Patent ID: 7029580

Claim:
A sludge concentrating apparatus comprising: a sludge tank which stores sludge; filtering means comprising a filter cloth that is shaped as an endless belt, and a plurality of rollers which turn the cloth, at least a lowermost one of the rollers being immersed in said sludge; a filtrate chamber including a filtrate introducing port through which filtrate from the filtering means flows into the filtrate chamber, the filter cloth being kept in close contact with the filtrate introducing port; cleaning means for removing sludge cakes adhering to the filter cloth; means for keeping a level of liquid in the filtrate chamber substantially constant; a sludge introducing means for introducing sludge to the sludge tank, said sludge introducing means being provided near an upper end of the filtrate introducing port; and concentrated sludge discharge means for discharging sludge from the sludge tank, said concentrated sludge discharge means being provided at a position substantially opposite to the sludge introducing means with the filter cloth therebetween; wherein the means for keeping the liquid level in the filtrate chamber substantially constant comprises one of: (a) a weir provided at a boundary between the filtrate chamber and an exit chamber into which the filtrate from the filtrate chamber flows, and (b) a riser tube which extends vertically in the filtrate chamber and communicates with a discharge pipe through which filtrate is discharged from the filtrate chamber.