Wastewater sludge processing system

Abstract

The Wastewater sludge processing system takes sludge directly from the municipal waste water treatment plant and processes it using a low-temperature, low pressure process that has no waste products. The process dries the sludge and separates it into oil that is turned into biodiesel feedstock, cellulose/minerals that are used for heating the process, and water that is reused in the process.

1 . A zero-waste method of processing wastewater sludge such that at the end of the process, oil, cellulose, and minerals have been captured and there is substantially nothing left to be incinerated, landfilled, or otherwise disposed of, comprising the steps of;
 a—transferring solid wastewater sludge from a treatment plant to a wet sludge holding bin, said wastewater sludge containing from about 20 to 45% solids by weight,   b—drying said wastewater sludge to about 90% solids, grinding the dried wastewater sludge an transferring the dried ground sludge to a mixer reactor,   c—within the mixer reactor mixing the dried ground sludge with a solvent and heating to produce viscous suspension of hydrocarbons or cellulose and minerals in suspension,   d—separating liquids and solids,   e—heating the separated liquids to the boiling point of the solvent and the boiling point of the residual water prior and collecting evaporated solvent and residual water,   f—transferring solvent-free oil to a holding tank,   g—condensing evaporated solvent and residual water and separating water from solvent, and   h—transferring separated solvent and residual water to the mixer reactor of step (c).   
     
     
         2 . The method of  claim 1 , further comprising said step of separating liquids and solids is performed in a filter press,
 i—collecting cellulose-mineral mixture from said filter press   j—drying said cellulose-mineral mixture and removing and collecting solvent   k—reusing collected solvent in the process at step (c), and   l—transferring dried cellulose/mineral mixture to a furnace and using the heat from the furnace in at least one of steps (b), (c) and (e).   
     
     
         3 . The method of  claim 2 , wherein the oil from step (f) is approximately 80% fatty acids. 
     
     
         4 . The method of  claim 3 , wherein the oil from step (f) is approximately 65 weight % C16 and C18. 
     
     
         5 . The method of  claim 3 , wherein said oil is substantially free of sulfur. 
     
     
         6 . The method of  claim 1 , wherein the process extracts about 18% oil by weight from undigested sludge and 11% oil by weight from digested sludge. 
     
     
         7 . The method of  claim 1 , wherein said step of separating liquids and solids produces a filtrate comprising extracted oil, residual solvent, and traces of water. 
     
     
         8 . A zero-waste method of processing wastewater sludge such that at the end of the process, oil, cellulose, and minerals have been captured and there is substantially nothing left to be incinerated, landfilled, or otherwise disposed of, comprising the steps of;
 a—transferring solid wastewater sludge from a treatment plant to a wet sludge holding bin, said wastewater sludge containing from about 20 to 45% solids by weight,   b—drying said wastewater sludge to about 90% solids, grinding the dried wastewater sludge an transferring the dried ground sludge to a mixer reactor,   c—within the mixer reactor mixing the dried ground sludge with a solvent and heating to produce viscous suspension of hydrocarbons or cellulose and minerals in suspension,   d—separating liquids and solids,   e—heating the separated liquids to the boiling point of the solvent and the boiling point of the residual water prior and collecting evaporated solvent and residual water,   f—transferring solvent-free oil to a holding tank,   g—condensing evaporated solvent and residual water and separating water from solvent,   h—transferring separated solvent and residual water to the mixer reactor of step (c),   i—collecting cellulose-mineral mixture from step (d),   j—drying said cellulose-mineral mixture and removing and collecting solvent   k—reusing collected solvent in the process at step (c), and   l—transferring dried cellulose/mineral mixture to a furnace and using the heat from the furnace in at least one of steps (b), (c) and (e),   
       wherein the oil from step (f) is approximately 80% fatty acids and 65 weight % C16 and C18, and 
       wherein said step of separating liquids and solids produces a filtrate comprising extracted oil, residual solvent, and traces of water.