SLUDGE TREATMENT SYSTEM

PROBLEM TO BE SOLVED: To provide a sludge treatment system capable, by returning, to a digestion tank, a sludge having an elevated condensed concentration, of improving the digestion efficiency within the digestion tank.SOLUTION: A sludge treatment system 10 includes: a solid-liquid separator 13 for solid-liquid separating and concentrating a digested sludge obtained by treating an organic effluent within a digestion tank 12; and a return line 14 for returning, to the inlet side of the digestion tank 12, the concentrated sludge from the solid-liquid separator 13, whereas the solid-liquid separator 13 includes: a concentrating unit 18 for gravity-filtering the digested sludge being conveyed atop the upper surface 17a of a filter cloth belt 17; and a mobilization mechanism 20 for mobilizing, along a direction intersecting the conveying direction of the filter cloth belt 17, the sludge being conveyed through the concentrating unit 18.