Apparatus and process for producing an organic product from sewage sludge

Abstract

A completely integrated and automated apparatus by which liquid sewage sludge from any sewage or waste treatment plant may be processed into a completely dry, pelletized and sterilized product of an organic nature containing nutrients valuable for the support of plant life. The apparatus involves one completely integrated and automated unit together with a control center by means of which electric circuits program each component of the apparatus to automatically regulate the operation of each component, so that no labor or other manpower is required in the operation, except for observation, lubrication, maintenance and repair of the various motors and machineries involved.

I claim: 
     
       1. A process for producing an organic product from sewage sludge comprising mixing a predetermined quantity of liquid waste sewage sludge with a chemical for coagulating or flocculating the solids contained in the liquid sludge, subjecting the mixture to pressure for extracting a part of the moisture therefrom, draining off the extracted moisture, heat drying and pelletizing the dewatered material to produce pellets .Iadd.during the drying.Iaddend., subjecting the dry pelletized material to a suction action .[.for separating.]. .Iadd.to convey said pellets through the drying and to separate .Iaddend.dust and fine particles of sludge material from the pellets, discharging the separated pellets by gravity to storage, and mixing the dewatered material with a portion of the previously produced pellets for drying and preheating the material prior to the heat drying and pelletizing thereof, so as to enable drying temperatures to be low enough to prevent formation of clinkers and the ignition of the organic material. 
     
     
       2. A process as defined by claim 1, including the step of cleaning and separating the dust and fine particles from air in which the pellets are conveyed. 
     
     
       3. A process as defined by claim 1, including the step of cleaning and separating the dust and fine particles from air in which the pellets are conveyed by wet scrubbing. 
     
     
       4. A process as defined by claim 3, including recycling the separate solids. 
     
     
       5. A process as defined by claim 4, including the step of discharging the moisture laden cleansed air to the atmosphere. .Iadd.6. A process for producing an organic product from sewage sludge comprising mixing a predetermined quantity of liquid waste sewage sludge with a chemical for coagulating or flocculating the solids contained in the liquid sludge, subjecting the mixture to pressure for extracting a part of the moisture therefrom, draining off the extracted moisture, heat drying and pelletizing the dewatered material to produce pellets in a dryer, applying suction to the dryer to cause drying air to flow therethrough along with the solids and to convey said pellets from the dryer for separating dust and fine particles of sludge material from the pellets, discharging the separated pellets by gravity to storage, and mixing the dewatered material with a portion of the previously produced pellets for drying and preheating the material prior to the heat drying and pelletizing thereof, so as to enable drying temperatures to be low enough to prevent formation 
     
     
        of clinkers and the ignition of the organic material. .Iaddend. .Iadd.7. A process for producing an organic product from sewage sludge comprising mixing a predetermined quantity of liquid waste sewage sludge with a chemical for coagulating or flocculating the solids contained in the liquid sludge, subjecting the mixture to pressure for extracting a part of the moisture therefrom, draining off the extracted moisture, heat drying and pelletizing the dewatered material to produce pellets by feeding the dewatered material and drying air to a dryer, heat drying and pelletizing the dewatered material in said dryer by flowing said air and dewatered material concurrently therethrough, and conveying pellets formed within said dryer from said dryer by suction flow of said drying air from said dryer for separating dust and fine particles of sludge material from the pellets, discharging the separated pellets by gravity to storage, and mixing the dewatered material with a portion of the previously produced pellets for drying and preheating the material prior to the heat drying and pelletizing thereof, so as to enable drying temperatures to be low enough to prevent formation of clinkers and the ignition of the organic 
     
     
        material. .Iaddend. .Iadd.8.  A process as defined by claim 7 wherein said separation occurs in an air-solids Separator which receives said air and pellet output of said dryer and separates the air, dust and fine particles from the pellets. .Iaddend. .Iadd.9. A process as defined by claim 8 wherein the output of said dryer fed to said separator constitutes air, dust and fine particles and pellets which constitute the product. .Iaddend.