FIELD: waste water purification. SUBSTANCE: purification of waste water containing organic and inorganic impurities includes two-step treatment of sediment suspensions produced in the biological purification of waste water. In the first step, suspension undergoes heat treatment at 150-220 C and 0.5-3.0 mPa pressure for 10-120 min. In the second step, when maintaining the same temperature, alkali is added to yield pH value more than 10, and then oxygen-containing gas is entered for 20-180 min under 1.5- 5.0 mPa pressure followed by reducing the pressure to normal value, cooling suspension to a temperature below 100 C, and separating suspension into solid and liquid phases. EFFECT: organic constituent of sediment is transformed into non-toxic compounds, and heavy metals of inorganic constituent into water-insoluble compounds. 2 cl, 1 dwg
