The solution is a method and apparatus for energy treatment of dried sewage sludge. The dried sewage sludge is put into a pyrolysis reactor (1), where it is subjected to pyrolysis to form a sludge and a primary pyrolysis gas. The primary pyrolysis gas is discharged from the pyrolysis reactor (1) to the partial oxidation chamber (6), where it is subjected to partial oxidation to form a generator gas, which is then discharged through an inlet (26) to a wet scrubber (15) and from there to a fermenter or mixer of generator gas with biogas. The device comprises a pyrolysis reactor (1) with an inlet (2) for dried sewage sludge and an outlet (4) for sludge and an outlet (3) for primary pyrolysis gas. The outlet (3) for the primary pyrolysis gas is connected to the inlet of the partial oxidation chamber (6), which also has an inlet (8) for oxidizing air, an outlet (7) for solid fly ash and an outlet (9) for generator gas. The generator gas outlet (9) from the partial oxidation chamber (6) goes to the wet scrubber (15) and the generator gas outlet (16) from the wet scrubber (15) goes to the fermenter or mixer, to which the outlet of biogas of the fermenter is optionally led.