Abstract:
A water treatment method used in a water treatment device including a filter for filtering untreated water and a housing that houses the filter includes a step of putting the untreated water into the housing to obtain filtered water that has permeated through the filter, and a step of replacing the untreated water in the housing by storage water. The storage water is water having less favorable survival conditions for microbes than the untreated water.
Abstract:
A filtering device includes, as a filter membrane, a pleated filter formed of a filter base having folds so as to repeat peak portions and valley portions, the pleated filter having a shape of a cylinder whose axial direction is a ridge line direction of the folds. In the filtering device, the pleated filter is rotatable about a cylindrical axis of the shape of the cylinder. The filtering device includes a nozzle that is provided so as to face an outer circumferential surface of the pleated filter and that ejects a liquid toward the outer circumferential surface. The relationships 4p≦W, and h/5≦L≦h/2 are satisfied, where p represents a spacing between pleats and h represents a length in the ridge line direction, the length being effective for filtration, in the folds on the outer circumferential side of the pleated filter, and W represents an opening width in a direction perpendicular to the ridge line direction and L represents an opening length in the ridge line direction in an opening portion of the nozzle.
Abstract:
A ballast water treatment apparatus includes a cylindrical pleated filter that is rotatably held about an axis of a cylinder, a driving mechanism that rotates the pleated filter, an untreated water nozzle that ejects untreated water toward an outer circumferential surface of the pleated filter, a case that is provided so as to surround the pleated filter and that includes an outer cylindrical portion including a nozzle opening of the untreated water nozzle therein, a filtered water flow path that guides filtered water that has permeated through the pleated filter from the inside of the cylinder of the pleated filter to the outside of the case, and a discharge flow path that discharges discharged water that has not been filtered by the pleated filter to the outside of the case. The ballast water treatment apparatus further includes a reverse cleaning mechanism that supplies cleaning water to the inside of the cylinder of the pleated filter through the filtered water flow path.