A continuous microfiltration machine for removing suspended solid particles from process and waste water comprises a container (2) with an inlet conduit (4) defining a flow direction (F), and having therein an influent chamber (7) for feeding the liquid to be filtered, a treatment chamber (8) with a bottom wall (9), at least one pair of filter disks (10) keyed to a shaft (12) perpendicular to the flow direction (F) and having inner filter surfaces (10′) outer surfaces (10″) and outer peripheral edges (15) in sliding contact with the bottom wall (9), an effluent chamber (17) for receiving the filtered liquid, with a discharge conduit (18), drive means (13, 14) for imparting rotation to the disks, first jet washing means (20) directed against the outer surfaces (10″) of the disks (10) for removing the particles retained thereby, a first collecting duct (24) for collecting the removed particles, which is interposed between the disks (10) and has substantially parallel side edges (25) located at a predetermined minimum distance (D) from the inner surfaces (10′) of the disks (10). The inner surfaces (10′) of the disks are substantially flat and continuous surfaces, with a flatness error (ε) smaller than said predetermined minimum distance (D).