Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing oxygen-containing organic compound
Reexamination Certificate
2000-03-28
2002-05-21
Naff, David M. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing oxygen-containing organic compound
C435S200000, C435S201000
Reexamination Certificate
active
06391598
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods of recovering valuable components present in waste streams and effluents from anaerobic digestion systems, and more particularly comprises a partitioning method for recovering salts of volatile fatty acids, as well as undenatured enzymes in valuable forms.
BACKGROUND
The coexistence of small organic species, like acids and alcohols, with protein molecules is a common occurrence in various processing streams. For example, fermentation broths usually contain acids, vitamins and enzymes and are formed in conjunction with the manufacture of some industrially important proteins or in the cultivation of bacteria or fungi as extracellular components. Similar materials are found in the sera of animals and humans and as effluents in waste streams from meat processing streams, as well as in anaerobic digester effluents, (eg. from cattle rumens for instance), and all said examples present industry with a continuing disposal problem.
Further, it is known that said waste streams and anaerobic digester effluents typically contain components including valeric, acetic, propionic and butryic volatile fatty acids, and enzymes such as alpha-amylase and cellulase, as well as other proteins, many of which components are valuable and can be sold if available in separated-out, usable, form. And, as an added benefit, where such components are separated-out of waste streams or anaerobic digestion system effluents, the remaining waste or effluent can be easier to process to the point it can be disposed of, as the BOD requirement is often reduced.
As well, regarding waste streams or effluents such as are developed in meat processing plants, the recovery of useful chemicals therefrom, or their complete treatment is often mandated by local or federal regulations, (eg. where acetic and other carboxylic acids are present in the waste materials).
Beneficially, separation of valuable acids and/or enzymes can convert a waste stream into a value added stream and thereby create positive cash flow where otherwise disposal costs are required.
With the foregoing in mind, it is noted that adsorption combined with extraction, has long been the method of choice when other conventional separation methods prove too expensive and/or are energy intensive.
As described by Eyal and Canari in an article titled “Ph Dependence of Carboxylic and Mineral Acid Extraction by Amine-based Extractants: Effects of pKa, Amine Basicity, and Diluent Properties”, Ind. Engng. Chem. Res. 34:5 1789-1798 (1995); and by Ganguly and Goswami in an article titled “Surface Diffusion Kenetics in the Adsorbtion of Acetic Acid on Activated Carbon”, Sep. Sci. Tech. 31:9 1267-1278, (1996); adsorption and extraction are commonly used methods for the separation of acids from dilute streams.
Low molecular weight aliphatic carboxylic acids appear in many industrial and effluent streams and the recovery thereof by solvent extraction, with or without reaction, has been studied by Shama and Jagirdar and reported in an articel titled “Recovery and Separation of Mixtures of Organic Acids from Dilute Aqueous Solutions”, J. Sep. Proc. Technol., 1:2 40-43, (1980).
Amine-based extractants, because of their effectiveness and selectivity, are favored over other extractants in the recovery of acids from aqueous solutions as reported in an article titled “Extraction of Carboxylic Acids With Tertiary and Quaternary Amines: Effect of pH”, Yang et al., Ind. Engng. Chem. Res. 10:6 1335-1362, (1991).
Partitioning studies of various organic compounds using both adsorbents and extractants have also been documented by King in an article titled “Acid-base Equilibria” in the encyclopedia of Physical Chemistry and Chemical Physics, Pergamon Press, Oxford (1965); and in an article titled “Coupling Ion Pair Extraction With Adsorbtion for the Separation of Acidic Solutions for Water”, Payne and Ramarkrishnan, Ind. Eng. Chem. Res., (1995).
Adsorbents are generally employed in separations using column liquid chromatography for proteins and other organic solutes. Adsorption of molecules of different sizes and surface charges has been investigated by Tien in an article titled “Adsorbtion Calculations and Modeling”, Butterworth-Heinemann, Mass. (1994).
Recently amine-based experiments to extract and recover alpha-amylase from reverse micellar solutions has been reported by Chang and Chen titled “Purification of Industrial Alpha-amylase by Reversed Micellar Extraction”, Biotech, Bioengng, 48, 745-748, (1995).
It is noted that a use for salts of (APB's) is as de-icers as discussed in an article titled “Chemical Deicers and the Environment”, D'Itrl, Lewis Publishers, Mich., (1992).
Further, commonly utilized de-icers are more corrosive than are esters, such as an acetate, as reported by Reisinger and King in an article titled “Extraction and Sorbtion of Acetic Acid at pH Above pKa to form Calcium Magnesium Acetate”, Ind. Sep. Proc. Technol., 34, 845-352, (1995), hence use of metal esters such as CaMg Acetate, CaMg Propionate etc. can be projected as providing environmentally friendly results.
It is specifically noted that for any dilute aqueous stream which contains acids and enzymes, the operating parameters for separating out the acids are different than those for recovering the enzymes and importantly, successful simultaneous separation of both acids and proteins has not before been reported. The present invention, however, teaches that uptake of carboxylic acids and enzymes, alpha-amylase and cellulase from solution can be achieved, where the enzymes are preferentially sequestered, either by leaving the acids in solution or by partitioning the acids into a different phase. And, since unlike solutes do not compete simultaneously with the non-aqueous phase (organic or solid), high percentage separations for acids and enzymes can be achieved.
Present invention experimental work has focused on acetic, propionic and butyric acids and protein compounds including alpha-amylase arid cellulase, (which enzymes are industrially important in degradation of starch and cellulose, respectively), but the approach of using an organic extractant and solid adsorbent to simultaneously separate acids and enzymes is applicable to other systems.
The principal advantage of using organic extractant and solid adsorbent to simultaneously separate acids and enzymes is the ease with which these phases can be separated from an aqueous phase. The extractant and solid phases can be separated from the aqueous phase and the respective phases can be stripped of solutes, allowing the process to be made continuous.
If one solute shows a distinct affinity towards an adsorbent/extractant in the presence of other solutes, then it can be recovered initially.
A Search of Patents has provided a Patent to Monick et al., U.S. Pat. No. 4,765,908 which describes a process and composition for removing contaminants from wastewater. Many chemical compositions are identified for removing heavy metals such as Sodium and Calcium Bentonite, Montmorillonite, calcium carbonate, calcium oxide, calcium hydroxide, lime, aluminum sulfate and a catalist, zirconium. Recovery of enzymes is not a focus.
U.S. Pat. No. 4,675,114 to Zagyvai et al., describes a process for dewatering sludges containing proteinic organic contaminates and for separating solid particles from the aqueous phases. The use of calcium hydroxide and/or magnesium oxide to produce an alkaline sludge pH is mentioned. The use of formaldehyde is described and the methodology does not focus on sequential removal of enzymes followed by removal of other elements.
U.S. Pat. No. 4,629,785 to McCaffery, III, describes a procedure in which proteinaceous material is separated from cationic species by an adsorption process. Converting active microorganisms to inactive form is disclosed.
U.S. Pat. No. 2,171,198 to Urbain et al., describes use of Zinc Oxide to remove and recover fatty acids from waste.
U.S. Pat. No., 3,738,933 to Hollo et al., describes a process for recovering protein from sewage which uses bentonite or kaolin
Clements L. Davis
Koppolu Ajoy Y. K.
Board of Regents of the University of Nebraska
Meller Mike
Naff David M.
Welch James D.
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