A rotating packed bed RPB that includes a first and second packed bed both arranged on the same rotatable shaft. A gas is directed via a gas inlet through the first packed bed in co-current flow with a liquid in a radially outward direction towards the outer radius of the packed bed. The liquid enters the first packed bed via a first liquid inlet. The gas exiting the first packed bed is directed to the second packed bed and forced through it in a radially inward direction in counter-current flow with a liquid, which enters through a second liquid inlet. The arrangement allows an operation of the rotating packed bed with less energy compared to RPBs of the prior art operating in counter-current flow only. The apparatus allows low-cost design and high design flexibility.