Abstract:
The invention relates to integrating at least two processes that use at least one acid, wherein one process utilizes an ion-exchange purification step.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to U.S. provisional application 60/353718, filed Feb. 1, 2002, which is herein incorporated by reference. 
     
    
     FIELD  
       [0002]     The invention relates to integrating at least two processes that use acid, wherein one process utilizes an ion-exchange purification step.  
       BACKGROUND  
       [0003]     The disposal of liquid waste that contains high concentrations of caustic and/or corrosive materials (ion-containing material) may cause serious environmental problems. Therefore, producers of such waste may take steps to either remove the caustic or corrosive material, or treat the material to convert it to less harmful compounds. Cost associated with the disposal of such waste reduces the profit that can be achieved from products that use caustic or corrosive materials in their production.  
         [0004]     Ion-containing materials are frequently used in processes employing ion-exchange purification. Products, such as, citric acid, itaconic acid, water, sugars and/or, sugar alcohols are purified using ion-exchange. Ion-containing materials are used to contact the ion-exchange resin and “recharge” the resin so that it can be repeatedly used to remove contaminants from the product.  
       SUMMARY  
       [0005]     The invention provides methods that use the same acid in multiple production processes (processes that give rise to distinct products), which reduces the overall cost of the acid (eliminates the need to purchase more than once), and reduces the overall disposal cost associated with the acid (need to dispose of less). Additional savings can be achieved when additional ingredients can be shared between the multiple production processes. For example, production processes that produce biomass and require ion-exchange purification can be coupled to processes that use biomass and one or more acids.  
         [0006]     For example, acids, such as HCl, H 2 SO 4 , or any strong acid, can be used to prepare glucosamine from chitin containing biomass, as well as from bacteria. The processes that produce glucosamine can be integrated with processes that utilizes ion-exchange technology, so that the acid can be used to generate a first product (for example, glucosamine) and then the acid can be used to regenerate an ion-exchange resin which is used to purify a product such as citric acid, bacterial produced proteins, etc. Hence, the acid is used at least twice to make two products, one product that requires treatment with acid and one product that requires ion-exchange purification.  
         [0007]     Accordingly, one aspect of the invention provides a process involving contacting an acid with biomass, wherein at least one first product is formed, then collecting such as by distillation, membrane separation, and/or chromatography, the acid and contacting the acid with an ion-exchange resin to regenerate the resin, wherein the ion-exchange resin is used to purify a second product.  
         [0008]     Another aspect of the invention provides using the biomass that produced the second product as a component of the first process (see  FIG. 1 ). Hence, both the biomass and the acid are used in both the first and second process.  
         [0009]     Specific examples of processes that can be coupled include organic acid production and glucosamine production. Additional benefits can be obtained by using caustic materials, such as, NaOH, NH 4 OH and/or KOH, that may be used to remove proteins from the biomass, to adjust the pH of acids used in the integrated processes. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a diagram that displays a general schematic illustration of a citric acid producing process coupled to a glucosamine producing process. The dotted line illustrates where these processes would be separated if they were not integrated.  
     
    
     DETAILED DESCRIPTION  
       [0011]     As described above, the disclosed processes integrate what were previously two separate processes together by using one or more of the same components in both processes. One of the shared components is an acid. Additional shared components can be biomass, water, and/or caustic solutions.  
         [0000]     Acids  
         [0012]     The acid can be any acid that is capable of forming a product, then being collected, and then used to regenerate an ion-exchange resin. Ion-exchange resins that may be regenerated include for example, Amberlite IR 120 (available from Rohm and Haas Co.), Duolite C-291 (available from The Dow Chemical Co.), Amberlite 200 (available from Rohm and Haas Co.), and Lewatit SP-112 (available from Bayer Ag.). As used herein “spent ion-exchange resin” refers to when the resin becomes loaded with charged contaminants to the point where unacceptable amounts of charged contaminants pass through the resin. One of ordinary skill in the art will appreciate that the acceptability of contaminant concentrations varies with the product being purified. Thus when the resin fails to remove the desired amount of charged contaminants it is termed “spent” and subjected to regeneration (described below).  
         [0013]     Typically, the binding capability of a particular resin is monitored by comparing the ion content of the effluent to the ion content of the feed. When the ion content of the effluent equals that of the feed the resin is said to be exhausted.  
         [0014]     The acid can be used first as a component in a first process and then used to regenerate the ion-exchange resin for a second process, or the acid can be used first to regenerate the ion-exchange resin, and then as a component in a second process. The acid can also be cycled through the first and second processes multiple times.  
         [0015]     When using HCl in a combined glucosamine/citric acid production process acid concentrations above about 1, 2, 3, 4, 5, 7, 10, 15, and 35% are desired to feed into the biomass process, and acid concentrations for regenerating the resin can range from about 4-10%.  
         [0016]     The acid is then recollected and its concentration may be adjusted (diluted for example by adding water, or concentrated for example by adding concentrated acid or removing water) to make it useful for regenerating the ion-exchange resin. Accordingly, if the acid is used to regenerate the resin first its concentration may need to be adjusted for use in the biomass treatment.  
         [0017]     The integration of the two processes can actually occur between two portions of a plant that are operated independently of each other (by separate parties). Furthermore, the acid can be additionally used in subsequent processes, for example the acid can also be used to regenerate ion resins that are used to purify water.  
         [0000]     Biomass  
         [0018]     Biomass as used herein refers to cells and byproducts made by cells (such as, intercellular organelles, nucleic acid, protein, cells walls, shells, and exoskeletons). Biomass can be derived from, for example, bacteria, yeast, fungus, plants, and shellfish. Biomass can be living, or dead. During many production processes live biomass is used to generate products, such as beer, citric acid, and/or pharmaceuticals. Generally, the living biomass eventually reaches a peak production level and then production of the desired product diminishes. The living biomass then becomes a waste product that needs to be disposed of. The remaining biomass material (cell bodies from fermentation or shells from shellfish) is then generally considered a waste product and sold as an animal feed or fertilizer.  
         [0019]     Both fungal biomass and bacterial biomass when treated with acid will yield glucosarnine, a beneficial dietary supplement and/or food ingredient. The fungal and bacterial biomass can be generated from citric acid production or lactic acid production, respectively.  
         [0000]     Integrated Plant  
         [0020]     A diagram that displays a general schematic illustration of an integrated plant for producing glucosamine and citric acid according is shown in  FIG. 1 .  
         [0021]     Fermentation of the fungal biomass occurs at  100 . The production of citric acid is generally depicted by a flow from  100  to  101  to  102  to  103  to  104 . Fungal biomass is removed at  101 . Cations are removed at  102  to partially purify the citric acid. Other impurities are removed at  103 , and the resultant citric acid is collected at  104 .  
         [0022]     The production of glucosamine is generally depicted by a flow from  400  to  401  to  402  to  403 . Hydrochloric acid is removed at  401 . Other impurities are removed at  402 , and the resultant glucosamine is collected at  403 .  
         [0023]     The fungal biomass removed at  101  is supplied via  202  as the microbial biomass for the production of glucosamine at  400 .  
         [0024]     The hydrochloric acid removed at  401  is supplied via  303  to regenerate the cation resin at  102 . After regenerating the cation resin, exhausted hydrochloric acid is removed at  606 .  
         [0025]     Specific details concerning pipes, valves, reaction vessels, and other engineering articles used to implement the embodiment of  FIG. 1  are not critical. For example, a valving arrangement can be used to control the flow of citric acid production at  102 . As a particular illustration, valves could be closed when the cation resin is spent to isolate the cation resin at  102  from section  101  and section  103 . Other valves could then be opened to allow flow of hydrochloric acid from  303  through  102  to  606  to regenerate the cation resin. It should be understood that other numbered areas, such as pipes, valves, reaction vessels, and other engineering articles, could be explicitly added to the diagram of  FIG. 1  to provide for flushes, rinses, purifications, and other routine engineering processes used to implement the embodiment of  FIG. 1 . However, after understanding the diagram of  FIG. 1  and the disclosure provided herein, one skilled in the art will easily envision such pipes, valves, reaction vessels, and other engineering articles to implement the invention.  
       EXAMPLE  
       [0026]     This example illustrates a general process for using biomass from citric acid production to make glucosamine, collecting the acid from glucosamine production, using the acid to regenerate an ion-exchange resin and then using the resin to purify citric acid.  
         [0027]     Biomass, from a citric acid fermentation process, was mixed with concentrated hydrochloric acid to form a mixture of 10 to 15 percent hydrochloric acid and 5 to 6 percent biomass, based upon dry weight of the biomass. The mixture was heated at reflux. Samples were taken from time to time, and the reaction analyzed with a high-pressure liquid chromatograph available from Dionex HPLC under the trade designation “DX-500.” Results indicated that glucosamine was produced.  
         [0028]     Following the reaction, the mixture was filtered. The filtrate comprised glucosamine and hydrochloric acid. The filtrate was evaporated using a rotating evaporator manufactured by RotaVap to increase the glucosamine concentration of the solution. The aqueous hydrochloric acid evaporate was then collected for reuse.  
         [0029]     After the citric acid solution flow has been redirected (is no longer flowing through the resin), the spent resin is regenerated using the recovered aqueous HCl. Regeneration is accomplished by feeding about 7% aqueous hydrochloric acid solution counter-current, or co-current, to the normal process flow into the resin to regenerate the resin. The hydrochloric acid is supplied as a uniform flow by a pump that controls the driving pressure for the regeneration flow. Typical amounts of regeneration flow range from 2 to 12 pounds of HCl per cubic foot of resin. Typical temperatures for the regeneration flow range from 100° F. to 135° F. Typical mass flow rates for the regeneration flow range from 2 to 10 resin bed volumes per hour. After flowing through the resin, the hydrochloric acid can be neutralized appropriately and sent to an appropriate sewer.  
         [0030]     After the above regeneration step, the 7% aqueous hydrochloric acid flow is stopped and acid remaining in the resin is displaced from the resin bed by water. This water flow is followed by a series of flushes or rinses to remove remaining acid.  
         [0031]     The cation resin of the column is now regenerated. It is ready to receive a new flow of citric acid containing solution, which again comprises citric acid, cation impurities, and other citric acid impurities.  
         [0032]     The processes described in the above example are representative of particular processes of the invention. The illustrated processes are intended to help explain the invention, but should not be considered limitations of the invention.