KR101562300B1 - Method for treating 1,4-dioxane-containing wastewater, and treatment device - Google Patents

Abstract

In the biological treatment of 1,4-dioxane-containing wastewater using 1,4-dioxane-decomposing bacteria, the problem of the atmospheric release of 1,4-dioxane is effectively solved by a simple constitution which does not require a special decomposition apparatus . The treatment apparatus (10) comprises a treatment device (10) for treating wastewater containing 1,4-dioxane, which comprises an aerosol (14A) for aerating wastewater and decomposes 1,4- Dioxane-decomposing bacteria and bringing the 1,4-dioxane-decomposing bacteria into contact with the wastewater while air-aerating the wastewater; and a water treatment tank (12) And returning means (14) for returning 1,4-dioxane in the gas to the biological treatment tank (12).

Description

TECHNICAL FIELD The present invention relates to a method for treating 1,4-dioxane-containing wastewater,

The present invention relates to a method and an apparatus for treating 1,4-dioxane-containing wastewater, and particularly relates to 1,4-dioxane-decomposing bacteria, Containing wastewater and a treatment apparatus.

1,4-dioxane is generally used as a solvent or the like, and is often used as a solvent for paints and the like. It is also contained in detergents such as commercially available polyoxyalkyl ethers. Because of this, 1,4-dioxane is produced through factory wastewater from a manufacturing plant producing 1,4-dioxane or a manufacturing plant producing polyoxyalkyl ether, and household wastewater using a detergent containing polyoxyalkyl ether Sewage (sewage) and so on.

However, since 1,4-dioxane is a water-soluble, hardly decomposable substance, it can hardly be decomposed by biological treatment or solid-liquid separation treatment in a sewage treatment plant, have.

On the other hand, 1,4-dioxane was detected in a wide range in the environmental pollution survey of the designated chemical substance performed by the EPA, and contamination particularly in a water environment such as a river or a lake was reported. It has also been reported that 1,4-dioxane is detected from groundwater.

Based on this background, with the revision of the water supply method in April 2004, the content of 1,4-dioxane as a drinking water standard was set at 0.05 mg / L. In April 2010, environmental standard values have been established, and a treatment technique for efficiently decomposing and removing 1,4-dioxane in wastewater is desired.

Conventionally, as a method for decomposing and removing 1,4-dioxane in wastewater, there has been proposed a facilitated oxidation method in which ozone treatment is mainly used in combination with hydrogen peroxide treatment and ultraviolet ray treatment to promote the formation of OH radicals (see, for example, Patent Document 1 ~ 3). It is also known to add a hydrogen peroxide solution under a metal catalyst to form an OH radical.

However, the accelerated oxidation method and the Fenton oxidation method disclosed in Patent Documents 1 to 3 have a problem in that the power consumption and the chemical usage fee are large and the running cost is increased. For this reason, development of a biological treatment method capable of treatment at low cost is required.

Conventionally, the biological treatment of 1,4-dioxane is said to be difficult, and a detailed report on the biological treatment is very small. Among them, the applicant of the present application proposed that the activity of a microorganism capable of decomposing 1,4-dioxane (hereinafter referred to as "1,4-dioxane-degrading bacteria") is improved and applied to wastewater treatment Document 4).

Japanese Patent Application Laid-Open No. 2001-029966 Japanese Patent Application Laid-Open No. 2001-121163 Japanese Patent Application Laid-Open No. 2000-202466 Japanese Unexamined Patent Application Publication No. 2008-306939

However, the Applicant has found that the following problems are encountered after the concrete wastewater (for example, sewage) is specifically treated by using 1,4-dioxane decomposing bacteria.

That is, in the case of biodegradation treatment in a biological treatment apparatus having 1,4-dioxane-decomposing bacteria, aerobic (aerobic) conditions are required, so that when air is aerated, 1,4- There is a problem that a part of the air is discharged to the atmosphere. However, installing a special decomposition device for decomposing 1,4-dioxane emitted from wastewater has a drawback that the apparatus cost is increased.

DISCLOSURE OF THE INVENTION The present invention has been made in view of such circumstances, and it is an object of the present invention to solve the problem of the 1,4-dioxane decomposition bacteria in the biological treatment of 1,4- It is an object of the present invention to provide a method and apparatus for treating 1,4-dioxane-containing wastewater that can be effectively solved by a simple configuration that does not require a decomposition apparatus.

In order to achieve the above object, the invention related to claim 1 is a process for producing 1,4-dioxane-decomposing bacteria which decomposes 1,4-dioxane and a process for treating the wastewater by contact with air in a biological treatment tank And a returning step of returning 1,4-dioxane in the gas discharged from the wastewater to the biological treatment tank by the air-aeration of the biological treatment tank.

According to the present invention, 1,4-dioxane in a gas released by an air-aquarium when biologically treating 1,4-dioxane in a biological treatment tank is returned to the biological treatment tank again for biological treatment. This makes it possible to construct a closed system for 1,4-dioxane treatment centering on a biological treatment tank with a simple structure, so that there is no need for a special decomposition device for decomposing the released gas The problem of air emission can be solved.

According to claim 2 of the present invention, there is provided a method of treating wastewater containing 1,4-dioxane, which comprises: a comprehensive immobilizing support comprising a 1,4-dioxane-decomposing bacterium for decomposing 1,4- And a biological treatment step of bringing the wastewater into contact with the air in the biological treatment tank while air-aeration.

According to the present invention, the 1,4-dioxane decomposition efficiency is improved by using the inclusion immobilization pellets, and the concentration of 1,4-dioxane in the wastewater can be maintained at a low concentration. Therefore, the amount of 1,4-dioxane discharged from the wastewater by air aeration can be greatly reduced.

In addition, in the case of decomposing 1,4-dioxane physically and chemically in a special decomposition apparatus, a decomposition waste liquid is generated, and a device for performing this treatment is also required.

In the treatment method of the present invention, it is preferable to control so that the dissolved oxygen demand (DO) in the wastewater by the air aerator is in the range of 2 to 6 mg / L.

By adjusting the dissolved oxygen demand (DO) in the wastewater to be in the range of 2.0 to 6.0 mg / L, the amount of 1,4-dioxane in the wastewater and the amount of 1,4- The balance of the amount of oxalic acid is improved, and the decomposition efficiency of 1,4-dioxane in the biological treatment tank can be enhanced. A more preferable range of the dissolved oxygen demand (DO) in the wastewater is 3.0 to 5.0 mg / L.

In the treatment method of the present invention, in the recycling step, the gas discharged from the wastewater is scrubbed to absorb 1,4-dioxane in the gas into the scrubbing water (water) It is preferable to return to the biological treatment tank.

In the treatment method of the present invention, it is preferable to use treated water in the biological treatment tank as the scrubbing water. It is also possible to use tap water or industrial water as the scrubbing water. However, when the treated water in the biological treatment tank is used, the water retention time in the biological treatment tank is not increased, The decomposition efficiency of 4-dioxane can be kept high.

In the treatment method of the present invention, it is preferable that the gas discharged from the wastewater is returned as the gas for air-aeration in the biological treatment tank in the returning step. By this, 1,4-dioxane in the gas discharged from the wastewater can be returned to the biological treatment tank in a simple configuration.

In order to attain the above object, the invention related to claim 7 is an apparatus for treating wastewater containing 1,4-dioxane, comprising aeration means for aeration of the wastewater, Dioxane-decomposing bacteria which decompose the wastewater, and which brings the wastewater into contact with the 1,4-dioxane-decomposing bacteria while air-aerating the wastewater; And returning the 1,4-dioxane in the gas to the biological treatment tank.

According to claim 7, the present invention is constituted as an apparatus, and the problem of air release of 1,4-dioxane which was a conventional problem can be solved by a simple constitution. This makes it possible to construct a closed system for treating 1,4-dioxane with a simple structure, centering on a biological treatment tank, so that a special decomposition apparatus for decomposing the released gas is not required, I can solve the problem.

According to claim 8 of the present invention, there is provided an apparatus for treating wastewater containing 1,4-dioxane, comprising aeration means for aeration of the wastewater, And a biological treatment tank having at least a collectively immobilized carrier immobilizing 4-dioxane-degrading bacteria and bringing the wastewater into contact with the collectively immobilized carrier while air-aerating.

The invention according to claim 8 has a comprehensive immobilization carrier in which 1,4-dioxane-decomposing bacteria capable of decomposing 1,4-dioxane are entrapped and immobilized, so that 1,4-dioxane decomposition efficiency is improved, 4-dioxane concentration can be maintained at a low concentration. Therefore, the amount of 1,4-dioxane discharged from the wastewater by air aeration can be greatly reduced.

In the treatment apparatus of the present invention, a control means for controlling the balance between the amount of 1,4-dioxane in the wastewater and the amount of 1,4-dioxane in the gas released from the wastewater, It is preferable to include a DO measurement means for measuring the dissolved oxygen demand in the wastewater and an aeration amount controller for adjusting the amount of air bubbles from the aeration means to a predetermined dissolved oxygen demand based on the measurement result of the DO measurement means . This makes it possible to increase the decomposition efficiency of 1,4-dioxane in the biological treatment tank as described above.

In the treatment apparatus of the present invention, it is preferable that the returning means includes: scrubbing the gas discharged from the wastewater to absorb 1,4-dioxane in the gas into the scrubbing water, and returning the scrubbing water to the biological treatment tank Processing apparatus. Thereby, the gas discharged from the wastewater can be returned to the biological treatment tank in a simple configuration.

In the treatment apparatus of the present invention, the returning means may include a piping connecting the head space formed with the closed structure of the biological treatment tank and the aeration means, and a gas supply means provided in the piping, And a blowing fan for blowing the air. This is another mode of the returning means, and the gas discharged from the wastewater can be returned to the biological treatment tank in a simple configuration.

In the treatment apparatus of the present invention, the biological treatment tank may include a lid member covering the biological treatment tank, a supply port through which the wastewater is supplied to the biological treatment tank, and a water supply port A water sealing structure is preferably provided.

This makes it possible to reliably prevent the gas released from the wastewater from leaking into the atmosphere, so that a closed system of 1,4-dioxane treatment can be constructed more reliably.

According to the present invention, in the biological treatment of 1,4-dioxane-containing wastewater using 1,4-dioxane-decomposing bacteria, the problem of the release of 1,4-dioxane into the atmosphere can be solved by a simple It is possible to effectively solve the problem.

1 is a sectional view for explaining a first embodiment of an apparatus for treating 1,4-dioxane-containing wastewater according to the present invention.
2 is a cross-sectional view for explaining a modification of the first embodiment.
3 is a cross-sectional view for explaining a second embodiment of the apparatus for treating 1,4-dioxane-containing wastewater of the present invention.
4 is a sectional view for explaining a third embodiment of the apparatus for treating wastewater containing 1,4-dioxane according to the present invention.
5 is a cross-sectional view for explaining a fourth embodiment of the apparatus for treating 1,4-dioxane-containing wastewater of the present invention.
Fig. 6 is an explanatory diagram of steps for producing a globally immobilized carrier containing 1,4-dioxane-degrading bacteria.
7 is a graph showing the removal rate of 1,4-dioxane from wastewater by air aeration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the method and apparatus for treating 1,4-dioxane-containing wastewater according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]

Fig. 1 shows an apparatus 10 for treating wastewater containing 1,4-dioxane according to the first embodiment of the present invention. The apparatus (10) for treating 1,4-dioxane-containing wastewater mainly comprises aeration means for air-aeration of wastewater containing 1,4-dioxane, Dioxane-decomposing bacteria and bringing the wastewater into contact with the 1,4-dioxane-decomposing bacteria while air-wasting the wastewater; and a gas treatment apparatus (12) And returning means (14) for returning the biological sample to the biological treatment tank (12).

The biological treatment tank 12 is formed as a closed ceiling surface 12A and an exhaust port 13 is provided on the ceiling surface 12A. A raw water pipe 16 of wastewater is connected to the biological treatment tank 12 and an aeration pipe 18 is provided at the bottom of the biological treatment tank 12, Is connected to the blower 20. By this, the wastewater containing 1,4-dioxane introduced into the biological treatment tank 12 is aerated and brought into an aerobic state. A DO measuring instrument 22 is installed in the wastewater of the biological treatment tank 12 and the DO measuring instrument 22 is connected to the aeration amount controller 24 by a signal cable or radio. The aeration controller 24 sets the DO in the wastewater to a range of 2.0 to 6.0 mg / L, more preferably 3.0 to 5.0 mg / L, in accordance with DO (dissolved oxygen demand) in the wastewater by the DO measuring device 22, L < / RTI > Further, the control means as claimed in the claims is implemented by the DO measuring device 22 (DO measuring means) and the aeration amount controller 24.

A trough 26 is provided on the opposite side of the raw water pipe 16 from the upper portion of the biological treatment tank 12 and the treated water treated in the biological treatment tank 12 is discharged from the treated water discharge port 28 And flows out to the trough 26. The treated water outlet 28 is formed below the liquid level of the biological treatment tank 12 and is sealed by the treated water that has been poured into the trough 26. This prevents the gas discharged from the wastewater from leaking from the treated water outlet 28 to the outside by the air aeration.

In the biological treatment tank 12, there is contained at least 1,4-dioxane-decomposing bacteria which decompose 1,4-dioxane, and the 1,4-dioxane-decomposing bacteria are 1,4-dioxane- Decomposes oxalic acid. Here, " having at least 1,4-dioxane decomposing bacteria " means to avoid misunderstanding that only 1,4-dioxane decomposing bacteria are present, and other bacteria may coexist.

As a seed sludge containing 1,4-dioxane decomposing bacteria, a plant handling 1,4-dioxane (for example, a plant for producing 1,4-dioxane, A production plant for producing an alkyl ether), a sludge of a wastewater treatment plant for treating the plant wastewater, and the like. However, even when the sludge is put into the biological treatment tank 12 as it is, the bacterial number concentration of the 1,4-dioxane-degrading bacteria is low and sufficient activity can not be exerted. Description of the isolation and cultivation of 1,4-dioxane will be described later.

When 1,4-dioxane-decomposing bacteria are used as inclusion-immobilized immobilized carriers as described later, the 1,4-dioxane decomposition efficiency is improved and the 1,4-dioxane concentration in the wastewater can be maintained at a low concentration . Therefore, the amount of 1,4-dioxane discharged from the wastewater by air aeration can be greatly reduced. Therefore, in the case of the immobilizing immobilization support, it is also possible to adopt a mode in which the rebounding means 14 is not used (not shown).

A returning means 14 for returning the gas discharged from the wastewater to the biological treatment tank 12 by air-aerating the wastewater by the sparger 18 is provided above the liquid level of the biological treatment tank 12, A sprinkling pipe 14A is installed.

The scrubbing apparatus comprises a water spray pipe 14A and a supply pipe 14B for supplying scrubbing water to the water spray pipe 14A. It is preferable that a plurality of water spray pipes 14A are provided so as to cover the entire liquid surface. In this case, it is also preferable to form the mist layer above the liquid level by spraying the scrubbing water from the water spray pipe 14A in a mist shape. As the scrubbing water, tap water and industrial water can be used, but it is more preferable to use treated water treated in the biological treatment tank 12. 2, a water pump 14C is provided at the tip of the supply pipe 14B connected to the water spray pipe 14A and the water pump 14C is connected to the trough 26 ).

Next, a treatment method for removing 1,4-dioxane from wastewater using the apparatus 10 for treating wastewater containing 1,4-dioxane as described above will be described.

The wastewater supplied from the raw water pipe 16 to the biological treatment tank 12 comes into contact with the 1,4-dioxane decomposing bacteria under an aerobic condition by the air aeration by the worm 18. By this, the 1,4-dioxane contained in the wastewater is decomposed and treated.

The 1,4-dioxane decomposing bacteria used in the present invention are aerobic bacteria. In addition, 1,4-dioxane in the gas discharged from the wastewater is returned to the biological treatment tank 12 again, so that the total amount of 1,4-dioxane in the wastewater and the gas hardly changes. Therefore, from the viewpoint of decomposing and removing 1,4-dioxane from wastewater, it is easy to think of a direction for improving the decomposition efficiency of 1,4-dioxane which is an aerobic microorganism by increasing the amount of air bubbles.

However, the present inventors have obtained the following findings. That is, when the air-blowing amount is too large, the time for which 1,4-dioxane is present in the gas and is not decomposed is longer than the time for contacting 1,4-dioxane-decomposing bacteria in the wastewater, It gets worse. On the other hand, if the air-blowing amount is too small, the 1,4-dioxane-decomposing bacteria can not sufficiently consume oxygen and the 1,4-dioxane load in the wastewater becomes too large. The decomposition efficiency of the oxane is deteriorated.

Therefore, by controlling the amount of 1,4-dioxane in the wastewater and the amount of 1,4-dioxane in the gas released from the wastewater by controlling the aeration amount of the air-aeration, the 1,4- The decomposition efficiency of dioxane can be increased.

Here, a test result obtained by examining the relationship between the air bubble amount and the decomposition efficiency using the apparatus shown in Fig. 2 will be described. In the test, the amount of 1,4-dioxane discharged from the discharge port 13 and the amount of 1,4-dioxane discharged from the treated water when the air bubble amount is changed without operating the return means 14 (scrubbing apparatus) And how the concentration changes.

Using a reaction tank (biological treatment tank) having an effective volume of 1 L, 100 mL (10% filling ratio) of a collective immobilized carrier immobilized with 1,4-dioxane decomposing bacteria was charged into the reaction tank. The temperature of the water was adjusted to 25 ° C and sodium hydroxide was automatically supplied by a pH controller so that the pH became 7.0.

Then, the DO value (dissolved oxygen) in the reaction tank is varied by controlling the air bubble amount, and the concentration of 1,4-dioxane in the treated water at that time and the amount of 1,4- did.

As a result, when the DO value in the reaction tank was in the range of 2 to 6 mg / L, the biological reaction in the reaction tank became favorable, and the 1,4-dioxane concentration in the treated water was about 10 mg / L.

However, if the DO value is less than 2 mg / L, the inclusion immobilization support does not flow in the reaction tank due to the lack of aeration amount, and stirring (stirring) becomes incomplete. As a result, the contact efficiency between the 1,4-dioxane-containing water (water) and the carrier to which the 1,4-dioxane-decomposing bacteria are entrapped is poor and the 1,4-dioxane concentration in the treated water is 20 mg / Of the total amount of the sample.

When the DO value exceeds 6 mg / L, the concentration of 1,4-dioxane in the treated water does not change at about 10 mg / L, but the amount of 1,4-dioxane in the reaction tank is rapidly increased , It was confirmed that the DO value was increased to 1.5 times or more as compared with when the DO value was 6 mg / L.

From this result, it is preferable that the air bubble amount is in the range of 2.0 to 6.0 mg / L when viewed from the DO value of the reaction tank (biological treatment tank), more preferably from 3.0 to 5.0 mg / L Range, it is possible to obtain a high decomposition efficiency.

However, 1,4-dioxane is liable to be released from wastewater by an aeration, and the release rate of the amount of 1,4-dioxane is 30% or more, and in many cases, it is about 70%. However, due to the problem of air pollution, it is not possible to let the released gas escape to the atmosphere. Here, the release rate of 30% means that 30% of the 1,4-dioxane in the wastewater before the air-aeration is discharged from the wastewater by air aeration.

Therefore, in the present invention, a plurality of spray pipes 14A are provided above the liquid level of the biological treatment tank 12, and the gas discharged from the wastewater is scrubbed by the scrubbing water sprinkled from the spray pipe 14A . By this, the water-soluble 1,4-dioxane is absorbed into the scrubbing water, and the scrubbing water that has absorbed 1,4-dioxane is poured down onto the surface of the biological treatment tank 12. Thereby, 1,4-dioxane in the scrubbing water is decomposed in the biological treatment tank 12.

In this case, tap water or industrial water can be used as the scrubbing water as shown in Fig. 1. However, as shown in Fig. 2, the use of the treated water treated in the biological treatment tank 12 as the scrubbing water More preferable. By doing so, the water retention time in the biological treatment tank 12 is not increased, so that the hydraulic retention time is stabilized and the decomposition efficiency of 1,4-dioxane can be kept high.

Thus, according to the treatment apparatus 10 for treating 1,4-dioxane-containing wastewater of the first embodiment, in the biological treatment of 1,4-dioxane-containing wastewater using 1,4-dioxane decomposing bacteria, The problem of the atmospheric release of 1,4-dioxane can be effectively solved by a simple constitution which does not require a special decomposition apparatus.

Next, the isolation and culture of 1,4-dioxane-degrading bacteria will be described.

<Isolation and culture of 1,4-dioxane-degrading bacteria>

As described above, the 1,4-dioxane-degrading bacteria are preferably cultured in advance. Since the growth rate of the 1,4-dioxane-degrading bacteria is very slow in the culture of the 1,4-dioxane-degrading bacteria, it is necessary to prevent other microorganisms from being mixed in the isolation step so as not to preferentially grow. In the culturing step, it is important to give organic matter to the 1,4-dioxane-degrading bacteria to promote the proliferation of the isolated 1,4-dioxane-degrading bacteria. Therefore, in the isolation step, an inorganic medium containing only 1,4-dioxane is used as an organic substance, and an organic medium mainly containing organic substances other than 1,4-dioxane is used in the culturing step.

That is, in the isolation step, first, 100 to 500 mL of the medium supplemented with 1,4-dioxane so as to have a concentration of 10 to 100 mg / L is added to the inorganic medium, (Sludge collected from wastewater treatment process of wastewater containing 1,4-dioxane) is added in an amount of about 500 to 20000 mg / L, followed by concentration. The integrated culture is preferably carried out under the condition of 20 to 30 DEG C for about 1 to 3 months. The presence of 1,4-dioxane-degrading bacteria can also be confirmed by measuring the change in 1,4-dioxane concentration in the medium. At the stage when the reduction rate of 1,4-dioxane concentration exceeds 50%, it is preferable to terminate the integrated culture. The concentration of 1,4-dioxane in the medium can be measured by a known method (Abe Akemi, Environmental Chemistry, vol.7, No.1, p95-100 (1997)).

After completion of the integrated culture, the inorganic culture medium is allowed to stand in a stationary culture medium containing agar (agar) at 10 to 15% at a constant temperature of 20 to 35 ° C. After confirming the formation of colonies after the stationary culture, the 1,4-dioxane-degrading bacteria can be isolated.

The inorganic substance constituting the inorganic medium is not particularly limited, but inorganic salts (for example, K ₂ HPO ₄ , (NH ₄ ) ₂ SO ₄ , MgSO ₄ .7H ₂ O, FeCl ₃ , CaCl ₂ , NaCl) Do.

In the next culture, the 1,4-dioxane-degrading bacteria isolated as described above are cultured in an organic medium containing an organic substance as a main component. As organic substances, CGY medium, specifically, readily degradable organic substances such as peptone, meat extract, glycerin, casitone, yeast extract and the like are preferable. The organic material may include 1,4-dioxane. Since the activity of the 1,4-dioxane-degrading bacteria is the highest at about 27 캜, the culture temperature is preferably 27 캜, and the water temperature is preferably about 15 캜 to 35 캜, more preferably 20 to 30 캜 . The incubation time is preferably about 5 to 30 days.

The 1,4-dioxane-decomposing bacterium is difficult to proliferate when excess amount of 1,4-dioxane is given in a small number of bacteria, while if 1,4-dioxane is not given at all, . Therefore, it is preferable to give an organic substance other than 1,4-dioxane at the initial stage of culture and to give 1,4-dioxane at the middle stage and the late stage of cultivation in which the number of bacteria of 1,4-dioxane decomposing bacteria has increased to some extent . That is, organic substances other than 1,4-dioxane mainly function to promote the proliferation of 1,4-dioxane-decomposing bacteria, and 1,4-dioxane mainly functions as 1,4-dioxane decomposing bacteria Maintain or improve the degradative activity. The addition of 1,4-dioxane is preferably carried out when the number of bacteria of 1,4-dioxane-degrading bacteria is 1 x 10 ⁴ cells / mL or more. The amount of 1,4-dioxane to be added is 1 to 1000 mg / L, preferably 10 to 200 mg / L, based on the organic medium. This is because if 1,4-dioxane is less than 1 mg / L, the effect of resurfacing, maintaining or improving the decomposition activity of the 1,4-dioxane-decomposing bacteria becomes small. When the added concentration of 1,4-dioxane exceeds 1000 mg / L, the 1,4-dioxane-degrading bacteria are inactivated due to the toxicity of 1,4-dioxane, Mg / L is preferable. When the amount of 1,4-dioxane is more than 200 mg / L, the decomposition activity is not changed any more, and even when it is 1000 mg / L, it is about the same as when it is 200 mg / L. In order to dispose of the medium in a harmless condition, it is necessary to make the concentration of 1,4-dioxane in the medium as low as possible. Therefore, the addition of 1,4-dioxane is preferably carried out in small amounts depending on the number of bacteria and the degree of activity of the 1,4-dioxane-degrading bacteria. From the initial stage of the culture, 1,4-dioxane may be contained in the organic medium. In this case, the content of 1,4-dioxane may be the same as that described above.

The cultivated 1,4-dioxane-decomposing bacteria can be used as it is put into the biological treatment tank 12 as it is. However, in order to put it into the wastewater more densely, 1,4-dioxane decomposing bacteria are immobilized on the carrier material Is preferably used. Examples of immobilizing methods include a method (entrapping immobilization carrier) in which 1,4-dioxane-degrading bacteria that have been cultured in a hydrous gel are entrapped and flowed in a tank, a 1,4-di Dioxane-decomposing bacteria cultured on a fixed bottom, and a method of adhering and fixing the oxacillin-degrading bacteria in a bath (adhering immobilization support), and the like.

Pseudonocardia dioxanivorans have been reported as 1,4-dioxane-degrading bacteria and can be purchased from the American Type Culture Collection (ATCC) for use in degradation tests (1,4-dioxane biodegradation at low temperatures in Arctic groundwater samples Water Research, Volume 44, Issue 9, 2010, Pages 2894-2900). Further, the isolation of 1,4-dioxane-degrading bacteria, the culture conditions and the culture conditions can be carried out by the method described in Japanese Unexamined Patent Application Publication No. 2008-306939.

[Second Embodiment]

Fig. 3 shows an apparatus 10 for treating wastewater containing 1,4-dioxane according to the second embodiment of the present invention. This treatment apparatus 10 is a modification of the returning means 14 for returning 1,4-dioxane in the gas discharged from the wastewater to the biological treatment tank 12. The same reference numerals are given to the same components and members as those described in the first embodiment, and a description thereof will be omitted.

The biological treatment tank 12 in the second embodiment is formed in a closed structure in which the top surface is not opened, and a head space 30 in which the gas released by the air aeration is accumulated above the liquid level is formed. Also, the treated water outlet 28 is formed in a water-sealed structure similarly to the above.

The returning means 14 includes a pipe 32 connecting the head space 30 and the blower 20 and a pipe 32 provided in the pipe 32 for supplying a gas, And a buffer tank 36 provided between the blower fan 34 and the blower 20. The blower fan 34 is provided with a blower fan 34,

As a result, the gas that has become lodged in the head space 30 is sent to the blower 20 via the buffer tank 36 by the blowing fan 34, did. In this case, it is preferable that the air volume blown from the blowing fan 18 is larger than the air blowing to the blowing fan 34. As a result, when the buffer tank 36 becomes negative pressure, the check valve 38 is opened, and the atmosphere is replenished in the buffer tank 36.

1,4-dioxane is water-soluble and 1,4-dioxane is dissolved in the wastewater by aerating a gas containing 1,4-dioxane into the wastewater. Due to this, in the biological treatment tank 12, 1,4-dioxane and 1,4-dioxane-decomposing bacteria in the gas come into contact with each other, Oxane can be effectively removed.

Thus, the same effect as that of the first embodiment can be obtained with respect to the treatment apparatus 10 for treating 1,4-dioxane-containing wastewater of the second embodiment.

[Third embodiment]

4 shows an apparatus 10 for treating wastewater containing 1,4-dioxane according to the third embodiment. This treatment apparatus 10 is another example in which the return means 14 for returning 1,4-dioxane in the gas discharged from the wastewater to the biological treatment tank 12 is changed to another mode. The same reference numerals are given to the same components and members as those described in the first and second embodiments, and a description thereof will be omitted.

4, the biological treatment tank 12 is provided with a lid member 40 that covers the biological treatment tank 12, thereby forming a head space 30 above the liquid level. An opening 42 into which the tip of the raw water pipe 16 is inserted into the head space 30 is formed at the upper side of one side of the biological treatment tank 12 and the other end of the biological treatment tank 12 And an overflow hole 44 through which the process water is discharged is formed in an upper portion of the side of the end surface. That is, in the third embodiment, the head space 30 and the outside are communicated with each other through the opening 42 and the through-hole 44.

A scrubbing tower 46 of a closed structure is provided above the biological treatment tank 12 and a scrubbing water pipe 46A of scrubbing water is provided at an upper position in the scrubbing tower 46. The water storage section 46B of the scrubbing water is provided at a lower position in the scrubbing tower 46. The water storage section 46B and the water spray pipe 46A are connected to the circulation pipe 46D via the circulation pump 46C, Respectively. Further, a supply pipe 46E for supplying the scrubbing water is connected to the water storage portion 46B. Further, an exhaust port 13 is provided on the top surface of the scrubbing tower 46.

The gas introduction pipe 46F extending from the side of the scrubbing column 46 to the side between the water spray pipe 46A and the water reservoir 46B passes through the lid member 40 of the biological treatment tank 12, And extends to the space 30, and a blowing fan 46G is provided in the gas introduction pipe 46F. The return pipe 46H extending downward from the bottom portion 46B of the scrubbing column 46 extends through the lid member 40 of the biological treatment tank 12 and is extended to the head space 30 , And the return pipe 46H is provided with a flow rate adjusting valve 46J.

This causes the gas that is trapped in the head space 30 of the biological treatment tank 12 to be sent to the scrubbing tower 46 via the gas introducing pipe 46F by the blowing fan 46G, The scrubbing process is carried out by the scrubbing water which can be sprinkled from the spray nozzle. Then, 1,4-dioxane in the gas is absorbed in the scrubbing water, and the scrubbing water absorbing 1,4-dioxane is accumulated in the reservoir 46B. At the start of the operation of the scrubbing tower 46, the scrubbing water is previously stored in the reservoir 46B from the supply pipe 46E. As the scrubbing water supplied from the supply pipe 46E to the reservoir portion 46B, tap water, industrial water, and treated water in the biological treatment tank 12 can be used.

A part of the scrubbing water remaining in the reservoir portion 46B is dropped by gravity through the return pipe 46H and returned to the biological treatment tank 12 in accordance with the opening degree of the flow regulating valve 46J And 1,4-dioxane in the scrubbing water is subjected to biological treatment.

The same amount of scrubbing water as the scrubbing water returned to the biological treatment tank 12 is replenished from the supply pipe 46E to the reservoir portion 46B. This can prevent the 1,4-dioxane concentration in the scrubbing water from rising and the scrubbing efficiency from being lowered.

Therefore, the same effects as in the first embodiment can be obtained for the apparatus 10 for treating wastewater containing 1,4-dioxane according to the third embodiment.

[Fourth Embodiment]

Fig. 5 shows an apparatus 10 for treating wastewater containing 1,4-dioxane according to the fourth embodiment. The treatment apparatus 10 has a water-sealed structure in which a wastewater supply port 50 and a treated water discharge port 54 to the biological treatment tank 12 are integrally fixed with 1,4-dioxane decomposing bacteria, The immobilization support 56 is put into the biological treatment tank 12 after being accumulated and cultured. The same reference numerals are given to the same elements and members as those described in the first to third embodiments, and a description thereof will be omitted.

An inlet trough 48 for supplying wastewater to the biological treatment tank 12 is provided and a wastewater supply port 50 for communicating the inlet trough 48 and the biological treatment tank 12 is provided, Is formed below the liquid level of the treatment tank (12). An outlet trough 52 for discharging the treated water in the biological treatment tank 12 is provided and a treated water outlet 54 communicating the outlet trough 52 and the biological treatment tank 12 is connected to the biological treatment tank 12). Thus, the waste water supply port 50 is sealed with wastewater poured into the inlet trough 48, and the treated water outlet 54 is sealed with the deionized water to the outlet trough 52. In addition, in the biological treatment tank 12, the inclusion immobilization support 56 in which 1,4-dioxane decomposing bacteria are cultured and the number of bacteria is increased is introduced. The manufacturing method of the immobilizing immobilization support 56 will be described later. Since the biological treatment tank 12 is sealed and the air sent from the blower 20 can be conveyed to the scrubbing tower 46 through the pipe 46F, the fan 46G is not necessarily required.

According to the apparatus 10 for treating wastewater containing 1,4-dioxane according to the fourth embodiment configured as described above, the concentration of 1,4-dioxane in the treated water can be remarkably reduced compared to the first to third embodiments And the amount of 1,4-dioxane released by air aeration can be reduced.

Next, a method for producing a globally immobilized carrier 56 containing 1,4-dioxane-degrading bacteria will be described.

&Lt; Process for producing a globally immobilized carrier containing 1,4-dioxane-degrading bacteria >

1,4-dioxane-decomposing bacteria were immobilized by the following method.

Fig. 6 is a view for explaining the flow of the manufacturing method of the immobilizing immobilizing support 56. Fig. As shown in Fig. 6, first, a mixed solution obtained by mixing the immobilized material such as a prepolymer material and the culture liquid of the isolated 1,4-dioxane-degrading bacterium and adjusting the pH to around neutral (6.5 to 8.5) is prepared . In the later examples, a polyethylene glycol-based material was used as the immobilizing material.

Subsequently, a polymerization initiator (potassium persulfate was used in the later example) was added to the mixed solution, stirred and immediately gelated (polymerized) in a sheet form or a block form. The polymerization temperature is preferably 15 to 40 占 폚, more preferably 20 to 30 占 폚. The polymerization time is preferably 1 to 60 minutes, more preferably 10 to 60 minutes. Then, the gelled sheet or block is cut into a predetermined size (in the latter embodiment, a cubic shape with a corner of approximately 3 mm), whereby the inclusion immobilization support 56 can be obtained. The initial immobilized concentration of 1,4-dioxane-degrading bacteria was 1 × 10 ⁷ cells / mL.

The inorganic immobilizing carrier 56 thus produced can be produced by using an inorganic wastewater containing 1,4-dioxane at a water temperature of 25 ° C and a 1,4-dioxane load of 1 to 8 kg- (Dioxan) / m 3 · When the culture is carried out continuously for about one month under the carrier / day (day), the decomposition activity of 1,4-dioxane per carrier is 7.1 kg- (Dioxan) / m3 · carrier. In the test A of the later-described example, the immobilizing immobilization support 56 thus produced was used.

In addition, the method of manufacturing the inclusion immobilization pellets 56 is not limited to the above-described method, and a tube forming method, a dropping granulation method, or the like may be employed.

It is needless to say that the collective immobilization pellets 56 are put into the processing apparatus 10 shown in Fig. 5, but the collective immobilization pellets 56 can also be put into the processing apparatus 10 shown in Figs.

The processing apparatuses 10 shown in the first to fourth embodiments may be suitably combined and installed in multiple stages. This can solve the problem that 1,4-dioxane is released to the atmosphere because the closed system of 1,4-dioxane treatment can be continuously formed, It is possible to lower the 1,4-dioxane concentration in the treated water to a very low level.

Example

[Test A (no scrubbing, no 1,4-dioxane decomposing carrier)]

In Test A, a device in which the scrubbing device (refeed means 14) was removed from the treatment device 10 shown in Fig. 1 was formed (not shown). The 1,4-dioxane concentration in the treated water and the amount of 1,4-dioxane released into the air from the wastewater by the air aeration were examined in this apparatus when 1,4-dioxane-containing wastewater was treated .

Test A used inorganic synthetic wastewater having a concentration of 1,4-dioxane of 500 mg / L. In addition. A plastic carrier having a biofilm formed by attaching activated sludge which had been treated for a long period of wastewater from a chemical plant containing 1,4-dioxane to a biological treatment tank having a reaction volume of 1 L was charged so as to have an apparent filling rate of 40%. Then, the inorganic synthetic wastewater was supplied to the biological treatment tank, and water was continuously passed therethrough so that the residence time (HRT) was 24 hours (1 L / day). The water temperature was set at 25 ° C. The 1,4-dioxane load at this time is 0.5 g / day. Also, the air bubble amount of the biological treatment tank was 0.8 L / min (about 4.0 mg / L as DO).

As a result, the 1,4-dioxane concentration in the treated water was 230 mg / L. At this time, the concentration of 1,4-dioxane in the gas discharged from the wastewater by the air aeration was measured at the position of the exhaust port, and the amount of 1,4-dioxane produced per day was calculated from the air bubble amount. As a result, / Day.

This is because the 1,4-dioxane load in test A is 0.5 g / day, so that approximately one-half of 1,4-dioxane is formed in the air. Therefore, it was found that the plastic carrier on which the biofilm was formed had almost no decomposition activity of 1,4-dioxane.

[Test B (with scrubbing, without 1,4-dioxane-decomposing carrier)]

Test B was conducted using the treatment apparatus 10 shown in Fig. 2, which was configured to spray the treated water from the biological treatment tank 12 from the spray pipe 14A of the scrubbing apparatus (the return means 14). The other conditions are the same as in Test A.

As a result, the 1,4-dioxane concentration in the treated water became 360 mg / L, which was higher than the treated water in Test A. At this time, the concentration of 1,4-dioxane in the gas discharged from the wastewater by the air aeration was measured, and the amount of 1,4-dioxane-based acid in one day was calculated from the air bubble amount, and was found to be 0.12 g / day.

This is because, as in Test B, the gas discharged from the wastewater is scrubbed, the 1,4-dioxane in the gas is absorbed into the scrubbing water and returned to the biological treatment tank 12, whereby the scrubbing water is not supplied from the outside, The amount of 1,4-dioxane produced in the test can be reduced to half of that of Test A.

[Test C (with external scrubbing, no 1,4-dioxane decomposing carrier)]

In the test C, the wastewater supply port 50 and the treated water discharge port 54 of the treatment apparatus 10 were constructed using the treatment apparatus 10 shown in Fig. In the treatment apparatus 10 shown in Fig. 5, the inclusion immobilizing carrier 56 of 1,4-dioxane-degrading bacteria was put in. In Test C, an biofilm of a plastic carrier was used in the same manner as in Tests A to B. The other conditions are the same as in Test A.

As a result, the 1,4-dioxane concentration in the treated water became 440 mg / L, which was higher than the treated water in Test B. However, at the position of the treated water outlet 54, the amount of 1,4-dioxane-based acid was calculated to be 0.03 g / day, which was further reduced than in Test B.

This is because the water discharged from the wastewater flows into the wastewater supply port 50 and the treated water discharge port 54 (see FIG. 5) by making the water supply port 50 and the treated water discharge port 54 of the biological treatment tank 12, And unnecessary air does not enter the wastewater supply port 50 and the treated water discharge port 54, thereby improving the efficiency of the scrubbing process.

[Test D (without scrubbing, with 1,4-dioxane decomposing carrier)]

In Test D, a treatment in which a carrier in which 1,4-dioxane decomposing bacteria were immobilized by entrapment and immobilization was introduced into a biological treatment tank using a treatment apparatus (not shown) having no scrubbing apparatus (returning means 14) Apparatus. In Test D, 1,4-dioxane-degrading bacteria were isolated and used by the method described in Japanese Unexamined Patent Application Publication No. 2008-306939. The 1,4-dioxane-degrading bacteria may also be purchased from the American Type Culture Collection (ATCC). The inclusion immobilization carrier of 1,4-dioxane-decomposing bacteria was a cube of 3 mm corners. That is, the initial immobilized concentration of 1,4-dioxane-degrading bacteria in the integrated culture was fixed to polyethylene glycol-based immobilizing material as a carrier at 1 × 10 ⁷ cells / mL. The obtained immobilized carrier was immersed in an organic wastewater containing 1,4-dioxane at a water temperature of 25 占 폚, a 1,4-dioxane load of 2 to 9 kg (dioxin) / m3, Followed by continuous culture. At this time, the decomposition activity of 1,4-dioxane per carrier was 5.0 kg (dioxin) / m 3 · carrier.

Then, the obtained immobilized carrier was charged into a biological treatment tank so as to have a volume of 100 mL (filling rate: 10%). The other conditions are the same as in Test A.

As a result, the concentration of 1,4-dioxane in the treated water was 10 mg / L, which was significantly reduced as compared with the above Tests A to C. Further, the amount of 1,4-dioxane-based acid was calculated, and it was reduced to 0.01 g / day in spite of the absence of a scrubbing apparatus, and was significantly reduced from 0.24 g / day in Test A.

This is due to the fact that the decomposition efficiency of 1,4-dioxane in the wastewater is remarkably improved by introducing a collectively immobilized carrier in which 1,4-dioxane decomposing bacteria are integrated and cultivated in the biological treatment tank as in Test D do. That is, it is considered that the 1,4-dioxane decomposition efficiency is improved and the 1,4-dioxane concentration in the wastewater is maintained at a low concentration, whereby the amount of 1,4-dioxane released from the wastewater by air aeration is considerably reduced.

[Test E (Relationship between 1,4-dioxane concentration and removal rate in wastewater]

In Test E, it was examined how the removal rate of 1,4-dioxane released by the air aeration and removed from the wastewater changes with the concentration of 1,4-dioxane in the wastewater to be aeration.

Test E was carried out by using the biological treatment tank used in Test A to determine the concentration of 1,4-dioxane contained in the inorganic synthetic wastewater when air-aerated at a constant condition of 0.75 L / The concentration of 1,4-dioxane in the discharged gas was examined. However, the biological treatment tank was carried out without the inclusion of immobilized carrier. The residence time (HRT) was set to 12 hours.

The concentration of 1,4-dioxane in the inorganic synthetic wastewater supplied to the test is as follows.

Sample 1 (S-1): 2 mg / L

Sample 2 (S-2): 9 mg / L

Sample 3 (S-3): 75 mg / L

Sample 4 (S-4): 100 mg / L

Sample 5 (S-5): 360 mg / L

Sample 6 (S-6): 500 mg / L

The results are shown in Fig. As can be seen from the results in Fig. 7, it was found that 20 to 40% (about 30% on average) of 1,4-dioxane in the wastewater was removed by air aeration, regardless of the 1,4- Can be removed. Therefore, for example, in a biological treatment tank of an actual apparatus scale containing 1,4-dioxane-degrading bacteria, when the concentration of 1,4-dioxane in the tank is reduced to only 100 g / m 3, The residence time of about 30 g of 1,4-dioxane per day is released to the atmosphere by air aeration.

On the other hand, if the concentration of 1,4-dioxane in the tank can be lowered to 1 g / m 3, if it is treated with a residence time of 1 m 3 / day, only about 0.3 g of 1,4-dioxane per day It is not discharged, and the emission amount can be remarkably reduced.

That is, in order to suppress the release of 1,4-dioxane by air-aeration, it is very important to lower the 1,4-dioxane concentration in the bath as much as possible. For this purpose, as can be seen from the results of Test E, the decomposition activity of 1,4-dioxane in the biological treatment tank is increased, and the concentration of 1,4-dioxane in the wastewater in the biological treatment tank is always maintained at low level .

[Test F (with scrubbing, with 1,4-dioxane decomposing carrier)]

In the test F, the whole immobilization carrier 56 (see Fig. 5) in which the 1,4-dioxane decomposing bacteria were immobilized in the biological treatment tank 12 (see Fig. 5) Filling rate: 10%). The procedure was the same as that of Test B except that the inclusion immobilization support 56 in the biological treatment tank 12 was different.

As a result, the concentration of 1,4-dioxane in the treated water was 10 mg / L. This indicates that the 1,4-dioxane concentration could be drastically reduced from 360 mg / L, which is the result of Test B, by the effect of the carrier immobilizing 1,4-dioxane-degrading bacteria, .

Also, the amount of 1,4-dioxane in the gas exhausted from the exhaust port 13 was only 0.004 g / day, and the amount of 1,4-dioxane discharged to the outside of the system was greatly reduced.

[Test G (with external scrubbing, with 1,4-dioxane degrading carrier)]

In test G, a whole immobilization carrier 56 (see FIG. 5) in which 1,4-dioxane-degrading bacteria were immobilized was charged in a biological treatment tank 12 at 100 mg / L (10% filling ratio). The procedure was the same as that of Test C except that the inclusion immobilization support 56 in the biological treatment tank 12 was different.

As a result, the concentration of 1,4-dioxane in the treated water was 10 mg / L, which was equivalent to the tests D and F. As a result of measuring the amount of 1,4-dioxane discharged from the exhaust port 13, the amount of 1,4-dioxane formed was 0.004 g / day equivalent to that of Test F, The amount of oxalic acid could be greatly reduced.

10: Treatment device for wastewater containing 1,4-dioxane 12: Biological treatment tank
13: exhaust port 14: returning means
14A: Sprinkler pipe 14B: Supply pipe
14C: Submersible pump 16: Raw water piping
18: Blower 20: Blower
22: DO Meter 24: Aperture Controller
26: trough 28: treated water outlet
30: headspace 32: piping
34: blower fan 36: buffer tank
38: check valve 40: cover member
42: aperture 44:
46: scrubbing tower 46A: water spray tube
46B: reservoir part 46C: circulation pump
46D: circulation piping 46E: supply piping
46F: gas introduction pipe 46G: blowing fan
46H: Return piping 46J: Flow regulating valve
48: inlet trough 50: waste water supply port
52: outlet trough 54: treated water outlet
56: Comprehensive immobilization carrier

Claims (13)

A method for treating wastewater containing 1,4-dioxane,
Dioxane-decomposing bacteria which decompose 1,4-dioxane, and a biological treatment step of bringing the wastewater into contact with the treated wastewater in the biological treatment tank while air-
And returning the 1,4-dioxane in the gas discharged from the wastewater to the biological treatment tank by the air aeration of the biological treatment tank,
In the recycling step, 1,4-dioxane in the gas is absorbed into the scrubbing water by scrubbing the gas discharged from the wastewater, and treated water in the biological treatment tank is used as the scrubbing water, Wherein the water is returned to the biological treatment tank. delete A method for treating wastewater containing 1,4-dioxane,
Dioxane-decomposing bacteria which decompose 1,4-dioxane, and a biological treatment step of bringing the wastewater into contact with the treated wastewater in the biological treatment tank while air-
And returning the 1,4-dioxane in the gas discharged from the wastewater to the biological treatment tank by the air aeration of the biological treatment tank,
Wherein the gas discharged from the wastewater is returned as the gas for the air-aeration in the biological treatment tank in the returning step. The method according to claim 1 or 3,
The method for treating 1,4-dioxane-containing wastewater according to claim 1, wherein in the biological treatment step, the dissolved oxygen demand (DO) in the wastewater by the air aeration is controlled to fall within a range of 2 to 6 mg / L. An apparatus for treating wastewater containing 1,4-dioxane,
Dioxane decomposing bacteria for decomposing the 1,4-dioxane and having aeration means for air-aeration of the wastewater, and the 1,4-dioxane decomposition bacteria A biological treatment tank,
And returning means for returning 1,4-dioxane in the gas released from the wastewater by the air aeration of the biological treatment tank to the biological treatment tank,
The above-
A pipeline connecting the aeration means with the head space formed by the closed structure of the biological treatment tank,
And a blowing fan installed in the pipe for sending a gas, which is stuck in the head space, to the aeration means. An apparatus for treating wastewater containing 1,4-dioxane,
Dioxane decomposing bacteria for decomposing the 1,4-dioxane and having aeration means for air-aeration of the wastewater, and the 1,4-dioxane decomposition bacteria A biological treatment tank,
And returning means for returning 1,4-dioxane in the gas released from the wastewater by the air aeration of the biological treatment tank to the biological treatment tank,
The above-
Dioxane in the gas is absorbed into scrubbing water by scrubbing the gas discharged from the wastewater, and the treated water in the biological treatment tank is used as the scrubbing water, and the scrubbing water is subjected to the biological treatment Wherein the scrubbing device is a scrubbing device which is returned to the scrubbing device. The method according to claim 5 or 6,
And a control means for controlling a balance between the amount of 1,4-dioxane in the wastewater and the amount of 1,4-dioxane in the gas discharged from the wastewater,
Wherein,
DO measurement means for measuring the dissolved oxygen demand in the wastewater,
And an aeration amount controller for adjusting the amount of air bubbles from the aeration means so as to obtain a predetermined dissolved oxygen demand amount based on the measurement result of the DO measurement means. delete 6. The method of claim 5,
The biological treatment tank may further comprise:
A lid member covering the biological treatment tank,
Wherein the biological treatment tank is provided with a supply port for supplying wastewater and a water-sealed structure formed at an outlet of the treated water treated in the biological treatment tank. The method according to claim 6,
The biological treatment tank may further comprise:
A lid member covering the biological treatment tank,
Wherein the biological treatment tank is provided with a supply port for supplying wastewater and a water-sealed structure formed at an outlet of the treated water treated in the biological treatment tank. delete delete delete

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