Dewatering esp. of clarification sludge - by combined centrifugal filtering and pressurised gas filtering

摘要

Dewatering of sludge (esp. clarification sludge) is in a solid casing screw centrifuge with a sieve portion. After pre-dewatering in the clarification portion of the centrifuge, the sludge is post-dewatered in the sieve portion. Pressurised gaseous medium is applied from the interior onto the sludge layer in the sieve portion region. A solid casing screw centrifuge for carrying out the process has at least two spaced dam elements (38,39) mounted externally on the hollow screw shaft (37) and dipping, respectively before and beyond the sieve portion (36), in the thick sludge layer, a compressed gas supply line (42) being provided within the shaft (37) for directing gas onto the sludge layer in the sieve portion region. ADVANTAGE - Continuously operating centrifuge combines centrifugal filtration with pressurised gas filtration without the entire centrifuge housing being held under pressure.