Solid fuel from brown grease and methods and systems for brown grease and sewage sludge recycling

Abstract

A method and system for making solid fuel from brown grease includes providing brown grease, dewatering the brown grease, and combining the dewatered brown grease with a combustible material under conditions effective to make a solid fuel. A method and system for making a fertilizer material from sewage sludge includes providing sewage sludge, providing steam generated by combusting a fuel comprising brown grease, and contacting the sewage sludge with the steam under conditions effective to dewater the sewage sludge and render a fertilizer material.

1 . A method of making solid fuel from brown grease, said method comprising:
 providing brown grease;   dewatering the brown grease; and   combining the dewatered brown grease with a combustible material under conditions effective to make a solid fuel.   
   
   
       2 . The method according to  claim 1  further comprising adding a base to the brown grease prior to said dewatering under conditions effective to raise the pH of the brown grease. 
   
   
       3 . The method according to  claim 2 , wherein the pH of the brown grease is raised to a pH above about 8.5. 
   
   
       4 . The method according to  claim 2 , wherein the base is lime. 
   
   
       5 . The method according to  claim 1  further comprising treating the brown grease with a polymer solution. 
   
   
       6 . The method according to  claim 5 , wherein the polymer solution comprises a cationic emulsion. 
   
   
       7 . The method according to  claim 1 , wherein the dewatered brown grease contains about 50% solids. 
   
   
       8 . The method according to  claim 1 , wherein the combustible material is sawdust. 
   
   
       9 . A solid fuel comprising:
 brown grease and   at least one combustible material combined with the brown grease.   
   
   
       10 . The solid fuel according to  claim 9 , wherein the brown grease is dewatered brown grease. 
   
   
       11 . The solid fuel according to  claim 10 , wherein the dewatered brown grease contains about 50% solids. 
   
   
       12 . The solid fuel according to  claim 9 , wherein the brown grease has a pH above about 8.5. 
   
   
       13 . The solid fuel according to  claim 9 , wherein the brown grease and the combustible material are present in the solid fuel in a ratio of about two parts combustible material to about one part brown grease by volume or by weight. 
   
   
       14 . The solid fuel according to  claim 9 , wherein the combustible material is sawdust. 
   
   
       15 . A method of generating energy from brown grease, said method comprising:
 dewatering brown grease and   combusting the dewatered brown grease under conditions effective to generate energy.   
   
   
       16 . The method according to  claim 15  further comprising adding a base to the brown grease prior to said dewatering under conditions effective to raise the pH of the brown grease. 
   
   
       17 . The method according to  claim 16 , wherein the pH of the brown grease is raised to a pH above about 8.5. 
   
   
       18 . The method according to  claim 15  further comprising treating the brown grease with a polymer solution prior to said dewatering. 
   
   
       19 . The method according to  claim 18 , wherein the polymer solution comprises a cationic emulsion. 
   
   
       20 . The method according to  claim 15 , wherein the dewatered brown grease contains about 50% solids. 
   
   
       21 . The method according to  claim 15  further comprising combining the dewatered brown grease with a combustible material prior to said combusting. 
   
   
       22 . The method according to  claim 21 , wherein the brown grease and the combustible material are combined in a ratio of about two parts combustible material to about one part dewatered brown grease by volume or by weight. 
   
   
       23 . The method according to  claim 21 , wherein the combustible material is sawdust. 
   
   
       24 . The method according to  claim 21 , wherein the combined dewatered brown grease is baked under conditions effective to render a combined dewatered brown grease having about 90% solids. 
   
   
       25 . A system for making solid fuel from brown grease, said system comprising:
 a dewatering unit capable of dewatering brown grease and   a mixing unit capable of combining dewatered brown grease with a combustible material to make a solid fuel from dewatered brown grease.   
   
   
       26 . The system according to  claim 25 , wherein the dewatering unit comprises at least one of a mechanical separator, a chemical separator, and a thermal separator. 
   
   
       27 . The system according to  claim 25  further comprising sensors operably connected to the dewatering unit and the mixing unit. 
   
   
       28 . The system according to  claim 27  further comprising a control system coupled to control the operation of the sensors, the dewatering unit, and the mixing unit, whereby the system is automated. 
   
   
       29 . A method of making solid fuel from brown grease, said method comprising:
 providing brown grease and   dewatering the brown grease under conditions effective to make a solid fuel.   
   
   
       30 . The method according to  claim 29  further comprising adding a base to the brown grease prior to said dewatering under conditions effective to raise the pH of the brown grease. 
   
   
       31 . The method according to  claim 30 , wherein the pH of the brown grease is raised to a pH above about 8.5. 
   
   
       32 . The method according to  claim 29 , wherein the dewatered brown grease contains about 50% solids. 
   
   
       33 . A solid fuel comprising dewatered brown grease. 
   
   
       34 . The solid fuel according to  claim 33 , wherein the brown grease has a pH above about 8.5. 
   
   
       35 . A method of making a fertilizer material from sewage sludge, said method comprising:
 providing sewage sludge;   providing steam generated by combusting a fuel comprising brown grease; and   contacting the sewage sludge with the steam under conditions effective to dewater the sewage sludge and render a fertilizer material.   
   
   
       36 . The method according to  claim 35 , wherein the fuel comprises:
 dewatered brown grease and   a combustible material.   
   
   
       37 . The method according to  claim 35 , wherein said contacting is carried out in a steam paddle dryer. 
   
   
       38 . The method according to  claim 35 , wherein the sewage sludge is dewatered to contain a minimum of about 90% solids. 
   
   
       39 . The method according to  claim 35 , wherein the fertilizer material is a class A Biosolid fertilizer. 
   
   
       40 . The method according to  claim 35  further comprising combining ash generated from the combusted fuel with the fertilizer material. 
   
   
       41 . A system for making fertilizer material from sewage sludge, said system comprising:
 a system for making solid fuel from brown grease, said system comprising a dewatering unit capable of dewatering brown grease under conditions effective to make a solid fuel;   a solid fuel boiler capable of combusting solid fuel from the system for making solid fuel to generate steam; and   a steam dryer for dewatering sewage sludge, wherein the steam dryer is coupled to the solid fuel boiler, whereby steam from the solid fuel boiler contacts the steam dryer thereby dewatering sewage sludge contained in the steam dryer to render a fertilizer material.   
   
   
       42 . The system according to  claim 41 , wherein the dewatering unit comprises at least one of a mechanical separator, a chemical separator, and a thermal separator. 
   
   
       43 . The system according to  claim 41 , wherein the system for making solid fuel from brown grease further comprises a mixing unit capable of combining dewatered brown grease with a combustible material. 
   
   
       44 . The system according to  claim 41 , wherein the steam dryer is a paddle steam dryer.