NOVELTY - The method for the treatment of alkaline nitrite-containing waste and sewage from solar cell production, comprises oxidizing nitrite by means of manganese(IV)- or manganese(VII)-containing oxidation agent in the presence of acid, to nitrate. The oxidation agent exists as solid material and is manganese dioxide. The nitrate-containing reaction product is provided as solution. The reaction product consists of 4 wt.% of nitrogen related to the total weight. The used acid comes from nitric acid-containing waste acid.    USE - Method for the treatment of alkaline nitrite-containing waste and wastewater from solar cell production useful in agriculture or horticulture as fertilizer (claimed).    ADVANTAGE - The method ensures easy, simple and safe treatment of alkaline nitrite-containing waste and sewage.    DETAILED DESCRIPTION - The method for the treatment of alkaline nitrite-containing waste and sewage from solar cell production, comprises oxidizing nitrite by means of manganese(IV)- or manganese(VII)-containing oxidation agent in the presence of acid, to nitrate. The oxidation agent exists as solid material and is manganese dioxide. The nitrate-containing reaction product is provided as solution. The reaction product consists of 4 wt.% of nitrogen related to the total weight. The used acid comes from nitric acid-containing waste acid. The manganese(IV)- or manganese(VII)-containing oxidation agent comes from waste or sewage. The manganese dioxide comes from battery production. The nitrite-containing waste and sewage comes from metal processing such as hardening or burnishing. The manganese(II) emerging during the oxidation of nitrite to nitrate is separated from the remaining reaction products, is reoxidized to manganese dioxide and is utilized as oxidation agent. The manganese(II) is precipitated from reaction solution as hydroxide. The reoxidation is carried out with atmospheric oxygen. The undesirable components such as heavy metals and fluoride are removed from the received solution. INDEPENDENT CLAIMS are included for:    (1) a method for the utilization of manganese(IV)- or manganese(VII)-containing waste or wastewater; and    (2) a nitrogen-containing concentrate.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of a method for the treatment of alkaline nitrite-containing waste and sewage (Drawing includes non-English language text).