Abstract: A process and an apparatus for mechanically dewatering municipal sewage sludge or peat. The undewatered feed material is passed into the first end of a cylindrical porous wall and pressurized within the cylindrical wall by a rotating screw conveyor, which also transports the solids toward the second end of the cylindrical wall. The screw conveyor comprises a central shaft which has at least two built-up sections of gradually increasing diameter providing a compression ratio of 2.5:1.0. The flight depth of the screw conveyor increases by a factor greater than 2.0 after each built-up section. The distance between the edge of the screw conveyor blade and the inner surface of the cylindrical wall and the structure of the openings in the wall have specific dimensional limitations. Fibrous additives may be used to aid in dewatering peat and secondary sludges.

Abstract: A process for drying and granulating sewage sludge. Wet sewage sludge is at least partially dried in a thermal drying zone, which preferably is a toroidal dryer. A plasticizer is added to the dried sludge and the resultant mixture is extruded to form fertilizer granules. An extrusion aid may also be admixed with the dried sludge.

Abstract: Sewage 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.

Abstract: A process for mechanically dewatering fibrous organic wastes such as sewage sludge. The undewatered waste is passed into the first end of a cylindrical dewatering zone having a porous outer wall. A helical blade rotated within the dewatering zone pressurizes the waste and moves it to the outlet at the second end of the dewatering zone. A filter media comprising a cylindrical substantially unagitated layer of fibrous material derived from the waste is retained within an annular space located between the outer edge of the helical blade and the inner surface of the porous wall. Two or more dewatering zones and mixing zones are used in series to achieve the desired degree of dryness.

Abstract: A process for mechanically dewatering fibrous organic waste such as sewage sludge. The undewatered waste is passed into the first end of a cylindrical dewatering zone having a porous outer wall. A helical blade rotated within the dewatering zone pressurizes the waste and moves it to the outlet at the second end of the dewatering zone. A filter media comprising a cylindrical substantially unagitated layer of fibrous material derived from the waste is retained within an annular space located between the outer edge of the helical blade and the inner surface of the porous wall. The longitudinal support rods of the porous wall are located on the inner surface of the porous wall and protrude into the fibrous material.

Abstract: A process for drying and granulating sewage sludge. Wet sewage sludge is dried in either a thermal drying zone or a mechanical dewatering zone comprising a cylindrical chamber having a porous wall and a centrally mounted rotating helical screw conveyor which does not contact the porous wall. A plasticizer is added to the dried sludge and the resultant mixture is extruded to form fertilizer granules. Also disclosed is a process for filtering suspended solids from a water stream using the apparatus of the mechanical dewatering zone.

Abstract: A composition of matter comprising a plasticized organic waste, preferably dried sewage sludge. Fibrous reinforcing media may also be present. Plasticization of the dried organic waste is performed by the simultaneous application of an elevated temperature and pressure. Articles of manufacture are produced by extruding or otherwise forming the plasticized organic waste into a desired shape and then cooling the formed material.

Abstract: A process for mechanically dewatering fibrous organic waste such as sewage sludge. The underwatered waste is passed into the first end of a cylindrical dewatering zone having a porous outer wall. A helical blade rotated within the dewatering zone pressurizes the waste and moves it to the outlet at the second end of the dewatering zone. A filter media comprising a cylindrical substantially unagitated layer of fibrous material derived from the waste is retained within an annular space located between the outer edge of the helical blade and the inner surface of the porous wall.

Abstract: A process for drying organic waste, such as sewage sludge, by contacting the organic waste with hot vapors wherein the dried material is extruded to form compacted granules having good flow characteristics and suitable for application by commercial fertilizer spreaders.

Abstract: A process for drying organic waste, such as sewage sludge, by contacting the organic waste with hot vapors. In the preferred embodiment, adsorption of hydrocarbons vaporized during the drying step is achieved by mixing recycled dried solids into the drying zone effluent stream. The drying zone effluent stream is then separated into vapor and solids streams, with a portion of the solid stream being recycled as the adsorbent. The unrecycled portion of dry solids is preferably extruded in a separate operation to form compacted granules having good flow characteristics and suitable for application by commercial fertilizer spreaders. In another embodiment, a vapor stream derived from the drying zone effluent stream is contacted with the dry solids downstream of the solids-vapor separation zone to effect the adsorption of hydrocarbon vapors.

Abstract: A process for drying organic waste, such as sewage sludge, by contacting the organic waste with hot vapors wherein the dried material is plasticized and extruded to form compacted granules having good flow characteristics and suitable for application by commercial fertilizer spreaders. A plasticizer and an extrusion aid are added to the dried material prior to extrusion.

Abstract: A process for drying organic waste, such as sewage sludge, by contacting the organic waste with hot vapors. Partial dewatering of the organic waste is achieved by admixture with a recycled portion of dried solids followed by extrusion of the mixture. The resultant extrudate is then dried, and the unrecycled portion is extruded in a separate operation to form compacted granules having good flow characteristics and suitable for application by commercial fertilizer spreaders. A plasticizer and an extrusion aid may be added to the dried material prior to extrusion.