WO2023187933A1

WO2023187933A1 - Sewage purification apparatus

Info

Publication number: WO2023187933A1
Application number: PCT/JP2022/015184
Authority: WO
Inventors: 敏治柳川
Original assignee: 中国電力株式会社
Priority date: 2022-03-28
Filing date: 2022-03-28
Publication date: 2023-10-05
Also published as: JPWO2023187933A1; JP7298784B1

Abstract

The purpose of the present invention is to provide a sewage purification apparatus which makes it possible to remove ammonia easily.　Provided is a sewage purification apparatus provided with a contact filtration tank for purifying sewage and an electrolysis tank, in which the electrolysis tank is arranged upstream of the contact filtration tank, the contact filtration tank includes oyster shells, the electrolysis tank is provided with an electrolysis unit, the sewage in the electrolysis tank contains sodium chloride and water, and the electrolysis unit electrolyzes the sewage in the electrolysis tank to produce sodium hypochlorite.

Description

Sewage purification equipment

The present invention relates to a sewage purification device.

Patent Document 1 describes a purification device that uses oyster shells to purify wastewater containing sludge components in stages. However, there is a problem in that ammonia is not easy to remove. Furthermore, if ammonia is removed only by microorganisms, there is a problem in that the device becomes large.

Japanese Patent Application Publication No. 2008-720

An object of the present invention is to provide a sewage purification device that can easily remove ammonia.

(1) The present invention includes a contact filtration tank for purifying wastewater and an electrolysis tank, the electrolysis tank is disposed upstream of the contact filtration tank, and the contact filtration tank has oyster shells. The electrolysis tank includes an electrolysis section, the wastewater in the electrolysis tank contains sodium chloride and water, and the electrolysis section electrolyzes the wastewater in the electrolysis tank. This invention relates to a sewage purification device that generates sodium hypochlorite by decomposition.

(2) The wastewater in the electrolysis tank contains ammonia, and at least a portion of the ammonia reacts with the sodium hypochlorite produced by the electrolysis to produce nitrogen. The sewage purification device described in 1).

(3) At least one tank of the electrolytic tank and a tank disposed upstream of the electrolytic tank is equipped with a chlorine concentration measuring section, and the chlorine concentration measuring section is equipped with a chlorine concentration measuring section. The sewage purification device according to (1) or (2), wherein the chlorine concentration of the sewage in the tank is measured.

(4) At least one of the tanks disposed downstream of the electrolytic tank includes a chlorine concentration measuring section, and the chlorine concentration measuring section is located in the tank provided with the chlorine concentration measuring section. The sewage purification device according to any one of (1) to (3), which measures the chlorine concentration of sewage.

(5) The sewage purification device according to any one of (1) to (4), wherein the sewage contains E. coli, and the E. coli is sterilized by the sodium hypochlorite generated by the electrolysis. .

(6) Any one of (1) to (5), wherein the electrolysis section includes a first electrode and a second electrode, and the first electrode and the second electrode are capable of reversing their polarities. The sewage purification device described in .

According to the present invention, it is possible to provide a sewage purification device that easily removes ammonia.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the whole structure of the water utilization system in which the sewage purification apparatus of this invention is used, and the schematic structure of the sewage purification apparatus of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the schematic structure of the sewage purification apparatus of this invention. It is a sectional view showing the schematic structure of the 1st contact filtration tank of the present invention. It is a top view showing the schematic structure of the 1st contact filtration tank of the present invention. FIG. 3 is a diagram showing a mesh filter medium of the present invention. It is a figure showing the honeycomb filter medium of the present invention.

≪First embodiment≫
Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in each drawing.

<Water reuse system>
As shown in FIG. 1, the sewage purification device 1 of the present invention constitutes a part of a water reuse system 100.
The water reuse system 100 includes a sewage purification device 1 and water usage equipment 2. The sewage purification device 1 and the water utilization equipment 2 are connected via piping 5, thereby forming a closed water system as a whole. That is, in the water reuse system 100, water circulates between the sewage purification device 1 and the water usage equipment 2, and as a general rule, water is not released to the outside. This water circulation is realized by the sewage purification device 1 purifying the sewage discharged by the water usage equipment 2, and the water usage equipment 2 reusing the purified water.
Note that purified water is sometimes referred to as purified water. In addition, water may be used to include sewage and purified water.

<Water usage equipment>
The water utilization facility 2 is a facility that utilizes water and discharges sewage generated by the use of water. Examples of the water usage equipment 2 include toilets, factory cleaning equipment, and aquaculture tanks.

<Sewage purification equipment>
The sewage purification device 1 is a device that purifies sewage discharged from the water usage equipment 2 and supplies the purified water to the water usage equipment 2.
As shown in FIG. 1, purification of wastewater by the wastewater purification device 1 can be divided into three processes: primary treatment T1, secondary treatment T2, and tertiary treatment T3.

<Overview of primary processing>
The main content of the primary treatment T1 is to separate wastewater into solid and liquid.
In the primary treatment T1, in addition to this separation, organic matter is decomposed by anaerobic microorganisms.
In the primary treatment T1, aeration is not performed in order to efficiently perform solid-liquid separation of wastewater. Therefore, it is preferable to use anaerobic microorganisms rather than aerobic microorganisms for decomposing organic matter.

<Summary of secondary processing>
The main content of the secondary treatment T2 is to purify the liquid part of the wastewater separated in the primary treatment using aerobic microorganisms. In the secondary treatment T2, aeration is performed to promote the decomposition of organic matter by aerobic microorganisms.

<Overview of tertiary processing>
The main content of the tertiary treatment T3 is to further purify the wastewater purified in the secondary treatment T2. In the tertiary treatment T3, wastewater is purified using oyster shells. At this time, aeration is performed to promote the decomposition of organic matter by aerobic microorganisms.
Furthermore, in the tertiary treatment T3, disinfection, decolorization, and deodorization of wastewater are also performed.
Further, from the primary treatment T1 to the tertiary treatment T3, pH adjustment, ammonia nitrification, and denitrification are performed.

<Tank configuration of sewage purification equipment>
The tank configuration of the sewage purification device 1 will be explained based on FIGS. 1 and 2. The arrows in Figure 1 indicate the flow of water. Further, in FIG. 2, piping between the tanks may be omitted.
The sewage purification device 1 includes, from upstream, a precipitation separation tank 10, a contact oxidation tank 20, a first settling tank 22, a first contact filtration tank 30, a second contact filtration tank 32, a second settling tank 34, and a storage tank 36. .
The sedimentation separation tank 10 is responsible for primary treatment T1. The contact oxidation tank 20 and the first precipitation tank 22 are responsible for the secondary treatment T2. The first contact filtration tank 30, the second contact filtration tank 32, the second settling tank 34, and the storage tank 36 are responsible for the tertiary treatment T3.

The wastewater discharged from the water utilization equipment 2 flows into the sedimentation separation tank 10. The inflowing sewage passes through each tank of the sewage purification device 1 and is purified. The purified wastewater flows from the second settling tank 34 into the storage tank 36 as purified water. The inflowing purified water is supplied to the water utilization equipment 2 from the storage tank 36.

The sewage purification device 1 of Embodiment 1 has features in the contact oxidation tank 20 and the first contact filtration tank 30. Specifically, the contact oxidation tank 20 is equipped with an electrolysis section 50 and a chlorine concentration measurement section 52. Further, the first contact filtration tank 30 is equipped with a honeycomb filter medium 76. Hereinafter, each tank will be explained in order from the upstream.

<Sedimentation separation tank>
In the sedimentation separation tank 10, wastewater flowing from the water utilization equipment 2 is separated into solid and liquid by sedimentation.
Solid matter, floating matter, etc. contained in the wastewater are precipitated and taken out as precipitate 90. Only liquid flows into the contact oxidation tank 20. Further, in the sedimentation separation tank 10, decomposition of organic matter by anaerobic microorganisms is also performed.

<Contact oxidation tank>
In the contact oxidation tank 20, organic matter contained in the liquid separated into solid and liquid in the precipitation separation tank 10 is decomposed by aerobic microorganisms.
A contact material made of resin is placed in the contact oxidation tank 20 . Aerobic microorganisms are attached to the surface of the contact material. Aeration is also performed to promote the decomposition of organic matter by aerobic microorganisms.

<Electrolysis section>
In the sewage purification device 1 of the first embodiment, the contact oxidation tank 20 is equipped with an electrolysis section 50. The contact oxidation tank 20 is also called an electrolysis tank. The electrolysis section 50 is a part that electrolyzes wastewater in the tank. The electrolysis unit 50 electrolyzes sodium chloride and water contained in the wastewater in the contact oxidation tank 20 to generate sodium hypochlorite.
The reaction formula for this electrolysis is as follows.
NaCl+ _H2O →NaClO+ _H2

<Sodium hypochlorite>
Sodium hypochlorite generated by electrolysis in the electrolysis unit 50 reacts with ammonia contained in the wastewater in the contact oxidation tank 20 .
The reaction formula between ammonia and sodium hypochlorite is as follows.
2NH ₃ +3NaOCl→N ₂ ↑+3NaCl+3H ₂ O
This reaction allows ammonia to be removed from the wastewater in the tank.
Also, the generated nitrogen gas is released into the atmosphere. Thereby, ammonia nitrogen contained in the wastewater can be removed from the wastewater.

<Effects in contact oxidation tank>
Ammonia is a highly toxic substance to microorganisms. By removing ammonia from wastewater, aerobic microorganisms within the contact oxidation tank 20 can be protected.
Furthermore, by removing ammonia from the wastewater, it is possible to suppress an increase in the pH of the wastewater in the contact oxidation tank 20 caused by ammonia.
Furthermore, there is no need to add sodium hypochlorite from outside the tank. Alternatively, the opportunity for its input can be reduced. Therefore, maintenance and management of the sewage purification device 1 can be simplified.
Also, sodium hypochlorite may reduce the activity of microorganisms. Therefore, it is preferable that the wastewater does not contain excessive sodium hypochlorite. In the sewage purification device 1 of Embodiment 1, sodium hypochlorite is produced by electrolysis. Therefore, it is easier to adjust the amount of sodium hypochlorite contained in wastewater than when sodium hypochlorite is added from outside the tank. Therefore, it becomes easy to suppress the activity of microorganisms from decreasing.
Furthermore, when ammonia is removed using microorganisms, for example when ammonia is nitrified using nitrifying bacteria, the processing tank often becomes large. On the other hand, when ammonia is removed using sodium hypochlorite produced by electrolysis, it becomes easy to downsize the treatment tank.

<Overall effects of sewage purification equipment>
Among the tanks of the sewage purification device 1, the contact oxidation tank 20 often has a high ammonia concentration in the sewage in the tank. Therefore, by arranging the electrolysis unit 50 in the contact oxidation tank 20, ammonia can be efficiently removed in the sewage purification apparatus 1 as a whole.
Furthermore, the need for ammonia removal by nitrification can be reduced. Therefore, it is possible to prevent the pH of wastewater from dropping too much due to nitrification. Thereby, the burden on the oyster shells provided downstream of the contact oxidation tank 20 can be reduced. This is because the need for neutralizing wastewater with oyster shells is reduced.

<Electrode of electrolysis section>
The electrolysis unit 50 includes a first electrode and a second electrode (not shown). The first electrode and the second electrode are immersed in waste water in the catalytic oxidation tank 20 for electrolysis.
The polarity of the first electrode and the polarity of the second electrode can be reversed. When electrolysis is performed, solid substances such as calcium may adhere to the electrode. For example, by periodically reversing the polarity of the first electrode and the polarity of the second electrode, it is possible to suppress the adhesion of solid objects to the electrodes or to remove the solid objects adhering to the electrodes. Become.

<Chlorine concentration measuring section>
In the sewage purification device 1 of the first embodiment, the contact oxidation tank 20 is equipped with a chlorine concentration measuring section 52.
The chlorine concentration measuring section 52 is a section that measures the chlorine concentration of wastewater in the tank. The chlorine concentration measuring section 52 measures the chlorine concentration of the wastewater in the contact oxidation tank 20.
Sodium hypochlorite may have an adverse effect on the activity of microorganisms such as aerobic microorganisms, anaerobic microorganisms, and nitrifying bacteria. Therefore, it is preferable to adjust the above-mentioned electrolysis so that it does not become excessive. Specifically, the electrolysis is preferably controlled so as not to generate an excessive amount of sodium hypochlorite relative to the amount of ammonia contained in the wastewater.

<Effects of the chlorine concentration measuring section>
Regarding this, the sewage purification device 1 of the first embodiment is equipped with a chlorine concentration measuring section 52. Chlorine concentration is an indicator of the amount of sodium hypochlorite in solution.
In the sewage purification device 1, the time and intensity of electrolysis by the electrolysis section 50 can be adjusted based on the chlorine concentration measured by the chlorine concentration measurement section 52. Thereby, generation of excessive sodium hypochlorite can be suppressed.

<Arrangement of chlorine concentration measuring section>
The chlorine concentration measurement unit 52 can be provided in the contact oxidation tank 20 at a position where wastewater flows from the precipitation separation tank 10. Thereby, it is possible to quickly determine whether or not it is necessary to generate sodium hypochlorite by electrolysis for the inflowing wastewater, and the appropriate amount of generation.
However, the position where the chlorine concentration measuring section 52 is provided is not particularly limited. For example, the chlorine concentration measuring section 52 may be provided at a position close to the contact material to which aerobic microorganisms have adhered. This makes it possible to evaluate the chlorine concentration of wastewater in which the decomposition of organic matter by aerobic microorganisms has progressed, as well as the content of sodium hypochlorite. This makes it possible to adjust electrolysis in accordance with the actual situation of the wastewater in the contact oxidation tank 20.
Additionally, since the chlorine concentration is measured at a location close to aerobic microorganisms, it is possible to adjust electrolysis while taking into account the effects of sodium hypochlorite on aerobic microorganisms.

<Placement in a tank other than the contact oxidation tank>
The electrolysis section 50 can also be provided in a tank other than the catalytic oxidation tank 20. Moreover, two or more electrolyzers 50 can also be provided in the sewage purification apparatus 1.

The chlorine concentration measuring section 52 can also be provided in a tank other than the contact oxidation tank 20. For example, it can be provided in a settling tank or a contact filtration tank downstream of the contact oxidation tank 20. Thereby, each tank can be kept clean with sodium hypochlorite while suppressing the adverse effects of sodium hypochlorite on microorganisms.
Specifically, each tank is sterilized with sodium hypochlorite while confirming by measurement by the chlorine concentration measurement unit 52 that the amount of sodium hypochlorite is within a range where no adverse effect on microorganisms is a problem. It can be performed.
Moreover, sterilization of wastewater can be performed using sodium hypochlorite without using the disinfection section 40. This will be discussed later.

Furthermore, the control of the electrolyzer 50 is not limited to feedback control based on the measurement results of the chlorine concentration measuring section 52, as described above.
For example, if the water usage equipment 2 is a facility such as a toilet where the amount of sewage discharged can be predicted depending on the number of users, the electrolysis unit 50 performs electricity production according to the number of users. The amount of degradation can be controlled.

<First settling tank>
In the first sedimentation tank 22, the wastewater purified by aerobic microorganisms in the contact oxidation tank 20 is separated into a supernatant liquid and a precipitate.
The separated supernatant liquid flows into the first contact filtration tank 30.

<First contact filtration tank>
In the first contact filtration tank 30, the supernatant liquid separated in the first settling tank 22 is treated using microorganisms.
In the first contact filtration tank 30, a contact material to which nitrifying bacteria as microorganisms is attached is arranged. In the sewage purification device 1 of the first embodiment, a honeycomb filter medium 76 is provided as this contact material.

<Internal configuration of the first contact filtration tank>
The internal configuration of the first contact filtration tank 30 will be described with reference to FIGS. 3 to 6.
As shown in FIG. 3, the first contact filtration tank 30 includes a first porous tube 70, a sheet filter 72, a plastic filter medium 74, a honeycomb filter medium 76, a grating 78, a second porous tube 80, A block 82 is provided.
These are, from the top 302 to the bottom 301 of the first contact filtration tank 30, a first porous pipe 70, a sheet filter 72, a plastic filter medium 74, a honeycomb filter medium 76, a grating 78, a second porous pipe 80, and a block 82. They are arranged in order.
In addition, in the following description, the side of the upper part 302 may be called the upper side, and the side of the bottom part 301 may be called the lower side.

<First porous pipe>
The first porous pipe 70 is a pipe that supplies the supernatant liquid separated in the first settling tank 22 into the first contact filtration tank 30.
The first porous tube 70 has a tube shape. The first porous pipe 70 can be made of metal, resin, or the like, for example.
The first porous tube 70 has a plurality of holes 701 on the circumferential surface of the tube. The holes 701 are arranged so as to form a plurality of rows along the longitudinal direction of the first porous pipe 70. Further, this hole 701 opens in the direction of the sheet-like filter 72, that is, in the direction of the bottom 301 of the first contact filtration tank 30.
The supernatant liquid separated in the first settling tank 22 is discharged from the holes 701 to the sheet filter 72 while flowing in the direction of the arrow in FIG.
As shown in FIG. 4, the first porous pipe 70 extends from one end to the other end in the length direction of the first contact filtration tank 30. That is, the first porous pipe 70 extends substantially horizontally.
Further, three first porous pipes 70 are provided in the first contact filtration tank 30. These three first porous tubes 70 are arranged at approximately equal intervals in the width direction.
The supernatant liquid from the first settling tank 22 is dispersed and discharged from the plurality of holes 701 of each of the three first porous pipes 70 . Thereby, the supernatant liquid from the first settling tank 22 is supplied to the entire sheet-like filter 72 .
In addition, in FIG. 4, description of the sheet-like filter 72 and the plastic filter medium 74 is omitted for convenience of explanation.

<Sheet filter>
The sheet filter 72 is a filter that removes suspended solids of a specific size from wastewater.
The sheet-like filter 72 of Embodiment 1 removes suspended matter having a diameter of about 10 μm or more and less than about 80 μm.
The sheet-like filter 72 can be formed from fibrous resin or the like. Further, the sheet-like filter 72 has a mesh having a size of about 10 μm.
The sheet filter 72 is arranged below the first porous tube 70 . Further, the sheet-like filter 72 extends over almost the entire surface of the first contact filtration tank 30 in plan view. Thereby, the sheet-like filter 72 covers almost the entire surface of the plastic filter medium 74 disposed below it.
Note that a plan view refers to viewing the first contact filtration tank 30 from the top 302 toward the bottom 301.

<Plastic filter media>
The plastic filter medium 74 is a filter medium that spreads the supplied wastewater in a predetermined direction.
The plastic filter medium 74 of the first embodiment spreads the wastewater supplied from the sheet filter 72 in a direction parallel to the bottom 301 of the first contact filtration tank 30.
The plastic filter medium 74 has a rectangular parallelepiped shape, which is integrally formed by stacking a plurality of mesh filter mediums 741 of about 6 cm square shown in FIG. The wastewater supplied to the plastic filter medium 74 spreads in the plane direction of the mesh filter medium 741.

Nitrifying bacteria that nitrify ammonia are attached to the surface of the plastic filter medium 74. Note that nitrifying bacteria have the property of adhering to solid carriers. Therefore, for example, by immersing the plastic filter medium 74 in a sewage tank where nitrifying bacteria exist, the nitrifying bacteria can be attached to the surface of the plastic filter medium 74.

A plurality of plastic filter media 74 are arranged below the sheet filter 72 and above the honeycomb filter media 76. The plastic filter media 74 arranged side by side are oriented such that the longitudinal direction of the rectangular parallelepiped shape is parallel to the bottom 301 of the first contact filtration tank 30 .
With the above arrangement, the waste water from the sheet filter 72 that has come into contact with the surface of the plastic filter media 74 flows toward the honeycomb filter media 76 while being transmitted between adjacent plastic filter media 74 . That is, the wastewater that has passed through the plastic filter medium 74 is discharged toward the honeycomb filter medium 76 while being dispersed in a direction parallel to the bottom 301 of the first contact filtration tank 30 .
Thereby, the plastic filter medium 74 nitrifies the waste water from the sheet filter 72 and supplies the waste water almost evenly to the entire honeycomb filter medium 76 .

<Honeycomb filter medium 76>
The honeycomb filter medium 76 is a filter medium including a plurality of hollow tubes each having a hexagonal cross section.
As shown in FIG. 6, the honeycomb filter medium 76 of Embodiment 1 has a plurality of hollow tubes 761.

The hollow tube 761 has a hollow hexagonal column shape. The distance between opposing vertices in the hexagonal cross section of the hollow tube 761 is shown by arrow A in FIG. This distance may be approximately 13 mm, for example. Further, the hollow tube 761 can be made of resin, for example.
The honeycomb filter medium 76 is formed by integrally forming a plurality of hollow tubes 761 so as to share an outer surface with each other. In other words, in the honeycomb filter medium 76, the hollow tubes 761 are arranged and fixed so that their outer surfaces are in contact with each other without any gaps.
The honeycomb filter medium 76 is arranged in the first contact filtration tank 30 so that the openings at both ends of the hollow tubes 761 that constitute the honeycomb filter medium 76 face the top 302 and bottom 301 of the first contact filtration tank 30, respectively. There is. That is, the hollow tube 761 extends substantially vertically.

The honeycomb filter medium 76 has elasticity against forces applied from both ends in the width direction or length direction shown in FIG. 4 . Therefore, the honeycomb filter medium 76 can be fixed to the first contact filtration tank 30, for example, as follows.
First, a force that resists the elastic force is applied to bring the honeycomb filter medium 76 into a contracted state. Then, the honeycomb filter medium 76 is placed in the first contact filtration tank 30 in the contracted state. Next, by releasing the force that resists the elastic force, the outer surface of the honeycomb filter medium 76 is pressed against the inner wall of the first contact filtration tank 30. Thereby, the honeycomb filter medium 76 is fixed in the middle part of the first contact filtration tank 30 without any gaps.
In addition, although the 1st contact filtration tank 30 is formed of resin, it has a larger specific gravity than sewage.

By arranging the honeycomb filter medium 76 in the first contact filtration tank 30 as described above, the honeycomb filter medium 76 is firmly secured so that it will not move within the first contact filtration tank 30 due to the flow of wastewater, etc. is fixed in the first contact filtration tank 30.
Note that the honeycomb filter medium 76 can also be fixed to the first contact filtration tank 30 by a method other than the above-mentioned method. For example, the honeycomb filter medium 76 can be fixed to the first contact filtration tank 30 with an adhesive.

<Nitrifying bacteria>
Nitrifying bacteria are attached to the inner surface of the hollow tube 761. The nitrifying bacteria may originate from the plastic filter media 74.
That is, when wastewater is supplied to the hollow tube 761 from the plastic filter medium 74 to which nitrifying bacteria have adhered, the nitrifying bacteria move to the hollow tube 761 along with the wastewater. The nitrifying bacteria adhere to the inner surface of the hollow tube 761. The attached nitrifying bacteria proliferate on the inner surface of the hollow tube 761.
As described above, nitrifying bacteria can be attached to the inner surface of the hollow tube 761 without any special work for attaching the nitrifying bacteria to the inner surface of the hollow tube 761.

<Nitrification using honeycomb filter media>
Sewage is supplied to the honeycomb filter medium 76 almost evenly from the plastic filter medium 74 to the entire honeycomb filter medium 76 . Therefore, the wastewater flows from the upper side of the honeycomb filter medium 76 to the lower side through many hollow pipes 761. Therefore, the dirty water comes into contact with the inner surfaces of many hollow tubes 761. Thereby, ammonia in wastewater is efficiently nitrified. That is, ammonia nitrogen can be efficiently converted into nitrate nitrogen. Thereby, highly toxic and harmful ammonia can be easily removed.
Note that the cross-sectional shape of the hollow tube 761 is not limited to a hexagonal shape, and may be, for example, a quadrangular shape.

<Second porous pipe>
The second porous pipe 80 is a pipe that supplies air to the honeycomb filter medium 76.
The second porous tube 80 has a tube shape. The second porous pipe 80 can be made of metal, resin, or the like, for example.
The second porous pipe 80 has a plurality of holes 801 on its circumferential surface. The holes 801 are arranged so as to form a plurality of rows along the longitudinal direction of the second porous pipe 80. Moreover, this hole 801 opens in the direction of the honeycomb filter medium 76, that is, in the direction of the upper part 302 of the first contact filtration tank 30.

The second porous pipe 80 is disposed below the honeycomb filter medium 76. Furthermore, as shown in FIG. It extends to the end. That is, the second porous pipe 80 extends substantially horizontally. Further, three second porous pipes 80 are provided in the first contact filtration tank 30. These three second porous tubes 80 are arranged at approximately equal intervals in the width direction.

Air is fed into the second porous pipe 80 from one end thereof by a blower or the like (not shown). This air is discharged from the hole 801, becomes a bubble 802, and reaches the inside of the hollow tube 761 from the lower side of the hollow tube 761.
The air bubbles 802 can suppress the flow of wastewater from the upper side to the lower side within the hollow pipe 761. Furthermore, it is possible to generate a flow of wastewater from the lower side to the upper side within the hollow pipe 761.
Furthermore, within the same hollow tube 761 or in adjacent hollow tubes 761, the above-described flow from the upper side to the lower side and the flow from the lower side to the upper side can be generated alternately and repeatedly. .

As described above, in the sewage purification device 1 of the first embodiment, a flow of sewage in a direction from the bottom 301 to the top 302 is generated in a part of the hollow pipe 761 by discharging gas from the hole 801, and , another part of the hollow tube 761 can generate a flow of waste water in the opposite direction from the top 302 to the bottom 301 .
Thereby, the contact time and number of contacts between the inner surface of the hollow tube 761 and the waste water can be increased. Thereby, ammonia can be efficiently nitrified.
Furthermore, it is possible to prevent the inside of the hollow tube 761 from being blocked.

Further, when the above-mentioned gas is air, oxygen can be supplied to the inside of the hollow tube 761 by the bubbles 802. Thereby, the amount of dissolved oxygen in the wastewater in the hollow pipe 761 can be increased. This makes it possible to maintain an aerobic environment for the nitrifying bacteria, so that ammonia can be efficiently nitrified.

Note that the gas sent into the second porous tube 80 is not limited to air, and may be other gas such as nitrogen.
Moreover, the gas supply from the second porous pipe 80 may be performed continuously or intermittently. Further, the second porous tube 80 may supply gas to only some of the plurality of hollow tubes 761 .

<Block>
The block 82 is a member that is arranged at the bottom 301 of the first contact filtration tank 30 and serves as the base of the grating 78.
The block 82 has a rectangular parallelepiped shape and is made of a material having a higher specific gravity than sewage, such as resin or concrete.
A total of four blocks 82 are arranged, one each near the four corners of the bottom 301 of the first contact filtration tank 30.

<Grating>
The grating 78 is a hard plate material having a lattice shape.
The grating 78 can be made of a material having a higher specific gravity than the waste water, such as resin.
Grating 78 is placed over block 82 . A honeycomb filter medium 76 is arranged on the grating 78. That is, the grating 78 supports the honeycomb filter medium 76 from below.
On the other hand, the second porous pipe 80 is arranged below the grating 78, that is, between the grating 78 and the bottom 301 of the first contact filtration tank 30.
In other words, the honeycomb filter medium 76 is arranged above the second porous tube 80 by the block 82 and the grating 78. Thereby, the air discharged from the second porous tube 80 is supplied to the honeycomb filter medium 76. At this time, the air discharged from the second porous tube 80 passes between the gratings of the grating 78.

<Effects of honeycomb filter media>
The sewage purification device 1 of the first embodiment includes a honeycomb filter medium 76 to which nitrifying bacteria are attached. Therefore, ammonia can be reliably nitrified and the amount of ammonia in wastewater can be reduced.
Here, a second contact filtration tank 32 is arranged downstream of the first contact filtration tank 30. This second contact filtration tank 32 is equipped with oyster shells. Many microorganisms are attached to oyster shells. Furthermore, ammonia is highly toxic to microorganisms.
In the sewage cleaning device 1 of the first embodiment, ammonia can be removed in the tank immediately before the second contact filtration tank 32, as described above. Therefore, oyster shells and microorganisms in the second contact filtration tank 32 can be protected from the toxicity of ammonia. Therefore, the amount of oyster shells used and the frequency of replacing oyster shells can be reduced.

Due to the action of the electrolysis unit 50 provided in the contact oxidation tank 20 described above, even if ammonia is removed in the contact oxidation tank 20, remaining ammonia and subsequent tanks, for example, the Ammonia generated in the first precipitation tank 22 due to the action of microorganisms, etc. can be removed in the first contact filtration tank 30.

<Other microorganisms>
Note that the microorganisms to be attached to the honeycomb filter medium 76 are not limited to nitrifying bacteria. For example, in addition to nitrifying bacteria, aerobic microorganisms that decompose organic matter can also be attached to the honeycomb filter medium 76.
In this case, aerobic microorganisms that decompose organic matter can promote purification of wastewater. Moreover, thereby, the burden of oyster shells on the second contact filtration tank can be reduced.

<Second contact filtration tank>
In the second contact filtration tank 32, wastewater is filtered using oyster shells.
Oyster shells are placed in the second contact filtration tank 32 as a contact material. Aeration is also performed to facilitate filtration through the oyster shells.
If the removal of ammonia from wastewater and the decomposition of organic matter are progressing in the tanks up to the second contact filtration tank 32, the oyster shells in the second contact filtration tank 32 will mainly absorb pH due to neutralization. It only serves a regulatory function. In this case, the rate of deterioration of oyster shells can be slowed down.
This makes it possible to reduce the amount of oyster shells used and to slow down the frequency of replacing oyster shells.

In the sewage purification device 1 of Embodiment 1, it is possible to achieve both the treatment of ammonia by microorganisms in the first contact filtration tank 30 and the pH stabilization effect by oyster shells in the second contact filtration tank 32 at a high level. I can do it. This makes it easy to downsize the entire sewage purification device 1.

<Second settling tank>
In the second sedimentation tank 34, the wastewater filtered in the second contact filtration tank 32 is separated into a supernatant liquid and a precipitate. The separated supernatant liquid flows into the storage tank 36.

<Disinfection Department>
The disinfection section 40 is a section that supplies a sterilizing substance for disinfection to the water flowing out from the second settling tank 34 and before flowing into the storage tank 36 .
The water flowing out of the second settling tank 34 may require disinfection by sterilization. In that case, the sterilizing substance supplied by the sterilizing section 40 sterilizes bacteria contained in the water flowing out from the second settling tank 34 . Examples of bacteria to be sterilized include Salmonella typhi, Escherichia coli, Staphylococcus, and Salmonella.
Further, as the sterilizing substance, for example, a chlorine-based substance such as solid chlorine can be used.
Note that the supply of the sterilizing substance to the water flowing out from the second settling tank 34 can be performed manually, not by the disinfection unit 40.

<Storage tank>
The supernatant liquid from the second settling tank 34 flows into the storage tank 36 . The water is then stored as purified water for reuse.
Furthermore, the storage tank 36 is equipped with activated carbon 62. The activated carbon 62 deodorizes and decolorizes the purified water stored in the storage tank 36.
The purified water stored in the storage tank 36 is supplied to the water usage equipment 2, for example, a toilet, and is reused as flushing water for the toilet.

<Surplus water storage tank>
The surplus purified water in the storage tank 36 flows into the surplus water storage tank 38 from the storage tank 36 . The inflow purified water is then stored so as not to flow out of the water reuse system 100.
This allows recycling and reuse of wastewater within a closed system.

<Purification and disinfection with sodium hypochlorite>
In the sewage purification device 1 of the first embodiment, sodium hypochlorite generated by the electrolysis unit 50 provided in the contact oxidation tank 20 is used to purify the tank downstream of the contact oxidation tank 20, and to purify the downstream tank. The sewage inside the tank can be disinfected.
For example, a slightly larger amount of sodium hypochlorite is generated by electrolysis than the amount of ammonia contained in the wastewater in the wastewater purification device 1. Thereby, sodium hypochlorite that does not react with ammonia remains.
By flowing this sodium hypochlorite into the downstream tanks, each tank can be purified and the sewage in each tank can be sterilized.

In this case, it is preferable to know the content of sodium hypochlorite in tanks downstream of the contact oxidation tank 20 so that the remaining sodium hypochlorite does not have a negative effect on oyster shells and microorganisms. . Therefore, it is preferable to include the chlorine concentration measuring section 52 in tanks other than the contact oxidation tank 20.
Note that the chlorine concentration measurement unit 52 does not need to be provided in all tanks downstream of the contact oxidation tank 20. As appropriate, the chlorine concentration measuring section 52 can be provided only in necessary tanks.

In the second settling tank 34, if the wastewater in the tank contains a sufficient amount of sodium hypochlorite for disinfection, the disinfectant section 40 may not supply disinfectant. can. This is because the sodium hypochlorite contained in wastewater can disinfect the wastewater.

≪Other embodiments≫
In the first embodiment, the sewage purification device 1 was described in which the contact oxidation tank 20 was equipped with the electrolysis unit 50 and the first contact filtration tank 30 was equipped with the honeycomb filter medium 76.
However, the sewage purification device 1 can be modified in various ways. Other embodiments will be illustrated below.

≪Embodiment 2≫
The sewage purification device 1 may be a sewage purification device 1 in which the electrolysis section 50 and the chlorine concentration measurement section 52 are not provided in the contact oxidation tank 20. This sewage purification device 1 is referred to as the sewage purification device 1 of the second embodiment.
In the sewage purification device 1 of the second embodiment, sodium hypochlorite is introduced from outside the tank in order to remove ammonia in the contact oxidation tank 20. Thereby, ammonia contained in the wastewater can be removed from the wastewater as nitrogen gas.
Alternatively, sodium hypochlorite may not be introduced into the contact oxidation tank 20 from outside the tank. In this case, for example, ammonia is removed from the wastewater in the first contact filtration tank 30. This is because the honeycomb filter medium 76 provided in the first contact filtration tank 30 has nitrifying bacteria attached to it.

≪Embodiment 3≫
As another embodiment, the sewage purification device 1 may be such that the first contact filtration tank 30 is not equipped with the honeycomb filter medium 76. This sewage purification device 1 is referred to as the sewage purification device 1 of the third embodiment.
In the sewage purification device 1 of Embodiment 3, the first contact filtration tank 30 can be made similar to the second contact filtration tank 32. Specifically, oyster shells are also placed in the first contact filtration tank 30.
In this case, ammonia cannot be nitrified by the nitrifying bacteria attached to the honeycomb filter medium 76.
However, when the catalytic oxidation tank 20 is equipped with the electrolysis section 50, ammonia can be removed in the catalytic oxidation tank 20 as described above.

It is also possible to attach nitrifying bacteria to the surface of oyster shells. For example, by attaching nitrifying bacteria to oyster shells in the first contact filtration tank 30, ammonia can be nitrified in the first contact filtration tank 30. In this case, in the tank immediately before the second contact filtration tank 32, the ammonia concentration in the wastewater in the tank can be reduced. Thereby, the oyster shells provided in the second contact filtration tank 32 can be protected.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various changes and modifications can be made.

1 Sewage purification equipment 2 Water usage equipment 5 Piping
10 Sedimentation separation tank 20 Contact oxidation tank 22 First settling tank 30 First contact filtration tank 301 Bottom of first contact filtration tank 302 Upper part of first contact filtration tank 32 Second contact filtration tank 34 Second settling tank 36 Storage tank 38 Surplus water storage tank 40 Disinfection section 50 Electrolysis section 52 Chlorine concentration measuring section 60 Oyster shell 62 Activated carbon 70 First porous tube 701 Hole 72 Sheet filter 74 Plastic filter medium 741 Mesh filter medium 76 Honeycomb filter medium 761 Hollow tube 78 Grating 80 No. 2-hole pipe 801 Hole 802 Bubbles 82 Block 90 Sediment 100 Water reuse system T1 Primary treatment T2 Secondary treatment T3 Tertiary treatment

Claims

Equipped with a contact filtration tank and an electrolysis tank for purifying wastewater,
The electrolysis tank is arranged upstream of the contact filtration tank,
The contact filtration tank includes oyster shells,
The electrolysis tank includes an electrolysis section,
The wastewater in the electrolyzer contains sodium chloride and water,
The electrolysis unit generates sodium hypochlorite by electrolyzing wastewater in the electrolysis tank,
Sewage purification equipment.
The wastewater in the electrolyzer contains ammonia,
At least a portion of the ammonia reacts with the sodium hypochlorite produced by the electrolysis to produce nitrogen.
The sewage purification device according to claim 1.
At least one tank of the electrolytic tank and a tank disposed upstream of the electrolytic tank includes a chlorine concentration measuring section,
The chlorine concentration measuring unit measures the chlorine concentration of wastewater in the tank provided with the chlorine concentration measuring unit,
The sewage purification device according to claim 1 or 2.
At least one of the tanks arranged downstream of the electrolysis tank includes a chlorine concentration measuring section,
The chlorine concentration measuring unit measures the chlorine concentration of wastewater in the tank provided with the chlorine concentration measuring unit,
The sewage purification device according to any one of claims 1 to 3.
The wastewater contains E. coli,
The E. coli is sterilized by the sodium hypochlorite produced by the electrolysis.
The sewage purification device according to any one of claims 1 to 4.
The electrolysis section includes a first electrode and a second electrode,
The first electrode and the second electrode are capable of reversing their polarities;
The sewage purification device according to any one of claims 1 to 5.