JP7492418B2 - Wastewater treatment system and wastewater treatment method - Google Patents

Description

This relates to a wastewater treatment system that utilizes the action of aerobic microorganisms to decompose organic matter in the water and purify the wastewater.

Aerobic microbial wastewater treatment equipment is widely used as a method for treating organic wastewater. However, aeration using an aeration tube has low oxygen dissolution efficiency and requires aeration at a pressure higher than the water pressure applied to the aeration tube, resulting in high electricity costs for the blower.

Wastewater treatment equipment is being considered that treats wastewater by attaching microorganisms to a gas supply body that is permeable to gas but not to liquid. This equipment can reduce the pressure applied to the air supply, making it possible to reduce electricity costs. Examples of such gas supplies are disclosed in Patent Documents 1 and 2.

Patent No. 3743771 Patent No. 4680504

In aerobic microbial wastewater treatment systems that use a gas supply, condensed water is generated inside the gas supply due to the penetration of water vapor through the gas supply and the condensation of water vapor in the supplied air. This causes part of the gas supply flow path to become clogged, reducing the supply efficiency.

One way to deal with this type of condensation is to provide a liquid delivery section that will drain the condensation from inside the gas supply body.

However, in a wastewater treatment device equipped with multiple gas suppliers, if you try to pump water using one pump, the gas will be sucked from the gas supplier that has already pumped the water, making it difficult to pump out the condensed water from the entire module.

The wastewater treatment system according to a first aspect is a wastewater treatment system that purifies wastewater by utilizing the action of microorganisms,
A gas supply body used by immersing in the wastewater, the gas supply body including a waterproof air-permeable membrane, and the gas supplied to an internal space partitioned by the waterproof air-permeable membrane is supplied to the microorganisms in the wastewater outside the waterproof air-permeable membrane; and
A liquid delivery unit that discharges fluid from the internal spaces of the plurality of gas supply bodies;
Equipped with
The liquid delivery unit includes:
A plurality of liquid supply pipes respectively connected to the internal spaces of the plurality of gas supply bodies;
a manifold connected to the plurality of liquid delivery pipes;
a suction pump connected to the manifold;
When the suction pump discharges the fluid in the internal space of the gas supplier to the outside, the liquid in the internal space is discharged to the outside by utilizing negative pressure generated by a flow pressure loss of the gas.
The wastewater treatment system of a second aspect is the system of the first aspect, wherein the internal cross-sectional area of the liquid transfer pipe is ¹⁰ mm2 or less.
A wastewater treatment system according to a third aspect is the system according to the first or second aspect, wherein the liquid transfer pipe includes a pressure loss generating section that generates a flow pressure loss of gas.
A wastewater treatment system according to a fourth aspect is the system according to any one of the first to third aspects, wherein the pressure loss generating portion is an orifice portion in the liquid feed pipe, a narrowed portion in the liquid feed pipe, a curved portion of the liquid feed pipe, or a portion in the liquid feed pipe where a communicating porous member is disposed.
A wastewater treatment system according to a fifth aspect is the system according to any one of the first to fourth aspects, further comprising an air supply unit that supplies gas to an internal space of the gas supplier.
A wastewater treatment system according to a sixth aspect is the system according to the fifth aspect, wherein the air supply unit includes an air supply pipe connected to an internal space of the gas supplier,
The air supply pipe is provided separately from the liquid supply pipe.
A wastewater treatment system according to a seventh aspect is the system according to the fifth aspect, wherein the air supply unit includes an air supply pipe connected to an internal space of the gas supplier,
The air supply pipe is common to the liquid supply pipe.
A wastewater treatment method according to an eighth aspect is a wastewater treatment method for purifying wastewater by utilizing the action of microorganisms using a wastewater treatment device,
The wastewater treatment device comprises:
A gas supply body used by immersing in the wastewater, the gas supply body including a waterproof air-permeable membrane, and the gas supplied to an internal space partitioned by the waterproof air-permeable membrane is supplied to the microorganisms in the wastewater outside the waterproof air-permeable membrane; and
A liquid delivery unit that discharges fluid from the internal spaces of the plurality of gas supply bodies;
Equipped with
The liquid delivery unit includes:
A plurality of liquid supply pipes respectively connected to the internal spaces of the plurality of gas supply bodies;
a manifold connected to the plurality of liquid delivery pipes;
a suction pump connected to the manifold;
When the suction pump discharges the fluid in the internal space of the gas supplier to the outside, the liquid in the internal space is discharged to the outside by utilizing negative pressure generated by a flow pressure loss of the gas.

According to the wastewater treatment system disclosed herein, when the suction pump discharges the fluid in the internal spaces of multiple gas supply bodies to the outside, the negative pressure generated by the loss of gas flow pressure is utilized to discharge the liquid in the internal spaces to the outside, so that the negative pressure in the manifold is maintained even after the water in some of the gas supply bodies has been pumped out, making it possible to pump out the water in all of the gas supply bodies.

1 is a vertical cross-sectional view of a wastewater treatment system 50 according to a first embodiment. FIG. 2 is a vertical cross-sectional view of the wastewater treatment system 50 of the first embodiment, taken in a direction 90° different from that of FIG. 1 is a vertical cross-sectional view of a gas supplier 10 of a first embodiment. FIG. 2 is a perspective view of the gas delivery layer 12 constituting the gas supplier 10 of the first embodiment. FIG. 1 is a diagram showing a schematic diagram of a state in which microorganisms decompose organic matter in wastewater W using the gas supplier 10 of the first embodiment. FIG. 1 is a diagram showing a state in which water has accumulated in the internal space of the gas supply body 10a, 10b of the first embodiment and is being discharged. FIG. FIG. 6B is a diagram showing the state of the gas supply bodies 10a and 10b of the first embodiment after FIG. 6A. 4 is a diagram showing an orifice portion 47a in the liquid supply tube 41 of the first embodiment. FIG. 4 is a diagram showing a multiple-hole orifice portion 47b in the liquid feed tube 41 of the first embodiment. FIG. 13 is a diagram showing a constriction portion 47c in the liquid supply tube 41 of the first embodiment. FIG. 13 is a diagram showing a curved portion 47d in the liquid supply tube 41 of the first embodiment. FIG. 4 is a diagram showing a portion where a communicating porous member 47e is arranged in the liquid supply pipe 41 of the first embodiment. FIG. FIG. 11 is a vertical cross-sectional view of a wastewater treatment system 50a according to a second embodiment.

First Embodiment
(Wastewater treatment device 100)
The wastewater treatment device 100 of this embodiment utilizes the action of aerobic microorganisms contained in the wastewater to decompose at least one organic matter or nitrogen source in the wastewater, thereby purifying the wastewater. As shown in FIG. 1, the wastewater treatment device 100 includes a wastewater treatment tank 51 and a wastewater treatment system 50.

(Wastewater treatment tank 51)
1 or 2, the wastewater treatment tank 51 is a bottomed container in which wastewater W is stored, and is provided with an inlet 51a and an outlet 51b. For example, the inlet 51a and the outlet 51b may be provided on opposite side surfaces.

In this embodiment, the inlet 51a and the outlet 51b are always open. The wastewater W is supplied continuously or intermittently from the inlet 51a to the outlet 51b, which is located opposite the inlet 51a (the dashed arrow in Figure 2 indicates the flow of the wastewater W).

The volume of the wastewater treatment tank 51 is not particularly limited, but may be, for example, from ¹ m3 to ^{10,000 m3} .

(Wastewater Treatment System 50)
The wastewater treatment system 50 includes a supplier unit 52 , an air supply section 30 , and a liquid supply section 40 .

(Supplier unit 52)
As shown in Fig. 1, the supplier unit 52 is a unitized gas supplier 10, and is disposed inside the wastewater treatment tank 51. In Fig. 1, the supplier unit 52 is composed of a plurality of gas suppliers 10 arranged in parallel. The supplier unit 52 is disposed such that, when in use, all of the gas suppliers 10 except for their upper end portions are immersed in the wastewater W.

(Gas supplier 10)
Each gas supplier 10 is a structure that supplies gas supplied from the opening 21b into the wastewater W in a state where it is immersed in the wastewater W of the wastewater treatment tank 51. As shown in FIG. 3, the gas supplier 10 includes a gas sending layer 12 and a waterproof gas-permeable membrane 21. A part of the air sending pipe 31 of the air sending section 30 is inserted into the internal space of the gas supplier 10 via the opening 21b. Gas (air, oxygen) is supplied from the air sending section 30 to the internal space of the gas supplier 10. In addition, a part of the liquid sending pipe 41 of the liquid sending section 40 is disposed in the internal space of the gas supplier 10. Condensed water generated in the gas sending layer is discharged from the internal space of the gas supplier 10 to the outside via the liquid sending section 40. In this embodiment, the opening 21b allows air and gas to enter and exit the internal space of the gas supplier 10 in addition to the air sending pipe 31 and the liquid sending pipe 41. The opening 21b may be sealed so that air and gas other than the air supply pipe 31 and the liquid supply pipe 41 cannot enter or exit.

As shown in FIG. 2, each gas supply body 10 is a flat plate-shaped member and is arranged so that the surface is expanded along the vertical direction (depth direction) and the horizontal direction (horizontal direction). This ensures an efficient contact area with the wastewater W. In addition, by arranging each gas supply body 10 so that the side of each gas supply body 10 is parallel to the straight line connecting the inlet 51a and the outlet 51b, the wastewater W supplied from the inlet 51a to the wastewater treatment tank 51 flows smoothly toward the outlet 51b. The number of gas supplies 10 constituting the supply body unit 52 does not necessarily have to be multiple, and may be single. The gas supply body may also be spiral-shaped or hollow fiber-shaped. In the case of a spiral shape, a gas supply body is arranged inside as in the case of a flat plate, and an air supply section and a liquid supply section are inserted into the gas supply body. In the case of a hollow fiber shape, if the strength of the hollow fiber itself can maintain the internal space, a gas supply body may not be required. The air supply section and liquid supply section are inserted inside the header, which bundles multiple hollow fibers.

If the spacing between the gas supply bodies 10 is defined as the spacing between the outer surfaces of two adjacent gas supply bodies 10, not including the thickness of the gas supply body 10, then the spacing between the gas supply bodies 10 is preferably 5 mm or more and 200 mm or less. If the spacing between the gas supply bodies 10 is less than 5 mm, there is a risk of clogging due to microorganisms growing on the waterproof air-permeable membrane 21. If the spacing between the gas supply bodies 10 exceeds 200 mm, the efficiency of contact with the wastewater may decrease, making it difficult to improve the wastewater treatment performance. In order to reliably avoid the above problems, it is more preferable to set the spacing between the gas supply bodies 10 to 15 mm or more and 50 mm or less.

Figure 3 is a vertical cross-sectional view of the gas supply body 10. As shown in Figure 3, the gas supply body 10 includes a gas sending layer 12 and a waterproof gas-permeable membrane 21, and the gas sending layer 12 is disposed in a bag formed by the waterproof gas-permeable membrane 21. The bag is formed by overlapping two waterproof gas-permeable membranes 21, 21 and bonding the three ends of these waterproof gas-permeable membranes 21, 21, and has an opening 21b (see Figure 3) at the upper end (the end on the gas supply side of the gas sending layer 12). The gas sending layer 12 is inserted into the bag through the opening 21b, so that the outer periphery of the gas sending layer 12 is covered by the waterproof gas-permeable membrane 21. The position or shape of the opening 21b is not limited, and for example, a part of each end (including the top side, bottom side, and horizontal side (vertical line) of the bag) may be an opening.

(Air supply unit 30)
The gas supply unit 30 supplies gas to the internal space of the gas supplier 10. The gas supply unit 30 includes a blower 36, a manifold 35, and an air supply pipe 31. The air supply pipe 31 is a pipe that sends air (oxygen) sent from the blower 36 into the inside of the gas supplier 10. The manifold 35 is connected to the blower 36 at one end and to the multiple air supply pipes 31 at the other end.

The gas supplied to the wastewater W via the gas supply 10 is a gas containing oxygen to promote activation of aerobic microorganisms in the wastewater W. Specifically, it may be air or pure oxygen. In the illustrated example, gas is supplied from the blower 36 to the opening 21b. From the viewpoint of keeping manufacturing costs low, it is also possible to directly introduce atmospheric air into the gas supply 10 from the opening 21b without using the blower 36.

(Waterproof and breathable membrane 21)
The waterproof air-permeable membrane 21, when immersed in the liquid (wastewater) so that the outermost layer is in contact with the liquid (wastewater), allows oxygen supplied to the inside (gas-sending layer 12 side) to permeate outward, thereby supplying oxygen into the liquid (wastewater). When the gas supplier 10 is immersed in the wastewater treatment tank 51, the waterproof air-permeable membrane 21 has the property of allowing air to permeate from the inside (gas-sending layer 12) to the outside (wastewater W) and not allowing wastewater to permeate from the outside (wastewater W) to the inside (gas-sending layer 12). As a result, aerobic microorganisms in the wastewater W gather on the surface 21a of the waterproof air-permeable membrane 21 to which air (oxygen) is continuously supplied, as shown in FIG. 5. Thus, microorganisms attach to the surface 21a of the waterproof air-permeable membrane 21, forming a biofilm 214. Then, due to the action of the microorganisms contained in the wastewater W or held on the surface 21a, the microscopic solid organic matter or nitrogen compounds dissolved or dispersed in the water are decomposed, and the wastewater is purified.

Specifically, as shown in FIG. 3, the waterproof air-permeable membrane 21 includes a substrate 211, a gas-permeable non-porous layer 212, and a microorganism support layer 213. In the illustrated example, the waterproof air-permeable membrane 21 is laminated in the order of the substrate 211, the gas-permeable non-porous layer 212, and the microorganism support layer 213. The microorganism support layer 213 is the outermost layer that contacts the wastewater W. Note that, unlike the illustrated example, the waterproof air-permeable membrane 21 may be laminated in the order of the gas-permeable non-porous layer 212, the substrate 211, and the microorganism support layer 213.

(Substrate 211)
The substrate 211 is a microporous film formed from a thermoplastic resin. The microporous film is a film having a large number of fine through holes. The material of the substrate 211 may include a polymer material selected from fluororesins including polyolefin, polystyrene, polysulfone, polyethersulfone, polyarylsulfone, polymethylpentene, polytetrafluoroethylene, and polyvinylidene fluoride, silicone-based polymers including polybutadiene and poly(dimethylsiloxane), and copolymers of these materials.

The method for producing the substrate 211, which is a microporous membrane, is not particularly limited, but the substrate 211 can be produced by, for example, a phase separation method, a stretching method, a melting recrystallization method, a powder sintering method, a foaming method, or a solvent extraction. The substrate 211 may also be a self-organized honeycomb microporous membrane.

The thickness of the substrate 211 is preferably 10 μm to 500 μm, and more preferably 50 μm to 200 μm. The thickness of the substrate 211 is a value measured according to JIS1913:2010 General Nonwoven Fabric Test Method 6.1 Thickness Measurement Method.

The pore diameter of the substrate 211 is preferably 0.01 μm to 50 μm from the viewpoint of preventing defects in the gas-permeable non-porous layer, and more preferably 0.1 μm to 30 μm from the viewpoint of maintaining high strength and gas permeability. The pore diameter is a pore diameter obtained by observing the surface with a scanning electron microscope (SEM) and determining the pore diameter from the observed image by the method described below. The observation magnification can be any magnification as long as the pore diameter of the object to be observed can be calculated appropriately.
(Method of determining pore size)
The images obtained by SEM observation are binarized and the pore diameter is calculated by image analysis. When calculating, the pore diameter is approximated by an ellipse, the length of the major axis of the ellipse is regarded as the pore diameter, and the average value is evaluated.

Alternatively, the pore size of the substrate 211 is defined as the average pore size obtained from pore size distribution measurement (perm porosimetry) by capillary condensation method. In perm porosimetry, the relationship between the differential pressure between atmospheric pressure and the measured pressure and the gas permeation flow rate is obtained from the gas permeation flow rate measured while gradually increasing the measured pressure of the gas applied to the sample. To obtain the pore size, a wet curve is measured on a wet sample after the sample is immersed in a wetting liquid with a known surface tension, and a dry curve is measured on a dried sample. By gradually increasing the pressure in each case within a predetermined pressure range, information on the through pore size in the sample can be obtained. The average pore size is obtained by finding the point X where the wet curve and a curve with a slope of 1/2 that of the dry curve (half dry curve) intersect, and substituting this into the equation, d = 2860 x γ / DP. In the above equation, d is the average pore size (mm), γ is the surface tension of the wetting liquid (dynes / cm), and DP is the differential pressure (Pa) between the atmospheric pressure and the gas pressure at point X. Measurements can be performed using a Perm Porometer (CFP-1500-AEC) manufactured by Porous Materials. Test conditions include, for example, a test temperature of room temperature (20°C ± 5°C), a wetting liquid of Galwick (surface tension 15.7 dynes/cm), a pressurized gas of compressed air, a sample diameter of 33 mm, a maximum supply pressure of 250 psi, and a differential pressure rise rate of 4 psi/min. When preparing a wet sample, the wetting liquid in which the sample is immersed can be placed in a desiccator and degassed to thoroughly wet the sample.

(Gas-permeable non-porous layer 212)
The gas-permeable non-porous layer 212 is a layer that has pores with a smaller pore diameter than the pores of the substrate, or has pores with an undetectable diameter and is gas permeable. The pore diameter of the gas-permeable non-porous layer 212 can be measured in the same manner as the pore diameter of the substrate 211.

The gases that permeate the gas-permeable non-porous layer 212 include oxygen, carbon dioxide, nitrogen, hydrogen, alcohols such as methanol and ethanol, organic solvents, or mixed gases thereof. From the viewpoint of effectively growing and activating microorganisms, the gas is preferably oxygen or a mixed gas containing oxygen. Gas permeability 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 resin that cures by heat or a resin that cures by exposure to ultraviolet light. It may also be a resin that cures by organic peroxide crosslinking, addition reaction crosslinking, or condensation crosslinking.

The material of the gas-permeable non-porous layer 212 may include a thermosetting polymer selected from polyolefin, polystyrene, polysulfone, polyethersulfone polytetrafluoroethylene, acrylic resin, polyurethane resin, and copolymers of these materials. In addition, a silicone-based silicone resin such as poly(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 silicone resin.

Examples of the polyurethane resin that can be used include "Asaflex 825" (manufactured by Asahi Kasei Corporation), "Pellethene 2363-80A", "Pellethene 2363-80AE", "Pellethene 2363-90A", and "Pellethene 2363-90AE" (all manufactured by The Dow Chemical Company), and "Heimullen Y-237NS" (manufactured by Dainichiseika Color & Chemicals Co., Ltd.).

The silicone resin or silicone polymer, or the silicone resin composition for obtaining them, may be blended or composed without any particular limitation. The monomer used in the silicone resin composition may be monofunctional, difunctional, trifunctional, or tetrafunctional, and may be used alone or in combination of two or more kinds. The monomer may be a halogenated alkylsilane, an unsaturated group-containing silane, an aminosilane, a mercaptosilane, or an epoxysilane. The monomer used may be, for example, a monomer represented by the following chemical formula: _HSiCl3 , _SiCl4 , _{MeSiHCl2 ,} Me3SiCl _{, MeSiCl3} , _Me2SiCl2 , Me2HSiCl, PhSiCl3 _, Ph2SiCl2 _{, MePhSiCl2 , Ph2MeSiCl} , CH2=CHSiCl3, Me(CH2=CH ₎ SiCl2, _Me2 ( _{CH2 =} CH) _SiCl , ( _{CF3CH2CH2)MeSiCl2, (CF3CH2CH2)SiCl3, CH18H37SiCl3 ( in the chemical formula , "} =" represents a double bond, "Me" represents a methyl group, _and "Ph" represents a phenyl group ₎ . The _monomers may be used alone or in combination of two or more _{kinds .} Other organic groups include alkyl groups such as propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, octyl, and decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; and aralkyl groups such as benzyl, 2-phenylethyl, and 3-phenylpropyl. Among these, methyl, phenyl, or a combination of both is preferred. This is because the components that are methyl, phenyl, or a combination of both are easy to synthesize and have good chemical stability. In addition, when using a polyorganosiloxane that has particularly good solvent resistance, it is preferable to further combine a methyl group, a phenyl group, or a combination of both with a 3,3,3-trifluoropropyl group. In addition, the silicone resin composition may contain an organoalkoxysilane. Examples of organoalkoxysilane include compounds represented by the following chemical formulas, which may be used alone or in combination of two or more. _Me3SiOCH3 , Me2Si( _OCH3 ) ₂ , MeSi _{( OCH3} ) ₃ , Si( _{OCH3 ) 4} , Me( _{C2H5 )} Si( _OCH3 ) ₂ , C2H5Si( _{OCH3 ) 3 , C10H21Si (} OCH3) ₃ , PhSi( _OCH3 ) ₃ , Ph2Si( _OCH3 ) _{2 , MeSiOC2H5 , Me2Si ( OC2H5} ) ₂ , Si _{( OC2H5} ) ₄ , _{C2H5Si ( OC2H5 ) 3} , PhSi _{(OC2H5 ) 3 , Ph2} Si( _{OC2H5 ) 2} .

Furthermore, the silicone resin composition may contain an organosilanol. Examples of the organosilanol include compounds represented by the following chemical formulas, which may be used alone or in combination of two or more: _Me3SiOH , _Me2Si (OH) ₂ , MePhSi(OH) ₂ , _{(C2H5 ) 3SiOH} , _Ph2Si (OH) ₂ , and _Ph3SiOH .

The reaction method for obtaining the silicone polymer used in the silicone resin may involve, for example, hydrolysis of chlorosilanes, ring-opening polymerization of cyclic dimethylsiloxane oligomers, etc. Examples of the polymers that can be used include dimethyl polymers, methylvinyl polymers, methylphenylvinyl polymers, and methylfluoroalkyl polymers.

The method of curing the silicone polymer, that is, the method of reacting (vulcanizing) to obtain a silicone resin, is not particularly limited. Heat vulcanization or room temperature vulcanization may be used. Either a millable type silicone resin composition or a liquid rubber type silicone resin composition may be used as the state before the reaction. A polymer having a degree of polymerization of about 4000 to 10000 is preferably used as the polymer used in the millable type silicone resin composition. In addition, it may be a one-liquid type or a two-liquid type. As the reaction method, for example, a dehydration condensation reaction between silanol groups (Si-OH), a condensation reaction between a silanol group and a hydrolyzable group, a reaction of a methylsilyl group (Si-CH ₃ ) or a vinylsilyl group (Si-CH═CH ₂ ) with an organic peroxide, an addition reaction between a vinylsilyl group and a hydrosilyl group (Si-H), a reaction with ultraviolet light, a reaction with an electron beam, etc. may be used.

(Microorganism Support Layer 213)
The microorganism support layer 213 is a layer that holds microorganisms on its surface or inside, has a space inside where microorganisms can grow, and allows organic matter in water to pass through. Examples of the material of the microorganism support layer 213 include porous sheets such as mesh, woven fabric, nonwoven fabric, foam, or microporous membrane. Examples of the material of the porous sheet include 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, fluorine resin and polyvinyl butyral resin, polyimide, polyphenylene sulfide, para- and meta-aramid, polyarylate, carbon fiber, glass fiber, aluminum fiber, steel fiber, ceramic, etc. Considering the microbial adhesion and processability, polyolefin resin, polyester resin, polyamide resin, acrylic resin, polyurethane resin, and carbon fiber are preferred.

The basis weight of the microbial 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 mass per unit area according to JIS1913:2010 General Nonwoven Fabric Test Method 6.2. By having the basis weight of the microbial support layer 213 be 2 g/m ² or more, it is possible to obtain an effect that the surface is uneven, making it easier for microorganisms to be retained in the microbial support layer 213. In addition, by having the basis weight of the microbial support layer 213 be 500 g/m ² or less, a space in which microorganisms can grow is generated inside the microbial support layer 213, making it easier to retain microorganisms, and it is possible to obtain an effect that the space makes it easier to supply oxygen to the microorganisms.

The thickness of the microorganism support layer 213 is preferably 5 μm or more and 2000 μm or less, and more preferably 20 μm or more and 500 μm or less. The thickness of the microorganism support layer 213 is a value measured according to JIS 1913:2010 General Nonwoven Fabric Test Method 6.1 Thickness Measurement Method.
The microbial support layer 213 may be formed by surface treatment of the substrate 211. In this way, the surface treatment can increase the surface roughness and membrane potential of the substrate 211, improving microbial adhesion. For example, the surface treatment may involve graft polymerization of glycidyl methacrylate and further reaction with diethylamine or sodium sulfite. Alternatively, the surface treatment may involve graft polymerization of glycidyl methacrylate and then reaction with ammonia or ethylamine.

(Gas Delivery Layer 12)
4 is a perspective view showing the gas-delivery layer 12. The gas-delivery layer 12 is a hollow plate-like member made of paper, resin, or metal. The gas-delivery layer 12 is a structure having a gas flow path S that delivers gas supplied from a first end side along a first direction. Gas from the gas delivery unit 30 (air delivery tube 31, see FIG. 1) is supplied to the lower end of the gas-delivery layer 12 via the gas delivery unit 31a. The gas-delivery layer 12 has a gas flow path S that delivers the supplied gas in the first direction (see the dashed line in FIG. 4), and releases the gas from the gas passage hole 13 on the side surface.

More specifically, as shown in FIG. 4, the gas delivery layer 12 has multiple 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 the front liner 12b and the back liner 12c, which are plate-shaped members.

The multiple core materials 12a each extend in a first direction and are arranged at a predetermined interval in a direction perpendicular to the first direction. By sandwiching the multiple core materials 12a between the front liner 12b and the rear liner 12c, multiple gas flow paths S partitioned by the core materials 12a are formed in the space between the front liner 12b and the rear liner 12c.

In addition, each core material 12a functions as a support portion that prevents the space between the front liner 12b and the back liner 12c from shrinking when pressed from the front liner 12b and back liner 12c sides. When the gas supplier 10 is immersed in wastewater W as shown in FIG. 1 or FIG. 2, the core material 12a maintains the space between the front liner 12b and the back liner 12c so that the cross-sectional area of the gas flow path S does not shrink due to water pressure. This ensures a sufficient amount of gas delivery in the gas delivery layer 12 (gas flow path S).

The front liner 12b and the back liner 12c each have a plurality of gas passage holes 13. The gas passage holes 13 are through holes formed in the front liner 12b and the back liner 12c, and the gas passage holes 13 connect the gas flow path S to the waterproof air-permeable membrane 21, so that the gas flowing through the gas flow path S is supplied to the liquid via the waterproof air-permeable membrane 21.

For example, the gas passage holes 13 are formed when the gas delivery layer 12 is molded. Alternatively, the gas passage holes 13 may be formed by processing the front liner 12b and the back liner 12c after the gas delivery layer 12 is molded. A porous sheet may be used for the front liner and the back liner. Also, if sufficient gas supply performance is obtained, a porous sheet may be used for the gas delivery layer.

The materials that make up the gas delivery layer 12 include paper, ceramic, aluminum, iron, plastics (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, phenolic resin, fluororesin, and polyvinyl butyral resin), etc.

In addition, because of their superior strength, the materials for the gas delivery layer 12 are preferably paper, aluminum, iron, polyolefin resin, polystyrene resin, PVC resin, or polyester resin.

In order to keep material costs low, it is preferable to use materials such as paper, resins such as polyolefin, polystyrene, PVC, and polyester, and metals such as aluminum as the material for the gas delivery layer 12. In addition, the material cost for the gas delivery layer 12 can be kept low by using cardboard formed so that the gas flow path S extends in the first direction (see the dashed line in FIG. 4) as the gas delivery layer 12.

The hole shapes forming the gas permeable holes of the gas delivery layer 12 can be various shapes such as circular or polygonal (including honeycomb structure). There are no particular limitations on the hole shape, but polygonal shapes are preferred, and specifically rectangular or square shapes are preferred.

(Liquid sending section 40)
The liquid delivery unit 40 has a function of discharging a fluid, which is a liquid such as water and/or a gas such as air, from the internal space of the gas supplier 10 to the outside. The liquid delivery unit 40 has a liquid delivery tube 41, a manifold 45, and a suction pump 46. The multiple liquid delivery tubes 41 are connected to the internal spaces of the multiple gas suppliers, respectively. The manifold 45 is a tube having a structure in which multiple tubes branch out from one tube. The multiple liquid delivery tubes 41 and the suction pump 46 are connected to the manifold 45. The suction pump 46 is connected to the manifold 45. The suction pump 46 can suck either a liquid or a gas, or a gas-liquid mixed fluid.

The cross-sectional shape of the liquid supply pipe 41 is not particularly limited, and may be, for example, a circle, any polygon such as a rectangle, or a combination of a part of a circle and a part of a polygon, such as a D-shaped cross section. The cross-sectional area of the inner diameter is preferably 0.1 ^mm2 or more and ¹⁰⁰ mm2 or less, more preferably ^0.5 mm2 or more and ¹⁰ mm2 or less from the viewpoint of increasing the degree of freedom of the suction pump, and even more preferably 1 ^mm2 or more and ⁴ mm2 or less from the viewpoint of generating the necessary pressure loss with a small air flow rate and obtaining a sufficient drainage flow rate.

(Occurrence of Pressure Loss, Pressure Loss Generating Section 47)
The liquid feed pipe 41 has a function of generating a pressure loss. The liquid feed pipe 41 may generate a pressure loss by having a narrow flow path throughout the entire liquid feed pipe 41, or the liquid feed pipe 41 may have a pressure loss generating portion 47 as a portion where a particularly high pressure loss occurs.

The pressure loss generating portion 47 is a portion where a flow pressure loss occurs due to the flow of gas. The pressure loss generating portion 47 can be in various forms. The pressure loss generating portion 47 can be an orifice portion 47a, 47b (FIGS. 7A, 7B) in the liquid supply pipe, a narrowed portion 47c (FIG. 7C) in the liquid supply pipe 41, a curved portion 47d (FIG. 7D) in the liquid supply pipe 41, or a portion where a communicating porous member 47e (FIG. 7E) is disposed in the liquid supply pipe 41. The orifice portions 47a, 47b are thin-walled portions with holes in the liquid supply pipe. A plate with holes may be installed inside the liquid supply pipe 41. The number of holes in the orifice portion may be one (FIG. 7A) or many (FIG. 7B).

(Operation of the liquid delivery unit)
In the wastewater treatment system 50 of this embodiment, condensed water is generated in the internal space of the gas supplier 10. If this condensed water is not removed, a part of the gas supply passage may be clogged, resulting in a decrease in gas supply efficiency.

6A and 6B show a part of the wastewater treatment system 50 of the present disclosure. That is, the gas supply bodies 10a and 10b and the liquid delivery section 40 are shown. FIG. 6A shows a state in which liquid (water) has accumulated in the internal space of the gas supply bodies 10a and 10b. The amount of water accumulated in the internal space of the gas supply bodies 10a and 10b is different as shown in FIG. 6A. In this case, the wastewater treatment system 50 of this embodiment uses the liquid delivery section 40 to drain the internal space of the gas supply bodies 10a and 10b. That is, the suction pump 46 is operated to create a negative pressure inside the manifold 45, and liquid is drained from the gas supply bodies 10a and 10b.

In this way, when the liquid is continuously discharged by the liquid delivery unit 40, as shown in FIG. 6B, all liquid (water) is discharged from the gas supply body 10b, which initially had a small amount of accumulated water. In this state, gas is discharged from the internal space of the gas supply body 10a, and the flow of the gas (faster than the discharge of the liquid) generates a flow pressure loss. This pressure loss maintains the negative pressure in the manifold 45, and liquid continues to be discharged from the gas supply body 10b, where liquid remains. Note that the capacity of the suction pump 46 and the structure of the liquid delivery unit 40 (adjustment of the generated pressure loss) are adjusted in advance at the design stage so that a negative pressure equal to or greater than the head pressure difference of the liquid is generated.

In this embodiment, the amount of gas supplied to the internal space of the gas supplier 10 by the air supply pipe 31 is preferably greater than the amount of gas exhausted by the liquid supply pipe 41. In this case, even when the suction pump 46 is operating, the pressure in the internal space of the gas supplier 10 is approximately atmospheric pressure. In addition, the wastewater treatment system 50 has a mechanism for preventing the pressure in the internal space of the gas supplier 10 from fluctuating significantly from atmospheric pressure. In this embodiment, the wastewater treatment system 50 preferably has a mechanism for exhausting the internal space of the gas supplier 10 (including exhausting from the opening 21b) in addition to the liquid supply pipe 41.

In the case where there are three or more gas supplies 10, the liquid is discharged in the same manner starting from the gas supply 10 that initially contained the smallest amount of accumulated water, until the entire water has been discharged.
In the wastewater treatment system 50 of the present embodiment, the pressure in the manifold 45 drops precisely because of the pressure loss generating unit 47. Without the pressure loss generating unit 47, in the state of Fig. 6B, air would be preferentially sucked from the gas supplier 10b from which the discharge of liquid has been completed, the negative pressure in the manifold 45 would not be maintained, and liquid would not be able to be discharged from the gas supplier 10a from which liquid remains. In the present disclosure, by generating a pressure loss, even after the discharge of liquid from the gas supplier 10b has been completed, liquid can continue to be discharged from other gas suppliers 10a.

Second Embodiment
As shown in FIG. 8, the wastewater treatment system 50a of this embodiment is provided with an air supply unit 30a and a liquid supply unit 40a. The rest is the same as the wastewater treatment system 50 of the first embodiment. That is, when air (oxygen) is supplied to the internal space of the gas supplier, the blower 36 is used to supply air. Conversely, when the fluid in the internal space of the gas supplier 10 is discharged, the suction pump 46 is operated to discharge the fluid. That is, each of these is performed intermittently. Also, in this case, as in the first embodiment, the wastewater treatment system 50a preferably has a mechanism for preventing the pressure in the internal space of the gas supplier 10 from fluctuating significantly from the atmospheric pressure.

Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the present disclosure as set forth in the claims.

10 Gas supplier 12 Gas supply layer 21 Waterproof air-permeable membrane 30, 30a Air supply section 31 Air supply pipe 35 Manifold (of air supply section) 36 Air supply pump 40, 40a Liquid supply section 41 Liquid supply pipe 45 Manifold (of liquid supply section) 46 Suction pump 50, 50a Wastewater treatment system 51 Wastewater treatment tank 52 Supplier unit 100, 100a Wastewater treatment device

Claims (8)

A wastewater treatment system that purifies wastewater using the action of microorganisms,
A gas supply body used by immersing in the wastewater, the gas supply body including a waterproof air-permeable membrane, and the gas supplied to an internal space partitioned by the waterproof air-permeable membrane is supplied to the microorganisms in the wastewater outside the waterproof air-permeable membrane; and
A liquid delivery unit that discharges fluid from the internal spaces of the plurality of gas supply bodies;
Equipped with
The liquid delivery unit includes:
A plurality of liquid supply pipes respectively connected to the internal spaces of the plurality of gas supply bodies;
a manifold connected to the plurality of liquid delivery pipes;
a suction pump connected to the manifold;
When the suction pump discharges the fluid in the internal space of the gas supply body to the outside, the liquid in the internal space is discharged to the outside by utilizing a negative pressure generated by a flow pressure loss of the gas.
Wastewater treatment systems. The internal cross-sectional area of the liquid delivery tube is ¹⁰ mm2 or less.
2. The wastewater treatment system of claim 1. The liquid supply pipe is provided with a pressure loss generating section that generates a flow pressure loss of a gas.
3. The wastewater treatment system according to claim 1 or 2. the pressure loss generating portion is an orifice portion in the liquid feed pipe, a narrowed portion in the liquid feed pipe, a curved portion in the liquid feed pipe, or a portion in the liquid feed pipe where a communicating porous member is disposed.
4. The wastewater treatment system of claim 3 . Further comprising an air supply unit that supplies gas to the internal space of the gas supply body.
The wastewater treatment system according to any one of claims 1 to 4. The gas supply unit includes an air supply pipe connected to an internal space of the gas supplier,
The air supply pipe is provided separately from the liquid supply pipe.
The wastewater treatment system of claim 5. The gas supply unit includes an air supply pipe connected to an internal space of the gas supplier,
The air supply pipe is common to the liquid supply pipe.
The wastewater treatment system of claim 5. A wastewater treatment method for purifying wastewater by utilizing the action of microorganisms using a wastewater treatment device, comprising the steps of:
The wastewater treatment device comprises:
A gas supply body used by immersing in the wastewater, the gas supply body including a waterproof air-permeable membrane, and the gas supplied to an internal space partitioned by the waterproof air-permeable membrane is supplied to the microorganisms in the wastewater outside the waterproof air-permeable membrane; and
A liquid delivery unit that discharges fluid from the internal spaces of the plurality of gas supply bodies;
Equipped with
The liquid delivery unit includes:
A plurality of liquid supply pipes respectively connected to the internal spaces of the plurality of gas supply bodies;
a manifold connected to the plurality of liquid delivery pipes;
a suction pump connected to the manifold;
When the suction pump discharges the fluid in the internal space of the gas supply body to the outside, the liquid in the internal space is discharged to the outside by utilizing a negative pressure generated by a flow pressure loss of the gas.
Wastewater treatment methods.

Images