SUCTION FILTRATION/CONCENTRATION METHOD

PROBLEM TO BE SOLVED: To achieve condensation of sludge which is low concentration of ≤1 mass% generated in a water purification plant or the like in a short time and in an efficient manner using the suction filtration/concentration method.SOLUTION: There is provided a suction filtration/concentration method for filtrating and concentrating suspension by a suction method, which comprises a step in which water content in the suspension is passed through filter cloth in the shape of a bag by sucking the suspension through a filtering chamber formed in the interior of the filter cloth, while solids in the suspension are attached to the surface of the filter cloth. The suction filtration/concentration method has a step for selecting first suspension containing solid content which can block the mesh of the filter cloth, a cake thin layer forming step for forming a cake thin layer on the surface of the filter cloth by filtrating and concentrating the first suspension by the suction method, and a filtration/concentration step for filtrating and concentrating second suspension having concentration lower than the concentration of the first suspension through the cake thin layer by the suction method.