Two-stage mechanical dewatering of sewage sludge
Patent 4244287 Issued on January 13, 1981. Estimated Expiration Date: 
July 9, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
July 9, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesBaled wood chips Mechanical dewatering process Patent #: 4160732 InventorAssigneeApplicationNo. 06/055569 filed on 07/09/1979US Classes:100/37, With separation from material of liquid expressed100/41, Forcing through constricted passage34/380With nondrying treating of materialExaminersPrimary: Camby, John J.Attorney, Agent or FirmInternational ClassesB30B 9/12 (20060101)B30B 9/02 (20060101) B30B 9/26 (20060101) C02F 11/12 (20060101) B01D 36/02 (20060101) B01D 36/00 (20060101) B01D 29/13 (20060101) B01D 29/25 (20060101) AbstractSewage sludge is dewatered in a two-stage process. The first stage dewaters the sludge to a solids content above about 40 to 45 wt. %. The first zone comprises a cylindrical porous chamber with a centrally mounted screw conveyor which does not contact the porous wall of the chamber. The second stage further dewaters the sludge. The second stage applies pressure directly, as with a piston, to a stationary quantity of sludge which is in contact with a porous wall. The effectiveness of the second stage is increased through use of the first stage, which reduces the thixotropic nature of the sludge by dewatering it. | |
