JP4017333B2 - Sewage treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sewage treatment apparatus, and more particularly to a sewage treatment apparatus that causes a phosphorus component in sewage to react with metal ions to aggregate by adding metal ions to the sewage.
[0002]
[Prior art]
In a conventional sewage treatment apparatus, a metal ion is generated by adding a flocculant or the like in the tank, and the phosphorus component in the sewage is reacted with the metal ion to cause aggregation and precipitation, thereby causing the sewage to flow. The phosphorus component of was removed.
[0003]
[Problems to be solved by the invention]
However, in the conventional sewage treatment apparatus, agglomerates containing phosphorus components are precipitated together with the sludge. In addition, it is difficult to isolate | separate the aggregate of the phosphorus component which precipitated with sludge from sludge. In other words, it has been difficult for a conventional sewage treatment apparatus to take out agglomerates of phosphorus components and to purify and recycle phosphorus therefrom. This was viewed as a problem as the need for phosphorus recycling increased.
[0004]
The present invention has been conceived in view of such circumstances, and an object of the present invention is to provide a sewage treatment apparatus capable of recovering a phosphorus component in sewage in a recyclable state.
[0005]
[Means for Solving the Problems]
The sewage treatment apparatus according to the present invention is provided with an electrode pair provided with an electrolytic cell for eluting iron ions, and by supplying the iron ions to the sewage, the components in the sewage are reacted with the iron ions. Having a constitution of aggregating a hardly soluble metal salt containing FePO ₄ , Fe ₂ O ₃ and Fe ₃ O ₄ ;
A magnetic processing unit for introducing sewage in the electrolytic cell is installed on the downstream side of the electrolytic cell,
The magnetic processing unit is composed of a case and a magnetic member installed in the case,
The case is provided with an introduction pipe and a discharge pipe at the top thereof, and the sewage introduced from the introduction pipe rises through the vicinity of the magnetic member after once descending to the bottom side in the case, It is configured to be discharged from the discharge pipe,
In the magnetic processing unit, Fe ₂ O ₃ and Fe ₃ O ₄ contained in the aggregated metal salt are attracted by the magnetic member, so that they are contained in the metal salt together with Fe ₂ O ₃ and Fe ₃ O _4. FePO ₄ is attracted to the magnetic member, and FePO ₄ is separated from sewage .
[0006]
According to the present invention, the agglomerates produced by the reaction of the phosphorus component in the sewage with metal ions are attracted to the magnetic member.
[0007]
Therefore, the above-mentioned aggregate can be separated and recovered from the sludge. That is, the aggregate produced by the reaction of the phosphorus component in the sewage with the metal ions can be collected efficiently and in a recyclable state.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, although the sewage treatment apparatus of each embodiment shown below is mainly applied to the large-scale wastewater treatment facility which processes domestic wastewater and factory wastewater, it is small and medium-sized, such as a domestic combined septic tank. It can also be applied to other wastewater treatment facilities. Moreover, according to the sewage treatment apparatus of each embodiment, the phosphorus compound contained in the domestic waste water, the waste water of a plating factory, etc. can be coagulated and settled.
[0020]
[First embodiment]
FIG. 1 is a longitudinal sectional view of a sewage treatment system including a sewage treatment apparatus according to a first embodiment of the present invention.
[0021]
Referring to FIG. 1, the sewage treatment system of the present embodiment is mainly composed of a tank 1. The tank 1 is buried in the ground. The inside of the tank 1 is divided into a first anaerobic filter bed tank 5, a second anaerobic filter bed tank 10, and a contact backing tank by a first partition wall 2, a second partition wall 3, a third partition wall 4 and a fourth partition wall 20. 14 is divided into a sedimentation tank 19 and a disinfection tank 21. The upper portion of the tank 1 is covered with a plurality of manholes 28. Further, the members inside the tank 1 are connected to members outside the tank 1 (such as the third blower 30). In FIG. 1, members outside the tank 1 such as the third blower 30 are shown above the tank 1 for convenience, but these members are not necessarily installed above the tank 1. is not.
[0022]
The first anaerobic filter bed tank 5 is provided with an inlet 6 into which domestic wastewater flows, and a first anaerobic filter bed 7 is disposed therein. That is, the first anaerobic filter bed tank 5 is also a communicable matter removing tank in the present embodiment, because daily wastewater flows in. In the present embodiment, the first anaerobic filter bed tank 5 constitutes an inflow tank. In the first anaerobic filter bed tank 5, difficult-to-decompose impurities in domestic wastewater are precipitated and separated, and organic matter in domestic wastewater is anaerobically decomposed by anaerobic microorganisms attached to the first anaerobic filter bed 7. The Also, nitrate nitrogen is reduced to nitrogen gas.
[0023]
The first anaerobic filter bed tank 5 is provided with a first advection pipe 8. A first water supply port 9 is formed in the upper part of the first partition wall 2. One end of the first advection pipe 8 is disposed in the first anaerobic filter bed tank 5 and the other end is disposed in the second anaerobic filter bed tank 10. The treated water that has been anaerobically decomposed in the first anaerobic filter bed tank 5 is supplied to the retreating second anaerobic filter bed tank 10 via the first advection pipe 8.
[0024]
The second anaerobic filter tank 10 is provided with a second anaerobic filter bed 11. The second anaerobic filter bed 11 captures suspended substances, anaerobic microorganisms anaerobically decompose organic substances, and nitrate nitrogen is reduced to nitrogen gas.
[0025]
The second anaerobic filter bed tank 10 is provided with a second advection pipe 12. An ejection device 32 is attached to the upper part of the second advection pipe 12. The ejection device 32 is connected to the third blower 30. In addition, the ejection device 32 connects the second anaerobic filter bed tank 10 and the contact backing tank 14 through the second water supply port 13 penetrating the upper part of the second partition wall 3.
[0026]
The ejection device 32 blows air from the ejection port 31 into the second advection pipe 12 by sending air from the third blower 30. Thereby, supply of the treated water from the 2nd anaerobic filter bed tank 10 to the contact backing tank 14 in the 2nd advection pipe 12 is accelerated | stimulated.
[0027]
The contact backing tank 14 includes a contact material 15. The contact material 15 is provided to promote the culture of aerobic microorganisms. A first air diffuser 16 is provided near the bottom of the contact back tank 14.
[0028]
The upper end of the first air diffuser 16 is connected to the first blower 17. A plurality of holes are formed on the lower surface side of the first air diffuser 16. And if air is sent from the 1st blower 17, this air will be discharge | released as a bubble from this hole. In addition, by forming a hole on the lower surface side of the first air diffuser 16, sludge is less likely to enter the inside than when a hole is formed on the upper surface or the side surface.
[0029]
As bubbles are released from the first air diffuser 16, the contact backing tank 14 is maintained in an aerobic state. As a result, in the contact back tank 14, the treated water is aerobically decomposed by aerobic microorganisms and nitrified, and ammonia nitrogen is decomposed into nitrate nitrogen. The aerobic microorganisms in the contact back tank 14 include nitrifying bacteria. In general, nitrifying bacteria refer to ammonia oxidizing bacteria and nitrite bacteria.
[0030]
The contact material 15 is attached with a biofilm that has grown and gradually becomes larger. And when a bubble is discharge | released from the 1st diffuser tube 16, the biofilm adhering to the contact material 15 will peel.
[0031]
A pump 33 is provided at the bottom of the contact back tank 14. A sludge return path 34 is connected above the pump 33, and a sludge return path 35 is connected to the upper end of the sludge return path 34 so as to extend to the left side of the figure. Thereby, the sludge produced in the contact back tank 14 is sent to the first anaerobic filter bed tank 5.
[0032]
A disinfection tank 21 is provided on the upper part of the precipitation tank 19. The disinfection tank 21 is configured so that the supernatant of the precipitation tank 19 flows. The sterilization tank 21 is provided with a sterilizer 22. The sterilizer 22 is provided with chemicals such as chlorine. The treated water that has flowed into the sterilization tank 19 is sterilized by the chemical and is discharged out of the tank 1 through the drain port 23.
[0033]
The settling tank 19 is provided with a third advection pipe 38 and a pump 39. The treated water in the contact back tank 14 flows into the settling tank 19 via the third advection pipe 38. This flow is promoted by the pump 39.
[0034]
The settling tank 19 and the first anaerobic filter bed tank 5 are connected by a first return pipe 24. The first return pipe 24 includes a second air diffuser pipe 25 therein. The second air diffuser 25 is connected to the second blower 26. The second air diffuser 25 is appropriately formed with an ejection hole for ejecting air. The second air diffuser 25 ejects the air supplied from the second blower 26 from the ejection holes, and the treated water in the settling tank 19 is passed through the first return pipe 24 to the first anaerobic filter bed. Feed into tank 5.
[0035]
An electrolytic cell 59 is provided above the first anaerobic filter bed 5. The electrolytic bath 59 is introduced with sewage from the first return pipe 24. Electrode pairs 51 and 52 are provided inside the electrolytic cell 59. The electrode pairs 51 and 52 are each connected to a power source 57.
[0036]
In the electrolytic bath 59, metal ions such as iron ions and aluminum ions are eluted by electrolysis (appropriately abbreviated as electrolysis) in the electrode pairs 51 and 52. As a result, in the electrolytic bath 59, the eluted metal ions react with the phosphorus compound or the like in the treated water to form a metal salt that is hardly soluble in water and aggregates. When iron ions are eluted as metal ions, the difficult-to-tolerate metal salts are mainly “FePO ₄ ”, “Fe (OH) ₃ ”, “FeOOH”, “Fe ₂ O ₃ ”, and , “Fe ₃ O ₄ ”. That is, when iron ions are supplied to the sewage, the above five types of compounds are mainly aggregated.
[0037]
A magnetic processing unit 60 is installed on the downstream side of the electrolytic bath 59. The sewage in the electrolytic bath 59 flows into the magnetic processing unit 60.
[0038]
In the magnetic processing unit 60, the sewage comes into contact with the magnet. Note that Fe ₂ O ₃ and Fe ₃ O ₄ are attracted to the magnet. That is, the aggregate produced by supplying iron ions to the sewage is attracted to the magnet because it contains Fe ₂ O ₃ and Fe ₃ O ₄ . Thereby, FePO ₄ aggregated together with Fe ₂ O ₃ and Fe ₃ O ₄ is also attracted to the magnet and separated from the sewage.
[0039]
After being processed by the magnetic processing unit 60, the sewage is sent again to the first anaerobic filter bed 5.
[0040]
Next, the configuration of the magnetic processing unit 60 will be described in detail with reference to FIGS. 2 and 3. FIG. 2 is a diagram schematically showing a longitudinal section of the magnetic processing unit 60. FIG. 3 is a plan view of the magnetic processing unit 60.
[0041]
The magnetic processing unit 60 mainly includes a case 61 and a magnet 62 installed in the case 61. The magnet 62 has a cylindrical shape, and is fixed to the center of the case 61 by means (not shown). The magnet 62 is preferably a permanent magnet having a magnetic line density of about 10,000 gauss.
[0042]
The case 61 is provided with an introduction pipe 61A and a discharge pipe 61B. In the case 61, a partition plate 611 is provided in the vicinity of the introduction pipe 61A, and a 612 is provided in the vicinity of the discharge pipe 61B. The partition plate 611 extends in the height direction from the position where the introduction pipe 61 </ b> A is connected to the case 61 to the vicinity of the bottom of the case 61. Further, the partition plate 612 extends in the height direction from the position where the discharge pipe 61B is connected to the case 61 to the vicinity of the bottom of the case 61. As a result, the flow of sewage introduced into the case 61 is mainly as shown by the dashed arrows. That is, in the case 61, the sewage introduced from the introduction pipe 61 </ b> A first descends to the vicinity of the bottom of the case 61 along the partition plate 611. Thereafter, the sewage passes through the vicinity of the magnet 62, rises between the magnet 62 and the partition plate 62, and is discharged out of the case 61 from the discharge pipe 61 </ b> B.
[0043]
A solenoid 63 connected to the power supply device 630 is attached around the magnet 62. The solenoid 63 is provided to demagnetize the magnet 62 by applying an alternating magnetic field to the magnet 62. When the magnet 62 is appropriately demagnetized, aggregates including Fe ₂ O ₃ , Fe ₃ O ₄ , FePO _4, etc. attached to the magnet 62 are separated from the magnet 62 and fall to the bottom of the case 61 by their own weight. To do.
[0044]
On the other hand, a drain valve 610 is provided at the bottom of the case 61. In the magnetic processing unit 60, the magnet 62 is appropriately demagnetized using the solenoid 63 and the power supply device 630, and then the drain valve 610 is opened to separate FePO ₄ generated from the phosphorus component in the sewage from the sludge. Can be recovered.
[0045]
Note that the method of separating the aggregates attached to the magnet 62 from the magnet 62 is not limited to the method using the solenoid 63. Aggregates attached to the magnet 62 may be physically separated as shown in FIGS.
[0046]
That is, a cover 64 is provided around the magnet 62 instead of the solenoid 63. For example, as shown in FIG. 4, the cover 64 is set around the magnet 62 by moving the magnet 62 in a predetermined position in the case 61 and then moving the magnet 62 from above the magnet 62 in the direction of the arrow P <b> 1. The cover 64 has a cylindrical shape having substantially the same dimensions as the outer shell of the magnet 62. The cover 64 is attached with a handle 640 for moving the cover 64.
[0047]
When performing normal wastewater treatment, a cover 64 is attached to the magnet 62. The cover 64 is made of a material that is not magnetized by the magnet 62 (such as a plastic film). At this time, the aggregates adhere to the surface of the cover 64. Then, for example, when maintenance is performed periodically such as once a month, the magnet 62 is moved upward (in the direction of arrow P2) as shown in FIG. As a result, the aggregate attached to the surface of the cover 64 falls to the bottom of the case 61. Then, by opening the drain valve 610 (see FIG. 1), FePO ₄ can be recovered in a form separated from sludge.
[0048]
[Second Embodiment]
The sewage treatment apparatus of the present embodiment is obtained by changing only the detailed configuration of the magnetic treatment unit 60 from the sewage treatment apparatus of the first embodiment described above. Accordingly, only the configuration of the magnetic processing unit 60 of the present embodiment will be described here.
[0049]
FIG. 6 is a diagram schematically showing a longitudinal section of the magnetic processing unit 60 of the present embodiment, and FIG. 7 is a plan view of the magnetic processing unit 60 of FIG. The dashed arrows in FIG. 6 indicate the main sewage flow in the case 61.
[0050]
In the magnetic processing unit 60 of the present embodiment, a filter 65 is attached to the side surface of the magnet 62. The filter 65 is configured by knitting a paramagnetic material such as iron into a net.
[0051]
The filter 65 is magnetized by being attached in the vicinity of the magnet 62. Then, the sewage introduced into the case 61 flows through the filter 65 as indicated by the broken arrow in FIG. Therefore, the aggregate containing FePO ₄ , Fe ₂ O ₃ , Fe ₃ O _4, etc. adheres not only to the magnet 62 but also to the filter 65.
[0052]
The filter 65 can be removed from the magnet 62. That is, the filter 65 can be removed from the case 61. Then, by appropriately treating the removed filter 65 with acid, FePO ₄ can be recovered in a state separated from sludge.
[0053]
Also in this embodiment, the agglomerates attached to the magnet 62 can be recovered in a state separated from the sludge, as in the first embodiment.
[0054]
[Third embodiment]
The sewage treatment apparatus of the present embodiment is obtained by changing only the detailed configuration of the magnetic treatment unit 60 from the sewage treatment apparatus of the first embodiment described above. Accordingly, only the configuration of the magnetic processing unit 60 of the present embodiment will be described here.
[0055]
FIG. 8 is a diagram schematically showing a longitudinal section of the magnetic processing unit 60 of the present embodiment, and FIG. 9 is a plan view of the magnetic processing unit 60 of FIG. The broken-line arrows in FIG. 8 indicate the main sewage flow in the case 61.
[0056]
In the present embodiment, a case 66 is installed between the partition plate 611 and the partition plate 612. The case 66 has a plurality of perforations formed on the wall surface so that dirty water can pass through. The case 66 houses a magnet 62 having a granular shape. The particle size of the magnet 62 of the present embodiment is preferably about 2 mm to 20 mm. In addition, as the shape of the magnet 62 of the present embodiment, various shapes such as a pellet shape, a round shape, a square shape, a cylindrical shape, and a prismatic shape are conceivable.
[0057]
The sewage introduced into the case 61 passes through the case 66 from the bottom to the top, as indicated by the dashed arrows in FIG. As a result, the sewage comes into contact with the magnet 62 in the case 66, and aggregates containing FePO ₄ , Fe ₂ O ₃ , Fe ₃ O _4, etc. adhere to the magnet 62.
[0058]
The case 66 is configured to be removable from the case 61. Then, by appropriately removing the case 66 from the case 61 and treating the magnet 62 with acid, the FePO ₄ adhering to the magnet 62 can be recovered in a state separated from the sludge.
[0059]
[Fourth embodiment]
The sewage treatment apparatus of the present embodiment is obtained by changing only the detailed configuration of the magnetic treatment unit 60 from the sewage treatment apparatus of the first embodiment described above. Accordingly, only the configuration of the magnetic processing unit 60 of the present embodiment will be described here.
[0060]
FIG. 10 is a diagram schematically showing a longitudinal section of the magnetic processing unit 60 of the present embodiment. In addition, the arrow of the broken line in FIG. 10 has shown the main flows of sewage in the case 61. FIG.
[0061]
In the case 61, as in the third embodiment described with reference to FIGS. 8 and 9, a granular magnet 62 and a case 66 for housing the magnet 62 are installed.
[0062]
In the magnetic processing unit 60 of the present embodiment, the partition plates 611 and 612 and the case 66 are provided such that their longitudinal directions follow the flow of sewage indicated by broken lines, that is, inclined obliquely. Yes. Further, a deposition unit 67 is provided at the bottom of the case 61 and downstream of the case 66 with respect to the flow of sewage.
[0063]
The deposition unit 67 includes a receiving unit 670 that receives the aggregate in the sewage, and a lid 671 that covers the receiving unit 670.
[0064]
Thereby, the sewage introduced from the introduction pipe 61 </ b> A passes through the case 66 obliquely downward along the broken line from above the case 66.
[0065]
At this time, aggregates containing FePO ₄ , Fe ₂ O ₃ , Fe ₃ O _4, etc. in the sewage adhere to the magnet 62. Even in the case where the aggregate cannot be attached to the magnet 62 and flows together with sewage, the aggregate is attracted to the magnet 62, so that the distance flowing through the case 66 increases. The flow velocity is lower than the surrounding sewage. And since the flow rate has fallen from the surrounding sewage, the aggregate which passed through the case 66 falls, without rising to the discharge pipe 61B, and is accommodated in the receiving part 670.
[0066]
Thereby, in the magnetic processing unit 60 of the present embodiment, the agglomerates that could not be attached to the magnet 62 can be further collected by being deposited on the deposition unit 67. The case 66 and the deposition unit 67 are configured to be removable from the case 61. In addition, when removing the deposition unit 67 from the case 61, it is preferable to cover the receiving part 670 with the cover part 671. In addition, the receiving unit 670 can cover the entire top surface of the lid 671.
[0067]
Further, as shown in FIG. 11, a collection unit 69 may be provided below the case 61 instead of the deposition unit 67. The collection unit 69 has a shape capable of receiving the aggregate falling from above.
[0068]
A valve 68 is provided at the bottom of the case 61 shown in FIG. Then, by opening the valve 68 as appropriate, the aggregate accumulated at the bottom of the case 61 can be moved to the recovery unit 69. In other words, in this case, the recovery unit 69 should be installed only at least when the valve 68 is opened. The collection unit 69 is configured to be removable from the tank 1.
[0069]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a sewage treatment system including a sewage treatment apparatus according to a first embodiment of the present invention.
2 is a longitudinal sectional view of a magnetic treatment unit of the sewage treatment apparatus of FIG. 1. FIG.
FIG. 3 is a plan view of a magnetic treatment unit of the sewage treatment apparatus of FIG. 1;
FIG. 4 is a diagram for explaining a modification of the first embodiment of the present invention.
FIG. 5 is a diagram for explaining a modification of the first embodiment of the present invention.
FIG. 6 is a longitudinal sectional view of a magnetic treatment unit in the sewage treatment apparatus according to the second embodiment of the present invention.
FIG. 7 is a plan view of a magnetic treatment unit in the sewage treatment apparatus according to the second embodiment of the present invention.
FIG. 8 is a longitudinal sectional view of a magnetic treatment unit in the sewage treatment apparatus according to the third embodiment of the present invention.
FIG. 9 is a plan view of a magnetic treatment unit in the sewage treatment apparatus according to the third embodiment of the present invention.
FIG. 10 is a longitudinal sectional view of a magnetic treatment unit in a sewage treatment apparatus according to a fourth embodiment of the present invention.
11 is a longitudinal sectional view of a modification of the magnetic processing unit of FIG.
[Explanation of symbols]
1 tank, 5 first anaerobic filter bed tank, 10 second anaerobic filter bed tank, 51, 52 electrode pair, 60 magnetic processing unit, 61 case, 62 magnet, 64 cover, 65 filter, 67 deposition unit, 69 recovery unit.

Claims (1)

An electrode pair is provided, and an electrolytic cell for eluting iron ions is provided. By supplying the iron ions to sewage, the components in the sewage react with the iron ions to form FePO. ₄ , Fe ₂ O ₃ And Fe ₃ O ₄ Having a constitution of agglomerating a hardly soluble metal salt containing
A magnetic processing unit for introducing sewage in the electrolytic cell is installed on the downstream side of the electrolytic cell,
The magnetic processing unit is composed of a case and a magnetic member installed in the case,
The case is provided with an introduction pipe and a discharge pipe at the top thereof, and the sewage introduced from the introduction pipe rises through the vicinity of the magnetic member after once descending to the bottom side in the case, It is configured to be discharged from the discharge pipe,
In the magnetic processing unit, Fe contained in the aggregated metal salt ₂ O ₃ And Fe ₃ O ₄ By attracting the magnetic member, Fe ₂ O ₃ And Fe ₃ O ₄ Together with FePO contained in the metal salt ₄ Is attracted to the magnetic member, and FePO ₄ A sewage treatment apparatus, wherein the sewage is separated from the sewage.

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