A filtration apparatus that can include a filtering device can include disc sectors configured so that a vacuum can be applied to some disc sectors while compressed fluid is passed from a disc sector so that the fluid is passed into and/or through of at least one adjacent disc sector while that at least one disc sector is passed through a bath of the device configured to retain a slurry. Processes to retrofit a pre-existing filter device to include new disc sectors to form an embodiment of the filtration apparatus can include replacing old disc sectors with new disc sectors that are configured so that a vacuum can be applied to some disc sectors while compressed fluid is passed into and/or through at least one adjacent disc sector while that at least one adjacent disc sector is passed through a bath of the device configured to retain a slurry.