PURPOSE: To enable uninterrupted dewatering/filtration treatment alternately effecting a filtration process, in which compressed air is applied to a dewatering/filtration device partitioned into a cake filtration chamber and a drainage chamber, a filtration member being interposed therebetween, and a regeneration process, in which compressed air is applied to the drainage chamber.

CONSTITUTION: Compressed air is introduced into a dewatering/filtration chamber 3, into which muddy water has been poured, through a compressed air introducing path 15, whereupon the dewatering/filtration chamber 3 is pressurized with said compressed air, and simultaneously, the muddy water in the dewatering/filtration chamber 3 is filtered with a filtration member 5 by pressing down said muddy water. When filtering capacity of the filtration member 5 is lowered by a clogging of said filtration member 5 owing to jamming thereof during the filtration of the muddy water, introduction of the compressed air in the dewatering/ filtration chamber 3 is stopped, and compressed air is introduced into a drainage chamber 7 through a compressed air introduction path 41, and the filtration member 5 is jetted into the dewatering/filtration chamber after passing it through the filtration member 5 from the drainage chamber 7, so that the clogging of the filtration member 5 is dissolved, whereby the filtration member is regenerated. Subsequently, the introduction of the compressed air into the drainage chamber 7 is stopped and the compressed air is again introduced into the dewatering/filtration chamber 3, whereby filtration of the muddy water and regeneration of the filtration member are alternately effected.