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 pH decrease resulting from lactic acid fermentation in order to maintain microbial productivity. A pH in the range of 5 to 7 is preferred and can be achieved by the addition of a base, such as ammonium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, or calcium hydroxide, which neutralizes lactic acid and thereby produces lactate. A reacidification step, for example, using sulfuric acid, can be performed to convert lactate to lactic acid.

[0003] Approximately 60-80% of lactic acid production costs 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 previously been proposed for recovering and purifying lactic acid and / or lactate from fermentation broth. For example, a process for purifying magnesium lactate 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] U.S. 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 fermentation, the magnesium lactate being in a soluble form during and at the end of fermentation. To achieve a magnesium lactate concentration in the fermentation broth of up to 9.5 wt.% at the end of fermentation, the fermentation medium containing the plant extract preferably contains fermentable carbohydrates at a concentration of up to 9.5 wt.%.

[0006] U.S. Patent Application Publication No. 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, wherein the concentration of lactate in the aqueous lactate solution is 10.0 to 30.0% by weight.

[0007] U.S. Patent Application Publication No. 2017 / 0218408 describes a method for preparing a fermentation product containing lactic acid, the method comprising: a) treating particulate lignocellulosic material, having an average particle size of 0.1 to 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 containing 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 containing magnesium lactate and the solid lignocellulosic fraction; and d) recovering the magnesium lactate from the broth, wherein the saccharification and fermentation are carried out simultaneously. The feedstock for the process of U.S. Patent Application Publication No. 2017 / 0218408 is 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 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, including: 12sugars) and / or their polymers.

[0009] WO 2017 / 207501 describes a method for separating biomass from a solid fermentation product, in which a slurry containing biomass and solid fermentation product is provided to the top of a biomass separator unit, an aqueous medium is provided to the bottom of the biomass separator unit, while a product stream containing the solid fermentation product is withdrawn from the bottom of the biomass separator unit, and a waste stream containing biomass is withdrawn from the top of the biomass separator unit. The solid fermentation product is a fermentation product 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 soluble and insoluble impurity contents. However, there is a need to utilize more readily available 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. Fermentation broths derived from such heterogeneous feedstocks cannot be effectively processed by currently available methods to obtain high-purity magnesium L-lactate products in a cost-effective manner.

[0011] WO 2020 / 110108 states: (a) providing a clarified fermentation broth from which insoluble impurities have been removed, the clarified fermentation broth 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 degradation products containing lactic acid and / or lactate. The process of the present invention utilizes fermentation broth or other organic waste degradation products from a variety of sources, including evaporative crystallization, which can make 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 D-lactic acid removal during and / or after fermentation. The process involves the use of evaporative crystallization under specific conditions that produces high-purity magnesium L-lactate crystals even after a single 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. Therefore, the process of the present invention provides a simple and economical method for producing 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 an applied 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 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 an applied 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) through (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, within the specified ranges.

[0025] According to a further embodiment, 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 another embodiment, steps (b) through (d) are carried out by applying a vacuum to a pressure of about 150 to about 250 mbar, inclusive. According to a further embodiment, steps (b) through (d) are carried out by applying a 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 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) through (e) multiple times. According to these embodiments, steps (c) through (e) are carried out for, for example, between 2 and 6 cycles, inclusive, with each cycle 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 less than 75 μm. According to certain embodiments, the resulting magnesium L-lactate crystals are characterized by a particle size distribution comprising a median size in the range of about 20 to about 100 μm, inclusive of each value 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 comprising a median size in the range of about 100 to about 300 μm, inclusive of each value 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 the L-lactate enantiomer from an enantiomeric mixture derived from decomposing organic waste, the process comprising: providing a clarified dispersion of decomposed organic waste containing lactate salts, including 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 an applied 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 explanation 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. [Figure 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. [Figure 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 with cutoff sizes of 710 μm (4A), 500 μm (4B), 300 μm (4C), 100 μm (4D), and 75 μm (4E). Figure 4F shows an optical microscope image of magnesium L-lactate crystals that passed through the 75 μm sieve. [Figure 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] Figure 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 substitution 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 substitution 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 using 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 substitution of magnesium lactate obtained from degraded PLA using sodium hydroxide. [Figure 15] FIG. 15 shows the particle size distribution of magnesium L-lactate crystals obtained from the 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 INVENTION

[0040] The present invention provides a process for the formation of magnesium L-lactate crystals from fermentation broth or other organic waste decomposition products, which can 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, and can be easily manipulated with desirable filterability and particle size distribution, making it particularly advantageous for use in subsequent polylactic acid formation.

[0041] According to some aspects and embodiments, a clarified dispersion of decomposed organic waste or fermentation broth is obtained, wherein the clarified dispersion or broth contains 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 the degradation product of any lactic acid-containing waste, such as, but not limited to, polylactic acid polymers that have been subjected to hydrolysis. According to other embodiments, a fermentation broth derived from an organic waste feedstock is used. Organic waste feedstocks 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 originate from residues ranging from animal and human waste, vegetable and fruit residues, plants, prepared foods, protein residues, slaughter waste, and combinations thereof. Each possibility represents a separate embodiment. Industrial organic food waste can include industrial waste such as by-products, factory rejects, market returns, or inedible food part waste (such as skin, fat, crusts, and peels). 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 heterogeneous 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 fragments, hair, precipitated salts, cellular debris, fiber (e.g., fruit and / or vegetable peelings), 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, residue 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 fragments, 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 than 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 than 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 decomposition waste. Impurities may be removed before and / or after decomposition or fermentation of the waste to produce a clarified liquid. According to certain embodiments, separation of insoluble impurities is carried out before decomposition or fermentation. For example, in some embodiments, complex organic waste may be heat-treated, followed by enzymatic treatment, followed by centrifugation, e.g., decanter centrifugation, to remove most of the insoluble impurities. The supernatant (still containing some impurities) is pumped into a vessel or fermenter for lactic acid production.

[0046] According to various embodiments, separation of the majority of 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 decomposed organic waste from which insoluble impurities have been removed using filtration (e.g., microfiltration) and / or centrifugation.

[0047] Although not required to obtain a clarified dispersion or broth in accordance with 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 substantially different from the desired lactic acid product, such as salts and proteins. Each possibility represents a separate embodiment. Further purification may be carried out to remove contaminants with similar physical and chemical properties, using, for example, 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 feedstream-derived fermentation broth with a relatively low content of solid impurities, and some of these methods utilize crystallization and / or maintaining lactate in a particulate form during the fermentation step. Furthermore, some known methods are designed to use a specific amount of carbohydrate in the feedstream 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 fermentation should contain a maximum of 9.5 wt.% magnesium lactate.

[0049] While the present invention allows for the production of high-purity magnesium L-lactate from homogeneous biomass-based feed streams, it also advantageously allows for the production of high-purity magnesium L-lactate 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 derived from complex feedstocks, which 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 discovered 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 the amount of fermentable sugars in the initial organic feedstock.

[0050] The present invention advantageously allows for the production of high-purity magnesium L-lactate crystals from heterogeneous feedstocks with high yields and enantiomer separation. Surprisingly, for the first time, it has been disclosed 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, such as in dairy products. The present invention advantageously allows for the production of high-purity magnesium L-lactate crystals from decomposed organic waste containing 10 wt.% or less of 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 lactate ion concentration is optionally increased to a range of about 100 to about 150 g / L, inclusive of each value within the specified range. Preferably, lactate ions are concentrated to a concentration of about 100 to about 130 g / L, inclusive of each value within the specified range. Exemplary concentrations of lactate 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, 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, from about 50°C to about 90°C, inclusive, and applying a vacuum to a pressure of about 80 to about 300 mbar.

[0052] The 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 an applied vacuum 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, inclusive. 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, 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 by 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 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 335 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 4 This 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 evaporation rate is within the range of about 2 to about 5% weight loss per hour, inclusive of each value within the specified range. 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. 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 enantiomeric purity. Without being bound by any theory or mechanism of action, it is believed that D-lactate crystals adhere to the surface of the magnesium L-lactate crystals, thereby allowing them to be 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, the method comprising washing magnesium L-lactate crystals obtained from magnesium L-lactate crystallization with an aqueous solution at elevated temperature and reduced pressure. 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, 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 a 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 include 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 values within the specified ranges, and applying a vacuum to a pressure of about 80 to about 300 mbar, as detailed above. This solubilization and recrystallization can be carried out for additional cycles as needed to achieve the required crystal purity, 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 a single cycle may be sufficient as disclosed herein due to the improved purity of the resulting magnesium L-lactate crystals.

[0059] The resulting recovery of magnesium L-lactate crystals 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 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 a further embodiment, 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 enantiomer enrichment for enriching the L-lactate enantiomer from the enantiomeric mixture of D- and L-lactate monomers. This enrichment is particularly useful for recycling lactic acid. Enrichment of the L-lactate enantiomer by the processes of the present invention can be 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 enantiomeric mixture containing 90% L-lactate and 10% D-lactate, a 10% enrichment 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 processes 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 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. As used herein, the term "particle size" 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 monomodal, bimodal, or trimodal, with a median particle size within the range of about 20 to 100 μm, or about 100 to about 300 μm, including each value within the specified range. As used herein, the terms "median" and "d" interchangeably refer to the particle size distribution. 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 at which half of the particles have a diameter smaller than this value and half of the particles have a diameter larger than this value. Thus, the resulting median particle size of magnesium L-lactate crystals is typically 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 process disclosed herein is primarily designed to produce high purity magnesium L-lactate crystals, the same process 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 an applied 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 containing a lactate salt comprising a mixture of enantiomers 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 an applied 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 forms 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 certain embodiments of the present invention, but they should in no way be construed as limiting the broad scope of the invention. Those skilled in the art can readily devise numerous variations and modifications of the principles disclosed herein without departing from the scope of the invention.

[0071] Example Example 1 Fermentation of 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 was reached. 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 Buchner funnel equipped 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 Figure 1 and Table 1.

[0073] [Table 1]

[0074] The crystals were observed under an optical microscope. Figures 2A-2F show that the crystals exhibited 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 Figure 3 and Table 2, and optical microscope images of the crystals are shown in Figures 4A-4F.

[0076] [Table 2]

[0077] Example 4. Fermentation of 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 was reached. 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 Buchner funnel equipped 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%, resulting in a D / L-lactate ratio of 1.6% / 98.4% in the magnesium lactate crystals. The resulting magnesium lactate crystals were redissolved to a final concentration of 110 g / L, and the solution was treated with activated carbon 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 equipped 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 profiles are presented in Figure 5 and Table 3.

[0079] [Table 3]

[0080] As is clear 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. Furthermore, 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, designated "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 by 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 yielded 4-5% less water than the slow or fast evaporation rates and showed the best results in terms of filterability. This rate also produced the highest purity and lowest % D-lactate crystals. A downward trend in the overall crystallization yield was detected at fast evaporation rates.

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

[0087] [Table 6]

[0088] These results suggest that intermediate 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 intermediate evaporation rate crystallization compared to crystallization at slow or fast evaporation rates. The particle size distribution of the resulting crystals was also evaluated using sieves with different cutoffs. The results suggested that intermediate rate crystallization produced the largest crystals, with >75% of the crystals being larger than 100 μm. The results are shown in Figure 6. However, it should be noted that particle size distributions based on sieving are less accurate due to the tendency of 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 under 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, an intermediate crystallization rate of 2.4 to 4.8 wt% per hour and evaporation occurring for 8 to 16 hours provided the best results.

[0091] Example 8 A constant-weight fed-batch crystallization was carried out. The lactic acid fermentation broth was centrifuged and filtered to produce 2 kg of clear supernatant with 7% lactic acid. 20% (0.4 kg) of the supernatant 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 at a rate of 80 g / h under vacuum (280 mbar). During evaporation, the supernatant was added at the same rate. The internal temperature during crystallization was maintained at 70°C. After 20 h, when all the supernatant had been added, the crystals were collected and filtered using a sintered glass funnel. The resulting 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 heated to 60°C and connected to the reactor with a peristaltic pump. The concentrate was reduced under 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. The supernatant was then added at a rate of 80 g / L, while maintaining an 80% evaporation rate. 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 Figure 9. The crystals were observed under an optical microscope. Figure 10 shows an image of the crystals remaining on 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. As described in WO 2021 / 165964, magnesium sulfate was added to replace sodium ions with magnesium ions. The magnesium lactate dihydrate was then added to a three-necked 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 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 particle 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 three-necked round-bottom flask equipped with a condenser and dissolved in DW at 100°C. Any undissolved impurities were filtered using a sintered glass funnel. 500 g of the resulting clear solution (8.8% LA) was transferred to a 0.5 L reactor preheated to 100°C. The solution was boiled and 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. Specifically, 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 of 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. The original % D-lactate was 6.8%, the % D-lactate in the mother liquor was 6.0%, the yield was 88%, and the assay was 84.6%. The resulting crystals were washed with cold water and dried at 70°C. The yield decreased to 54%, while 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. Rather, the D-lactate content in the mother liquor decreased, resulting in crystals with the same ratio of D-lactate to L-lactate as the original filtered broth. Additionally, the resulting crystals were very small and likely not 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 readily modify and / or adapt such specific embodiments to various uses 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 range of 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; a. providing a clarified dispersion of decomposed organic waste containing lactate at a concentration of 50-110 g / L; b. optionally concentrating the clarified dispersion of step (a) to a lactate concentration of 100-150 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 70% to 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 50°C to 90°C and with an applied vacuum to a pressure of 80 to 300 mbar.

2. 10. 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. 10. The process of claim 1, wherein the decomposing organic waste comprises a fermentation broth.

4. The process described in claim 3, wherein 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.

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

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

7. 5. The process of any one of claims 1 to 4, wherein steps (b) to (d) are carried out at an elevated temperature in the range of 50°C to 80°C, or steps (b) to (d) are carried out with the application of a vacuum to a pressure of 150 to 250 mbar.

8. 5. The process of any one of claims 1 to 4, wherein step (d) is carried out at an evaporation rate of 2 to 5 wt % per hour, or step (e) comprises filtration and / or centrifugation, or step (e) is carried out at room temperature.

9. The process of any one of claims 1 to 4, further comprising a step (f) of washing the obtained magnesium L-lactate crystals.

10. The process of claim 9, wherein 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.

11. 5. The process of any one of claims 1 to 4, further comprising the step (g) of drying the magnesium L-lactate crystals to a loss on drying (LOD) % of 10% to 20%.

12. The process of claim 11, wherein drying is carried out at an elevated temperature of 50°C to 120°C.

13. 5. The process of any one of claims 1 to 4, 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 100 to 300 μm.

14. The process according to any one of claims 1 to 4, wherein the recovery rate of the magnesium L-lactate crystals is at least 90%.

15. 5. The process of any one of claims 1 to 4, wherein the obtained magnesium L-lactate crystals contain less than 3% magnesium D-lactate.

16. 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, including an enantiomeric mixture of D- and L-lactate salts, at a concentration of 50-110 g / L; b. optionally concentrating the clarified dispersion of step (a) to a lactate concentration of 100-150 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 70% to 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 50°C to 90°C and with an applied vacuum to a pressure of 80 to 300 mbar.

17. 17. The process of claim 16, wherein the resulting magnesium L-lactate crystals contain less than 1% magnesium D-lactate.

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