SOLID-LIQUID SEPARATION METHOD

The disclosed solid-liquid separation method comprises: a suction filtration step, wherein, whilst decompressing a secondary-side space (5) which is the space on one surface side of a filter cloth (1), sludge (16) is supplied to a primary-side space (4) which is the space on the other surface side of the filter cloth (1), the sludge (16) is filtered by the filter cloth (1), and concentrated sludge (initial concentrated sludge) is attached to a primary-side surface (6) which is the other surface, as described above, of the filter cloth (1); a pressure filtration step, wherein the secondary-side space (5) is decompressed, both sludge is supplied to the primary-side space (4) and said space is pressurised, the sludge (16) is filtered by the filter cloth (1), and additional concentrated sludge (17) (second layer concentrated sludge) is attached on top of the concentrated sludge (16) (initial concentrated sludge) which is attached to the primary-side surface (6) of the filter cloth (1); a compression step wherein the concentrated sludge (17) attached to the primary-side surface (6) of the filter cloth (1) is compressed, and compressed sludge is obtained; and an extraction step wherein the compressed sludge is peeled off the filter cloth. The disclosed solid-liquid separation method uses a single solid-liquid separation device, and enables sludge which is 1% by mass solid content to be concentrated to sludge which is at least 40% by mass solid content.