Crystallization of high-purity magnesium L-lactate

Abstract

A process is provided for the formation of high purity magnesium L-lactate crystals from homogeneous and heterogeneous decomposed organic wastes. The process provides magnesium L-lactate crystals with improved enantiomeric and overall purity that are particularly suitable for reuse in the production of new polylactic acid.

Description

[Technical field]

[0001] The present invention provides a process for the crystallization of high purity magnesium L-lactate from decomposed organic waste. Regarding s. [Background technology]

[0002] Lactic acid is the most widely occurring hydroxycarboxylic acid with applications in the food, chemical, pharmaceutical, and cosmetic industries. This naturally occurring organic acid can be produced by chemical synthesis or microbial fermentation. When produced by microbial fermentation, care must be taken to avoid the endogenous decrease in pH due to the fermentation of lactic acid in order to maintain the productivity of the microorganisms. A pH in the range of 5 to 7 is preferred and can be obtained by the addition of a base such as ammonium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, or calcium hydroxide, which neutralizes the lactic acid and thereby produces lactate salt. A reacidification step, for example using sulfuric acid, can be carried out to convert the lactate salt to lactic acid.

[0003] Approximately 60-80% of the production costs of lactic acid can be attributed to downstream processes, including purification, concentration, and separation of lactic acid / lactate from the fermentation broth. Additionally, it is desirable to reduce or eliminate the production of by-products (e.g., salts other than lactate).

[0004] Various methods have been previously proposed to recover and purify lactic acid and / or lactate from the fermentation broth. For example, a process for magnesium lactate purification based on crystallization is described in Wang Yong, et al., "Efficient magnesium lactate production with in situ product removal by crystallization", Bioresource technology 198(2015):658-663. Crystallization was carried out at 42 °C without the addition of crystal seeds. The fermentation medium used in the fermentor contained yeast extract, glucose, NaCl, sodium acetate, triammonium citrate, KH2PO4, MgSO4·7H2O, and MnSO4·7H2O. The product concentration, productivity, and fermentation yield with in situ product removal (ISPR) were 143 g L−1, respectively. -1 , 2.41g L -1 h -1 and reached 94.3%.

[0005] US Patent No. 9,689,007 describes a method for producing lactate or lactic acid from a "low sugar" plant extract via fermentation, comprising providing a fermentation medium containing at least 25 wt.% of a plant extract containing fermentable carbohydrates, and fermenting the fermentation medium with a lactic acid producing microorganism in the presence of a caustic magnesium salt to provide a fermentation broth containing up to 9.5 wt.% magnesium lactate at the end of the fermentation, the magnesium lactate being in soluble form during and at the end of the fermentation. To achieve a magnesium lactate concentration in the fermentation broth of up to 9.5 wt.% at the end of the fermentation, the fermentation medium containing the plant extract preferably contains fermentable carbohydrates at a concentration of up to 9.5 wt.%.

[0006] US 2014 / 0012041 describes a method for producing lactate, comprising subjecting an aqueous lactate solution containing formate to crystallization in an amount of 7.0% by weight or more relative to the lactate, and recovering the lactate, the aqueous lactate solution having a lactate concentration of 10.0-30.0% by weight.

[0007] US 2017 / 0218408 A1 describes a method for preparing a fermentation product comprising lactic acid, the method comprising: a) treating lignocellulosic material in a particulate form, having an average particle size of 0.1-250 mm, with a caustic magnesium salt in the presence of water to provide a treated aqueous lignocellulosic material; b) saccharifying the treated aqueous lignocellulosic material in the presence of a hydrolytic enzyme to provide a saccharified aqueous lignocellulosic material comprising fermentable sugars and a solid lignocellulosic fraction; c) simultaneously with step b), fermenting the saccharified aqueous lignocellulosic material in the presence of both a lactic acid forming microorganism and a caustic magnesium salt to provide an aqueous fermentation broth comprising magnesium lactate and a solid lignocellulosic fraction; d) recovering magnesium lactate from the broth, wherein the saccharification and fermentation are performed simultaneously. The feedstock for the process of US2017 / 0218408 is a lignocellulosic material, which includes materials containing cellulose, hemicellulose and lignin, and may be derived from, for example, plant biomass. Preferred lignocellulosic materials are selected from the group consisting of: wheat straw, sugarcane bagasse, corn stover, and mixtures thereof.

[0008] WO 2017 / 178426 states: - providing a fermentation medium comprising a fermentable carbon source to a fermentation reactor; - fermenting the fermentation medium with a lactic acid producing microorganism in the presence of an alkaline magnesium salt to provide a fermentation broth containing magnesium lactate; and - recovering solid magnesium lactate from the magnesium lactate-containing fermentation broth, wherein the concentration of solid magnesium lactate in the fermentation broth is maintained within the range of 5-40 vol.% calculated as solid magnesium lactate crystals relative to the total volume of the fermentation broth for at least 40% of the operating time of the fermentation process. A fermentation process for producing magnesium lactate from a carbon source is described, comprising: 12sugars) and / or polymers thereof.

[0009] WO 2017 / 207501 describes a method for separating biomass from a solid fermentation product, in which a slurry comprising biomass and a solid fermentation product is provided to the top of a biomass separator unit and an aqueous medium is provided to the bottom of the biomass separator unit, while a product stream comprising the solid fermentation product is withdrawn from the bottom of the biomass separator unit and a waste stream comprising the biomass is withdrawn from the top of the biomass separator unit. The solid fermentation product is a fermentation product that is present in the aqueous medium at a concentration above its saturation concentration and can be a crystalline or amorphous product.

[0010] The purification and crystallization methods described above are designed for fermentation broths derived from substantially homogeneous biomass-based feed streams with low content of soluble and insoluble impurities. However, there is a need to utilize more accessible and less expensive heterogeneous feedstocks for fermentation, such as mixed food waste from municipal, industrial and commercial sources. These heterogeneous feedstocks contain impurities such as salts, lipids, proteins, color components and inert materials. The fermentation broths derived from said heterogeneous feedstocks cannot be effectively processed by currently available methods to obtain high purity magnesium L-lactate product in a cost-effective manner.

[0011] WO 2020 / 110108 states: (a) providing a clarified fermentation broth, from which insoluble impurities have been removed, comprising magnesium lactate in soluble form resulting from a fermentation process, wherein the fermentation broth is at a temperature of about 45° C. to about 75° C.; (b) concentrating the clarified broth from step (a) to a lactate concentration of about 150 g / L to about 220 g / L; (c) performing at least one cooling crystallization of the concentrated clarified broth from step (b) to obtain magnesium lactate crystals; and (d) recovering the resulting magnesium lactate crystals. A process for the separation and purification of magnesium lactate from a fermentation broth is described, comprising:

[0012] There remains an unmet need for a simple, cost-effective method with high recovery yield for the crystallization of high purity L-lactate magnesium salt from decomposed organic waste. Summary of the Invention

[0013] The present invention provides a process for preparing high purity magnesium L-lactate from fermentation broth or other organic waste decomposition products containing lactic acid and / or lactate salts. The process of the present invention includes evaporative crystallization that utilizes fermentation broth or other organic waste decomposition products from a variety of sources, thereby making the process economically and environmentally beneficial. The process disclosed herein is suitable for fed-batch and continuous production in lactic acid recycling facilities.

[0014] The present invention is based in part on the unexpected discovery that high purity magnesium L-lactate crystals can be obtained from dispersions of decomposed organic waste, such as lactic acid fermentation broth, without the need for removal of D-lactic acid during and / or after fermentation. The process involves the use of evaporative crystallization under specific conditions that yields high purity magnesium L-lactate crystals already after one pass, despite the presence of significant amounts of impurities in the decomposed waste. Surprisingly, the process of the present invention resulted in improved enantiomer separation even when using decomposed organic waste containing 10 wt.% or less of endogenous D-lactic acid. Thus, the process of the present invention provides simple and economical high purity magnesium L-lactate crystals, even when heterogeneous feedstocks containing high concentrations of soluble and insoluble impurities from municipal, industrial and commercial sources are used.

[0015] According to a first aspect, the present invention provides a process for the formation of high purity magnesium L-lactate crystals from decomposing organic waste, the process comprising: a. providing a clarified dispersion of decomposed organic waste containing lactate at a concentration of about 50 to about 110 g / L; b. optionally concentrating the clarified dispersion of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified dispersion of step (a) or the concentrated clarified dispersion of step (b) to obtain a suspension containing seed magnesium L-lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium L-lactate crystals; and e. Recovering the magnesium L-lactate crystals obtained in step (d). Including, Steps (b) through (d) are carried out at an elevated temperature in the range of about 50° C. to about 90° C., inclusive, and with the application of a vacuum to a pressure of about 80 to about 300 mbar.

[0016] According to one embodiment, the decomposed organic waste is obtained from a lactic acid fermentation process. According to another embodiment, the decomposed organic waste is obtained from a lactic acid-containing waste. According to yet another embodiment, the decomposed organic waste is obtained from the hydrolysis of polylactic acid polymers.

[0017] According to a second aspect, the present invention provides a process for the formation of high purity magnesium L-lactate crystals from a fermentation broth, the process comprising: a. providing a clarified fermentation broth comprising lactate at a concentration of about 50 to about 110 g / L; b. optionally, concentrating the clarified broth of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified fermentation broth of step (a) or the concentrated fermentation broth of step (b) to obtain a suspension containing seed magnesium L-lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium L-lactate crystals; and e. Recovering the magnesium L-lactate crystals obtained in step (d). Including, Steps (b) through (d) are carried out at an elevated temperature in the range of about 50° C. to about 90° C., inclusive, and with the application of a vacuum to a pressure of about 80 to about 300 mbar.

[0018] According to a third aspect, the present invention provides a process for the formation of high purity magnesium L-lactate crystals from decomposing organic waste, the process comprising: a. providing a clarified dispersion of decomposed organic waste containing lactate at a concentration of about 50 to about 110 g / L; b. optionally concentrating the clarified dispersion of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified dispersion of step (a) or the concentrated clarified dispersion of step (b) to obtain a suspension containing seed magnesium L-lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium L-lactate crystals; and e. Recovering the magnesium L-lactate crystals obtained in step (d). Including, Steps (b) to (d) are carried out at a temperature of about 100° C. without a vacuum.

[0019] According to some embodiments, the clarified dispersion or clarified broth comprises decomposed organic waste or fermentation broth from which impurities have been removed using at least one of filtration, centrifugation, flotation, sedimentation, coagulation, flocculation, and decantation. Each possibility represents a separate embodiment. According to additional embodiments, the clarified dispersion or clarified broth comprises decomposed organic waste or fermentation broth from which impurities have been removed using filtration and / or centrifugation.

[0020] According to other embodiments, the organic waste comprises a carbohydrate source. According to further embodiments, the organic waste is selected from food waste, municipal food waste, household food waste, agricultural waste, industrial food waste from food processing facilities, commercial food waste (from hospitals, restaurants, shopping centers, airports, etc.), and mixtures or combinations thereof. Each possibility represents a separate embodiment.

[0021] According to certain embodiments, the decomposed organic waste contains endogenous D-lactic acid. According to specific embodiments, the decomposed organic waste contains 10 wt.% or less endogenous D-lactic acid.

[0022] According to some embodiments, step (b) is carried out to a lactate concentration of about 100 to about 130 g / L, inclusive of each value within the specified range.

[0023] According to various embodiments, the mixing in step (c) is carried out at a speed of about 50 to about 300 revolutions per minute (RPM), inclusive of each value within the specified range.

[0024] According to certain embodiments, the mixing in step (c) is carried out for at least 1 hour. According to other embodiments, the mixing in step (c) is carried out for about 1 hour to about 6 hours, inclusive, with each value within the specified range.

[0025] According to further embodiments, steps (b) through (d) are carried out at an elevated temperature in the range of about 50° C. to about 80° C., inclusive. According to other embodiments, steps (b) through (d) are carried out with an applied vacuum to a pressure of about 150 to about 250 mbar, inclusive. According to further embodiments, steps (b) through (d) are carried out with an applied vacuum to a pressure of about 250 to about 350 mbar, inclusive.

[0026] According to certain embodiments, the removal of about 70% to about 90% of the water from the suspension in step (d) is carried out at an evaporation rate of about 2 to about 5 wt % per hour, inclusive of each value within the specified range.

[0027] According to various embodiments, step (e) comprises filtration and / or centrifugation. According to specific embodiments, step (e) is carried out at room temperature.

[0028] According to certain embodiments, the process further comprises a step (f) of washing the obtained magnesium L-lactate crystals. According to certain embodiments, washing of the obtained magnesium L-lactate crystals is carried out in a solvent selected from water, ethanol, propanol, isobutanol, cyclohexane, acetone, ethyl acetate, and mixtures or combinations thereof. Each possibility represents a separate embodiment.

[0029] According to other embodiments, the process further comprises step (g) of drying the magnesium L-lactate crystals to a loss on drying (LOD) % of about 10% to about 20%, inclusive. According to certain embodiments, step (g) is carried out at an elevated temperature of about 50° C. to about 120° C., inclusive.

[0030] According to additional embodiments, the resulting magnesium L-lactate crystals are solubilized and recrystallized by repeating steps (c)-(e) multiple times. According to these embodiments, steps (c)-(e) are carried out for between 2 and 6 cycles, inclusive, with each value falling within the specified range.

[0031] According to a further embodiment, the recovery of magnesium L-lactate crystals is at least 90%.

[0032] According to other embodiments, the resulting magnesium L-lactate crystals are characterized by a median size smaller than 75 μm. According to certain embodiments, the resulting magnesium L-lactate crystals are characterized by a particle size distribution that includes a median size in the range of about 20 to about 100 μm, including values ​​within the specified range. According to yet other embodiments, the resulting magnesium L-lactate crystals are characterized by a median size greater than 75 μm. According to additional embodiments, the resulting magnesium L-lactate crystals are characterized by a particle size distribution that includes a median size in the range of about 100 to about 300 μm, including values ​​within the specified range.

[0033] According to some embodiments, the resulting magnesium L-lactate crystals contain less than 3% magnesium D-lactate. According to certain embodiments, the resulting magnesium L-lactate crystals contain less than 2% magnesium D-lactate. According to other embodiments, the resulting magnesium L-lactate crystals contain less than 1.5% magnesium D-lactate. According to yet other embodiments, the resulting magnesium L-lactate crystals contain less than 1% magnesium D-lactate.

[0034] According to additional embodiments, the present invention further provides high purity magnesium L-lactate crystals obtainable by the processes disclosed herein.

[0035] According to a further embodiment, the present invention provides a process for enriching L-lactate enantiomers from an enantiomeric mixture derived from decomposed organic waste, the process comprising: providing a clarified dispersion of decomposed organic waste comprising lactate salts, the lactate salts comprising an enantiomeric mixture of D- and L-lactate salts, at a concentration of about 50 to about 110 g / L; b. optionally concentrating the clarified dispersion of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified dispersion of step (a) or the concentrated clarified dispersion of step (b) to obtain a suspension containing seed magnesium lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium L-lactate crystals having enriched enantiomeric purity; and e. Recovering the magnesium L-lactate crystals obtained in step (d). Including, Steps (b) through (d) are carried out at an elevated temperature in the range of about 50° C. to about 90° C., inclusive, and with the application of a vacuum to a pressure of about 80 to about 300 mbar.

[0036] In one embodiment, the process provides an enrichment of the L-lactate enantiomer of up to 1% or more. In another embodiment, the process provides an enrichment of the L-lactate enantiomer of up to 5% or more. In yet another embodiment, the process provides an enrichment of the L-lactate enantiomer of up to 10% or more. In certain embodiments, the process provides an enrichment of the L-lactate enantiomer of 15% or less. In other embodiments, the process provides an enrichment of the L-lactate enantiomer of 20% or less. In yet other embodiments, the process provides an enrichment of the L-lactate enantiomer of 25% or less.

[0037] It should be understood that any combination of each aspect and embodiment disclosed herein is expressly encompassed by the present disclosure.

[0038] Further embodiments and full scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. [Brief description of the drawings]

[0039] [Figure 1]FIG. 1 shows the particle size distribution of magnesium L-lactate crystals obtained according to some embodiments of the present invention. [Diagram 2] Figures 2A-2F show optical microscope images of magnesium L-lactate crystals obtained according to some embodiments of the present invention that were retained on sieves having cut-off sizes of 710 μm (2A), 500 μm (2B), 300 μm (2C), 100 μm (2D), and 75 μm (2E), and Figure 2F shows an optical microscope image of magnesium L-lactate crystals that passed through the 75 μm sieve. [Diagram 3] FIG. 3 shows the particle size distribution of magnesium L-lactate crystals obtained using cooling crystallization. [Figure 4] Figures 4A-4F show optical microscope images of magnesium L-lactate crystals obtained using cooling crystallization that were retained on sieves having cut-off sizes of 710 μm (4A), 500 μm (4B), 300 μm (4C), 100 μm (4D), and 75 μm (4E), and Figure 4F shows an optical microscope image of magnesium L-lactate crystals that passed through the 75 μm sieve. [Diagram 5] FIG. 5 shows the particle size distribution of magnesium L-lactate crystals obtained according to some embodiments of the present invention following recrystallization. [Figure 6] FIG. 6 shows the particle size distribution of magnesium L-lactate crystals obtained using different evaporation rates. [Figure 7] FIG. 7 shows the particle size distribution of magnesium L-lactate crystals obtained according to some embodiments of the present invention from fed-batch constant volume crystallization. [Figure 8] FIG. 8 shows optical microscope images of magnesium L-lactate crystals obtained according to some embodiments of the present invention from fed-batch constant volume crystallization. [Figure 9] FIG. 9 shows the particle size distribution of magnesium L-lactate crystals obtained according to some embodiments of the present invention from fed-batch constant concentration crystallization. [Figure 10] FIG. 10 shows optical microscope images of magnesium L-lactate crystals obtained according to some embodiments of the present invention from fed-batch constant concentration crystallization. [Figure 11] FIG. 11 shows the particle size distribution of magnesium L-lactate crystals obtained according to some embodiments of the present invention following recrystallization and counterion replacement of magnesium lactate obtained from degraded PLA 4032D with sodium hydroxide. [Figure 12] FIG. 12 shows optical microscope images of magnesium L-lactate crystals obtained according to some embodiments of the present invention following recrystallization and counterion replacement of magnesium lactate obtained from degraded PLA 4032D with sodium hydroxide. [Figure 13] FIG. 13 shows the particle size distribution of magnesium L-lactate crystals obtained according to some embodiments of the present invention following recrystallization and counterion replacement of magnesium lactate obtained from degraded PLA with sodium hydroxide. [Figure 14] FIG. 14 shows optical microscope images of magnesium L-lactate crystals obtained according to some embodiments of the present invention following recrystallization and counterion replacement of magnesium lactate obtained from degraded PLA with sodium hydroxide. [Figure 15] FIG. 15 shows the particle size distribution of magnesium L-lactate crystals obtained from crystallization of magnesium L-lactate at 30° C. [Figure 16] FIG. 16 shows an optical microscope image of magnesium L-lactate crystals obtained from crystallization of magnesium L-lactate at 30° C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The present invention provides a process for the formation of magnesium L-lactate crystals from fermentation broths or other organic waste decomposition products that may be obtained from feedstocks containing high concentrations of soluble and insoluble impurities from municipal, industrial and commercial sources. The process disclosed herein for the first time provides L-lactate crystals that exhibit high overall purity, high enantiomeric purity, can be easily manipulated with desirable filterability and particle size distribution, and is particularly advantageous for use in subsequent polylactic acid formation.

[0041] According to certain aspects and embodiments, a clarified dispersion of decomposed organic waste or fermentation broth is obtained, the clarified dispersion or broth containing lactate ions at a concentration of about 50 to about 110 g / L, including each value within the specified range. Exemplary lactate concentrations include, but are not limited to, about 50 g / L, about 55 g / L, about 60 g / L, about 65 g / L, about 70 g / L, about 75 g / L, about 80 g / L, about 85 g / L, about 90 g / L, about 95 g / L, about 100 g / L, about 105 g / L, or about 110 g / L. Each possibility represents a separate embodiment.

[0042] According to certain embodiments, the dispersion is a decomposition product of any lactic acid-containing waste, such as, but not limited to, polylactic acid polymers subjected to hydrolysis. According to other embodiments, fermentation broth from organic waste feedstock is used. Organic waste feedstock within the scope of the present invention can be obtained from any waste source, including, but not limited to, food waste, municipal food waste, household food waste, agricultural waste, industrial food waste from food processing facilities, commercial food waste (from hospitals, restaurants, shopping centers, airports, etc.), and mixtures or combinations thereof. Each possibility represents a separate embodiment. Organic waste can also come from residues ranging from animal and human waste, vegetable and fruit residues, plants, cooked foods, protein residues, slaughter waste, and combinations thereof. Each possibility represents a separate embodiment. Industrial organic food waste can include factory waste such as by-products, factory rejects, market returns, or inedible food part waste (skin, fat, crusts, peels, etc.). Each possibility represents a separate embodiment. Commercial organic food waste can include waste from shopping malls, restaurants, supermarkets, etc. Each possibility represents a separate embodiment.

[0043] According to various aspects and embodiments, the dispersion of decomposed organic waste is a fermentation broth obtained from a fermentation process of a carbohydrate source. When a non-homogeneous feedstock is used, the dispersion of decomposed organic waste or fermentation broth typically contains insoluble organic-based impurities, such as, but not limited to, microorganisms (e.g., lactic acid-producing microorganisms, including, e.g., yeast, bacteria, and fungi), fats and oils, lipids, aggregated proteins, bone chips, hair, precipitated salts, cell debris, fibers (e.g., fruit and / or vegetable peels), and residual unprocessed waste (e.g., food shells, seeds, food insoluble particles and debris, etc.). Each possibility represents a separate embodiment. Non-limiting examples of insoluble inorganic-based impurities include plastic, glass, residues from food packaging containers, sand, and combinations thereof. Each possibility represents a separate embodiment.

[0044] Non-limiting examples of soluble impurities include water, solvents, polysaccharides, starch, cellulose, hemicellulose, lignin, seed debris, salts, color components (e.g., tannins, flavonoids, and carotenoids), and combinations thereof. Each possibility represents a separate embodiment. Typically, the soluble and insoluble impurity content of the dispersion or broth is the same as the soluble and insoluble impurity content of the organic waste feedstock. In some embodiments, the soluble and insoluble impurity content of the dispersion or broth is at least about 1 wt% lower compared to the soluble and insoluble impurity content of the organic waste feedstock. In further embodiments, the soluble and insoluble impurity content of the dispersion or broth is at least about 5 wt%, about 10 wt%, about 15 wt%, about 20 wt%, about 30 wt%, about 40 wt%, or about 50 wt% lower compared to the soluble and insoluble impurity content of the organic waste feedstock. Each possibility represents a separate embodiment.

[0045] According to the principles of the present invention, insoluble impurities are removed to obtain a clarified dispersion or fermentation broth of the decomposition waste. The impurities may be removed before and / or after the decomposition or fermentation of the waste to produce a clarified liquid. According to certain embodiments, separation of the insoluble impurities is performed before the decomposition or fermentation. For example, in some embodiments, the complex organic waste may be heat treated, followed by enzymatic treatment, followed by centrifugation, e.g., decanter type centrifugation, to remove most of the insoluble impurities. The supernatant (still with some impurities) is pumped into a vessel or fermenter for lactic acid production.

[0046] According to various embodiments, separation of most of the insoluble impurities is carried out after digestion or fermentation. Clarification can be achieved via at least one of filtration, centrifugation, flotation, sedimentation, coagulation, flocculation, and decantation. Each possibility represents a separate embodiment. Typically, the clarified dispersion or broth comprises a dispersion or fermentation broth of digested organic waste from which insoluble impurities have been removed using filtration (e.g., microfiltration) and / or centrifugation.

[0047] Although not necessary to obtain a clarified dispersion or broth according to the principles of the present invention, additional removal of impurities can be employed. This includes, for example, product separation or primary recovery, using, for example, ultrafiltration, solvent extraction, salt precipitation, and rebound extraction, to recover or separate extracted components that are substantially different from the desired lactic acid product, such as salts and proteins. Each possibility represents a separate embodiment. Further purification may be performed to remove contaminants with similar physical and chemical properties, using crystallization, distillation, evaporation, nanofiltration, reverse osmosis (RO) filtration, solvent extraction, electrodialysis, and various types of chromatography (such as adsorption or ion exchange). Each possibility represents a separate embodiment.

[0048] Purification methods known in the art are typically designed for a substantially homogeneous biomass-based feed stream-derived fermentation broth with a relatively low content of solid impurities, and some of the methods utilize crystallization and / or maintaining lactate in particulate form during the fermentation step. Furthermore, some of the known methods are designed to use a specific amount of carbohydrate in the feed stream at the beginning of the fermentation process and, as a result, a specific amount of magnesium lactate product at the end of the fermentation process. For example, U.S. Patent No. 9,689,007 specifies that the fermentation medium should contain at least 25 wt.% of a plant extract containing fermentable carbohydrates at the beginning of the process, and that the fermentation broth at the end of the fermentation should contain a maximum of 9.5 wt.% magnesium lactate.

[0049] The present invention allows the production of high purity magnesium L-lactate from homogeneous biomass-based feed streams, but also advantageously from more complex feedstocks, such as heterogeneous mixed food waste from municipal, industrial and commercial sources, which contain high contents of soluble and insoluble impurities. Furthermore, known methods are not suitable for fermentation broths from complex feedstocks that have a wide range of possible initial fermentable sugar concentrations, resulting in fermentation broths with a wide range of lactate concentrations. Surprisingly, the inventors have found a simple and economical process for obtaining high purity magnesium L-lactate crystals that can be derived from heterogeneous fermentation broths obtained from complex feedstocks containing a wide range of initial fermentable sugar concentrations. Therefore, the process is not limited or restricted by the origin of the initial organic feedstock or by the amount of fermentable sugars in the initial organic feedstock.

[0050] The present invention advantageously allows the production of high purity magnesium L-lactate crystals from heterogeneous feedstocks with high yield and enantiomer separation. Surprisingly, it is now disclosed for the first time that high purity magnesium L-lactate crystals can be obtained from decomposed organic waste containing endogenous D-lactic acid. Typically, the organic waste contains endogenous D-lactic acid, L-lactic acid or both L- and D-lactic acid, e.g., from natural fermentation processes, e.g., in dairy products. The present invention advantageously allows the production of high purity magnesium L-lactate crystals from decomposed organic waste containing 10 wt.% or less endogenous D-lactic acid.

[0051] In accordance with the principles of the present invention, after obtaining a clarified dispersion of decomposed organic waste or fermentation broth from which insoluble impurities have been removed, the concentration of lactate ions is increased to a range of about 100 to about 150 g / L, inclusive of each value within the range specified, as the case may be. Preferably, lactate ions are concentrated to a concentration of about 100 to about 130 g / L, inclusive of each value within the range specified. Representative concentrations of lactate salt after concentration include, but are not limited to, about 100 g / L, about 105 g / L, about 110 g / L, about 115 g / L, about 120 g / L, about 125 g / L, about 130 g / L, about 135 g / L, about 140 g / L, about 145 g / L, or about 150 g / L. Each possibility represents a separate embodiment. Advantageously, the present invention discloses that much lower lactate concentrations of about 100 to about 150 g / L can be utilized as the initial concentration prior to crystallization, thereby reducing costs and increasing effectiveness. The lactate concentration process is carried out at elevated temperatures of about 50° C. to about 90° C., inclusive, and at pressures of about 80 to about 300 mbar.

[0052] Formation of seed magnesium L-lactate crystals is then carried out by mixing the clarified or concentrated dispersion or broth at an elevated temperature of about 50° C. to about 90° C., inclusive, with a vacuum applied to a pressure of about 80 to about 300 mbar. Typically, the dispersion or broth is mixed using a mixer or homogenizer at a speed ranging from about 50 to about 300 revolutions per minute (RPM), inclusive, with a speed ranging from about 50 to about 300 revolutions per minute (RPM). Exemplary mixing speeds include, but are not limited to, about 50 RPM, about 75 RPM, about 100 RPM, about 125 RPM, about 150 RPM, about 175 RPM, about 200 RPM, about 225 RPM, about 250 RPM, about 275 RPM, or about 300 RPM. Each possibility represents a separate embodiment. According to certain embodiments, the mixing is carried out for at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 6 hours, or more. Each possibility represents a separate embodiment. It is contemplated that the processes disclosed herein may further include the addition of exogenous magnesium L-lactate seeds to facilitate the crystallization process.

[0053] Following the formation of seed magnesium L-lactate crystals, removal of about 70% to about 90% of the water from the suspension is carried out at elevated temperatures of about 50° C. to about 90° C., inclusive, and applying a vacuum to a pressure of about 80 to about 300 mbar. Typically, at least about 70%, about 75%, about 80%, about 85%, or about 90% of the water is removed at this stage.

[0054] Throughout these steps, the temperature is about 50° C., about 55° C., about 60° C., about 65° C., about 70° C., about 75° C., about 80° C., about 85° C., or about 90° C. Each possibility represents a separate embodiment. The application of a vacuum may be at about 80 mbar, about 85 mbar, about 90 mbar, about 95 mbar, about 100 mbar, about 105 mbar, about 110 mbar, about 115 mbar, about 120 mbar, about 125 mbar, about 130 mbar, about 135 mbar, about 140 mbar, about 145 mbar, about 150 mbar, about 155 mbar, about 160 mbar, about 165 mbar, about 170 mbar, about 175 mbar, about 180 mbar, about 185 mbar, about 190 mbar, about 195 mbar, about 200 mbar, about 205 mbar, about 210 mbar, about 215 mbar, about 220 mbar, about 225 mbar, about 230 mbar, about 235 mbar, about 240 mbar, about 245 mbar, about 250 mbar, about 255 mbar, about 260 mbar, about 265 mbar, about 270 mbar, about 275 mbar, about 280 mbar, about 285 mbar, about 290 mbar, about 295 mbar, about 300 mbar, about 305 mbar, about 310 mbar, about 315 mbar, about 320 mbar, about 325 mbar, about 330 mbar, about 340 mbar, about 345 mbar, about 350 mbar, about 355 mbar, about 360 mbar, about 365 mbar, about 370 mbar, about 375 mbar, about 380 mbar, about 385 mbar, about 390 mbar, about 400 mbar, about 4 The process can be carried out as known in the art, for example using a rotary evaporator, to a pressure of about 30 mbar, about 235 mbar, about 240 mbar, about 245 mbar, about 250 mbar, about 255 mbar, about 260 mbar, about 265 mbar, about 270 mbar, about 275 mbar, about 280 mbar, about 285 mbar, about 290 mbar, about 295 mbar, about 300 mbar, about 305 mbar, about 310 mbar, about 315 mbar, about 320 mbar, about 325 mbar, about 330 mbar, about 335 mbar, about 340 mbar, about 345 mbar, or about 350 mbar. Each possibility represents a separate embodiment. Alternatively, throughout these steps, the temperature is about 100° C. and no vacuum is applied.

[0055] According to certain aspects and embodiments, the rate of evaporation is within the range of about 2 to about 5% weight loss per hour, including each value within the range specified. Without being bound by any theory or mechanism of action, at this evaporation rate, the resulting magnesium L-lactate crystals exhibit the best filterability, overall purity, and enantiomeric purity.

[0056] The resulting magnesium L-lactate crystals are then recovered and separated from the remaining mother liquor. As used herein, the term "magnesium L-lactate" refers to the magnesium salt of a hydroxycarboxylic acid (CHCH(OH)COH) having the formula Mg(LA). The term "magnesium L-lactate" refers to any solvate and / or polymorph of Mg(LA), including but not limited to Mg(LA) dihydrate. The term "mother liquor" as used herein refers to the liquid remaining after crystallization of magnesium L-lactate crystals. In some embodiments, the resulting magnesium L-lactate crystals are separated from the remaining liquid by a method selected from microfiltration, nanofiltration, centrifugation, or another method known in the art. Each possibility represents a separate embodiment. In some embodiments, the process of the present invention further comprises a washing and / or purification step, including washing and / or purifying the resulting magnesium L-lactate crystals. The washing can be carried out using an organic solvent or an aqueous solution. Each possibility represents a separate embodiment. In some embodiments, the organic solvent comprises one or more of ethanol, propanol, isobutanol, cyclohexane, acetone, ethyl acetate, and combinations thereof. Each possibility represents a separate embodiment. The aqueous solution comprises water. It has now been disclosed for the first time that washing magnesium L-lactate crystals with water further improves the enantiomeric purity. Without being bound by any theory or mechanism of action, it is believed that D-lactate crystals adhere to the surface of magnesium L-lactate crystals, which are then washed with water, resulting in good enantiomeric purity. Thus, the present invention further provides a method for increasing the enantiomeric purity of magnesium L-lactate crystals, which comprises washing magnesium L-lactate crystals obtained from the crystallization of magnesium L-lactate at high temperature and reduced pressure with an aqueous solution. In some embodiments, the method comprises reducing the proportion of magnesium D-lactate in the magnesium L-lactate crystals to at least 50% (w / w). Preferably, washing is carried out at room temperature, for example, at about 10°C, about 15°C, about 20°C, about 25°C, or about 30°C.Each possibility represents a separate embodiment.

[0057] In some embodiments, the washing and / or purification step further comprises at least one of a polishing step, extraction, microfiltration, nanofiltration, activated carbon treatment, distillation, and grinding. Each possibility represents a separate embodiment. In further embodiments, the process of the present invention further comprises a drying step to achieve the desired % loss on drying. Representative LOD values ​​include, but are not limited to, about 10% to about 20%, including each value within the specified range.

[0058] In accordance with the principles of the present invention, the process disclosed herein may further comprise solubilizing the recovered magnesium L-lactate crystals in a suitable solvent and recrystallizing them at an elevated temperature of about 50°C to about 90°C, including each value within the specified range, and applying a vacuum to a pressure of about 80 to about 300 mbar, as detailed above. This solubilization and recrystallization may be carried out for additional cycles as necessary to obtain the required purity of the crystals, for example at least one additional cycle, at least two, at least three, at least four, at least five, at least six, or at least ten additional cycles. Each possibility represents a separate embodiment, however, it should be understood that due to the improved purity of the resulting magnesium L-lactate crystals, one cycle may be sufficient as disclosed herein.

[0059] The recovery of magnesium L-lactate crystals obtained is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95% or more. Each possibility represents a separate embodiment. The magnesium L-lactate crystals obtained by the processes as disclosed herein can be further acidified to lactic acid for subsequent reuse.

[0060] In some embodiments, the resulting magnesium L-lactate crystals exhibit a high purity of at least about 85 wt%, about 90%, about 92%, about 94 wt%, about 95 wt%, about 96 wt%, about 97 wt%, about 98 wt%, or about 99 wt%. Each possibility represents a separate embodiment. According to these embodiments, the magnesium L-lactate crystals contain less than about 15 wt%, e.g., about 10 wt%, about 9 wt%, about 8 wt%, about 7 wt%, about 6 wt%, about 5 wt%, about 4 wt%, about 3 wt%, about 2 wt%, about 1 wt% or less impurities. Each possibility represents a separate embodiment.

[0061] In further embodiments, the resulting magnesium L-lactate crystals contain less than 3% magnesium D-lactate, for example about 2.9%, about 2.8%, about 2.7%, about 2.6%, about 2.5%, about 2.4%, about 2.3%, about 2.2%, about 2.1%, about 2.0%, about 1.9%, about 1.8%, about 1.7%, about 1.6%, about 1.5%, about 1.4%, about 1.3%, about 1.2%, about 1.1%, about 1% or less. Each possibility represents a separate embodiment. Thus, the process of the present invention also provides for enantiomer enrichment to enrich L-lactate enantiomers from the enantiomeric mixture of D- and L-lactate monomers. This enrichment is particularly useful for recycling lactic acid. The enrichment of L-lactate enantiomer by the process of the present invention is at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or even more of the initial L-lactate content. Each possibility represents a separate embodiment. For example, for an initial enantiomer mixture containing 90% L-lactate and 10% D-lactate, an enrichment of 10% would result in a magnesium lactate salt containing 99% L-lactate and 1% D-lactate. Within the scope of the present invention is a reduction in D-lactate content by the process disclosed herein of at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or even 100% of the initial D-lactate content. Each possibility represents a separate embodiment. For example, for an initial enantiomeric mixture containing 90% L-lactate and 10% D-lactate, a 50% reduction in the D-lactate content would result in a magnesium lactate salt containing 95% L-lactate and 5% D-lactate.

[0062] In various embodiments, the resulting magnesium L-lactate crystals are characterized by a median particle size of less than 75 μm. In other embodiments, the resulting magnesium L-lactate crystals are characterized by a median particle size of greater than 75 μm. The term "particle size" as used herein refers to the length of the particle (i.e., crystal) in its shortest dimension. The particles have a shape selected from spherical, non-spherical, oblong, flaky, platelet-like, spongy, and combinations thereof. Each possibility represents a separate embodiment. Preferably, the resulting magnesium L-lactate crystals are characterized by a particle size distribution that may be unimodal, bimodal, or trimodal with a median particle size in the range of about 20-100 μm, or about 100-300 μm, including each value within the specified range. The terms "median" or "d" as used herein interchangeably refer to the particle size distribution of the particles. 50 " refers to the particle size at which the cumulative volume-based distribution percentage reaches 50%. In other words, the median particle size represents the value below which half of the particles have a diameter and above which half of the particles have a diameter. Thus, the resulting magnesium L-lactate crystals typically have a median particle size of about 25 μm, about 50 μm, about 75 μm, about 100 μm, about 125 μm, about 150 μm, about 175 μm, about 200 μm, about 225 μm, about 250 μm, about 275 μm, or about 300 μm. Each possibility represents a separate embodiment.

[0063] Although the processes disclosed herein are primarily designed to produce high purity magnesium L-lactate crystals, the same processes may be used to produce high purity magnesium D-lactate crystals as well.

[0064] Thus, according to certain aspects and embodiments, the present invention provides a process for the formation of high purity magnesium D-lactate crystals from decomposing organic waste, the process comprising: a. providing a clarified dispersion of decomposed organic waste containing lactate at a concentration of about 50 to about 110 g / L; b. optionally concentrating the clarified dispersion of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified dispersion of step (a) or the concentrated clarified dispersion of step (b) to obtain a suspension containing seed magnesium D-lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium D-lactate crystals; and e. Recovering the magnesium D-lactate crystals obtained in step (d). Including, Steps (b) through (d) are carried out at an elevated temperature in the range of about 50° C. to about 90° C., inclusive, and with the application of a vacuum to a pressure of about 80 to about 300 mbar.

[0065] According to other aspects and embodiments, the present invention provides a process for enriching D-lactate enantiomers from an enantiomeric mixture derived from decomposing organic waste, the process comprising: providing a clarified dispersion of decomposed organic waste comprising a lactate salt comprising an enantiomeric mixture of D- and L-lactic acid at a concentration of about 50 to about 110 g / L; b. optionally concentrating the clarified dispersion of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified dispersion of step (a) or the concentrated clarified dispersion of step (b) to obtain a suspension containing seed magnesium lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium D-lactate crystals having enriched enantiomeric purity; and e. Recovering the magnesium D-lactate crystals obtained in step (d). Including, Steps (b) through (d) are carried out at an elevated temperature in the range of about 50° C. to about 90° C., inclusive, and with the application of a vacuum to a pressure of about 80 to about 300 mbar.

[0066] The term "about" as used herein refers to ±10% of the specified value.

[0067] Throughout the specification and claims, the words "comprise" and "contain" and variations of these words, such as "comprising" and "including," mean "including but not limited to" and are not intended to (and do not) exclude other moieties, additives, components, integers or steps.

[0068] As used herein, the singular forms "a," "an," and "the" include the plural unless the context clearly dictates otherwise. Thus, for example, reference to a "solvent" includes combinations of solvents as known in the art.

[0069] As used herein, the term "and" or "or" includes "and / or" unless the context clearly dictates otherwise.

[0070] The following examples are presented to more fully illustrate some embodiments of the present invention, but should not be construed as limiting the broad scope of the present invention in any way. Those skilled in the art can easily devise many variations and modifications of the principles disclosed herein without departing from the scope of the present invention.

[0071] Working Example Example 1. Fermentation of the mixed food waste feedstock was carried out using magnesium hydroxide as an alkalizing agent added to maintain the pH within the range of 5-7. The lactate-containing fermentation broth was centrifuged and filtered to produce a clear supernatant with a lactate concentration of 75 g / L. The supernatant was maintained at 60 °C and 180 mbar vacuum until a lactate concentration of 120 g / L. The concentrated supernatant was stirred at 200 RPM for 4 hours under the same conditions to allow seed crystal formation and then concentrated again to remove 80% of the water. The concentrate was cooled to 25 °C and filtered using a Büchner funnel loaded with Whatman 3 filter paper. The resulting crystals were washed with acetone and dried at 80 °C. The product yield was 70% w / w with an assay of 97.4%. The D / L-lactate ratio in the supernatant was initially 3.7% / 96.3%, while the D / L-lactate ratio in the mother liquor was 8.6% / 91.4%, resulting in a D / L-lactate ratio of 1.2% / 98.8% in the magnesium lactate crystals. Surprisingly, washing the magnesium lactate crystals with water further improved the enantiomeric purity. Without being bound by any theory or mechanism of action, it is believed that the D-lactate crystals adhere to the surface of the L-lactate crystals and are thereby washed with water, resulting in better enantiomeric purity.

[0072] Example 2. Magnesium L-lactate crystals produced as described in Example 1 were evaluated for their particle size distribution using a series of sieves with the following size cutoffs: 75 μm, 100 μm, 300 μm, and 710 μm. The resulting particle size distribution profiles are presented in FIG. 1 and Table 1.

[0073] [Table 1]

[0074] The crystals were observed under an optical microscope, and Figures 2A-2F show that the crystals presented a relatively uniform shape with characteristic crystal faces.

[0075] Example 3. Crystals produced as described in Example 1 and characterized as described in Example 2 were compared to crystals obtained by a process in which a clarified fermentation broth with a lactate concentration of 98 g / L was concentrated at 60° C. to a lactate concentration of 215 g / L. The concentrate was cooled to 20° C. at a rate of 2° C. / min, and the crystals were filtered and washed with cold water (5° C.). The particle size distribution of the crystals obtained by the process described in this example is presented in FIG. 3 and Table 2, and optical microscope images of the crystals are shown in FIGS. 4A-4F.

[0076] [Table 2]

[0077] Example 4. Fermentation of the mixed food waste feedstock was carried out using magnesium hydroxide as an alkalizing agent added to maintain the pH within the range of 5-7. The lactate-containing fermentation broth was centrifuged and filtered to produce a clear supernatant with a lactate concentration of 78 g / L. The supernatant was maintained at 60 °C and 200 mbar vacuum until a lactate concentration of 122 g / L. The concentrated supernatant was stirred at 200 RPM for 4 hours under the same conditions to allow seed crystal formation and then concentrated again to remove 80% of the water. The concentrate was cooled to 25 °C and filtered using a Büchner funnel loaded with Whatman 3 filter paper. The resulting crystals were washed with acetone and water and dried at 80 °C. The product yield was 74% w / w with an assay of 96.0%. The D / L-lactate ratio of the supernatant was initially 3.1% / 96.9%, while the D / L-lactate ratio of the mother liquor was 8.3% / 91.7% and the resulting D / L-lactate ratio in the magnesium lactate crystals was 1.6% / 98.4%. The resulting magnesium lactate crystals were redissolved to a final concentration of 110 g / L and the solution was treated with activated charcoal to remove colored impurities and filtered. The clear solution was stirred at 200 RPM for 6 hours at 60°C to allow seed crystal formation and then concentrated again to remove 80% of the water. The concentrate was cooled to 30°C and filtered using a Buchner funnel loaded with Whatman 3 filter paper. The resulting crystals were washed with acetone and water and dried at 70°C. The product yield was 66% w / w with an assay of 98.4%. The D / L-lactate ratio of the recrystallization solution was initially 1.6% / 98.4%, whereas the D / L-lactate ratio of the mother liquor was 5.3% / 94.7%, resulting in a D / L-lactate ratio of 0.8% / 99.2% in the magnesium lactate crystals.

[0078] Example 5. Magnesium L-lactate crystals produced as described in Example 4 were evaluated for their particle size distribution as described in Example 2. The resulting particle size distribution profile is presented in Figure 5 and Table 3.

[0079] [Table 3]

[0080] As is evident from these results, the crystals obtained by the process of the present invention as described in Examples 1 and 4 were much larger than those obtained by the cooling crystallization process as described in Example 3. Specifically, most of the crystals obtained by the process of the present invention were larger than 100 microns, while those obtained by the cooling crystallization process were smaller than 75 microns. Also, the crystals obtained by the cooling crystallization process showed few characteristic crystal faces and were mostly in the form of aggregates.

[0081] Example 6. To investigate the effect of evaporation rate on the attributes of the resulting magnesium lactate crystals, three crystallization experiments, named "slow", "medium" and "fast", were carried out at different crystallization conditions as detailed in Table 4. The experiments were carried out on clarified broth from lactic acid fermentation experiments as described in Examples 1 and 4.

[0082] [Table 4]

[0083] Four different parameters were evaluated: a) cake moisture - measured after the initial filtration and before the aqueous washes. Cake moisture indicates filterability, with lower values ​​indicating more mother liquor was removed in the filtration; b) crystal purity - measured using HPLC; c) yield - (corrected according to crystal purity); and d) D-lactate - measured using HPLC. The results are presented in Table 5.

[0084] [Table 5]

[0085] The medium evaporation rate showed the best results in terms of filterability, with 4-5% less water than the slow or fast evaporation rates. This rate also resulted in crystals of the highest purity and lowest % D-lactate. A downward trend was detected in the total crystallization yield at fast evaporation rates.

[0086] The crystals obtained from the experiment were also characterized by inductively coupled plasma (ICP) elemental analysis, and the results are presented in Table 6.

[0087] [Table 6]

[0088] These results suggested that the medium evaporation rate crystallization was superior in terms of removing elemental impurities during crystallization. In particular, calcium as well as chloride, potassium, sodium and phosphorus concentrations were significantly reduced by the medium rate crystallization compared to crystallization at low or high evaporation rates. The particle size distribution of the resulting crystals was also evaluated using sieves with different cutoffs. The results suggested that the medium rate crystallization formed the largest crystals with >75% of the crystals being larger than 100 μm. The results are shown in Figure 6. However, it is noted that the particle size distribution based on sieving is less accurate due to the tendency of the crystals to form clusters.

[0089] Taken together, these results indicate that intermediate rate crystallization produces the highest quality magnesium lactate crystals.

[0090] Example 7. The lactic acid fermentation broth was centrifuged and filtered to produce 1 kg of clear supernatant with 7% lactate. The supernatant was concentrated to 12% lactate using a rotary evaporator, removing 42 wt%. The resulting concentrate was transferred to a 0.5 L reactor preheated to 70°C and stirred at 300 RPM. The supernatant was reduced in vacuum (315 mbar, 280 mbar or 250 mbar) at a rate of 7.65 g / h or 135 g / h, respectively. After removal of 80 wt%, the crystals were collected and filtered using a sintered glass funnel. The resulting crystals were washed with cold water and dried at 70°C. As exemplified in Example 6, intermediate crystallization rates, with evaporation occurring between 8 and 16 hours with evaporation rates of 2.4 to 4.8 wt% per hour, gave the best results.

[0091] Example 8. A fed-batch crystallization at constant weight was carried out. The lactic acid fermentation broth was centrifuged and filtered to produce 2 kg of clear supernatant with 7% lactic acid. 20% of the supernatant (0.4 kg) was added to a 0.5 L reactor preheated to 85° C. and stirred at 300 RPM. The remaining 80% (1.6 kg) was added to a separate vessel heated to 60° C. and connected to the reactor with a peristaltic pump. The supernatant was reduced in vacuum (280 mbar) at a rate of 80 g / h. During evaporation, the supernatant was added at the same rate. The internal temperature during crystallization was maintained at 70° C. After 20 hours, when all the supernatant had been added, the crystals were collected and filtered using a sintered glass funnel. The obtained crystals were washed with cold water and dried at 70° C. Yield: 57%, Assay: 98.6%, D-lactate: 3.8%, Original %D-lactate: 7.0%. The crystals were characterized for their size distribution through sieving. The results are shown in Figure 7. The crystals were observed under an optical microscope. Figure 8 shows an image of the crystals remaining on top of the 50 μm sieve.

[0092] Example 9. A fed-batch crystallization at constant concentration was carried out. The lactic acid fermentation broth was centrifuged and filtered to produce 2 kg of clear supernatant with a lactic acid concentration of 70 g / L. 50% of the supernatant (1 kg) was concentrated to a lactate concentration of 120 g / L using a rotary evaporator. The resulting concentrate was transferred to a 0.5 L reactor preheated to 80° C. and stirred at 300 RPM. The remaining 50% of the supernatant (1 kg) was added to a separate vessel that had been heated to 60° C. and connected to the reactor with a peristaltic pump. The concentrate was reduced in vacuum (180 mbar) at a rate of 100 g / h until a total concentration factor of 80% (200 g) was reached. The internal temperature during crystallization was maintained at 58° C. Then the supernatant was added at a rate of 80 g / L while maintaining an 80% evaporation ratio. After 12.5 hours, the entire supernatant was added. The reactor was then left stirring at 60° C. and atmospheric pressure for 7 hours. The crystals were collected and filtered using a sintered glass funnel. The obtained crystals were washed with cold water and dried at 70° C. Yield: 43%, Assay: 96.3%. The crystals were characterized for their particle size distribution through sieving. The results are shown in FIG. 9. The crystals were observed under an optical microscope. FIG. 10 shows an image of the crystals remaining on the top of the 25 μm sieve.

[0093] Example 10. Magnesium lactate dihydrate was obtained from the decomposition of polylactic acid (PLA 4032D) using sodium hydroxide to obtain a sodium lactate slurry. Sodium ions were replaced with magnesium ions by adding magnesium sulfate as described in WO 2021 / 165964. Magnesium lactate dihydrate was then added to a 3-neck round bottom flask equipped with a condenser and dissolved in DW at 100°C. Any undissolved impurities were filtered using a sintered glass funnel. The resulting 580 g of clear solution (10.7% lactic acid) was transferred to a 0.5 L reactor preheated to 100°C. The solution was boiled and the water was evaporated for 20 hours, removing a total of 320 g. The crystals were then collected and filtered using a sintered glass funnel. The resulting crystals were dried at 70°C. Yield: 57.5%, Assay: 97.0%, % D-lactate: 0.5%, Original crystal assay: 86.4%; Original D-lactate: 1.5%. The crystals were characterized for their size distribution through sieving. The results are shown in Figure 11. The crystals were observed under an optical microscope. Figure 12 shows an image of the crystals remaining on top of the 200 μm sieve.

[0094] Example 11. Magnesium lactate dihydrate was obtained from the decomposition of polylactic acid (table waste) using sodium hydroxide to obtain a sodium lactate slurry. Sodium ions were replaced with magnesium ions by adding magnesium sulfate as described in WO 2021 / 165964. Magnesium lactate dihydrate was added to a 3-neck round bottom flask equipped with a concentrator and dissolved in DW at 100°C. Any undissolved impurities were filtered using a sintered glass funnel. The resulting 500 g of clear solution (8.8% LA) was transferred to a 0.5 L reactor preheated to 100°C. The solution was boiled and the water was evaporated for 29 hours, removing a total of 336 g. The crystals were then collected and filtered using a sintered glass funnel. The resulting crystals were washed with cold water and dried at 70°C. Yield: 70.7%, Assay: 98.0%, %D-lactate: 0.6%, Original crystal assay: 82.1%; Original D-lactate: 3.8%. The crystals were characterized for their particle size distribution through sieving. The results are shown in Figure 13. The crystals were observed under an optical microscope. Figure 14 shows an image of the crystals remaining on top of the 300 μm sieve.

[0095] Comparative Example Magnesium lactate dihydrate was obtained from lactic acid fermentation broth using evaporative crystallization at 30°C. In particular, the lactic acid (LA) fermentation broth was centrifuged and filtered to produce 1 kg of clear supernatant with 7% LA. The supernatant was maintained at 30°C by applying a vacuum at 30-40 mbar until a lactate concentration of 12% was reached. The concentrated supernatant was transferred to a 0.5 L reactor preheated to 30°C, stirred at 300 RPM, and then concentrated again under vacuum (35-40 mbar) to remove 77% of the water. The crystals were then collected and filtered using a sintered glass funnel. Original %D-lactate: 6.8%, %D-lactate in mother liquor: 6.0%, yield: 88%, assay: 84.6%. The resulting crystals were washed with cold water and dried at 70°C. The yield decreased to 54% and the assay increased to 99.8%. Thus, contrary to the crystallization of magnesium L-lactate at temperatures in the range of about 50-100°C according to embodiments of the present invention, crystallization at 30°C did not result in an increase in the D-lactate content in the mother liquor compared to the initial value. The D-lactate content in the mother liquor was rather decreased, resulting in crystals with the same ratio of D-lactate to L-lactate as the original filtered broth. Also, the crystals obtained were very small and would not be very suitable for de novo PLA production (Figures 15-16).

[0096] The preceding description of specific embodiments will make fully apparent the general nature of the invention, in that others, by applying current knowledge, may easily modify and / or adapt such specific embodiments to various applications without undue experimentation and without departing from the general concept, and such adaptations and modifications should and are intended to be understood within the meaning and equivalents of the disclosed embodiments. It should be understood that the phraseology or terminology used herein is for purposes of description and not limitation. The means, materials, and steps for carrying out various disclosed functions may take a wide variety of alternative forms without departing from the invention.

Claims

1. 1. A process for the formation of high purity magnesium L-lactate crystals from decomposing organic waste, comprising: a. providing a clarified dispersion of decomposed organic waste containing lactate at a concentration of about 50 to about 110 g / L; b. optionally, concentrating the clarified dispersion of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified dispersion of step (a) or the concentrated clarified dispersion of step (b) to obtain a suspension containing seed magnesium L-lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium L-lactate crystals; and e. Recovering the magnesium L-lactate crystals obtained in step (d). Including, A process wherein steps (b) to (d) are carried out at an elevated temperature in the range of about 50° C. to about 90° C. and with an applied vacuum to a pressure of about 80 to about 300 mbar.

2. 2. The process of claim 1, wherein the clarified dispersion of decomposed organic waste comprises decomposed organic waste from which impurities have been removed using at least one of filtration, centrifugation, flotation, sedimentation, coagulation, flocculation, and decantation, or the organic waste is selected from food waste, municipal food waste, household food waste, agricultural waste, industrial food waste from food processing facilities, commercial food waste, and mixtures or combinations thereof.

3. The process of claim 1, wherein the decomposed organic waste comprises fermentation broth, preferably the fermentation broth is obtained from a fermentation process of a carbohydrate source or the fermentation broth is obtained from a fermentation process of an organic waste feedstock.

4. 4. The process of any one of claims 1 to 3, wherein step (b) is carried out to a lactate concentration of about 100 to about 130 g / L.

5. 5. The process of any one of claims 1 to 4, wherein the mixing in step (c) is carried out at a speed of about 50 to about 300 revolutions per minute (RPM), or the mixing in step (c) is carried out for at least 1 hour.

6. 6. The process of any one of claims 1 to 5, wherein steps (b) to (d) are carried out at an elevated temperature in the range of about 50°C to about 80°C, or steps (b) to (d) are carried out with the application of a vacuum to a pressure of about 150 to about 250 mbar.

7. 7. The process of any one of claims 1 to 6, wherein step (d) is carried out at an evaporation rate of about 2 to about 5 wt % per hour, or step (e) comprises filtration and / or centrifugation, or step (e) is carried out at room temperature.

8. The process according to any one of claims 1 to 7, further comprising a step (f) of washing the obtained magnesium L-lactate crystals, preferably wherein washing the obtained magnesium L-lactate crystals is carried out in a solvent selected from water, ethanol, propanol, isobutanol, cyclohexane, acetone, ethyl acetate, and mixtures or combinations thereof.

9. 9. The process according to any one of claims 1 to 8, further comprising a step (g) of drying the magnesium L-lactate crystals to a loss on drying (LOD) % of about 10% to about 20%, preferably wherein drying is carried out at an elevated temperature of about 50°C to about 120°C.

10. 10. The process of any one of claims 1 to 9, wherein the obtained magnesium L-lactate crystals are solubilized and recrystallized by repeating steps (c) to (e) multiple times, or wherein the obtained magnesium L-lactate crystals are characterized by a median size smaller than 75 μm, or wherein the obtained magnesium L-lactate crystals are characterized by a median size greater than 75 μm, or wherein the obtained magnesium L-lactate crystals are characterized by a particle size distribution comprising a median size in the range of about 100 to about 300 μm.

11. The process of claim 1, wherein the recovery rate of the magnesium L-lactate crystals is at least 90%.

12. 12. The process of any one of claims 1 to 11, wherein the obtained magnesium L-lactate crystals contain less than 3% magnesium D-lactate, preferably less than 2% magnesium D-lactate, more preferably less than 1.5% magnesium D-lactate, and most preferably less than 1% magnesium D-lactate.

13. A plurality of magnesium L-lactate crystals obtainable by the process according to any one of claims 1 to 12.

14. 1. A process for enriching the L-lactate enantiomer from an enantiomeric mixture derived from decomposing organic waste, comprising: a. providing a clarified dispersion of decomposed organic waste containing lactate salts, the lactate salts comprising an enantiomeric mixture of D- and L-lactate salts, at a concentration of about 50 to about 110 g / L; b. optionally, concentrating the clarified dispersion of step (a) to a lactate concentration of about 100 to about 150 g / L; c. mixing the clarified dispersion of step (a) or the concentrated clarified dispersion of step (b) to obtain a suspension containing seed magnesium lactate crystals; d. removing about 70% to about 90% of the water from the suspension of step (c) to obtain magnesium L-lactate crystals having enriched enantiomeric purity; and e. Recovering the magnesium L-lactate crystals obtained in step (d). Including, A process wherein steps (b) to (d) are carried out at an elevated temperature in the range of about 50° C. to about 90° C. and with an applied vacuum to a pressure of about 80 to about 300 mbar.

15. 15. The process of claim 14, wherein the resulting magnesium L-lactate crystals contain less than 1% magnesium D-lactate.

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