JP2015160202A - Method and apparatus for biological treatment of 1,4-dioxane-containing organic waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide method and apparatus for a biological treatment of 1,4-dioxane-containing organic waste water, by which 1,4-dioxane in waste water can be stably decomposition-treated in a shorter period of time while maintaining high activity of 1,4-dioxane decomposition bacteria.SOLUTION: A biological treatment method for 1,4-dioxane-containing organic waste water includes: a first treatment process of obtaining a first treatment solution 3 by treating 1,4-dioxane-containing organic waste water 1 in a first aeration tank 2 containing active sludge; a second treatment process of obtaining a second treatment solution 5 by loading the first treatment solution 3 into a second aeration tank 4 containing a microorganism carrier carrying microorganism for decomposing 1,4-dioxane and active sludge so as to decompose the 1,4-dioxane in the first treatment solution 3 by the microorganism carrier in the presence of the active sludge; a solid-liquid separation process of obtaining treatment water 7 and concentrated sludge 8 by subjecting the second treatment solution 5 to solid-liquid separation; and a return process of returning the concentrated sludge 8 into the first aeration tank 2.

Description

  The present invention relates to a biological treatment method and treatment apparatus for 1,4-dioxane-containing organic wastewater, and in particular, 1,4 such as wastewater from manufacturing plants for chemical products and semiconductors, leachate from landfills, sewage, etc. -It is related with the biological treatment method of 1, 4- dioxane containing organic wastewater which can biologically process the organic wastewater containing a dioxane using microorganisms, and its processing apparatus.

  1,4-dioxane is a substance suspected of having carcinogenicity, and has already been regulated so that the standard value thereof is 0.05 mg / L or less as a tap water standard and an environmental standard. As a wastewater standard, it was established in 2012 as 0.5 mg / L or less. As a generation source of 1,4-dioxane, by-products generated mainly in 1,4-dioxane production process, semiconductor industrial product production process using 1,4-dioxane as a solvent, chemical product production process, etc. Is mentioned.

  1,4-Dioxane is a biologically degradable substance. In conventional wastewater treatment facilities, biological treatment, coagulation treatment, sand filtration treatment, etc. are the main, and therefore, 1,4-dioxane removal effect is hardly obtained. As an effective treatment method capable of decomposing and removing 1,4-dioxane, ozone treatment, ozone and hydrogen peroxide treatment, accelerated oxidation treatment by a combination of ozone and ultraviolet treatment, so-called AOP treatment is known (for example, Patent Documents). 1 and 2).

  However, AOP treatment generally generates hydroxyl radicals with strong oxidizing power by an accelerated oxidation reaction centered on ozone, and decomposes organic matter in the water to be treated containing 1,4-dioxane. Therefore, in wastewater with a high concentration of organic matter, organic matter other than 1,4-dioxane is also decomposed, so that there is a problem that the required ozone injection amount and the amount of chemicals are increased and high treatment costs are required.

  In recent years, biological treatment methods that can be treated at a lower running cost than AOP treatment have been studied. For example, a method for treating 1,4-dioxane-containing treated water using a microorganism that decomposes 1,4-dioxane (hereinafter referred to as “1,4-dioxane-degrading bacteria”) is disclosed (for example, Patent Document 3 and 4).

JP-A-2005-103401 JP 2005-58854 A JP 2012-161737 A JP 2012-179590 A

  In the treatment methods described in Patent Documents 3 and 4, in order to stably maintain the activity of 1,4-dioxane-decomposing bacteria, 1,4-dioxane-degrading bacteria are cultured in advance before actually starting the treatment. To do. The cultured 1,4-dioxane degrading bacteria are entrapped and immobilized on a carrier and flowed into an aeration tank, whereby 1,4-dioxane is decomposed.

  However, the method using the entrapping immobilization support containing 1,4-dioxane degrading bacteria previously cultured as described in Patent Documents 3 and 4 requires time for the culture treatment, and the culture treated 1, Since further time is required to stabilize the processing apparatus by actually introducing 4-dioxane-degrading bacteria into the aeration tank, the processing time becomes longer.

  Furthermore, in the treatment methods described in Patent Documents 3 and 4, the cultured environment and the environmental conditions used for actual treatment are often different, and the activity of 1,4-dioxane-degrading bacteria is stabilized by changes in the environmental conditions. And may be difficult to maintain. For example, when the organic matter concentration of inflow wastewater greatly fluctuates, for example, when wastewater with a high biochemical oxygen demand (BOD) flows into the aeration tank, the decomposition activity of the entrapping immobilization support significantly decreases, In some cases, 1,4-dioxane cannot be stably treated.

  In view of the above problems, the present invention contains 1,4-dioxane that can stably decompose 1,4-dioxane in wastewater in a shorter time while maintaining high activity of 1,4-dioxane degrading bacteria. A biological treatment method for organic wastewater and a treatment apparatus therefor are provided.

  As a result of experimental studies using actual wastewater, the present inventors have found a microbial carrier for decomposing 1,4-dioxane when 1,4-dioxane-containing organic wastewater is treated in the second aeration tank. Coexist with activated sludge, proceed with 1,4-dioxane decomposition reaction in the wastewater in the presence of activated sludge and return the concentrated sludge concentrated from the treatment liquid obtained in the second aeration tank to the first aeration tank It was found that a biological treatment method of 1,4-dioxane-containing organic wastewater and a treatment apparatus thereof capable of stably decomposing 1,4-dioxane in wastewater in a shorter time can be obtained.

  The present invention completed on the basis of the above knowledge is, in one aspect, a first treatment step of obtaining a first treatment liquid by treating 1,4-dioxane-containing organic wastewater in a first aeration tank containing activated sludge. The first treatment liquid is introduced into a second aeration tank containing a microorganism carrier supporting microorganisms that decompose 1,4-dioxane and activated sludge, and the first treatment liquid is contained in the first treatment liquid by the microorganism carrier in the presence of activated sludge. A second treatment step for decomposing 1,4-dioxane to obtain a second treatment solution, a solid-liquid separation step for obtaining a treated water and concentrated sludge by solid-liquid separation of the second treatment solution, 1 is a biological treatment method of 1,4-dioxane-containing organic wastewater including a returning step of returning to an aeration tank.

  In one embodiment, the treatment method according to the present invention includes a dispensing step of dispensing a portion of 1,4-dioxane-containing organic waste water before supplying it into the first aeration tank and supplying it to the second aeration tank. Including.

  In another embodiment, the treatment method according to the present invention includes a dispensing and returning step of dispensing a part of the concentrated sludge before returning it to the first aeration tank and returning it to the second aeration tank.

  In still another embodiment of the treatment method according to the present invention, the microbial carrier includes a binding immobilization carrier in which a microorganism that decomposes 1,4-dioxane is adhered and fixed on the surface of the carrier.

  In still another embodiment of the treatment method according to the present invention, the first treatment step includes treatment at a BOD sludge load of the first aeration tank of 0.1 to 0.5 kg / kg / d, The treatment step includes treatment at a BOD sludge load of the second aeration tank of 0.1 kg / kg / d or less.

  In still another embodiment of the treatment method according to the present invention, a novel carrier is supplied into the second aeration tank, and the first treatment liquid is treated with a BOD sludge load of 0.05 kg / kg / d or less, The method further includes the step of attaching a microorganism that decomposes 4-dioxane in the second aeration tank, and depositing the grown microorganism on the surface of the new carrier.

  In another aspect of the present invention, a first aeration tank that obtains a first treatment liquid by decomposing organic matter in 1,4-dioxane-containing organic wastewater with activated sludge, and 1,4-dioxane in the presence of activated sludge. A second aeration tank that obtains a second treatment liquid by decomposing 1,4-dioxane in the first treatment liquid using a microorganism carrier that supports microorganisms that decompose dioxane, and a second treatment liquid is subjected to solid-liquid separation, and treated water And a solid-liquid separator for obtaining concentrated sludge, and a biological treatment apparatus for organic wastewater containing 1,4-dioxane comprising a concentrated sludge return line for returning the concentrated sludge from the solid-liquid separator to the first aeration tank.

  According to the present invention, 1,4-dioxane-containing organic wastewater that can stably decompose 1,4-dioxane in wastewater in a shorter time while maintaining high activity of 1,4-dioxane-degrading bacteria. The biological treatment method and the treatment apparatus thereof can be provided.

It is the schematic showing an example of the biological treatment flow which concerns on embodiment of this invention. It is the schematic showing the 1st modification of the biological treatment flow of FIG. It is the schematic showing the 2nd modification of the biological treatment flow of FIG. It is the schematic showing the conventional biological treatment flow.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments exemplify devices and methods for embodying the technical idea of the present invention. The technical idea of the present invention specifies the structure, arrangement, etc. of each device as follows. Not what you want.

(Biological treatment equipment)
As shown in FIG. 1, the water treatment apparatus according to the embodiment of the present invention decomposes the organic matter in 1,4-dioxane-containing organic waste water 1 (hereinafter also referred to as “raw water”) with activated sludge. The first aeration tank 2 for obtaining the treatment liquid 3 and the microorganism carrier carrying the microorganisms for decomposing 1,4-dioxane in the presence of activated sludge decompose the 1,4-dioxane in the first treatment liquid 3 for the first time. 2 The second aeration tank 4 for obtaining the treatment liquid 5, the solid-liquid separation device 6 for separating the second treatment liquid 5 into solid-liquid separation to obtain the treated water 7 and the concentrated sludge 8, And a concentrated sludge return line 11 for returning to the first aeration tank 2.

  The 1,4-dioxane-containing organic wastewater 1 is not particularly limited as long as it is a wastewater containing 1,4-dioxane. For example, wastewater from manufacturing plants such as chemical products and semiconductors, leachate from landfills, and sewage Organic wastewater containing 1,4-dioxane such as can be treated. The 1,4-dioxane concentration of the 1,4-dioxane-containing organic wastewater 1 is not limited to the following, but for example, wastewater having a 1,4-dioxane concentration of 10 to 400 mg / L can be suitably treated, More specifically, wastewater having a 1,4-dioxane concentration of 20 to 150 mg / L, more specifically 40 to 120 mg / L can be treated.

  A known aerobic biological treatment apparatus is used as the first aeration tank 2. Activated sludge is accommodated in the first aeration tank 2, and most easily decomposable organic substances, particularly BOD, in the 1,4-dioxane-containing organic wastewater 1 are decomposed and removed by the metabolism of microorganisms.

  For example, in the case where 1,4-dioxane-containing organic waste water 1 is supplied to the first aeration tank 2 at a rate of 100 to 300 L / d for treatment, the BOD sludge load of the first aeration tank 2 is 0.1 to 0.5 kg. / Kg / d, more preferably 0.2 to 0.4 kg / kg / d, and activated sludge suspended solids concentration (MLSS) 1000 to 8000 mg / L, more preferably 4000 to 5500 mg / L.

  The second aeration tank 4 contains a microbial carrier carrying 1,4-dioxane degrading bacteria for decomposing 1,4-dioxane. As 1,4-dioxane-degrading bacteria, known microorganisms used for wastewater treatment of 1,4-dioxane-containing organic wastewater 1 can be used. In particular, in the present embodiment, it is preferable to use a bond-immobilized carrier in which a microorganism that decomposes 1,4-dioxane is adhered and fixed on the surface of the carrier as the microorganism carrier. The “bound immobilization carrier” means a carrier on which microorganisms are immobilized by a binding immobilization method in which microorganisms gradually adhere or grow on the surface of the carrier. By using the bound immobilization carrier, the efficiency of transporting the substrate to the microorganism is increased, and an improvement in the reaction rate can be expected.

  Further, as will be described in detail in the biological treatment method described later, the bound and immobilized carrier used in the present embodiment supplies a new carrier in which microorganisms are not attached to the surface in the second aeration tank 4, and the second aeration tank 4 is produced by supplying 1,4-dioxane-containing organic waste water 1 to be treated into 4 and gradually attaching and fixing 1,4-dioxane-degrading bacteria on the surface of the new carrier. Therefore, for example, as described in Patent Documents 3 and 4, the microorganisms are preliminarily encapsulated with a resin or the like, and are produced by a mechanism separate from the biological treatment apparatus by an entrapment immobilization method in which the microorganisms are taken in and fixed inside the resin. Compared to the case of using the entrapping immobilization support, the time required for stabilization of the biological treatment apparatus can be shortened. Furthermore, according to the binding immobilization carrier according to the present embodiment, 1,4-dioxane degrading bacteria accustomed to the raw aqueous state adhere and fix at high density. Therefore, 1,4-dioxane can be stably decomposed and removed, and the activity of 1,4-dioxane-degrading bacteria is increased even when there is a change in the concentration of organic matter in the influent wastewater, compared to conventional entrapping immobilization carriers. While maintaining, 1,4-dioxane in wastewater can be stably decomposed in a shorter time.

  Since the second aeration tank 4 is a reaction tank mainly for decomposing and removing 1,4-dioxane, it is preferable that the biocarrier to be charged can stably adhere and fix 1,4-dioxane degrading bacteria. As the material of the carrier put into the second aeration tank 4, synthetic polymers such as polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyacrylamide, and photocurable resin, and polymers such as carrageenan and sodium alginate are used. Examples include gel carriers used, carriers made of polyethylene, polyurethane, polypropylene, etc., sponges made of polyester, polyolefin, rayon, cellulose, and nonwoven fabric carriers. It is also possible to use a carrier based on an inorganic substance such as activated carbon or anthracite.

  As the shape of the carrier charged into the second aeration tank 4, any of a spherical shape, a square shape, and a cylindrical shape can be used, and its effective diameter is stabilized by a screen provided at the outlet of the second aeration tank 4. 2 to 20 mm, more preferably 3 to 15 mm, and still more preferably 3 to 10 mm. The specific gravity of the carrier is 1.01 to 1.15, more preferably 1.01 to 1.10, and more preferably 1.01 to 1.03 which is close to the specific gravity of the aeration tank mixed sludge. Are preferred. The carrier filling amount is preferably from 5 to 30 V%, more preferably from 10 to 20 V%, which enables uniform flow of mixing.

  Among these, a sponge carrier made of polyethylene, polyurethane, polypropylene or the like having a network structure on the surface or the whole is preferable. In addition, a gel carrier using a synthetic polymer such as polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyacrylamide, or photocurable resin, or a polymer such as carrageenan or sodium alginate may be fine on the surface of the carrier or on the whole. Those having a fine pore or network structure are preferred.

  In the case of a sponge carrier, the effective diameter is preferably 5 to 20 mm, and the volume filling rate with respect to the aeration tank is preferably 10 to 30% so that the flow in the tank is uniform. A sponge carrier having a network structure with internal pores of 50 to 5000 μm is used. Preferably, the thing of 100-1000 micrometers is used. In the case of a gel carrier other than the sponge carrier, the effective diameter is preferably 3 to 10 mm, and the volume filling rate with respect to the aeration tank is preferably 5 to 20% so that the flow in the tank is uniform. A carrier having fine pores on the surface is used. A pore diameter of 5 to 500 μm is used. Preferably, the thing of 5-100 micrometers is used.

  In the 2nd aeration tank 4, it is desirable to make microbial carrier and activated sludge coexist. Even if the quality of the raw water flowing into the second aeration tank 4 fluctuates due to the coexistence of the activated sludge, it can be averaged by the activated sludge treatment. Therefore, 1,4-dioxane-decomposing bacteria adhere to the carrier and there is almost no influence on the decomposition treatment by 1,4-dioxane-degrading bacteria, and stable biological treatment can be performed.

  The BOD of the first treatment liquid 3 supplied to the second aeration tank 4 is greatly reduced by the treatment in the first aeration tank 2. When the first treatment liquid 3 is introduced into the second aeration tank 4 where the microorganism carrier and the activated sludge coexist, the BOD slightly remaining in the first aeration tank 2 is decomposed by the activated sludge in the second aeration tank 4. While being removed, 1,4-dioxane in the first treatment liquid 3 is decomposed and removed by 1,4-dioxane degrading bacteria attached to the carrier.

  In the second aeration tank 4, the organic component to be decomposed is almost 1,4-dioxane. Therefore, 1,4-dioxane-degrading bacteria are gradually put on the surface of the carrier filled in the second aeration tank 4. Adhesion can be fixed. At this time, by coexisting activated sludge, 1,4-dioxane-degrading bacteria adhere stably to the surface of the carrier due to the action of extracellular polymers and extracellular enzymes produced from BOD oxidizing bacteria in the activated sludge. To do.

  For example, when the 1st process liquid 3 is supplied in the 2nd aeration tank 4 at 100-300 L / d and the decomposition process of 1, 4- dioxane is performed, the BOD sludge load of the 2nd aeration tank 4 is 0.1 kg / kg. / D or less, more preferably 0.03 to 0.07 kg / kg / d, still more preferably 0.03 to 0.05 kg / kg / d, and activated sludge suspended solids concentration (MLSS) 1000 to 8000 mg / L, Preferably it can be processed at 4000-5500 mg / L.

  Immediately after adding an unused new carrier in the second aeration tank 4, 1,4-dioxane-degrading bacteria are grown in the second aeration tank 4 and 1,4-dioxane on the surface of the new carrier. In order to promote the attachment of degrading bacteria, it is preferable to adjust the BOD sludge load of the second aeration tank 4 to 0.05 kg / kg / d or less.

  In the solid-liquid separation device (sedimentation basin) 6, for example, the treated water 7 and the concentrated sludge 8 are obtained by settling and separating the activated sludge contained in the second treatment liquid 5. The concentrated sludge 8 obtained by the solid-liquid separator 6 is supplied into the first aeration tank 2 via the return line 11. By supplying the concentrated sludge 8 to the first aeration tank 2, an effect of stably maintaining the MLSS of the first aeration tank 2 is obtained. The excess sludge 9 generated in the solid-liquid separator 6 can be discharged out of the system and supplied to the sludge treatment facility.

(Biological treatment method)
Next, the biological treatment method according to the embodiment of the present invention will be described. The biological treatment method according to the present embodiment includes a first treatment step in which 1,4-dioxane-containing organic wastewater 1 is treated in a first aeration tank 2 containing activated sludge to obtain a first treatment liquid 3; 1 treatment liquid 3 is introduced into a second aeration tank 4 containing a microorganism carrier carrying microorganisms that decompose 1,4-dioxane and activated sludge, and the first treatment liquid 3 is added by the microorganism carrier in the presence of activated sludge. A second treatment step for decomposing 1,4-dioxane therein to obtain a second treatment liquid 5, and a solid-liquid separation step for obtaining a treated water 7 and concentrated sludge 8 by solid-liquid separation of the second treatment liquid 5; And a returning step of returning the concentrated sludge 8 into the first aeration tank 2.

  In particular, in the present embodiment, a new carrier in which microorganisms are not immobilized is supplied into the second aeration tank 4, the microorganisms are attached to the surface of the new carrier, and the microorganisms that decompose 1,4-dioxane are used as carriers. It is preferable to include a microorganism attaching step for producing a binding immobilization carrier adhered and fixed on the surface of the substrate.

  The microorganism attaching step can be performed during a so-called start-up, that is, a preliminary step for stabilizing the biological treatment apparatus before the actual load operation of the 1,4-dioxane-containing organic wastewater 1 is started. Therefore, as compared with the conventional case where a entrapping immobilization support in which 1,4-dioxane-degrading bacteria are cultured and immobilized in advance is used as in the prior art, the culturing including the cell culture until reaching the actual load operation is performed. The raising time can be shortened. Furthermore, by producing a microbial carrier using 1,4-dioxane-containing organic wastewater 1 to be actually treated, 1,4-dioxane bacteria having higher activity can be stably held on the carrier. .

  In the microorganism attaching step, the first treatment liquid 3 obtained in the first aeration tank 2 is supplied into the second aeration tank 4 containing the unused new carrier to which activated sludge and microorganisms are not attached. Treatment liquid 3 is treated with a BOD sludge load of 0.05 kg / kg / d or less. As a result, microorganisms that decompose 1,4-dioxane are grown in the second aeration tank 4. Proliferated 1,4-dioxane degrading microorganisms gradually adhere on the surface of the new carrier. From the viewpoint of the microorganism adhesion effect, the microorganism adhesion step is preferably performed at a water temperature of 20 ° C. or higher in the second aeration tank 4, pH 5.8 to 8.7, and a dissolved oxygen concentration of 2 mg / L or higher. Although the period required for microorganisms attachment changes with conditions, it is about 7 to 14 days from the start of water flow.

  As general processing conditions for the first aeration tank 2 and the second aeration tank 4 after the desired microorganism carrier is obtained in the second aeration tank 4, the water temperature is preferably 15 to 35 ° C. Since the pH of the first aeration tank 2 and the second aeration tank 4 varies depending on the inflow raw water state, it is preferably 5.8 to 8.7, and preferably 6.0 to 8.0. In particular, in the second aeration tank 4, it is preferable to maintain the pH at 6.5 to 8.0 so that 1,4-dioxane-degrading bacteria can easily adhere to the carrier.

  The dissolved oxygen concentration (DO) of the first aeration tank 2 and the second aeration tank 4 may be 1 mg / L or more in the first aeration tank 2. On the other hand, in the 2nd aeration tank 4 which added the support | carrier, DO is 2 mg / L or more, Preferably, it is preferable to set it as 2.5-4.0 mg / L. In particular, when the 1,4-dioxane inflow load is high, if the second aeration tank DO is increased by 3 mg / L or more, the activity of the 1,4-dioxane-decomposing bacteria-adhering carrier is high, and good decomposition efficiency is obtained.

(First modification)
As shown in FIG. 2, the biological treatment apparatus and biological treatment method according to the first modification dispense a part of the 1,4-dioxane-containing organic waste water 1 before supplying it into the first aeration tank 2. The biological treatment apparatus and biological treatment method shown in FIG. 1 further includes a dispensing step of supplying a part of the 1,4-dioxane-containing organic waste water 1 to the second aeration tank 4 via the dispensing line 21. Different.

  The dispensing line 21 is connected to a dispenser 20 that is connected to a pipe on the upstream side of the first aeration tank 2. In the dispenser 20, the 1,4-dioxane-containing organic waste water 1 is dispensed at a predetermined ratio. The ratio of the 1,4-dioxane-containing organic waste water 1 supplied to the second aeration tank 4 is 5 to 50% of the total water amount, more preferably 10 to 30%, and still more preferably 15 to 20%. Extracellular polymer produced from BOD oxidizing bacteria contained in activated sludge in the second aeration tank 4 by directly supplying a part of the 1,4-dioxane-containing organic waste water 1 into the second aeration tank 4 And the function of the extracellular enzyme becomes active. As a result, adhesion of 1,4-dioxane degrading bacteria to the surface of the carrier is promoted, and 1,4-dioxane can be stably decomposed and removed.

(Second modification)
As shown in FIG. 3, the biological treatment apparatus and biological treatment method according to the second modification dispense a part of the concentrated sludge 8 before returning it to the first aeration tank 2, and then in the second aeration tank 4. 2 differs from the biological treatment apparatus and biological treatment method shown in FIG. 2 in that it further includes a dispensing and returning step of returning a part of the concentrated sludge 8 into the second aeration tank 4 via the dispensing and returning line 31 that is returned to .

  The dispensing return line 31 is connected to a dispenser 30 provided in the middle of the piping of the return line 11. In the dispenser 30, the concentrated sludge 8 is dispensed at a predetermined ratio. The ratio of the concentrated sludge 8 supplied to the second aeration tank 4 is 5 to 50%, more preferably 10 to 30%, still more preferably 15 to 20% of the total concentrated sludge amount to be returned. By directly supplying a part of the concentrated sludge 8 into the second aeration tank 4, the BOD sludge load in the second aeration tank 4 can be reduced to a predetermined value or less. Adhesion of dioxane-degrading bacteria is promoted, and 1,4-dioxane can be decomposed and removed stably.

(Other embodiments)
Although the present invention has been described according to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments and operational techniques will be apparent to those skilled in the art.

  In this embodiment, although the example which processes the 1, 4- dioxane containing organic waste water 1 using two aeration tanks (the 1st aeration tank 2 and the 2nd aeration tank 4) is made into a process target. It goes without saying that various devices may be added according to the characteristics of the 1,4-dioxane-containing organic wastewater 1.

  For example, you may provide the sludge settling tank for isolate | separating a 1st process liquid into sludge and a supernatant liquid in the back | latter stage of the 1st aeration tank 2. FIG. For the first aeration tank 2 and the second aeration tank 4, one or more devices selected from the group consisting of a coagulation sedimentation processing device, an activated carbon adsorption device, a sand filtration processing device, and an MF processing device may be combined. Since both the first aeration tank 2 and the second aeration tank 4 are processed under aerobic conditions, it is possible to provide a partition in one reaction tank and arrange both in the one reaction tank. is there.

  In the present embodiment, an example in which a bound and immobilized carrier is used as a microorganism carrier is shown. However, in order to increase the growth rate of 1,4-dioxane-decomposing bacteria, inoculum of 1,4-dioxane-decomposing bacteria may be introduced into the second aeration tank 4. In order to increase the density of 1,4-dioxane degrading bacteria, a known entrapping immobilization carrier can be further added. A carrier for 1,4-dioxane degrading bacteria may be supplied to the first aeration tank 2.

  When 1,4-dioxane cannot be decomposed and removed even by the biological treatment apparatus shown in FIGS. 1 to 3, the treated water 7 is further introduced into the AOP decomposition treatment apparatus, and the 1,4-dioxane concentration in the treated water 7 May be decomposed. Thus, it goes without saying that the present invention includes various embodiments and the like not described herein, and the technical scope of the present invention is determined by the invention specific matters according to the appropriate claims from the above description. It is done.

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

Example 1
1,4-Dioxane containing organic waste water (raw water) was processed using the biological treatment apparatus shown in FIG. Table 1 shows the processing conditions of Example 1. As shown in Table 1, the total amount of raw water 200 L / d was continuously supplied to the first aeration tank, and the BOD sludge load was 0.3 kg / kg / d. Moreover, the BOD sludge load of the second aeration tank was set to 0.04 kg / kg / d. Activated sludge was supplied to the first aeration tank, and its MLSS was adjusted to 4500 to 5000 mg / L. To the second aeration tank, 20 V% of a polymer gel carrier (hereinafter referred to as PVA carrier) mainly composed of polyvinyl alcohol having an average particle diameter of 4 mm and a specific gravity of 1.025 is added, and the first treatment liquid obtained in the first aeration tank is second While treating in an aeration tank, 1,4-dioxane-degrading bacteria were attached to the surface of the PVA carrier. The MLSS concentration in the second aeration tank was 4500 to 5000 mg / L as in the first aeration tank. The sludge return rate from the sedimentation basin to the first aeration tank was 100%. The “sludge return rate” in Table 1 indicates the ratio of the returned amount of concentrated sludge to the amount of raw water flowing into the first aeration tank. That is, in Example 1, since the sludge return amount was set to 200 L / d similarly to the raw water amount, the sludge return rate in Table 1 was 100%.

  Table 2 shows the quality of raw water and its treatment results. The “first aeration tank” in Table 2 shows the results when the water quality of the supernatant liquid obtained by sedimentation and separation of the first treatment liquid 3 obtained in the first aeration tank 2 of FIG. 1 is evaluated. The “treated water” in Table 2 indicates the quality of the treated water 7 after solid-liquid separation in the sedimentation basin 6 of FIG.

  As shown in Table 2, the BOD was 850 mg / L for raw water, whereas the first aeration tank treatment liquid was reduced to 60 mg / L. Furthermore, in the treated water which passed through the 2nd aeration tank, it became 10 mg / L or less. COD and TOC were 450 mg / L and 420 mg / L for raw water, respectively, whereas COD and TOC of the first aeration tank treatment liquid were 68 mg / L and 98 mg / L, and most of the organic matter was in the first aeration tank. Was removed by decomposition. On the other hand, 1,4-dioxane is 88 mg / L in the first aeration tank treatment liquid with respect to 103 mg / L in the raw water, and most remains. On the other hand, in the treated water which passed through the 2nd aeration tank, 1, 4- dioxane fell to 0.5 mg / L and the removal effect by the 1, 4- dioxane decomposing bacteria of PVA carrier adhesion has been confirmed. Further, the treated water COD decreased to 28 mg / L and the TOC decreased to 18 mg / L, and COD and TOC could be decomposed and removed together with residual BOD removal.

(Example 2)
1,4-Dioxane-containing organic waste water (raw water) was treated according to the treatment flow shown in FIG. Raw water is the same as in Example 1. Table 3 shows the processing conditions of Example 2. In Example 2, 170 L / d, which is 85% of the total water amount, was continuously passed through the first aeration tank 2 out of the total raw water amount of 200 L / d. The remaining 15%, 30 L / d, was continuously passed directly into the second aeration tank as dispensed water. Thereby, the BOD sludge load of the 1st aeration tank and the 2nd aeration tank became 0.21 kg / kg / d and 0.06 kg / kg / d, respectively. In the same manner as in Example 1, 20 V% of the PVA carrier for fixing 1,4-dioxane-degrading bacteria was fixed to the second aeration tank. The concentrated sludge obtained in the sedimentation basin was returned to the first aeration tank at a return ratio of 100%. MLSS of the 1st aeration tank and the 2nd aeration tank was 5000-5500 mg / L and 4500-5000 mg / L, respectively.

  Table 4 shows the quality of raw water and its treatment results. In Example 2, the raw water BOD was 850 mg / L, whereas in the first aeration tank, the treated water BOD was reduced to 15 mg / L. However, 1,4-dioxane remained at 88 mg / L. In contrast, in the second aeration tank, the treated water BOD and 1,4-dioxane were reduced to 10 mg / L or less and 0.3 mg / L, respectively. In the second aeration tank, it was confirmed that the BOD of the raw water for dispensing was decomposed and removed by activated sludge, and decomposed and removed by 1,4-dioxane-degrading bacteria adhered and fixed to the PVA carrier charged with 1,4-dioxane. It was.

(Example 3)
1,4-Dioxane containing organic waste water (raw water) was processed using the biological treatment apparatus shown in FIG. Table 5 shows the processing conditions of Example 3. The dispensing ratio of the raw water into the first aeration tank and the second aeration tank is the same as that in Example 2. In Example 3, regarding the return of the concentrated sludge obtained by the solid-liquid separator to the second aeration tank, the second aeration tank was dispensed. As shown in Table 5, since the sludge return rates of the first aeration tank and the second aeration tank were both 100%, the return sludge amounts were 170 L / d and 30 L / d, respectively. That is, the ratio of the supplied concentrated sludge was 85% in the first aeration tank and 15% in the second aeration tank with respect to the total concentrated sludge. As a result, the BOD load was 0.23 kg / kg / d in the first aeration tank and 0.04 kg / kg / d in the second aeration tank, and the BOD load in the second aeration tank was further reduced from Example 2.

  Table 6 shows the quality of raw water and its treatment results. In Example 3, the raw water BOD was 850 mg / L, whereas in the first aeration tank, the treated water BOD was reduced to 21 mg / L. However, 1,4-dioxane remained at 89 mg / L. On the other hand, in the second aeration tank, the concentrations of treated water BOD and 1,4-dioxane decreased to 10 mg / L or less and 0.2 mg / L, respectively. In particular, the 1,4-dioxane concentration in the treated water was further reduced from that in Example 2.

(Comparative example)
1,4-dioxane containing organic waste water (raw water) was processed using a biological treatment apparatus provided with the aeration tank 200 and the solid-liquid separation apparatus 600 shown in FIG. In the comparative example, treated water 7 was obtained using the same raw water as in Example 1. Table 7 shows the processing conditions.

  The amount of treated water in the comparative example was 200 L / d as in Example 1. The MLSS was 4500 to 5000 mg / L, which was the same as that of Example 1. The BOD load of the aeration tank was 0.15 to 0.20 kg / kg / d, which was almost the same as the BOD load of Example 1.

  Table 8 shows the quality of raw water and its treatment results. In the comparative example, the raw water BOD was 850 mg / L, the treated water BOD was 10 mg / L or less, and the BOD removal was good. On the other hand, 1,4-dioxane was 103 mg / L in the raw water, and 85 mg / L in the treated water. Most of the residue remained, and the removal effect of 1,4-dioxane was hardly recognized.

1 ... Organic wastewater containing 1,4-dioxane (raw water)
2 ... 1st aeration tank 3 ... 1st process liquid 4 ... 2nd aeration tank 5 ... 2nd process liquid 6 ... Solid-liquid separation apparatus (sedimentation basin)
7 ... Second treated water 8 ... Concentrated sludge 9 ... Excess sludge 11 ... Return line 20 ... Dispenser 21 ... Dispenser line 30 ... Dispenser 31 ... Dispenser return line

Claims (7)

A first treatment step of treating 1,4-dioxane-containing organic wastewater in a first aeration tank containing activated sludge to obtain a first treatment liquid;
The first treatment liquid is introduced into a second aeration tank containing a microorganism carrier supporting microorganisms that decompose 1,4-dioxane and activated sludge, and the first microorganism is supported by the microorganism carrier in the presence of the activated sludge. A second treatment step of decomposing 1,4-dioxane in the treatment liquid to obtain a second treatment liquid;
A solid-liquid separation step for solid-liquid separation of the second treatment liquid to obtain treated water and concentrated sludge;
A biological treatment method of 1,4-dioxane-containing organic wastewater, comprising a returning step of returning the concentrated sludge into the first aeration tank.   The 1,4-dioxane-containing organic waste water is dispensed before being supplied into the first aeration tank, and includes a dispensing step of supplying the second aeration tank to the first aeration tank. Biological treatment method of 4-dioxane containing organic wastewater.   The 1,4-dioxane according to claim 1 or 2, comprising a dispensing and returning step of dispensing a part of the concentrated sludge before returning it to the first aeration tank and returning it to the second aeration tank. Biological treatment method for organic wastewater.   The 1,4-dioxane-containing organic material according to any one of claims 1 to 3, wherein the microbial carrier includes a bonded immobilized carrier in which a microorganism that decomposes 1,4-dioxane is adhered and fixed on the surface of the carrier. Of biological wastewater.   The first treatment step includes a treatment with a BOD sludge load of the first aeration tank of 0.1 to 0.5 kg / kg / d, and the second treatment step includes a BOD sludge of the second aeration tank. The biological treatment method for 1,4-dioxane-containing organic wastewater according to any one of claims 1 to 4, comprising treatment at a load of 0.1 kg / kg / d or less.   A new carrier is supplied into the second aeration tank, and the first treatment liquid is treated with a BOD sludge load of 0.05 kg / kg / d or less to remove microorganisms that decompose 1,4-dioxane into the second aeration tank. The biological treatment of 1,4-dioxane-containing organic wastewater according to any one of claims 1 to 5, further comprising a microorganism adhesion step for growing the microorganisms in a cell and depositing the grown microorganisms on the surface of the new carrier. Method. A first aeration tank for decomposing organic matter in 1,4-dioxane-containing organic wastewater with activated sludge to obtain a first treatment liquid;
A second aeration tank that obtains a second treatment liquid by decomposing 1,4-dioxane in the first treatment liquid by a microorganism carrier carrying a microorganism that decomposes 1,4-dioxane in the presence of activated sludge;
A solid-liquid separation device for solid-liquid separation of the second treatment liquid to obtain treated water and concentrated sludge;
A biological treatment apparatus for 1,4-dioxane-containing organic wastewater, comprising a concentrated sludge return line for returning the concentrated sludge from the solid-liquid separator to the first aeration tank.

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