Biosolids digester and process for biosolids production

Abstract

The invention relates to methods and apparatuses for producing Class A biosolids. In yet another embodiment, the invention relates to a method comprising digesting waste material by anaerobic digestion, and yielding Class A biosolids. In still yet another embodiment, the invention relates to a system for anaerobic digestion of waste material to produce Class A biosolids. In still yet another embodiment, the invention relates to a system for anaerobic digestion of waste material comprising a mixing chamber, a digester, a heating pit, and an effluent pit.

What is claimed is: 
     
         1 . A waste processing system comprising: a closed container comprising an anaerobic digester with a first passage and a second passage separated by a center wall, wherein the digester has outside walls, and further wherein the center wall and outside walls are substantially planar and vertical; and a heating pit that is adjacent to the anaerobic digester and shares a wall with the anaerobic digester, wherein the heating pit comprises a first heating device with heating pipes. 
     
     
         2 . A waste processing system comprising: a closed container comprising an anaerobic digester with a first passage and a second passage separated by a center wall, wherein the digester has outside walls, and further wherein the center wall and outside walls are substantially planar and vertical; a heating pit that is adjacent to the anaerobic digester and shares a common wall with the anaerobic digester, wherein the heating pit comprises a first heating device to move waste material in a cork-screw-like fashion; and an effluent pit that is adjacent to and shares a common wall with the heating pit, and wherein the effluent pit comprises heating racks to capture excess heat. 
     
     
         3 . The system of  claim 2 , wherein the heating pit is configured to store one day of waste material. 
     
     
         4 . The system of  claim 2 , wherein the effluent pit is configured to store one day of waste material. 
     
     
         5 . The system of  claim 2 , wherein the first heating device includes a conduit having at least one gas outlet positioned to promote upward movement of the heated waste material utilizing recycled biogas. 
     
     
         6 . The system of  claim 2 , wherein the first heating device contains a heating medium. 
     
     
         7 . The system of  claim 2 , further comprising a second heating device positioned in at least a portion of one of the first passage and the second passage to heat the waste material that comes in contact with the heating device to cause thermal mixing of the waste. 
     
     
         8 . The system of  claim 7 , wherein the second heating device is positioned adjacent a wall. 
     
     
         9 . The system of  claim 7 , wherein the second heating device is positioned adjacent the divider of the digester. 
     
     
         10 . The system of  claim 7 , wherein the second heating device includes a pipe containing a heating medium. 
     
     
         11 . The system of  claim 10 , wherein the heating medium comprises water. 
     
     
         12 . The system of  claim 10 , wherein the heating medium comprises a gas 
     
     
         13 . The system of  claim 2 , wherein waste material in the heating pit is heated to a temperature from 140° to 180° F. 
     
     
         14 . The system of  claim 2 , wherein the heating pit comprises a weir wall. 
     
     
         15 . The system of  claim 2 , further comprising a sludge pit located between the heating pit and the effluent pit. 
     
     
         16 . A waste processing system comprising: a closed container comprising an anaerobic digester including a mixing chamber, wherein said mixing chamber comprises heating coils that can heat at least to 100° F.; and a methanogenic chamber for digesting the waste material; a heating pit that is adjacent to and shares a common wall with the methanogenic chamber, wherein the heating pit comprises a weir wall for plug flowing the waste material from the methanogenic chamber, and further wherein the waste material is heated to a temperature from 140° F. to 180° F. in the heating pit; and an effluent pit that is adjacent to the heating pit, wherein the effluent pit comprises heating racks for capturing excess heat from the waste material. 
     
     
         17 . The system of  claim 16  further comprising a hot water tank to supply heat to the methanogenic chamber. 
     
     
         18 . The system of  claim 16  further comprising an engine, wherein exhaust air from the engine can be supplied to the heating pit for mixing of the waste material. 
     
     
         19 . The system of  claim 16 , wherein the heating pit comprises a first heating device comprising a conduit having at least one gas outlet positioned to promote upward movement of the heated waste material utilizing recycled biogas.