JPH1017701A - Degradation of cellulose derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce COD pollution caused from waste water by efficiently, subjecting a cellulose derivative such as cellulose ether to biodegradation. SOLUTION: A cellulose derivative such as cellulose ether (CIVIC or HEC, etc.) is degraded by treating with active oxygen (especially ozone treatment) and subjecting to an activated sludge treatment. An efficiency of the treatment is increased and a treating cost can be reduced by performing the treatment with the active oxygen under an alkaline condition, in the presence of a peracid (especially hydrogen peroxide), or in the presence of the peracid and under the alkaline condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a decomposition method useful for efficiently biodegrading a cellulose derivative such as cellulose ether.

[0002]

2. Description of the Related Art In addition to natural polymers such as starch and alginic acid, synthetic polymers such as polyvinyl alcohol and polyethylene glycol, natural water-insoluble natural materials such as cellulose are chemically used as water-soluble polymer materials. There are semi-synthetic polymers that have been modified to introduce various functional groups to impart water solubility. Such water-soluble polymers are used in a wide range of industrial fields depending on their properties. On the other hand, semi-synthetic polymers and synthetic polymers have high functionality and excellent usability,
It is stable even in the natural environment and has poor degradability. Further, among semi-synthetic polymers, cellulose derivatives produced and used industrially in large quantities are roughly classified into two types, cellulose esters and cellulose ethers, depending on the mode of bonding of functional groups. Underneath, the functional group is easily hydrolyzed, and after being turned into cellulose, it is easily decomposed completely. On the other hand, cellulose ether has very strong decomposability under a natural environment due to its strong bond. For example, carboxymethylcellulose (hereinafter, may be simply referred to as CMC), which is a typical compound of cellulose ether, is a constituent unit of cellulose, 3
It is produced by reacting glucose having two hydroxyl groups with monochloroacetic acid, and becomes water-soluble when the number of monochloroacetic acids bound per glucose (degree of substitution, DS) is 0.4 or more. As CMC, DS
About 0.6 to 2 CMCs are industrially produced and used. When such CMC is dissolved in water, it becomes a stable and harmless viscous solution. Therefore, CMC is used in wide fields such as food, cosmetics, industrial paste, civil engineering, and mining.
Further, as the cellulose ether, in addition to CMC, hydroxyethylcellulose (hereinafter sometimes simply referred to as HEC), hydroxypropylcellulose, methylcellulose, ethylcellulose, diethylaminoethylcellulose, or a cellulose derivative having a plurality of functional groups introduced (for example, Hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, etc.) have similar properties and are used in a wide range of fields like CMC.

However, the fact that these cellulose ether derivatives are stable means that they are less decomposable in a natural environment even if they are disposed of after industrial use. In fact, cellulose ethers are less susceptible to enzymatic degradation by microorganisms in their natural environment (MGWirick, J. Polymer
Sci., 6, 1965 (1968)). Therefore, the cellulose ether in the wastewater cannot be completely decomposed even by activated sludge, which is a general wastewater treatment method, and causes COD-type contamination (Yasuda, Proceedings of the Sanitary Engineering Symposium 16,65 (198
0)). On the other hand, research on the degradation of cellulose by microorganisms has been conducted for a long time, and aerobic bacteria, anaerobic bacteria, actinomycetes, filamentous fungi, and hyperthermia bacteria have been reported as the degradation microorganisms (Murao et al., "Cellulase" Kodansha) , 198
7 years). In addition, the mechanism of decomposition of cellulose by the enzymes of those microorganisms is such that endo-β-1,4-glucanase randomly cleaves the cellulose chain, and exo-β-1,
4-glucanase acts on the non-reducing end of the cellulose chain to produce cellobiose. It is then decomposed to glucose by β-1,4-glucosidase (Murao et al.,
"Cellulase" Kodansha, 1987).

Many studies on the biodegradation of CMC have been conducted on cellulose ether derivatives, and the isolation of degrading bacteria, the purification of degrading enzymes (CMCases) and their properties have been reported (Yoshida et al. 3), 105 (1991), J. Kamama
oto et al. J. Ferment. Technol., 57 (3), 163 (197
9), T. Hatano et al. J. Ferment. Bioeng., 71 (5), 3
13 (1991), and MGWirick, J. Water Poll. Contro
l Fed., 46 (3), 512 (1974)). However, there is no report that CMC was completely degraded like cellulose. As described above, cellulose ether derivatives are essentially difficult to biodegrade in nature. Therefore, when a cellulose derivative such as a cellulose ether derivative is industrially used and discharged as waste, it cannot be decomposed to carbon dioxide even when subjected to an activated sludge method that is a general treatment of industrial wastewater.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for efficiently decomposing a cellulose derivative. It is another object of the present invention to provide a method for biodegradation of a cellulose derivative such as cellulose ether, which is almost completely biodegradable by a simple operation. Still another object of the present invention is to provide a biodegradation method capable of efficiently treating a waste liquid containing a cellulose derivative and effectively preventing environmental pollution.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that when a cellulose derivative is pretreated and subjected to an activated sludge method, the cellulose derivative can be completely decomposed. The present invention has been completed. That is, in the method of the present invention, the cellulose derivative is decomposed by treating the cellulose derivative with active oxygen and treating with activated sludge. In this method, the active oxygen treatment is often an ozone treatment, and the active oxygen treatment comprises (1)
The reaction may be performed in the presence of at least one of an alkali and (2) a peracid. The peracid includes hydrogen peroxide and the like, and the cellulose derivative includes cellulose ethers and the like.

In the method of the present invention, a method combining the above conditions, for example, ozone treatment of a cellulose derivative in the presence of (1) alkali, (2) hydrogen peroxide, or (3) alkali and hydrogen peroxide. Thereafter, a method of biodegrading the cellulose derivative by performing an activated sludge treatment is also included. Further, the above method may be applied to a solid cellulose derivative, or may be applied to a drainage containing the cellulose derivative to biodegrade the cellulose derivative. In the present specification, "activated sludge treatment" is not limited to the case of treating wastewater or sewage containing organic matter, but by immersion in activated sludge.
It is used to include the case where microorganisms act on solid components (fibers, films, sheets, etc.) to decompose them.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention comprises a pretreatment step of treating a cellulose derivative with active oxygen, and a step of treating the pretreated cellulose derivative with activated sludge. If pretreatment and activated sludge treatment are combined, cellulose derivative can be biodegraded with extremely high efficiency by activated sludge treatment, probably because the pretreatment causes the cellulose derivative to be preliminarily partially degraded and changed to a form easily biodegradable. . [Cellulose Derivative] The present invention is applicable to the decomposition of various cellulose derivatives, and the type thereof is not particularly limited. Examples of the cellulose derivative include cellulose ester derivatives (organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, and cellulose phthalate; cellulose nitrate, cellulose sulfate,
Inorganic acid esters such as cellulose phosphate; mixed acid esters such as cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose nitrate acetate; and polycaprolactone-grafted cellulose acetate and the like; cellulose ether derivatives (eg, methyl cellulose, Alkyl cellulose such as ethyl cellulose, aralkyl cellulose such as benzyl cellulose and trityl cellulose,
CMC, carboxyalkylcellulose such as carboxyethylcellulose, HEC, hydroxyethylmethylcellulose, cationized HEC, carboxymethylHE
C, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylhydroxypropylcellulose and other hydroxyalkylcellulose or derivatives thereof, cyanoethylcellulose, aminoethylcellulose, diethylaminoethylcellulose and the like). These cellulose derivatives can be effectively biodegraded singly or as a mixture of two or more.

The average degree of polymerization of the cellulose derivative is, for example, about 10 to 1,000, preferably about 50 to 900, and more preferably about 200 to 800. The average degree of substitution of the cellulose derivative depends on the type of the substituent and the like. For example, it can be appropriately selected from a range of about 0.5 to 3 (for example, 1 to 3). In the method of the present invention, not only cellulose esters but also cellulose ethers which are considered to be poor in biodegradability can be effectively biodegraded. for that reason,
The present invention is effective for biodegradation of a cellulose ether derivative. The cellulose derivative as the object to be treated may be a solid (powder and granular, fibrous, a planar shape such as a film or sheet, a molded product having a three-dimensional structure such as a three-dimensional molded product),
It may be an aqueous or non-aqueous solution or dispersion containing a cellulose derivative. Preferred treatment objects include a treatment liquid [aqueous or non-aqueous drainage (particularly wastewater)] containing a cellulose derivative (particularly a water-soluble cellulose derivative such as a cellulose ether derivative). The solvent of the aqueous liquid to be treated is not limited to water alone, but may be water and a hydrophilic or water-soluble solvent (for example, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, and ethers such as dioxane and tetrahydrofuran). And the like). The solvent of the non-aqueous liquid to be treated includes various organic solvents, for example, hydrocarbons, alcohols, esters, ketones, ethers and the like.

The concentration of the cellulose derivative in the liquid to be treated is
There is no particular limitation as long as the processing efficiency is not impaired.
0 ppm to 30% by weight, preferably 100 ppm to 20%
% By weight, more preferably from about 500 ppm to 10% by weight. [Active Oxygen Treatment] In the present invention, the active oxygen treatment as the pretreatment is performed by using a component containing active oxygen having high reactivity or a component generating active oxygen (hereinafter, these may be simply referred to as an active oxygen component). It can be performed using: The type of the active oxygen component is not particularly limited, and the active oxygen can be generated by discharge, ultraviolet irradiation, or the like. A preferred active oxygen treatment is an ozone treatment. Ozone is
For example, it can be generated using a conventional device such as an ozone generator, the ozone concentration is not particularly limited, and low concentration ozone by air ozonation, concentrated ozone, or purely separated oxygen is ozonized. Any of high concentration ozone and the like may be used.

When the reaction time (contact time) with an active oxygen component (particularly ozone) is increased, the total organic carbon (hereinafter simply referred to as T
(Abbreviated as OC) is remarkable, and the final treatment rate by the activated sludge treatment is good. However, from an economic viewpoint, the activated oxygen treatment (particularly, ozone treatment) is shortened and the load of the activated sludge treatment is increased. Is advantageous. For example, the treatment of the active oxygen component (particularly, the ozone treatment) results in 1 to 50% (preferably 5 to 5%) of the TOC of the cellulose derivative such as CMC.
0%, more preferably about 10 to 50%), the subsequent activated sludge treatment causes 45 to 1 to 1 of the entire TOC.
00% (preferably 50 to 100%, more preferably 60 to 100%) can be removed. The treatment amount of the active oxygen component (particularly, ozone) can be selected according to the treatment temperature, the form of the treatment object (solid or liquid, etc.), the concentration of the treatment liquid, the treatment method, and the like. )
Is about 1 to 500 mol, preferably about 10 to 450 mol, and more preferably about 25 to 400 mol.

The active oxygen treatment may be performed by flowing or aerating a predetermined amount of the active oxygen component with respect to the object to be processed. For example, the reaction may be performed in a reaction vessel). The temperature of the active oxygen treatment is not particularly limited,
For example, it can be selected from the range of 0 to 50 ° C., preferably about 15 to 40 ° C., and the time of the active oxygen treatment depends on the form and concentration of the object to be treated, the concentration of the active oxygen component, and the like.
It can be selected from the range of 1 minute to 6 hours, preferably 5 minutes to 5 hours, more preferably about 10 minutes to 3 hours. When the active oxygen treatment and the activated sludge treatment are combined, the degree of decomposition (TOC reduction) of the cellulose derivative by the activated sludge treatment (TOC) is small even if the degree of decomposition (decrease in TOC) is small.
) Can be significantly reduced. And C
Without being affected by the degree of substitution of the cellulose derivative such as MC, the distribution of the substituents, the degree of polymerization, etc., even a cellulose derivative having a very low degree of substitution with a very low degree of biodegradability can be degraded with high efficiency.

[0013] The pretreatment may be carried out by causing an active oxygen component to act directly on the cellulose derivative.
When the liquid to be treated is pretreated, the pretreatment conditions can be selected in a wide range from acidic to alkaline, for example, in a range of about pH 2 to 13. To further increase the pretreatment efficiency,
The cellulose derivative is advantageously pretreated under neutral to alkaline conditions (for example, about pH 6 to 14, preferably about pH 7 to 13, and more preferably about pH 9 to 12). In particular, in the presence of alkali, (1) alkaline conditions (for example, pH 8 to 14, preferably pH 9 to 1)
3, more preferably about 10 to 13). For example, ozone treatment (ozone oxidation)
Is usually around neutral, but in the case of CMC, it is preferable to carry out ozone treatment under alkaline conditions with alkali in order to prevent the pH of the liquid to be treated after ozone treatment from becoming 7 or less. In this ozone treatment, CM
When a liquid to be treated having a C concentration of 1000 ppm is treated with ozone, it is advantageous that the initial pH of the liquid to be treated is strongly alkaline (for example, an alkaline pH of 12 or more). In order to suppress a decrease in pH, a pH adjuster such as a buffer may be added.

Further, it is effective to combine the pretreatment with a means for improving the reaction efficiency of the active oxygen component (particularly, ozone) (for example, ultraviolet irradiation or addition of peracid). In particular, (2) the ozone treatment in the coexistence of peracid has a high treatment efficiency because OH radicals are effectively generated. Peroxy acids include hydrogen peroxide, acyl derivatives of hydrogen peroxide [eg,
Organic peroxides such as formic acid, peracetic acid, perbenzoic acid, perphthalic acid, benzoyl peroxide, and lauroyl peroxide], peroxo acids or salts thereof (for example, peroxo acids such as perchloric acid and permanganic acid or these) (Eg, sodium perchlorate, sodium permanganate) and the like, and hydrogen peroxide [eg, Na ₂ SiO ₃ .H ₂ O ₂ .H ₂ O, N
aBO ₂ · H ₂ O ₂ · 3H ₂ O]. These peracids can be used alone or in combination of two or more. The type of peracid can be selected according to the type of the cellulose derivative, the pretreatment system solvent, the pretreatment method, and the like.

[0015] Preferred peracids include hydrogen peroxide which has little adverse effect on the subsequent activated sludge. Especially,
Hydrogen peroxide is suitable for use in wastewater (wastewater) containing a cellulose derivative in a water treatment plant because the decomposition product is safe water and does not require post-treatment, and is also advantageous in cost. The amount of (2) peracid can be selected within a range that can improve the pretreatment efficiency, and is, for example, 0.1 to 100 mol, preferably 1 to 75 mol per 100 parts by weight of the cellulose derivative (solid content). And more preferably 5 to 5
It is about 0 mol (for example, 10 to 50 mol). By such pretreatment, the cellulose derivative can be preliminarily and effectively decomposed, and for example, the TOC of the liquid to be treated containing the cellulose derivative can be reduced. In particular, the pretreatment,
When the reaction is carried out in the presence of (1) an alkali (particularly under alkaline conditions) or (2) a peracid (particularly hydrogen peroxide), the cellulose derivative can be effectively preliminarily decomposed.

In order to further improve the pretreatment efficiency,
It is effective to combine the above conditions and (3) treat the cellulose derivative with an active oxygen component (particularly ozone) in the presence of an alkali (particularly alkaline) and in the presence of a peracid (particularly hydrogen peroxide). . In the pretreatment in the presence of such a peracid (particularly, hydrogen peroxide), when a pH adjuster such as a buffer is added to suppress the acidity of the liquid to be treated in the pretreatment step, active oxygen ( TOC by ozone treatment
Can be significantly increased, and the TOC of 10 to 70 can be significantly reduced within a very short time as compared with a system in which no peracid (hydrogen peroxide) is added.
% (Particularly 20 to 70%) can be removed. for that reason,
The load of subsequent activated sludge treatment can be greatly reduced while efficiently pretreating the cellulose derivative in the pretreatment step. [Activated Sludge Treatment] The activated sludge treatment can be performed by a conventional method [eg, preparation of activated sludge by aeration, mixing with wastewater or wastewater and formation of flocs (sedimentation separation), return of sludge, etc.]. As activated sludge, various microorganisms having biodegradability for cellulose derivatives (for example,
An aerobic bacterium, an anaerobic bacterium, an actinomycete, a filamentous bacterium, a hyperthermic bacterium, etc.) can be used, and activated sludge containing a microorganism conditioned by the treatment of a cellulose derivative may be used. This microorganism may be isolated and subjected to biodegradation of the cellulose derivative.
Further, instead of or together with the microorganism, a decomposing enzyme (for example, cellulase) produced by the microorganism or a processed product of the microorganism (such as a crushed product) may be used.

Activated sludge treatment is carried out under conditions that do not impair the activity of microorganisms and enzymes, for example, a temperature of 10 to 40 ° C. and a pH of 4 to 10.
Can be done in degrees. INDUSTRIAL APPLICABILITY The method of the present invention is useful for biodegrading various cellulose derivatives by microorganisms, and is particularly useful for treating wastewater or sewage containing a water-soluble cellulose derivative.

[0018]

According to the method of the present invention, since the active oxygen treatment and the activated sludge treatment are combined, the cellulose derivative can be decomposed efficiently. In particular, even a small biodegradable cellulose derivative such as a cellulose ether derivative can be almost completely biodegraded by a simple operation. Therefore, waste liquid containing a cellulose derivative can be efficiently treated, and environmental pollution can be effectively prevented.

[0019]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 In order to investigate the influence of the pH of the liquid to be treated, 0.1% by weight of C
80 ml of the MC aqueous solution was placed in a glass reaction vessel (capacity: 100 m
1), and ozone-treated by passing air containing ozone through. The ozone treatment was performed by introducing ozone-containing air for 120 minutes at an air flow rate of 1 L / min and an ozone generation amount of 7.12 mg / min by the ozone generator. In addition,
The pH of the CMC aqueous solution (liquid to be treated) was adjusted to 4 to 12 using hydrochloric acid and sodium hydroxide.

After ozone treatment, 30 ml of each treated water was put into a Sakaguchi flask (capacity: 100 ml), the pH was adjusted to 7, and 0.3% of yeast extract 1% solution was used as a micronutrient.
At the same time, 0.3 ml of the activated sludge suspension was inoculated. Activated sludge suspension, return sludge of sewage treatment,
Media (DIFCO, Nutrient Broth)
For 2 days with shaking, centrifuged at 12,000 rpm for 10 minutes, and resuspended in 1 ml of 10 mM phosphate buffer. Then, at a temperature of 30 ° C. and 140 rpm
When the change in TOC was measured over time during the culture, the results shown in FIG. 1 were obtained. As shown in FIG. 1, the higher the initial pH of the ozone treatment, the better the biodegradability.

Example 2 In order to examine the effect of the ozone treatment time, ozone treatment and activated sludge treatment were carried out in the same manner as in Example 1 except that the ozone treatment was carried out at a pH of the liquid to be treated of 12 and a treatment time of 30 to 240 minutes. Then, the result shown in FIG. 2 was obtained. As is clear from FIG. 2, as the ozone treatment time becomes longer, the TOC is reduced only by the ozone treatment, and the treatment rate is remarkably improved by the biodegradation treatment, and the treatment efficiency reaches a maximum of 95%. Example 3 The pH of the liquid to be treated containing CMC having different substitution degrees and molecular weights was adjusted to 12, and the ozone treatment and the activated sludge treatment were performed in the same manner as in Example 1. As a result, the results shown in FIG. 3 were obtained. The substitution degree and viscosity of the test CMC are as follows. The viscosity was measured with a rotational viscometer (25 ° C., 60 rpm) using an aqueous solution having the concentration shown in parentheses.

Sample viscosity (cps) Degree of substitution (DS) CMC-1 37 (1% by weight) 0.67 CMC-2 17 (1% by weight) 0.88 CMC-358 (1% by weight) 1.31 CMC −48 (2% by weight) 0.73 CMC-5 267 (1% by weight) 0.68 As shown in FIG. 3, the CMC-3 having a higher degree of substitution is more ozone-treated than the other CMCs. Although the decrease in TOC is slightly large, the TOC after biodegradation is almost the same. Therefore, CMC can be effectively and efficiently processed regardless of the structure of the CMC, such as the degree of substitution and the molecular weight.

Example 4 A buffer [Kortov's potassium phosphate / sodium borate buffer (pH 7.
0 and 9.0)], a liquid to be treated, the pH of which is adjusted using
The solution to be treated (pH adjusted without using a buffer)
Ozone treatment was carried out in the same manner as in Example 1 except that 7.0 and 9.0) were used. When the TOC by the ozone treatment was measured, the result shown in FIG. 4 was obtained. As shown in FIG. 4, the TOC of the liquid to be treated whose pH has been adjusted with the buffer solution is reduced by the ozone treatment. The liquid to be treated adjusted to pH 7.0 with a buffer solution is subjected to ozone treatment (120 minutes),
6.7, and TOC was also reduced by 10%. On the other hand, the pH of the liquid to be treated adjusted to pH 9.0 with the buffer solution was 8.4 even after the ozone treatment, and the TOC was reduced by 30%.

Subsequently, biodegradation was performed by activated sludge treatment in the same manner as in Example 1. As shown in FIG. 4, the total TOC was reduced by 40% in the liquid to be treated adjusted to pH 7.0 with a buffer. The concentration of the liquid to be treated adjusted to pH 9.0 with a buffer solution was 50%. On the other hand, in the liquids to be treated whose pH was adjusted without using a buffer, the TOC was significantly reduced in all cases. Example 5 While adding 100 mg of hydrogen peroxide to the liquid to be treated,
Using the buffer solution of pH 7 of Example 4, ozone treatment was performed in the same manner as in Example 1. FIG. 5 shows changes in TOC over time due to the ozone treatment. As shown in FIG. 5, TOC was reduced by 80% only by ozone treatment for 120 minutes.

To this ozone-treated solution, 0.1 ml of a 1% solution of catalase (manufactured by Sigma) was added to decompose excess hydrogen peroxide, and the same biodegradation test as in Example 1 was performed.
As shown in FIG. 6, ozone treatment 90 minutes and 120 minutes
Min, TOC was almost completely removed, and the ozone treatment showed a removal efficiency of 80% or more even in 60 minutes. Example 6 To examine the effect of the ozone treatment time, 0.1% by weight of HE was used.
Erlenmeyer flask (capacity 300 ml) with 150 ml of C aqueous solution
, And air containing ozone was aerated while stirring with a magnetic stirrer. In the ozone treatment, the HEC aqueous solution was adjusted to pH 12 using sodium hydroxide, the air flow rate was 1.67 L / min, and the amount of ozone generated by the ozone generator was 1
Performed by introducing ozone-containing air at 2.0 mg / min for 60-240 minutes.

After adjusting each treated water to pH 7, 1.5 ml of a 1% yeast extract was added as a trace nutrient. The aeration tank sludge was washed twice with 10 mM phosphate buffer (pH 7), resuspended in the same buffer, 1.5 ml of this suspension was inoculated, and cultured with shaking at 30 ° C. and 97 rpm. FIG. 7 shows the TOC measurement results. As shown in FIG. 7, the biodegradability of HEC was significantly improved by the combination of the ozone treatment and the activated sludge treatment, like the CMC. Example 7 To compare the ozone treatment with the ozone treatment in the presence of hydrogen peroxide, 190 mg of hydrogen peroxide was added to the liquid to be treated adjusted to pH 7 with a buffer solution, and ozone treatment was performed in the same manner as in Example 6. Processed. FIG. 8 shows the change in TOC due to the ozone treatment. As shown in FIG. 8, as with CMC, H
EC also showed greater decomposition than ozone alone due to ozone oxidation in the presence of hydrogen peroxide.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of Example 1.

FIG. 2 is a graph showing the results of Example 2.

FIG. 3 is a graph showing the results of Example 3.

FIG. 4 is a graph showing the results of Example 4.

FIG. 5 is a graph showing the results of ozone treatment in Example 5.

FIG. 6 is a graph showing the results of ozone treatment and activated sludge treatment of Example 5.

FIG. 7 is a graph showing the results of Example 6.

FIG. 8 is a graph showing the results of Example 7.

Claims (7)

[Claims] 1. A method for decomposing a cellulose derivative, wherein the cellulose derivative is treated with active oxygen and then treated with activated sludge. 2. The method for decomposing a cellulose derivative according to claim 1, wherein the active oxygen treatment is an ozone treatment. 3. The method for decomposing a cellulose derivative according to claim 1, wherein the treatment with active oxygen is performed under at least one of (1) an alkaline condition and (2) a condition in which a peracid coexists. 4. The method for decomposing a cellulose derivative according to claim 3, wherein the peracid is hydrogen peroxide. 5. The method according to claim 1, wherein the cellulose derivative is a cellulose ether. 6. A cellulose derivative which is subjected to an activated sludge treatment after ozone treatment of the cellulose derivative in (1) alkaline conditions, (2) in the presence of hydrogen peroxide, or (3) in the presence of alkaline and hydrogen peroxide. Biodegradation method. 7. A biodegradation method for a cellulose derivative, comprising subjecting a waste liquid containing the cellulose derivative to ozone treatment and then treating with activated sludge.