An apparatus for separating particles from an airflow, the apparatus comprising a housing comprising an inner wall, and a body positioned within the housing and separated therefrom so as to define a substantially annular flow path between the body and the inner wall. The housing is rotationally stationary, and the body is rotatable relative to the housing about a rotational axis, the body comprising an impeller section having a first set of blades extending from the body into the annular flow path towards the inner wall of the housing, the impeller being rotatable for generating airflow through the apparatus and for generating swirl within the airflow, and a turbine section located downstream of the impeller section, the turbine section having a second set of blades for recapturing rotational energy from the airflow.