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EP-4736977-A2 - CRYSTALLIZATION OF HIGH-PURITY MAGNESIUM L-LACTATE

EP4736977A2EP 4736977 A2EP4736977 A2EP 4736977A2EP-4736977-A2

Abstract

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

Inventors

  • GREENER, TSVIKA
  • Papo, Nitsan
  • HARNOY, Assaf

Assignees

  • TripleW Ltd.

Dates

Publication Date
20260506
Application Date
20220119

Claims (15)

  1. A process for the formation of high-purity magnesium L-lactate crystals from decomposed organic waste, the process comprising the steps of: a. providing a clarified dispersion of decomposed organic waste comprising a lactate salt in a concentration of about 50 to about 110 g/L; b. optionally concentrating the clarified dispersion of step (a) to a lactate salt 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 comprising seed magnesium L-lactate crystals; d. removing from about 70% to about 90% of water from the suspension of step (c) to obtain magnesium L-lactate crystals; and e. collecting the magnesium L-lactate crystals obtained in step (d), wherein steps (b) through (d) are performed at elevated temperature in the range of about 50°C to about 90°C and the application of a vacuum to a pressure of about 80 to about 300 mbar.
  2. The process according to 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 wherein the organic waste is selected from food waste, municipal food waste, residential food waste, agricultural waste, industrial food waste from food processing facilities, commercial food waste, and a mixture or combination thereof.
  3. The process according to claim 1, wherein the decomposed organic waste comprises a fermentation broth, preferably wherein the fermentation broth is obtained from a fermentation process of a carbohydrate source or wherein the fermentation broth is obtained from a fermentation process of an organic waste feedstock.
  4. The process according to any one of claims 1 to 3, wherein step (b) is performed to a lactate salt concentration of about 100 to about 130 g/L.
  5. The process according to any one of claims 1 to 4, wherein the mixing in step (c) is performed at a speed of about 50 to about 300 rounds per minute (RPM); or wherein the mixing in step (c) is performed for at least 1 hour.
  6. The process according to any one of claims 1 to 5, wherein steps (b) through (d) are performed at elevated temperature in the range of about 50°C to about 80°C; or wherein steps (b) through (d) are performed with the application of a vacuum to a pressure of about 150 to about 250 mbar.
  7. The process according to any one of claims 1 to 6, wherein step (d) is performed at an evaporation rate of about 2 to about 5 wt% per hour; or wherein step (e) comprises filtration and/or centrifugation; or wherein step (e) is performed at room temperatures.
  8. The process according to any one of claims 1 to 7, further comprising step (f) of washing the obtained magnesium L-lactate crystals, preferably wherein washing of the obtained magnesium L-lactate crystals is performed in a solvent selected from water, ethanol, propanol, isobutanol, cyclohexane, acetone, ethyl acetate, and a mixture or combination thereof.
  9. The process according to any one of claims 1 to 8, further comprising 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 performed at elevated temperatures of about 50°C to about 120°C.
  10. The process according to any one of claims 1 to 9, wherein the obtained magnesium L-lactate crystals are solubilized and re-crystalized by reiterating steps (c) to (e); 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 larger than 75 µm; or wherein the obtained magnesium L-lactate crystals are characterized by a size distribution comprising a median size in the range of about 100 to about 300 µm.
  11. The process according to any one of claims 1 to 10, wherein the recovery of magnesium L-lactate crystals is at least 90%.
  12. The process according to any one of claims 1 to 11, wherein the obtained magnesium L-lactate crystals comprise 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 of any one of claims 1 to 12.
  14. A process for enriching L-lactate enantiomer from an enantiomeric mixture derived from decomposed organic waste, the process comprising the steps of: a. providing a clarified dispersion of decomposed organic waste comprising a lactate salt comprising an enantiomeric mixture of D- and L-lactate in a concentration of about 50 to about 110 g/L; b. optionally concentrating the clarified dispersion of step (a) to a lactate salt 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 comprising seed magnesium lactate crystals; d. removing from about 70% to about 90% of water from the suspension of step (c) to obtain magnesium L-lactate crystals with enriched enantiomeric purity; and e. collecting the magnesium L-lactate crystals obtained in step (d), wherein steps (b) through (d) are performed at elevated temperature in the range of about 50°C to about 90°C and the application of a vacuum to a pressure of about 80 to about 300 mbar.
  15. The process according to claim 14, wherein the obtained magnesium L-lactate crystals comprise less than 1% magnesium D-lactate.

Description

FIELD OF THE INVENTION The present invention relates to a process for the crystallization of high purity magnesium L-lactate from decomposed organic waste. BACKGROUND OF THE INVENTION Lactic acid is the most widely occurring hydroxycarboxylic acid with applications in 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 should be taken to avoid endogenous decrease in pH due to the formation of lactic acid in order to maintain the productivity of the microorganisms. A pH in the range of 5-7 is preferable and can be obtained by the addition of bases such as ammonium -, sodium -, potassium -, magnesium - or calcium hydroxides that neutralize the lactic acid thereby producing a lactate salt. In order to convert the lactate salt to lactic acid, a re-acidification step using e.g., sulfuric acid can be performed. Approximately 60-80% of the production costs of lactic acid can result from downstream processes, including the purification, concentration, and separation of the lactic acid/lactate salt from the fermentation broth. Additionally, reducing or eliminating the production of by-products (such as salts other than lactate) is desirable. Various methods have been previously proposed for recovering and purifying lactic acid and/or lactate salts from fermentation broths. 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. The crystallization was conducted 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 yield of fermentation coupled with in situ product removal (ISPR) reached 143 g L-1, 2.41 g L-1h-1 and 94.3%, respectively. U.S. Patent No. 9,689,007 describes a method for producing lactate or lactic acid from "low sugar" plant extracts via fermentation, comprising providing a fermentation medium that includes at least 25wt.% of a plant extract containing fermentable carbohydrates, and fermenting the fermentation medium by means of a lactic acid producing microorganism in the presence of a caustic magnesium salt to provide a fermentation broth containing at the most 9.5wt.% magnesium lactate at the end of fermentation, the magnesium lactate being in soluble form during and at the end of fermentation. To achieve a magnesium lactate concentration in the fermentation broth at the end of fermentation which is at most 9.5wt.%, the fermentation medium comprising the plant extract preferably contains fermentable carbohydrates in a concentration of at most 9.5wt.%. U.S. Publication No. 2014/0012041 describes a method of producing a lactic acid salt comprising: subjecting an aqueous lactic acid salt solution comprising a formic acid salt in an amount of not less than 7.0% by weight with respect to said lactic acid salt to crystallization, and recovering said lactic acid salt. The lactic acid salt concentration in said aqueous lactic acid salt solution is 10.0 to 30.0% by weight. U.S. Publication No. 2017/0218408 describes a method for preparing a fermentation product including lactic acid, the method including: a) treating a lignocellulosic material, being in a particulate state and having an average particle size of from 0.1 to 250 mm, with caustic magnesium salt in the presence of water to provide 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 carbohydrate 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 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 the fermentation are carried out simultaneously. The feedstock for the process of U.S. Publication No. 2017/0218408 is a lignocellulosic material, which includes materials containing cellulose, hemicellulose and lignin, such as may be derived from plant biomass. Preferred lignocellulosic materials are selected from the group consisting of: wheat straw, sugarcane bagasse, corn stover, and mixtures thereof. WO Publication No. 2017/178426 describes a fermentation process for producing magnesium lactate from a carbon source comprising the steps of: providing a fermentation medium comprising a fermentable carbon source in a fermentation reactor,fermenting