WO2024112241A1

WO2024112241A1 - Method for handling filtrates in a process for producing bleached cellulose pulp from recycled textile material

Info

Publication number: WO2024112241A1
Application number: PCT/SE2023/051035
Authority: WO
Inventors: Ann-Sofi NÄSHOLM; Sofia BYLUND; Maria VENNERSTRÖM; Melly KJELLSSON
Original assignee: Valmet Ab
Priority date: 2022-11-24
Filing date: 2023-10-18
Publication date: 2024-05-30
Also published as: SE2230380A1

Abstract

Method for handling one or more filtrates in a process for producing bleached pulp from recycled textile material comprising cellulose, or in a process for bleaching pulp formed from recycled textile material comprising cellulose, the process for producing or bleaching comprising washing (2, 4) and/or dewatering pulp to obtain washed and/or dewatered pulp and one or more filtrates The method comprises subjecting at least a portion of at least one of the filtrates to an ozone treatment step (5) to obtain at least one treated filtrate. The method further comprises recirculating at least a portion of the at least one treated filtrate to the process, and/or providing at least a portion of the at least one treated filtrate as an output for treatment in a wastewater treatment plant (6).

Description

METHOD FOR HANDLING FILTRATES IN A PROCESS FOR PRODUCING BLEACHED CELLULOSE PULP FROM RECYCLED TEXTILE MATERIAL

TECHNICAL FIELD

The invention relates to a method for handling filtrates in a process for producing bleached cellulose pulp from recycle textile material or in a process for bleaching pulp formed from recycled textile material. The invention also relates to processes for producing bleached cellulose pulp from recycle textile material and for bleaching pulp formed from recycled textile material comprising handling filtrates according to the method. The invention also relates to a system for producing bleached cellulose pulp from recycle textile material.

BACKGROUND

Over the recent years, recycling of textile material has gained interest. Processes for recycling cellulose from textile material comprising cellulose are known in the art, see for instance WO2018/073177A1. Recycled cellulose can be used for different purposes, for example for producing viscose. In the above-mentioned publication, the need for de-colorization/bleaching of the recycled textile material is identified, and it is suggested to use a combination of oxygen and ozone bleaching.

Pulping and de-colorization/bleaching of the resulting pulp normally comprises washing and/or dewatering stages resulting in one or more filtrates. The raw material (recycled textile material) is not standardized in the sense that the quality of the recycled textile material and the dyes used for production thereof varies greatly. This means that the content of the filtrates from the washing and dewatering stages varies greatly. When using certain types of recycled textile material, the filtrates may contain large amounts of dyes and/or toxic substances. This is particularly the case for filtrates originating from early in the process, such as from washing before or after a first bleaching stage. Presently available wastewater treatment plants may be unable to handle such filtrates.

SUMMARY

An object of the invention is to provide a method which solves or at least improves on the problems identified in the above background section.

These and other objects are achieved by the present invention by means of a method and a system according to the independent claims. According to a first aspect of the invention, there is provided a method for handling one or more filtrates in a process for producing bleached pulp from recycled textile material comprising cellulose, or in a process for bleaching pulp formed from recycled textile material comprising cellulose, the process for producing or bleaching comprising washing and/or dewatering pulp to obtain washed and/or dewatered pulp and one or more filtrates. The method comprises subjecting at least a portion of at least one of the filtrates to ozone treatment to obtain at least one treated filtrate. The method further comprises recirculating at least a portion of the at least one treated filtrate to the process, and/or providing at least a portion of the at least one treated filtrate as an output for treatment in a wastewater treatment plant.

In other words, at least a portion of at least one of the filtrates from a washing and/or dewatering stage is ozone treated, i.e. the filtrate is treated by introducing ozone thereto. The ozone treatment may result in oxidation of dyes and/or toxic substances and/or reduction of COD/BOD. The filtrate(s) is/are wholly or partly recirculated for instance as washing or dilution liquid to the process for producing bleached pulp or for bleaching pulp. Alternatively, or additionally, the filtrate(s) may be partly or wholly output for treatment in a wastewater treatment plant, i.e. the ozone treatment acts as a pre-cleaning stage prior to wastewater treatment. Ozone treatment of effluents/wastewater per se is known in the art (see for example WO 2017/076474 A1) and will not be described in detail here.

The invention is based on the insight that ozone can be used for advantageous effect not only for bleaching, but also for handling filtrates in processes for producing bleached pulp or for bleaching pulp from recycled textile material. The invention is further based on the insight that, due to the ozone treatment, the filtrate(s) may be sufficiently clean in order to be wholly or partly recirculated for instance as washing or dilution liquid to the process for producing bleached pulp or for bleaching pulp. In other words, the ozone treated filtrate(s) may be recirculated without further treatment. Due to the ozone treatment of the filtrate(s), the load on the wastewater treatment plant can be reduced twofold, firstly by providing a cleaner filtrate thereto, and secondly by reducing the amount of filtrate supplied thereto (by recirculating (part of) the filtrate to the process). Recirculating (part of) the filtrate to the process also reduces freshwater consumption.

In embodiments, the recirculating comprises recirculating at least a portion of the at least one treated filtrate to the process upstream of (flow-wise prior to) the washing and/or dewatering (from where the filtrate is obtained). It is however foreseeable within the scope of the invention that the recirculating comprises recirculating at least a portion of the at least one treated filtrate to the process downstream of (flow-wise after) the washing and/or dewatering from where the filtrate is obtained.

In embodiments, the ozone treatment step comprises adding ozone to the at least one filtrate at a charge 0.1-10 kg/m³.

In embodiments, the ozone treatment step is carried out at a temperature of 30-80 degrees C. Depending on where the at least one filtrate is obtained, the at least one filtrate may require cooling to fall within this temperature range, i.e. the method may further comprise, prior to the ozone treatment step, cooling the at least one filtrate.

In embodiments, the method further comprises, prior to the recirculating and/or providing, filtrating the at least one treated filtrate. The providing may comprise adjusting the pH of the at least one treated filtrate.

In embodiments, the method comprises recirculating at least a portion of the at least one treated filtrate to the process, and/or subjecting at least a portion of the at least one treated filtrate to a wastewater treatment stage (or feeding at least a portion of the at least one treated filtrate to a wastewater treatment plant). The wastewater treatment stage may comprise one or more of the following: sedimentation stage, filtration stage, aeration stage, digestion stage, flotation stage, and/or anaerobic or aerobic bio treatment stage(s).

According to a second aspect of the invention, there is provided a process for bleaching pulp formed from recycled textile material comprising cellulose, comprising subjecting the pulp to at least one bleaching stage, wherein one or more of the at least one bleaching stage is followed or preceded by a washing stage or a dewatering stage, and handling at least one filtrate from the at least one washing stage or dewatering stage using the method according to the first aspect of the invention or embodiments thereof. One or more of the at least one bleaching stage may comprise ozone bleaching. This is advantageous since using ozone for both bleaching and treatment of filtrates can use a common source of ozone.

According to a third aspect of the invention, there is provided a process for producing bleached pulp from recycled textile material comprising cellulose. The process comprises pulping the recycled textile material to form cellulose pulp and bleaching the cellulose pulp using a process according to the second aspect of the invention or embodiments thereof. In embodiments, the process further comprises, prior to the bleaching, washing the cellulose pulp, wherein the handling at least one filtrate from one or more of the at least one washing stage or dewatering stage comprises recirculating at least a portion of the at least one treated filtrate to the washing of the cellulose pulp.

In embodiments, the process further comprises, prior to the bleaching, washing and/or dewatering the cellulose pulp to obtain washed and/or dewatered cellulose pulp and at least one filtrate, further comprising handling the at least one filtrate from the washing and/or dewatering of the cellulose pulp using the method according the first aspect of the invention or embodiments thereof. The filtrate from the washing and/or dewatering prior to the bleaching usually comprises high amounts of dyes and/or toxic substances and is thus advantageously (but not necessarily) output to the wastewater treatment after ozone treatment rather than being recirculated to the process.

In embodiments, the process further comprises at least one dilution stage, wherein said handling at least one filtrate from the washing and/or dewatering stage and/or said handling the at least one filtrate from the washing and/or dewatering of the cellulose pulp comprises recirculating at least a portion of the at least one treated filtrate as dilution liquid to the at least one dilution step. The process may comprise dilution stage(s) forming pretreatment stage(s) in which acidifying chemicals and/or additives are added along with dilution liquid.

According to a fourth aspect of the invention, there is provided a system for producing bleached cellulose pulp from recycled textile material comprising cellulose. The system comprises:

- a pulping arrangement arranged to receive the recycled textile material to produce pulp therefrom, for example by swelling the material under reducing conditions as described in WO2018/073177A1 ;

- at least one bleaching arrangement arranged to bleach pulp obtained from the pulping arrangement, where one or more of the at least one bleaching arrangement is/are ozone bleaching arrangement(s);

- at least one washing and/or dewatering arrangement arranged to wash or dewater pulp received (directly or indirectly) from the pulping arrangement or (directly or indirectly) from a bleaching arrangement of the at least one bleaching arrangement;

- at least one ozone treatment arrangement configured to subject a filtrate from one or more of the at least one washing arrangement to ozone treatment for oxidation of dyes and/or toxic substances and/or reduction of COD/BOD; - optionally, at least one dilution arrangement arranged to dilute pulp from the pulping arrangement or from a bleaching arrangement of the at least one bleaching arrangement, and

- recirculating means configured to: recirculate at least a portion of at least one treated filtrate from the one or more washing or dewatering arrangement to a washing arrangement of the at least one washing or dewatering arrangement and/or to a dilution stage of the at least one dilution stage, and/or to provide at least a portion of the at least one treated filtrate as an output for treatment in a wastewater treatment plant.

At least one, or each, of the washing and/or dewatering arrangement(s) may be twin-roll presses. At least one, or each, of the dilution arrangement(s) may be a standpipe or a dilution screw. The dilution arrangement(s) may form pretreating arrangement(s) by comprising means/nozzle(s) for adding acidifying chemical(s) and/or additive(s).

In embodiments, the system further comprises a cooling arrangement arranged to cool the at least one treated filtrate or said at least a portion at least one treated filtrate. Cooling arrangements are known in the art and will not be described in further detail here.

In embodiments, the system further comprises said wastewater treatment plant. The wastewater treatment plant may be of a type conventionally used for pulping and bleaching processes and may comprise sedimentation, filtration, aeration, digestion, flotation, and/or anaerobic or aerobic bio treatment.

The features of the embodiments described above are combinable in any practically realizable way to form embodiments having combinations of these features. Further, all features and advantages of embodiments described above with reference to the first aspect of the invention may be applied in corresponding embodiments of the second, third and fourth aspects of the invention and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Above discussed and other aspects of the present invention will now be described in more detail using the appended drawings, which show presently preferred embodiments of the invention, wherein: fig.1 schematically illustrates an embodiment of the process according to the third aspect of the invention; fig.2 schematically illustrates another embodiment of the process according to the third aspect of the invention, and fig.3 schematically illustrates yet another embodiment of the process according to the third aspect of the invention.

Fig. 1-3 also illustrate embodiments of the process according to the second aspect of the invention and embodiments of the method according to the first aspect of the invention.

DETAILED DESCRIPTION

Fig. 1 schematically illustrates an embodiment of the process according to the third aspect of the invention. The process comprises pulping 1 the recycled textile material to form cellulose pulp, for instance by swelling the material under reducing conditions as described in WO2018/073177A1. The cellulose pulp is thereafter washed 2, followed by a bleaching stage 3 which may comprise ozone bleaching. After bleaching, the pulp is washed again in a second washing stage to obtain bleached pulp and a filtrate. The filtrate (spent washing liquid) from the washing stage 4 is handled by subjecting the filtrate to an ozone treatment stage 5 in which the filtrate is treated by means of ozone for oxidation of dyes and/or toxic substances and/or reduction of COD/BOD. The ozone treatment may be carried out for example as described in WO 2017/076474 A1. The treated filtrate from ozone treatment stage 5 is output to a wastewater treatment stage 6 (which may or may not be part of the process). The wastewater treatment stage 6 comprises one or more of the following: a sedimentation stage, a filtration stage, an aeration stage, a digestion stage, a flotation stage, and/or anaerobic or aerobic bio treatment stage(s).

Optionally, part (or all of) the treated filtrate is fed/recirculated to the process, more specifically as washing liquid to the first washing stage 2 (dotted arrow line in fig. 1). As can be seen in fig. 1 , the ozone treated filtrate is (optionally) recirculated by being fed directly from the ozone treatment stage 5 to the first washing stage 2, i.e. without further treatment of the filtrate. Alternatively, the filtrate from the first washing stage 2 is handled in the same manner as the filtrate from the second washing stage 4, i.e. by being subjected to the ozone treatment stage 5, where the filtrates from both washing stages are output to the wastewater treatment stage after ozone treating.

It is noted that the ozone treatment stage 5 and the associated recirculation and outputting to the wastewater treatment stage also illustrate an embodiment of the method according to the first aspect of the invention. Stages 2-5 of fig. 1 also illustrate an embodiment of the process according to the second aspect of the invention. Fig. 1 could also be said to illustrate an embodiment of the system according to the fourth aspect of the invention, which embodiment comprises a pulping arrangement 1 , a bleaching apparatus 3, washing apparatuses 2, 4, an ozone treatment arrangement 5 and an optional wastewater treatment plant 6. Such arrangements, apparatuses and plants are all well-known in the art and will not be described in further detail here. Pumps, conduits etc. for feeding the pulp and filtrate(s) between the arrangements, apparatuses and plants are also well-known in the art.

Fig. 2 schematically illustrates another embodiment of the process according to the third aspect of the invention. The process comprises a pulping stage 11 , washing stages 12, 14, an ozone treatment stage 15 and an optional wastewater treatment 16 corresponding to stages 1 , 2, 4, 5 and 6 in fig. 1 described above.

The embodiment in fig. 2 differs from the embodiment in fig. 1 in that the bleaching comprises two bleaching stages 13c, 13e with an intermediate washing stage 13d. Optionally, a pretreating stage 13a followed by a dewatering stage precedes the first bleaching stage 13c.

The pulp from the pulping stage 11 is optionally pretreated 13a by adding sulphuric acid to reduce the pH of the pulp to within a range from 2 to 3. The pretreating optionally also comprises adding one or more additives, the additives comprising at least one of oxalic acid, EDTA and magnesium sulfate. Thus, the pretreating stage may be referred to as an aq-stage. The additive(s) may be added together with, or simultaneously with the at least one acid. The pretreatment comprises diluting the pulp to low consistency prior to adding acid. Depending on the desired consistency, the acidified pulp is subjected to an optional dewatering/thickening stage 13b such that the pulp is provided to the first bleaching stage 13c at high consistency (at least 30%, preferably within a range from 35-42%). The first bleaching stage 13c comprises ozone bleaching, i.e. bleaching by means of adding ozone. Optionally, the ozone bleaching may be followed directly by chlorine dioxide bleaching, i.e. the first bleaching stage may be a (ZD)-stage. After the first bleaching stage 13c, the pulp is washed 13d to remove dissolved material from the first bleaching stage.

The second bleaching stage 13e may comprise ozone bleaching and/or hydrogen peroxide bleaching and/or chlorine dioxide bleaching.

The filtrate from washing stage 14 is handled by subjecting the filtrate to an ozone treatment stage 15 in which the filtrates are treated by means of ozone for oxidation of dyes and/or toxic substances and/or reduction of COD/TOC/BOD. Optionally, the filtrate(s) from the dewatering stage 13b and/or the washing stage 13d is also handled using the ozone treatment stage 15 (dotted lines).

At least part (or all) of the treated filtrate from ozone treatment stage 15 is recirculated as washing liquid to the washing stage 12, and the rest is output to the wastewater treatment stage 16. Alternatively, or additionally, to the recirculation to washing stage 12, at least part of the treated filtrate from ozone treatment stage 15 is recirculated as dilution liquid to the pretreating stage 13a (dotted line). In embodiments where solely the filtrate from the washing stage 14 is handled by the ozone treatment stage 15, at least part of the treated filtrate from ozone treatment stage 15 may be recirculated as washing liquid to the washing stage 13d (dotted line). As can be seen in fig. 2, the ozone treated filtrate(s) is/are recirculated by being fed directly from the ozone treatment stage 15 to stage(s) 12/13a/13d, i.e. without further treatment of the filtrate(s).

Optionally, the process comprises handling filtrate from the washing stage 12 by subjecting the filtrate to an additional ozone treatment stage (not shown, corresponding to stage 15), where the treated filtrate is output to the wastewater treatment stage 16.

In alternative embodiments, all of the treated filtrate(s) from the ozone treatment stage(s) is output to the wastewater treatment. In such embodiments, the filtrates from at least one, or all, of the washing stages 12, 13d, 14 and dewatering stage 13b is handled in this manner, optionally with a single ozone treatment stage.

It is noted that the ozone treatment stage 15 and the associated recirculation and outputting to the wastewater treatment stage also illustrate an embodiment of the method according to the first aspect of the invention. Stages 12-15 of fig. 2 also illustrate an embodiment of the process according to the second aspect of the invention.

Fig. 2 could also be said to illustrate an embodiment of the system according to the fourth aspect of the invention, which embodiment comprises a pulping arrangement 11 , bleaching apparatuses 13c, 13c, washing apparatuses 12, 13d, 14, an ozone treatment arrangement 15, an optional pretreatment/dilution arrangement 14, an optional dewatering arrangement 13b and an optional wastewater treatment plant 16. Such arrangements, apparatuses and plants are all well-known in the art and will not be described in further detail here. Pumps, conduits etc. for feeding the pulp and filtrate(s) between the arrangements, apparatuses and plants are also well-known in the art. Fig. 3 schematically illustrates yet another embodiment of the process according to the third aspect of the invention. The process comprises a pulping stage 21 , washing stage 22, optional pretreatment/dilution stage 23a, optional dewatering stage 23b, a first bleaching stage 23c, washing stage 24, an ozone treatment stage 25 and an optional wastewater treatment stage 26 corresponding to stages 11 , 12, 13a, 13b, 13c, 14, 15 and 16 in fig. 2 described above.

The embodiment in fig. 3 differs from the embodiment in fig. 2 in that the second bleaching stage 23g (corresponding to stage 13e in fig. 2) is preceded by an optional pretreatment/dilution stage 23e followed by an optional dewatering stage 23f.

In the pretreatment/dilution stage 23e, the washed and bleached pulp from washing stage 23d is pretreated by adding sulphuric acid to reduce the pH of the pulp to within a range from 2 to 3. The pretreating optionally also comprises adding one or more additives, the additives comprising at least one of oxalic acid, EDTA and magnesium sulfate. Thus, the pretreating stage may be referred to as an aq-stage. The additive(s) may be added together with, or simultaneously with the at least one acid. The pretreatment comprises diluting the pulp to low consistency prior to adding acid. Depending on the desired consistency, the acidified pulp is subjected to an optional dewatering/thickening stage 23f such that the pulp is provided to the second bleaching stage 23g at high consistency (at least 30%, preferably within a range from 35-42%). The second bleaching stage 23g comprises ozone bleaching, i.e. bleaching by means of adding ozone. Optionally, the ozone bleaching may be followed directly by chlorine dioxide bleaching or hydrogen peroxide bleaching, i.e. the second bleaching stage may be a (ZD)- or (ZP)-stage. After the second bleaching stage 23g, the pulp is washed 24 to remove dissolved material.

The filtrates from washing stage 24 are handled by subjecting the filtrate to the ozone treatment stage 25 in which the filtrates are treated by means of ozone for oxidation of dyes and/or toxic substances and/or reduction of COD/TOC/BOD. Optionally, the filtrate from dewatering stage 23f and/or from the washing stage 23d and/or from the dewatering stage 23b is/are also handled using the ozone treatment stage 25.

At least part (or all) of the treated filtrate from ozone treatment stage 25 is recirculated as washing liquid to the washing stage 22, and the rest is output to the wastewater treatment stage 26. Alternatively, or additionally, to the recirculation to washing stage 22, at least part of the treated filtrate from ozone treatment stage 25 is recirculated as dilution liquid to the pretreating stage 23a and/or to the pretreating stage 23e and/or to the washing stage 23d. As can be seen in fig. 3, the ozone treated filtrate(s) is/are recirculated by being fed directly from the ozone treatment stage 25 to stage(s) 22/23a/23d/23e, i.e. without further treatment of the filtrate(s).

Optionally, the process comprises handling filtrate from the washing stage 22 by subjecting the filtrate to an additional ozone treatment stage (not shown, corresponding to stage 25), where the treated filtrate is output to the wastewater treatment stage 26.

In alternative embodiments, all of the treated filtrate(s) from the ozone treatment stage(s) is output to the wastewater treatment. In such embodiments, the filtrates from at least one, or all, of the washing stages 22, 23d, 24 and dewatering stages 23b, 23f are handled in this manner, optionally with a single ozone treatment stage.

It is noted that the ozone treatment stage 25 and the above-described recirculating and outputting to the wastewater treatment stage also illustrate an embodiment of the method according to the first aspect of the invention. Stages 22-25 of fig. 3 also illustrate an embodiment of the process according to the second aspect of the invention.

Fig. 3 could also be said to illustrate an embodiment of the system according to the fourth aspect of the invention, which embodiment comprises a pulping arrangement 21 , bleaching apparatuses 23c, 23g, washing apparatuses 22, 23d, 24, an ozone treatment arrangement 25, and optional pretreating/diluting arrangements 23a, 23e, optional dewatering arrangements 23b, 23f and wastewater treatment plant 26. Such arrangements, apparatuses and plants are all well-known in the art and will not be described in further detail here. Pumps, conduits etc. for feeding the pulp and filtrate(s) between the arrangements, apparatuses and plants are also well-known in the art.

The description above and the appended drawings are to be considered as non-limiting examples of the invention. The person skilled in the art realizes that several changes and modifications may be made within the scope of the invention. In particular, the above-described recirculation of the ozone treated filtrates are only examples. It is foreseen within the scope of the invention that any filtrate from any washing or dewatering stage in the process can be handled by ozone treatment and thereafter being partly or wholly recirculated to any stage of the process for example as washing liquid and/or dilution liquid and/or being partly or wholly output to one or more wastewater treatment stage(s)/plant(s).

Claims

1 . A method for handling one or more filtrates in a process for producing bleached pulp from recycled textile material comprising cellulose, or in a process for bleaching pulp formed from recycled textile material comprising cellulose, said process for producing or bleaching comprising washing (2, 4; 12, 14; 22, 23d, 24) and/or dewatering (13b; 23b, 23f) pulp to obtain washed and/or dewatered pulp and one or more filtrates, the method comprising: subjecting at least a portion of at least one of the filtrates to an ozone treatment step (5; 15; 25) to obtain at least one treated filtrate, and recirculating a portion of the at least one treated filtrate to the process, and providing a portion of the at least one treated filtrate as an output for treatment in a wastewater treatment plant (6; 16; 26).

2. Method according to claim 1 , wherein said recirculating comprises recirculating a portion of the at least one treated filtrate to the process upstream of the washing and/or dewatering.

3. Method according to any of the preceding claims, wherein said ozone treatment step comprises adding ozone to the at least one filtrate at a charge 0.1-10 kg/m3.

4. Method according to any of the preceding claims, wherein said ozone treatment step is carried out at a temperature of 30-80 degrees C.

5. Method according to any of the preceding claims, further comprising, prior to said ozone treatment step, cooling the at least one filtrate.

6. Method according to any of the preceding claims, further comprising, prior to said recirculating and/or providing, filtrating the at least one treated filtrate.

7. Method according to any of the preceding claims, wherein said providing comprises adjusting the pH of the at least one treated filtrate.

8. A process for bleaching pulp formed from recycled textile material comprising cellulose, comprising: subjecting the pulp to at least one bleaching stage (3; 13c, 13e; 23c, 23g), wherein one or more of the at least one bleaching stage is followed or preceded by a washing stage (2, 4; 12, 14; 22, 23d, 24) or a dewatering stage (13b; 23b, 23f); handling at least one filtrate from the at least one washing stage or dewatering stage using the method according to any of the preceding claims.

9. Process according to claim 8, wherein one or more of said at least one bleaching stage (3; 13c, 13e; 23c, 23g) comprises ozone bleaching.

10. A process for producing bleached pulp from recycled textile material comprising cellulose, comprising: pulping (1 ; 11 ; 21) the recycled textile material to form cellulose pulp, and bleaching the cellulose pulp using a process according to any of claims 8-9.

11. Process according to claim 10, further comprising, prior to said bleaching, washing the cellulose pulp, wherein said handling at least one filtrate from one or more of the at least one washing stage or dewatering stage comprises recirculating a portion of the at least one treated filtrate to the washing of the cellulose pulp.

12. Process according to any of claims 10-11 , further comprising, prior to said bleaching, washing and/or dewatering the cellulose pulp to obtain washed and/or dewatered cellulose pulp and at least one filtrate, further comprising handling the at least one filtrate from the washing and/or dewatering of the cellulose pulp using the method according to any of claims 1-7.

13. Process according to any of claims 10-12, further comprising at least one dilution step, wherein said handling at least one filtrate from the washing and/or dewatering stage and/or said handling the at least one filtrate from the washing and/or dewatering of the cellulose pulp comprises recirculating a portion of the at least one treated filtrate as dilution liquid to the at least one dilution step.

14. A system for producing bleached cellulose pulp from recycled textile material comprising cellulose, said system comprising: a pulping arrangement arranged to receive the recycled textile material to produce pulp therefrom; at least one bleaching arrangement arranged to bleach pulp obtained from the pulping arrangement; at least one washing and/or dewatering arrangement arranged to wash or dewater pulp from the pulping arrangement or from a bleaching arrangement of the at least one bleaching arrangement; at least one ozone treatment arrangement configured to subject a filtrate from one or more of the at least one washing or dewatering arrangement to ozone treatment; optionally, at least one dilution stage arranged to dilute pulp from the pulping arrangement or from a bleaching arrangement of the at least one bleaching arrangement, and recirculating means configured to: recirculate a portion of at least one treated filtrate from the one or more washing or dewatering arrangement to a washing arrangement of the at least one washing or dewatering arrangement and/or to a dilution stage of the at least one dilution stage, and to provide a portion of the at least one treated filtrate as an output for treatment in a wastewater treatment plant.

15. System according to claim 14, further comprising a cooling arrangement arranged to cool the at least one treated filtrate or said at least a portion at least one treated filtrate.