A device for filtering treating ballast water by way of a filtering method, and more particularly, to a compact and operability-enhancing multicage-type device for filtering ballast water, which distributes a lower portion of the device for filtering a discharge portion for discharging foreign substances after backwashing a filter and a backwash line, among features that are concentrated at an upper portion of the device for filtering, and communicates discharge tubes of each filtering unit in a single line, by considering the unique installation environment of the device for filtering that is coupled to a ship, thereby simplifying structure, reducing space required for installing the device for filtering in the upper portion of the device for filtering, allowing efficient maintenance by integrating foreign substance discharge and back pressure maintenance of each of the filtering units.

Provided are a separable two-stage vertical suction cleaning apparatus comprises: a first suction holder which has a first suction hole and is disposed such that the first suction hole faces the filter cloth of one of the two disks; a second suction holder which has a second suction hole for suctioning sludge and is disposed such that the second suction hole faces the filter cloth of the other of the two disks; a support provided above the first suction holder in order to support the first suction holder and the second suction holder; a first link mechanism connecting the support and the first suction holder; and a second link mechanism connecting the support and the second suction holder.

A suction device for a disc filter includes at least one suction bar per discoid filter body and a suction slit designed for suctioning the impurities of the filter cloth, as well as a suction pump for suctioning the impurities. The suction bar is movable radially from the axis of rotation of the disc filter.