TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: The lysis is induced within the apparatus. The separating step is carried out in a centrifugal separator. The aqueous medium is concentrated before lysing the cellular material. The cellular material is fed to the rotational separator using a pressure of 5-200 bar. Preferred Components: The aqueous medium is a substantially unprocessed harvested growth medium containing the cellular material. The cellular material is algae and the first fraction comprises algal lipids.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The centrifugal separator comprises a rotatably arranged upwardly extending first element with elongate elements connected to it and an upwardly extending second element, where the first and second elements are concentrically arranged with respect to each other resulting in an inner element (3) and an outer element (4), and the elongate elements extend from the first element towards the second element. The centrifugal separator further comprises: a supply opening arranged at an outer end of the separator on a radius between the inner element and outer element for supplying a dispersion comprising particles to be separated; and a discharge opening arranged at an opposite outer end for discharging separated fluid and/or particles, where the supplying opening is arranged proximate to the outer element. The lysis device: is arranged to induce a collision of the aqueous medium supply stream with at least one rough surface of the lysis device; comprises a rotatable and static holder supporting the rough surface, where the static holder is arranged opposite the rotatable holder to create a flow path for the aqueous medium supply stream so that the collision with the rough surface is induced for lysing the cellular material. The rotatable holder and/or the static holder support an upstanding rib comprising the rough surface, where the rough surface comprises sintered material. The apparatus comprises a supply opening arranged at an outer end of the separator for supplying the aqueous medium comprising the cellular material to be separated and further comprises a discharge opening arranged at an opposite outer end for discharging separated fractions. EXAMPLE - No suitable example given.