FILTRATION DEVICE, BALLAST WATER TREATMENT METHOD, AND BALLAST WATER TREATMENT DEVICE USING SAID FILTRATION DEVICE

摘要

A filtration device having a pleated filter as a filtration film, said pleated filter comprising a filter substrate that has folds which form repeating peak sections and trough sections and forming a cylindrical shape, the axial direction of which is the ridge line direction of the folds. The pleated filter is capable of rotating about the cylinder axis of the cylindrical shape, and is equipped with a nozzle that is provided so as to oppose the outer peripheral surface of the pleated filter, said nozzle spraying a liquid towards the outer peripheral surface. If the pleat interval is p and the ridge line direction length that is effective for filtration is h with respect to the outer peripheral folds of the pleated filter, and if the opening width that is orthogonal to the ridge line direction is W and the opening length in the ridge line direction is L with respect to the opening section of the nozzle, the filtration device satisfies the relationships 4p ≤ W and h/5 ≤ L ≤ h/2.