gaseous or dissolved sulfur dioxide with alkaline filtrate is converted to alkali sulfite and the elementary sulfur is burned to sulfur dioxide and converted with alkaline filtrate to alkali sulfite. Aerobic or anaerobic pretreatment is carried out before the anaerobic sewage treatment.