Method and arrangement for controlling enzymatic hydrolysis

Abstract

A method for controlling enzymatic hydrolysis of biomass-derived feedstock in a manufacturing process of a chemical bioproduct is disclosed. The enzymatic hydrolysis may take place in a hydrolysis reaction mixture. The hydrolysis reaction mixture may comprise solid matter. The method may comprise performing at least one Brix measurement on the hydrolysis reaction mixture; and controlling a dosing of at least one enzyme into the hydrolysis reaction mixture at least partially based on the results obtained from the at least one Brix measurement; wherein the results indicate a content of one or more soluble carbohydrates in the hydrolysis reaction mixture, and wherein the controlling of the dosing of the at least one enzyme into the hydrolysis reaction mixture is performed in order to affect at least the conversion of cellulose and optionally hemicellulose into monomeric carbohydrates in the hydrolysis reaction mixture.

Description

[0001] METHOD AND ARRANGEMENT FOR CONTROLLING ENZYMATIC

[0002] HYDROLYSIS

[0003] TECHNICAL FIELD

[0004] The present disclosure relates in general to a method and arrangement for controlling enzymatic hydrolysis of biomass-derived feedstock in a manufacturing process of a chemical bioproduct .

[0005] BACKGROUND

[0006] The production of biomass-based chemical bioproducts may use , for example , wood particles as the main raw material . In a biomass-to-sugar process , the wood particles or other biomass may be subj ected to various kinds of pretreatments , such as washing and impregnating with water, acid catalyst , and / or other liquids , and subj ected to elevated temperature and pressure in order to prepare the material for later steps of the process . The later steps may involve , for example , enzymatic hydrolysis , from which sugars ( carbohydrates ) obtained by the hydrolysi s may be fed further to other processes . Such other processes may involve the production of e . g . glycols . The enzymatic hydrolysis step may also produce lignin as one of its outputs .

[0007] Controlling the enzymatic hydrolysis may involve a number of uncertainties . The process may be designed for certain nominal enzyme loading and activity, but how accurately these enable achieving a target level of carbohydrate monomer content in a given time may depend on e . g . how success ful the preceding pretreatment step was in preparing the material flow . Enzyme batches may also vary to some extent . It would be beneficial to be able to react in real time ( or at least as quickly as possible ) to detected deviations from the expected progression of the process . However, it is di f ficult to obtain accurate information of the current status of each step in the process in real time . Any measurement method that is to be appl ied should be applicable to prolonged operation in the harsh conditions of an industrial environment , which typically makes it di f ficult to utili ze instruments built for use in laboratory conditions .

[0008] SUMMARY

[0009] This Summary is provided to introduce a selection of concepts in a s impli f ied form that are further described below in the Detailed Description . This Summary is not intended to identi fy key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter .

[0010] A method for controlling enzymatic hydrolysis of biomass-derived feedstock in a manufacturing process of a chemical bioproduct is disclosed . The enzymatic hydrolysis may take place in a hydrolysis reaction mixture . The hydrolysis reaction mixture may comprise solid matter . The method may comprise performing at least one Brix measurement on the hydrolysis reaction mixture ; and controlling a dosing of at least one enzyme into the hydrolysis reaction mixture at least partially based on the results obtained from the at least one Brix measurement ; wherein the results indicate a content of one or more soluble carbohydrates in the hydrolysis reaction mixture , and wherein the controlling of the dosing of the at least one enzyme into the hydrolysis reaction mixture is performed in order to af fect at least the conversion of cellulose and optionally hemicellulose into monomeric carbohydrates in the hydrolysis reaction mixture . BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings , which are included to provide a further understanding of the embodiments and constitute a part of this speci fication, illustrate various embodiments . In the drawings :

[0012] Figure 1 illustrates schematically a manufacturing process of a chemical bioproduct from b i oma s s ;

[0013] Figure 2 illustrates the process steps of an exemplary enzymatic hydrolysis process ;

[0014] Figure 3 illustrates schematically a method and arrangement for controlling enzymatic hydrolysis of a biomass-derived feedstock in a manufacturing process of a chemical bioproduct ;

[0015] Figure 4A shows Brix values obtained for two sets of Brix measurements ;

[0016] Figure 4B shows ABx for the same two sets of Brix measurements ;

[0017] Figure 5A shows Brix values obtained for two sets of Brix measurements ; and

[0018] Figure 5B shows ABx for the same two sets of Brix measurements .

[0019] DETAILED DESCRIPTION

[0020] A method for controlling enzymatic hydrolysis of biomass-derived feedstock in a manufacturing process of a chemical bioproduct is disclosed . The enzymatic hydrolysis may take place in a hydrolysis reaction mixture . The hydrolysis reaction mixture may comprise solid matter .

[0021] The method may comprise performing at least one Brix measurement on the hydrolysis reaction mixture ; and controlling a dosing of at least one enzyme into the hydrolysis reaction mixture at least partially based on the results obtained from the at least one Brix measurement; wherein the results indicate a content of one or more soluble carbohydrates in the hydrolysis reaction mixture, and wherein the controlling of the dosing of the at least one enzyme into the hydrolysis reaction mixture is performed in order to affect at least the conversion of cellulose and optionally hemicellulose into monomeric carbohydrates in the hydrolysis reaction mixture.

[0022] The biomass-derived feedstock may be fed into the hydrolysis reaction mixture. It may comprise solid matter. The solid matter may include solid particles derived from the biomass. The solid matter may comprise e.g. lignin, solid cellulose particles, and / or hemicellulose (e.g. xylan) . These, or any one of these, may be in the form of solid particles. The solid matter may be understood as referring to solid, undissolved particles suspended in the hydrolysis reaction mixture.

[0023] Solid matter (i.e. solid particles suspended in the hydrolysis reaction mixture) render such hydrolysis reaction mixtures unsuitable as such for many analysis methods.

[0024] However, with the present method and arrangement, it is possible to obtain measurements directly from the hydrolysis reaction mixture, even when it contains solid matter, without the need to e.g. filter and / or wash samples of the hydrolysis reaction mixture.

[0025] Thus the at least one Brix measurement, or a plurality of Brix measurements, may, in some embodiments, be performed by obtaining at least one sample, or a plurality of samples, from the hydrolysis reaction mixture, and performing the at least one Brix measurement, or the plurality of Brix measurements, from the at least one sample, or the plurality of the samples; wherein the sample (s) is / are untreated. The untreated sample (s) comprise (s) the solid matter present in the hydrolysis reaction mixture. In other words, any solid matter present in the hydrolysis reaction mixture has not been removed, for example by centrifugation or filtering, but remains in the untreated sample.

[0026] Thus the at least one Brix measurement, or a plurality of Brix measurements, may, in some embodiments, be performed on the untreated hydrolysis reaction mixture.

[0027] The measurement capability may be arranged directly into the reactor in which the enzymatic hydrolysis takes place.

[0028] Thus the at least one Brix measurement, or a plurality of Brix measurements, may be performed continuously or continually or repeatedly, for example at regular or irregular time intervals, on the hydrolysis reaction mixture while the enzymatic hydrolysis is ongoing in the hydrolysis reaction mixture. This may allow for monitoring, following up and controlling the enzymatic hydrolysis in real time. This may also allow for optimizing the dosage of the at least one enzyme and thereby minimize the costs of the enzymatic hydrolysis. For example, enzyme batches may vary. With the present method and arrangement, it may be possible to monitor, follow up and control the enzymatic hydrolysis in situations in which enzymes exhibit variability.

[0029] Dissolution of soluble carbohydrates and other sugars in water changes its optical properties, in particular its refractive index and the extent to which it rotates the plane of linearly polarized light. Degrees Brix (symbol °Bx) or other Brix values, provided by a Brix measurement apparatus, may thus be used as a measure of dissolved solids , such as soluble carbohydrates , in a liquid . A refractometer may thus be calibrated such that it reads in °Bx . In the present method, the exact Brix values , such as °Bx, or the exact content of the soluble carbohydrates in the hydrolysis reaction mixture may not be important ; the Brix values , such as °Bx, measured may be used as a relative rather than absolute measure indicative of the content of the one or more soluble carbohydrates . Thus the at least one Brix measurement may be indicative of the conversion of cellulose , and optionally hemicellulose ( i f present ) , into monomeric carbohydrates , which may be soluble in the hydrolysis reaction mixture .

[0030] The method may comprise performing a plurality of Brix measurements on the hydrolysis reaction mixture at a plurality of instants during the enzymatic hydrolysis , for example at regular or irregular time intervals . Such Brix measurements may allow for following up on the progression of the enzymatic hydrolysis .

[0031] The method may comprise performing Brix measurements on the hydrolysis reaction mixture continuously during the enzymatic hydrolysis . In other words , continuous Brix measurements may be performed on the hydrolysis reaction mixture during the enzymatic hydrolysis .

[0032] The at least one Brix measurement , or the plurality of the Brix measurements , or the Brix measurements performed continuously, may be measured in-line .

[0033] The at least one Brix measurement , or the plurality of Brix measurements , or the Brix measurements performed continuously, may be performed using a refractometer .

[0034] The method may comprise performing the at least one Brix measurement , or the plurality of Brix measurements, or the Brix measurements performed continuously, directly on the hydrolysis reaction mixture in which the enzymatic hydrolysis is currently taking place.

[0035] The enzymatic hydrolysis may take place in the hydrolysis reaction mixture in a reactor containing the hydrolysis reaction mixture. The at least one Brix measurement, or the plurality of Brix measurements, or the Brix measurements performed continuously, may be performed in the reactor or immediately downstream thereof. The reactor may comprise a circulation loop circulating the hydrolysis reaction mixture from the reactor and back thereto. Alternatively or additionally, the at least one Brix measurement, or the plurality of Brix measurements, or the Brix measurements performed continuously, may be performed in the circulation loop circulating the hydrolysis reaction mixture from the reactor and back thereto .

[0036] The temperature of the hydrolysis reaction mixture may be in the range of about 40 - 55 °C, preferably in the range of about 45 - 55 °C, more preferably in the range of about 50 - 55 °C. The at least one Brix measurement, or the plurality of the Brix measurements, or the Brix measurements performed continuously, may thus be performed at such a temperature . pH of the hydrolysis reaction mixture may be e.g. in the range of about 4.5 - 5.5. The pH may be selected based on e.g. the optimal pH for the activity of the at least one enzyme.

[0037] The biomass-derived feedstock may be a woodbased feedstock and / or derived from a wood-based feedstock. The biomass, from which the biomass-derived feedstock may be derived, may be wood material, e.g. wood particles, such as pretreated (e.g. prehydrolysed) wood particles. The wood material may be selected from a group consisting of hardwood, softwood, and any combination thereof. The wood material may e.g. originate from pine, poplar, beech, aspen, spruce, birch, eucalyptus, ash, or any combination or mixture thereof. The wood material may also be any combination or mixture of these. The wood material may comprise or be hardwood. In other words, the biomass-derived feedstock may be a hardwood- derived feedstock. The wood material may be broadleaf wood due to its relatively high inherent sugar content, but the use of other kinds of wood is not excluded .

[0038] The biomass-derived feedstock may thus comprise or be pretreated wood particles, for example pre-hydrolysed wood particles. The biomass-derived feedstock may be derived from pretreated wood particles, for example pre-hydrolysed wood particles.

[0039] The pretreatment may comprise pre-steaming of a wood-based feedstock such as wood particles, with steam having e.g. a temperature of 100 - 130 °C at atmospheric pressure. The pretreatment may further comprise subjecting the wood-based feedstock, such as wood particles, to at least one impregnation treatment with impregnation liquid to form an impregnated woodbased feedstock. The impregnation liquid may comprise water, at least one acid, at least one alkali, at least one alcohol, or any combination or mixture thereof. The at least one acid may be selected from a group consisting of inorganic acids, such as sulphuric acid (H2SO4) , nitric acid, phosphoric acid; organic acids, such as acetic acid, lactic acid, formic acid, carbonic acid; and any combination or mixture thereof. For example, the impregnation liquid may comprise sulphuric acid, e.g. dilute sulphuric acid. The impregnation liquid may act as a catalyst in affecting the hydrolysis of the hemicellulose in the wood-based feedstock. The impregnation treatment may be carried out at a temperature of 20 - 99 °C for 5 seconds - 60 minutes, or 0.5 - 45 minutes, or 1 - 30 minutes. If the impregnation treatment is inefficient, shives may end up in the enzymatic hydrolysis, thereby increasing the average particle size of the solid matter. This may render the the Brix measurement ( s ) more challenging .

[0040] The impregnated feedstock may then be subjected to a steam explosion treatment. The steam explosion treatment may be carried out by treating the impregnated wood-based feedstock with steam having a temperature of 130 - 240 °C e.g. under a pressure of 0.17 - 3.25 MPaG followed by a sudden, explosive decompression of the feedstock. The feedstock may be treated with the steam e.g. for 1 - 20 minutes before the sudden, explosive decompression of the steam- treated feedstock. As a result of the hemihydrolysis of the feedstock affected by the steam explosion treatment, the hemicellulose present in the wood chips of the feedstock may become hydrolyzed or degraded into e.g. xylose oligomers and / or monomers. The hemicellulose comprises polysaccharides such as xylan, mannan and glucan. Xylan is thus hydrolyzed into xylose, which is a monosaccharide.

[0041] Thus, steam explosion of the feedstock may result in the formation of an output stream. The output stream from the steam explosion may be subjected to steam separation. The output stream from the steam explosion may be mixed or combined with a liquid, e.g. water, to form a slurry. The slurry may comprise a liquid phase and a solid phase. The slurry may be separated into a liquid fraction (which may comprise C5 sugars from hydrolyzed hemicellulose as well as soluble lignin and other by-products) and a fraction comprising solid cellulose particles (and lignin) .

[0042] The fraction comprising solid cellulose particles may have a total dry matter content of 15 - 50 weight-% . The fraction comprising solid cellulose particles may, in addition to cellulose , comprise lignin . As the C5 sugars may be ef ficiently removed with the crude liquid fraction, the fraction comprising solid cellulose particles may comprise carbohydrates such as solid C6 sugars . The fraction comprising solid cellulose particles may also comprise other carbohydrates and other components . The fraction comprising solid cellulose particles may also comprise an amount of C5 sugars .

[0043] I f the liquid fraction comprising C5 sugars is not separated, then the Brix value at the beginning of the enzymatic hydrolysis may be higher, as there may be more soluble components present prior to the enzymatic hydrolysis . The washing of f of the C5 sugar containing liquid fraction may therefore reduce the amount of solubles in the enzymatic hydrolysis . Further, the soluble C5 sugars present in the enzymatic hydrolysis may also inhibit the enzymatic hydrolysis . Separation of the liquid fraction comprising C5 sugars may thus improve the ef ficiency of the enzymatic hydrolysis , and the C6 sugars resulting from the enzymatic hydrolysis may have a higher purity .

[0044] The separated and recovered fraction comprising solid cellulose particles may be further puri fied or washed before being subj ected to enzymatic hydrolysis as the biomass-derived feedstock .

[0045] The hydrolysis reaction mixture may comprise at least about 3 % (w / w) , or about 3 - 17 % (w / w) of the solid matter . The hydrolysis reaction mixture may preferably comprise at least about 5 % (w / w) , or about 5 - 16 % (w / w) ; more preferably, at least about 7 % (w / w) , or about 7 - 15 % (w / w) of the solid matter . The Brix measurement ( s ) may work well within such amounts of the solid matter, and the volume of the hydrolysi s reaction mixture does not need to be overly large and dilute . A higher solid matter content may be challenging to handle due to e.g. high viscosity. A solid matter content of about 15 % (w / w) at the beginning of the enzymatic hydrolysis may be optimal in view of process economy (e.g. energy consumption, reactor volume) and still technically feasible in an industrial scale.

[0046] Even though the biomass-derived feedstock may be pre-treated prior to the enzymatic hydrolysis, an amount of solid matter may remain in the biomass- derived feedstock and consequently in the hydrolysis reaction mixture. The solid matter may include solid particles derived from the biomass. The solid matter may comprise e.g. lignin, solid cellulose particles, and / or hemicellulose (e.g. xylan) . These, or any one of these, may be in the form of solid particles.

[0047] The solid matter in the biomass-derived feedstock may have e.g. an average particle size of 0.2 mm or less. The average particle size may be determined using the standard TAPPI T271. The biomass- derived feedstock may comprise fiber particles. Such fiber particles may have e.g. an average particle size of 0.2 mm or less.

[0048] The enzymatic hydrolysis may be performed in batches or as a continuous process.

[0049] The at least one enzyme may be selected from a group consisting of cellulases, hemicellulases, laccases, lytic polysaccharide monooxygenases (LPMO) , and lignolytic peroxidases. Cellulases are multiprotein complexes consisting of synergistic enzymes with different specific activities that can be divided into exo- and endocellulases (glucanase) and p- glucosidase (cellobiose) . The at least one enzyme may be either a commercially available cellulase mix or manufactured on-site. The at least one enzyme may be dosed into the reactor.

[0050] The enzymatic reaction in the enzymatic hydrolysis may decrease the pH, and by shortening the length of the cellulose fibers, it may also decrease the viscosity of the hydrolysis reaction mixture. Subjecting the biomass-derived feedstock comprising solid cellulose particles to enzymatic hydrolysis may result in cellulose being transformed into glucose monomers with enzymes. Lignin present in the biomass- derived feedstock comprising solid cellulose particles may remain essentially in solid form.

[0051] Enzymatic hydrolysis may result in the formation of a hydrolysis product. The hydrolysis product may be separated into a solid fraction comprising lignin and a liquid carbohydrate fraction e.g. by a solid-liquid separation process to recover the liquid carbohydrate fraction.

[0052] In the present method, the exact °Bx or the exact content of the soluble carbohydrates in the hydrolysis reaction mixture may not be important; the degrees Brix measured may be used as a relative rather than absolute measure. The presence of the solid matter in the hydrolysis reaction mixture may have an effect on the absolute Brix values, such as °Bx values, obtained. Therefore, the results of the at least one Brix measurement, or the plurality of Brix measurements, or the Brix measurements performed continuously, may be obtained e.g. as a change in the Brix values, such as °Bx values, over time, or as a rate of change of the Brix values over time. The rate of change of the Brix values, i.e. ABx, may indicate a change of Brix values between two instants. For a particular solid matter content, a reference curve indicating preferred Brix value (s) , or preferred rate of change of the Brix values, may be determined. A high rate of change of the Brix values may be indicative of overdosing of the at least one enzyme. A low rate of change of the Brix values may be indicative of underdosing of the at least one enzyme or low activity of the at least one enzyme. Both or either of the Brix value ( s ) and the rate of change of the Brix values may be utili zed as the results of the at least one Brix measurement , or the plurality of Brix measurements , or the Brix measurements performed continuously .

[0053] For example , the results of the at least one Brix measurement , or the plurality of Brix measurements , or the Brix measurements performed continuously, may be adj usted such that the Brix values , such as the °Bx, measured at a starting point of the enzymatic hydrolysis is set to 0 .

[0054] Even the results of a single Brix measurement may indicate the content of the one or more soluble carbohydrates in the hydrolysis reaction mixture , for example i f the Brix measurement is performed at or near the end of the enzymatic hydrolysis . Then the results may indicate how ef ficient the conversion of cellulose and optionally hemicellulose into monomeric carbohydrates has been . However, it may be beneficial to perform a plurality of Brix measurements at a plurality of instants , or to perform Brix measurements continuously, at the early stages and during the enzymatic reaction, to allow for more ef ficiently controll ing the dosing of the at least one enzyme into the hydrolysis reaction mixture even during the enzymatic hydrolysis e . g . in the same batch . Results of Brix measurements performed at the early stages of the enzymatic reaction may also predict the content o f the one or more soluble carbohydrates in the hydrolysis reaction mixture at the end of the enzymatic hydrolysis .

[0055] An arrangement for controlling enzymatic hydrolysis of biomass-derived feedstock in a manufacturing process of a chemical bioproduct is also disclosed .

[0056] The arrangement may comprise at least one reactor for subj ecting the biomass-derived feedstock to enzymatic hydrolysis , the enzymatic hydrolysis taking place in a hydrolysis reaction mixture contained in the at least one reactor, wherein the hydrolysis reaction mixture comprises solid matter, additional process equipment upstream and downstream of the at least one reactor in the process , a Brix measurement apparatus configured to perform at least one Brix measurement on the hydrolysis reaction mixture , and a process controller coupled to receive measurement results from the Brix measurement apparatus , wherein said process controller is configured to control a dosing of at least one enzyme into the hydrolysis reaction mixture at least partially based on the results received in order to af fect the conversion of cellulose and hemicellulose into monomeric carbohydrates in the hydrolysis reaction mixture .

[0057] The arrangement and / or the at least one reactor may further comprise means for stirring the hydrolysis reaction mixture , such as a mixing device . Such means may create suf ficient turbulence of the hydrolysis reaction mixture during the enzymatic hydrolysis .

[0058] The Brix measurement apparatus may be configured to perform a plurality of Brix measurements on the hydrolysis reaction mixture at a plurality of instants during the enzymatic hydrolysis .

[0059] The Brix measurement apparatus may be configured to perform Brix measurements on the hydrolysis reaction mixture continuously during the enzymatic hydrolysis .

[0060] The Brix measurement apparatus may be configured to perform the at least one Brix measurement , or the plurality of Brix measurements , or the Brix measurements performed continuously, directly on the hydrolysis reaction mixture in which the enzymatic hydrolysis is currently taking place .

[0061] The Brix measurement apparatus may comprise or be a refractometer .

[0062] The Brix measurement apparatus may be configured to perform the at least one Brix measurement , or the plurality of Brix measurements , or the Brix measurements performed continuously, on the hydrolysis reaction mixture in the reactor or immediately downstream thereof . Alternatively or additionally, the at least one reactor may comprise a circulation loop configured to circulate the hydrolysis reaction mixture from the reactor and back thereto , and the Brix measurement apparatus may be configured to perform the at least one Brix measurement , or the plurality of Brix measurements , or the Brix measurements performed continuously, on the hydrolysis reaction mixture in the circulation loop .

[0063] Any embodiments described in thi s speci fication in the context of the method may also be understood as being described in the context of the arrangement .

[0064] EXAMPLES

[0065] Reference will now be made in detail to various embodiments , an example of which is illustrated in the accompanying drawing .

[0066] The description below discloses some embodiments in such a detail that a person skilled in the art is able to utili ze the embodiments based on the disclosure . Not all steps or features of the embodiments are discussed in detail , as many of the steps or features will be obvious for the person skilled in the art based on this speci fication . Figure 1 illustrates schematically a manufacturing process of a chemical bioproduct from biomass , such as wood material . The process may be roughly divided into a wood handling phase 101 , a wood-to-sugar phase 102 , and a sugar-to-chemical phase 103 . The wood material may be selected from a group consisting of hardwood, softwood, and any combination thereof . The wood material may e . g . originate from pine , poplar, beech, aspen, spruce , or birch . The wood material may also be any combination or mixture of these . The wood material may be broadleaf wood due to its relatively high inherent sugar content , but the use of other kinds of wood is not excluded .

[0067] The wood handling phase 101 may comprise mainly mechanical processing, such as debarking 111 and chipping 112 , in order to obtain a wood-based feedstock .

[0068] The wood-to-sugar phase 102 , which is also called the wood-to-sugar process , may comprise a pretreatment in which the wood-based feedstock from the wood handling phase 101 may be taken through stages such as impregnating 121 , hemihydrolysis 122 , and steam explosion 123 in order to break down the structure of the wood material and to remove the C5 sugars at least partially . The pretreatment may comprise presteaming of a wood-based feedstock with steam having a temperature of 100 - 130 ° C at atmospheric pressure . The pretreatment may further comprise subj ecting the wood-based feedstock to at least one impregnation treatment , i . e . impregnating at 121 , with impregnation liquid to form an impregnated wood-based feedstock . The impregnation liquid may comprise water, at least one acid, at least one alkali , at least one alcohol , or any combination or mixture thereof . The at least one acid may be selected from a group consisting of inorganic acids , such as sulphuric acid (H2SO4 ) , nitric acid, phosphoric acid; organic acids , such as acetic acid, lactic acid, formic acid, carbonic acid; and any combination or mixture thereof. For example, the impregnation liquid may comprise sulphuric acid, e.g. dilute sulphuric acid. The impregnation liquid may act as a catalyst in affecting the hydrolysis of the hemicellulose in the wood-based feedstock. The impregnation treatment may be carried out at a temperature of 20 - 99 °C for 5 seconds - 60 minutes, or 0.5 - 45 minutes, or 1 - 30 minutes.

[0069] At 123, the impregnated feedstock may then be subjected to steam explosion treatment. The steam explosion treatment may be carried out by treating the impregnated wood-based feedstock with steam having a temperature of 130 - 240 °C e.g. under a pressure of 0.17 - 3.25 MPaG followed by a sudden, explosive decompression of the feedstock. The feedstock may be treated with the steam e.g. for 1 - 20 minutes before the sudden, explosive decompression of the steam- treated feedstock. As a result of the hemihydrolysis of the feedstock affected by the steam explosion treatment, the hemicellulose present in the wood chips of the feedstock may become hydrolyzed or degraded into e.g. xylose oligomers and / or monomers. The hemicellulose comprises polysaccharides such as xylan, mannan and glucan. Xylan is thus hydrolyzed into xylose that is a monosaccharide.

[0070] Thus, steam explosion of the feedstock may result in the formation of an output stream. The output stream from the steam explosion 123 may be subjected to steam separation. The output stream from the steam explosion may be mixed or combined with a liquid, e.g. water, to form a slurry. The slurry may comprise a liquid phase and a solid phase. The slurry may be separated into a liquid fraction and a fraction comprising solid cellulose particles. The liquid fraction may then be subjected to concentration, e.g. by evaporation, and, if necessary, the pH of the liquid fraction may be adj usted to 5 . 5 - 6 , e . g . with sodium hydroxide (NaOH) or potassium hydroxide (KOH) , to provide a crude liquid fraction . The separated crude liquid fraction may thus comprise 05 sugars from hydrolyzed hemicellulose as well as soluble l ignin and other by-products .

[0071] The fraction comprising solid cellulose particles may have a total dry matter content of 15 - 50 weight-% . The fraction comprising solid cellulose particles may, in addition to cellulose , comprise lignin . As the C5 sugars are ef ficiently removed with the crude liquid fraction, the fraction comprising solid cellulose particles may comprise carbohydrates such as solid C6 sugars . The fraction comprising solid cellulose particles may also comprise other carbohydrates and other components . The fraction comprising solid cellulose particles may also comprise an amount of C5 sugars .

[0072] The separated and recovered fraction comprising solid cellulose particles may be further puri fied or washed before being subj ected to enzymatic hydrolysis at 124 .

[0073] The main process stream, i . e . the biomass- derived feedstock, may then continue into enzymatic hydrolysis 124 , where the aim is to convert polysaccharides into C6 monomers , essentially converting cellulose into glucose . Lignin and other remaining solids are removed after the enzymatic hydrolysis , and the obtained C6 sugars are fed further to a sugar-to- chemical phase 103 . The removed lignin may be utili zed further in other processes .

[0074] The subsequent utili zation of the sugars in the sugar-to-chemical phase 103 may comprise steps such as puri fication 131 of the sugars ( C5 and / or C6 carbohydrates ) and one or more sugar conversion processes 132 . The sugar conversion processes 132 may include processes such as catalytical hydrotreatment to produce glycols .

[0075] As a skilled person will understand, one or more of the phases , stages and / or steps illustrated in the proces s o f Fig . 1 may be omitted depending e . g . on the biomass , or additional stages and / or steps may be included as desired .

[0076] Figure 2 illustrates in more detail an example o f what may be included in the part of the process that in Fig . 1 was only represented by the enzymatic hydrolysis at 124 . The process stream that comes from the pretreatment part has the form of a water-based slurry . It contains mainly cellulose , but also small amounts of hemicellulose . One purpose of the preceding pretreatment part was to remove hemicellulose and 05 sugars , but some always remains . The enzymatic hydrolysis step is mainly designed to convert the cellulose into monomeric carbohydrates ( C6 carbohydrates ) , but at the same time it also serves to convert the small remaining fraction of hemicellulose into respective monomeric carbohydrates ( 05 carbohydrates ) .

[0077] The slurry may be subj ected to pH control , after which it may go into a prehydrolysis 201 , typically a short one , in which selected enzymes are added . The prehydrolysis 201 may be performed e . g . as a continuous process .

[0078] The prehydrolysed slurry may then serve as the biomass-derived feedstock that then proceeds to a first hydrolysis step 202 . The subsequent first hydrolysis step 202 may be performed in batches or as a continuous process . Preferably it may be performed in batches , so that the conditions and proceeding of the hydrolysis reaction can be monitored and controlled .

[0079] A filtrate from the first solid / liquid separation step 203 following the first hydrolysis step 202 separates a part of the soluble C6 carbohydrates already, while the solid fraction is taken to re- slurrying 204 and further to an additional ( second) hydrolysis step 205 as the biomass-derived feedstock .

[0080] In the context of this speci fication, reslurrying may refer to a method step ( and the corresponding processing equipment ) in which a processed product is suspended in water or an aqueous solution . In a process such as those described here , reslurrying is frequently used after solid / liquid separation, in order to make the separated solid fraction easier to handle and al so in order to further clean it from any remaining soluble compounds in a subsequent further solid / liquid separation step .

[0081] The output from the second enzymatic hydrolysi s step 205 i s conveyed to a second solid / liquid separation step 206 , in which a liquid fraction comprising C 6 carbohydrates and a solid fraction are separated from each other . There may be consecutive rounds of solid / liquid separation and re-slurrying, and the number o f such consecutive rounds may vary . The separated lignin is a product of the solid / liquid separation step 206 .

[0082] The success ful conversion from glucan in the prehydrolysis 201 and hydrolysi s steps 202 and 205 may be highly important to the ef ficient production of C6 carbohydrates . Factors that af fect the ef ficiency of the hydrolysis include - but are not limited to - the following : the extent to which the preceding pretreatment and hemihydrolysis achieve their desired results ; the selection and dosing of the enzyme ( s ) ; the pH and temperature of the slurry in which the hydrolysis takes place ; the ef ficiency of mixing the slurry during the reaction period; the possible presence and constitution of chemical inhibitors like organic acids or furans ; the possible presence and nature of microbial contamination; and even the tree species or other nature of the original source of raw material . While the ef fect of many such factors can be predicted at least to some extent and acted upon, it would be highly beneficial to be able to monitor in real time ( or, at least , with as short a delay as possible ) how the conversion proceeds . What is here said about the conversion of cellulose into C6 carbohydrates may apply also to the conversion of hemicellulose into C5 carbohydrates : the conversion reactions may behave in a suitably similar manner, so that actions taken to optimi ze the conversion of cellulose into C6 carbohydrates are likely to have an advantageous ef fect also for the conversion of ( the small amount of ) hemicellulose into C5 carbohydrates . The dosing of the at least one enzyme is an important factor ; it is also a maj or factor af fecting the costs of the process , because the enzymes used are typically costly . It may be beneficial i f a desired conversion can be achieved without overdosing the at least one enzyme .

[0083] The present method and arrangement may thus be used in any one o f the in the prehydrolysis 201 and hydrolysi s steps 202 and 205 ; in both hydrolysi s steps 202 and 205 ; or in all of the prehydrolysis 201 and hydrolysis steps 202 and 205 .

[0084] Figure 3 illustrates schematically a method and arrangement 301 for controlling enzymatic hydrolysis of a biomass-derived feedstock 302 in a manufacturing process of a chemical bioproduct . The arrangement 301 comprises a reactor 303 for subj ecting the biomass-derived feedstock 302 to enzymatic hydrolysis . In this exemplary embodiment the reactor 303 is a batch reactor, although a continuous reactor and continuous hydrolysis could also be contemplated .

[0085] The enzymatic hydrolysis takes place in a hydrolysis reaction mixture 304 contained in the reactor 303 . Thus at least one enzyme 305 is added to the reactor 303 and into the hydrolysis reaction mixture 304 . The hydrolysis reaction mixture 304 comprises solid matter 306, illustrated schematically as solid particles. The content of the solid matter 306 may depend e.g. on the possible pretreatment of the biomass-derived feedstock 302, but the hydrolysis reaction mixture 304 may comprise e.g. at least about 3 % (w / w) , or about 3 - 17 % (w / w) of the solid matter 306. The solid matter 306 may comprise or be formed of e.g. solid lignin particles, solid cellulose particles, and / or solid hemicellulose particles.

[0086] The hydrolysis reaction mixture 304 may be stirred during the enzymatic hydrolysis. The arrangement and / or the reactor 303 may thus further comprise e.g. means 307 for stirring the hydrolysis reaction mixture 304, such as a mixing device, for example an impeller. Such means 307 may create sufficient turbulence of the hydrolysis reaction mixture 304 during the enzymatic hydrolysis.

[0087] Temperature may be controlled in the reactor 303. To this end, the reactor 303 and / or the arrangement 301 may further comprise means for controlling the temperature in the reactor 303, for example a heat exchanger (not shown) .

[0088] The reactor 303 may further comprise an outlet 308, via which output 309 of the enzymatic hydrolysis obtained from the hydrolysis reaction mixture 304 may be conveyed further after the enzymatic hydrolysis has been completed to a desired extent. The output 309 of the enzymatic hydrolysis containing the obtained C6 sugars may then be conveyed further, e.g. to a solid / liquid separation step.

[0089] The arrangement 301 may further comprise a Brix measurement apparatus 310 configured to perform at least one Brix measurement, or the plurality of the Brix measurements, or the Brix measurements performed continuously on the hydrolysis reaction mixture 304. The Brix measurement apparatus 310 may comprise e.g. a refractometer. Using the Brix measurement apparatus 310 , the at least one Brix measurement , or the plurality of Brix measurements , or the Brix measurements performed continuously, may be performed on the hydrolysis reaction mixture 304 .

[0090] The at least one Brix measurement , or the plurality of the Brix measurements , or the Brix measurements performed continuously, may be done directly on the hydrolysis reaction mixture 304 in which the enzymatic hydrolysis is currently taking place . For example , the reactor 303 may contain a built-in measurement head as the Brix measurement apparatus 310 for the at least one Brix measurement , or the plurality o f the Brix measurements , or the Brix measuremeents performed continuously . The measurement head may e . g . protrude into the reactor 303 from an inside wall of the reactor 303 , for example on the side of the reactor 303 . I f there is a mixing device 307 in the reactor 303 , the built-in measurement head may be located in a position in the vicinity of the mixing device 307 , as illustrated in Fig . 3 . The Brix measurement apparatus 310 and / or the measurement head thereof may thus be arranged in the mixing zone of the reactor 303 , or in a position in which the hydrolysis reaction mixture 304 is in movement ( or configured to be in movement ) . For example , the Brix measurement apparatus 310 and / or the measurement head thereof may be arranged at a distance from the bottom of the reactor 303 , wherein the distance is about 10 - 50 % , preferably 20 - 40 % , of the height of the reactor 303 .

[0091] Other alternative or additional locations for the Brix measurement apparatus 310 may be contemplated . For example , a second Brix measurement apparatus 310 ' may be arranged within or near the outlet 308 of the reactor 303 . Thus , with the second Brix measurement apparatus 310 ' , the at least one Brix measurement may performed immediately downstream of the reactor 303 . Alternatively, the at least one Brix measurement could be performed on the output of the enzymatic hydrolysis 309 containing the obtained C6 sugars before or after a solid / liquid separation step . As a further example , the reactor 303 may comprise a circulation loop 311 configured to circulate at least a part of the hydrolys is reaction mixture 304 from the reactor 303 and back thereto . A third Brix measurement apparatus 310 ' ’ may be arranged within the circulation loop, such that the at least one Brix measurement or the plurality of the Brix measurements , or the Brix measurements performed continuously, may be performed in the circulation loop 311 . As a skilled person wil l understand, the arrangement may comprise one , two or more of the Brix measurement apparatuses 310 , 310 ' , 310 ' ’ , and that they could be arranged at any one of the locations illustrated in Fig . 3 , or in any other suitable location .

[0092] The results obtained from the at least one Brix measurement , or the plurality of the Brix measurements , or the Brix measurements performed continuously, may thus indicate a content of one or more soluble carbohydrates in the hydrolysis reaction mixture 304 .

[0093] The arrangement 301 may further comprise a process controller 312 coupled to receive measurement results from the Brix measurement apparatus ( es ) 310 , 310 ' , 310 ' ’ ( as indicated by the arrow from the Brix measurement apparatus 310 to the process controller 312 ; arrows from the other Brix measurement apparatuses 310 ' , 310 ' ’ have been omitted for clarity) . The process controller 312 may be configured to control a dosing of the at least one enzyme 305 into the hydrolysis reaction mixture 304 at least partially based on the results received in order to af fect the conversion of cellulose and hemicellulose into monomeric carbohydrates in the hydrolysis reaction mixture 304.

[0094] The arrangement 301 may further comprise additional process equipment 313, 314 upstream (313) or downstream (314) of the reactor 303, for example a solid / liquid separation apparatus 314. Such additional process equipment may include e.g. process equipment for performing any one of the steps 201, 202, 203, 204, 205, 206 depicted in Fig. 2. Although one reactor 303 is illustrated in Fig. 3 for simplicity, the arrangement 301 may comprise two or more reactors .

[0095] The Brix measurement apparatus ( es ) 310, 310' , 310' ’ may be configured to perform a plurality of Brix measurements at a plurality of instants during the enzymatic hydrolysis, and / or to perform Brix measurements continuously or continually during the enzymatic hydrolysis.

[0096] The at least one Brix measurement, or the Brix measurements, may assist in deciding, whether more of the at least one enzyme 305 should be still added, or e.g. whether an enzyme combination should be tuned, for the batch of the biomass-derived feedstock 302 currently being hydrolysed in the hydrolysis reaction mixture 304.

[0097] It is not necessary, however, to have the at least one Brix measurement, or the plurality of the Brix measurements, or the Brix measurements performed continuously, directed to the actual contents of the hydrolysis reaction mixture 304 to make decisions about the dosing of the at least one enzyme. In other words, controlling the dosing of the at least one enzyme does not need to be based on the at least one Brix measurement, or the plurality of the Brix measurements, or the Brix measurements performed continuously, shown in Fig. 3. Similar decisions may be made regarding a subsequent batch based on the results that were obtained from a previous batch, for example with at least one Brix measurement , or the plurality o f the Brix measurements , or the Brix measurements performed continuously in Fig . 3 .

[0098] The method may involve utilizing arti ficial intelligence or other machine-learning entity in making decisions concerning controlling the dosing of the at least one enzyme at least partially based on the results obtained from the at least one Brix measurement , or the Brix measurements . The process controller 312 may include a decision-making controller that may collect data on previously used values of the dosing of the at least one enzyme and the corresponding Brix measurement results and make conclusions about trends and interrelationships that might be di f ficult or impossible to perceive with only human intelligence . Such a decision-making controller that is arranged to utili ze arti ficial intelligence or other machinelearning entity may then develop further and extrapolate from initial , bas ic control algorithms to make decisions about process parameters that most optimally meet each available Brix measurement result of any future batch to be processed .

[0099] EXAMPLE 1

[0100] Wood chips were subj ected to hemihydrolysis us ing a dilute acid treatment and steam explosion . The biomass-derived feedstock thus obtained was washed and subj ected to enzymatic hydrolysis using a commercial cellulase mixture . After the washing, solid matter in the feedstock had an average particle si ze of 0 . 2 mm or less . A low enzyme dosing was used, and the the hydrolysis reaction mixture had an approx . 12 . 5 % dry matter content at the beginning of the enzymatic hydrolysis . pH was approx . 5 . 0 and temperature approx . 50 ° C during the hydrolysis . Two sets of Brix measurements were obtained at intervals during the enzymatic hydrolysis. A first set was obtained from samples obtained from the hydrolysis reaction mixture, from which solid matter was separated from the liquid, and Brix values were measured from the liquid using an ATAGO™ 3730 digital hand-held pen refractometer (referred to as "manual instrument") . A second set was obtained in-line, i.e. directly from the hydrolysis reaction mixture containing the solid matter, using a K-Patents Pharma Refractometer PR-23-AC for in-line concentration measurement (referred to as "in-line refractometer directly from slurry") .

[0101] Figure 4A illustrates the Brix values obtained for the two sets of Brix measurements. It was found that the Brix value at the starting point of the enzymatic hydrolysis was somewhat different with the two different Brix measurement apparatuses. One factor that may have affected the results may be that the inline refractometer measured the Brix values in the temperature of approx. 50 °C during the hydrolysis, while the manual instrument measured the Brix values at or near room temperature.

[0102] Figure 4B illustrates ABx, wherein the same two sets of Brix measurements were adjusted such that at 0 h, i.e. at the starting point of the the enzymatic hydrolysis, the Brix value was set to 0. As shown by Fig. 4B, the ABx, i.e. the rate of change of the Brix values, is very similar when using both Brix measurement apparatuses. This indicates that although the in-line refractometer was likely affected to some extent by the solid matter in the hydrolysis reaction mixture, very similar relative results were obtained by the two sets.

[0103] EXAMPLE 2 A second experiment was conducted in a similar manner as in Example 1 , except that a high enzyme dosing was used, and the the hydrolysis reaction mixture had an approx . 12 . 7 % dry matter content at the beginning of the enzymatic hydrolysis .

[0104] Figure 5A illustrates the Brix values obtained for the two sets of Brix measurements . Figure 5B illustrates ABx, i . e . the same two sets of Brix measurements adj usted such that at 0 h, i . e . at the starting point of the the enzymatic hydrolysis , the Brix value was set to 0 . Whi le not to be bound by theory, it may be that the content of solid matter was high at the beginning of the enzymatic hydrolysis and then decreased rapidly, as viscosity was found to decrease quite drastically during the first hour of the enzymatic hydrolysis . This may have af fected the ABx measured using the in-line refractometer . However, the ABx values were very comparable with both Brix measurement apparatuses . In particular, after the first hour , the changes in the Brix values were found to be very similar when using both Brix measurement apparatuses . Therefore , the ABx values were found to be highly indicative of the content of soluble carbohydrates in the hydrolysis reaction mixture and the conversion of cellulose into monomeric carbohydrates .

[0105] It is obvious to a person skil led in the art that with the advancement of technology, the basic idea may be implemented in various ways . The embodiments are thus not limited to the examples described above ; instead they may vary within the scope of the claims .

[0106] The embodiments described hereinbefore may be used in any combination with each other . Several of the embodiments may be combined together to form a further embodiment. A method, a product, an arrangement, or a use, disclosed herein, may comprise at least one of the embodiments described hereinbefore. It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item refers to one or more of those items. The term "comprising" or "including" is used in this specification to mean including the feature (s) or act(s) followed thereafter, without excluding the presence of one or more additional features or acts.

Claims

CLAIMS1 . A method for control ling enzymatic hydrolysis of a biomass-derived feedstock in a manufacturing process of a chemical bioproduct , wherein the enzymatic hydrolysis takes place in a hydrolysis reaction mixture , and wherein the hydrolysis reaction mixture comprises solid matter ; wherein the method comprises performing at least one Brix measurement on the hydrolysis reaction mixture ; and controlling a dosing of at least one enzyme into the hydrolysis reaction mixture at least partially based on the results obtained from the at least one Brix measurement ; wherein the results indicate a content o f one or more soluble carbohydrates in the hydrolysis reaction mixture , and wherein the controlling of the dosing of the at least one enzyme into the hydrolysis reaction mixture is performed in order to af fect at least the conversion of cellulose and optionally hemicellulose into monomeric carbohydrates in the hydrolysis reaction mixture .2 . The method according to claim 1 , wherein the method comprises performing the at least one Brix measurement directly on the hydrolysis reaction mixture in which the enzymatic hydrolysis is currently taking place .3 . The method according to claim 1 or 2 , wherein the at least one Brix measurement is performed using a refractometer .4 . The method according to any one of claims 1 - 3 , wherein the enzymatic hydrolysi s takes place in the hydrolysis reaction mixture in a reactor containing the hydrolysis reaction mixture , and the at least one Brix measurement is performed in the reactor or immediately downstream thereof , and / or in acirculation loop circulating the hydrolysis reaction mixture from the reactor and back thereto.

5. The method according to any one of claims 1 - 4, wherein the hydrolysis reaction mixture comprises at least about 3 % (w / w) , or about 3 - 17 % (w / w) of the solid matter; preferably at least about 5 % (w / w) , or about 5 - 16 % (w / w) of the solid matter; more preferably, at least about 7 % (w / w) , or about 7 - 15 % (w / w) of the solid matter.

6. The method according to any one of claims 1 - 5, wherein the solid matter comprises lignin, solid cellulose particles, and / or hemicellulose.

7. The method according to any one of claims 1 - 6, wherein the method comprises performing a plurality of Brix measurements on the hydrolysis reaction mixture at a plurality of instants during the enzymatic hydrolysis.

8. The method according to any one of claims 1 - 7, wherein the method comprises performing Brix measurements on the hydrolysis reaction mixture continuously during the enzymatic hydrolysis.

9. The method according to any one of claims 1 - 8, wherein the biomass-derived feedstock comprises or is feedstock derived from pretreated wood particles; and / or wherein the solid matter in the biomass-derived feedstock has an average particle size of 0.2 mm or less.

10. The method according to any one of claims 1 - 9, wherein the enzymatic hydrolysis is performed in batches or as a continuous process.

11. The method according to any one of claims 1 - 10, wherein the temperature of the hydrolysis reaction mixture is in the range of about 40 - 55 °C, preferably in the range of about 45 - 55 °C, more preferably in the range of about 50 - 55 °C.

12. An arrangement for controlling enzymatic hydrolysis of biomass-derived feedstock in amanufacturing process of a chemical bioproduct , wherein the arrangement comprises at least one reactor for subj ecting the biomass-derived feedstock to enzymatic hydrolysis , the enzymatic hydrolysis taking place in a hydrolysis reaction mixture contained in the at least one reactor, wherein the hydrolysis reaction mixture comprises solid matter, additional process equipment upstream and downstream of the at least one reactor in the process , a Brix measurement apparatus configured to perform at least one Brix measurement on the hydrolysis reaction mixture , and a process controller coupled to receive measurement results from the Brix measurement apparatus , wherein said process controller is configured to control a dosing of at least one enzyme into the hydrolysis reaction mixture at least partially based on the results received in order to af fect the conversion of cellulose and hemicellulose into monomeric carbohydrates in the hydrolysis reaction mixture .13 . The arrangement according to claim 12 , wherein the Brix measurement apparatus is configured to perform the at least one Brix measurement directly on the hydrolysis reaction mixture in which the enzymatic hydrolysis is currently taking place .14 . The arrangement according to claim 12 or 13 , wherein the Brix measurement apparatus comprises or is a refractometer .15 . The arrangement according to any one of claims 12 - 14 , wherein the Brix measurement apparatus is configured to perform the at least one Brix measurement on the hydrolysis reaction mixture in the reactor or immediately downstream thereof , and / or wherein the at least one reactor comprises acirculation loop configured to circulate the hydrolysis reaction mixture from the reactor and back thereto , and the Brix measurement apparatus is configured to perform the at least one Brix measurement on the hydrolysis reaction mixture in the circulation loop .16 . The arrangement according to any one of claims 12 - 15 , wherein the Brix measurement apparatus is configured to perform Brix measurements on the hydrolysis reaction mixture continuously during the enzymatic hydrolysis .

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