PURPOSE: In a sewage disposal ship installed with a precipitation chamber, filtration chamber, and disposal chamber, to dispose sewage efficiently by sucking the filter material deteriorated in filtration performance by means of a jet in the upper portion of the filtration chamber and providing a filter material washer for separating the filth adhered to the filter material.

CONSTITUTION: A sewage disposal ship is provided with a sewage inlet port 9, precipitation chamber 8, supernatant passage 12, filtration chamber 1, filtrate feed pipe 14, and disposal chamber 13 and conducts sewage disposal. When the filtration performance of the filter material has been deteriorated, the filter material is sucked up via a suction port 2 through the function of a jet 17 arranged in the course of a filter material riser pipe 4, and fed through a discharge port 3 into a separation chamber 6, where the filter material is separated from the filth adhered thereto. The filter material recovered in filtration performance is returned into the filtration chamber 1 and used for sewage disposal; the separated filth is precipitated in the precipitation chamger 8.