Abstract:
A multi stage process for the separation of bio-components from a waste stream containing Dried Distillers Grains with Solubles is disclosed. Targeted polymers are added to the source and separated streams prior to passing the streams through separation equipment including a rotary screen, a press, and a dissolved air floatation in which the waste stream is separated into a stream containing predominantly protein, a stream containing predominantly oil, a stream containing predominantly water and a stream that contains predominantly fibers.

Description:
RELATED APPLICATIONS 
     This application is a continuation in part application claiming priority from non-provisional application Ser. No. 14/190,332 filed on Feb. 26, 2014. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a process of recovering useful materials from waste sources that include Dried Distillers Grains with Solubles also known by the acronym DDGS, waste materials from ethanol production and animal feed waste. 
     BACKGROUND OF THE INVENTION 
     Thin stillage and distillers&#39; grains are byproducts remaining after alcohol distillation from a fermented cereal grain mash. Both byproducts are used as energy and protein sources for ruminants. There are two main sources of these byproducts. The traditional sources were from brewers. However, more recently, ethanol plants such as corn, sugar cane, cassaya and potatoes have become a growing source. 
     DDGS contain valuable bio-materials mainly fibers, oil and protein. The oil in DDGS could be used either as cooking oil or as a biofuel. The main protein in corn is Zein which has been used in the manufacture of a wide variety of commercial products, including coatings for paper cups, soda bottle cap linings, clothing fabric, buttons, adhesives, coatings and binders, recently this protein has been used as a coating for candy, nuts, fruit, pills, and other encapsulated foods and drugs. Additionally Zein can be further processed into resins and other bioplastic polymers. Fibers may be used as raw materials in the production of lignocellulosic ethanol. Residue materials from ethanol production contain fibers from which ethanol has been extracted. However, only about 50-70% of the ethanol in these materials is typically extracted leaving substantial portion of ethanol that is available for further extraction. Tables 1 and 2 provide a typical content breakdown of the various materials in DDGS. 
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Cellulosic biomass compositional analysis of DDGS. 
               
             
          
           
               
                   
                   
                 Average 
               
               
                   
                   
               
             
          
           
               
                   
                 Dry matter 
                 88.8 
               
               
                   
                 Water extractives 
                 24.7 
               
               
                   
                 Ether extractives 
                 11.6 
               
               
                   
                 Crude protein 
                 24.9 
               
               
                   
                 Glucan (total) 
                 21.2 
               
               
                   
                 Cellulose 
                 16 
               
               
                   
                 Starch 
                 5.2 
               
               
                   
                 Xylan and Arabinan 
                 13.5 
               
               
                   
                 Xylan 
                 8.2 
               
               
                   
                 Arabinan 
                 5.3 
               
               
                   
                 Ash 
                 4.5 
               
               
                   
                 Total dry matter 
                 100.4 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Nutritional Compositional analysis of DDGS. 
               
               
                 Nutritional Compositional analysis 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Dry matter 
                 88.9 
               
               
                   
                 Crude protein 
                 27.3 
               
               
                   
                 Crude fat 
                 14.5 
               
               
                   
                 Carbohydrates 
                 53.5 
               
               
                   
                 Ash 
                 4.7 
               
               
                   
                 Total 
                 100 
               
               
                   
                   
               
             
          
         
       
     
     It would therefore be desirable to provide a process to separate these materials in order to maximize their uses. 
     SUMMARY OF THE PRESENT INVENTION 
     In an aspect of the present invention, a multi-stage substantially continuous process for separating a source stream said source stream intermixedly containing fibers, water, protein and oil, said process being configured for separating the source stream into streams each containing predominantly one component, said source stream containing dried distillers grains with solubles, said process comprises the stages of: providing a source stream comprising dried distillers grain with solubles, said dried distillers grain stream containing water, oil, protein and fibers; separating said source stream into a second stream and a third stream, said second stream containing predominantly fibers, said third stream containing predominantly a mixture of oil, protein and water, said separating being accomplished through the treatment of the first stream with; separating a fourth stream and a fifth stream from said third stream, said fourth stream containing predominantly water and said fifth stream containing predominantly oil and protein; and separating from the fifth stream a stream containing predominantly oil and a stream comprising predominantly protein through the steps of drying, size reduction, and pressing out the oil. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart schematic of the process according to an embodiment of the present invention; and 
         FIG. 2  is a flow chart schematic of the process according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention. 
     The main components of Raw Dried Distillers Grains with Solubles (DDGS) include water in the range of between about 70% to about 95%, but could also be higher or lower depending on the source. 
     It is desirable that the water content of the source DDGS stream be consistent in order for the process to be stable. Therefore, water is added as needed to ensure that the solids level in the DDGS entering the process does not exceed 30%. 
     The process consists of mechanical separation steps aided by polymeric additions to separate the DDGS into four streams each containing predominantly one component: fibers, water, oil and protein. 
     In the first step, the DDGS source stream is introduced into a rotary screen through a 1″ pipe. Between 5-25 ppm of a cationic polyamine having a 50% charge and a MW of about 800,000 are added to the pipe. This helps precipitate a stream that contains water and non-aqueous matter, predominantly fibers ranging in length from some 0.01″ to as long as 0.5 inches, and having a non-aqueous content of between about 25% and about 35%. This stream, labeled as the 2 nd  stream in  FIGS. 1 and 2  is passed through a press that squeezes fluid from this stream and concentrates it to between about 40% to about 50% solids. The fluid removed from the 2 nd  stream by the press contains water and some protein and oil. It is labeled as the 6 th  stream, and is further processed to separate any oil and protein from it. The press may be a multidisc press or a screw press; however other press types also fall within the scope of this invention. 
     It is noted that the term “contains predominantly” refers to a content of more than 50% in the context of the present invention. 
     The low solids stream exiting the rotary screen contains predominantly water at between 95 percent and 99 percent, and oil and protein at between 1 to about 5 percent. It is labeled as the third stream in  FIGS. 1 and 2 . The third stream is sent to a Dissolved Air Floatation device (DAF) where it is separated into a fourth stream containing predominantly water at &gt;99% and a fifth stream containing between about 75% to about 85% water and non-aqueous matter containing mostly protein and oil. Helping with the separation is polymer addition going into the pipe leading to the Dissolved Air Floatation device using the 2 nd  and/or 3 rd  inlets. If the pH of the third stream is lower than 5.5, between about 5 to about 25 ppm of a cationic acrylamide copolymer are added to the 2 nd  inlet as shown in  FIG. 1  which represents the schematic of the process for a DDGS stream having a pH&lt;5.5. If the pH of the third stream is greater than 5.5, between about 5 to about 25 ppm of anionic acrylamide copolymer having a MW of between about 18 million to about 24 million is also added to the 3 rd  inlet as shown in  FIG. 2  which represent the schematic of the process for a DDGS stream having a pH&gt;5.5. 
     The cationic acrylamide copolymer has a Molecular Weight of between about 8 million and about 19 million and between about 20 percent to about 40 percent charge. 
     The sixth stream may be combined with the fourth stream prior to entering the Dissolved Air Floatation device or combined with the effluent water in the fourth stream, depending on the oil and protein content of the sixth stream. 
     The 3 rd  inlet is set about 15 seconds below the second inlet calculated based on the average volumetric flow rate through the pipe. 
     Next, the fifth stream is passed through either a multidisc press or a screw press that separates out of the fifth stream a low moisture (&lt;30%) stream labeled as the seventh stream and a high moisture stream (&gt;40%) labeled as the 12 th  stream in  FIGS. 1 and 2 . The 12 th  stream is passed through a vacuum drum to reduce the moisture content of the 12 th  stream to between about 20 percent and about 30 percent. To aid in the water removal, about 5 to about 25 ppm of anionic acrylamide copolymer having a MW of between about 18 to about 24 million are added to the vacuum drum. The water removed from the vacuum drum is combined with the fourth stream and the combined water stream is treated with between about 5 to about 25 ppm of anionic acrylamide copolymer having a MW of between about 18 million to about 24 million in order to reduce the COD and BOD of the stream to dischargeable levels. The lower moisture stream exiting the vacuum drum is labeled as the 13 th  stream. 
     The seventh stream is passed through a dryer where most of the moisture is removed leaving a cake of protein and oil having relatively large material chunks generally from about 0.1 inches to about 0.3 inches. This cake is labeled as the eighth stream. Also entering the dryer is the 13 th  stream where it combines with the seventh stream. 
     The eighth stream is passed through a hammermill that reduces the particle sizes to generally less than 0.1″ thereby generating a ninth stream. The ninth stream exiting the hammermill is pressed to separate out a stream that is predominantly oil (10 th  stream) from the cake and leaving the cake with a predominantly protein content (11 th  stream). The predominantly oil stream is about 97% pure. The press may be a heated oil press or another type of press suitable for this step. Water vapor in a temperature range of between 60° C. and about 88° C. may optionally be injected prior to the dryer to preheat the seventh stream and increasing moisture uniformity in the stream. The tenth stream may further be filtered and any residual protein precipitated out with the aid of between about 5 ppm to about 25 ppm of a cationic polyamine having a 50% charge and a MW of about 800,000 to bring the purity of the tenth stream to around 99%. 
     The following represents the important characteristics of the polymers used in the process. 
     Polyamines 
     
         
         
           
             Molecular weight between 10,000 and 1,000,000. 
             Liquid form with 40 to 50% concentration. 
             Cationic site on the main chain. 
             Viscosity at 50% concentration of between 40 and 20,000 centipoises. 
             Any polyamine having two H 2 N groups may be used in this application. An example may be 1,3-diaminopropane.
 
Cationic Acrylamide Copolymers
 
           
         
       
    
                                
Sodium or Potassium Anionic Acrylate Acrylamide Copolymer.
 
     This polymer may be made from the reaction between an acrylamide monomer and an acrylic acid monomer as shown below. 
     
       
                 
         
             
             
         
      
     
     The anionicity of these copolymers can vary between 0% and 100% depending on the ratio of the monomers involved. The anionic copolymers used in the process of the present invention may have a molecular weight ranging between about 3 million to about 30 million, and a viscosity at a concentration of 5 g/l ranging from about 200 centipoises to about 2800 centipoises. The preferred pH range for making these copolymers is from 4.5 to 9. It is also noted that potassium may be substituted for the sodium as the base in the Acrylate Acrylamide copolymer. 
     It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention.