A wet scrubber (8) for cleaning a process gas containing sulphur dioxide comprises an absorption vessel (40) operative for bringing the process gas into contact with an absorption liquid to absorb sulphur dioxide from the process gas. The wet scrubber (8) further comprises an acidification system (90) operative for mixing absorption liquid that has absorbed sulphur dioxide from the process gas with a carbon dioxide containing gas, an absorbent dissolution tank (54) operative for adding an absorbent material to at least a portion of the absorption liquid, and a return pipe (104) operative for returning to the absorption vessel (40) at least a portion of the absorption liquid that has been mixed with the carbon dioxide containing gas.