KR20140058988A - Novel method for recovery of xylose from byproducts generated in biomass-pretreatment processes and use thereof - Google Patents

Abstract

The present invention relates to a method for collecting xylose from a biomass-pretreated byproduct and a method for using same. More specifically, the present invention relates to a method for collecting monomer-type xylose through the acid hydrolysis of xylan that is a main ingredient of hemicelluloses included in waste water which is pretreatment byproduct that occurs in a biomass acid/alkali chemical pretreatment step and to a method for producing ethanol or xylitol by fermenting the collected xylose. In the present invention, the xylose ingredient is separated from acid-/alkali-treated waste liquid that is generated in a process of producing bio-energy and bio-refinery using a biomass so that sugars can be provided in order for the re-production of bio-refinery products such as ethanol or xylitol. Moreover, the method of the present invention re-uses the acid-/alkali-treated byproduct and acid-/alkali-treated solution so that the cost consumed to treat waste is reduced and environmental charges can be reduced. High-price sugar alcohol that is derived from xylose is produced so that the unit cost for producing biomass-derived ethanol and bio-refinery chemical products can be reduced.

Description

Description: TECHNICAL FIELD The present invention relates to a method for recovering xylose from a biomass pretreatment by-product and a method for recovering xylose from the biomass pretreatment by-

The present invention relates to recovery of xylose from biomass pretreatment byproducts and a method for using the same, and more particularly, to a method for recovering hemicellulose from hemicellulose, which is a pretreatment by-product produced in a chemical pretreatment step such as acid / alkali of biomass, (Xylan), which is a main component of xylan, is recovered as a monomeric form of xylose by acid hydrolysis, and a method for producing ethanol or xylitol by fermenting the recovered xylose.

Generally, the biomass of herbaceous biomass and woody biomass contains 30-40% cellulose per 100 g dry weight, 20-25% hemicellulose, and 25-30% lithogreen. Therefore, in the process for the production of ethanol and biorefinery products, in the process of enzymatic saccharification fermentation using cellulase and yeast or bacteria, the physicochemical, physical and chemical properties of cellulose and hemicellulose, which are strongly bound to lignin, And a process of relaxing the biomass tissue through a biological pretreatment process (Mosier et al . , Bioresour . Technol ., 96: 673, 2005; Agbor et al. , Biotechnol . Adv ., 29: 675, 2011). The pretreatment process not only increases the content of cellulose per unit dry weight through removal of hemicellulose and lignin among the three components constituting the biomass, but also relaxes the tissue of the biomass and the cellulosic polymer, It facilitates the accessibility of cellulase enzymes and facilitates the conversion of cellulose to glucose (Mosier et al . , Bioresour. Technol ., 96: 673, 2005).

Various physical and chemical methods are used depending on the characteristics of biomass (Agbor et al . , Biotechnol . Adv ., 29: 675, 2011). In general, chemical methods are known to exert hemicellulose for acid treatment and lignin removal for alkaline treatment (Mosier et al. , Bioresour. Technol., 96: 673, 2005; Agbor et al. , Biotechnol. Adv ., 29: 675, 2011). This pretreatment process is an essential process for the efficient saccharification of biomass, and the content of sugar converted from biomass in the enzymatic saccharification process is determined by appropriate pretreatment with individual biomass (Mosier et al . , Bioresour . Technol ., 96: 673, 2005; Yang and Wyman, Biofuels, Bioprod , Bioref ., 2:26, 2008; Kumar et al . , Ind . Eng . Chem . DOI: 10.1021 / ie801542g, 2009).

In the chemical pre-treatment process, acids such as sulfuric acid, hydrochloric acid, and phosphoric acid are used as acid pretreatment process. However, the removal efficiency of hemicellulose in the treatment of 4% (w / v) sulfuric acid in herbaceous and woody biomass (Kumar et < RTI ID = 0.0 > al . , Ind. Eng . Chem . DOI: 10.1021 / ie801542g, 2009). In the chemical pretreatment process, solid phase, which is a biomass with increased cellulose content, and liquid phase waste water containing hemicellulose and lignin, respectively, are mass-produced. In acid pretreatment, the liquid phase contains an excessive amount of xylenes, a polymeric form of xylose, or xylose, in monomeric form, which is the main component of hemicellulose, and in the case of alkaline pretreatment, some of the hemicellulose is in complex form with lignin It is known to be eluted in the pretreatment waste liquid (Kumar et al . , Ind . Eng . Chem . DOI: 10.1021 / ie801542g, 2009; Carvalheiro et al . , J. Sci . Ind . Res ., 67: 849, 2008). The wastewater generated in the chemical pretreatment process using acid and alkali is composed of lignin-based polymer containing the xylose pentose sugar liberated from the biomass and various aromatic compounds, Oxygen Demand), TOC (Total Organic Carbon), as well as acidic or alkaline wastewater containing solid components.

Alternative methods such as the treatment of wastewater through anaerobic digestion and the conversion of biogas through digestion of sludge generated during wastewater treatment have been conducted as a method for treating high concentration wastewater generated in the biomass pretreatment process (Yang and Wyman, Biofuels , Bioprod , Bioref ., 2:26, 2008). Bioethanol production using lignocelluloses biomass and pre-treatment in biorefinery process and wastewater treatment in process account for about 20% of the production cost of the product (Hinman et al. al . , Appl . Biochem . Biotechnol., 34/35: 639, 1992; Humbird et al . , NREL Technical Report NREL / TP-5100-47764, 2011). Therefore, pretreatment process and reduction of wastewater treatment cost play a decisive role in reducing the production cost of biomass-derived fuel and chemical precursor.

The present inventors' patent relating to the present invention has been disclosed in Korean Patent Application No. 10-2011-0119175 entitled " Method for producing palm fruit husk fiber-derived biomass having increased cellulose content through sequential acid / base pretreatment " Patent Publication No. 10-2008-0094647 "Method for manufacturing activated carbon from by-product of tropical fruit biomass", and Patent document 10-2010-0118865 "Method for producing environmentally friendly biotan using biomass byproduct" The domestic patent for the fraction of xylose component is disclosed in Korean Patent Application No. 10-2007-0072682 entitled " Method for producing xylitol using hydrolyzed glycosylated liquid containing xylose and arabinose from tropical fruit biomass byproduct & 2004-0018323 " Method for recovery of xylose ", Application No. 10-2009-0060397 " Method for fractionating lignocellulosic biomass and fractionating device " As an international patent, US patent application No. 12 / 648,483 (Pub. No. US2010 / 0167351) "Integrated methods for processing palm fruit bunches", US patent no. 6,086,681 " method for recovery of xylose from solutions ". However, there has been no report on the recovery of xylose from biomass pretreatment by-products.

As a result of intensive efforts to recover xylose from biomass pretreatment by-products, the present inventors have found that the main component of hemicellulose contained in wastewater, which is a pretreatment by-product generated in a chemical pretreatment step such as acid / alkali of biomass, (Xylan) was recovered as a monomeric form of xylose through acid hydrolysis, and it was confirmed that ethanol and xylitol were produced, thereby completing the present invention.

It is an object of the present invention to provide a method for separating xylose from biomass acid pretreatment by-products or alkali pretreatment by-products and a method for using the same.

In order to achieve the above object, the present invention provides a method for producing biomass comprising: (a) treating biomass with acid to separate biomass and acid treatment waste; (b) washing the separated biomass with water, and then separating the washed biomass and the washing liquid; (c) reusing the acid-treated waste liquid separated in the step (a) and the washing liquid separated in the step (b) to recover the acid-treated waste liquid and the washing liquid containing xylose; (d) treating the waste solution and washing solution containing xylose with calcium ions to precipitate and remove the acid contained in the waste solution and the washing solution in a calcium salt form; And (e) removing the fermentation inhibitor contained in the acid-removed waste solution and the washing solution of step (d) using activated charcoal, and recovering an aqueous solution containing the xylose component The present invention provides a method for separating xylose from a waste fluid generated in a water bath.

The present invention also provides a method for producing ethanol, comprising the steps of: (a) culturing a yeast resistant to an acid treatment solution of biomass using an aqueous solution containing xylose separated by the above method to produce ethanol; And (b) recovering the produced ethanol.

The present invention also provides a method for producing xylitol, comprising: (a) culturing a yeast having resistance to an acid treatment solution using an aqueous solution containing xylose separated by the above method to produce xylitol; And (b) recovering the produced xylitol.

The present invention also provides a method for producing biomass, comprising the steps of: (a) treating biomass with a basic material, subjecting the biomass to alkali treatment, and then separating the biomass and alkali treatment waste; (b) concentrating the lignin and hemicellulose contained in the alkaline treatment waste liquid by using a separation-filtration membrane after removing the large particles in the separated alkali treatment waste liquid; (c) treating the concentrate containing lignin and hemicellulose with an acid in step (b) to liberate xylose through acid hydrolysis of the xylan in the lignin-hemicellulose complex; (d) treating the aqueous solution free of xylose with calcium ion to precipitate an acid component contained in the waste solution by a calcium salt; And (e) removing the fermentation inhibitor contained in the aqueous solution from which the acid component has been removed in step (d) using activated charcoal, and recovering an aqueous solution containing the xylose component The present invention provides a method for separating xylose from a waste fluid generated in a water bath.

The present invention also provides a method for producing xylitol, comprising: (a) culturing a yeast having resistance to an acid treatment solution using an aqueous solution containing xylose separated by the above method to produce xylitol; And (b) recovering the produced xylitol.

In the present invention, it is possible to provide a sugar for the reproduction of bio-refineries such as ethanol or xylitol by separating the xylose component in the acid / alkali treatment waste liquid generated in the bio-energy production process and the bioraphinera production process using the biomass. In addition, the method of the present invention can reduce the environmental burden ratio by reducing waste water treatment cost or waste treatment cost through reuse of acid / alkali treatment by-products and acid / alkali treatment solution, and it is possible to reduce the environmental burden ratio of expensive xylose- Alcohol production can reduce the cost of producing biomass-derived ethanol and bio-refinery chemicals.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a whole process through an acid treatment for removal of hemicellulose component of palm fruit husk biomass, and a process for separating xylose from a waste liquid discharged from the process.
FIG. 2 is a graph showing the change in the amount of xylose released according to the acid concentration to be treated with the palm fruit husk biomass (A) and the result (B) of the sugar component analysis in the acid treatment solution using HPLC.
FIG. 3 is a graph showing the concentration (A) of xylose in the acid-waste liquid and the washing water of the biomass according to the number of times of continuous reuse of the waste water treated with the biomass of palm kernel and the concentration of the acid hydrolyzate as a fermentation inhibiting substance And the change (B).
FIG. 4 is a graph showing the cell growth pattern (A) following continuous-batch cultivation of yeast candida tropicallis resistant to an acid-treated xylose solution without removing the fermentation inhibiting substance, and the use of xylose (O) (B).
FIG. 5 is a graph showing the cell growth pattern (A) and the use of xylose (○) and production (FIG. 5) according to the continuous-batch culture of yeast Pichia styptis having resistance to an acid-treated xylose solution without removing the fermentation inhibitor And the amount of ethanol (?) (B).
6 is a graph showing changes in the concentrations of xylose () and glucose () and the changes in the concentrations of ethanol () and acetic acid () in the acid-treated xylose solution in which the fermentation inhibitor was not removed, ) Production.
7 is data showing the change in the concentration of xylose () and the amount of xylitol () produced when resistant yeast Candida tropicallis was cultured in an acid-treated xylose solution without removing fermentation inhibiting substances.
FIG. 8 is a schematic view showing a whole process through alkaline-heat treatment for removing lignin / hemicellulose component from a large-sized crude biomass, and a process for separating xylose from a waste liquid discharged from the process.
9 is a graph showing changes in the concentration of xylose in acid hydrolysis (A) according to the concentration of sulfuric acid in the alkaline waste solution and the HPLC chromatograms of the sugar components in the alkaline waste solution before and after acid- B).
10 is data showing the change in the concentration of xylose () and the amount of xylitol () produced when the resistant yeast Candida tropicallis was cultured in the alkali-treated xylose solution without removing the fermentation inhibiting substance.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

In one aspect, the present invention provides a method for treating biomass comprising: (a) treating biomass with acid to separate biomass and acid treatment waste; (b) washing the separated biomass with water, and then separating the washed biomass and the washing liquid; (c) reusing the acid-treated waste liquid separated in the step (a) and the washing liquid separated in the step (b) to recover the acid-treated waste liquid and the washing liquid containing xylose; (d) treating the waste solution and washing solution containing xylose with calcium ions to precipitate and remove the acid contained in the waste solution and the washing solution in a calcium salt form; And (e) removing the fermentation inhibitor contained in the acid-removed waste solution and the washing solution of step (d) using activated charcoal, and recovering an aqueous solution containing the xylose component To a method for separating xylose from a waste liquid generated in the process.

In the present invention, the biomass used in the acid treatment may be a palm kernel, but is not limited thereto.

In the present invention, the acid to be treated in step (a) may be characterized by being a strong acid such as sulfuric acid, hydrochloric acid, phosphoric acid, or a weak acid. However, it is not limited thereto, and step (a) (v / v) of sulfuric acid, and reacting at 100 to 200 ° C.

In one embodiment of the present invention, the process of separating xylose from the waste liquid was carried out by subjecting the palm fruit husk to an acid treatment. The acid-heat treatment was carried out at 0.1 to 8.0% (v / v) of sulfuric acid in dried biomass (150 g) of palm fruit husk at 121 ° C for 1 hour and then the hemicellulose component was removed through acid treatment (A) containing the biomass and the hemicellulose component of the biomass were separated. The pretreated biomass was immersed in water at room temperature to remove the denatured material from the surface, and then the biomass was recovered from the washing solution (B). To the same amount of biomass (150 g) Under the same conditions. Thereafter, the biomass was recovered, and the biomass was washed using the washing solution (B), which was repeated 5 times or more.

As a result of measurement of the xylose concentration in the acid-treated wastewater and the by-products in the wastewater according to the concentration of sulfuric acid used in the acid treatment of the present invention, the higher the concentration of sulfuric acid used in the acid treatment, the more the xylose content in the wastewater 2A). As a result of analyzing the sugar components in the waste solution, it was found that 82% of xylose, 4% of glucose, 3% of oligo-xylose and 3% of acetic acid (Fig. 2B).

The acid solution discharged from the acid treatment process using palm fruit husk contains excessive amount of xylose. Through continuous recycling of the waste liquid generated in the acid treatment process, it is possible to reduce the sulfuric acid solution used in the acid treatment, It is possible to prepare a solution containing xylose of xylose.

Since acid hydrolysis is automatically carried out by acid treatment of xylan in hemicellulose, it is not necessary to further carry out an acid hydrolysis reaction for recovering the polymeric form of xylan into monomeric xylose, It has the advantage of being able to fractionate Ross. In addition, in order to remove sugar components and acid hydrolysis products from the acid-treated biomass surface, a weak acid solution of the washing water discharged through the pulping operation in which acid-treated biomass is immersed in water contains a considerable amount of xylose, It is possible to obtain a high concentration of xylose fraction product from the palm fruit husk by mixing with the previously acid treated waste liquid.

In the present invention, the calcium ion in the step (d) may be added in the form of a calcium salt such as calcium carbonate or calcium hydroxide, but the present invention is not limited thereto. The step (d) The calcium hydroxide may be added such that the pH of the waste solution and the washing solution is 5 to 8, and the reaction is carried out at 20 to 30 ° C.

In the present invention, the fermentation inhibiting substance of step (e) may be an acid-modified strain sugar component containing furfural.

In another embodiment of the present invention, in order to remove sulfuric acid (H ₂ SO ₄ ) on the aqueous solution of the acid treatment solution (acid treatment waste solution + wash solution) (pH <1) (CaCO ₃ ) or calcium hydroxide (Ca (OH) ₂ ) which is capable of converting sodium hydroxide (Na ₂ SO ₄ ) into salt can be slowly injected to a pH of 5 to 8, The neutralization process was carried out in a weakly alkaline state. In this case, since the sugar components in the solution may be denatured by an exothermic reaction, the solution is maintained at 20 to 30 ° C or less through a cooling device. The amount of calcium carbonate in the solid state or the amount of calcium hydroxide is determined by the volume of the acid- And it is variable depending on the degree of.

The calcium sulfate (CaSO ₄ ) salt precipitated on the aqueous solution was removed by gravity sedimentation, filtering and centrifugation. After removal of the calcium sulfate salt, the concentration of the collected xylose and other components in the liquid phase was measured by HPLC As a result of the analysis, xylose was measured to contain 64.3 ± 8.8 g / l, glucose 7.6 ± 2.4 g / l, acetate 10.1 ± 1.4 g / l and furifurate 0.7 ± 0.2 g / l.

An aqueous solution containing excess amount of xylose from which the calcium sulfate salt has been removed can be converted into an acid treated strain sugar component such as furifural which acts as a fermentation inhibiting substance through activated carbon treatment or through an activated carbon column, , And an aqueous solution containing decolorized pale yellow xylose was recovered through the above procedure and finally an aqueous sugar solution containing xylose was obtained from an acid treatment waste solution in an efficiency of 80% or more .

According to another aspect of the present invention, there is provided a method for producing a biomass acid-treated wastewater comprising the steps of: (a) culturing yeast resistant to biomass acid-treated waste liquid using an aqueous solution containing xylose separated by the method described above to produce ethanol; And (b) recovering the produced ethanol.

In the present invention, step (a) may be characterized in that the culture is carried out at a temperature of 20 ° C to 30 ° C and a pH of 5 to 8 and 200 rpm.

In the present invention, the yeast is a Candida tropicallis ( Candida) adapted to be resistant to the biomass acid treatment solution tropicalis ) CBS94 or Pichia stipitis CBS5773 strain, but the present invention is not limited thereto.

In the present invention, Candida tropicallis tropicalis ) CBS94 and Pichia stipitis CBS5773 strains were used to adapt to the acid treatment solution of biomass to have tolerance. Both of these strains are known as strains capable of growing using xylose as a carbon source.

In another embodiment of the present invention, an experiment was conducted to select resistant yeast strains capable of converting xylose in acid-treated wastewater containing an fermentation inhibiting substance into ethanol or xylitol, and Xylose And Yeast nitrogen base (YNB) were inoculated into the liquid medium and the batch batch culture was repeated 10 times. As a result of culturing the cells at a constant time during each batch culture and examining the changes of the components in the culture medium, it was found that the growth of Candida tropicallis CBS94 strain, which was adapted to the xylose solution containing the fermentation inhibitor, (Fig. 4A) and changes in the content of the culture medium (Fig. 4B) showed that the cell growth rate was faster and the utilization rate of xylose was increased more than two times as the number of continuous batch cultivation was increased. In addition, it was confirmed that xylitol was not produced in the first culture, but xylitol was produced in the second batch culture and the xylitol production ability was improved 5 times or more after 10 consecutive cultures.

Further, Pichia styptis CBS5773, which was adapted to the xylose solution containing the fermentation inhibiting substance through the 10 times continuous-batch culturing, examined the strain growth degree (Fig. 5A) and the ingredient content change in the culture medium (Fig. 5B) , The cell growth rate was faster and the utilization rate of xylose was increased more than twice as compared with the initial culture.

In the present invention, the yeast having resistance to the acid treatment waste solution may be characterized in that the yeast is cultured by a continuous batch method in a medium containing an acid treatment waste liquid separated by the above method.

In another embodiment of the present invention, the ethanol fermentation was carried out using yeast P. stipitis with increased tolerance to the acid treatment waste solution, and as a result, the relatively high concentration of Pichia staphytis Rapid consumption of glucose (4 g / ℓ) present in a small amount in the culture medium, ethanol production at a rate of 71.9 g / ℓ of xylose was observed to be slow, and 6.7 g / ℓ of ethanol was produced in about 140 hours 6). At this time, the finally remaining xylose was confirmed to be 53.5 g / l, and acetic acid was kept constant at less than 10 g / l.

According to another aspect of the present invention, there is provided a method for producing xylitol, comprising: (a) culturing yeast resistant to a biomass acid-treated waste liquid using an aqueous solution containing xylose separated by the method described above to produce xylitol; And (b) recovering the produced xylitol.

In the present invention, step (a) may be characterized in that the culture is carried out at a temperature of 20 ° C to 30 ° C and a pH of 5 to 8 and 200 rpm.

In the present invention, the yeast resistant to the acid treatment wastewater is treated with biomass acid treatment Candida tropicillis ( Candida tropicalis ) CBS94 or Pichia stipitis CBS5773 strain, but the present invention is not limited thereto.

In the present invention, the yeast having resistance to the acid treatment waste solution may be characterized in that the yeast is cultured by a continuous batch method in a medium containing an acid treatment waste liquid separated by the above method.

As a result of carrying out the xylitol fermentation using yeast Candida tropicallis ( C. tropicalis ) with increased tolerance to the acid treatment waste solution, candida tropicallis was found to have a high consumption rate of xylose at the initial stage of culture It was confirmed that the production of xylitol was rapidly carried out while consuming 74 g / l xylose rapidly after 10 hours of culture, and it was confirmed that xylitol was produced at a maximum of 25.2 g / l in 61 hours of culture (Fig. 7 ).

According to another aspect of the present invention, there is provided a method for producing biomass, comprising the steps of: (a) treating biomass with a basic material, subjecting the biomass to an alkali treatment process, and then separating the biomass and the alkali- (b) concentrating the lignin and hemicellulose contained in the alkaline treatment waste liquid by using a separation-filtration membrane after removing the large particles in the separated alkali treatment waste liquid; (c) treating the concentrate containing lignin and hemicellulose with an acid in step (b) to liberate xylose through acid hydrolysis of the xylan in the lignin-hemicellulose complex; (d) treating the aqueous solution free of xylose with calcium ion to precipitate an acid contained in the waste solution with a calcium salt to remove the acid; And (e) removing the fermentation inhibitor contained in the acid-free aqueous solution of step (d) using activated carbon, and recovering an aqueous solution containing the xylose component. The present invention relates to a method for separating xylose from a waste solution.

In the present invention, the biomass is a large aquifer ( Miscanthus gianteus ), but the present invention is not limited thereto.

The herbaceous biomass, Miscanthus gianteus ) is composed of 38.7% cellulose by dry weight, 13.2% hemicellulose, 24.3% lignin, 1.4% ash and other ingredients including moisture.

In the present invention, the basic substance in step (a) may be a strong basic substance or a weak basic substance such as calcium hydroxide, potassium hydroxide, magnesium hydroxide, sodium hydroxide and sodium bicarbonate, but is not limited thereto , And the step (a) of the present invention may be characterized in that the reaction is carried out at 50 to 120 ° C by treating 0.1 to 5.0 M sodium hydroxide (NaOH).

In the present invention, the alkaline treatment waste solution filtered in the step (b) may be reused in the alkali treatment process of the step (a).

In the present invention, the step (b) may be performed by removing large particles in alkaline wastewater by centrifugal separation, sedimentation by gravity, or a sand column, but the present invention is not limited thereto.

In another embodiment of the present invention, the giant aqueduct is decomposed to a size of 3 mm or less using a continuous pretreatment apparatus, treated with 0.4 to 1.2 M sodium hydroxide (NaOH) To carry out an alkali treatment step. Alkali treatment wastewater containing lignin / hemicellulose and lignin / hemicellulose was separated through an alkali treatment step. The recovered biomass was treated with water to remove alkaline components remaining on the surface, For 24 hours, and then the components of the biomass were analyzed. As a result of the analysis, the alkaline treated macroscopic organisms were composed of 64.1% of cellulose per dry weight, 10.9% of hemicellulose, 0.5% of lignin, and other ingredients including moisture, and the alkali treatment partially removed lignin / hemicellulose Respectively.

In the present invention, the separation-filtration membrane in step (b) may be microfiltration (MF), ultrafiltration (UF) or nanofiltration (NF). However, no.

In order to recover and reuse the alkaline waste liquid containing the lignin / hemicellulose component that is leaked in the alkali treatment process of the present invention, the waste liquid is subjected to centrifugal separation, gravity precipitation, or a sand column, Is melted in alkaline wastewater using a nanofiltration (NF) containing microfiltration (MF), ultrafiltration (UF) or strong alkali resistant polysulfone reinforcing support The lignin / hemicellulose was concentrated, and the alkaline waste solution to be filtered was reused.

In the present invention, the acid in step (c) may be characterized by being a strong acid such as sulfuric acid, hydrochloric acid, phosphoric acid, and a weak acid. However, the acid is not limited thereto. In step (c) / v) sulfuric acid, and the reaction is carried out at 100 to 200 ° C for 10 minutes to 120 minutes.

Unlike the acid treatment, the alkali-treated wastewater is present as hemicellulose in the form of xylan, which is free from the xylose component in the pretreatment, and is in complex with lignin. Therefore, xylose is separated from the lignin / hemicellulose in the alkali wastewater A hydrolysis process through an acid treatment is required. The concentration of xylose liberated from the alkaline waste solution is determined by the concentration of the sulfuric acid to be injected and can be liberated by hydrolysis in the acidic state after the alkali solution is neutralized by the sulfuric acid solution.

In the present invention, hydrolysis was carried out through an acid treatment in order to liberate xylose in an alkaline waste liquid containing lignin / hemicellulose recovered by using a nanofiltration membrane (NF), and xylose Were analyzed. As a result, xylose was not liberated when the concentration of sulfuric acid was 0 to 6% (v / v), and 8 to 14% (v / v) after 6% (v / v) ), It was confirmed that xylose was liberated from xylan of hemicellulose (Fig. 9A). The maximum amount of xylose was recovered when 10% (v / v) sulfuric acid was added (FIG. 9B), and when the concentration of sulfuric acid was 10% (v / v) or more, the content of xylose decreased Respectively. It can be seen that the xylose content was decreased because the xylose component was denatured by acid-thermal hydrolysis.

In addition, when xylose was liberated from the alkaline concentrate recovered using the microfiltration membrane (MF) and the ultrafiltration membrane (UF), xylose was not liberated when treated with 2% (v / v) sulfuric acid, When xylose was liberated by treating 6% (v / v) sulfuric acid with the alkaline concentrate recovered using the filtration membrane (MF), 20.4 g / l of xylose was liberated and recovered using an ultrafiltration membrane (UF) When the alkali concentrate was treated with 6% (v / v) sulfuric acid to liberate xylose, 42.4 g / l of xylose was liberated. When xylose was liberated by treatment with 6% (v / v) sulfuric acid, it was confirmed that the content of purifuric, an inhibitory substance of fermentation, was small.

In the present invention, the calcium ion in the step (d) may be added in the form of a calcium salt such as calcium carbonate or calcium hydroxide, but the present invention is not limited thereto. The step (d) The calcium hydroxide is added such that the pH of the waste solution is 5 to 8, and the reaction is carried out at 20 to 30 ° C.

In the present invention, the fermentation inhibiting substance in step (e) may be an acid-modified strain sugar component containing furfural.

The method of the present invention may further comprise the step of separating and purifying the ionic material contained in the acid-removed aqueous solution by using an ion exchange resin in the step (e).

Among the ionic substances, the cation may be removed using a cation exchange resin resin or column of AG 50W-X8, and the anion may be removed using an anion exchange resin resin or column of AG1-X8. But is not limited thereto.

In the present invention, in order to remove the sulfuric acid (H ₂ SO ₄ ) on the aqueous solution of the acid-hydrolysis reaction liquid of the alkaline treatment waste liquid, a solid carbonic acid capable of converting sulfuric acid (H ₂ SO ₄ ) Calcium carbonate (CaCO ₃ ) or calcium hydroxide (Ca (OH) ₂ ) was slowly poured into the solution to a pH of 5 to 8 to neutralize the solution in weak acid or weak alkali. Since the sugar components in the solution may be denatured by an exothermic reaction, the solution is maintained at 20 to 30 ° C or less through a cooling device. The amount of calcium carbonate in the solid state or the amount of calcium hydroxide It is variable depending on the degree of pH.

In the present invention, the calcium sulfate (CaSO ₄ ) salt precipitated on the aqueous solution is removed by precipitation by gravity, filtering or centrifugation, and an aqueous solution containing excess xylose from which the calcium sulfate salt has been removed is treated with activated carbon Or purified fructose, which acts as a fermentation inhibitor, through the passage of an activated carbon column, and a dark brown component due to a change in sugar content in the solution.

In addition, the sodium ion (Na) in the aqueous solution was removed by cation exchange resin column of AG 50W-X8 resin, and anion present in trace amount was removed by AG1-X8 anion exchange resin column. Through the above procedure, an aqueous solution containing decolorized pale yellow xylose was recovered, and an aqueous sugar solution containing xylose was finally obtained from the alkali treatment waste solution at an efficiency of 80% or more.

According to another aspect of the present invention, there is provided a method for producing xylitol, comprising: (a) culturing a yeast resistant to an acid hydrolyzate of an alkali treatment solution using an aqueous solution containing xylose separated by the above method to produce xylitol; And (b) recovering the produced xylitol.

In the present invention, step (a) may be characterized in that the culture is carried out at a temperature of 20 ° C to 30 ° C and a pH of 5 to 8 and 200 rpm.

In the present invention, the yeast is a Candida tropicallis ( Candida) adapted to have tolerance to an acid hydrolyzate of an alkali treatment solution tropicalis ) CBS94 or Pichia stipitis CBS5773 strain, but the present invention is not limited thereto.

In the present invention, the yeast having resistance to the solution in which xylose is liberated through acid hydrolysis in the alkali treatment solution can be obtained by culturing the yeast in a continuous batch method in a medium containing an excessive amount of xylose obtained by the above method And then separated.

In another embodiment of the present invention, xylitol fermentation was performed using yeast Candida tropicallis ( C. tropicalis ) with increased resistance to the above-mentioned solution. As a result, Candida tropicallis showed a slow consumption rate of xylose at the initial stage of culture From 20 hours after the incubation, it was confirmed that xylitol production was accelerated while 30 g / l xylose was rapidly consumed, and it was confirmed that xylitol was produced at a maximum of 11.5 g / l in 54 hours of culture (FIG. 10).

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

Acid treatment of palm kernel and reuse of acid treatment solution

The present invention reuses the acid treatment solution to increase the pretreatment efficiency of the biomass and to increase the amount of xylose in monomer form of xylan, which is a component of hemicellulose, in the waste liquid generated in the acid treatment step. Detailed reaction conditions and overall process are shown in Fig.

In the present invention, the process of separating xylose from the waste liquid was carried out by treating the palm fruit husk with an acid. The acid treatment was conducted at 121 ° C for 1 hour using 0.1 to 8.0% (v / v) of dilute sulfuric acid in dried biomass (150 g) of palm fruit husk, and then the hemicellulose component was removed through acid treatment (A) containing the biomass and the hemicellulose component of the biomass were separated. After the acid-treated biomass was immersed in water at room temperature, the fibrous tissue of the palm kernel was loosened by pulping to remove the denatured material from the surface, and the biomass was removed from the washing liquid (B) The same amount of biomass (150 g) was recovered and reacted under the same conditions using the acid treatment waste solution (A) used above. Thereafter, the biomass was recovered and the biomass was washed using the washing solution (B). The content of xylose in the acid-waste liquid (A) and the washing water (B) discharged in the acid treatment process and the by-products produced in the biomass acid treatment process were monitored while repeating the above-mentioned process five times or more.

 Performance analysis was performed using high-performance liquid chromatography (HPLC) to measure the changes in xylose concentration in acid-treated wastewater and the by-products in the waste solution according to the concentration of sulfuric acid used in the acid treatment.

The HPLC system (Young-Lin instrument, Anyang, Korea) equipped with a refractive index detector (Waters, Milford, Mass., USA) and an auto- sampler was used. The analytical column was Rezex ROA-Organic Acid H + ; Phenomenex, Torrance, CA, USA ) and a guard cartridge (KJ0-4282; Phenomenex, Torrance , SecurityGard that contains CA, USA) ^TM Using a guard column, the column temperature was maintained at 65 占 폚 and the mobile phase was measured with a 2.5 mM sulfuric acid solution at a flow rate of 0.6 ml / min.

As a result, the content of xylose in the waste solution increased as the concentration of sulfuric acid used in the acid treatment increased (Fig. 2A). As a result of analyzing the sugar content in the waste solution, xylose 82%, glucose 4% , Oligo-xylose 3% and 3% acetic acid 3% were measured (FIG. 2B).

As a result of measuring the change in xylose concentration in the acid-treated waste solution to be reused, it was 20.3 ± 3.6 g / ℓ in one use, 39.9 ± 11.1 g / ℓ in two use, 55.1 ± 20.0 g / ℓ in three use, 70.2 ± 29.0 g / L, and 82.3 + 38.8 g / L of xylose when used five times (FIG. 3A). Glucose, acetic acid and furfural, which are organic acids measured by acid hydrolysis products, were detected and it was confirmed that the concentration contained in the waste solution increased with the frequency of recycling of the acid treatment waste solution (Fig. 3B).

Acid treatment From the waste liquid  Fermentation inhibition Removed toxic substances Xylose  Preparation of solution

In order to remove sulfuric acid (H ₂ SO ₄ ) on the aqueous solution of the acid treatment solution (acid treatment waste solution + wash solution) (pH <1) reused more than 5 times in Example 1, sulfuric acid (H ₂ SO ₄ ) salt of calcium carbonate (CaCO ₃ ) or calcium hydroxide (Ca (OH) ₂ ), which can be converted into a salt, is slowly injected to a pH of 5 to 8 to neutralize the solution in a weakly acidic or weakly alkaline state Respectively. Because the exothermic reaction may cause denaturation of the saccharide components in the solution, the solution is kept at 20 to 30 ° C or less through a cooling device, and the process of precipitating the insoluble salt is as follows:

_{H 2 SO 4 (aq) +} CaCO 3 (s) → CaSO 4 (s) + 2H 2 O (l) + CO 2 (g) , or

H ₂ SO ₄ ( aq ) + Ca (OH) ₂ ( s )? CaSO ₄ ( s ) + 2H ₂ O ( l )

In this process, the calcium sulfate (CaSO ₄ ) salt precipitated on the aqueous solution was removed by gravity sedimentation, filtering and centrifugation. After removing the calcium sulfate salt, the concentration of the collected xylose and other components As a result of HPLC analysis, xylose was measured to contain 64.3 ± 8.8 g / l, glucose 7.6 ± 2.4 g / l, acetate 10.1 ± 1.4 g / l and furifurate 0.7 ± 0.2 g / l.

An aqueous solution containing excess amount of xylose from which the calcium sulfate salt has been removed can be converted into an acid treated strain sugar component such as furifural which acts as a fermentation inhibiting substance through activated carbon treatment or through an activated carbon column, , And an aqueous solution containing decolorized pale yellow xylose was recovered through the above procedure and finally an aqueous sugar solution containing xylose was obtained from an acid treatment waste solution in an efficiency of 80% or more .

In the acid treatment liquid containing the fermentation inhibiting substance Xylose  Development of resistant yeast for use

Since the sugar solution containing the xylose component recovered in Example 2 still contains the fermentation inhibiting substance, the resistant yeast strain capable of converting the xylose in the acid treatment solution containing the fermentation inhibiting substance into ethanol or xylitol The experiment was performed to select the sample.

In the present invention, Candida tropicallis tropicalis ) CBS94 or Pichia stipitis CBS5773 strains were used. These two strains are known to be able to grow using xylose as a carbon source.

The strain was plated on solid medium of YPD (10 g / l Yeast extract; 20 g / l Bacto-peptone; 20 g / l Dextrose) and cultured at 25-30 ° C. A single colony was selected. Thereafter, the selected colonies were inoculated into a liquid medium containing 10 ml of the acid treatment solution (25 g / l xylose content) and 6.7 g / l yeast nitrogen base (YNB) containing the fermentation inhibitor, Batch culture was performed at 30 ° C with stirring at 240 rpm for 24 hours. After cultivation, 10% (v / v) of the culture solution was added to 10 ml of the acid treatment solution (25 g / l xylose content) containing the fermentation inhibitor and 6.7 g / l yeast nitrogen base (YNB) The culture was inoculated in the same manner as described above, and the above-mentioned continuous batch culture was repeated 10 times.

The culture was taken at the same time during each batch culture to examine cell growth and changes in the culture medium. Cell growth was monitored at a wavelength of 600 nm using a spectrophotometer and converted to the cell dry weight. Changes in the components in the culture medium were also analyzed by HPLC analysis.

(FIG. 4A) and changes in the content of the culture medium (FIG. 4B), which were adapted to the xylose solution containing the fermentation inhibitor, through batch culture for 10 consecutive times, The cell growth rate was faster and the utilization rate of xylose increased more than twice as compared with the initial culture as the number of times of recovery increased. In addition, it was confirmed that xylitol was not produced in the first culture, but xylitol was produced in the second batch culture and the xylitol production ability was improved 5 times or more after 10 consecutive cultures.

The Pichia styptis CBS5773 adapted to the xylose solution containing the fermentation inhibiting substance through the 10th continuous-batch culturing was examined for the degree of growth of the strain (Fig. 5A) and the content of the ingredient in the culture medium (Fig. 5B) The cell growth rate was faster than that of the culture and the utilization rate of xylose increased more than two times.

Ethanol fermentation with yeast resistant to acid treatment solution

The yeast P. Stipitis with increased tolerance to the acid treatment solution in Example 3 was subjected to seed culture at 30 ° C for 24 hours using a YPD liquid medium, and then pre-cultured The strain was inoculated 10% (v / v) in 15 ml of xylose solution containing 1% YNB (acid treatment solution containing fermentation inhibitor) and stirred at 30 ° C and 240 rpm for 24 hours. The cultured cells were recovered by centrifugation, and then 1 liter of the same medium was added to a 1.5 L bioreactor and inoculated with a high concentration of cells (8 OD _{600 nm} ). At this time, the operation conditions of the bioreactor were maintained at 30 ° C, pH 5.5 to 6.0 and 200 rpm, and the changes of xylose and glucose concentration and ethanol and acetic acid production according to cell growth were analyzed by HPLC analysis.

As a result of the ethanol fermentation, it was confirmed that the pycyastifitis inoculated at a relatively high concentration rapidly consumed glucose (4 g / ℓ) present in a small amount in the culture medium and ethanol production was slowly consumed at 71.9 g / ℓ of xylose , And 6.7 g / l of ethanol was produced in about 140 hours (Fig. 6). At this time, the finally remaining xylose was confirmed to be 53.5 g / l, and acetic acid was kept constant at less than 10 g / L.

 Using yeast resistant to acid treatment solution Xylitol  production

The yeast Candida tropicallis ( C. tropicalis ) having increased tolerance to the acid treatment solution in Example 3 was added to 15 ml of xylose solution containing 1% YNB (acid treatment solution containing the fermentation inhibitor) at 10% (v / v) and the mixture was stirred at 30 DEG C and 240 rpm for 24 hours. The cultured cells were recovered by centrifugation, and then 1 liter of the same medium was added to a 1.5 L bioreactor and inoculated with a high concentration of cells (8 OD _{600 nm} ). At this time, the operating conditions of the bioreactor were maintained at 30 ° C, pH 5.5 to 6.0 and 200 rpm, and the concentration of xylose and xylitol production were analyzed by HPLC analysis.

As a result of xylitol fermentation, Candida tropicallis showed a slow consumption rate of xylose at the initial stage of culture, but from 10 hours after cultivation, it was confirmed that xylitol was rapidly consumed at 74 g / It was confirmed that xylitol up to 25.2 g / l was produced (Fig. 7).

Large italic alkali In the treatment liquid  For the reuse of alkali treatment liquid Membrane (filter membrane)  Used Hemicellulose  And lignin removal

The present invention reuses the alkali treatment solution to increase the alkali treatment efficiency of the biomass and increase the lignin / hemicellulose in the waste solution generated in the alkali treatment step. The detailed reaction conditions and the overall process are shown in FIG.

In the present invention, Giant Miscanthus (Miscanthus gianteus ) was subjected to alkali treatment to separate lignin / hemicellulose from the waste solution. The giant aqueducts were decomposed to a size of 3 mm or less using a continuous pretreatment apparatus, treated with 0.4 to 1.2 M sodium hydroxide (NaOH), and reacted at 70 to 90 ° C to carry out an alkali treatment step. Alkali treatment wastewater containing lignin / hemicellulose and lignin / hemicellulose was separated through an alkali treatment step. The recovered biomass was treated with water to remove alkaline components remaining on the surface, For 24 hours, and then the components of the biomass were analyzed. As a result of the analysis, the alkali treated giant aphids consisted of 64.1% of cellulose per dry weight, 10.9% of hemicellulose, 0.5% of lignin, and other ingredients including water and alkali treatment to remove most of the lignin / hemicellulose Respectively.

In order to recover and reuse the alkaline waste solution containing the lignin / hemicellulose component that is leaked out in the alkali treatment process of the present invention, the waste solution may be centrifuged, precipitated by gravity or sand column, The particles are removed and the lignin / hemicellulose melted in the alkaline treatment wastewater is concentrated using microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF), and the alkaline waste solution Was reused.

The removal efficiency of the turbidity was improved by removing the lignin and hemicellulose components present in the waste solution. The filtrate and the concentrate remaining after filtration showed that the removal rate of the non-decomposed material was almost 100% (Table 1).

Analysis of Properties of Biomass Alkali Treatment Waste Liquor Treated with Nano Membrane (NF) Sample Volume Reduction (%) Turbidity
(NTU) TOC
(mg / L) Na ⁺
(mg / L) Alkaline wastewater stock solution - 2,800 5,575 5,331 Pretreatment liquid - 1,500 5,101 5,206 Double concentrate 50 3,065 7,858 5,336 Filtrate 50 0.01 2,381 5,059 4 times concentrated liquid 75 4,785 9,417 5,031 Filtrate 75 0.01 3,288 4,399 8 times concentrated liquid 90 7,445 11,996 5,201 Filtrate 90 0.01 2,890 5,012 Membrane first filtrate - 0.01 2,243 4,703 After washing the membrane, - 0.01 5,887 5,585

As a result of analyzing the total organic carbon (TOC) in the waste liquid, the organic carbon removal efficiencies of concentrate and filtrate were 3.3 times, 2.8 times, and 4.2 times as high as 2 times, 4 times, and 8 times, respectively, Sodium ion (Na ⁺ ), an indicator of the concentration of sodium hydroxide used as an alkali, was maintained at a concentration difference of about 20% between the maximum and minimum concentrations before and after filtration.

Concentration removed from alkaline processing solution By hemicellulose from Xylose  collection

7-1: Glass of xylose using acid hydrolysis process

In the present invention, in Example 6, hydrolysis was carried out through an acid treatment solution to liberate xylose in an alkaline waste liquid containing lignin / hemicellulose recovered using a nanofiltration membrane (NF), and the concentration of sulfuric acid added We analyzed the liberation of xylose according to the ratio.

First, a stock solution of sulfuric acid was added to a concentrated macroreticular alkali-treated wastewater at a ratio of 0 to 14% (v / v), and then heat-treated at 121 ° C for 1 hour to form a hemi The xylose component of cellulose was hydrolyzed with xylose, and the free amount of xylose according to the ratio of each sulfuric acid concentration after the reaction was analyzed by HPLC.

As a result of the analysis, xylose was not liberated when the concentration of sulfuric acid was 0 to 6% (v / v), and 8 to 14% (v / v) after 6% (v / v) ), It was confirmed that xylose was liberated from xylan of hemicellulose (Fig. 9A). The maximum amount of xylose was recovered when 10% (v / v) sulfuric acid was added (FIG. 9B), and when the concentration of sulfuric acid was 10% (v / v) or more, the content of xylose decreased Respectively. It can be seen that the xylose content was decreased because the xylose component was denatured by acid-thermal hydrolysis.

In Example 6, xylose was recovered by using the above method in an alkali concentrate recovered using a microfiltration membrane (MF) and an ultrafiltration membrane (UF), and the amount of xylose and acid hydrolysis products produced was measured (Table 2).

The amount of xylose and acid hydrolyzate obtained by acid hydrolysis of the alkali concentrate recovered through the filtration membrane sample glucose
(g / l) Xylose
(g / l) Acetic acid
(g / l) Furigural
(g / l) Alkaline wastewater stock solution 2% (v / v) sulfuric acid treatment - - - - 6% (v / v) sulfuric acid treatment 3.5 25.8 5.8 0.9 10% (v / v) sulfuric acid treatment 4.7 20.0 7.0 3.4 Pretreatment liquid 2% (v / v) sulfuric acid treatment - - 6.5 - 6% (v / v) sulfuric acid treatment 1.7 23.7 5.6 0.7 10% (v / v) sulfuric acid treatment 1.6 16.1 5.1 1.5 MF Filtrate concentrate 2% (v / v) sulfuric acid treatment - - 6.3 - 6% (v / v) sulfuric acid treatment 1.8 20.4 5.7 0.7 10% (v / v) sulfuric acid treatment 1.4 13.9 5.1 1.7 UF Filtrate concentrate 2% (v / v) sulfuric acid treatment - - 4.1 - 6% (v / v) sulfuric acid treatment 2.6 42.4 4.8 1.6 10% (v / v) sulfuric acid treatment 2.3 28.8 4.0 4.1

As a result of freeing the xylose from the alkaline concentrate recovered by using the microfiltration membrane (MF) or the ultrafiltration membrane (UF), the xylose was not liberated when treated with 2% (v / v) sulfuric acid and the microfiltration membrane MF) was used to liberate xylose by treatment with 6% (v / v) sulfuric acid to recover the alkali concentrate, 20.4 g / l of xylose was liberated and the alkali concentrate (UF) recovered using an ultrafiltration membrane Was treated with 6% (v / v) sulfuric acid to liberate xylose, 42.4 g / l of xylose was liberated.

In addition, when xylose was liberated by treatment with 6% (v / v) sulfuric acid, it was confirmed that the content of purifuric which is an inhibitory substance of fermentation was small.

7-2: Free Xylose  collection

The recovery of the acid hydrolyzed xylose component in Example 7-1 was carried out in the same manner as in Example 2.

In order to remove sulfuric acid (H ₂ SO ₄ ) on the aqueous solution of acid-hydrolysis reaction liquid, solid calcium carbonate (CaCO ₃ ) which can convert sulfuric acid (H ₂ SO ₄ ) Or calcium hydroxide (Ca (OH) ₂ ) was slowly poured into the solution to a pH of 5 to 8 to neutralize the solution in a weakly acidic or weakly alkaline state. Since the exothermic reaction may cause denaturation of the saccharide components in the solution, the solution is maintained at a temperature of 20 to 30 ° C or less through a cooling device. The amount of calcium carbonate in the solid state or the amount of calcium hydroxide is determined by the volume of the acid- And the process of precipitation into an insoluble salt is represented by the following formula:

_{H 2 SO 4 (aq) +} CaCO 3 (s) + NaOH (aq) → CaSO 4 (s) + 2H 2 O (l) + CO 2 (g) + NaOH (aq) or

_{H 2 SO 4 (aq) +} Ca (OH) 2 (s) + NaOH (aq) → CaSO 4 (s) + 2H 2 O (l) + NaOH (aq)

In this process, the calcium sulfate (CaSO ₄ ) salt precipitated in the aqueous solution was removed by gravity sedimentation, filtering and centrifugation, and the aqueous solution containing excess xylose from which the calcium sulfate salt was removed was treated with activated carbon Through the passage through the activated carbon column, acid - treated strain sugar components such as furifurals acting as fermentation inhibitors were removed and components showing dark brown due to the change of sugar content in the solution were removed.

In addition, sodium (Na) ions present in the aqueous solution were removed with a cation exchange resin column such as AG 50W-X8 resin, and anions present in trace amounts were removed with an anion exchange resin column such as AG1-X8. Through the above procedure, an aqueous solution containing decolorized pale yellow xylose was recovered, and an aqueous sugar solution containing xylose was finally obtained from the alkali treatment waste solution at an efficiency of 80% or more.

 Using yeast resistant to acid treatment solution Xylitol  production

The yeast Candida tropicallis ( C. tropicalis ) with increased tolerance to the acid treatment solution in Example 3 was added to 3 ml of xylose solution containing 1% YNB (fermentation inhibition isolated from the alkaline treated waste solution recovered in Example 7 (V / v), and the mixture was stirred at 30 DEG C and 240 rpm for 24 hours. The culture of the cultured cells was inoculated into 15 ml of xylose solution containing 1% YNB (xylose solution containing fermentation inhibitor) at 10% (v / v) and stirred at 30 ° C and 240 rpm for 24 hours The consumption and production of xylose and xylitol were analyzed by HPLC analysis.

As a result of xylitol fermentation, Candida tropicallis showed a slow consumption rate of xylose at the initial stage of cultivation, but from 20 hours after cultivation, it was confirmed that xylitol production was occurred while consuming 30 g / l xylose rapidly, It was confirmed that 11.5 g / l of xylitol was produced (Fig. 10).

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (21)

A method for separating xylose from a waste liquid generated in a biomass acid treatment process comprising the steps of:
(a) treating the biomass with acid to separate the biomass and acid treatment waste;
(b) washing the separated biomass with water, and then separating the washed biomass and the washing liquid;
(c) reusing the acid-treated waste liquid separated in the step (a) and the washing liquid separated in the step (b) to recover the acid-treated waste liquid and the washing liquid containing xylose;
(d) treating the waste solution and washing solution containing xylose with calcium ions to precipitate and remove the acid contained in the waste solution and the washing solution in a calcium salt form; And
(e) removing the fermentation inhibitor contained in the acid-removed waste solution and the washing solution of step (d) using activated carbon, and recovering an aqueous solution containing the xylose component.
The method of separating xylose according to claim 1, wherein the biomass is palm kernel.
2. The method of separating xylose according to claim 1, wherein the acid treatment in step (a) is performed by treating sulfuric acid at 0.1 to 8.0% (v / v) at 100 to 200 ° C.
The method according to claim 1, wherein calcium carbonate or calcium hydroxide is added to the calcium ion of step (d) so that the pH of the waste solution and the washing solution is 5 to 8, and the reaction is carried out at 20 to 30 ° C. How to separate.
The method of separating xylose according to claim 1, wherein the fermentation inhibiting substance of step (e) is an acid-modified strained sugar component containing furfural.
A process for the production of ethanol comprising the steps of:
(a) culturing yeast resistant to the biomass acid treatment solution using an aqueous solution containing xylose separated by the method according to any one of claims 1 to 5 to produce ethanol; And
(b) recovering the produced ethanol.
The yeast according to claim 6, wherein the yeast is Candida tropicallis ( Candida tropicalis ) CBS94 or Pichia stipitis CBS5773. &lt; / RTI &gt;
A method for producing xylitol comprising the steps of:
(a) culturing yeast resistant to the biomass acid treatment solution using an aqueous solution containing xylose isolated by the method of any one of claims 1 to 5 to produce xylitol; And
(b) recovering the produced xylitol.
9. The method according to claim 8, wherein the yeast is Candida tropicallis ( Candida tropicalis ) CBS94 or Pichia stipitis CBS5773. &lt; / RTI &gt;
A method for separating xylose from waste water generated in a biomass alkali treatment process comprising the steps of:
(a) treating the biomass with a basic material, subjecting the biomass to an alkali treatment process, and then separating the biomass and the alkali treatment waste;
(b) concentrating the lignin and hemicellulose contained in the alkaline treatment waste liquid by using a separation-filtration membrane after removing the large particles in the separated alkali treatment waste liquid;
(c) treating the concentrate containing lignin and hemicellulose with an acid in step (b) to liberate xylose through acid hydrolysis of the xylan in the lignin-hemicellulose complex;
(d) treating the aqueous solution free of xylose with calcium ion to precipitate an acid contained in the waste solution with a calcium salt to remove the acid; And
(e) removing the fermentation inhibitor contained in the acid-free aqueous solution of step (d) using activated carbon, and recovering an aqueous solution containing the xylose component.
11. The method of claim 10, wherein the biomass is selected from the group consisting of Miscanthus gianteus ). &lt; / RTI &gt;
The method of separating xylose according to claim 10, wherein the basic substance of step (a) is treated with sodium hydroxide (NaOH) of 0.1 to 5.0 M and reacted at 50 to 180 ° C.
11. The method of separating xylose according to claim 10, wherein the alkaline treatment waste solution filtered in step (b) is reused in the alkali treatment step (a).
[10] The method of separating xylose as set forth in claim 10, wherein the step (b) removes large particles in the alkaline wastewater by centrifugal separation, sedimentation by gravity, or a sand column.
The method of separating xylose according to claim 10, wherein the separation-filtration membrane in step (b) is a microfiltration (MF), ultrafiltration (UF) or nanofiltration (NF) .
[Claim 11] The method according to claim 10, wherein the acid hydrolysis in step (c) is performed by treating sulfuric acid at 2 to 20% (v / v) and performing acid treatment at 100 to 200 DEG C for 10 to 120 minutes To isolate xylose.
11. The method according to claim 10, wherein calcium carbonate or calcium hydroxide is added to calcium ion of step (d) so that the pH of the waste liquid is 5 to 8, and the reaction is carried out at 20 to 30 ° C or less. Way.
11. The method of separating xylose according to claim 10, wherein the fermentation inhibiting substance in step (e) is an acid-modified strained sugar component containing furfural.
The method of claim 10, wherein the step (e) further comprises the step of separating and purifying the ionic material contained in the aqueous solution from which the acid component has been removed by using an ion exchange resin. / RTI &gt;
A method for producing xylitol comprising the steps of:
(a) culturing a yeast resistant to an acid hydrolyzate of an alkali treatment solution by using an aqueous solution containing xylose separated by the method of any one of claims 10 to 19 to produce xylitol; And
(b) recovering the produced xylitol.
21. The method according to claim 20, wherein the yeast is selected from the group consisting of Candida tropicallis tropicalis ) CBS94 or Pichia stipitis CBS5773. &lt; / RTI &gt;

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