WO2011084002A2 - Method for producing organic acids from biomass - Google Patents

Abstract

The present invention relates to a method for producing organic acids from biomass, and more specifically relates to a method for producing various organic acids (volatile fatty acids) from land-based, freshwater-based, marine or biodegradable organic mixed biomass by using a high-density cell culture method, and then concentrating and distilling the same. The method for producing organic acids from biomass comprises the steps of: (a) producing organic acids by fermenting biomass; (b) concentrating the organic acids so produced by at least 30%; and (c) recovering the organic acids by fractional distillation of the concentrated organic acid. A method for isolating organic acids produced economically from biomass according to the present invention can be used to advantage in converting organic acids into fuel or compounds such as alcohols, esters and alkanes in addition to the economic use of organic acids.

Description

How to produce organic acids from biomass

The present invention relates to a method for producing an organic acid from biomass, and more particularly, to produce an organic acid (volatile fatty acid) from terrestrial, aquatic, marine or biodegradable organic mixed biomass by a high concentration cell culture method, and then Concentrates and distills to produce each organic acid.

Biofuel is a generic term for energy obtained by using biomass as a raw material, and is obtained through direct combustion, alcohol fermentation, methane fermentation, and the like. Biomass, a raw material of biofuel, is divided into sugar-based (sugar cane, sugar beet, etc.), starch-based (corn, potato, sweet potato, etc.), and wood-based (wood, rice straw, waste paper, etc.). In this case, raw materials can be converted into biofuels through a fermentation process that is followed by a relatively simple pretreatment process.However, in the case of starch and wood systems, biofuels are produced through fermentation process using saccharified liquid after proper pretreatment and saccharification process. can do. Wood-based materials can use waste wood in the form of urban waste or forest by-products scattered throughout the forest as raw materials, and there is no useful value as food, so the stability of supply and demand of raw materials can be secured, but the lignin removal pretreatment process must be accompanied in the process. Due to the increase in the process cost, due to the crystalline structure consisting of hydrogen bonds, which is a characteristic of the wood-based cellulose substrate has a disadvantage of low economical low glycation yield.

However, except for the wood-based biofuel production technology that is currently commercialized, it uses the sugar- or starch-based raw materials that humans can use as food. Supply-demand problems can occur, and economically, using grains is a problem in terms of raw material costs. Corn cultivation also requires significant amounts of pesticides and nitrogen fertilizers, as well as environmental disadvantages that severely corrode the soil compared to other crops. When growing plants on confined lands to produce biomass, cultivation of mixed types of plants is one way to increase productivity per unit area. When producing biofuels from biomass, targeting one biomass is not eco-friendly and economical. Therefore, a biofuel production process that can utilize mixed biomass is very important.

One such method is anaerobic digestion of mixed biomass such as organic waste to produce organic acids, recovery and separation of the mixed alcohol to produce mixed alcohols (Hong Chapel et al., Korea Patent Publication No. 10-0321678, Korean Patent Publication No. 10-2007-0035562, 10-2008-0016523 and 10-2009-0095622). Hallchapel et al. Proposed a process for removing lignin by long-term pretreatment of lignocellulose with lime or quicklime and oxygen and using it for the production of volatile organic acids, but they have to be pretreated for a long time to remove lignin. In addition, the problem of requiring a pretreatment place of a large space for performing the pretreatment and using the above method, it is not possible to separate the volatile organic acids composed of acetic acid, propionic acid, butyric acid, production of the desired composition is impossible and There was a problem that can only be produced in form.

Alkali, such as NaOH and ammonia, is used to remove lignin in addition to the pretreatment by lime, and acids such as high pressure steam, sulfuric acid, hydrochloric acid and nitric acid are used together with high temperature for hemicellulose decomposition. Methods can be used.

Volatile organic acids usually contain acetic acid, propionic acid, butyric acid as major components, each of which is a very useful chemical produced by petrochemicals. Therefore, the anaerobic digestion process can have high economic efficiency only by the effective separation of these volatile organic acids.

In addition, organic acid salts, particularly calcium salts, may be combined with each other to form ketones through thermal conversion, and ketones may be converted into secondary alcohols through a hydrogenation reaction. When the purified organic acid is combined with alcohol, an ester is formed, and when the hydrocracking ester is hydrolyzed, primary alcohol may be produced. These ketones, esters, primary or secondary alcohols and the like can be used as useful chemicals or transportation fuels.

However, the production of organic acids generally requires a large amount of alkali to neutralize these acids, most are produced at a low concentration of less than 2% (w / v), and in itself has a characteristic of inhibiting the growth of cells, high concentration Does not show high productivity. Therefore, in order to establish an economical process, an effective fermentation process of an organic acid is required along with an effective recycling of neutralizing substances, and development of an energy efficient process for concentrating low concentrations of organic acids is required.

Therefore, the present inventors have made diligent efforts to solve the above problems, and added a circulating pH regulator to a multi-stage bioreactor including a cell recirculation apparatus, anaerobic digestion of biomass to produce a high concentration of organic acid, and then mixed them. Concentrating more than 30% in the form of an organic acid salt, and when performing azeotropic distillation, it was confirmed that the pure organic acid can be separated and purified, to complete the present invention.

Summary of the Invention

An object of the present invention is to provide a method for efficiently producing and concentrating an organic acid from biomass, and then separating and purifying the desired pure organic acid.

In order to achieve the above object, the present invention comprises the steps of (a) fermenting biomass to produce an organic acid; (b) concentrating the produced organic acid to at least 30%; And (c) recovering the organic acid by fractional distillation of the concentrated organic acid.

In the present invention, the biomass is selected from the group consisting of plant biomass, animal biomass, municipal waste biomass, and mixtures thereof.

In the present invention, the step (a) is characterized in that the anaerobic digestion of the biomass in a multi-stage bioreactor comprising a cell recycling device.

In the present invention, the step (a) is calcium carbonate (CaCO ₃ ), ammonium bicarbonate (NH ₄ HCO ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), sodium sulfate (Na ₂ SO ₄ ), sodium hydroxide (NaOH), dolomite (Dolomite) and a mixture of a pH adjuster selected from the group consisting of these is added, characterized in that the fermentation at pH 5.0 ~ 8.0 conditions. .

In the present invention, the concentration of the organic acid to 30% or more is characterized in that water is removed from the fermentation broth or the organic acid is selectively extracted from the fermentation broth.

In the present invention, removing water from the fermentation broth is performed by a distillation method, the distillation method is a multi-effect distillation (MED), multiple flash distillation (MSF, Multiple Stage Flash distillation) and steam compression distillation It is characterized in that it is selected from the group consisting of (MVC, Mechanical Vapor Compression distillation).

In the present invention, removing the water from the fermentation broth is characterized in that the reverse osmosis (RO, Reverse Osmosis) or forward osmosis (FO, Forward Osmosis) is first performed, followed by distillation.

In the present invention, the selective extraction of the organic acid is (a) dioctylamine (DOA), trioctylamine (TOA), triaurylamine, Di-tridecylamine, Alamine 336, Aliquat 336 (main component: methyltrioctylammonium chloride), trioctylphosphine oxide (TOPO), (b) Methyl isobutyl ketone (MIBK), chloroform, octanol, dodecanol, n-alkanes, xylene, oleyl alcohol, kerosene, and mixtures thereof, selected from the group consisting of tributylphosphate (TBP) and mixtures thereof. The mixed solution of the diluent selected from is added to the culture solution to extract the organic acid, it is characterized in that it is carried out by the method of back extraction again.

In the present invention, the fractional distillation is characterized in that azeotropic distillation after adding an additive selected from the group consisting of ethyl acetate, iso-butyl acetate, n-butyl acetate and mixtures thereof to the concentrated organic acid.

Other features and embodiments of the present invention will become more apparent from the following detailed description and the appended claims.

1 is an explanatory diagram showing a process for producing an organic acid from biomass according to an embodiment of the present invention.

Figure 2 is a schematic diagram of a high concentration multi-stage continuous fermentation tank for organic acid production according to an embodiment of the present invention.

Figure 3 is an explanatory diagram showing a concentration process by the forward osmosis method of the water-soluble fermentation product according to an embodiment of the present invention.

4 is an explanatory diagram showing an organic acid extraction and back extraction process using an extraction solvent according to an embodiment of the present invention.

5 is a schematic diagram of a four-stage continuous fermenter for producing organic acids according to one embodiment of the present invention.

Figure 6 is a graph showing the concentration of the organic acid over time in the four-stage bioreactor.

Figure 7 is a graph showing the concentration of the organic acid by back extraction according to an embodiment of the present invention.

8 is an explanatory diagram showing a fractional distillation apparatus and a process of an organic acid according to an embodiment of the present invention.

Detailed Description of the Invention and Specific Embodiments

In the present invention, by removing water from the fermentation broth of terrestrial, aqueous, marine or biodegradable organic mixed biomass or selectively extracting organic acids, the organic acids can be concentrated to 30% or more and azeotropically distills the organic acids concentrated to 30% or more. It was intended to determine if it can be separated and purified to pure organic acids.

In the present invention, while producing an organic acid through a multi-stage continuous fermentation, the optimum fermentation conditions are established, water is removed by reverse osmosis, osmosis, distillation, or the like, or the organic acid is extracted using a solvent, followed by reverse extraction to concentrate the organic acid. After performing azeotropic distillation. As a result it was confirmed that the organic acid can be separated and purified by component.

Thus, in one aspect, the present invention comprises the steps of (a) fermenting the biomass to produce an organic acid; (b) concentrating the produced organic acid to at least 30%; And (c) recovering the organic acid by fractional distillation of the concentrated organic acid.

1 is an explanatory view showing a process for producing an organic acid from biomass according to an embodiment of the present invention.

As shown in FIG. 1, the biomass is fermented in an organic acid fermentation tank to produce an organic acid, and the produced organic acid may be highly concentrated by various methods such as membrane concentration and distillation, and then separated through fractional distillation.

In the present invention, the biomass is selected from the group consisting of plant biomass, animal biomass, municipal waste biomass, and mixtures thereof. The biomass is paper, paper products, waste paper, wood, particle board, sawdust, agricultural waste, sewage, silage, grasses, chaff, vargas, cotton, jute, hemp, flax, bamboo, sisal , Manila hemp, straw, corncob, corn trough, switchgrass, alfalfa, hay, rice husk, coconut hair, cotton, synthetic cellulose, seaweed, algae, sludge, food Organic wastes, such as a garbage and a manure, can be illustrated.

In the present invention, the step of fermenting the biomass to produce an organic acid can be carried out in a conventional bioreactor, but in a multi-stage bioreactor comprising a cell recirculation device for producing an organic acid from the biomass more economically and efficiently It is desirable to anaerobic digest biomass.

Anaerobic digestion is a process that has been used for the production of methane gas.It is an acidogenesis that decomposes mixtures of manure, food waste and grass into complex microbial groups to produce organic acids and hydrogen, and methanogenesis that converts the generated organic acids and hydrogen into methane. It is composed.

The multistage bioreactor including the cell recirculation apparatus may use a multistage CRTR bioreactor system equipped with an upstream packed tower cell recirculation apparatus described in Korean Patent No. 0834110, which is a prior patent of the present inventors.

Figure 2 is a schematic diagram of a high concentration multi-stage continuous fermentation tank for organic acid production according to an embodiment of the present invention. As shown in Figure 2, the multi-stage bioreactor recovers the cells by upstream filling tower, filtration membrane, centrifugation, sedimentation, aggregation, adsorption, etc. to reduce the escape of cells from the fermenter, and the multistage bioreactor The cell recirculator is coupled to the effluent site of each end or end stage, operating without the wash-out of the cells, each stage having a separate biomass inlet.

Therefore, each stage can be operated by Fed-batch, and the biodegradable material that takes a long time to decompose in biomass is removed from the lower layer of fermentation tank and put into reactor having a longer residence period, which is decomposed for a longer period of time to increase the yield of organic acid from biomass. It can increase. Stirring of the fermentation broth in the multi-stage bioreactor fermenter is circulated by the compression and injection device of the internal air and added or discharged as necessary, thereby minimizing unnecessary gas consumption, and hydrogen and carbon dioxide produced during fermentation may be reused by microorganisms. have.

In the case of anaerobic digestion of a medium containing a large amount of saccharides such as glucose, starch, food waste, algae, and woody liquor to produce organic acids, lactic acid contamination frequently occurs. Therefore, it is important to inhibit the formation of lactic acid during anaerobic digestion.

Therefore, the step of fermenting the biomass to produce an organic acid is calcium carbonate (CaCO ₃ ), ammonium bicarbonate (NH ₄ HCO ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), sodium carbonate ( PH adjuster selected from the group consisting of Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), sodium sulfate (Na ₂ SO ₄ ), sodium hydroxide (NaOH), dolomite (a mixture of Dolomite, MgCO and CaCO) and mixtures thereof It is characterized by the addition of. The pH adjusting agent is preferably added until the pH 5.0 to 8.0 conditions at the time of anaerobic digestion.

The pH adjusting agent not only adjusts the pH during fermentation, but also concentrates the organic acid in the form of a salt when the organic acid is concentrated through distillation.

In the present invention, the organic acid concentrated to 30% or more is separated by each organic acid by azeotropic distillation with desalination, or concentrated to 70% or more of the organic acid salt in the form of salt, and the organic acid is separated from the salt by adding an acid. After distillation or azeotropic distillation can be separated into each organic acid component.

As the pH adjusting agent, when ammonium carbonate ((NH ₄ ) ₂ CO ₃ ) or ammonium bicarbonate (NH ₄ HCO ₃ ) is used, the organic acid and ammonium chloride produced in organic acid fermentation are separated by heating and then combined with CO ₂ . It can be recycled and used. In addition, the dolomite, sodium carbonate (Na ₂ CO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ) is blown with CO ₂ to the organic acid produced in the calcium carbonate (CaCO ₃ ) and organic acid fermentation, and then separated from the organic acid and salt and continuously Organic acids can be separated by extraction with an extraction solvent, and likewise can be easily recovered by recycling CO ₂ discharged during fermentation.

If when using NaOH and concentrated by distilling the medium containing the produced organic acid sodium salt, and sulfuric acid (H ₂ SO ₄₎ the organic acid is free, and sodium sulfate (Na ₂ SO ₄₎ the are produced, generating sodium sulfate (Na ₂ SO ₄ ) is electrolyzed and can be re-divided into NaOH and H ₂ SO ₄ so that it can be easily recycled. It is economically preferable to use a bipolar membrane for the electrolysis of Na ₂ SO ₄ .

In addition, although NaOH is a somewhat energy-intensive process, the addition of HCl to the resulting organic acid yields organic acids and NaCl, and the electrolysis of NaCl produces NaOH, H ₂ and Cl ₂ , and H ₂ and Cl ₂ It can be combined again to produce HCl and reused.

The salt in the form of ammonia can be mixed with HCl to form NH ₄ Cl to liberate the organic acid and then distillate to separate the organic acid. MgCl ₂ can be formed by adding a salt such as Mg (OH) ₂ to the remaining NH ₄ Cl, and NH ₄ OH can be recovered by distillation. MgCl ₂ is recovered as HCl and Mg (OH) ₂ by hydrolytic thermal decomposition. Can be reused, and each can be reused.

In general, a culture solution containing a low concentration (about 3%) of an organic acid cannot be recovered by evaporation of the organic acid together with water during distillation. Therefore, it is desirable to concentrate the produced organic acid to 30% or more.

Therefore, in the present invention, the concentration of the organic acid to 30% or more is characterized in that water is removed from the fermentation broth or the organic acid is selectively extracted from the fermentation broth.

Removing water from the fermentation broth is carried out by distillation, which is a multi-effect distillation (MED), multiple stage flash distillation (MSF), steam compression distillation (MVC) Compression distillation) can be used.

The present invention may also perform reverse osmosis (RO) or forward osmosis (FO) to increase energy efficiency, and then remove water from the fermentation broth by distillation. When the reverse osmosis method or the forward osmosis method is used, the organic acid is to be further concentrated from the fermentation broth, and about 3% of the organic acid may be concentrated to 6 to 10% in the fermentation broth.

Figure 3 is an explanatory diagram showing a concentration process by the forward osmosis method of the water-soluble fermentation product according to an embodiment of the present invention.

As shown in FIG. 3, in the case of forward osmosis, a membrane composed of the prepared osmotic pressure can be used to increase the osmotic pressure up to 249.5 atm using a high salt concentration on the permeate side (draw side), and the osmotic pressure when the concentration of the brine at the feed side is 2M. Since this is 113.8 atm, the osmotic pressure difference (Δπ) between the feed side and the permeate side (draw side) can be 124.9 atm (US 7,303,674; McCutcheon et al., J. Membr. Sci . 278: 114-123, 2006 This is much higher than the osmotic pressure difference (50 atm) of the conventional reverse osmosis method.

Therefore, rather than removing water from the fermentation broth using only distillation, it is preferable from the viewpoint of energy efficiency when water is removed by forward osmosis or reverse osmosis first and then distillation is used.

Since the organic acid is present in a non-ionized form at a pH lower than the pKa value, the extraction solvent may be added to the culture solution to extract the organic acid, and then back extracted again to selectively extract the organic acid. The degree of extraction may vary depending on the degree of lipophilicity of the organic acid, the degree of ionization (pH), the temperature, the presence of salts, the degree of other impurities, and the like. Generally, butyric acid in organic acids is easier to extract than acetic acid, and can be extracted at a somewhat higher pH (5.0 to 6.0).

4 is an explanatory diagram showing an organic acid extraction and back extraction process using an extraction solvent according to an embodiment of the present invention.

As shown in Figure 4, when the fermentation broth containing 3% of VFA is injected into the liquid-liquid extraction tower, the VFA is extracted by mixing with the extraction solvent. The extraction solvent is an organic phase and has a specific gravity smaller than that of water and is discharged from the top of the tower after phase separation. After the VFA is extracted, the fermentation broth is discharged from the bottom of the extraction tower, can be refluxed into the fermentation tank and reused in the fermentation process.

The organic phase containing the extracted VFA is injected into a liquid-liquid extraction tower for back extraction of the VFA. In the high pH state, VFA is extracted back from the organic phase of the extractant into the water phase, and the basic solution (NaOH or ammonia) is continuously added to the water phase refluxed to the reverse extraction tower to maintain the pH at 10.0 or 80 If hot water is applied, the VFA can be extracted back into the water phase. As the water introduced into the concentration tank, water refluxed from the distillation column may be used.

The extraction solvent is (a) dioctylamine (DOA), trioctylamine (TOA), triaurylamine, Di-tridecylamine, Alamine 336, Aliquat 336 (main component: methyltrioctylammonium chloride), trioctylphosphine oxide (TOPO), tributylphosphate (TBP) and mixtures thereof (B) Methyl isobutyl ketone (MIBK), chloroform, octanol, dodecanol, n-alkanes (C ₆ ~ C ₃₀ ), xylene, oleyl alcohol, kerosene, and mixtures thereof. The mixed liquid of the diluent selected can be illustrated.

The extractant is preferably used with a diluent for extraction efficiency and ease of processing. The diluent serves to enhance the extraction efficiency by controlling the high viscosity and specific gravity of the extraction solvent, the surface tension between the organic phase and the water phase.

The extractant and diluent may be selected in the range of 1: 0 to 1:20, but is preferably mixed in a ratio of 1: 1 to 1: 4, and the extraction solvent is in the range of 1 to 100 parts by weight based on 100 parts by weight of the fermentation broth. Although it may be used, it is usually preferable to apply in the range of 50 to 100 parts by weight.

In the present invention, the concentrated organic acid 30% or more can be separated and purified into each organic acid through fractional distillation.

Organic acids are hydrophilic in nature and are difficult to separate from water. This is because when the water evaporates, the organic acid is also evaporated together so that the organic acid is not concentrated and vaporizes together. Therefore, in the present invention, the organic acid is concentrated to a high concentration of 30% or more, and then, an additive such as ethyl acetate, iso-butyl acetate, n-butyl acetate, and the like is subjected to azeotropic distillation to separate and purify the organic acid.

EXAMPLE

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example 1 Production of Organic Acid by Multistage Continuous Fermentation

The food waste was ground finely with a mixer, and the organic acid fermentation was performed using a portion having a relatively small solid content through a sieve having a diameter of 0.5 mm. Food waste contained about 50% of starch. The bioreactor uses a four-stage bioreactor configured as shown in FIG. 5, and each stage is equipped with a sponge-type filter to increase cell concentration and prevent leakage of undecomposed food waste. Initially, the internal oxygen was removed by injecting nitrogen gas, and afterwards, the internal gas including carbon dioxide and hydrogen generated during organic acid production was recycled by using a compressor to minimize the inflow of external air and to agitate the culture solution. Add 25% NaHCO ₃ to the dry weight of food waste and adjust the pH to 8.0. Inoculate 10% (v / v) of anaerobic digestion fluid (KAIST food waste treatment system anaerobic digester), It kept above 6.5. At this time, the food waste was intermittently added to each stage, the total dilution rate was maintained at 0.2 / day, the fermentation temperature was maintained at about 40 ℃.

Figure 6 is a graph showing the concentration of the organic acid over time in the four-stage bioreactor.

As shown in Figure 6, the total organic acid concentration was 34.6 g / L in four stages, the productivity was 6.92 g / L / day, the yield was very high, 0.49 g / g food waste. At this time, the composition of organic acid: acetic acid: propionic acid: butyric acid ratio of 5: 1: 5 was found to be relatively high content of butyric acid.

Example 2: Prevention of Lactic Acid Production

The food waste was ground finely with a mixer, and the organic acid fermentation was performed using a portion having a relatively small solid content through a sieve having a diameter of 0.5 mm. 50 g / L of food waste on a dry weight basis was placed in an anaerobic flask, 5 g / L yeast extract and a buffering agent (additive) of Table 1 were added, and the anaerobic digestion liquid was added to 10% of the final volume. After that, shaking culture was performed at 42 ° C. and 120 rpm.

Table 1

Option	Na-O	Na-X	NH 4 -O	NH 4 -X	Ca-O	Ca-X
Buffering agent (g / L)	NaHCO 3 , 30 g / L	NaHCO 3 , 30 g / L	(NH 4 ) 2 CO 3 , 15 g / L	(NH 4 ) 2 CO 3 , 15 g / L	CaCO 3 , 30 g / L	CaCO 3 , 30 g / L
Initial pH	8.0	7.5	8.0	9.0	8.0	7.0
Food waste (dry g / L)	50	50	50	50	50	50

Final pH at 6 days of fermentation, lactate, butyrate, TVFA (total organic acid except lactate) and the like, and the results are shown in Table 2.

TABLE 2

Option	Na-O	Na-X	NH 4 -O	NH 4 -X	Ca-O	Ca-X
Initial pH	8.0	7.5	8.0	9.0	8.0	7.0
Final pH	7.89	7.95	7.23	7.00	5.37	5.16
Total product (g / L)	29.36	29.14	27.94	25.27	32.41	29.68
TVFA (g / L)	24.26	23.80	19.77	18.54	4.79	2.88
Lactate (% of product)	0.0	0.0	0.0	4.0	79	86
Butyrate (% of product)	17.6	12.8	21.2	42.9	0.0	0.0

TVFA: total volatile fatty acids except lactate

As shown in Table 2, about 80% or more of lactic acid was produced in the experimental group using CaCO ₃ , whereas little lactic acid was generated in the experimental group using NaHCO ₃ or (NH ₄ ) ₂ CO ₃ . In the experimental group with little or no lactic acid production, the pH did not drop below 7.0 during incubation. In particular, when NaHCO ₃ was added, the pH was maintained above 7.5, and no lactic acid was produced on the 6th day of fermentation. It was estimated that even if some lactic acid is initially produced, the pH is disadvantageous to the growth conditions of the lactic acid bacteria and the lactic acid is converted back to the organic acid.

Example 3. Confirmation of rejection of organic acid using reverse osmosis

The organic acid was concentrated using a reverse osmosis filter module composed of a polypropylene reverse osmosis membrane (Filmtech, USA). The organic acid used in the experiment was used as ammonium acetate containing ammonium salt, pH was adjusted with ammonia water. Concentration was carried out by varying the volume of the acetate solution to 2L, 1.6L, 1.2L, 0.8L, respectively, and the concentration of the concentrated acetate solution was confirmed the pH, effluent volume and flow rate, and the results are shown in Table 3. . The experiment was repeated three times.

TABLE 3

	Acetate solution volume (L)	Acetate conc. (G / L)	Acetate Solution pH	Effluent volume (L)	Effluent Flow Rate (L / min)	Rejection ratio (%)	Remarks
Experiment 1	2	1.41	6.3	0	-	-	start
	1.6	1.68	6.27	0.4	0.04	78.20
	1.2	2.11	6.33	0.8	0.06	77.00
	0.8	3.00	6.37	1.2	0.05	75.61
Experiment 2	2	1.38	9.02	0	-	-	start
	1.6	1.50	8.93	0.4	0.10	97.17
	1.2	1.92	8.92	0.8	0.09	96.03
	0.8	2.76	8.79	1.2	0.08	95.77
Experiment 3	2	1.33	10.85	0	-	-	start
	1.6	1.51	10.77	0.4	0.10	97.07
	1.2	1.91	10.78	0.8	0.09	96.74
	0.8	2.74	10.67	1.2	0.07	96.55

As shown in Table 3, water was removed from the acetic acid solution using a reverse osmosis process to increase the acetic acid concentration on the residue. At each pH the concentration of acetic acid could be more than doubled from 1.33-1.41 to 2.74-3.00. In addition, when the pH of the introduced acetic acid solution was increased from 6.3 to 10.85, the rejection ratio of acetic acid to the reverse osmosis membrane was also maintained from 78% to more than 96%.

Example 4 Acetic Acid Rejection Verification Using Osmotic Pressure

Acetic acid was concentrated using a flat plate system equipped with a polypropylene osmotic membrane (Filmtech, USA). 3.1 g / L acetic acid solution was added to the feed side, and 30% NaCl solution was used for the draw side. The pH of the acetic acid solution in the feed side was maintained at 6.4, which is close to the general fermentation conditions, and the pH was used as ammonia water. The concentration and volume of acetic acid at the beginning and end of the feed side and draw side were measured, and the results are shown in Table 4.

Table 4

	acetic acid (g / L)	liquid volume (mL)
Feed side (initial)	3.1	300
Feed side (final)	3.6	220
Draw side (initial)	0	300
Draw side (final)	0.4	380

As shown in Table 4, the acetic acid could be concentrated to 3.6 g / L by removing 80 mL of water from the initial 3.1 g / L acetic acid solution. The rejection ratio of acetic acid on the osmotic membrane was 88.9%. The water removed from the feed side was 26.7% of the total amount, resulting in an acetic acid concentration of 116.1%.

Example 5 Concentration of Organic Acid Salts by Distillation

While maintaining a distillation temperature at 110 ~ 120 ℃ using a rotary evaporator, sodium acetate in a salt form containing sodium was concentrated. The initial solution volume was 300 mL, and the concentration of the organic acid solution was 26.3 g / L based on acetic acid. The distillation amount according to the distillation time, the acetic acid concentration of the distillate, and the acetic acid concentration of the residue were shown in Table 5.

Table 5

Distillation time (min)	Distillation amount (mL)	Acetate concentration in distillate (g / L)	Acetate concentration in residue (g / L)
60	20	0.138	28.2
132	60	0.016	32.9
163	105	0.013	40.5
180	145	0.001	50.9
270	265	0.016	225.6
288	275	0.023	315.8

As shown in Table 5, the acetic acid concentration of the distilled solution was maintained below 0.1 g / L it was confirmed that most of the acetic acid remains as a residue can be concentrated in acetic acid. Final acetic acid concentration in the residue was determined to be 315.8 g / L.

Example 6 Concentration Method by Solvent Extraction and Back Extraction of VFA

6-1: Organic Acid Extraction Using Extraction Solvent

A simulated fermentation broth (acetic acid: propionic acid: butyric acid = 6: 3: 4) was prepared using experimental grade pure VFAs, 4 mL of the organic phase was mixed with 4 ml of water (water phase) in a flask, followed by stirring for several seconds, Separation was carried out for 3 minutes at 7000 rpm using a centrifuge, and the results are shown in Table 6. Octanol (diluent) containing 25% of Alamine 336 (extractant) was used as the organic phase.

Table 6

VFA concentration applied (g / L)	Water phase (g / L)	Organic phase (g / L)	Distribution coefficient (organic phase / water phase)
4.7	0.22	4.46	20
9.6	0.59	8.98	15.3
29.0	2.48	26.5	10.7
56.0	8.30	47.7	5.8

As shown in Table 6, as the initial VFA concentration increased, the partition coefficient tended to gradually decrease, but the extraction coefficient proceeded well with a partition coefficient of 5.8 even at a VFA concentration of 56 g / L. In particular, at 29 g / L expected to be the VFA concentration of the fermentation broth, the partition coefficient was measured to be about 10.7, and it was confirmed that more than 90% of the VFA in the water phase was extracted into the organic phase.

6-2: Extraction of VFA with Various Diluents

As shown in Table 7, VFA was extracted under the same conditions as 6-1 while controlling the concentration of the extractant (Alamine 336) to 0 to 100% using various diluents (octanol, octane, MIBK and kerosene).

TABLE 7

Thinner Type	Extractant Concentration	Water	Organic phase	Distribution coefficient
Octanol
		0	7.83	6.45	0.82
		10	2.59	11.68	4.51
		25	1.15	13.13	11.47
		40	1.20	13.08	10.92
		50	1.34	12.94	9.67
		75	2.70	11.58	4.29
100		7.30	11.58	4.29
octane	0	13.69	0.59	0.04
	10	11.66	2.62	0.22
	25	10.07	4.21	0.42
	40	9.06	5.21	0.58
	50	8.54	5.73	0.67
	75	8.16	6.12	0.75
	100	7.30	6.98	0.96
MIBK	0	7.27	7.01	0.96
	10	5.39	8.89	1.65
	25	4.50	9.78	2.17
	40	4.50	9.77	2.17
	50	4.80	9.48	1.98
	75	5.71	8.56	1.50
	100	7.30	6.98	0.96
Kerosine	0	14.18	0.10	0.01
	10	11.63	2.65	0.23
	25	9.95	4.33	0.43
	40	8.97	5.31	0.59
	50	8.45	5.83	0.69
	75	7.63	6.65	0.87
	100	7.30	6.98	0.96

As shown in Table 7, when octanol and MIBK were used as diluents, a partition coefficient of 1.5 or more was obtained in all sections of the extractant concentration, and the highest partition coefficient was obtained in a 25% extractant solution using octanol as a diluent ( 11.47) can be obtained. On the other hand, when octane and kerosene were used as diluents, relatively low extraction efficiency with a partition coefficient of 1 or less was observed regardless of the concentration of the extractant.

6-3: Back Extraction of Extracted Organic Acids

In order to extract VFA back to the water phase from the organic phase (VFA concentration: 26.8%) containing VFA extracted in 6-1, the pH of distilled water was increased to 10 or more using NaOH aqueous solution. The organic phase and the water phase were mixed at a ratio of 1: 1 to extract VFA, and the water phase was recovered again. The recovered water phase was lowered again due to the extraction of VFA, so the pH was adjusted to 10 or more using an aqueous NaOH solution. The pH-adjusted water phase and the organic phase including VFA were mixed again in the same manner as described above, and the VFA was concentrated by repeating the method of recovering the water phase.

As a result, as shown in Figure 7, in a total of six concentrations VFA was continuously concentrated in water, it can be seen that more than 300 g / L concentration.

Example 7 Recovering VFA by Component Using Distillation

The simulation program Hysys was designed to separate and recover the mixture of VFA and water from the extraction process for each component. As shown in FIG. 8, the VFA solution (acetic acid: propionic acid: butyric acid = 6: 3: 4) concentrated at 300 g / L or more through extraction and back extraction using an amine solvent as distillation 1-4. After distillation in the named distillation column, the components were separated. At this time, the temperature of the distillation 1 is 99 ~ 100 ℃, the temperature of the distillation 2 is 99 ~ 100 ℃, the temperature of the distillation 3 is 117 ~ 118 ℃, the temperature of the distillation 4 was maintained at 140 ~ 141 ℃.

In the first 'distillation 1', water and acetic acid were discharged to the top of the tower and residual acetic acid, propionic acid and butyric acid were discharged to the bottom of the tower.

Since the relative volatility of each component is similar in the distillation of water and VFA occurring in 'distillation 1', it is not easy to separate by general distillation, so that iso-butyl acetate is added as an additive for azeotropic distillation. Added at ˜39%. The additive forms a three-phase system with water-VFA, and VFA moves to the bottom of the tower, and water and additives move to the top. Since the water and the additives do not mix and the phases separate, the additives continue to reflux and remain in the column and the water is discharged to the top. Other residues such as salts and proteins in the fermentation broth were discharged from the distillation1 to the bottom of the tower.

In 'distillation 2', water and acetic acid discharged to the top of 'distillation 1' are separated for each component, and the water discharged to the top of the tower is refluxed for the extraction process.

The VFA solution consisting only of acetic acid, propionic acid and butyric acid discharged to the bottom of 'distillation 1' was injected into 'distillation 3', the remaining acetic acid was recovered to the top, and the mixture of propionic acid and butyric acid to the bottom Was discharged.

Finally, in 'Distillation 4', a mixture of propionic acid and butyric acid discharged to the bottom of 'distillation 3' is separated and recovered for each component, and the recovery yield of each component is maintained at 95% or more.

As a result, the method of separating volatile organic acids according to the present invention not only dramatically increases the economics of the anaerobic digestion process, but also enables high value-adding through the synthesis of various compounds derived from organic acids, and is particularly economical when converting organic acids to biofuels. Economical production of liquid fuel for transportation can be improved.

As described above in detail the specific parts of the present invention, it is apparent to those skilled in the art that such specific description is merely a preferred embodiment, thereby not limiting the scope of the present invention. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

The method of producing organic acids from the biomass according to the present invention enables not only to efficiently produce organic acids from terrestrial, aquatic, marine or biodegradable organic mixed biomass, and to economically concentrate the produced organic acids, Since fractional distillation can separate the organic acid of the desired composition, it is possible to increase the added value of the organic acid can significantly increase the economics of the organic acid bioprocess.

Claims (10)

1. Process for producing organic acid from biomass comprising the following steps:

   (a) fermenting the biomass to produce organic acids;

   (b) concentrating the produced organic acid to at least 30%; And

   (c) recovering the organic acid by fractional distillation of the concentrated organic acid.
2. The method of claim 1 wherein the biomass is selected from the group consisting of plant biomass, animal biomass, municipal waste biomass, and mixtures thereof.
3. The method of claim 1, wherein step (a) comprises anaerobic digestion of the biomass in a multistage bioreactor comprising a cell recirculation apparatus.
4. According to claim 1, wherein the step (a) is calcium carbonate (CaCO ₃ ), ammonium bicarbonate (NH ₄ HCO ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), sodium carbonate (Na ₂ CO ₃ ), hydrogen carbonate A pH adjuster selected from the group consisting of sodium (NaHCO ₃ ), sodium sulfate (Na ₂ SO ₄ ), sodium hydroxide (NaOH), dolomite and mixtures thereof is added and fermented at pH 5.0-8.0. How to.
5. The method of claim 1, wherein concentrating the organic acid to at least 30% comprises removing water from the fermentation broth or selectively extracting the organic acid from the fermentation broth.
6. 6. The method of claim 5, wherein removing water from the fermentation broth is performed by distillation.
7. The method of claim 6, wherein the distillation method is selected from the group consisting of Multi-Effect Distillation (MED), Multiple Stage Flash distillation (MSF), and Mechanical Vapor Compression distillation (MVC). Characterized in that the method.
8. The method of claim 5, wherein the removing of water from the fermentation broth is carried out by reverse osmosis (RO) or forward osmosis (FO), followed by distillation.
9. The method of claim 5, wherein the selective extraction of the organic acid comprises (a) dioctylamine (DOA), trioctylamine (TOA), triaurylamine, Di-tridecylamine, Alamine 336, Aliquat 336, trioctylphosphine oxide (TOPO), tributylphosphate (TBP) and Extractants selected from the group consisting of mixtures thereof and (b) diluents selected from the group consisting of Methyl isobutyl ketone (MIBK), chloroform, octanol, dodecanol, n-alkanes, xylene, oleyl alcohol, kerosene and mixtures thereof The mixed solution is added to or in contact with the culture medium to extract the organic acid, and then the method is characterized in that the back extraction.
10. The method of claim 1, wherein the fractional distillation is performed by azeotropic distillation after adding an additive selected from the group consisting of ethyl acetate, iso-butyl acetate, n-butyl acetate, and mixtures thereof to the concentrated organic acid. Way.

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