JP7084205B2 - Wastewater treatment equipment using gas permeable membrane - Google Patents

Description

The present invention relates to a wastewater treatment apparatus using microorganisms. More specifically, the present invention relates to a wastewater treatment apparatus that uses a gas permeable membrane and has both wastewater treatment efficiency and energy saving.

In Japan, as a wastewater treatment method, an activated sludge method that decomposes sludge substances (organic substances, nitrogen compounds, etc.) by utilizing the action of aerobic microorganisms is widely used. Non-Patent Document 1 describes the amount of BOD (biochemical oxygen demand) in daily sewage applied per BOD-SS load (unit MLSS amount [kg]] in sewage treatment by the standard active sludge method [kg / day]. ) Is 0.2 to 0.4 kgBOD / kgSS · day, and the MLSS (Mixed liquor Suspended Solid) concentration is 1,500 to 2,000 mg / L. This corresponds to a BOD volumetric load of 0.3-0.8 kg BOD / m ³ / day. According to the fact that the general activated sludge removal rate is 90%, it can be said that the BOD removal rate is 0.27 to 0.72 kg BOD / m ³ / day in the standard activated sludge method. The BOD removal rate is a numerical value corresponding to "the amount of sludge substance decomposed by the effective unit volume of the wastewater treatment tank per day".

Further, as an example of the wastewater treatment method by the activated sludge method, there is a method of directly supplying oxygen necessary for decomposing sludge substances to wastewater by using an aeration device. Examples of a general aeration device include a composite device that combines a blower and an air diffuser, and a mechanical aeration device. Examples of the aeration device that can be used in the aeration device include those having a porous resin air diffuser and a rubber membrane diffuser.

Further, Patent Documents 1 to 3 disclose a wastewater treatment device using a gas permeable membrane as a device that does not require an aeration device.

Japanese Patent No. 4680504 Japanese Patent No. 3743771 JP-A-2015-33681

Sewerage facility planning / design guidelines and explanations Part 2-2009 edition-P80

By the way, in the activated sludge method using an aeration device, it is necessary to directly send air into the wastewater against the water pressure, so that the energy consumption is large.

Further, in Patent Documents 1 to 3 using a gas permeable membrane, the oxygen supply performance, the required membrane area, and the water resistance performance of the gas permeable membrane, which are important for wastewater treatment, are not examined. Therefore, when Patent Documents 1 to 3 are applied to an actual wastewater treatment apparatus, it is unclear how much the volume of the wastewater treatment tank will be, how deep the water can be applied, or how to design the wastewater treatment layer. Is. Further, Patent Document 3 describes an example of sending air to a gas permeable membrane, but in this example, a large amount of energy is required.

The present invention has been made to solve the above problems, and an object thereof is that it does not require the use of an aeration device or an increase in the volume of a wastewater treatment tank, and the treatment performance is defined as a standard activated sludge method. It is to provide a wastewater treatment device that can be equivalent.

In order to achieve the above object, the present invention includes the subjects described in the following sections.

Item 1. A wastewater treatment device that activates microorganisms in wastewater by supplying oxygen that has permeated through a gas permeable membrane to the wastewater stored inside the wastewater treatment tank, and purifies the wastewater by the activity of the microorganisms.
BOD removal performance by the gas permeable film per unit area AgBOD / m ² / day multiplied by the installation area B m ² / m ³ of the gas permeable film per effective unit volume of the wastewater treatment tank A × A wastewater treatment device characterized in that B g BOD / m ³ / day is 0.5 kg BOD / m ³ / day or more.

Item 2. The amount of oxygen permeated per day in the unit area of the gas permeable membrane is 25 g / m ² or more under atmospheric pressure.
Item 2. The wastewater treatment apparatus according to Item 1, wherein the installation area B m ² / m ³ of the gas permeable membrane per effective unit volume of the waste water treatment tank is 25 m ² / m ³ or more.

Item 3. A gas feeder provided with the gas permeable membrane and the gas delivery layer is arranged inside the wastewater treatment tank.
Item 2. The wastewater treatment apparatus according to Item 1 or 2, wherein oxygen delivered from the gas delivery layer to the gas permeable membrane permeates the gas permeable membrane and is supplied to the wastewater.

Item 4. Item 3. The item 3 is characterized in that a plurality of the gas feeders are arranged side by side in the wastewater treatment tank, and the distance between two adjacent gas feeders is 15 mm or more and 50 mm or less. Wastewater treatment equipment.

Item 5. It has a feeder unit that holds a plurality of the gas feeders in parallel, and has a feeder unit.
Item 3. The wastewater treatment apparatus according to Item 3 or 4, wherein one or more of the feeder units are installed inside the wastewater treatment tank.

Item 6. Item 5. The wastewater treatment apparatus according to Item 5, wherein the installation area B m ² / m ³ of the gas permeable membrane per unit volume of the waste water treatment tank is 28 m ² / m ³ or more.

Item 7. Item 5. The wastewater treatment apparatus according to Item 5 or 6, wherein the gas permeable membrane included in the feeder unit is installed in the wastewater treatment tank so as to be substantially parallel to the flow direction of the wastewater. ..

Item 8. Item 1 is characterized in that a diving weir is installed in the vicinity of the inflow port inside the wastewater treatment tank, and an overflow weir is installed in the vicinity of the outflow port inside the wastewater treatment tank. The wastewater treatment apparatus according to any one of 7 to 7.

Item 9. Item 2. The wastewater treatment apparatus according to any one of Items 1 to 8, wherein an overflow weir and a submersible weir are installed in the middle portion of the wastewater treatment tank.

Item 10. Item 2. The wastewater treatment apparatus according to any one of Items 1 to 9, wherein the gas permeable membrane has a short-term pressure resistance of 0.2 Mpa or more.

In the wastewater treatment apparatus of the present invention, the BOD removal performance of the gas permeable film 21 is AgBOD / m ² / day and the installation area of the gas permeable film 21 so that the BOD removal rate is 0.5 kgBOD / m ³ / day or more. B m ² / m ³ is adjusted, and the above 0.5 kg BOD / m ³ / day corresponds to the intermediate value of the BOD removal rate of the standard activated sludge method. Therefore, according to the wastewater treatment apparatus of the present invention, it is not necessary to use an aeration apparatus or increase the volume of the wastewater treatment tank, and the treatment performance can be made equivalent to that of the standard activated sludge method.

It is a vertical sectional view of the wastewater treatment apparatus which concerns on embodiment of this invention. It is a horizontal sectional view of the wastewater treatment apparatus which concerns on embodiment of this invention. It is a vertical cross-sectional view of the wastewater treatment apparatus which concerns on embodiment of this invention, and shows the cross section orthogonal to FIG. It is a vertical sectional view of a gas feeder arranged in a wastewater treatment apparatus. It is a perspective view which shows the gas delivery layer which constitutes the gas supply body of FIG. It is a flowchart which shows the flow of the manufacturing method of the gas feeder of FIG. The method of forming a bag from a gas permeable membrane is shown, (a) is a perspective view, and (b) is a sectional view. It is a schematic diagram which shows the process of inserting a gas delivery layer into the bag formed from a gas permeation membrane. Description of the microbial aggregate formed on the surface of the gas permeable membrane of the gas feeder immersed in the wastewater in the wastewater treatment tank of the wastewater treatment apparatus of FIG. 1, and the decomposition of at least one organic substance or nitrogen source by the microorganisms. It is a schematic diagram. It is a perspective view which shows the feeder unit which holds a plurality of gas feeders in parallel. It is a side view which shows the feeder unit which holds a plurality of gas feeders in parallel. It is a vertical sectional view of the wastewater treatment apparatus provided with a feeder unit. It is a top view of the wastewater treatment apparatus provided with a feeder unit. It is a vertical cross-sectional view of the wastewater treatment apparatus provided with a feeder unit, and shows the cross section orthogonal to FIG. FIG. 3 is a plan view showing another example of a wastewater treatment device including a feeder unit.

Hereinafter, the wastewater treatment apparatus according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of the wastewater treatment apparatus 50 according to the embodiment of the present invention. FIG. 2 is a horizontal cross-sectional view of the wastewater treatment device 50. FIG. 3 is a vertical cross-sectional view of the wastewater treatment apparatus 50, showing a cross section orthogonal to FIG.

(Wastewater treatment device 50)
As shown in FIGS. 1 to 3, the wastewater treatment apparatus 50 of the present embodiment includes a wastewater treatment tank 51 and a gas supply body 10. The gas supply body 10 is provided with a gas permeation membrane 21, and oxygen permeated through the gas permeation membrane 21 is supplied to the wastewater W stored inside the wastewater treatment tank 51. As a result, aerobic microorganisms in the wastewater W are activated, and sludge substances (organic substances, nitrogen compounds, etc.) are decomposed by the activity of the microorganisms, so that the wastewater is purified. Hereinafter, the configuration of the wastewater treatment device 50 will be specifically described.

(Wastewater treatment tank 51)
As shown in FIGS. 1 to 3, the wastewater treatment tank 51 is a bottomed container capable of storing the wastewater W, and has an inflow port 51a through which the wastewater W flows in and an outflow port 51b through which the wastewater W flows out. Have.

In the present embodiment, the inflow port 51a and the outflow port 51b are always open. The waste water W is continuously or intermittently supplied from the inflow port 51a toward the outflow port 51b arranged at a position facing the inflow port 51a (arrows in FIG. 3 indicate the flow of the waste water W). Is shown).

The volume of the wastewater treatment tank 51 is not particularly limited, but may be, for example, 1 m ³ or more and 10,000 m ³ or less.

(Gas feeder 10)
As shown in FIG. 1, when the wastewater treatment apparatus 50 is used, a plurality of gas feeders 10 are arranged side by side inside the wastewater treatment tank 51. Each gas supply body 10 is a structure that supplies the gas supplied from the opening 21b into the wastewater W in a state where the portion excluding the upper end portion is immersed in the wastewater W of the wastewater treatment tank 51. The gas supplied into the waste water W via the gas feeder 10 is a gas containing oxygen (for example, air). In the present embodiment, by taking in the air near the opening 21b into the opening 21b, the air is supplied into the waste water W without using an aeration device. As a result, the aerobic microorganisms in the wastewater W are activated, and the sludge substance dissolved or dispersed in the water is decomposed by the activity of the microorganisms, and the wastewater is purified.

Each gas feeder 10 is a hollow flat plate-shaped member. Each gas feeder 10 is arranged so that the surface is developed along the vertical direction (depth direction) and the lateral direction (horizontal direction) in order to efficiently secure the contact area with the waste water W. ..

FIG. 4 is a vertical cross-sectional view of the gas feeder 10. The gas supply body 10 includes a gas delivery layer 12 and a gas transmission film 21, and the gas delivery layer 12 is arranged in a bag composed of the gas transmission film 21. The bag is formed by superimposing two gas permeable membranes 21 and 21 and adhering the three end portions of these gas permeable membranes 21 and 21 to the upper end portion (on the gas supply side in the gas delivery layer 12). It has an opening 21b at the end). By inserting the gas delivery layer 12 into the inside of the bag through the opening 21b, the outer periphery of the gas delivery layer 12 is covered with the gas transmission film 21. The position or shape of the opening 21b is not limited, and for example, a part of each end of the bag (including the top side, the bottom side, and the horizontal side (vertical line) of the bag) may be an opening.

It is preferable that each gas feeder 10 is arranged so that these side surfaces are substantially parallel to each other. When the wastewater treatment tank 51 is provided with the inflow port 51a and the outflow port 51b as in the wastewater treatment apparatus 50 of the present embodiment, the flow of the wastewater W is generated, and each gas supply body 10 is the wastewater W. It is more preferable that they are arranged in a direction that does not block the flow. In particular, when the inflow port 51a and the outflow port 51b are arranged to face each other as shown in FIGS. 2 and 3, the side surface of each gas supply body 10 with respect to the straight line connecting the inflow port 51a and the outflow port 51b. It is preferable that the gas feeders 10 are arranged so that they are parallel to each other. By doing so, the wastewater W supplied from the inflow port 51a into the wastewater treatment tank 51 smoothly flows toward the outflow port 51b.

When the distance between the gas supply bodies 10 is defined as the distance between the outer surfaces of two adjacent gas supply bodies 10 not including the thickness of the gas supply body 10, the lower limit of the distance between the gas supply bodies 10 is 5 mm or more. Is preferable. Further, the upper limit of the interval between the gas feeders 10 is preferably 200 mm or less. If the distance between the gas feeders 10 is less than 5 mm, there is a risk of clogging due to microorganisms growing on the gas permeable membrane 21. If the distance between the gas feeders 10 exceeds 200 mm, the contact with the wastewater may be poor. In order to surely avoid the above problem, the lower limit of the interval between the gas feeders 10 is more preferably 15 mm or more, and the upper limit of the interval between the gas feeders 10 is more preferably 50 mm or less.

(Gas delivery layer 12)
FIG. 5 is a perspective view showing the gas delivery layer 12. The gas delivery layer 12 is a hollow plate-shaped member, and is formed of any of paper, resin, and metal. The gas delivery layer 12 is a structure having a gas flow path S that sends out the gas supplied from the first end portion along the first direction (direction indicated by the two-point difference line in FIG. 5). The air in the vicinity of the opening 21b is supplied to the upper end portion of the gas delivery layer 12 through the opening 21b (FIG. 4). The gas delivery layer 12 has a gas flow path S that sends out the gas supplied to the upper end portion in the first direction, and discharges the gas from the gas passage hole 13 on the side surface.

More specifically, as shown in FIG. 5, the gas delivery layer 12 has a plurality of core materials 12a, a front liner 12b, and a back liner 12c. The front and back surfaces of the gas delivery layer 12 are composed of a front liner 12b and a back liner 12c, which are plate-shaped members.

Each of the plurality of core members 12a extends in the first direction, and is arranged at a predetermined interval in a direction orthogonal to the first direction. By sandwiching the plurality of core materials 12a between the front liner 12b and the back liner 12c, the space between the front liner 12b and the back liner 12c is partitioned by the core material 12a, and a plurality of gas flow paths are formed. S is formed.

Each core material 12a functions as a support portion that supports the space between the front liner 12b and the back liner 12c so as not to shrink when pressed from the front liner 12b and the back liner 12c side. As shown in FIGS. 1 to 3, when the gas feeder 10 is immersed in the waste water W, the core material 12a maintains a space between the front liner 12b and the back liner 12c, whereby the gas flow path is maintained. It is prevented that the cross-sectional area of S is reduced by water pressure. As a result, the amount of gas delivered in the gas delivery layer 12 (gas flow path S) is sufficiently secured.

A plurality of gas passage holes 13 are formed in the front liner 12b and the back liner 12c, respectively. The gas passage hole 13 is a through hole formed in the front liner 12b and the back liner 12c. The gas passage hole 13 communicates the gas flow path S with the gas permeation membrane 21, so that the gas flowing through the gas flow path S is supplied into the waste water W via the gas permeation membrane 21.

For example, the gas passage hole 13 is formed at the time of molding the gas delivery layer 12. Alternatively, the gas passage hole 13 may be formed by processing the front liner 12b and the back liner 12c after molding the gas delivery layer 12. Further, a porous sheet may be used as the front liner 12b and the back liner 12c. Further, if sufficient gas supply performance is obtained, a porous sheet may be used as the gas delivery layer 12.

As the material of each member constituting the gas delivery layer 12, paper, ceramic, aluminum, iron, plastic (polyolefin resin, polystyrene resin, polyester resin, polyvinyl chloride resin, acrylic resin, urethane resin, epoxy resin, polyamide resin, etc. Methyl cellulose resin, ethyl cellulose resin, polyvinyl alcohol resin, vinyl acetate resin, phenol resin, fluororesin, polyvinyl butyral resin) and the like can be mentioned.

The material of the gas delivery layer 12 is preferably paper, aluminum, iron, polyolefin resin, polystyrene resin, vinyl chloride resin, or polyester resin because of its excellent strength.

From the viewpoint of keeping the material cost low, it is preferable to use, for example, paper, polyolefin, polystyrene, vinyl chloride, a resin such as polyester, a metal such as aluminum, or the like as the material of the gas delivery layer 12. Further, by using the corrugated cardboard formed so that the gas flow path S extends in the first direction (see the two-point difference line in FIG. 5) as the gas delivery layer 12, the material cost of the gas delivery layer 12 can be suppressed at low cost. be able to.

The shape of the gas passage hole 13 of the gas delivery layer 12 can be various shapes such as a circular shape and a polygonal shape (including a honeycomb structure). The shape of the gas passage hole 13 is preferably a polygonal shape, and more preferably a rectangle or a square shape.

The length of the gas flow path S formed in the gas delivery layer 12 in the vertical direction (depth direction at the time of immersion) is preferably 0.2 m or more and 6 m or less. It is preferable that the length of the gas flow path S in the vertical direction is 0.2 m or more in that the gas flow path S can be easily maintained, the gas flow path S can be easily ventilated, and the wastewater treatment ability can be improved. From this point of view, the length of the gas flow path S in the vertical direction is more preferably 0.8 m or more, still more preferably 3.7 m or more. Further, it is preferable that the length of the gas flow path S in the vertical direction is 6 m or less from the viewpoint of better obtaining the effect of improving the wastewater treatment ability by ventilation of the gas flow path S and the ease of installation. Further, from this viewpoint, the length of the gas flow path S in the vertical direction is more preferably 4 m or less.

The length of the gas flow path S in the horizontal direction orthogonal to the vertical direction is preferably 0.2 m or more and 3.6 m or less. It is preferable that the lateral length of the gas flow path S is 0.2 m or more in that the contact area with the wastewater W is efficiently secured and the wastewater treatment efficiency is improved. It is preferable that the lateral length of the gas flow path S is 3.6 m or less in terms of ease of maintaining the strength of the entire gas supply body 10 and ease of installation of the gas supply body 10. From the above viewpoint, the lateral length of the gas flow path S is more preferably 0.4 m or more and 1.8 m or less.

The ratio of the water contact length Lw to the waste water W to the length Ls of the gas flow path S may be, for example, 80% or more and 95% or less (see FIG. 1 for the lengths Ls and Lw). It is preferable that the ratio of the water contact length Lw to the length Ls is equal to or more than the above lower limit value in that the amount of oxygen supplied from the gas flow path S is satisfactorily secured and the wastewater treatment efficiency is improved. It is preferable that the ratio of the water contact length Lw to the length Ls is not more than the upper limit value in terms of preventing the waste water W from entering the gas flow path S.

Alternatively, in order to prevent the waste water W from entering the gas flow path S, the water contact length Lw is set so that the water surface of the waste water W is separated from the opening 21b of the gas supply body 10 (gas permeable membrane 21) by 2 cm or more. You may.

(Gas permeable membrane 21)
The gas permeation membrane 21 is immersed in the liquid (in the waste water W) so that the outermost layer is in contact with the liquid (waste water W), and oxygen is transferred from the inside (gas delivery layer 12) to the outside (waste water W). It has the property of allowing waste water to permeate and not permeating from the outside (waste water W) to the inside (gas delivery layer 12).

As shown in FIG. 4, the gas permeable membrane 21 includes a base material 211, a gas permeable non-porous layer 212, and a microorganism support layer 213. In the illustrated example, the gas permeable membrane 21 is laminated in the order of the microorganism support layer 213, the base material 211, and the gas permeable non-porous layer 212, and the base material 211 is covered with the gas permeable non-porous layer 212 and is covered with the gas permeable non-porous layer 212. The outermost layer in contact with the waste water W is composed of the microbial support layer 213. The gas permeable membrane 21 may be one in which the base material 211, the gas permeable non-porous layer 212, and the microorganism support layer 213 are laminated in this order (conversely to the illustrated example, the base material 211 is gas permeable. It may be located inside the non-perforated layer 212). Even in this way, the base material 211 can be covered with the gas permeable non-porous layer 212, and the outermost layer in contact with the waste water W can be formed by the microorganism support layer 213.

(Base material 211)
The base material 211 is a microporous membrane formed of a thermoplastic resin (the microporous membrane is a membrane provided with a large number of fine through holes). Materials of the substrate 211 include polyolefins, polystyrene, polysulfones, polyethersulfones, polyarylsulfones, polymethylpentene, polytetrafluoroethylene, fluororesins including polyvinylidene fluoride, polybutadienes, and poly (dimethylsiloxanes). It may include silicone-based polymers, polymer materials selected from copolymers of these materials, and the like.

The method for producing the base material 211, which is a microporous membrane, is not particularly limited, but is based on any one of, for example, a phase separation method, a stretch opening method, a dissolution recrystallization method, a powder sintering method, a foaming method, and a solvent extraction. Material 211 can be manufactured. Further, the base material 211 may be a self-assembled honeycomb microporous film.

The thickness of the base material 211 is preferably 10 um or more and 500 um or less, and more preferably 50 um or more and 200 um or less. The thickness of the base material 211 is a value measured by the JIS 1913: 2010 general non-woven fabric test method 6.1 thickness measuring method.

The pore diameter of the base material 211 is preferably 0.01 um or more and 50 um or less from the viewpoint of preventing defects in the gas permeable membrane, and 0.1 um or more and 30 um or less from the viewpoint of maintaining high strength and gas permeability. Is more preferable. The pore diameter is a pore diameter obtained by observing the surface with a scanning electron microscope (SEM) and using the method shown below from the observation image. The observation magnification can be any magnification as long as the pore diameter of the object to be observed can be appropriately calculated.

<Method of determining pore diameter>
The image obtained by SEM observation is binarized, and the pore diameter is calculated by image analysis. At the time of calculation, the pore diameter is approximated to an ellipse, and the length of the major axis of the ellipse is used as the pore diameter, and the average value thereof is evaluated.

(Gas permeable non-porous layer 212)
The gas-permeable non-porous layer 212 is a layer having pores having a pore diameter smaller than the pores of the base material, or a layer in which the diameter of the pores cannot be detected and the gas can permeate. The pore diameter of the gas permeable non-porous layer 212 can be measured by the same method as the pore diameter of the base material 211.

The gas permeable non-porous layer 212 is a layer capable of permeating alcohols such as oxygen, carbon dioxide, nitrogen, hydrogen, methanol and ethanol, organic solvents, or a mixed gas thereof. The gas permeability of the layer 212 can be measured by the method specified in JIS K 7126.

The gas permeable non-porous layer 212 may be a thermoplastic resin or a thermosetting resin. The thermosetting resin may be a thermosetting resin or a resin that is cured by irradiation with ultraviolet rays. Further, it may be a resin that is cured by organic peroxide cross-linking, addition reaction cross-linking, or condensation cross-linking.

The material of the gas permeable non-porous layer 212 may include polyolefins, polystyrene, polysulfone, polyethersulfone polytetrafluoroethylene, acrylic resins, polyurethane resins and thermosetting polymers selected from copolymers of these materials. Further, a silicone-based silicon resin such as a polymer (dimethylsiloxane) having a siloxane skeleton of (Si—O—Si) n (n = integer) can be used. Among these, it is particularly preferable to use urethane resin and silicon resin.

Examples of the above polyurethane resin include "Asaflex 825" (manufactured by Asahi Kasei Corporation), "Pelesen 2363-80A", "Pelesen 2363-80AE", "Pelesen 2363-90A", "Pelesen 2363-90AE", (above, Dow). -Chemical) and "Heimlen Y-237NS" (manufactured by Dainichiseika Kogyo Co., Ltd.) can be used.

Examples of the above-mentioned silicone resin include "Shiraseal 3FW", "Shiraseal DC738RTV", "DC3145", and "DC3140" (all manufactured by Dow Corning), "ELASTOSIL RT707W", "ELASTOSIL EL4300", and "NC1910" (Asahi Kasei Wacker). Silicone), "SD4584PSA", "KS-847T", "KF-2005", "X-40-3237", "KNS-3002" (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used. A catalyst may be further added to the silicon resin. As the catalyst, an organic acid salt such as zinc octylate, iron octylate, cobalt or tin, or an amine-based catalyst can be used. Further, an organic tin compound, an organic titanium compound, and a platinum compound can also be used. As the catalyst, for example, "CAT-PL-50T" (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used. Further, at the time of coating, a solvent such as toluene or xylene may be added.

The method for manufacturing the gas permeable non-porous layer 212 is not particularly limited, and is a reverse roll coater, a forward rotation roll coater, a gravure coater, a knife coater, a rod coater, a slot orifice coater, an air doctor coater, a kiss coater, a blade coater, and a cast coater. , A gas permeable non-porous layer 212 can be manufactured by a method using a spray coater, a spin coater, an extrusion coater, a hot melt coater, or the like. Further, the gas permeable non-porous layer 212 can also be manufactured by a method such as powder coating or electrodeposition coating. The base material may be coated by immersing it in the raw material liquid of the gas permeable membrane. The base material may be in the form of a sheet or a hollow thread. In the pre-coating step, pre-treatment such as primer coating and corona treatment may be performed.

The basis weight of the gas-permeable non-porous layer 212 is preferably 10 g / m ² or more and 500 g / m ² or less, and more preferably 20 g / m ² or more and 200 g / m ² or less. The basis weight of the gas permeable non-porous layer 212 is the basis weight E (g / m ² ) of the base material before the gas permeable non-porous layer 212 is laminated and the gas permeation after the gas permeable film is laminated. It is obtained by the following relational expression (1) as D (g / m ² ), which is the difference between the non-porous layer 212 and the basis weight F (g / m ² ) of the base material.

[Equation 1]
D = FE (1)

The basis weight of the gas permeable non-porous layer 212 and the base material is the value measured by the mass per unit area of JIS 1913: 2010 General Nonwoven Fabric Test Method 6.2.

The thickness of the gas-permeable non-porous layer 212 is preferably 10 um or more and 500 um or less, and more preferably 20 um or more and 200 um or less. The thickness of the gas permeable non-porous layer 212 described above is a value measured by JIS 1913: 2010 General Nonwoven Fabric Test Method 6.1 Thickness Measuring Method.

(Microbial support layer 213)
The microorganism support layer 213 is a layer that holds microorganisms on its surface or inside, has a space in which microorganisms can grow, and allows organic substances in water to pass through. Examples of the material of the microorganism support layer 213 include a porous sheet such as a mesh, a woven fabric, a non-woven fabric, a foam, or a microporous membrane. The material of the porous sheet is polyolefin resin, polystyrene resin, polyester resin, polyvinyl chloride resin, acrylic resin, urethane resin, epoxy resin, polyamide resin, methyl cellulose resin, ethyl cellulose resin, polyvinyl alcohol resin, vinyl acetate resin, phenol resin, Examples thereof include fluororesins and polyvinyl butyral resins, polyimides, polyphenylene sulfides, para-based and meta-based aramids, polyarylates, carbon fibers, glass fibers, aluminum fibers, steel fibers, ceramics and the like. Considering microbial adhesion and processability, polyolefin resin, polyester resin, polyamide resin, acrylic resin, polyurethane resin, and carbon fiber are preferable.

The basis weight of the microorganism support layer 213 is preferably 2 g / m ² or more and 500 g / m ² or less, and more preferably 10 g / m ² or more and 200 g / m ² or less. The basis weight of the microbial support layer 213 is a value measured by the mass per unit area of JIS 1913: 2010 General Nonwoven Fabric Test Method 6.2.

The thickness of the microorganism support layer 213 is preferably 5 um or more and 2000 um or less, and more preferably 20 um or more and 500 um or less. The thickness of the microbial support layer 213 is a value measured by JIS 1913: 2010 General Nonwoven Fabric Test Method 6.1 Thickness Measuring Method.

The microorganism support layer 213 may be formed by the surface treatment of the base material 211. By doing so, the roughness and the membrane potential of the surface of the base material 211 can be increased by the above surface treatment, so that the microbial adhesion is improved. For example, as the above surface treatment, glycidyl methacrylate can be graft-polymerized and further reacted with diethylamine or sodium sulfite. Alternatively, as the above surface treatment, ammonia or ethylamine may be reacted after graft polymerization of glycidyl methacrylate.

<Manufacturing method of gas feeder 10>
The method for manufacturing the gas feeder 10 of the present embodiment is performed according to the flowchart shown in FIG. Hereinafter, a method for manufacturing the gas feeder 10 will be described with reference to FIG.

First, in step S11 of FIG. 6, a member such as a corrugated cardboard constituting the gas delivery layer 12 is arranged at a predetermined position.

Next, in step S12 of FIG. 6, a plurality of through holes as gas passage holes 13 are formed in the front liner 12b and the back liner 12c of the gas delivery layer 12 by using needle materials, respectively.

As the above-mentioned needle material, for example, a roll (needle material) to which a plurality of needles are attached to the surface, a needle material to which one needle is attached and a gas passage hole 13 can be manually formed, or the like can be used. can. By using these needle materials, even when the gas delivery layer is covered with a plate material or the like, the necessary gas passage holes can be easily formed. When the above roll is used, the gas passage hole 13 can be formed in the gas delivery layer 12 by passing the gas delivery layer 12 between the roll and the flat surface. The above plane is, for example, the surface of a flat plate or the surface of another roll to which a needle is not attached.

The gas passage hole 13 may be formed by pressing a plate on which needles are arranged on the surface against the surface of the gas delivery layer 12, or the gas passage hole 13 may be formed by using a cutting tool such as a cutter knife. May be good.

Next, in step S13 of FIG. 6, two substantially rectangular gas permeable membranes 21 and 21 are overlapped with each other, and the peripheral edges of the base materials 211 and 211 of the gas permeable membranes 21 and 21 are joined by heat fusion. , A bag made of gas permeable membranes 21 and 21 is formed (see FIG. 4 for the base material 211).

Specifically, as shown in FIG. 7, in a state where the gas permeable membranes 21 and 21 unwound from the two rolls R1 and R2 are overlapped, the three sides of the peripheral edges of the base materials 211 and 211 of the gas permeable membranes 21 and 21 are overlapped. The heat-welded portion 21c is formed by joining them together by heat-welding. Then, the gas permeable membranes 21 and 21 are cut at the portion to be the opening 21b in a state where three sides are sealed by the heat welding portion 21c (FIG. 7 shows a method of forming a bag from the gas permeable membranes 21 and 21). (A) is a perspective view, and (b) is a cross-sectional view).

The method of forming the bag from the gas permeable membrane 21 is not limited to the method shown in FIG. 7. For example, the bag may be formed by adhering only one opening of the gas permeable membrane 21 formed into a cylindrical shape. Alternatively, one gas permeable membrane 21 may be folded in half and the left and right ends are heat-welded to form a bag shape. Alternatively, a bag made of the gas permeable membrane 21 may be molded by inflation molding or the like. Alternatively, the hollow thread-shaped gas permeable membrane 21 can be obtained by continuous molding. For example, the base material may be continuously immersed in the raw material liquid of the gas permeable non-porous layer 212 and fixed by heat treatment, cooling, or the like as necessary to obtain the gas permeable film 21, or on a hollow base material. The raw material liquid of the gas permeable non-porous layer 212 may be continuously arranged in a mold using a mold and fixed by heat treatment, cooling or the like as necessary to obtain a gas permeable film 21. The temperature of the heat fusion is preferably equal to or higher than the melting point of the base material 211 formed of the thermoplastic resin and lower than the thermal decomposition temperature.

Further, the method of adhering the gas permeable film 21 is not limited to the above heat fusion, and the gas permeable film 21 may be adhered using, for example, a double-sided tape or an adhesive. The adhesive material preferably has at least one of water resistance, waterproofness, chemical resistance, and microbial decomposition resistance.

Next, in step S14 of FIG. 6, as shown in FIG. 8, the gas delivery layer 12 in which the gas passage hole 13 is formed is inserted into the bag interior 21d from the opening 21b of the bag made of the gas permeable membrane 21 (coating step). ).

The gas delivery layer 12 is inserted from the opening 21b along the direction of the gas flow path S formed by the core material 12a or the like.

In the wastewater treatment apparatus 50 of the present embodiment, the air (gas containing oxygen) supplied to the upper end portion 21b of the gas delivery layer 12 flows through the gas flow path S and passes through the gas passage hole 13. Then, the air passing through the gas passage hole 13 is supplied into the waste water W via the gas permeation membrane 21 (see FIG. 4). As a result, as shown in FIG. 9, aerobic microorganisms in the waste water W gather on the surface 21a of the gas permeation membrane 21 to which oxygen is continuously supplied. Therefore, microorganisms adhere to the surface 21a of the gas permeable membrane 21. Then, the sludge substance dissolved or dispersed in the water is decomposed by the action of the microorganism contained in the wastewater W or retained on the surface 21a, and the wastewater is purified. The sludge substance is a fine solid organic substance, a liquid organic substance such as acetic acid, or a nitrogen compound.

In the wastewater treatment apparatus 50 of the present embodiment, in order to make the purification treatment performance (BOD removal rate) equivalent to that of the standard activated sludge method, the BOD removal performance per unit area of the gas permeable film 21 is AgBOD / m ² / day. The BOD removal rate A × BgBOD / m ³ / day, which is the value obtained by multiplying the installation area Bm ² / m ³ of the gas permeable film 21 per effective unit volume of the wastewater treatment tank 51, is 0.5 kgBOD / m ³ /. It is considered to be day or more.

"BOD removal performance per unit area of gas permeation film 21 AgBOD / m ² / day" corresponds to "amount of sludge substance decomposed by oxygen permeating unit area of gas permeation film 21 per day". It is a numerical value.

The BOD removal rate "A x B gBOD / m ³ / day", which is obtained by multiplying "BOD removal performance AgBOD / m ² / day" and "installation area Bm ² / m ³ of the gas permeable film 21", is "gas permeable film". It is a numerical value corresponding to "amount of sludge substance per day decomposed by the effective unit volume of the wastewater treatment tank 51 by oxygen passing through the installation area of 21".

According to the fact that the BOD removal rate of the standard activated sludge method is 0.27 to 0.72 kgBOD / m ³ / day, the above BOD removal rate of 0.5 kgBOD / m ³ / day is the BOD of the standard activated sludge method. It corresponds to the intermediate value of the removal rate. In the wastewater treatment apparatus 50 of the present embodiment, the BOD removal performance of the gas permeable film 21 is AgBOD / m ² / day and the gas permeable film 21 is set so that the BOD removal rate is 0.5 kgBOD / m ³ / day or more. The installation area B m ² / m ³ is adjusted. Therefore, according to the wastewater treatment device 50 of the present embodiment, it is not necessary to use an aeration device or increase the volume of the wastewater treatment tank 51, and the treatment performance can be made equivalent to that of the standard activated sludge method.

In the present invention, the value of the BOD removal performance AgBOD / m ² / day and the value of the installation area Bm ² / m ³ of the gas permeable membrane 21 are determined based on the findings shown in the following (1) to (3). ..

(1) When the daily oxygen permeation amount in the unit area of the gas permeation membrane 21 is 25 gO ₂ / m ² / day or more under atmospheric pressure, the CODcr removal performance is 30 gCODcr / m ² / day or more. thing.
(2) When the daily oxygen permeation amount in the unit area of the gas permeation membrane 21 is 6 gO ₂ / m ² / day or more and less than 25 gO ₂ / m ² / day under atmospheric pressure, the CODcr removal performance is 8 gCODcr. Must be at least / m ² / day.
(3) The relationship between CODcr removal performance gCODcr / m ² / day and BOD removal performance gBOD / m ² / day is CODcr removal performance gCODcr / m ² / day = BOD removal performance gBOD / m ² / day × 1.5. To be in.

According to the findings of (1) to (3), for example, when the amount of oxygen permeated per day in a unit area of the gas permeation film 21 is 25 gO ₂ / m ² / day or more under atmospheric pressure, the CODcr removal performance is 30 gCODcr. It becomes / m ² / day or more, and BOD removal performance AgBOD / m ² / day becomes 20 g BOD / m ² / day or more. Therefore, by setting the installation area B m ² / m ³ of the gas permeable membrane 21 to 25 m ² / m ³ or more, the value of A × B gBOD / m ³ / day can be increased to 0.5 kg BOD / m ³ / day or more. can do.

When the daily oxygen permeation amount in the unit area of the gas permeation film 21 is 6 gO ₂ / m ² / day or more and less than 25 gO ₂ / m ² / day under atmospheric pressure, the CODcr removal performance is 8 gCOD / m. It becomes ² / day or more, and the BOD removal performance becomes 5.3g BOD / m ² / day or more. Therefore, by setting the installation area B m ² / m ³ of the gas permeable membrane 21 to 94.3 m ² / m ³ or more, the value of A × B gBOD / m ³ / day can be increased to 0.5 kg BOD / m ³ / day or more. Can be.

The findings shown in (1) and (2) above were confirmed by the oxygen supply performance test and the purification treatment performance test described later. The findings shown in (3) above were confirmed by correlating the CODcr concentration and BOD concentration of the wastewater used in the test in advance. In the present invention, the processing performance of the gas permeable membrane 21 is measured at the CODcr concentration, which is easy to analyze.

When installing the gas supply body 10 provided with the gas permeable film 21 in the wastewater treatment tank 51, the dimensions and BOD removal performance of the gas permeable film 21 and the number of gas supply bodies are determined according to the effective volume of the wastewater treatment tank 51.・ By adjusting the installation interval, etc., A × B gBOD / m ³ / day will be 0.5 kgBOD / m ³ / day or more.

When the effective volume of the wastewater treatment tank 51 is 24 m ³ (width 2 m x length 4 m x water depth 3 m), for example, the effective dimensions are width 1.7 m x height 2.7 m and the BOD removal performance is 20 g / m. The gas permeable film 21 which is ² / d is prepared. Then, two gas feeders in which the gas permeable membrane 21 is installed on both the front and back surfaces are installed in the wastewater treatment layer at intervals of 30 mm. By doing so, the installation area of the gas permeable film 21 becomes 1102 m ² (1.7 m × 2.7 m × 3.6 m / 0.03 m × 2), and the installation area of the gas permeable film 21 per effective unit volume of the waste water treatment tank 51. B m ² / m ³ becomes 46 m ² / m ³ (1102 m ^2/24 m ³ ). The value A × B gBOD / m ³ / day obtained by multiplying the BOD removal performance of 20 gBOD / m ² / day and the installation area of the gas permeable film 21 of 46 m ² / m ³ is 920 gBOD / m ³ / day. It will be 0.5 kg BOD / m ³ / day or more.

Alternatively, the two gas feeders may be installed in the wastewater treatment layer at intervals of 50 mm. In this case, the installation area of the gas permeable film 21 is 661 m ² (1.7 m × 2.7 m × 3.6 m / 0.05 m × 2), and the installation area of the gas permeable film 21 per effective unit volume of the wastewater treatment tank 51 is B m ² . / m ³ becomes 28m ² / m ³ (661m ² / 24m ³ ). The value A × B gBOD / m ³ / day obtained by multiplying the BOD removal performance of 20 gBOD / m ² / day and the installation area of the gas permeable membrane 21 of 28 m ² / m ³ is 560 gBOD / m ³ / day. , 0.5 kg BOD / m ³ / day or more.

Even when the base material 211 or the gas permeable non-porous layer 212 is not provided on the gas permeable membrane 21, A × B g BOD / m ³ / day can be 0.5 kg BOD / m ³ / day or more. Therefore, the base material 211 and the gas permeable non-porous layer 212 are not always necessary and may be omitted from the gas permeable membrane 21 (that is, the gas permeable membrane 21 is provided with at least the microorganism support layer 213). good). As shown in the above embodiment, if the gas permeable membrane 21 is made by laminating the microorganism support layer 213, the base material 211, and the gas permeable non-porous layer 212, the following effects can be obtained.

Since the base material 211 is a microporous membrane having high smoothness, the base material 211 can be covered with the gas permeable non-porous layer 212 without causing defects in the gas permeable non-porous layer 212. From this, even if the gas-permeable non-porous layer 212 covering the base material 211 is thin, waterproofness can be obtained. Therefore, the waterproof property of the gas permeable membrane 21 can be enhanced without impairing the air permeability of the gas permeable membrane 21. Further, by covering the base material 211 with the gas-permeable non-porous layer 212, it is possible to prevent the pores of the base material 211 (microporous membrane) from becoming hydrophilic. Therefore, the gas permeable membrane 21 can maintain waterproofness for a long period of time. From the above, if the gas delivery layer 12 is covered with the gas transmission film 21 of the present embodiment, the liquid does not permeate to the gas delivery layer 12 side, and the liquid does not permeate from the gas delivery layer 12 side through the gas transmission layer 21. , Gas can be permeated into the waste water W and supplied. Therefore, the purification performance of the wastewater treatment device 50 is maintained. Further, according to the present embodiment, by inserting the gas delivery layer 12 into the bag formed of the gas transmission film 21, it is possible to easily realize a state in which the gas delivery layer 12 is covered with the gas transmission film 21.

Further, since the gas permeation membrane 21 contains the microorganism support layer 213, the microorganism adheres to the microorganism support layer 213. Therefore, a sufficient amount of gas can be continuously supplied to the microorganism, so that the microorganism is surely continuously activated. Therefore, the purification performance of the wastewater treatment device 50 can be improved.

Further, the gas permeable membrane 21 is laminated in the order of the microbial support layer 213, the base material 211, and the gas permeable non-porous layer 212, so that the outermost layer of the gas permeable membrane 21 in contact with the waste water W is supported by microorganisms. It can be configured by layer 213. Therefore, since the microorganism can be surely attached to the microorganism support layer 213, the microorganism can be surely activated. Therefore, the purification performance of the wastewater treatment device 50 can be surely improved. In particular, when the microorganism contained in the waste water W is an aerobic microorganism, the gas is supplied into the waste water W via the gas permeable membrane 21, so that the aerobic microorganism gathers in the gas permeable membrane 21. Therefore, since many microorganisms adhere to the microorganism support layer 213, the purification performance of the wastewater treatment device 50 is remarkably improved.

[Other embodiments]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention.

For example, in the above embodiment, an example using a planar gas feeder 10 has been described. However, the present invention is not limited to this. For example, the gas feeder 10 may be wound or a gas feeder molded into a cylindrical shape may be used.

In the above embodiment, an example in which the gas delivery layer 12 is inserted through the opening 21b of the bag made of the gas permeable membrane 21 to form the gas feeder 10 has been described. However, the present invention is not limited to this. For example, the gas transmission film 21 may be laminated and adhered to the surface of the gas delivery layer. As the bonding portion, only the outer peripheral portion of the gas permeable film 21 may be bonded, or if the gas can be supplied to the gas permeable film 21, the gas permeable film 21 and the gas delivery layer are all over the entire surface. It may be glued.

Further, installing the gas supply bodies 10 one by one in the wastewater treatment tank 51 requires a long construction time and a high installation cost. Therefore, as shown in FIGS. 10 and 11, a feeder unit 60 that holds a plurality of gas feeders 10 in parallel is manufactured, and one or more of the feeder units 60 are installed inside the wastewater treatment tank 51. You may. By doing so, since many gas feeders 10 can be installed in the wastewater treatment tank 51 in a short time, the construction time and the installation cost can be significantly reduced. Hereinafter, the feeder unit 60 shown in FIGS. 10 and 11 will be described in detail (FIG. 10 is a perspective view showing the feeder unit 60, and FIG. 11 is a side view showing the feeder unit 60).

In addition to the plurality of gas feeders 10, the feeder unit 60 includes a pair of unit frames 61, 61, four through members 62, and a plurality of spacers 63 (FIG. 11).

The unit frames 61, 61 have a rectangular ring shape and are arranged so as to face each other at intervals. The through member 62 is a linear steel material, and the four corners of the pair of unit frames 61, 61 are connected by four through members 62. Eyelets 64 are attached to the four corners of each of the gas supply bodies 10, and the through member 62 is sequentially passed through the eyelets 64 of each gas supply body 10, so that each gas supply body 10 has a through member 62. It is held in a state of being lined up in the extending direction of the through member 62. The spacer 63 is a tubular body through which the through member 62 can be inserted. In the feeder unit 60, the spacer 63 is ringed in the range of the through member 62 extending between the two adjacent gas feeders 10, so that the distance between the two gas feeders 10 and 10 is increased by the spacer 63. Maintained in width. Further, by changing the length of the spacer 63, the intervals between the gas feeders 10 and 10 can be changed.

FIG. 12 is a vertical sectional view of a wastewater treatment tank 51 including a feeder unit 60. FIG. 13 is a plan view of the wastewater treatment tank 51 including the feeder unit 60.

Since the feeder unit 60 has a plurality of hollow gas feeders 10, when the feeder unit 60 is installed in the wastewater treatment tank 51, a large buoyancy acts on the feeder unit 60. Therefore, in order to prevent the feeder unit 60 from floating, the fixing bracket 70 and the floating prevention member 71 shown in FIGS. 10 to 13 are used.

The fixing bracket 70 is an L-shaped steel material and has a substrate 70a and a vertical plate 70b extending vertically from the substrate 70a. The substrate 70a is fixed to the bottom of the wastewater treatment tank 51 (see FIGS. 11 and 12). The levitation prevention member 71 is a steel material whose tip portion 71a is curved in an arc shape, and the base end portion 71b is fixed to the vertical surface of the fixing bracket 70. Then, by hooking the passing member 62 on the tip end portion 71a of the levitation prevention member 71, the feeder unit 60 is prevented from levitation.

When the above-mentioned feeder unit 60 is used, the BOD removal performance, effective dimensions, and spacing of the gas feeder 10 and the effective dimensions, installed number of feeder units 60, depending on the effective volume of the wastewater treatment tank 51, are used. By appropriately setting, the value obtained by multiplying the BOD removal performance AgBOD / m ² / day of the gas permeable film 21 and the installation area Bm ² / m ³ of the gas permeable film 21 is 0.5 kgBOD / m ³ / day. That is all.

For example, when the effective volume of the wastewater treatment tank 51 is 24 m ³ (width 2 m × length 4 m × water depth 3 m), the effective dimensions are width 1.6 m × height 2.6 m × length 1.8 m. Prepare a gas feeder 10 having a gas permeable film 21 having a BOD removal performance of 20 gBOD / m ² / d installed on both the front and back surfaces. Then, a feeder unit 60 having effective dimensions of 1.7 m in width × 2.7 m in height × 1.8 m in length and holding the gas feeder 10 at intervals of 30 mm was manufactured, and two of the feeder units 60 were used as waste water. It is installed in the processing tank 51. As described above, the surface area of the gas permeable film 21 becomes 998 m ² (1.6 m × 2.6 m × 1.8 m / 0.03 m × 2 × 2), and the installation area of the gas permeable film 21 per effective volume of the wastewater treatment tank 51. B m ² / m ³ becomes 41m ² / m ³ (998m ² / 24m ³ ). Therefore, the value A × B gBOD / m ³ / day obtained by multiplying the BOD removal performance of 20 gBOD / m ² / day and the installation area of the gas permeable membrane 21 of 41 m ² / m ³ is 820 gBOD / m ³ / day. , 0.5 kg BOD / m ³ / day or more. The "width 1.7 m of the feeder unit 60" corresponds to the width of the unit frames 61 and 61, and the "height 2.7 m of the feeder unit 60" corresponds to the height of the unit frames 61 and 61. The “length 1.8 m of the feeder unit 60” corresponds to the length of a straight line connecting the opposing corners of the unit frames 61 and 61.

When the feeder unit 60 having N gas feeders 10 is installed in the wastewater treatment tank 51, it is 90% as compared with the case where the N gas feeders 10 are installed in the wastewater treatment tank 51 as they are. The installation area of the gas permeable membrane 21 is reduced to some extent. Therefore, when the feeder unit 60 is used, in order to obtain the same treatment performance as the activated sludge method, the installation area of the gas permeable membrane 21 per unit volume per effective volume of the wastewater treatment tank 51 is 28 m ² / m. It is preferably ³ or more. 28m ² / m ³ is a numerical value obtained by the calculation of 25m ² / m ³ / 0.9.

Further, when the above-mentioned feeder unit 60 is used, the feeder unit 60 is installed in the wastewater treatment tank 51 so that the gas feeder 10 included in the feeder unit 60 is substantially parallel to the flow of wastewater. Is desirable. By doing so, the flow of wastewater is not obstructed by the gas feeder 10, and the contact between the wastewater and the microorganisms grown on the gas permeation membrane 21 can be improved.

Further, as shown in FIGS. 12 and 13, a diving dam 80 for directing the wastewater downward is installed in the vicinity of the inflow port 51a inside the wastewater treatment tank 51, and the outflow port inside the wastewater treatment tank 51 is installed. It is desirable to install an overflow weir 81 in the vicinity of 51b to allow wastewater to overflow evenly. By doing so, the wastewater is uniformly dispersed and flows between the gas permeable membranes 21 (in FIGS. 12 and 13, the flow of the wastewater is indicated by an arrow).

When the above-mentioned submerged weir 80 and overflow weir 81 are provided, it is preferable that the submerged weir 80 and overflow weir 81 extend over the entire width of the wastewater treatment tank 51, as shown in FIG. .. By doing so, the wastewater is uniformly dispersed and flows between the gas permeable membranes 21 in the entire wastewater treatment tank 51. As shown in FIG. 13, when the inflow port 51a is formed on one of the two opposite side walls 510 and 510 of the wastewater treatment tank 51 and the outflow port 51b is formed on the other side, the two side walls are formed. The direction orthogonal to the facing direction (direction in which the wastewater flows) of 510 and 510 corresponds to the above-mentioned "width direction of the wastewater treatment tank 51".

Further, as shown in FIGS. 14 and 15, the feeder unit 60 may be installed in multiple stages in the flow direction of wastewater (direction facing the side walls 510 and 510). In this case, it is preferable to install the overflow weir 81 and the submerged weir 80 not only in the vicinity of the inflow port 51a and the outflow port 51b but also in the middle portion of the wastewater treatment tank 51 under the wastewater flow (see FIG. 15). .. By doing so, the flow of wastewater can be made uniform again. Note that FIG. 15 shows an example in which the overflow weir 81 and the submersible weir 80 are installed only between the two feeder units 60 and 60 in the middle portion of the wastewater treatment tank 51, but other wastewater. An overflow weir 81 and a submersible weir 80 may also be installed between the two feeder units 60, 60 adjacent to each other in the flow direction. Further, not only when the feeder unit 60 is installed in multiple stages, but also when a plurality of gas feeders 10 are arranged side by side in the flow direction of the wastewater, the overflow weir 81 is submerged in the intermediate portion of the wastewater treatment tank 51 under the wastewater flow. A weir 80 may be installed.

Next, the oxygen supply performance test and the purification treatment performance test conducted by the inventors of the present application will be described. Table 1 below shows the specifications and test results of the gas permeable membrane 21 used in the above test.

The gas permeable membranes of Examples 1 to 7 are laminated in the order of the microorganism support layer 213, the base material 211, and the gas permeable non-porous layer 212. The gas permeable membranes of Examples 8 and 9 are obtained by laminating the microorganism support layer 213 and the base material 211. The gas permeable membranes of Examples 10 to 13 are obtained by laminating a microorganism support layer 213 and a gas permeable non-porous layer 212.

In Examples 1 to 13, the polyolefin non-woven fabric contained in Sekisui Chemical Co., Ltd.'s Serpore NW07H was used as the microorganism support layer 213.

In Examples 1 to 8, the fine pore membrane also contained in Cellpore NW07H was used as the base material 211.

In Example 9, the fine pore film contained in Sekisui Chemical's Cellpore NW08 was used as the base material 211.

In Examples 1 to 5, a mixed solution of a methylvinyl-based silicon resin, a cross-linking agent, a platinum-based catalyst, or the like is applied onto the base material 211 using a bar coater, and then allowed to stand in an atmosphere of 70 ° C. for 1 hour. By placing it, the gas permeable non-porous layer 212 is laminated on the base material 211. As the silicon resin, the model number "NC1910" manufactured by Asahi Kasei Wacker Silicone Co., Ltd. was used.

In Examples 6 and 7, a urethane resin of model number "Heimlen Y-237NS" manufactured by Dainichiseika Kogyo Co., Ltd. was used instead of the silicon resin in order to form the gas permeable non-porous layer 212.

In Example 10, PVB was used to form the gas permeable non-porous layer 212. In Examples 11 and 12, the gas permeable non-porous layer 212 was formed using LDPE. In Example 13, PP was used to form the gas permeable non-porous layer 212.

<Oxygen supply performance test>
In the oxygen supply performance test, a gas permeable membrane was placed on one side of a cube with an inner size of 7 cm, and a sealed evaluation tank was used. Then, the rotor for the stirrer and the ion-exchanged water were put in the evaluation tank. Sodium sulfite was added at 100 mg / L and cobalt chloride was added at 1.5 mg / L or more to the ion-exchanged water. Then, while continuously measuring the oxygen concentration in the evaluation tank, the stirrer "HE-20GB" manufactured by Koike Precision Instruments Mfg. Co., Ltd., the rotation speed was set to the scale 7 in the HIGH range, and the mixture was stirred.

The oxygen supply performance was evaluated in an environment of 23 ° C to 27 ° C. From the time-series data of the measured oxygen concentration, an approximate straight line is obtained from the correlation with the common logarithm Y = log10 (Cs-C) of the oxygen deficiency with respect to time t (h), and the slope Z of Y with respect to time t of the approximate straight line. Asked. Cs is the saturated oxygen concentration of the liquid phase at the measurement temperature T, and C is the oxygen concentration measurement value of the liquid phase at the measurement time t. From the slope Z, the oxygen supply rate Q (gO ₂ / m ² / day) was calculated according to Eq. (2).

[Equation 2]
Q = -2.303 x 24 x 0.00884 x V x Z x (1.028) ^ (20-T) / S (2)
V: Liquid volume used for measurement (L), S: Effective area of gas permeable film 21 used for measurement (m ² ), T: Mean value of liquid temperature at the time of measurement (° C)

<Purification treatment performance test>
In the test for confirming the processing performance, a gas permeable membrane 21 was placed on one side surface of a cube having an inner size of 7 cm, and a sealed evaluation tank was used. Then, in the evaluation tank, organic matter-containing water containing proteins, carbohydrates, etc. having a CODcr concentration of 1.3 g / L and appropriate nutrients, and soil microorganisms as microorganisms responsible for the decomposition of organic matter were placed.

All the liquid in the tank was discharged every 3 days, and the organic matter-containing water was replaced. The effective area of the gas permeable membrane 21 was 7x7 cm. The organic-containing water was stirred with a stirrer.

The evaluation tank was installed in a constant temperature bath at 30 ° C. Prior to the measurement of CODcr concentration, a 4-week acclimatization period was provided. The CODcr concentration of the organic matter-containing water 3 days after the replacement of the organic matter-containing water was measured, and the organic matter removal rate was obtained from the CODcr concentration A (mg / L) before the treatment and the CODcr concentration B (mg / L) after the treatment. R (%) was calculated according to the equation (3).

[Equation 3]
R = (1-B / A) x 100 (3)

From the test results shown in Table 1, the following (1) and (2) were confirmed.
(1) When the oxygen supply rate of the gas permeation membrane 21 is 25 gO ₂ / m ² / day or more, the CODcr removal performance is 30 gCODcr / m ² / day or more.
(2) When the oxygen supply rate of the gas permeation membrane 21 is 6 gO ₂ / m ² / day or more and less than 25 gO ₂ / m ² / day, the CODcr removal performance is 8 gCODcr / m ² / day or more.

In addition, the inventors of the present application conducted a test to confirm the short-term pressure resistance and long-term leak performance of the gas permeable membrane of the embodiment of the present invention. Table 2 below shows the specifications and test results of the gas permeable membrane 21 used in this test.

<Example 1>
In Example 1, the microorganism support layer 213, the base material 211, and the gas permeable non-woven fabric 212 are laminated in this order, and a microporous film contained in Sekisui Chemical Co., Ltd.'s Cellpore NW07H is used as the base material 211. , The polyolefin non-woven fabric contained in the above-mentioned Cellpore NW07H was used as the microorganism support layer 213. (The Cellpore NW07H has a three-layer structure of a non-woven fabric, a microporous film, and a non-woven fabric. Of these, one of the non-woven fabrics is used as the microorganism support layer 213. The microporous polyolefin membrane was used as the substrate 211). The thickness of the base material 211 was 90 um. The basis weight of the microbial support layer 213 was 10 g / m ² , and the thickness was 25 um.

Further, in Example 1, a mixed solution of a methylvinyl-based silicon resin, a cross-linking agent, a platinum-based catalyst, or the like is applied onto the base material 211 using a bar coater, and then allowed to stand in an atmosphere of 70 ° C. for 1 hour. By doing so, the gas permeable non-porous layer 212 is laminated on the base material 211. As the silicon resin, the model number "NC1910" manufactured by Asahi Kasei Wacker Silicone Co., Ltd. is used, and the basis weight of the silicon resin after curing is 20 g / m ² .

<Example 2>
In Example 2, a urethane resin of model number "Heimlen Y-237NS" manufactured by Dainichiseika Kogyo Co., Ltd. was used instead of the silicon resin to form the gas permeable non-porous layer 212, and the basis weight of the resin was used. The same as in Example 1 except that the value was set to 10 g / m ² .

<Example 3>
Example 3 is the same as that of Example 1 except that the basis weight of the resin constituting the gas permeable non-porous layer 212 is 40 g / m ² .

<Example 4>
Example 4 is the same as that of Example 1 except that the basis weight of the resin constituting the gas permeable non-porous layer 212 is 80 g / m ² .

<Example 5>
Example 5 is the same as that of Example 3 except that a microporous film (thickness 40 um) manufactured by 3M Co., Ltd. is used as the base material 211.

<Example 6>
Example 6 is the same as that of Example 4 except that Exepol E BSPBX-4 (thickness 23 μm) manufactured by Mitsubishi Plastics Co., Ltd. is used as the base material 211.

<Example 7>
Example 7 is the same as that of Example 3 except that Elves SO203WDO manufactured by Unitika Ltd. (with a basis weight of 20 g / m2) is used as the microorganism support layer 213.

<Example 8>
Example 8 is the same as that of Example 3 except that Elves T0503WDO (weight: 50 g / m2) manufactured by Unitika Ltd. is used as the microorganism support layer 213.

<Example 9>
Example 9 is the same as that of Example 1 except that the basis weight of the resin constituting the gas permeable non-porous layer 212 is 100 g / m ² .

<Example 10>
Example 10 is the same as that of Example 5 except that Elves T0703WDO manufactured by Unitika Ltd. (with a basis weight of 70 g / m ² ) is used as the microorganism support layer 213.

<Example 11>
Example 11 is the same as that of Example 1 except that the basis weight of the resin constituting the gas permeable non-porous layer 212 is 8 g / m ² .

<Example 12>
Example 12 is the same as that of Example 1 except that the gas permeable non-porous layer 212 is continuously produced by a reverse roll coater and a heating device associated therewith.

<Example 13>
Example 13 is the same as Example 5 except that the gas permeable non-porous layer 212 is continuously produced by a slit coater and a heating device associated therewith.

<Example 14>
Example 14 is the same as that of Example 1 except that an ultraviolet curable silicone resin mixture is applied onto the base material 211 using a reverse roll coater and then cured by ultraviolet irradiation.

<Example 15>
In Example 15, only a moisture-permeable film made of Sekisui Film and a microporous membrane of Cellpore NW07H were used as the base material 211, and a resin layer was laminated on the microporous membrane by the same method as in Example 2. Example 10 in which the polyolefin non-woven fabric contained in the Celpore NW07H is laminated on the resin layer, allowed to stand in an atmosphere of 70 ° C. for 1 hour, and the base material 211, the gas permeable resin layer, and the microorganism support layer 213 are in that order. Gas permeable film was obtained.

<Comparative Example 1>
In Comparative Example 1, a polyester-based non-woven fabric, model number “Marix 82607WSO” manufactured by Unitika Ltd. was used as the base material 211, and a resin layer was laminated on the non-woven fabric by the same method as in Example 1. The basis weight of the resin in the gas-permeable non-porous layer was 20 g / m ² .

<Short-term pressure resistance>
The short-term test was carried out by measuring the short-term withstand pressure (leak pressure).
Specifically, the short-term withstand pressure was measured mainly by a method obtained by modifying a part of JIS K 6404-7: 1999, A21: high water pressure-small sample method (dynamic pressure method). The short-term pressure resistance is the value of the pressure gauge when water first appears through the test piece. The differences from the high water pressure-small sample method (dynamic pressure method) are described below. A support non-woven fabric (Unitika Marix 82607WSO) was layered on the surface of the gas permeable membrane, which is the test piece, opposite to the surface on which the water pressure is applied. The water used for the test was ion-exchanged water containing food coloring so that the water that appeared through the test piece could be easily confirmed. The speed at which the water pressure was increased was 0.1 MPa per minute.

<Oxygen supply performance, purification treatment performance>
In this test as well, the oxygen supply rate Q (gO ₂ / m ² / day) and the organic matter removal rate R (%) were calculated by the same method as the oxygen supply performance test and purification treatment performance test described above.

<Long-term leak performance>
The long-term leak performance was evaluated by visually observing the air-side surface of the gas permeable membrane placed in the wastewater treatment device, or by confirming the presence or absence of water leakage using cobalt chloride paper.

Further, when Examples 1 to 15 having the microorganism support layer and Comparative Example 16 having no microorganism support layer are compared, the organic matter removal rates of Examples 1 to 15 are all higher than the organic matter removal rate of Comparative Example 1. Was also expensive. As a result, it was confirmed that the purification performance of the wastewater treatment device can be improved by providing the microbial support layer on the gas permeable membrane.

In Comparative Example 1 in which the base material was composed of a PET / PE-based non-woven fabric, the short-term pressure resistance was 0.05 MPa. Further, in the wastewater treatment apparatus using Comparative Example 1, water leakage to the air side of the sheet was observed after 2 months, and the long-term leak performance was poor. Moreover, due to water leakage, the purification treatment performance of Comparative Example 1 could not be measured.

On the other hand, in Examples 1 to 15 in which the base material was composed of a microporous membrane, the short-term pressure resistance was 0.2 MPa or more, which was higher than that of Comparative Example 1. Further, in the wastewater treatment apparatus using Examples 1 to 15, no water leakage to the air side of the sheet was confirmed for a long period of time, and the long-term leakage performance was good. From the above, it was confirmed that the waterproof property can be improved by providing the base material composed of the microporous membrane on the gas permeable membrane. From this, it is shown that if the short-term pressure resistance is 0.2 MPa or more, the long-term pressure resistance can be secured.

Further, comparing Examples 1 and 3 to 14 in which the resin of the gas permeable non-porous layer is silicon and Examples 2 and 15 in which the resin of the gas permeable non-porous layer is urethane, Examples 1 and 3 are compared. The oxygen supply performance of each of 14 to 14 was higher than the oxygen supply performance of Examples 2 and 15. As a result, it was confirmed that the oxygen supply performance of the gas permeable membrane can be improved by using silicon as the resin for the gas permeable non-porous layer.

10 Gas feeder 12 Gas delivery layer 21 Gas permeable membrane 50 Wastewater treatment device 51 Wastewater treatment tank 51a Inlet 51b Outlet 60 Supply unit 80 Submersible weir 81 Overflow weir

Claims (8)

A wastewater treatment device that activates microorganisms in wastewater by supplying oxygen that has permeated through a gas permeable membrane to the wastewater stored inside the wastewater treatment tank, and purifies the wastewater by the activity of the microorganisms.
A wastewater treatment tank having an inflow port for inflowing wastewater and an outflow port for outflowing wastewater, in which the inflow port and the outflow port are arranged so as to face each other.
It is a hollow flat plate-shaped member having an opening at the upper end portion, and is provided with a gas feeder provided with the gas permeable membrane.
The gas feeder takes in air near the opening from the opening and supplies it to the wastewater of the wastewater treatment tank through the gas permeable membrane.
The daily oxygen permeation amount in the unit area of the gas permeation film is 25 gO ₂ / m ² / day or more under atmospheric pressure, and the installation area B m of the gas permeation film per effective unit volume of the wastewater treatment tank. ² / m ³ is 25 m ² / m ³ or more, or the amount of oxygen permeation per day in the unit area of the gas permeable membrane is 6 gO ₂ / m ² / day or more 25 gO ₂ / under atmospheric pressure. It is less than m ² / day, and the installation area B m ² / m ³ of the gas permeable membrane per effective unit volume of the wastewater treatment tank is 94.3 m ² / m ³ or more, so that the said per unit area. BOD removal performance by gas permeable film BOD removal rate A × which is a value obtained by multiplying Ag BOD / m ² / day by the installation area B m ² / m ³ of the gas permeable film per effective unit volume of the waste water treatment tank. B kgBOD / m ² / day is 0.5 kgBOD / m ² / day or more ,
The gas supply body is a wastewater treatment apparatus, characterized in that the gas permeable membrane is arranged inside the wastewater treatment tank so as to extend in a direction in which the inlet and the outlet face each other . The gas feeder includes the gas permeable membrane and a gas delivery layer which is a hollow plate-like member having a gas flow path.
The air near the opening is supplied to the upper end of the gas delivery layer through the opening, and the air supplied to the upper end of the gas delivery layer flows through the gas flow path and permeates the gas. The wastewater treatment apparatus according to claim 1, which is supplied into wastewater through a membrane. A plurality of the gas feeders are arranged side by side inside the wastewater treatment tank.
The wastewater treatment apparatus according to claim 1 or 2 , wherein the distance between two adjacent gas feeders is 15 mm or more and 50 mm or less. It has a feeder unit that holds a plurality of the gas feeders in parallel, and has a feeder unit.
The wastewater treatment apparatus according to any one of claims 1 to 3 , wherein one or more of the feeder units are installed inside the wastewater treatment tank. The daily oxygen permeation amount in the unit area of the gas permeation film is 25 gO ₂ / m ² / day or more under atmospheric pressure, and the installation area of the gas permeation film B m ² per unit volume of the wastewater treatment tank. The wastewater treatment apparatus according to any one of claims 1 to 4, wherein / m ³ is 28 m ² / m ³ or more. The claim is characterized in that a diving weir is installed in the vicinity of the inflow port inside the wastewater treatment tank, and an overflow weir is installed in the vicinity of the outflow port inside the wastewater treatment tank. The wastewater treatment apparatus according to any one of 1 to 5 . The wastewater treatment apparatus according to any one of claims 1 to 6 , wherein an overflow weir and a submersible weir are installed in the middle portion of the wastewater treatment tank. The wastewater treatment apparatus according to any one of claims 1 to 7 , wherein the short-term pressure resistance of the gas permeable membrane is 0.2 Mpa or more.

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