Sludge screw thickener with screen rotation during cleaning

Abstract

A screw press has a cylindrical screening section mounted to a frame. The screening section is able to rotate but can be prevented from rotating. A sprayer system is operable to spray water on the screening section. In a cleaning process, the screening section is rotated while water is sprayed against it. Optionally, the power required to rotate the screen may be provided by an auger drive mechanism. The screening section may have openings sized to retain flocculated solids. The screw press may be used to thicken a sludge from a waste water treatment plant.

1 . A screw press having a screening section that may be selectively fixed or allowed to rotate. 
     
     
         2 . The screw press of  claim 1  wherein the screening section is generally cylindrical and mounted to a frame of the screw press such that the screening section may rotate relative to the frame. 
     
     
         3 . The screw press of  claim 1  comprising a releasable restraint between the screening section and the frame. 
     
     
         4 . The screw press of  claim 1  further comprising a sprayer system located outside of the screening body. 
     
     
         5 . The screw press of  claim 1  further comprising an auger within the screening body. 
     
     
         6 . The screw press of  claim 1  wherein the auger has a shaft with increased diameter towards an outlet end of the screw press. 
     
     
         7 . The screw press of  claim 1  comprising a motor adapted to rotate the screening section. 
     
     
         8 . The screw press of  claim 7  wherein the motor is adapted to rotate the screening section by way of rotating the auger while the screening section is allowed to rotate. 
     
     
         9 . The screw press of  claim 7  comprising a detachable connection between the motor and the screening section. 
     
     
         10 . The screw press of  claim 1  wherein the screening section has openings sized to remove floc from a sludge. 
     
     
         11 . The screw press of  claims 1  wherein the screening section comprises wedgewire with a slot opening in the range from about 0.25 mm to about 0.75 mm. 
     
     
         12 . A screw press having a screening section with openings sized to remove floc from a sludge. 
     
     
         13 . The screw press of  claim 12  wherein the screening section comprises wedgewire with a slot opening in the range from about 0.25 mm to about 0.75 mm. 
     
     
         14 . The screw press of  claim 12  having an auger with a constant outside diameter. 
     
     
         15 . The screw press of  claim 14  wherein the auger has a shaft with increased diameter towards an outlet end of the screw press. 
     
     
         16 . A screw press comprising a screening section and an auger, wherein the auger has a shaft with an increased diameter towards an outlet end of the screw press. 
     
     
         17 . A process of operating a screw press comprising a step of spraying water against a screening section of the screw press. 
     
     
         18 . The process of  claim 17  further comprising a step of rotating the screening section while spraying water against it. 
     
     
         19 . The process of  claim 17  wherein the screening section is rotated by power supplied by a motor that rotates an auger of the screw press. 
     
     
         20 . The process of  claim 17  comprises a step of releasing a restraint on the screening section such that rotation of the auger causes rotation of the screening section. 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . (canceled)