Abstract: Apparatus for thickening sludge comprising a driven foraminous belt (10) having a conveying surface arranged at least substantially horizontally, a chute (14) for feeding a matt of sludge onto the belt (10) at one end of the conveying run, and a plurality of parallel flexible strips (21) of material attached at one end to the output end of the chute (14) and allowed to rest freely upon the belt (10) at the other end, whereby the sludge passes onto the belt in one or more strips whose width is substantially less than that of the belt, thus to leave one or more zones of the belt free of sludge to permit drainage of water therefrom through the belt, there being a plurality of deflecting members (22) disposed downstream of the output ends of the strips (21) and adapted to deflect a portion of each strip of sludge onto the next adjacent part of the belt left free of sludge thus to produce a matt thereof of substantially uniform thickness extending across the belt.