EP1137481A1

EP1137481A1 - Method for the purification and recovery of waste gelatin

Info

Publication number: EP1137481A1
Application number: EP99958995A
Authority: EP
Inventors: William J. Schmidt
Original assignee: A B Technologies LLC
Current assignee: A B Technologies LLC
Priority date: 1998-11-16
Filing date: 1999-11-15
Publication date: 2001-10-04
Also published as: EP1137481A4; KR100674488B1; CA2350746C; JP2002529589A; AU1625700A; WO2000029097A1; KR20010093082A; AU760327B2; CA2350746A1

Abstract

Method and apparatus for treating a waste material containing gelatin in which the waste material stream (5) is combined with a solvent stream (2) which is capable of dissolving the gelatin and any softening agent contained therein and then treating the resulting product to obtain a recoverable and usable gelatin containing stream exiting receiver (34) and any components contained in the original waste stream.

Description

METHOD FOR THE PURIFICATION AND RECOVERY OF WASTE GELATIN

Field of the Invention

This invention is generally directed to a process for recovery, purifying and

recycling gelatin waste made from gelatin and derivatives thereof and in particular, to

a process for recovery, purifying and recycling gelatin waste, its derivatives, and

components contained within gelatin waste resulting from industrial encapsulation

processes.

Background of the Invention

Gelatin and gelatin derivatives are used to encapsulate the products of several

industries. Examples are described in U.S. Pat. No. 5,074,102, issued to Simpson et

al, and include the encapsulation of medicinal compounds such as drugs and vitamins;

employment of gelatin encapsulation in food packaging, such as for powdered instant

coffee or spices; in candy manufacturing; in fertilization of ornamental plants and/or

indoor plants; in packaging of sensitive seeds in combination with protective agents

and/or fertilizers; and in the packing of single dyestuffs or mixtures of various drugs.

In each of the above-recited manufacturing and production processes, a certain

amount of the encapsulating material and the encapsulated material (e.g. vitamins) is lost as waste. Frequently, the amount lost as waste of the encapsulating material

approaches 50% or more of the total starting material, depending on the arrangement

of production employed. When considering that the cost of the encapsulating material

in the United States averages approximately $3.10 per pound ($6.82 per kilo) as of

September, 1997, it is clear that the economic consequences of such waste can be

significant. As a result, manufacturers have attempted to off-set poor production

efficiency by recycling the waste material for reuse. Such attempts, however, have not

been met with a great deal of success.

Prior art methods of gelatin recovery and purification suffer from a variety of

shortcomings to be discussed in further detail below. Before these shortcomings can

be fully appreciated, however, the composition of the encapsulation waste material itself

should be further understood. In general, waste material of encapsulation processes

is comprised of a variable number of components added to a gelatin base. Among

them are solvents (usually water); softening agents and oil coatings (when desired);

and, contaminants in the form of residual active ingredients, i.e. the substance being

encapsulated. In addition, colorings and preservatives may also be added. Thus, it can

be observed that successful recycling involves not only the recovery of gelatin from

surrounding oils, but also the removal of the remaining components of the waste in

order to achieve a relatively pure, reusable product. Extraction has been the principle method for accomplishing removal of oils,

actives and the like in the pharmaceutical industry. While several solvents have been

used in the prior art in an effort to accomplish separation, each suffer from a variety of

shortcomings not the least of which is the necessity of ultimately removing yet another

component, i.e. the solvent itself, from the recycled materials. To date, the most

popular and widely used solvents used to separate gelatin from oils and actives are

chlorinated solvents such as, for example, 1 ,1 ,1 ,-trichloroethane with naphtha. The use

of chlorinated solvents, however, is accompanied by high costs, disposal problems, and

most importantly, environmental concerns. Attempts have been made to use other

solvents including isopropyl alcohol, methyl isobutyl ketone, toluene, hexane, heptane,

acetone, and acetone/water mixtures, but the resulting yields are insufficient and/or the

separation is poor. Furthermore, some of these chemicals are relatively expensive and

present similar environmental, disposal, and safety concerns as the chlorinated

solvents. None of them have been found to separate oils and actives with a high

degree of efficiency.

U.S. Patent No. 5,288,408, issued to Schmidt et al, discloses a method of

recycling gelatin-based encapsulation waste material, and more specifically, to a

process for the recovery and purification of gelatin and softening agents therefrom. In

the preferred embodiment, deionized water is added to the waste material thereby

forming an aqueous solution of gelatin and glycerin dispersed within the remaining oil

and residual active-ingredient components of the waste material. Extraction methods are employed under specific conditions to effect separation of the lower aqueous phase

from the upper oil phase. The lower phase is hot filtered to remove any remaining

traces of oil or other contaminants and the filtrate is then charged to a concentration

vessel adapted for vacuum distillation. The water solvent is thus removed under

specific thermal and atmospheric conditions until the desired concentration of gelatin

and glycerin is achieved. A pure, concentrated aqueous gelatin-glycerin solution results

which may be stored or further prepared for immediate reuse. Although this process

lends itself to the removal of dyes and active ingredients with additional chemical

reactions and processing, such dyes, active ingredients, and glycerin are not removed

in situ.

Clear gelatin contains no dye, colorants or the like. It is used to make clear

gelatin capsules in the pharmaceutical, neutraceutical, and nutrient industries and other

industries as well. Because dyes are not present, there is a need to provide a cost

efficient and effective manner for recycling the gelatin and glycerin for reuse. Gelatin

may have suspended particles such as titanium dioxide which impart a color to the

gelatin. Such particles can be more easily removed from the waste gelatin than dyes

and colorants which are water soluble.

It would, therefore, be desirable to provide a method for recycling gelatin-based

encapsulation waste material that recycles gelatin and glycerin in situ without the need

for any additional processing. It would be a further advance in the art of recycling waste gelatin if an in situ process could be developed that is especially effective in recycling

gelatin and gelatin containing suspended particles without thermal degradation in a cost

efficient and effective manner. It would be a still further advance in the art to provide

a cost efficient and effective method of recycling gelatin whether clear or colored and

whether or not the gelatin contains suspended particles (e.g. a colorant).

It would be a still further advance in the art to provide a method of recovering

valuable components from a waste gelatin recovery process.

Summary Of The Invention

The present invention is generally directed to the recovery of waste gelatin alone

or in combination with other components of a waste gelatin product through the

separation and treatment of a waste gelatin stream into an aqueous and non-aqueous

substream.

In one aspect of the present invention there is provided a method of treating a

waste material containing gelatin comprising:

a) combining the waste material and a solvent for the gelatin to form a liquid

containing gelatin;

b) separating the liquid into a solvent based phase or layer and a non-

solvent based phase or layer; and c) removing residual oils and/or particulates from the solvent based layer to

form a second liquid containing gelatin having a higher purity than the first liquid.

If desired, the second liquid may be concentrated by removing at least some of

the solvent, solvent soluble active ingredients, softening agent, dyes and other solvent

soluble impurities to provide at least a substantially purified second liquid.

Brief Description of the Drawings

The following drawings in which like reference characters indicate like parts are

illustrative of embodiments of the invention and are not intended to limit the invention

as encompassed by the claims forming part of the Application.

Figure 1 is a schematic view of an embodiment of the method of gelatin recovery

and purification in accordance with the present invention; and

Figure 2 is a schematic view of a further embodiment of the invention similar to

Figure 1 in which a separate, external degassing operation is provided to remove

dissolved gases (e.g. air) from the recovered gelatin. Detailed Description Of The Preferred Embodiments

Gelatin is a protein derivative of collagen obtained, in general, by the boiling of

skin, white connective tissues, and bones of animals, and by the partial hydrolysis of

collagen, in particular. As a colloid it has unique physical properties. Of particular

significance to the present invention is its tendency to stay in solution and its ability to

form dispersions in oils. Gelatin remains a solid at standard atmospheric pressure and

temperature absent the presence of a sufficient quantity of solvent.

Softening agents are sometimes added to plasticize the gelatin when soft, gelatin

shells are desired. Agents such as glycerin, sorbitol, or other similar polyols are

commonly employed as softening agents. Glycerin is a preferred softening agent.

The soft elastic capsule-forming material may be used to enclose active

components in the form of powders, liquids, or combinations thereof. Oils, such as

vitamin A, vitamin E, and beta-carotene, for example, are frequently encapsulated by

such soft gel materials in the pharmaceutical, cosmetic, and nutritional industries.

Additionally, other oils like mineral oil or medium chain triglycerides (MCT's) may be

used to coat the outer surface of the gel-capsule during processing. Thus, it can be

seen that the waste product of the encapsulation process may have, in addition to

gelatin and a softening agent such as glycerin, many components (e.g. oily

components) which must be removed before the gelatin waste is available for reuse as a relatively pure product. In some instances, coloring agents and preservatives may

also be incorporated into the gelatin mass. Commonly used preservatives include

methylparaben, propylparaben, and sorbic acid.

Present methods of encapsulating active components employ a ribbon or sheet

of gelatin which is then die punched to form capsules. As much as 50% or more of the

gelatin starting material (i.e. gelatin ribbon) is either discarded as a waste by-product

or recycled. The latter option requires the removal of all of the above-mentioned

components. The present invention provides a novel and efficient method of purifying

and recycling the waste material without experiencing the shortcomings of the prior art.

It will be understood that other proteins with ; hysical and chemical properties similar

to gelatin exist and may also be recycled by the present process. Similarly, glycerin is

only one example of a softening agent which may be recovered; thus, neither gelatin

nor glycerin are intended to be limiting.

Reference is now made to Figure 1 wherein an embodiment of the present

invention for the purification and recovery of gelatin and/or glycerin is illustrated. A

suitable solvent such as deionized (D.I.) water is added through a conduit 2 in an

amount sufficient to dissolve the waste gelatin material, typically in an amount of up to

about five volumes, based on the quantity of waste gelatin, preferably from about 0.5

to 5.0 volumes is added to a dissolution/separation vessel 4 which may be provided

with a heating jacket known in the art. The solvent is preheated to a temperature of from about 30 to 70°C to make the waste gelatin in a convenient flowable condition. The

waste gelatin material is then charged either batchwise or continuously to the

dissolution/separation vessel 4 via a conduit 5 which may be made of stainless steel

or glass-lined construction and sized according to a desired batch size. The

dissolution/separation vessel 4 may also be provided with a conventional agitation

device such as a stirrer (not shown). The waste material to be recovered is diluted with

the solvent (e.g. deionized water) typically at atmospheric pressure under heating at a

temperature from about 30 to 70^°C to a preferred concentration of from about 8% to

45% gelatin by weight. Agitation is simultaneously performed to effect dissolution of the

gelatin and the softening agent (e.g. glycerin).

A solution of gelatin and glycerin [i.e. solvent based layer (e.g. aqueous layer)]

is thus formed within the remaining oily component and residual active-ingredient

components [i.e. non-solvent based layer (e.g. non-aqueous layer)]. As used herein

the term "solvent based layer" shall mean a layer or phase in which the components

contained therein are dissolved in the solvent. The term "non-solvent based layer" shall

mean a layer or phase in which the components therein do not dissolve in the solvent

and therefore may be separated from the solvent based layer. Since water is the

preferred solvent, reference will be made hereinafter to the aqueous layer and non-

aqueous layer. The above recited concentration level of gelatin (from about 8% to 45%) is a

preferred concentration for achieving rapid and thorough separation of the upper non-

solvent based layer (e.g. non-aqueous layer) from a lower solvent based layer (e.g.

aqueous layer). The upper non-aqueous layer is either discarded or sent via a conduit

6 to a recycling system 8 which is known in the art. If recycled, the non-aqueous layer

may be separated into oily components including, but not limited to, vitamins (for

vitamin containing products (e.g. vitamin E)), mineral oil, garlic oil, fish oil, beta

carotene, and vitamin E, which emerge through conduit 10.

Once the gelatin is completely dissolved within the vessel 4, agitation is

terminated and the mass is allowed to either 1 ) stand to effect separation of the solvent

based layer (e.g. aqueous layer) from the non-aqueous layer then further processed to

remove residual oils and/or particulates or, 2) alternatively, the entire mass may be sent

directly to an appropriate apparatus for separation of the aqueous and non-aqueous

layers.

If the mass is allowed to stand to effect separation of the oils, it has been

observed that for a batch size of about 150 Kg, for example, approximately 1 to 3 hours

were required for separation. Separation of the lower aqueous layer from the upper

non-aqueous layer within the vessel 4 can be facilitated by a sight glass incorporated

into the recycling system 8. Accordingly, differences between the two layers are

visually determined to effect accurate separation. Alternatively, an oil skimmer may be employed to remove the non-aqueous layer, as previously indicated, which is discarded

or further processed in the recycle system, while the lower aqueous layer is further

processed as discussed below.

The separation and recovery of the individual oily components within the non-

aqueous layer of the recycling system can be accomplished by a variety of processes

including, but not limited to, fractional distillation, short path distillation, and reverse

osmosis.

In general, distillation is a process in which a liquid is vaporized, recondensed,

and collected in a receiver. The liquid which has vaporized is collected in a receiver.

The resultant liquid (i.e. condensed vapor) is referred to as the condensate or distillate.

Distillation is a process for purifying liquids by separating the liquid into its

components. It is based on the difference in the volatility of the liquids. Volatility is a

general term used to describe the relative ease with which molecules (liquid or solid)

may escape from the surface to form a vapor. The vapor pressure of a liquid is related

to the ease with which the liquid volatilizes (i.e. a relatively volatile substance exerts a

relatively high vapor pressure at room temperature). The more volatile a substance,

the higher its vapor pressure and the lower its boiling point. Fractional distillation is the separation and purification, by distillation, of two or

more liquids into various fractions. It is a systematic redistillation of progressively purer

distillates or fractions. A fractionating column is used to essentially perform a large

number of successive distillations without the necessity of actually collecting and

redistilling the various fractions. A fractionating column may be packed with glass

beads, glass helices, metal screens or ceramic saddles to effect fractionation.

A series of distillations involving partial vaporization and condensation

concentrates the more volatile component in the first fraction of distillate and the less

volatile component in the last fraction or in the residual liquid. The vapor leaves the

surface of the liquid and passes up the packing of the column. The vapor condenses

on the cooler surfaces and redistills, typically many times before entering the

condenser. By means of long and efficient distillation columns, two liquids may be

completely separated.

Short path distillation is especially suitable for substances that cannot be distilled

by any of the ordinary distillation methods because (1) the substance is viscous, and

any condensed vapors tend to plug the distilling column or condenser; and/or (2) the

vapors of the substance are extremely susceptible to condensation.

Short path distillation differs from other distillations because (1) a condensed

vapor flows to the distillate receiver or collector; (2) very low pressure (high vacuum) in the system favors vaporized molecules reaching the condensing surface without

collision with other molecules to condense prematurely; (3) there is a very short

distance between the surface of the evaporating liquid and the condenser surface; and

(4) the substance has a residence time in the presence of heat which is very short so

that thermal degradation is prevented.

A short path distillation apparatus typically includes a rotating still. Materials are

fed into the rotating still and distributed evenly and thinly over a heated evaporating

surface. The substance distills in a short time and the vapors condense and run into

a collector. The degree of vacuum is controlled to collect the distillate effectively at the

condenser. The pressure can be as low as 1 μm Hg.

Short path distillation as described herein is also known as molecular, wiped film,

thin film, falling film, and rising film distillation. Short path distillation systems are

commercially available from companies such as Pope Scientific in Saukville, Wl and

Artisan Industries in Waltham, MA.

Reverse osmosis is a process whereby dissolved solids or a miscible liquid are

removed from water by applying a pressure differential across a semi-permeable

membrane. The semipermeable membrane allows water to flow therethrough, but does

not allow other components from passing through the membrane. Reverse osmosis equipment is commercially available from companies such as Pall Filtron in

Northborough, MA and Millipore Corporation in Bedford, MA.

As described above, the dissolved gelatin is separated into a solvent based layer

(e.g. aqueous layer) and a non-solvent based layer (e.g. non-aqueous layer). The non-

aqueous layer is then treated by any of the above described methods to recover the oils

contained in the non-aqueous stream.

If the separated aqueous layer contains particulates and/or oily type materials,

the aqueous layer may then be treated, to remove residual oils and/or particulates

preferably by means of hot filtration processes as more fully described below.

The aqueous layer is sent through a heated transfer conduit 14, to a hot filtration

assembly 18. The hot filtration assembly 18 is particularly desirable if the aqueous layer

contains particulate matter or residual oil matter.

The method of hot filtration employed for the removal of oils and/or particulates

may include, but is not limited to, techniques such as liquid:liquid centrifugation, sub-

micro/micro-filtration, liquid.liquid coalescers, absorbents and filter aids such as, but not

limited to, diamataceous earth, activated carbon, clay or activated clay, colloidal silica,

porous acrylic resins and the use of oil soluble salts to break any emulsion that may

exist. Liquid:liquid centrifugation is based on the principal that the rate of separation

of two immiscible liquids is increased significantly by the application of centrifugal force

which can be thousands of times that of gravity. The force exerted on the liquids is

directly proportional to the speed of rotation, the radius of rotation, and the mass of the

liquids.

The force exerted on rotating immiscible liquids, i.e, aqueous and non-aqueous

liquids, is described in terms of relative centrifugal force or number of g's which is

expressed as multiples of the force of gravity. Centrifuges are rated by their relative

centrifugal force which can typically range from 10 to hundreds of thousands. Relative

centrifugal force can be controlled by varying the speed or the centrifuge head or rotor.

As a method of hot filtration in the subject invention, the aqueous layer to be hot

filtered is maintained at a temperature sufficient to allow flow into the centrifuge; higher

temperatures and/or higher dilutions may also enhance an efficient separation by

reducing the viscosity of the liquids to be separated. A temperature of from about 30°C

to 70°C and a dilution volume of up to 5 volumes, preferably from about 0.5 to 5

volumes of a suitable solvent, such as water, is preferred.

The efficiency of separation may be enhanced by employing a relatively higher

centrifugal force in the range of from about 5,000 to 25,000. The resulting, clarified

aqueous layer containing gelatin and glycerin is collected for reuse and the residual oils and/or particulates are either discarded or collected for potential recovery as discussed

hereinafter.

Liquid:liquid:solid centrifugation can also be utilized to achieve separation of the

gelatin and softening agent (e.g. glycerin) from the particulates and/or residual oils.

This procedure is preferred when the waste gelatin stream contains particulates which

are at least a part of the coloring system (e.g. titanium dioxide).

Commercial liquid:liquid and/or liquid:liquid:solid centrifugation equipment is

available from companies such as Westfalia Separator U.S. in Northvale, NJ and Alfa

Laval in Warminster, PA.

Micro or sub-micro filtration refers to a method of removing small particles from

a liquid. Particulates as used herein include, but are not limited to, solid particulates

which do not have sufficient mass to settle out of solution and/or emulsions and micro-

emulsions which do not readily separate from a liquid. Micro or sub-micro filtration can

be achieved through the use of micron or sub-micron pore sized filters including, but not

limited to cartridge type filters, also known as "depth" or "dead end" filters and

tangential flow type filters. Tangential flow type filters are the preferred filters for this

purpose. The pore size of the preferred filters is typically in the range of from about 0.1

and 2.0 microns. Temperature and dilution are important considerations in improving the efficiency

of the filtration process by varying the viscosity of the liquid. A temperature of from

about 30°C to 70°C and a dilution volume of up to 5 volumes preferably from about 0.5

to 5 volumes of a suitable solvent, such as water, is preferred.

Micro or sub-micro filtration equipment is commercially available from suppliers

such as Millipore Corporation in Bedford, MA.

A liquid:liquid coalescer, may be used to remove residual oils from the aqueous

layer. The coalescer enhances the collection of the oil droplets (the dispersed phase

liquid) into larger droplets which will separate more easily from the aqueous layer (the

continuous phase liquid).

Generally, for the subject application, a multiple stage system may be employed.

Such systems remove the designated materials in stages such as by first removing

particulates. Once the particulates are removed the remaining liquid may then be

treated with a coalescer to remove residual oil from the aqueous gelatin and glycerin.

A temperature of from about 30°C to 70°C and a dilution volume of typically up to 5

volumes, preferably from about 0.5 to 5 volumes of a suitable solvent, such as water,

is desirable. Commercial coalescers are readily available such as those supplied by

Millipore Corporation in Bedford, MA. Filter aids containing diatomaceous earth can be employed for removal of

particulates and/or residual oils. Diatomaceous earth, more commonly known as Celite

or Filter Aid, is a very pure and inert material which forms a porous film or cake on a

filter medium such as, but not limited to, filters made from paper, nylon and

polypropylene as are typically used in filtration systems using filtration apparatus such

as, but not limited to Nutsch filters, Rosenmund filters and/or centrifuges.

Diatomaceous earth can be employed: 1 ) by forming a slurry with an appropriate

solvent, such as water, then filtering the slurry through an appropriate apparatus, such

as a Nutsch or Rosenmund type filter, or a plate/coated plate filter such as a sparkler

filter, to form a thin film or cake or 2) by adding the diatamaceous earth directly to the

product to be filtered to form a slurry which is then filtered forming a porous thin cake

or film. A temperature of from about 30°C to 70°C and a dilution volume of up to 5

is desirable. Other filter aids besides diatamaceous earth include, but are not limited

to silica, acrylic resins, clay and activated carbon.

Absorbents which may be used to treat the solvent based layers include zeolitic

materials.

In particular, the lower aqueous phase may be heated, preferably hot filtered in

the filtration assembly 18 if particulates and/or residual oils are present at a temperature of approximately the same as above (i.e. from about 30°C to 70°C) preferably through

liquid:liquid centrifugation or micro/sub-micro filtration as described above to remove

any remaining traces of oily components or other contaminants through a conduit 20

and optionally forwarded to the recycling system 8 . Other types of filtration equipment

which may be employed include plate filters, or coated plate filters like, for example, a

sparkler filter. The preferred material of construction for these type of filters is stainless

steel. Alternatively, nutche filters of the Rosenmund type or cartridge filters may be

used for the purpose.

The employment of the hot filtration systems mentioned above separates

particulates and/or oils from the aqueous layer containing gelatin and the softening

agent (e.g. glycerin).

Depending on the concentration of the gelatin and glycerin in the resulting

filtrate, the filtrate may be returned directly to gelatin mass manufacturing or the filtrate

may be transported via heated conduit 22 to a concentration assembly 16 which may

be in the form of a diafiltration assembly and concentrated by removing some of the

solvent (e.g. water). For solutions having a gelatin concentration greater than about

10% gelatin wt/wt (e.g. 10% wt wt to 45% wt/wt), the aqueous solution may be charged

to a concentration apparatus adapted for vacuum distillation such as disclosed in

Schmidt et al., U.S. Patent No. 5,288,408, or to a diafiltration system such as disclosed

in Schmidt U.S. Patent No. 5,945,001 each of which is incorporated herein by reference. Alternatively, the filtrate may be subjected to short path distillation as

previously described.

Short path distillation for this aspect of the present invention is carried out under

controlled conditions to facilitate the removal of water at a lower temperature to prevent

thermal degradation of the recoverable gelatin. Evaporator temperatures typically from

about 50°C to 120°C, and typically pressures 20 to 30 in. Hg, preferably 22-28 in. Hg

are employed to remove water. Such temperatures and short contact time do not

cause decomposition of the protein-based gelatin which affects its bloom strength. The

water distillate is passed through a condenser to waste or recycle. The residue

contains the gelatin/glycerin mixture for reuse.

As an example, waste gelatin material is diluted with solvent (e.g. water) at a

ratio of 3:1 , wateπwaste gelatin material, the following illustrates the distillate:residue

ratios which may be via the chosen distillation process, to achieve a desired level of

recycled gelatin and glycerin.

To achieve a 25% recycle level for gelatin and glycerin from the above described

3:1 dilution, the distillation should preferably result in a distillate: residue ratio of 50:50.

To achieve a 40% recycle level for gelatin and glycerin from the above described 3:1

dilution, the distillation should preferably result in a distillate: residue ratio of 62.5:37.5.

In both examples the residue contains the gelatin and glycerin for recycle. Diafiltration may be employed at the concentration assembly 16 to remove

residual water soluble active ingredients, glycerine, water, and other water-soluble

components such as preservatives and dyes and to provide gelatin in a form that is of

sufficient purity and quality to permit reuse.

Diafiltration is a technique using ultrafiltration membranes to remove or

fractionate different size molecules in macromolecular solutions. An ultrafiltration

membrane retains macromolecules that are larger than the nominal molecular weight

limit (NMWL) of the membrane and freely passes molecular species which are

significantly smaller than the NMWL of the membrane. Macromolecules retained by the

membrane are concentrated, while the low molecular weight species are removed.

Typically, the macromolecules must be "washed" using multiple wash volumes to

remove residual smaller molecules, hence the name diafiltration (i.e. filtration using

ultrafiltration membranes and washing).

For continuous diafiltration, a supply of macromolecules (e.g. gelatin) is added

via the conduit 22 to the diafiltration assembly 16 at the same rate as the filtrate is being

removed. This is also referred to as constant volume diafiltration. The concentration

of the macromolecules does not change during the diafiltration process.

Discontinuous diafiltration involves first concentrating the macromolecule (e.g.

gelatin) batch to a predetermined volume, and then reconstituting the sample to its original volume with replacement solvent. This is repeated until the smaller molecules

are removed.

Referring to Figure 1 diafiltration may be accomplished by first heating the

system from about 50^°C to 65^°C by recirculating heated, deionized water typically for

about 15 minutes through the conduit 24. The hot, aqueous feed stream is then

pumped through fhe assembly 16 via a conduit 22 and concentrated to the desired

gelatin/water concentration as discussed hereinafter. When the desired water/gelatin

concentration is achieved, fresh, hot (e.g. from about 50 to 65°C), deionized water is

fed into the system at exactly the same rate as the effluent exiting the system; the

effluent being water and all water soluble components. Once the water soluble

components have been removed, the remaining gelatin/water solution is recycled for

gelatin encapsulation.

The filters that can be employed in the concentration/diafitration step are known

and available in the art. Such filters include screen filters including open channel filters

and the like. The selection of a suitable filter for the purification of gelatin must be

capable of separating gelatin (typically having a molecular weight of from about 30,000

to 50,000) from smaller molecules.

The recovered aqueous gelatin solution is concentrated to a final solids (gelatin)

concentration of at least between about 20% by weight, preferably from about 30% and 50%. The remaining concentrated gelatin is then purified using between about 1 and

20 diafiltration volumes of water, preferably between about 3 and 10 diafiltration

volumes to provide recovered gelatin that is sufficiently pure to permit reuse and which

leaves the diafiltration assembly 16 via a conduit 26 to a receiver 34. A portion of the

purified recycled gelatin may be sent back to the gelatin dissolving step via a conduit

28 to remove additional impurities from the gelatin to thereby obtain an even purer

product.

Impurities such as dyes, actives, water, preservatives and glycerine can be

removed from the diafiltration assembly via conduit 30.

Recovery of the above-mentioned impurities obtained from the diafiltration

assembly 16 via the conduit can be performed in a recycling system 32. This system

can be based on distillation systems including fractional distillation, short path distillation

and reverse osmosis as previously described in connection with the recycle system 8.

Fractional distillation and reverse osmosis are preferred for recovery of the stream 30

with reverse osmosis being the most preferred method.

The process stream 30 in addition to containing the above mentioned impurities

may contain from about 1 % to 10% by volume of glycerol in water, typically from about

3% to 7% by volume. The process stream 30 is treated at temperature of from about

0°C to 30°C, more typically from about 5°C to 20°C. Typically recovery of glycerol is at least 65% by volume, more typically from about 65% to 95%, most preferably from

about 80% to 95% by volume.

In some instances, dyes and pigments that are used to color gelatin capsules

have an affinity for the gelatin in the waste stream. Recovery of the gelatin alone may,

therefore, require that steps be taken to eliminate this affinity so that the dyes can be

removed. In general, it is necessary to take these steps following the hot filtration

process and prior to the concentration/diafiltration process.

Suitable methods for eliminating the affinity between dyes and/or pigments and

the gelatin include use of, for example, activated clay, carbon cartridge filtration; carbon

slurry formation followed by filtration to remove the carbon; pH adjustment to eliminate

adhesion of the dye to the gelatin, followed by direct diafiltration to remove the dyes,

and then adjustment of the pH back to the normal processing pH (e.g. from about 5 to

7); or, a combination of these methods.

If an affinity exists between the dyes and/or pigments, once the affinity has been

eliminated, diafiltration can be performed to obtain recovered gelatin. Alternatively,

diafiltration itself will remove these dyes and/or pigments with sufficient diafiltration

volumes. It is understood that the recycling system described can be incorporated into

a conventional encapsulation apparatus to provide repeated or continual recycling of

waste encapsulation materials. Entrapped air may be a consideration during the process of manufacturing

gelatin mass for encapsulation into soft gelatin capsules. General practice in the soft

gelatin capsule manufacturing industry is to manufacture the gelatin mass under

vacuum, for the express purpose of removing air, on a mezzanine or second floor then

feed the molten gelatin mass, by gravity, to the encapsulation machines on the first

floor.

In the absence of a building configuration conducive to gravity feed to the

encapsulation machines, gelatin mass can be transferred by air pressure or pumps.

The choice of pump must be such that as little air as possible is introduced into the

gelatin mass. Examples of appropriate pumps may be, but are not limited to, peristaltic,

moyno, and sine type pumps.

The ultrafiltration process of the present invention can generate flow rates in

excess of 200 liters per minute. Although proper engineering and design of the

diafiltration system will minimize or eliminate introduction of air from external sources,

the flow rates generated may nonetheless, introduce some air into the gelatin. The air

can be entrapped or dissolved in the viscous gelatin mass. Under these circumstances,

it is desirable to degas or remove at least most of the air from the gelatin.

Typical practices in analytical chemistry for degassing dissolved air in water

and/or organic solvents used as a mobile phase for High Performance Liquid Chromatography (HPLC) are: 1 ) pass the water and/or organic solvents through a 0.45

micron membrane filter and/or 2) sparge the water and/or organic solvent with an inert

gas such as nitrogen and/or 3) allow the water and/or organic solvent to be exposed to

molecular sieves until completely degassed.

It is also known in the art that microfilters are available commercially in the

micron range similar to that used to degas mobile phase for HPLC analysis. Such filters

may be obtained for example from A G Technology of Needham, Massachusetts.

Any of the above-mentioned methods of degassing may be employed in the

present invention. If, for example, a membrane filter (e.g. 0.45 micron) were employed

to degas the gelatin, the filter could be incorporated into the diafiltration system 16

shown in Figure 1. For example, the aqueous layer passing through the conduit 14 to

the diafiltration system 16 is first treated as described above to remove impurities via

the conduit 30. The recovered gelatin may then be filtered with a membrane filter to

remove air within the diafiltration system 16.

In another embodiment of the present invention, the degassing operation may

be established externally of the diafiltration system. Referring to Figure 2, the

recovered gelatin is sent via the conduit 26 to a conduit 27 which leads to a degassing

system 29 (e.g. a membrane filter). Once the gas (e.g. air) is removed from the gelatin,

the degassed gelatin is sent via the conduit 31 to be recycled or recovered. It is understood that the above described recycling system may be incorporated

into a conventional encapsulation apparatus to provide repeated or continual recycling

of waste encapsulation materials.

Although the present invention has been described with reference to the

particular embodiments herein set forth, it is understood that the present disclosure has

been made only by way of example and that numerous changes in details of

construction may be resorted to without departing from the spirit and scope of the

invention. Thus, the scope of the invention should not be limited by the foregoing

specifications.

Claims

What Is Claimed Is:

1. A method of treating a waste material containing gelatin comprising:

a) combining the waste material and a solvent for the gelatin to form a liquid

containing gelatin;

b) separating the liquid into a solvent based layer and a non-solvent based

layer; and

c) removing at least one of residual oils and particulates from the solvent

based layer to form a second liquid containing gelatin having a higher purity than the

first liquid.

2. The method of claim 1 comprising removing residual oils and non-soluble

components from the solvent based layer.

3. The method of claim 1 comprising:

1 ) dissolving the waste material and other soluble components of the waste

material in the solvent such that a dispersion comprising a waste material-containing

solution is dispersed within the remaining components of the encapsulation system is

formed;

2) permitting the dispersion to settle into an upper non-solvent phase and

a lower solvent based waste material-containing phase;

3) separating the lower phase from the upper phase; and 4) removing residual oils and particulates from the lower phase.

4. The method of claim 3 where the step of removing residual oils and

particulates from the lower phase comprises hot filtering the lower phase to thereby

form a filtrate.

5. The method of claim 4 further comprising concentrating the filtrate.

6. The method of claim 5 wherein the step of concentrating the filtrate

comprises concentrating the filtrate by a method selected from the group consisting of

diafiltration, short path distillation, and vacuum distillation.

7. The method of claim 3 comprising dissolving the waste material with up

to 5 volumes of the solvent.

8. The method of claim 3 comprising dissolving the waste material at a

temperature of from about 30 C to 70 C.

9. The method of claim 3 comprising hot filtering the lower phase at a

temperature sufficient to maintain the lower phase in a flowable condition.

10. The method of claim 1 wherein the separation step employs a sight glass,

an oil skimmer or hot filtration.

11. The method of claim 3 comprising hot filtering the lower phase at a

temperature of from about 30°C to 70°C.

12. The method of claim 3 comprising hot filtering the lower phase by diluting

the waste material at a dilution volume of up to 5 volumes of said solvent.

13. The method of claim 1 wherein the solvent is water.

14. The method of claim 3 wherein the hot filtering step is selected from the

group consisting of liquid:liquid centrifugation, submicro/microfiltration, liquid :Iiquid

coalescence, absorbence and the use of filter aids.

15. The method of claim 14 wherein the hot filtering step comprises subjecting

the lower phase to liquid:liquid centrifugation.

16. The method of claim 15 comprising applying a centrifugal force to the

lower phase in the range of from about 10 to 25,000 times the force of gravity.

17. The method of claim 16 wherein the centrifugal force is from about 5,000

to 25,000 times the force of gravity.

18. The method of claim 3 wherein the hot filtering step comprises subjecting

the lower phase to micro or sub-micro filtration using a micron or sub-micron pore size

filter.

19. The method of claim 18 wherein the pore size of the filter is from about

0.1 to 2.0 microns.

20. The method of claim 18 comprising treating the lower phase with

tangential flow filtration.

21. The method of claim 18 comprising treating the lower phase with depth

filtration.

22. The method of claim 3 wherein the hot filtering step comprises subjecting

the lower phase to liquid:liquid coalescence.

23. The method of claim 22 wherein liquid:liquid coalescence in conducted

in multiple stages.

24. The method of claim 2 further comprising sending the residual oils to the

non solvent phase.

25. The method of claim 4 further comprising removing the residual oils and

particulates to form a filtrate and recycling the filtrate.

26. The method of claim 25 further comprising removing at least some of the

solvent from the filtrate.

27. The method of claim 26 comprising treating the filtrate by a process

selected from the group consisting of vacuum distillation, short path distillation and

dialfiltration.

28. The method of claim 27 comprising treating the filtrate by short path

distillation at an evaporator temperature of from about 50 to 120 C.

29. The method of claim 28 comprising treating the filtrate by short path

distillation a pressure of from about 20 to 30 in. Hg.

30. The method of claim 26 further comprising concentrating the recyclable

gelatin to a final solids concentration of at least 20%.

31. The method of claim 3 further comprising distilling the upper phase to

separate oily components therefrom.

32. The method of claim 31 further comprising recovering the oily components

from the upper phase.

33. The method of claim 31 wherein the step of distilling the upper phase is

conducted by a process selected from a group consisting of vacuum distillation and

short path distillation.

34. The method of claim 1 wherein the waste material contains gelatin.

35. The method of claim 1 wherein the waste material contains a softening

agent, said method comprising separating the softening agent into the solvent based

layer.

36. The method of claim 35 wherein the softening agent is at least one polyol.

37. The method of claim 36 wherein the softening agent is glycerin.

38. The method of claim 26 wherein the filtrate contains a softening agent,

said process further comprising subjecting the filtrate to short path distillation or vacuum

distillation to form a liquid comprising gelatin and a softening agent.

39. The method of claim 27 further comprising diafiltering the filtrate to

produce a first concentrated stream of recoverable waste material and a second stream

containing impurities and separating the impurities from the second stream.

40. The method of claim 4 further comprising treating the hot filtered lower

phase to eliminate any affinity between the waste material and any dyes or pigments

that may be present.

41. The method of claim 39 wherein the filtrate contains a softening agent,

said method further comprising subjecting the filtrate to diafiltration to remove the

softening agent, and any dyes and solvent soluble impurities that may be present.

42. The method of claim 39 wherein the first concentrated stream is recycled.

43. The method of claim 39 further comprising recovering the separated

impurities.

44. The method of claim 39 comprising separating impurities from second

stream.

45. The method of claim 44 comprising treating the second stream by a

process selected from the group consisting of fractional distillation, short path

distillation, supercritical fluid extraction and reverse osmosis.

46. The method of claim 1 further comprising removing at least a substantial

portion of any gas contained within the solvent based layer.

47. The method of claim 1 further comprising recycling a portion of the

recovered waste material to step (a).

48. Apparatus for treating a waste material containing gelatin comprising:

a) combining means for combining the waste material and a solvent for the

gelatin to form a liquid containing gelatin,

b) separation means for separating the liquid into a solvent based layer and

a non-solvent based layer; and

c) removal means for removing residual oils and/or particulates from the

solvent based layer to form a second liquid containing gelatin having a higher purity

than the first liquid.

49. The apparatus of claim 48 comprising removal means for removing

residual oils and non-soluble components from the solvent based layer.

50. The apparatus of claim 48 comprising:

1) dissolution means for dissolving the waste material and other soluble

components of the waste material in the solvent such that a dispersion comprising a

waste material-containing solution is dispersed within the remaining components of the

encapsulation system is formed;

2) means for permitting the dispersion to settle into an upper non-solvent

phase and a lower solvent based waste material-containing phase;

3) separation means for separating the lower phase from the upper phase;

and

4) removal means for removing residual oils and particulates from the lower

phase.

51. The apparatus of claim 50 where the removal means for removing

residual oils and particulates from the lower phase comprises hot filtering means for hot

filtering the lower phase to thereby form a filtrate.

52. The apparatus of claim 51 further comprising concentration means for

concentrating the filtrate.

53. The apparatus of claim 52 wherein the concentration means is selected

from the group consisting of diafiltration means, short path distillation means and

vacuum distillation means.

54. The apparatus of claim 51 wherein the hot filtering means is selected from

the group consisting of liquid:liquid centrifugation device, a submicro/microfiltration

device, a liquid:liquid coalescence device, an absorbence device and a filter aid device.

55. The apparatus of claim 48 wherein the separation means is selected from

the group consisting of a sight glass, an oil skimmer, or a hot filtration device.

56. The apparatus of claim 54 wherein the hot filtering means comprises a

liquid:liquid centrifuge device.

57. The apparatus of claim 54 wherein the hot filtering means comprises a

micro or sub-micro filtration device comprising a micron or sub-micron pore size filter.

58. The apparatus of claim 57 wherein the filtration device comprises

tangential flow filters or depth filters.

59. The apparatus of claim 54 wherein the hot filtering means comprises a

liquid:liquid coalescence device.

60. The apparatus of claim 59 wherein the liquid:liquid coalescence device

comprises multiple stages.

61. The apparatus of claim 53 wherein the hot filtering means removes

residual oils and particulates to form a filtrate said apparatus further comprising filtrate

recycling means to recycle the filtrate.

62. The apparatus of claim 50 further comprising distillation means for

distilling the upper non-solvent phase to separate oily components therefrom.

63. The apparatus of claim 62 further comprising recovery means for

recovering any oily components from the upper phase.

64. The apparatus of claim 62 wherein the distillation means is selected from

a group consisting of, a fractional distillation device, a short path distillation device, and

a reverse osmosis device.

65. The apparatus of claim 50 further comprising recycling means for

recycling a portion of the recovered waste material to the dissolution means.

66. The apparatus of claim 51 further comprising means for treating the filtrate

to remove at least some of the solvent.

67. The apparatus of claim 66 wherein the treating means is selected from the

group consisting of a vacuum distillation device, a short path distillation device and a

dialfiltration device.

68. The apparatus of claim 67 wherein the treating means is a short path

distillation device.

69. The apparatus of claim 67 wherein the treating means is a dialfiltration

device which produces a first concentrated stream of recoverable waste and a second

stream containing impurities, said apparatus further comprising separation means for

separating the impurities from the second stream.

70 The apparatus of claim 68 further comprising recovery means for

recovering the separated impurities.

71. The apparatus of claim 69 further comprising distillation means for

distilling the second stream.

72. The apparatus of claim 51 further comprising means for forwarding the

residual oils to the upper phase.

73. The apparatus of claim 71 wherein the distillation means for distilling the

second stream is selected from the group consisting of a fractional distillation device, a short path distillation device, a supercritical fluid extraction device and a reverse

osmosis device.

74. The apparatus of claim 48 further comprising gas removing means for

removing at least a substantial portion of any gas contained within the solvent based

layer.