NON PURIFIED GLYCEROL

Abstract

A process including the steps of: providing a glycerol rich-fraction as carbon source to a fermentation medium; fermenting the fermentation medium by means of a microorganism capable of producing propionic acid in the presence of a caustic salt to provide a fermentation broth including a propionic acid salt; and recovering propionic acid salt from the fermentation broth, wherein the glycerol rich-fraction is derived from a process including the steps of: subjecting the glycerol fraction to an evaporative crystallization step to form a distillate fraction including water, and a residue fraction including glycerol and solid salts; and subjecting the residue fraction to a salt removal step, resulting in a salt fraction and a glycerol-rich fraction. The process allows the manufacture of a propionic acid salt using a glycerol-rich carbon source without problems in down-stream processing, and without need for cost-intensive purification steps for the glycerol.

Claims

1. Process comprising the steps of providing a glycerol rich-fraction as carbon source to a fermentation medium; fermenting the fermentation medium by means of a microorganism capable of producing propionic acid in the presence of a caustic salt to provide a fermentation broth comprising a propionic acid salt, and recovering propionic acid salt from the fermentation broth, wherein the glycerol rich-fraction is derived from a process comprising the steps of subjecting a glycerol fraction comprising glycerol, inorganic salts, and water, to an evaporative crystallization step to form a distillate fraction comprising water and a residue fraction comprising glycerol and solid salts, subjecting the residue fraction to a salt removal step, resulting in a salt fraction and a glycerol-rich fraction.

2. Process comprising the steps of providing a glycerol fraction comprising glycerol, inorganic salts, and water, subjecting the glycerol fraction to an evaporative crystallization step to form a distillate fraction comprising water, and a residue fraction comprising glycerol and solid salts, subjecting the residue fraction to a salt removal step, resulting in a salt fraction and a glycerol-rich fraction, providing the glycerol rich-fraction as carbon source to a fermentation process wherein a fermentation medium is fermented by means of a microorganism capable of producing propionic acid in the presence of a caustic salt to provide a fermentation broth comprising a propionic acid salt, and recovering propionic acid salt from the fermentation broth.

3. Process according to claim 1 wherein the glycerol fraction comprising glycerol, inorganic salt, and water has an inorganic salt content of 2-15 wt. %.

4. Process according to claim 1, wherein the glycerol fraction comprising glycerol, inorganic salt, and water has a water content of 1-30 wt. %.

5. Process according to claim 1, wherein the glycerol fraction to be subjected to the evaporative crystallization step is obtained from a MONG removal step, wherein a glycerol fraction comprising 5-35 wt. %, of MONG is subjected to a MONG removal step to form a glycerol-rich fraction, and a MONG-rich fraction, the MONG removal step comprising a centrifugation step.

6. Process according to claim 5, wherein the MONG content of the glycerol rich fraction is in the range of 0-10 wt. %.

7. Process according to claim 1, wherein the glycerol-rich fraction resulting from the salt removal step comprises less than 5 wt. % of the total of water and methanol.

8. Process according to claim 1, wherein the glycerol-rich fraction resulting from the salt removal step is provided directly to the fermentation step.

9. Process according to claim 1, wherein the glycerol-rich fraction resulting from the salt removal step has a MONG content of at least 5 wt. %, e.g., between 5 and 35 wt. %, and is submitted to a MONG removal step to form a glycerol-rich fraction and a MONG-rich fraction, wherein the glycerol-rich fraction is provided to the fermentation step, wherein the MONG removal step is a centrifugation step.

10. Process according to claim 9, wherein the MONG content of the glycerol rich fraction formed in the MONG removal step is in the range of 0-10 wt. %.

11. Process according to claim 1, wherein the propionic acid salt is selected from the group of calcium propionate, magnesium propionate, potassium propionate, and sodium propionate.

12. Process according to claim 1, wherein the step of recovering propionic acid salt from the fermentation broth encompasses the sequential steps of biomass removal, optional purification with activated carbon, an optional concentration step, and spray drying.

13. Process according to claim 1, wherein the step of recovering propionic acid salt from the fermentation broth encompasses the sequential steps of biomass removal, optional purification with activated carbon, a concentration step, a precipitation step wherein contaminants are precipitated, and a precipitation step wherein a propionic acid salt is precipitated.

14. Process according to claim 1, wherein the step of recovering propionic acid salt from the fermentation broth encompasses the sequential steps of biomass removal, optional purification with activated carbon, an optional concentration step, an acidification step, and an extraction step.

15. A glycerol rich-fraction as carbon source in a fermentation process, wherein a fermentation medium is fermented by means of a microorganism capable of producing propionic acid in the presence of a caustic salt to provide a fermentation broth comprising a propionic acid salt, wherein the glycerol rich-fraction is derived from a process comprising the steps of subjecting the glycerol fraction to an evaporative crystallization step to form a distillate fraction comprising water and a residue fraction comprising glycerol and solid salts, subjecting the residue fraction to a salt removal step, resulting in a salt fraction and a glycerol-rich fraction.

Description

EXAMPLE 1

[0087] A glycerol purification process was developed using a computer model. The model gave the following results: A starting glycerol fraction was submitted to evaporative crystallization. The crystallization conditions included a temperature of 120 C., and a flash-pressure reduction to 10 mbar. The evaporative crystallization yielded a top fraction comprising water and methanol, and a residue fraction comprising glycerol and solid salts. The residue fraction was centrifuged to form a salt-containing slurry fraction, and a glycerol-rich fraction. The composition of the various fractions is presented in Table 1.

TABLE-US-00001 TABLE 1 salt- starting glycerol containing glycerol rich top slurry Component fraction fraction fraction fraction glycerol (wt. %) 75.3 85.4 0.0 8.5 water (wt. %) 6.2 1.1 85.0 0.1 methanol (wt. %) 0.9 0.0 15.0 0.0 K2SO4 (wt. %) 6.0 0.4 0.0 90.0 MONG (wt. %) 11.5 13 0 1.3 total (wt. %) 100.0 100.0 100.0 100.0

[0088] The glycerol-rich product resulting from the evaporative crystallization step can be provided as carbon source to a fermentation process for the production of propionic acid. Optionally, the glycerol-rich fraction can be submitted to a centrifugation step to form a MONG-rich fraction and a glycerol fraction with reduced MONG content which is then provided to the fermentation step.