A filter apparatus is provided for the filtering of substances from a fluid having a filter housing (2) which bounds a filter space (6) and which has an inlet (3) and an outlet (4) for the fluid to be filtered and having a filter element (5) which is provided in the filter space (6) and which is designed and arranged so that the filtering fluid can only flow through the filter element (5) from the inlet (3) to the outlet (4) of the filter housing (2) in operation, wherein a heating device (10) is provided for the heating of the fluid which includes a microwave source (11) in order to act on the fluid by microwaves.