WO1998036124A1

WO1998036124A1 - Process for treating a cellulose-containing substance

Info

Publication number: WO1998036124A1
Application number: PCT/US1998/002667
Authority: WO
Inventors: Richard Robert Rubin
Original assignee: L'harmonie S.A.; Handelman, Joseph, H.
Priority date: 1997-02-14
Filing date: 1998-02-13
Publication date: 1998-08-20
Also published as: AU6158398A

Abstract

A process for treating a cellulose-containing substance (20) includes bringing the cellulose-containing material (20), in particulate form, into contact with an aqueous liquid (19), and thereafter subjecting the cellulose-containing substance (20) to an electric arc. The cellulose-containing substance is thus treated and at least two different products are produced.

Description

PROCESS FOR TREATING A CELLULOSE-CONTAINING SUBSTANCE

THIS INVENTION relates to a process for treating a cellulose-containing and/or hemicelluloεe-containing substance.

According to the invention, there is provided a process for treating a cellulose-containing substance, which process includes bringing the cellulose-containing substance, in particulate form, into contact with an aqueous liquid; and thereafter subjecting the cellulose-containing substance to an electric arc, thereby treating the cellulose-containing substance and producing at least two different products.

As used in this specification, the term "cellulose-containing substance" refers to a substance containing cellulose and/or hemicellulose, the term "cellulose" also refers to hemicellulose, and the term "σellulosic" also refers to materials containing hemicellulose .

The bringing into contact of the cellulose- containing substance with the aqueous liquid may comprise introducing the cellulose-containing substance onto the surface of the aqueous liquid, and allowing at least a major- portion of the cellulose-containing substance to float- on the surface of the aqueous liquid. Instead, the bringing of the cellulose-containing substance into contact with the aqueous liquid may comprise admixing the cellulose-containing substance and the aqueous liquid to provide an admixture in the form of a paste.

The cellulose-containing substance may have a particle size of less than about 0,8mm, preferably less" than about 0,5mm, and most preferably the cellulose- containing substance has a particle size of less than about 0,4mm. The cellulose-containing substance may be comminuted prior to bringing it into contact with the aqueous liquid. A mill such as a pin mill may be used to comminute the cellulose-containing substance, or the cellulose-containing substance may be comminuted using comminuting apparatus having a high speed cutting member.

If required, the cellulose-containing substance may be dried before it is comminuted. Typically, the cellulose- containing substance is dried to a moisture content of at most about 15% by mass, e.g. about 10%, or less.

As described hereinbefore, the admixture of the cellulose-containing substance and the aqueous liquid may be in the form of a paste. Instead, in a more preferred embodiment, the admixture may be in the form of a liquid with the cellulose-containing substance particles floating on the aqueous liquid. The process may thus include feeding the cellulose-containing substance particles onto the surface of the aqueous liquid at a rate such that caking or lumping of the particles is inhibited or avoided. The maximum feed rate is affected by, inter alia, the potential dif erence of the electrical current used to form the' electrical arc, the . pH of the aqueous liquid, the cellulose-containing substance used, and the additives present in the aqueous liquid.

The aqueous liquid may be pre- reated prior to the bringing into contact of the cellulose-containing substance with the aqueous liquid, thereby to accelerate the. process and/or increase the yield of the products.

The pre-treatment of the aqueous liquid may include the addition of an acid to the aqueous liquid, thereby to lower 'the pH of the aqueous liquid to a maximum of about 4. For some cellulose-containing substances, e.g. oat bran, the pH of the aqueous liquid iε preferably reduced to a maximum of about 2. It is believed that a lower pH generally increases the spread of the electric arc, increases the rate of production of the products, and in some cases increases the degree of hydrolization or breaking up of the cellulose-containing substance.

The acid may be an organic acid, selected from the group consisting of citric acid, carbonic acid, ascorbic ^• acid, methanoic acid, ethanoic acid, propanoic acid, tartaric acid, and mixtures thereof. Instead, the acid may be an inorganic acid, such as HCl, HjSO* or HN0₃.

Instead, or additionally, the pre-treatment of the aqueous liquid may include introducing a mineral sa t- containing component into the aqueous liquid. The mineral sal -containing component may comprise NaCl, C1, g^'S0₄, sodium sulphite, sodium sulphate, sodium diεulphite, bittern, or mixtures thereof. The mineral salt-containing component may be introduced into the aqueous liquid to provide a concentration of the mineral salt-containing component in the aqueous liquid of about 0,5g/100ml.

Instead, or additionally, the pre-treatment of the aqueous liquid may include adding to the -aqueous liquid a suitable additive. The additive may be selected from the group consisting of iodine tincture, hydrogen peroxide, sea water, and mixtures thereof. The additive may, instead, be a product commercially available in the USA under the trade name _CON_CENTRACE TRACE MINERAL DROPS from Trace Minerals Research, P O Box 429, Roy, Utah, 84067. When used, the CONCENTRACE TRACE MINERAL DROPS may be added to the aqueous liquid in a concentration of about 0,3% v/v. When used, the sea water may be added to the aqueous liquid in a. concentration of about 2% v/v. It is believed that the introduction or addition of a mineral sal -containing component or an additive as described above increases the spread of the electric arc over the surf ce of the aqueous liquid, and increases the rate and/or yield of the process.

The electric arc may be induced between at least one pair of spaced electrodes, with at least one electrode of the pair of electrodes not being in contact with the cellulose-containing substance or the aqueous liquid. In one embodiment of the invention, one of the electrodes may comprise a receptacle of an electrically conductive material, in which the liquid- admixture is contained while it is subjected to the electric arc.

In another embodiment, one of the electrodes may be submerged in the liquid admixture.

In yet a further embodiment, one of the electrodes may be an electrically conductive, support surface on which the admixture in the form of a paste is thinly spread.

Preferably, neither of the electrodes is in contact with the cellulose-containing substance or the aqueous liquid, to inhibit corrosion of the electrodes.

When .more than one pair of electrodes is employed, the electrodes may be connected in series. In order to do so, one electrode of a first pair is connected to one electrode of a second pair, and so on, with the last electrode of the last pair connected to earth, and the other electrode of the first pair connected to the output of a voltage generator. Each pair of electrodes may be suspended above an associated separate container containing the aqueous liquid and cellulose-containing substance.

There may be a potential difference of at least 2000V between the electrodes when an alternating current is employed. Preferably, the potential difference between the electrodes is at least 6000V when an alternating current is employed. An alternating current of about 15 kHz has been -successfully used, but it is believed that a source of 50Hz alternating current provides better results if connected in parallel with a capacitor having a capacitance of, say 0,01 μfarad.

As mentioned hereinbefore, the electrodes may be suspended above the aqueous liquid in close proximity to the aqueous liquid so that the electric arc passes over the surface of the aqueous liquid between the electrodes . When the' electrodes are thus suspended above the aqueous liquid they are typically spaced 0,3 - 1,0 cm from the surface of the liquid admixture. It is believed that the optimum distance between the electrodes and the aqueous liquid is the maximum distance which still allows an arc to form. Boiling of the aqueous liquid below the or each suspended electrode is to be avoided. The electrodes are typically spaced at least 5cm apart when ^' a potential difference of 6000V is used, to inhibit electric arc formation directly between the electrodes, instead of .along the surface of the aqueous liquid. However, it is to be appreciated that the minimum distance between the electrodes is a function of the potential difference and additives used.

The process may be conducted as a batch, εemi- batch or continuous process.

The cellulose-containing substance may be selected from the group consisting of wood, leaves, grass, a cereal bran, and mixtures thereof. Typically, the aqueous liquid is water. It is also believed that wood, e.g. in the form of saw dust, can be used in the process of the invention. However, when wood is used, the pH of the' aqueous liquid should be about 3 at the most, and a mineral salt and/or an oxidant such as hydrogen peroxide should be added to the aqueous liquid.

The products may comprise a sludge product and a liquid product containing at least one dissolved constituent. When the admixture is in the form of a paste, it may be admixed with a further quantity of aqueous liquid, to produce the sludge product and the liquid product . The process may include separating the sludge product from the liquid product e.g. by filtration. The process may also include treating the liquid product to recover at least some of the dissolved constituents therefrom. This may be achieved by, e.g., boiling off the aqueous liquid under vacuum. Instead, the liquid product may be passed through a separation column to provide liquid fractions having different concentrations of dissolved constituents. The sludge product may be recovered by, e.g., washing it on a sieve or mesh and drying it. Instead, or in addition the sludge product and the liquid product may be treated further, e.g. by a fermentation or enzymatic process or a further separation process.

The invention extends to a sludge product and a liquid product when produced by the process.

The sludge product may include, as a constituent thereof agglomerated hydrolization products of cellulose, water insoluble protein, and/or water insoluble celluloεic fibre.

The dissolved constituent of the liquid product may comprise a water soluble carbohydrate, a water soluble hydrolization product of cellulose, a water soluble protein, or mixtures thereof. It is believed that when wood is used, lignin is one of the dissolved constituents of the liquid product.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which

Figure 1 shows one embodiment of apparatus for carrying out a process for treating a cellulose-containing substance in accordance with the invention, on a batch basis;

Figure 2 shows another embodiment of apparatus for carrying out the process for treating a cellulose- containing substance in accordance with the invention, on a batch basis; Figure 3 shows an embodiment of apparatus for carrying out the process for treating a cellulose- containing substance in accordance with the. invention, on a continuous basis; and

Figure 4 shows an embodiment of apparatus for carrying out the process for treating a cellulose- containing substance in accordance with the invention, on a semi-batch basis.

Referring to Figure 1, reference . numeral 10 generally indicates apparatus for carrying out a process for treating a cellulose-containing substance in accordance with the invention.

The apparatus 10 includes a hollow stainless steel container 12. The container 12 is earthed via a conductor 1 . Accordingly, the container 12 acts as an electrode.

A second electrode 16 is suspended above the container 12. The electrode 16 is adjustable so that a free end 18 of the electrode 16 can be located at a selected distance above the surface of contents of the container 12. The electrode IS is connected to a voltage generator (not shown) .

In use, the container 12 is partly filled with water 19. A quantity of wheat bran is comminuted to a particle size of about 0,4mm. The wheat bran particles are fed or introduced into the container 12 on the surface of the water 19. However, since they have a lower density than the water, the wheat bran particles float on the surface of the water 19 to provide a layer 20 of wheat bran particles on the surface of the water 19. The volume of wheat bran is selected such that caking or lumping of the wheat bran is avoided or minimized. If desired, the pH of the water may be lowered to about 4, by addition of an acid such as HC1, H₂S0₄, HN0₃, citric acid, carbonic acid, methanoic acid, ethanoic acid, prσpanoiσ acid, tartaric acid or ascorbic acid. However, pretreatment with an acid will lead to an acidic liquid product being produced by the process, which liquid product may require further treatment before it can be used or disposed of in an environmentally acceptable manner.

The elevation of the electrode 16 is adjusted so that its free end 18 is about 0,3 to 1,0 cm from a surface 22 of the bran particle layer 20. A potential difference of about 6000 volt is generated by the voltage generator between the container 12 (which acts as an electrode) and the electrode 16, to produce an electric arc spanning the gap between the free end 18 of the electrode 16 and the surface 22 of the bran particle layer 20. The voltage generator includes a step-up transformer having an output of 6000V, with a 0,01 μfarad capacitor connected in parallel to the output of the transformer.

The bran particles in the bran particle layer 20 are drawn towards the free end 18 of the electrode 16 and are subjected to the heat produced by the electric arc. Without being burnt or scorched to an appreciable extent, the bran particles in the bran particle layer 20 are thereby treated, with at ^"least two different products being produced. A first product, which may include agglomerated hydrolization products of cellulose, settles at the bottom of the container 12 to form a ^"sludge 24. A liquid; product containing at least one dissolved constituent is also formed.

The liquid product is decanted from the container 12, and the dissolved constituents can be separated therefrom by any method known to those skilled in the art, e.g. by boiling off the water under vacuum. The sludge 24 can be dried at least partially to provide a product which may include hydrolization products of cellulose, protein, and/or σellulosic fibre. Instead of decanting the liquid product from the container 12, the contents of the container 12 may be admixed, to break up the agglomerated hydrolization products, thereby to dissolve them in the water in so far as they are water soluble. The remainder of the sludge 24 and the liquid product are then separated, e.g. by filtration. The liquid product .may thus include dissolved hydrolization products of cellulose, and the sludge product may include cellulosic fibres.

Referring to Figure 2, another apparatus in accordance with the invention for carrying out the process for treating a cellulose-containing substance, is generally indicated by reference numeral 30 and unless otherwise indicated the same reference numerals used above are used to designate the same or similar parts or features .

Unlike the ^" apparatus 10, the apparatus 30 does not have a hollow container 12, but instead has . a planar steel' late 32, which is earthed via the conductor 14. The apparatus 30 is used similarly to the apparatus 10. However, unlike the apparatus 10 where the wheat bran particles are in the form of a layer 20 on top of the water 19, the wheat bran particles are in the form of a paste 34 spread in a layer on the plate 32. Thus, the volumetric ratio of wheat bran particles to water is about 1:1. An arc is thus produced between the electrode end 18 and the plate 32 , and passes through or over the surface of the paste 34, to treat the wheat bran in the -paste. Typically, the electrode end 18 is moved around so that the electric arc treats the whole paste. The treatment products are not automatically separated from each other when the paste 34 is subjected to the electric arc, as is the case when the process is carried out with the apparatus 10. After having been subjected to the electric arc, the paste 34 may be admixed with water to provide the sludge product and the liquid product.

Using the apparatus 10 for carrying out the process of the invention, instead of the apparatus 30, thus has the advantage that the separation of the products occurs' automatically and simultaneously while the wheat bran layer 20 is subjected to the electric arc, and it is also believed that less scorching or burning may occur when the apparatus 10 is used compared to when the apparatus 30 is used. The apparatus 10 also does not require that the- electrode end 18 be moved around.

Referring to Figure 3, another apparatus for carrying out the process for treating a cellulose- containing substance on a continuous basis, is generally indicated by reference numeral 50.

The apparatus 50 includes a glass channel 52 open at an end 54 and closed at an opposite end 56. Two electrodes 58 are suspended above the glass channel. 52 by supports 60 so that an end 62 of each electrode 58 is , inside the glass channel 52. The electrodes 58 are longitudinally spaced 4cm apart in the channel, and are located closer to the end 54 than the end 56. An adjustment nut 64 is proviςLed for each electrode 58 to adjust the elevation of the end 62 of each electrode 58 inside the glass channel 52. The electrodes 58 are connected to a voltage generator as hereinbefore described (not shown) by means of electrical conductors 65\

A separation device, generally indicated by reference numeral 70 is provided at a lower elevation than the glass channel 52, below the end 54 of the glass channel 52. The separation device 70 includes an open-topped container 72, the.opening in the container 72 being defined by an upper edge 73 of the container wall 76. A mesh 74 is suspended inside the container 72 from the upper edge 73 of the container wall 76 by means of suspension hooks 78. A discharge ramp 66 leads from the open end 54 of the glass channel 52 to the mesh 74.

A liquid outlet 80 leads from the container 72 to a suction side of a pump 82. A liquid recycle line 84 leads from a discharge side of the pump 82 into a funnel 100. A pump recycle line 86 leads from the liquid recycle line 84 back to the container 72. A product withdrawal line 88 leads from the liquid recycle line 84. A valve 90 is located in the product withdrawal line 88 for controlling discharge of product through the line 88. A valve 92 is located in the liquid recycle line 84 downstream from the product withdrawal line 88.

The funnel 100 is suspended above the glass channel 52 in the vicinity of its closed end 56, with a funnel outlet 102 located inside the glass channel 52. A fresh water feed line 104 also leads into the funnel 100. A valve 106 is located in the fresh water feed line 104.

A hopper 110 is also suspended above the glass channel 52 between the funnel 100 and the electrodes 58. The hopper 110 has a narrow, recticulated discharge end 112 for discharging solid particles into the glass channel 52.

In use, fresh water is fed through the fresh water feed line 104, by means of the valve 106, into the funnel 100, from where it enters the glass channel 52 through the funnel outlet 102. The water runs towards the open end 54 where it leaves the glass channel 52 along the discharge ramp 66 to fall through the mesh 74 into the container 72. The pump 82 is started and the water is returned to the funnel 100 through the liquid outlet 80 and the liquid recycle line 84, with the valve 92 in an open position. The valve 90 in the product withdrawal line 88 is initially in a closed position. When a sufficient quantity of water is circulating through the apparatus 50, the valve 106 is closed. A quantity of comminuted wheat bran with a particle size of about 0,4mm is placed inside the hopper 110. The elevation of the electrodes 58 is adjusted with the adjustment nuts 64 so that the free ends 62 of the electrodes 58 are suspended about 0,3 to 1,0 cm from the surface of the water flowing along the channel 52. A potential difference of about 6000 volt is generated between the two electrodes 58 by the voltage generator, to produce an electric arc, which is conducted along the surface of the water flowing along the channel 52, between the ends 62 of the electrodes 58.

Bran particles are discharged from the hopper 110 into the glass channel 52 through the recticulated opening 112. If desired, the hopper 110 may be vibrated to induce a steady flow of bran particles or any other means of inducing a steady flow of bran particles may be used, e.g by using a rotary vane feeder or a fluidised bran particle feed. Bran particles drop onto the surface of the water flowing along the glass channel 52 and are carried underneath the electrodes 58 toward the open end 54. When the bran particles are between the electrodes 58, they are subjected to the heat produced by the electric arc. Without being burnt or scorched to an appreciable extent, the ' bran particles in the bran particle layer 20 are thereby treated, as described above, to produce a liquid product having dissolved constituents and a sludge product. The . liquid product, carrying the sludge product, is transferred from the glass channel 52 along discharge ramp 66 onto the mesh 74. The sludge product is retained on the mesh 74 whilst the liquid product passes through the mesh 74.

The sludge product on the mesh 74 is continuously or periodically removed from the mesh 74 by any method known to those skilled in the art. The liquid product in the container 72 is withdrawn through the liquid outlet 80 and pumped, by means of the pump 82 and the liquid recycle line 84, back into the funnel 100 to be returned to the glass - channel 52. With the continuous adding of bran particles into the glass channel 52, the concentration of the. dissolved constituents in the liquid product gradually increases. When the dissolved constituents have reached a desired ^'concentration, a portion of the liquid product containing the dissolved constituents can be continuously withdrawn through the product withdrawal line 88. The withdrawal of the liquid product through- the product withdrawal discharge line 88 is controlled by the valve 90.

Fresh make up water is fed to the funnel 100 through the fresh water feed line -104 and the valve 106 at a rate to make up for the loss . of water in the liquid product passing through the product withdrawal line 88. The valve 92 is used to control the- level of liquid in the glass channel 52, and the pump recycle line 86 recycles excess output from the pump 82 back to the container 72 in response to the valve 9 . It is to be appreciated that the pump recycle line 86 iε sized small enough to allow the liquid product to be pumped to the funnel 100 through the liquid recycle line 84.

It will be thus appreciated that the apparatus 50 provides means for carrying out the process of the invention on a continuous or semi-continuous basis. The liquid product containing the dissolved constituents passing through the product withdrawal line 88 can be further treated, for example, to separate the dissolved constituents from the water as described above. The sludge removed from the mesh 74 can also be treated further as described above.

Referring to Figure 4, another apparatus in accordance with the invention for carrying out the process for treating a cellulose-containing substance, is generally indicated by reference number 200 and unless otherwise indicated, the same reference numerals used in Figure 1 are used to designate the same or similar parts or features .

A second container 202 iε suspended inside the first container 12. The second container 202 has two raised vertical outlets 204. The electrodes 16 are suspended above the outlets 204 so that their free ends 18 are about 0,3 - 1cm from the outlets 204. The electrodes 16 are connected to a voltage generator as hereinbefore described. A hopper 206 is suspended centrally above the container 202.

_A liquid circulation line 208 has an inlet 210 into the container 202 and an outlet 212 from the container 12 ; A pump (not shown) is provided in the liquid circulation line 208.

In use, the containers 12, 202 and the water circulation line 208 are filled with water and the pump is started to circulate water through the apparatus 200, as indicated by arrows 214. Bran particles are discharged from the hopper 206 onto the surface of the water entering the container 202 from the inlet 210. The operation of the hopper 206 may- be similar "to the operation of the hopper 110 as described above. The bran particles ^"float on the surface of the water and are carried towards the vertical outlets 204. A potential difference of about 60D0V is generated by the voltage generator between the electrodes 16, to produce an electric arc stretching across the surface of the water in the container 202, between the free ends 18 of the electrodes 16. The bran particles are thus subjected to the electric arc, producing at least two different products. A sludge product, which may include agglomerated hydrolization products of cellulose, descends through the outlets 204 and settles at the bottom of the container 12 to form a sludge 24. A liquid product comprising the water and at least one dissolved constituent is also formed, and is circulated through the apparatus 200 as indicated by the arrows 214.

The sludg -24 can be removed periodically .from the container 12. If desired, f esh feed water and the liquid product can be added and withdrawn respectively, in a similar manner as with the apparatus 50 described above.

The Applicant, has thus found that by means of the process of the invention, as illustrated, a non-water soluble cellulose- and/or hemicellulose-containing substance can surprisingly easily be converted into at least two products, one of which is a liquid product having dissolved constituents derived from the cellulose and/or hemicellulose substance.

Claims

CLAIMS ;

1 . A process for treating a cellulose- containing substance , which process includes bringing the cellulose- containing substance , in particulate form, into contact with an aqueous liquid; and thereafter subj ecting the cellulose-containing substance to an electric arc , thereby treating the cellulose- containing substance and producing at least two dif ferent products .

2 . A -process as claimed in Claim 1 , in which the bringing into contact of the cellulose- containing substance with the aqueous liquid comprises introducing the cellulose- containing substance onto the surface of the aqueous liquid, and allowing at least a major portion of the cellulose-containing substance to float on the surface of the aqueous liquid.

3 . A process as claimed in Claim 1 , in which the bringing of the cellulose- containing substance into contact with the aqueous liquid comprises admixing the cellulose -containing substance and the aqueous liquid to form a paste .

. A process a╬╡ claimed in any one of the preceding claims , in which the cellulose- containing substance has a particle size of less than 0 , 8mm.

5. A process as claimed in Claim 4, in which the cellulose-containing substance has a particle size of less than 0,4mm.

6. A process as claimed in any one of the preceding claims, in which the cellulose-containing substance i╬╡ comminuted prior to bringing it into contact with the aqueous liquid.

7. A process as claimed in Claim 6, in which the cellulose-containing substance i╬╡ dried before it is comminuted.

8. A process as claimed in Claim 7, in which the cellulose-containing substance is dried to a moisture content of at most 15% by mass.

9. A process as claimed in any one of the preceding claims, in which the aqueous liquid i╬╡ pre-treated prior to the bringing into contact of the cellulose-containing substance with the aqueous liquid, thereby to increase the yield of the products .

10. A process a╬╡ claimed in Claim 9, in which the pre- treatment of the aqueous liquid includes the addition of an acid to the aqueous liquid, - thereby to lower the pH of the aqueous liquid to a maximum of 4.

11. A process as claimed in Claim 10, in which the pH of the aqueous liquid is reduced to a maximum of 2.

12. A process a╬╡ claimed in Claim 10 or Claim 11, in which the acid u╬╡ed is an organic acid.

13. A process as claimed in Claim 12, in which the organic acid is selected from the group consisting of citric acid, carbonic acid, ascorbic acid, methanoic acid, ethanoic acid, propanoic acid, tartaric acid, and mixtures thereof.

14. A process as claimed in Claim 10 or Claim 11, in which the acid u╬╡ed is an inorganic acid.

15. A process as claimed in Claim 9, in which the pre- treatment of the aqueous liquid includes introducing a mineral salt-containing component into the aqueous liquid.

16. A process a╬╡ claimed in"Claim 15, in which the mineral salt-containing component comprises NaCl, KCl, MgS0, sodium sulphite, sodium sulphate, sodium disulphite, bittern, or mixtures thereof .

17. A process a╬╡ claimed in any one of Claims 9 to 16 inclusive, in which the pre-treatment of the aqueous liquid includes adding to the aqueous liquid an additive selected from the group consisting of iodine tincture, hydrogen peroxide, sea water, and mixtures thereof.

18 . A process a╬╡ claimed in any one of the preceding claims , in which the electric arc is induced between a pair of spaced electrodes , at least one of which is not in contact with the cellulose- containing substance or the aqueous liquid.

19 . A process a╬╡ claimed in Claim 18 , in which neither of the electrodes is in contact with the cellulose-containing substance or the aqueous liquid.

20 . A process as claimed in Claim 18 or Claim 19 , in which there is a potential difference of at least 2000V between the electrodes when an alternating current is employed.

21 . A process as claimed in Claim 20 , in which the potential difference between the electrodes i╬╡ at least 6000V when an alternating current is employed .

22 . A- proce╬╡╬╡ a╬╡ claimed in Claim 20 or Claim 21 , in which a voltage generator is used to generate the potential difference between the electrodes , a capacitor being connected in parallel with an output of the voltage generator .

23 . A pro╧âe╬╡╬╡ a╬╡ claimed in any one of the preceding claims , in which the cellulose-containing ' substance is selected from the group consisting of wood, leaves , grass , a cereal bran, and mixtures thereof .

24. A process as claimed in any one of the preceding claims, in which the products comprise a sludge product and a liquid product containing at least one dissolved constituent, the process including separating the sludge product from the liquid product.

25. A process a╬╡ claimed in Claim 24, which includes treating the liquid product to recover at least some of the dissolved constituents therefrom.

26. A sludge product when produced by the process as claimed in Claim 24.

27. A sludge product as claimed in Claim 26,ΓÇ₧ which includes, as a constituent thereof, agglomerated hydrolization products of cellulose, water insoluble protein, and/or water insoluble cellulosic fibre.

28. A liquid product when produced by the process a╬╡ claimed in Clai -24 or Claim 25.

29. A liquid product as claimed in Claim 28 in which the dissolved constituent comprises a water soluble carbohydrate, a water soluble hydrolization product- of cellulose, a water soluble protein, or mixtures thereof.

30. A process for treating a cellulose-containing substance as claimed in Claim 1, substantially as herein described and illustrated.

31. A sludge product a╬╡ claimed in Claim 26, substantially as herein described and illustrated.

32. A liquid product a╬╡ claimed in Claim 28, substantially as herein described and illustrated.

33. A new process or product, substantially as herein described.