Method for processing vegetable biomass

Abstract

The present invention relates to an energy-efficient process for the treatment of plant biomass, particularly sugar cane, for the production of carbohydrates and ethanol, using physico-chemical and extraction techniques, as well as very simple milling configurations, thereby minimizing energy consumption during extraction of the cane juice. The biomass treated and obtained through this process, when subjected to a fermentation process for the production of ethanol, increases the yield of the process in comparison with that of traditional sugar cane. It can also be used for the production of enzymes, animal feedstuffs, and other useful products.

Claims

1. A process for the treatment of sugar cane biomass, consisting of the stages of: a) defibrating the sugar cane biomass; b) milling the defibrated sugar cane biomass, the milling stage characterized by at most 3 three-roller milling combinations, resulting in a saccharose content primary juice, and a bagasse containing a residual amount of saccharose and a fibrous fraction; c) separating the saccharose content primary juice of stage b) from the bagasse of stage b); and then d) submitting the bagasse obtained in stage c) to a one-step physico-chemical treatment with addition of at least one chemical agent at conditions with severity level (S) within the range from 3.70 to 4.50 wherein the at least one chemical agent added is selected from the group consisting of ammonia, ammonium hydroxide, water steam, water, and combinations thereof.

2. The process according to claim 1, wherein the defibrating stage includes the placement of the sugar cane biomass in a piece of equipment selected from the group consisting of a blade mill and a knife mill.

3. The process according to claim 1, wherein the milling stage includes the use of 2 three roller milling combinations.

4. The process according to claim 1, wherein stage d) is a non-catalytic or auto-catalytic process.

5. The process according to claim 1, wherein the one-step physico-chemical treatment is an AFEX alkaline catalytic treatment.

6. The process according to claim 1, wherein the one-step physico-chemical treatment is an AHFEX alkaline catalytic treatment.

7. The process according to claim 4, wherein the one-step physico-chemical treatment is a STEX treatment.

8. The process according to claim 4, wherein the one-step physico-chemical treatment is a WEX treatment.

9. An integrated process for the production of cellulosic ethanol from a sugar cane biomass, consisting of the stages of: a) defibrating a sugar cane biomass; b) milling the defibrated sugar cane biomass, the milling stage characterized by at most 3 three-roller milling combinations, resulting in a saccharose content primary juice and a bagasse containing a residual amount of saccharose and a fibrous fraction; c) submitting the bagasse obtained in stage b) to a one-step physico-chemical treatment with addition of at least one chemical agent at conditions with severity level (S) is within the range from 3.70 to 4.50; d) hydrolyzing the treated sugar cane bagasse obtained from stage c) with an enzyme, such that a cellulosic hydrolysate is produced; and e) fermenting the the cellulosic hydrolysate from stage d), such that a cellulosic ethanol is produced; wherein the at least one chemical agent added at stage c) is selected from the group consisting of ammonia, ammonium hydroxide, water steam, water, and combinations thereof, and wherein stages d) and e) are sequential or concurrent stages.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIGS. 1 through 8 describe the various possible chemical and biochemical approaches pertaining to the integrated systems that are addressed in the present invention. FIGS. 1 through 4 describe approaches in which defibration and milling are used, while FIGS. 5 through 8 describe approaches in which defibration alone is used. There is a vast myriad of products and processes that can be configured and produced through the various productive arrangements, along with the use of techniques that involve physico-chemical processes (i.e., pre-treatments) and biochemical processes (e.g., enzymatic hydrolysis and fermentation) which, for example, encourage the production of carbohydrates (e.g., saccharose, glucose, and xylose), enzymes, and first- and second-generation ethanol, as well as carbohydrate derivatives (e.g., organic acids, polyols, and glycols). Likewise evident is the possibility of performing thermal, chemical, and thermo-chemical conversions of the solid residue (i.e., cellulignin) produced during the integrated process in a biorefinery setting, thereby enabling the generation of energy (through combustion), the production of liquid and gaseous fuels (through pyrolysis, gasification, and Fischer-Tropsch reactions), and the production of chemical specialty products having a high added value (through the oxidation of the lignin and carbohydrates).

(2) FIG. 9 illustrates the ethanol yield for different enzymatic hydrolysate combinations.

(3) FIG. 10 shows Typical Profile No. 1, with a gentle ramp-up and sudden decompression.

(4) FIG. 11 shows Typical Profile No. 2, with an intense ramp-up and sudden decompression.

(5) FIG. 12 shows Typical Profile No. 3, with an intermediate ramp-up and gentle decompression.

(6) FIG. 13 shows Typical Profile No. 4, with an intermediate ramp-up and sudden decompression.

(7) FIG. 14 shows the conversions obtained in the tests of the enzymatic reactivity of the pre-treated bagasses at different severity levels, with a gentle ramp-up and sudden decompression.

(8) FIG. 15 shows the composition of the pre-treated bagasse under different operating conditions, with a gentle ramp-up and sudden decompression.

(9) FIG. 16 shows the percentage of xylans in relation to the conversions obtained in the tests of the enzymatic reactivity of the pre-treated bagasses at different severity levels and under different operating conditions, with a gentle ramp-up and sudden decompression.

(10) FIG. 17 shows the composition of the pre-treated bagasse at different severity levels and under different operating conditions, with an intense ramp-up and sudden decompression.

(11) FIG. 18 shows the enzymatic conversions of the pre-treated bagasses at different severity levels, with an intense ramp-up and sudden decompression.

(12) FIG. 19 shows the composition of the bagasses that were pre-treated with steam, as produced at different severity levels and with different heating ramp-ups (both gentle and intense), with sudden decompression.

(13) FIG. 20 shows the enzymatic conversions of the cellulose in the bagasses that were pre-treated with steam, at different severity levels and with different heating ramp-ups (both gentle and intense), with sudden decompression.

(14) FIG. 21 shows the composition of the pre-treated bagasse at different severity levels and under different operating conditions, with an intermediate ramp-up and gentle decompression.

(15) FIG. 22 shows the enzymatic conversions of the pre-treated bagasses at different severity levels, with an intermediate ramp-up and gentle decompression.

(16) FIG. 23 shows the composition of the pre-treated bagasse at different severity levels and under different operating conditions, with an intermediate ramp-up, sudden decompression, and head space of 50%.

(17) FIG. 24 shows the enzymatic conversions of the pre-treated bagasses at different severity levels and under different operating conditions, with a typical profile consisting of an intermediate ramp-up, sudden decompression, and head space of 50%.

(18) FIG. 25 shows the conversions of the cellulose into glucose under different process conditions (enzymatic hydrolysis of the bagasse that was pre-treated with steam).

(19) FIG. 26 shows the typical profile for the WEX process, as conducted at a temperature of 190 C. for a period of 4 minutes.

(20) FIG. 27 shows the enzymatic hydrolysis yield of the bagasse that was pre-treated using the WEX process (both catalytic and non-catalytic) under different temperature conditions (195 C. to 215 C.), reaction times (4 to 16 minutes), and catalyst loads (0 to 1.6 grams per 100 grams of dry bagasse). The values are expressed in terms of the conversion of cellulose into glucose.

DETAILED DESCRIPTION OF THE INVENTION

(21) The purpose of the examples described here is solely to illustrate the goals of the invention, and not to limit its application.

(22) Lignocellulosic Plant Biomass

(23) The term lignocellulosic plant biomass covers all types of plants, namely, herbaceous biomass; crops such as C4 plants belonging to the Lolium, Spartina, Panicum, and Miscanthus genera, and combinations thereof; sugar cane, including bagasse (produced by the mill and/or by the diffuser, with bagasse from the diffuser being preferred); straw from cereal crops such as wheat, rice, rye, barley, oats, corn, and similar cereal crops (e.g., elephant grass (switchgrass); wood; banana-tree trunks and stems; cacti, and combinations thereof. Lignocellulosic materials may also consist of cardboard, sawdust, newsprint, and similar agro-industrial or municipal wastes.

(24) Plant biomasses of different origins may display individual differences, even if their overall chemical composition is relatively similar. Some variations in composition between different species, and within a single species, are due to environmental and genetic variability, as well as to the location of the plant tissue in different parts of the plant. Typically, approximately 35% to 50% of the plant consists of cellulose; 20% to 35% consists of hemicelluloses; and approximately 20% to 30% consists of lignin, while the remainder consists of smaller quantities of ash, soluble phenolic compounds, and fatty acids, as well as other constituents, known as extractives. The cellulose and the hemicelluloses in plant tissue consist of structural carbohydrates (e.g., glycans, xylans, and mannans), which are generally referred to as the saccharide fraction. Lignin is part of the phenolic fraction of plant biomass.

(25) The Pre-Treatment Process

(26) The present invention consists of the development of an extraction system associated with a pre-treatment process implemented under moderate conditions (i.e., conditions of reduced severity). Basically, it includes a process for the treatment of plant biomass by means of a sugar-cane defibration stage, followed by extraction of the sugar-rich juice from the plant biomass by means of milling or diffusion, supplemented by the (pre-)treatment of the plant biomass, as defibered and extracted (i.e., the bagasse) with chemical agents, within the context of the subsequent stages consisting of saccharification (i.e., the production of carbohydrates) and the conversion of the newly available carbohydrates through fermentative processes, for example, for the production of second-generation ethanol, in addition to the production of other products derived from the chemical and biochemical conversion of the carbohydrates that have been produced.

(27) In a preferred embodiment of the invention, the process includes the stages consisting of: a) Defibration of the plant biomass; b) Optional extraction of part of the juice by milling or diffusion, with the milling including up to 3 three-roller milling combinations; and c) Treatment of the solid defibered plant biomass from stage (b) with chemical agents at different levels of severity (S), within the range from 3.10 to 4.50.

(28) Defibration

(29) During the dehydration stage, the sugar-cane biomass is placed in a blade mill or knife mill (chopper), or a similar piece of equipment, such that there is a substantial increase in the exposed area (i.e., the contact surface) of the biomass, thereby maximizing the impregnation by the water of imbibition used in the extraction stage, as well as by the physico-chemical agents used in the pre-treatment stage. Satisfactory defibration provides satisfactory imbibition of the sugar cane, thereby promoting greater efficiency and a higher extraction yield of the juice during the milling stage, with a resulting increase in the production of sugar and of first-generation ethanol.

(30) Extraction

(31) The defibered sugar cane is treated and then placed in an extraction unit consisting of a maximum of 3 (three) three-roller milling combinations, and preferably 2 (two) milling combinations, in which the milling of the defibered sugar cane takes place in the presence of water of imbibition, so as to produce a liquid fraction (juice) and a solid fraction (the sugar-cane bagasse).

(32) In comparison with the conventional system, which uses 4 or 5 three-roller milling combinations, the simplified configuration of the equipment, as reflected here by the smaller number of rollers (i.e., three-roller milling combinations), embodies a substantial reduction in energy demand, due to the lower need for power to drive the three-roller milling combinations. Consequently, the lower energy demand results in a significant reduction in the amount of bagasse burned in the boiler (for the production of energy), thereby increasing the availability of this biomass for conversion into sugars and into second-generation ethanol. For example, a reduction of approximately 60% can be obtained in the energy demand of the extraction operations, which represents an overall energy saving (as well as processed bagasse) that, with the configuration adopted in the present invention, is potentially greater than 40%.

(33) Moderate Treatment

(34) After the defibration and milling stages, the solid fraction (i.e., the bagasse) undergoes a moderate (i.e., less severe) pre-treatment, with a view toward making available the carbohydrates that are present in the cellulose and hemicellulose fractions, including, in particular, glucose and xylose, within the context of the subsequent conversions (e.g., purification, hydrogenation, and fermentation), with a view toward the production of second-generation ethanol (i.e., cellulosic ethanol) and other products, for example. Thanks to the presence of residual carbohydrates in the biomass (including, in particular, the saccharose derived from the milling process), moderate processing conditions (e.g., temperature, pressure, and reaction time) must be employed, along with chemical agents such as catalysts (e.g., ammonia, ammonium hydroxide, and sulfur dioxide), so as to minimize the saccharide degradation and, consequently, the degradation of the overall production yield. These measures make it possible to produce pre-treated biomasses whose cellulose is highly accessible to the hydrolytic agents used in the saccharification process, while the degradation of the carbohydrates tends to take place at a reduced level.

(35) The present invention includes examples of the treatment of various biomasses (i.e., defibered sugar cane and/or bagasse from the second three-roller milling combination), using catalytic systems (e.g., alkaline pre-treatment with ammonia or ammonium hydroxide), in addition to non-catalytic and autocatalytic processes using steam or water as chemical agents.

(36) The products resulting from the treatment process can be used in various other processes, such as enzyme production, enzymatic hydrolysis, and fermentation, among others, in accordance with the various examples discussed hereinbelow.

(37) Severity Level (S)

(38) The level of severity of the treatment of the biomass according to the present invention is an index figure that reflects the pressure, temperature, and reaction time employed. For the purposes of the present invention, the severity level (S) is equivalent to Log R.sub.0.

(39) Enzyme Production

(40) The process of obtaining enzymes includes the submerged or semi-solid culture, in fermenters, of a specific microorganism in substrates containing, for example, pre-treated sugar-cane bagasse. The pre-inoculation stage is performed using the stock in a solid medium in a test tube, in which the spores are suspended in a culture medium. A typical composition of a preferred culture medium consists of pre-treated biomass, a source of carbohydrates (e.g., saccharose, purified sugar-cane juice, or treated molasses), a source of plant protein (e.g., soy protein), and chemical adjuvants and nutrients, such as ammonium sulfate, urea, potassium phosphate, magnesium sulfate, calcium chloride, surfactants, antibiotics, and anti-foaming agents. The volume of inoculum may vary, depending on the characteristics of the available equipment and on the desired duration of the process.

(41) The suspension of spores in culture medium is transferred, under completely aseptic conditions, from a test tube to the culture vials, and the culture vials are then transferred to an incubator table equipped with a shaking mechanism. The culture conditions typically include temperature ranging from 26 C. to 34 C., in processes implemented with mechanical shaking at a speed ranging from 80 rpm to 160 rpm, with aeration rates on the order of 6 vvm to 8 vvm,

(42) The process of enzyme production through fermentation requires a reaction time that is established in accordance with the enzyme formulation to be produced. In general, these processes require between 80 and 160 hours of operating time (i.e., loading, the reaction time, and unloading), also taking into consideration the intermediate operations consisting of checking and adjusting the pH, obtaining samples, and monitoring the aeration rate.

(43) The Fermentative Process

(44) The fermentation stage can be implemented after the enzymatic hydrolysis, by means of a process known as SHF (Separated Hydrolysis and Fermentation), or simultaneously with the hydrolysis, by means of a process known as SSF (Simultaneous Saccharification and Fermentation). Depending on the concentration of the sugars that are produced during the enzymatic hydrolysis, the decision may be made to add to the reaction medium a concentrated saccharide solution (e.g., molasses or sugar-cane juice), in a quantity ranging from 80 grams/liter to 820 grams/liter, and preferably between 120 grams/liter and 200 grams/liter.

(45) The present invention also contemplates the possibility of the simultaneous implementation of the enzymatic pre-treatment of the hemicelluloses, the enzymatic hydrolysis of the cellulose, and the fermentation, through a consolidated bioprocess (GBP) that uses the treated biomass as a substrate.

(46) A concentrated saccharide solution (known as a booster), which preferably consists of molasses or, optionally, sugar-cane juice, is preferably added to the fermenter at the start of the process or during the process, although the process can also be implemented without the addition of a saccharide solution. The sugar concentration of the saccharide booster solution ranges from 80 grams/liter to 820 grams/liter, and is preferably between 120 grams/liter and 200 grams/liter.

Example 1.Production of Carbohydrates and Ethanol from Sugar-Cane Bagasse Produced by Means of a Non-Conventional Preparation (Using Chopped Sugar Cane or Bagasse from the First or Second Set of Rollers), Using the AFEX/AHFEX (Ammonia or Ammonium Hydroxide Fiber Explosion) Alkaline Catalytic Pre-Treatment, Enzymatic Hydrolysis, and Ethanolic Fermentation

(47) The alkaline AFEX/AHFEX pre-treatment operation consists of loading the biomass (without any prior treatment, such as washing, milling, or granular metrics operation) [into a reactor]. After loading of the discontinuous reactor and during the heating process, the impregnation of the biomass with a chemical agent (i.e., ammonia or ammonium hydroxide) is begun. After the operational pressure and temperature (7.0 to 15.0 kgf/cm.sup.2 and 90 C. to 160 C.) have been reached, the reaction takes place, with the mixture being left to cook during the operational period (ranging from 10 minutes to 120 minutes). Then the discharge valve located at the base of the reactor is opened (either suddenly or in a controlled manner) so as to cause the decompression of the reactor, with the expulsion of the mass into a cyclone system or a tank for the collection of the pre-treated material.

(48) Table 1 shows the results of an integrated process for the production of carbohydrates, first-generation ethanol, and second-generation ethanol from chopped sugar cane and bagasse, pre-treated via AFEX/AHFEX and output by the second set of three-roller milling combinations. The Simultaneous Saccharification and Fermentation (SSF) technique was used, with cellulolytic enzymes (i.e., cellulases), -glucosidases, and hemicellulases, with a view toward the production of carbohydrates (e.g., glucose and xylose) from the bagasse or from the chopped sugar cane. In some cases, molasses was incorporated as a source of total reducing sugars (i.e., implementation of the boosting technique), in order to promote the reaction consisting of the biochemical conversion of the carbohydrates and ethanol.

(49) TABLE-US-00001 TABLE 1 A B C D E F Source of the sugars Fiber Fiber Fiber/ Fiber/ Molasses Molasses only only molasses molasses only only Type of fermentation SSF SSF SSF SSF Conv. Conv. Pre-treated wet biomass (g) 129.1 129.1 129.1 129.3 0.0 0.0 Solids load (%) 1.0 1.0 0.7 0.7 0.0 0.0 Juice or molasses load (g) 0.0 0.0 376.7 376.5 113.0 113.0 Cellulase (grams per 100 g 10.8 10.8 10.8 10.8 0.0 0.0 of biomass) -glucosidase (grams per 2.5 2.5 2.5 2.5 0.0 0.0 100 g of biomass) Hemicellulase (grams per 0.9 0.9 0.9 0.9 0.0 0.0 100 g of biomass) Inoculum (g) 26.9 26.9 38.6 38.6 5.0 5.0 Total sugar conc. (%) 1.6 1.6 10.0 9.9 12.0 12.0 Sugars in the juice or 0.0 0.0 119.9 119.9 36.0 36.0 molasses (g) Sugars in the fiber (g) 15.9 15.9 15.9 15.9 0.0 0.0 Cellulose conv. (%) 100 100 100 100 N/A N/A Dry yeast base (g) 9.0 9.0 13.0 13.0 2.0 2.0 Type of ethanol 2G 2G 1G/2G 1G/2G 1G 1G Fermentative yield (%) 53.3 57.9 77.2 76.7 71.6 69.9 1G: First-generation ethanol. 2G: Second-generation ethanol. SSF: Simultaneous Saccharification and Fermentation. Conv.: Conventional.

(50) As can be seen in FIG. 9, the combination of enzymatic hydrolysis and molasses tends to favor the performance of the microorganism (Saccharomices cerevisae) used in the fermentative process, reflecting a positive synergy between the first-generation ethanol process (which uses only molasses) and the second-generation ethanol process (which uses only fiber).

Example 2.Production of Carbohydrates from Sugar-Cane Bagasse Produced Through Conventional Milling Using STEX (Steam Explosion) Pre-Treatment in Non-Catalytic Systems

(51) The steam-based pre-treatment operation consists initially of loading the biomass (without any prior treatment, such as washing, milling, or granular metrics operation) [into a reactor]. After the discontinuous reactor is loaded, heating is begun through the injection of saturated steam (20 to 23 kgf/cm.sup.2) in direct contact with the biomass present in the reactor (see the typical operating profile shown in FIG. 10, so as to reach the operational pressure and temperature (12.0 to 20.0 kgf/cm.sup.2 and 160 C. to 220 C.), using an appropriate heating ramp-up. The reaction per se then takes place, with the mixture being left to cook during the reaction time (ranging from 2 minutes to 20 minutes). Then the discharge valve of the reactor is opened, so as to cause the sudden decompression of the reactor, with the expulsion of the mass into a cyclone system or a tank in which the pre-treated material is collected.

(52) For steam-based pre-treatment processes in catalytic and non-catalytic systems, the time required to reach the working pressure may contribute significantly to the severity of the process. Furthermore, the pressurization ramp-up, and consequently the temperature profile, may also be treated as a process variable that has a significant impact on the characteristics of the pre-treated biomass. The need to investigate different pressurization and heating profiles under different levels of severity requires an integrative approach to the severities for each time interval within an average temperature range, in accordance with the following equation:

(53) $\begin{array}{cc}{R}_0={}_{t1}^{t2}\exp \left(\frac{T-100}{14.75}\right)dt.& \mathrm{Equation}\left(1\right)\end{array}$
where t.sub.1 and t.sub.2 refer to the starting and ending times of the interval, expressed in minutes, for an average temperature T for the process interval, which temperature is expressed in C.

(54) The following examples refer to the steam-based pre-treatment processes that use sugar-cane bagasse produced by means of conventional milling, containing approximately 39% cellulose (37% to 41%), 22% xylans (18% to 26%), and 23% lignin that is insoluble in acid (17% to 26%). The processes were implemented under levels of severity (Log R.sub.0) ranging between 3.16 and 4.28 (14.0 to 18.5 kgf/cm.sup.2, and 0 to 10 minutes), in non-catalytic or autocatalytic systems, using the water contained in the original bagasse. Different pressurization profiles, and consequently different reactor heating profiles were investigated, which included a gentle ramp-up (1.10.5 kgf/cm.sup.2/minute), an intermediate ramp-up (2.80.5 kgf/cm.sup.2/minute), and an intense ramp-up (5.51.0 kgf/cm.sup.2/minute), and gentle and sudden decompressions applied at pressures on the order of 11.01.0 kgf/cm.sup.2 and at the threshold pressure, respectively. An attempt was also made to investigate the effect of the reactor loadincluding, in particular the equipment occupancy level (with head space of 0% and 50%)on the properties of the pre-treated bagasse. Table 2 shows the properties of the four typical profiles that were investigated, taking into consideration the type of ramp-up and decompression. Typical profiles can be seen in FIGS. 10 through 24. The operational variables and the severity of the process for each of the experiments that was conducted are shown in tables 3 through 6, which group together the experiments that were conducted for each of the typical profiles.

(55) TABLE-US-00002 TABLE 2 Typical profiles containing the type of ramp-up and decompression. Typical profile Ramp-up Decompression 1 Gentle Sudden (1.1 0.5 kgf/cm.sup.2/min.) 2 Intense Sudden (5.5 1.0 kgf/cm.sup.2/min.) 3 Intermediate Gentle (2.8 0.5 kgf/cm.sup.2/min.) 4 Intermediate Sudden (2.8 0.5 kgf/cm.sup.2/min.)

(56) The bagasse pre-treatment processes produce substrates with high cellulose contents and a high level of enzymatic reactivity under different process conditions, including reduced pressures on the order of 14 kgf/cm.sup.2. Maximum reactivity was displayed for pressure levels of 17 kgf/cm.sup.2 and a reaction time of 10 minutes, reflecting severities of nearly 4.30. It was observed that at this level of severity, a pre-treated bagasse was produced that had a lower xylan content and a higher glycan content. The intense and selective removal of the xylans tends to produce substrates with a high level of enzyme accessibility to the cellulosic matrix, resulting in elevated conversions into glucose. It was observed that the use of very severe conditions tends to increase the solubilization of the cellulose and the subsequent removal of the glycans to the liquid phase, in the form of glucose and degradation products, thereby impairing the overall productive yield.

(57) The following tables show the compositions of the bagasses that were pre-treated with steam, as produced under different process profiles in non-catalytic (or autocatalytic) systems. The yields of the processes for the production of carbohydrates by means of enzymatic hydrolysis (expressed in terms of conversion of cellulose into glucose), as performed on the various pre-treated bagasses using formulations of cellulases and -glucosidase, are shown separately.

(58) TABLE-US-00003 TABLE 3 Compositions, soluble solids, and yield of the enzymatic hydrolysis of the pre-treated bagasses, under different process operating conditions and severities, for experiments with a gentle ramp-up (1.1 0.5 kgf/cm.sup.2/minute) and sudden decompression. The head space was 0 (zero), and the solids load in the reactor was 71 kg/m.sup.3. Composition of the Yield of the pre-treated enzymatic hydrolysis bagasse (%) process (%) P (atm) t (min.) T ( C.) S Glycan Xylan Lignin 24 hours 48 hours 14.0 2 199 3.71 56.80 11.16 29.01 45.14 53.94 14.0 5 198 3.84 58.86 6.54 30.49 62.65 63.66 14.0 8 197 3.92 56.17 6.40 30.50 64.80 69.69 14.0 10 198 3.91 52.31 6.38 33.40 55.15 62.55 15.0 2 198 3.74 57.43 8.99 29.23 51.24 58.86 15.0 5 201 3.93 58.04 4.77 32.65 64.03 78.84 15.0 8 200 3.99 58.03 5.51 41.83 65.14 77.82 15.0 10 201 3.99 52.79 4.80 34.31 63.10 70.57 16.0 3 201 3.95 59.72 4.57 32.16 69.15 77.50 16.0 5 204 4.06 58.67 3.73 33.44 67.19 76.77 16.0 8 202 4.09 59.60 3.34 42.79 74.93 77.96 16.0 10 201 4.02 53.98 3.22 35.74 71.36 80.25 17.0 2 205 4.03 56.56 4.36 33.00 71.88 75.88 17.0 5 205 4.08 57.43 3.50 34.05 71.55 79.70 17.0 8 202 4.12 55.54 3.24 35.46 79.72 82.43 17.0 10 206 4.15 57.41 2.37 38.27 59.77 70.39 18.5 0 205 3.16 48.66 15.85 30.73 30.01 38.14 18.5 2.5 207 3.69 59.97 9.04 28.79 55.11 61.90 18.5 5 209 4.01 55.57 4.07 33.80 66.75 77.57 Yield of the enzymatic hydrolysis process, expressed in terms of the conversion of cellulose into glucose.

(59) TABLE-US-00004 TABLE 4 Compositions, soluble solids, and yield of the enzymatic hydrolysis of the pre-treated bagasses, under different process operating conditions and severities, for experiments with an intense ramp-up (5.5 1.0 kgf/cm.sup.2/minute) and sudden decompression. Head space: 0 (zero). Solids load: 71 kg/m.sup.3 in the reactor. Yield of the Composition of the enzymatic hydrolysis pre-treated bagasse (%) process (%) P (atm) T (min.) T ( C.) S Glycan Xylan Lignin 24 hours 48 hours 17.0 2 205 3.67 47.64 10.39 26.57 38.51 48.07 17.0 5 206 3.86 54.60 4.58 31.52 58.94 69.91 17.0 7 204 4.02 58.06 3.15 34.81 65.83 71.44 17.0 10 202 4.04 50.87 2.27 35.17 77.60 87.54

(60) TABLE-US-00005 TABLE 5 Compositions, soluble solids, and yield of the enzymatic hydrolysis of the pre-treated bagasses, under different process operating conditions and severities, for experiments with an intermediate ramp-up (2.8 0.5 kgf/cm.sup.2/minute) and gentle decompression (11.0 1.0 kgf/cm.sup.2). Head space: 0 (zero). Solids load: 71 kg/m.sup.3 in the reactor. Yield of the Composition of the enzymatic hydrolysis pre-treated bagasse (%) process (%) P (atm) T (min.) T ( C.) S Glycan Xylan Lignin 24 hours 48 hours 14.0 5 199 3.97 55.33 4.84 31.92 64.09 65.09 14.0 10 194 3.92 59.10 6.27 31.52 54.95 65.17 15.0 5 200 4.15 56.40 3.41 36.16 65.81 70.25 15.0 10 200 4.13 56.67 4.99 32.98 61.23 67.20 16.0 5 202 4.16 56.63 3.33 35.70 68.74 77.18 17.0 5 203 4.01 54.26 3.35 33.30 68.58 70.94 17.0 10 203 4.28 55.49 2.08 37.53 82.99 81.98

(61) TABLE-US-00006 TABLE 6 Compositions, soluble solids, and yield of the enzymatic hydrolysis of the pre-treated bagasses, under different process operating conditions and severities, for experiments with an intermediate ramp-up (2.8 1.0 [sic] kgf/cm.sup.2/ minute) and sudden decompression. Head space: 50%. Solids load: 46 kg/m.sup.3 in the reactor. Yield of the Composition of the enzymatic hydrolysis pre-treated bagasse (%) process (%) P (atm) T (min.) T ( C.) S Glycan Xylan Lignin 24 hours 48 hours 15.0 5 200 3.72 48.93 7.37 30.12 75.84 80.54 15.0 10 200 4.00 50.19 3.98 33.55 75.41 93.40 17.0 5 206 3.94 54.84 4.83 32.78 68.89 72.63 18.5 2.5 208 3.76 52.7 5.8 31.1 57.38 74.66

Example 3.Production of Carbohydrates from Sugar-Cane Bagasse Produced Through Conventional Milling Using STEX (Steam Explosion) Pre-Treatment in Autocatalytic Systems

(62) Tables 7 and 8 show the composition of the bagasse that was pre-treated with steam in systems that were auto-catalyzed with acetic acid obtained from the deacetylation of the hemicelluloses (xylans). As can be seen, the said bagasse displayed a significantly higher glycan content and a significantly lower xylan content than had been detected in the original biomass. This change is due essentially to the intense and selective removal of the hemicelluloses during the process, as also indicated by the acidity of the resulting biomass (with a pH within the range from 3 to 4), as well as by the higher xylose content and the reduced glucose content of the soluble solids. As can be seen, there is a clear predominance of non-saccharide compounds among the soluble solids, indicating the likely conversion of carbohydrates (particularly xylose and arabinose) and of lignin into chemical species such as organic acids (e.g., acetic acid) and phenolic compounds. In summary, it is clear that the pre-treatment of the bagasse, as performed under the operational conditions described here, is characterized by elevated productive efficiency, based on the elevated, intense, and selective extraction of hemicelluloses, with a reduced cellulosic loss in the fiber.

(63) TABLE-US-00007 TABLE 7 Composition of the pre-treated bagasse. Constituent % Humidity 58.3 Total solids 41.7 Insoluble solids (fiber) 79.3 Glycans 55.4 Xylans 3.2 Lignin 35.4 Other insoluble solids 6.0 Soluble solids (SS) 20.7 Glucose 3.8 Xylose 14.5 Arabinose 0.8 Other soluble solids 80.9
Table 8 and FIG. 25 show the conversions of the cellulose into glucose, as obtained through the hydrolysis of the pre-treated bagasse with different enzyme loads, processing times, and solids loads, using cellulose and -glucosidase.

(64) TABLE-US-00008 TABLE 8 Enzymatic hydrolysis of the bagasse pre-treated with steam. Solids Cellulase load Hydrolysis Cellulose load (FPU*/g of time conversion Condition (%) fiber) (hours) (%) 1 8 7.5 24 38 2 8 7.5 48 55 3 8 15.0 24 61 4 8 15.0 48 74 5 2 15.0 24 80 6 2 15.0 48 82 Conversion of cellulose into glucose. *[FPU = Filter-paper unit.]

Example 4.Production of Carbohydrates from Sugar-Cane Bagasse Using the WEX (Wet Explosion or Water Explosion) Pre-Treatment in Catalytic and Non-Catalytic (Autocatalytic) Systems

(65) The WEX (Water Explosion or Wet Explosion) pre-treatment operation initially consists of loading the reactor with the biomass along with the reagents. Unlike the STEX process, in the WEX process heating is done without an injection of steam into the biomass. In this system, part of the water present in the reaction medium is vaporized, thereby producing in camera steam during the period in which the operational pressure and temperature are reached by means of an appropriate heating ramp-up. Next, the reaction per se takes place, with the mixture being left to cook during the reaction time. The reactor is then emptied by means of the opening of the valve, which causes the sudden decompression of the equipment and the resulting discharge of the pre-treated biomass into a collection tank.

(66) For WEX pre-treatment processes in catalytic and non-catalytic systems, the time required to reach the working temperature affects the overall severity of the process, with an impact on the properties of the pre-treated biomass. Different pressurization and heating profiles under different levels of severity can be integrated for each time interval within an average temperature range, in accordance with the following equation, which characterizes the severity of the process:

(67) $\begin{array}{cc}{R}_0={}_{t1}^{t2}\exp \left(\frac{T-100}{14.75}\right)dt.& \mathrm{Equation}\left(1\right)\end{array}$
where t.sub.1 and t.sub.2 refer to the starting and ending times of the interval, expressed in minutes, for an average temperature T for the process interval, which temperature is expressed in C.

(68) The following examples refer to the WEX pre-treatment processes that use sugar-cane bagasse produced by means of conventional milling, containing approximately 39% cellulose (37% to 41%), 22% xylans (18% to 26%), and 23% lignin that is insoluble in acid (17% to 26%). The processes were conducted in non-catalytic or autocatalytic systems, using the water contained in the original bagasse itself. Different operating conditions of temperature (190 C. to 210 C.), reaction time (4 to 12 minutes), catalyst load (0 to 1.6 g per 100 g), hydromodule or liquid-to-solid ratio (10 to 20) and head space (0% or 50%) were used in typical profiles, as indicated in Table 9 and in FIG. 26.

(69) TABLE-US-00009 TABLE 9 Experimental conditions used in certain catalytic and non-catalytic WEX processes. Hydro- Temperature Time H.sub.3PO.sub.4 conc. module Head space No. ( C.) (min.) (g/100 g BS) (L/S) (%) 1 190 4 0 10 50 2 210 4 0 10 0 3 190 12 0 10 0 4 210 12 0 10 50 5 190 4 1 10 0 6 210 4 1 10 50 7 190 12 1 10 50 8 210 12 1 10 0 9 190 4 0 20 50 10 210 4 0 20 0 11 190 12 0 20 0 12 210 12 0 20 50 13 190 4 1 20 0 14 210 4 1 20 50 15 190 12 1 20 50 16 210 12 1 20 0 17 200 8 0.5 15 25 18 200 8 0.5 15 25 19 200 8 0.5 15 25 20 200 8 0.5 15 25

(70) Table 10 and FIG. 27 show the principal productive and operating parameters of the WEX process (catalytic and non-catalytic) for the pre-treatment of the bagasse. Among these parameters, H refers to the hydromodule (i.e., the liquid-to-solid ratio); HS refers to the head space; and C refers to the catalytic load that was employed.

(71) TABLE-US-00010 TABLE 10 Productive and operating parameters of the WEX process (catalytic and non-catalytic) for the pre-treatment of the bagasse. Head Hydro- Recovered Recovered Temp. Time Catalytic load space module fiber soluble solids Losses ( C.) (min.) (g/100 g BS) (%) (L/S) (%) (%) (%) 190 4 0 50 10 64 14 21 20 83 10 7 1 0 10 72 15 12 20 62 12 25 12 0 0 10 59 13 28 20 67 11 21 1 50 10 62 12 25 20 65 13 22 200 8 0.5 25 15 50 11 39 15 65 10 25 15 54 12 34 15 58 8 34 210 4 0 0 10 59 15 26 20 48 10 42 1 50 10 58 9 33 20 74 10 16 12 0 50 10 56 6 38 20 52 9 40 1 0 10 57 5 38 20 49 9 42 H: Hydromodule. HS: Head space. C: Catalytic load.