WO2012160255A1

WO2012160255A1 - Method and apparatus for manufacturing a hydroxycarboxylic acid product and use of bleaching filtrate

Info

Publication number: WO2012160255A1
Application number: PCT/FI2012/050481
Authority: WO
Inventors: Matti Ristolainen; Jutta Nuortila-Jokinen; Esa Hassinen; Kati Eskelinen
Original assignee: Upm-Kymmene Corporation
Priority date: 2011-05-23
Filing date: 2012-05-22
Publication date: 2012-11-29
Also published as: FI20115496A; UY34085A; FI20115496A0

Abstract

The invention relates to a method and an apparatus for manufacturing a hydroxycarboxylic acid product from lignocellulose-based raw material. According to the invention,a first effluent (2) used as a raw material is concentrated to provide a concentrate (3), the concentrate (3) is treated by a hydrolysis (11) to form saccharides (4), the saccharides (4) are fermented (12) to form hydroxycarboxylic acid, and the pH of the fermentation (12) is controlled by using a second effluent (16), for forming a hydroxycarboxylic acid product. Further, the invention relates to use of a bleaching filtrate.

Description

METHOD AND APPARATUS FOR MANUFACTURING A HYDROXYCARBOXYLIC ACID PRODUCT AND USE OF BLEACHING FILTRATE FIELD OF THE INVENTION

The invention relates to the method as de^¬ fined in the preamble of claim 1 and to the apparatus as defined in the preamble of claim 16 for manufactur^¬ ing a hydroxycarboxylic acid product from lignocellu- lose-based material. Further, the invention relates to the use of a bleaching filtrate as defined in the claim 27.

BACKGROUND OF THE INVENTION

Hydroxycarboxylic acid based products, e.g. lactic acid, are manufactured from different kinds of lignocellulose-based raw stock, e.g. from waste wa^¬ ters, residue flows and sludges derived from paper and/or pulp mill. The waste waters contain organic ma- terial such as fibers and traces of bleaching agents. The process of hydroxycarboxylic acid production is usually based on enzymatic hydrolysis and fermenta^¬ tion. The produced hydroxycarboxylic acid is separated for example by crystallization.

From JP 59014792 is known a method for preparing citric acid. The citric acid is prepared by culturing micro-organism capable of producing citric acid, in a medium containing a sugar obtained from the waste liquid of SP pulp as a carbon source. From JP 59115795 is known a method in which the sulfite pulp waste liquid is concentrated with an ultrafilter and resulting liquid is further concentrated by a vacuum evaporator and is then burned in a recovery boiler. From WO 9919290 is known a process for the production of lactic acid products from mixture containing free lactic acid and dissolved lactate salt. Preferred mix^¬ tures for processing are obtained from fermentation broths, preferably from fermentation processes con^¬ ducted at a pH of 4.8 or lower. From WO 00/56693 is known a method for purificating lactic acid by distil^¬ lation and crystallization.

OBJECTIVE OF THE INVENTION

The objective of the invention is to dis- close a new type of a method and apparatus for manu^¬ facturing a hydroxycarboxylic acid product. Further, an objective of the invention is to disclose the use of a bleaching filtrate as a pH-controlling agent. SUMMARY OF THE INVENTION

The method for manufacturing a hydroxycarbox^¬ ylic acid product according to the present invention is characterized by what is presented in claim 1.

The apparatus for manufacturing a hydroxycar- boxylix acid product according to the present inven^¬ tion is characterized by what is presented in claim 16.

The use of a bleaching filtrate according to the present invention is characterized by what is pre- sented in claim 27.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are included to provide a further understanding of the invention and constitutes a part of this specification, illus^¬ trate some embodiments of the invention and together with the description help to explain the principles of the invention. In the figures:

Fig. 1 is a flow chart illustration of a method and an apparatus according to one embodiment of the present invention, and Fig. 2 is a flow chart illustration of a method and an apparatus according to another embodi^¬ ment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

The invention is based on a method for manu^¬ facturing a hydroxycarboxylic acid product 7 from lig- nocellulose-based raw material. According to the inven^¬ tion a first effluent 2 used as a raw material is con- centrated 10 to provide a concentrate 3, the concen^¬ trate is treated by a hydrolysis 11 to form saccha^¬ rides, preferably monosaccharides, the saccharides 4 are fermented 12 to form hydroxycarboxylic acid, and the pH of the fermentation 12 is controlled 18 a-c by using a second effluent 16, and a hydroxycarboxylic acid product 7 is formed of hydroxycarboxylic acid.

Further, the invention is based on an apparatus for manufacturing a hydroxycarboxylic acid prod^¬ uct from lignocellulose-based raw material. According to the invention, the apparatus for forming hydroxycarboxylic acid product includes an effluent feeding means 20 for feeding a first effluent 2 used as a raw material to the apparatus; a first concentra^¬ tion device 10 for concentrating the first effluent to provide a concentrate 3; a hydrolysis and fermentation unit 11, 12, 21 for treating the concentrate 3 by hy^¬ drolysis 11 to form saccharides 4 and for fermenting 12 the saccharides 4 to form hydroxycarboxylic acid; and a pH controlling means 18a-c for controlling the pH of the fermentation 12 by using a second effluent 16.

Further, the invention is based on use of a bleaching filtrate in controlling the pH of hydrolysis and/or fermentation of a pulp mill effluent in hy- droxycarboxylic acid product manufacturing. Lignocellulose means in this connection a ma^¬ terial formed from cellulose, hemicellulose and lig- nin. Lignocellulose-based material means in this con^¬ nection any material containing cellulose and/or hemi- cellulose, which may also contain, in addition to cel^¬ lulose and hemicellulose, lignin, starch and/or other substances .

In this connection, the term "effluent" means any effluent selected from the group of pulp mill ef- fluent, paper mill effluent, saw mill effluent, food manufacturing effluent, brewing industry effluent and their combinations. The effluent comprises alkaline and/or acidic waste waters, filtrates and residual wa^¬ ters of the process. The effluent contains, at least in some quantity, the lignocellulosic material de^¬ scribed above. The effluent can includes one or more than one component .

In one embodiment the first effluent is com^¬ ing from a pulp mill. In one embodiment the first ef- fluent is a waste water, waste sludge or residue flow from the pulp mill. In one embodiment the first efflu^¬ ent is a waste water. In one embodiment the first ef^¬ fluent can include alkaline and/or acid components, e.g. a bleaching filtrate, and/or any residue effluent which comes from the pulp mill. In one embodiment the first effluent is an alkaline bleaching filtrate. The first effluent, used as raw stock in the process ac^¬ cording to the invention, can also contain, in addition the effluent, other subtances.

In one embodiment the second effluent is com^¬ ing from a pulp mill. In one embodiment the second ef^¬ fluent can be an alkaline and/or acid effluent, e.g. a bleaching filtrate, which comes from the pulp mill.

In one embodiment the first effluent is sub- stantially same material than the second effluent. In one embodiment the first effluent is partly same mate^¬ rial than the second effluent.

A saccharide means in this connection any frac^¬ tion mainly based on monosaccharides. The saccharides may contain disaccharides and/or oligosaccharides. In one preferred embodiment, the disaccharides and oligo^¬ saccharides are mainly disintegrated to monosaccharides in the process according to the invention.

In one embodiment the pH is controlled during the fermentation 12 by the second effluent 16. In one embodiment of the invention the pH is controlled, and preferably adjusted, during the fermentation by the second effluent, preferably alkaline and/or acid bleaching filtrate from the pulp mill. In one embodi- ment the pH is controlled by the alkaline bleaching fil^¬ trate from the pulp mill.

In one embodiment, the bacteria survive at pH 4 - 8 in the fermentation, more preferably at pH 5 - 7. In one embodiment the temperature in the fermenta- tion is set between 30 and 80°C. In one embodiment, yeast, bacteria, microbes, nutrients or their mixtures are fed to the suspension in connection with fermentation to promote the fermentation. In one embodiment of the invention, at least one enzyme is added to the sus- pension in connection with fermentation.

In one embodiment the pH of the first effluent is controlled, preferably for neutralizing the acidic substances of the first effluent, before hydrolysis 11 and/or fermentation 12 by the second effluent 16. In one embodiment the pH of the first effluent is adjusted suitable for enzymatic hydrolysis and/or fermentation by using a second effluent with alkaline or acid composi^¬ tion, e.g. by an effluent from the pulp mill such as a bleaching filtrate from the pulp mill.

The use of the alkaline bleaching filtrate as the second effluent in the pH controlling gives the ad- vantage that the hydrogen peroxide residues in the fil^¬ trate kill all the unwanted bacteria in the first efflu^¬ ent. In one embodiment the killing the unwanted bacteria requires sufficient dwelling time. In the enzymatic hy- drolysis, the new hydrolyzing bacteria are added and there are no competing bacteria, since they have been destroyed by the hydrogen peroxide in the second efflu^¬ ent. In addition, the alkaline bleach filtrate contains a lot of carbohydrates, which increase the yield of fer- mentation.

In one embodiment of the invention, water 17 is removed 10 from the first effluent 2, e.g. from the first pulp mill effluent, to provide a concentrate 3. In one embodiment water is removed from the first ef- fluent to provide a concentrate so as to have in the first effluent a percentage of solids of approximately 1 to 2% after removal of water.

In one embodiment of the invention the first effluent 2, e.g. the first pulp mill effluent, is fil- tered 10 to provide a concentrate 3. In one embodiment the first effluent is filtered by an ultrafiltration. In one embodiment the first effluent is filtered by a nanofiltration . In one embodiment a concenrate may be formed by any concentration method or device, e.g. evap- orating or separating. In a preferred embodiment also organic substances are separated simultaneously.

In one embodiment of the invention the hydrol^¬ ysis 11 is selected from the group of acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis and their combinations.

In one embodiment, the concentrate is treated by enzymatic hydrolysis. In one embodiment, the feeding of enzymes is phased so that the required amount of en^¬ zymes to achieve optimal hydrolysis is fed in a phased manner to the hydrolysis. In the phasing, the properties of different enzyme components are taken into account so that preferably different enzyme mixtures are fed to the hydrolysis .

In a preferred embodiment, the enzymes as well as the enzyme mixtures formed from them are selected to hydrolysis and fermentation depending on the product fractions to be obtained. The enzyme mixtures may con^¬ tain enzymes of one or more groups. Any enzymes known per se and suitable for the purpose can be used as the enzymes .

In this invention, a hydroxycarboxylic acid can include at least one hydroxycarboxylic acid or combina^¬ tion of different hydroxycarboxylic acids. In this con^¬ nection, hydroxycarboxylic acid means any hydroxycar^¬ boxylic acid. In this connection, a hydroxycarboxylic acid product can include any hydroxycarboxylic acid or combination of different hydroxycarboxylic acids.

In one embodiment of the invention hydroxycarboxylic acid product 7 is selected from the group of glycolic acid, 3-hydroxypropanoic acid, lactic acid, succinic acid, xyloisosaccharine acid, anhydroisosac- charine acid, 3, 4-dihydroxybutyric acid, 4- hydroxybutyric acid, glyceric acid, maleic acid, cit^¬ ric acid, oxalic acid and their combinations. Prefera^¬ bly, hydroxycarboxylic acid product is selected from hydroxyl carboxylic acids formed from carbohydrate ma^¬ terials .

In one embodiment of the invention the hydrol^¬ ysis 11 and fermentation 12 are carried out at the same process stage 21. In one embodiment, in which an entzymatic hydrolysis is used in the hydrolysis step, the hydrolysis and fermentation are accomplished in one hydrolysis and fermentation process step. In one embodi^¬ ment, the fermentation is continuous process. In one em^¬ bodiment, batch fermentation is used.

In one embodiment the hydrolysis and fermen^¬ tation unit 21 comprises a hydrolysis device 11 and and a fermentation device 12. In one embodiment the hy^¬ drolysis device and fermentation device are separate devices .

In one embodiment, after the fermentation a suspension 5a containing the hydroxycarboxylic acid from the fermentation is concentrated 15 to form the hydroxycarboxylic acid product 7. In one embodiment the apparatus includes a second concentration device 15 for concentrating a suspension 5a containing the hydroxycarboxylic acid to form the hydroxycarboxylic acid product 7.

In one embodiment of the invention after the fermentation 12 the suspension 5a containing the hydroxycarboxylic acid is filtered 14 for separating fermentation residue 6 from the hydroxycarboxylic acid suspension 5b. In one embodiment lignin is separated by the filtering from the hydroxycarboxylic acid sus^¬ pension. In one embodiment the fermentation residue is treated by an anaerobic treatment, burning and/or lig- nin purification.

In one embodiment, after the fermentation the suspension 5b containing the hydroxycarboxylic acid is concentrated 15 and the hydroxycarboxylic acid is sepa^¬ rated. The concentration 15 can be made by any concen- tration process or apparatus known per se and suitable to be used in concentration. In a preferred embodiment, simultaneously hydroxycarboxylic acid is purified.

In one embodiment, after the fermentation the suspension containing the hydroxycarboxylic acid is con- centrated by crystallization. In one embodiment after the fermentation the suspension containing the hydroxycarboxylic acid is concentrated by suspension melt crystallization. In one embodiment the suspension melt crystallization is a two-stage crystallization in which the first stage is water crystallization and the second stage is hydroxycarboxylic acid crystalliza^¬ tion.

The apparatus includes pH controlling means. In one embodiment pH controlling means 18a-c are arranged to control the pH during the fermentation 12 of the sac^¬ charides. In one embodiment pH controlling means 18a-c are arranged to control the pH of the first effluent 2,3 and to neutralize acidic substances of the first effluent before the hydrolysis 11 and/or fermentation 12.

In one embodiment of the invention the appa^¬ ratus includes a dewaterer 10 for removing water 17 from the first effluent to provide a concentrate. In one em^¬ bodiment the apparatus includes a first filtering device for filtering the first effluent to provide a concen^¬ trate. The first filtering device can be any filtering device known per se and suitable for the purpose can be used in the filtering of the effluent.

In one embodiment of the invention the appa- ratus includes a second filtering device 14 for filter^¬ ing the suspension 5a containing the hydroxycarboxylic acid after the fermentation to separate lignin and fermentation residue 6 from the hydroxycarboxylic acid suspension 5b. The second filtering device can be any filtering device known per se and suitable for the pur^¬ pose can be used in the filtering of the suspension.

In one embodiment of the invention the second concentration device 15 is a suspension melt crystalli^¬ zation device. The second concentration device can be any concentration device known per se and suitable for the purpose can be used in the concentration of the sus^¬ pension .

In hydrolysis and fermentation, any hydrolysis or fermentation process or device known per se and suit- able for the purpose can be used. In one embodiment, the concentrated hydroxycar- boxylic acid product formed by fermenting is used as such. In another embodiment, the concentrated hy- droxycarboxylic acid product is processed further to produce a desired product. In one embodiment of the in^¬ vention the hydroxycarboxylic acid product is used as chemical, biochemical and/or polymer component.

By the method and apparatus according to the invention, it is possible to utilize different kinds of pulp mill effluents which have not been utilized cost-effectively before to form valuable products.

In the invention the second effluent is used as an adjust chemical in the pH controlling of the fermentation. The second effluent includes carbohy- drates, which are simultaneously a raw stock of the hydrolysis. The use of the alkaline bleaching filtrate as the second effluent in the pH controlling gives the technical effect that the hydrogen peroxide residues in the filtrate kill all the unwanted bacteria in the first effluent.

By the invention, a good product yield is provided .

By the invention, products are provided cost- effectively and with low production costs.

EXAMPLES

In the following, the invention will be described in more detail by means of detailed exemplary embodiment with reference to the accompanying figures.

Example 1

Fig. 1 shows an apparatus for producing lactic acid which is used for producing lactic acid by the process according to the invention.

The apparatus of Fig. 1 includes an effluent feeding means 20 for feeding an effluent used as a raw stock 2 from a pulp mill 1. The effluent feeding means 20 comprises a pipe or a duct for transporting the ef^¬ fluent. The effluent feeding means may also comprise pump(s) or any other equipment needed for feeding the effluent from the pulp mill to an ultrafiltration device 10. The apparatus includes an ultrafiltration device 10 for removing water 17 from the raw stock 2 and for concentrating the raw stock to provide a concentrate 3. Furthermore, the process includes a hydrolysis device 11 based on an acid hydrolysis or alkaline hydrolysis for hydrolyzing the concentrate 3 to form saccharides 4, and a fermentation device 12 for fermentating the saccharides 4 to form lactic acid. The apparatus includes a pH controlling means 18 a-c for controlling and adjusting the pH of the fermentation 12 by using a second efflu^¬ ent 16 from the pulp mill 1. Before the hydrolysis 11 the concentrate 3 can be treated in a dwell tank 13, es^¬ pecially if a bleaching filtrate is used as the second effluent. The second effluent can be fed in the dwell tank 13 and/or in the fermentation 12. The pH controlling means comprises at least one measuring device 18a for measuring the pH in the fermentation 12 and/or before the hydrolysis 11, a feeding device 18c for feeding the second effluent and a control unit 18b for control^¬ ling and adjusting the feeding of the second effluent on grounds of the pH measurements. The feeding device is pump or any other suitable equipment for feeding the second effluent from the pulp mill to the dwell tank 13 and/or the fermentation device 12. The control unit 18b contains reception means to receive signals from the measuring devices 18a, calculation means to form control signals, and control signal transmitting means to trans^¬ mit the control signals formed in the control unit to the feeding device 18c.

After the fermentation a suspension 5a including lactic acid is led to a filtering device 14, where lignin and fermentation waste 6 is filtrated from a fermentation mother liquid 5b including lactic acid. The fermentation mother liquid 5b including lactic acid is concentrated in a concentration device 15 to form con- centrated lactid acid 7. The concentration device 15 is a suspension melt crystallization process where water is removed from the fermentation mother liquid 5b including lactic acid, and lactic acid 7 is separated from the fermentation mother liquid 9 for forming lactic acid 7 with concentration over 90 %. Water 8 from the concentration device 15 is led to the pulp mill 1. The fermen^¬ tation mother liquid 9 is recirculated into the suspen^¬ sion 5a after the fermentation 12.

In this example a pulp mill bleaching fil- trate is used as a raw stock. Water is removed from the raw stock to provide a concentrate with a high percentage of solids, preferably a percentage of sol^¬ ids of 1% to 2%. The concentrate is fed to a hydrolysis step. Preferably an acidic second effluent from the pulp mill can be added into the raw stock before the hydroly^¬ sis and/or during the fermentation.

The hydrolysis is carried out in a hydrolysis reactor at a temperature of 100 to 200°C. The duration of the hydrolysis is preferably approximately 0.5 - 2 hour. Saccharides, mainly monosaccharides, are formed in the hydrolysis.

After the hydrolysis, the saccharides are sup^¬ plied to fermentation where the temperature is prefera^¬ bly approximately 30 - 55°C, and the duration is approx- imately 24 - 60 hours. In fermentation, lactic acid is formed from the saccharides. The pH of the fermentation is controlled and adjusted by using the second effluent from the pulp mill. The bacteria can be added in the fermentation, preferably after neutralization after the hydrolysis. After fermentation, the suspension including lactic acid is filtrated for separating lignin and fer^¬ mentation waste from the fermentation mother liquid including lactic acid. Separated lignin and fermantion waste can be further processed e.g. in anaerobic fermen^¬ tation, by burning or in lignin purification. The fermentation mother liquid including lactic acid is concentrated by a suspension melt crystallisation for forming a concentrated lactic acid.

Example 2

Fig. 2 shows an apparatus for producing lactic acid which is used for producing lactic acid by the process according to the invention.

The apparatus of Fig. 2 includes an effluent feeding means 20 for feeding an effluent used as a raw stock 2 from a pulp mill 1. The effluent feeding means 20 comprises a pipe or a duct for transporting the ef^¬ fluent. The effluent feeding means may also comprise pump(s) or any other equipment needed for feeding the effluent from the pulp mill to an ultrafiltration device 10. The apparatus includes an ultrafiltration device 10 for removing water 17 from the raw stock 2 and for concentrating the raw stock to provide a concentrate 3. Furthermore, the process includes an entzymatic hydroly^¬ sis and fermentation unit 21 for hydrolyzing the concentrate 3 to form saccharides and for fermentating the saccharides to form lactic acid. In this unit 21 hydrol^¬ ysis 11 and fermentation 12 are accomplished in one hy- drolysis and fermentation process stage. The apparatus includes a pH controlling means 18 a-c for controlling and adjusting the pH of the fermentation 12 by using a second effluent 16 from the pulp mill 1. Before the hy^¬ drolysis 11 the concentrate 3 can be treated in a dwell tank 13, especially if a bleaching filtrate is used as the second effluent. The second effluent can be fed in the dwell tank 13 and/or in the fermentation 12. The entzymes are mixed with the concentrate 3 in the hydrol^¬ ysis step 11. The pH controlling means comprises at least one measuring device 18a for measuring the pH in the fermentation step 12 and/or before the hydrolysis step 11, a feeding device 18c for feeding the second ef^¬ fluent and a control unit 18b for controlling and ad^¬ justing the feeding of the second effluent on grounds of the pH measurements. The feeding device is pump or any other suitable equipment for feeding the second effluent from the pulp mill to the dwell tank 13 and/or the fer^¬ mentation step 12. The control unit 18b contains recep^¬ tion means to receive signals from the measuring devices 18a, calculation means to form control signals, and con- trol signal transmitting means to transmit the control signals formed in the control unit to the feeding device 18c.

After the fermentation a suspension 5a including lactic acid is led to a filtering device 14, where lignin and fermentation waste 6 is filtrated from a fermentation mother liquid 5b including lactic acid. The fermentation mother liquid 5b including lactic acid is concentrated in a concentration device 15 to form con^¬ centrated lactid acid 7. The concentration device 15 is a suspension melt crystallization process where water is removed from the fermentation mother liquid 5b including lactic acid, and lactic acid 7 is separated from the fermentation mother liquid 9 for forming lactic acid 7 with concentration over 90 %. Water 8 from the concen- tration device 15 is led to the pulp mill 1. The fermen^¬ tation mother liquid 9 is recirculated into the suspen^¬ sion 5a after the fermentation 12.

In this example a pulp mill bleaching filtrate is used as a raw stock. Water is removed from the raw stock to provide a concentrate with a high percentage of solids, preferably a percentage of sol- ids of 1% to 2%. The concentrate is fed to an entzymatic hydrolysis and fermentation process stage. An acidic or alkaline second effluent from the pulp mill can be added into the raw stock before the entzymatic hydrolysis step and/or during the fermentation step.

The enzymes are mixed with the concentrate by powerful mixing in a hydrolysis step at a temperature of 30 to 65°C. The duration of the hydrolysis is preferably approximately 24 hours. Saccharides, mainly monosaccha^¬ rides, are formed in the hydrolysis. The saccharides are supplied to fermentation where the temperature is pref^¬ erably approximately 30 - 55°C, and the duration is ap^¬ proximately 24 - 60 hours. In fermentation, lactic acid is formed from the saccharides. The pH of the fermenta^¬ tion is controlled and adjusted by using an alkaline bleaching filtrate from the pulp mill. The bacteria can be added for the fermentation.

After hydrolysis and fermentation process stage, the suspension including lactic acid is filtrated for separating lignin and fermentation waste from the fermentation mother liquid including lactic acid. Separated lignin and fermantion waste can be further processed e.g. in anaerobic fermentation, by burning or in lignin purification. The fermentation mother liquid including lactic acid is concentrated by a suspension melt crystallisation for forming a concentrated lactic acid.

The method and the apparatus according to the invention are suitable as different embodiments to be used in the manufacture of most different hydroxycarbox- ylic acid products.

The invention is not limited merely to the examples referred to above; instead, many variations are possible within the scope of the inventive idea defined by the claims.

Claims

1. A method for manufacturing a hydroxycar- boxylic acid product from lignocellulose-based raw ma^¬ terial, c h a r a c t e r i z e d in that a first efflu- ent used as a raw material is concentrated to provide a concentrate, the concentrate is treated by a hydrol^¬ ysis to form saccharides, the saccharides are ferment^¬ ed to form hydroxycarboxylic acid, and the pH of the fermentation is controlled by using a second effluent.

2. The method according to claim 1, c h a r a c t e r i z e d in that the second effluent is alka^¬ line and/or acid bleaching filtrate from the pulp mill .

3. The method according to claim 1 or 2, c h a r a c t e r i z e d in that the pH is controlled during the fermentation by the second effluent.

4. The method according to any one of claims 1 to 3, c h a r a c t e r i z e d in that the pH of the first effluent is controlled before the hydrolysis and/or fermentation by the second effluent.

5. The method according to any one of claims 1 to 4, c h a r a c t e r i z e d in that water is removed from the first effluent to provide a concentrate.

6. The method according to any one of claims 1 to 5, c h a r a c t e r i z e d in that the first effluent is filtered to provide a concentrate.

7. The method according to any one of claims 1 to 6, c h a r a c t e r i z e d in that the first effluent is a waste water from the pulp mill.

8. The method according to any one of claims 1 to 7, c h a r a c t e r i z e d in that the hydrolysis and fermentation are carried out at the same process stage .

9. The method according to any one of claims 1 to 8, c h a r a c t e r i z e d in that the hydrolysis is selected from the group of acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis and their combina^¬ tions .

10. The method according to any one of claims 1 to 9, c h a r a c t e r i z e d in that hydroxycarbox- ylic acid product is selected from the group of gly- colic acid, 3-hydroxypropanoic acid, lactic acid, suc^¬ cinic acid, xyloisosaccharine acid, anhydroisosaccha- rine acid, 3, 4-dihydroxybutyric acid, 4-hydroxybutyric acid, glyceric acid, maleic acid, citric acid, oxalic acid and their combinations.

11. The method according to any one of claims 1 to 10, c h a r a c t e r i z e d in that after the fermentation a suspension containing the hydroxycarboxylic acid is concentrated to form the hydroxycar- boxylic acid product.

12. The method according to any one of claims

I to 11, c h a r a c t e r i z e d in that after the fermentation the suspension containing the hydroxycarboxylic acid is filtered for separating fermentation residue from the hydroxycarboxylic acid suspension.

13. The method according to claim 12, c h a r a c t e r i z e d in that the fermentation residue is treated by an anaerobic treatment, burning and/or lig- nin purification.

14. The method according to any one of claims

II to 13, c h a r a c t e r i z e d in that after the fer^¬ mentation the suspension containing the hydroxycarboxylic acid is concentrated and the hydroxybarboxylic acid is separated.

15. The method according to any one of claims

1 to 14, c h a r a c t e r i z e d in that the hydroxycar^¬ boxylic acid product is used as chemical, biochemical and/or polymer component.

16. An apparatus for manufacturing a hy- droxycarboxylic acid product (7) from lignocellulose- based raw material, c h a r a c t e r i z e d in that the apparatus includes

- an effluent feeding means (20) for feeding a first ef^¬ fluent used as a raw material (2) to the apparatus; - a first concentration device (10) for concentrating the first effluent to provide a concentrate (3) ;

- a hydrolysis and fermentation unit (11, 12, 21) for treating the concentrate (3) by hydrolysis to form sac^¬ charides (4) and for fermenting the saccharides (4) to form hydroxycarboxylic acid; and

- a pH controlling means (18a-c) for controlling the pH of the fermentation (12) by using a second effluent (16) .

17. The apparatus according to claim 16, c h a r a c t e r i z e d in that the hydrolysis and fer^¬ mentation unit (21) comprises a hydrolysis device (11) and a fermentation device (12) .

18. The apparatus according to claim 16 or 17, c h a r a c t e r i z e d in that pH controlling means (18a-c) are arranged to control the pH during the fer^¬ mentation of the saccharides.

19. The apparatus according to any one of claims 16 to 18, c h a r a c t e r i z e d in that pH controlling means (18a-c) are arranged to control the pH of the first effluent (2) before the hydrolysis (11) and/or fermentation (12).

20. The apparatus according to any one of claims 16 to 19, c h a r a c t e r i z e d in that the apparatus includes a dewaterer (10) for removing water (17) from the first effluent (2) to provide a concen^¬ trate (3) .

21. The apparatus according to any one of claims 16 to 20, c h a r a c t e r i z e d in that the apparatus includes a first filtering device (10) for filtrating the first effluent (2) to provide a concen^¬ trate (3) .

22. The apparatus according to any one of claims 16 to 21, c h a r a c t e r i z e d in that the hydrolysis device (11) is based on hydrolysis selected from the group of acid hydrolysis, alkaline hydroly- sis, enzymatic hydrolysis and their combinations.

23. The apparatus according to any one of claims 16 to 22, c h a r a c t e r i z e d in that the apparatus includes a second concentration device (15) for concentrating a suspension (5a) containing the hy- droxycarboxylic acid to form the hydroxycarboxylic ac^¬ id product ( 7 ) .

24. The apparatus according to any one of claims 16 to 23, c h a r a c t e r i z e d in that the ap^¬ paratus includes a second filtering device (14) for fil- trating the suspension (5a) containing the hydroxycarboxylic acid after the fermentation (12) to separate lignin and fermentation residue (6) from the hydroxycarboxylic acid suspension (5a) .

25. The apparatus according to claim 23, c h a r a c t e r i z e d in that the second concentration device (15) is a suspension melt crystallization device.

26. The apparatus according to any one of claims 16 to 25, c h a r a c t e r i z e d in that the se^¬ cond effluent used in the pH controlling is a bleaching filtrate.

27. Use of a bleaching filtrate in control^¬ ling the pH of hydrolysis and/or fermentation of a pulp mill effluent in hydroxycarboxylic acid product manufacturing .