JP3754167B2 - Sewage treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sewage treatment apparatus that purifies sewage, and more particularly to a sewage treatment apparatus that removes phosphorus from sewage.
[0002]
[Prior art]
As this type of sewage treatment apparatus, for example, JP-A-7-108296 (C02F 3/30) is known. This sewage treatment device elutes iron ions in the sewage supplied from the aerobic tank to the anaerobic tank and returns it to the anaerobic tank, and reacts the iron ions eluted from the elution tank with orthophosphoric acid in the sewage to form a water-insoluble phosphorus compound. Aggregates and precipitates to remove phosphorus from wastewater.
[0003]
However, there is a drawback that the elution efficiency of iron ions decreases due to the gradual accumulation of phosphorus compounds, etc. produced by reaction with sludge and orthophosphoric acid in sewage after long-term use, and the deposit touches the electrode. was there.
[0004]
[Problems to be solved by the invention]
This invention is made | formed in order to solve the said subject, and makes it a subject to provide the sewage treatment apparatus which can maintain the stable phosphorus removal performance.
[0005]
[Means for Solving the Problems]
The first means for solving the above-mentioned problem is to have a treatment tank having an anaerobic part, an aerobic part and a precipitation part, and an electrode made of iron material or aluminum, and elute iron ions or aluminum ions by energizing the electrodes. An elution tank, a transfer means for supplying the sewage in the treatment tank to the elution tank, and a discharge port for returning the sewage supplied to the elution tank to the treatment tank. The discharge port is provided above the sewage in the treatment tank and at a position lower than the electrode.
[0006]
The second means for solving the above-mentioned problem is to have a treatment tank having an anaerobic part, an aerobic part and a precipitation part, and an electrode made of iron material or aluminum. An elution tank, a transfer means for supplying the sewage in the treatment tank to the elution tank, and a discharge port for returning the sewage supplied to the elution tank to the treatment tank. A discharge port is provided above the sewage in the treatment tank and at the bottom of the elution tank.
[0007]
The third means for solving the above-mentioned problem is to have a treatment tank having an anaerobic part, an aerobic part and a precipitation part, and an electrode made of iron material or aluminum, and elute iron ions or aluminum ions by energizing the electrodes. An elution tank whose bottom is inclined, a transfer means for supplying the sewage in the treatment tank to the elution tank, and a discharge port for returning the sewage supplied to the elution tank to the treatment tank. The discharge port of the elution tank is provided above the sewage in the treatment tank and in the vicinity of the lowest position of the bottom of the elution tank.
[0008]
In the first to third means, it is preferable to provide a control means for stopping energization of the transfer means and the electrodes.
[0009]
In the first to third means, the inspection tank includes an inspection opening in the upper portion of the processing tank, and a lid for closing the inspection opening so as to be openable and closable, and the elution tank is located near the inspection opening. It is preferable to provide in.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described in detail below based on the sewage treatment apparatus shown in FIGS.
[0011]
Reference numeral 1 denotes a treatment tank buried in the ground. The inside of the treatment tank 1 is divided into a first anaerobic part 5, a second anaerobic part 18, an aerobic part 22, a sedimentation part 28, and a disinfecting part by a first partition wall 2, a second partition wall 3 and a third partition wall 4. There are 30 sections.
[0012]
Reference numeral 5 denotes a first anaerobic part having an inlet 6 through which sewage such as domestic wastewater flows, and 7 denotes a first anaerobic filter bed disposed in the first anaerobic part 5, which flows into the first anaerobic part 5. The hard-to-decompose contaminants mixed in the sewage are precipitated and separated, anaerobic microorganisms attached to the first anaerobic filter bed 7 are anaerobically decomposed, and organic nitrogen is anaerobically decomposed into ammonia nitrogen. To do.
[0013]
8 is a rectangular box-shaped elution tank disposed above the sewage of the first anaerobic part 5 and facing a first inspection opening 49 which will be described later. The bottom part is inclined toward the center of the bottom part and the center of the bottom part. The discharge port 9 is provided, and the sewage supplied from the diversion device 49 is returned from the discharge port 9 to the first anaerobic part 5 through a third return pipe 45 described later. An exhaust port 10 is provided at the upper part of the elution tank 8 and discharges air in the elution tank 8.
[0014]
Reference numeral 11 denotes an electrode cover having an electrode 12 made of an iron material disposed in the elution tank 8 and formed of a transparent insulator that closes the elution tank 8. Reference numeral 13 denotes a power supply device that is controlled by a control circuit 55, which will be described later, and supplies a constant DC current between the electrodes 12. By supplying a constant DC current from the power supply device 13 between the electrodes 12, the sewage in the elution tank 8 is supplied. Elute iron ions. The elution tank 8, the electrode 12 and the power supply device 13 constitute an elution apparatus.
[0015]
Reference numeral 14 denotes a first air diffuser disposed between the electrodes 12 at the bottom of the elution tank 8, which forms a large number of air outlets, is connected to the first blower 15, and is supplied from the first blower 15. By discharging air from the air outlet, the electrode 12 is washed to prevent sludge from adhering, and the divalent iron ions eluted from the electrode 12 are oxidized to trivalent iron ions that react with orthophosphoric acid.
[0016]
Reference numeral 16 denotes a first advection pipe disposed in the first anaerobic part 5, and the sewage that has been anaerobically decomposed by the first anaerobic part 5 is passed through a first water supply port 17 penetrating the upper part of the first partition wall 2. And supplied to a second anaerobic section 18 to be described later.
[0017]
Reference numeral 18 denotes a second anaerobic part partitioned from the first anaerobic part 5 by the first partition wall 2, and 19 denotes a second anaerobic filter bed disposed in the second anaerobic part 18, the second anaerobic filter bed. 19 traps suspended solids and anaerobically decomposes organic matter by anaerobic microorganisms, and anaerobically decomposes organic nitrogen to ammonia nitrogen.
[0018]
Reference numeral 20 denotes a second advection pipe disposed in the second anaerobic part 18, and the sewage decomposed anaerobically in the second anaerobic part 18 is passed through a second water supply port 21 penetrating the upper part of the second partition wall 3. Then, water is supplied to the aerobic part 22 described later. Reference numeral 22 denotes an aerobic part partitioned from the second anaerobic part 18 by the second partition wall 3, and the sewage treated by the second anaerobic part 18 flows in through the second advection pipe 20. Reference numeral 23 denotes a contact material disposed in the aerobic part 22 and promotes culture of aerobic microorganisms.
[0019]
Reference numeral 24 denotes a second air diffuser disposed at the bottom of the aerobic part 22, which forms a large number of air outlets, is connected to the second blower 25, and air supplied from the second blower 25 is used as an air outlet. The aerobic part 22 is maintained in an aerobic state by releasing from the sewage, and the sewage is aerobically decomposed by aerobic microorganisms, and ammonia nitrogen is converted to nitrate or nitrite nitrogen by the action of nitrate bacteria and nitrite bacteria. Disassembled into
[0020]
Reference numeral 26 denotes a third air diffuser disposed below the contact material 23 and having a number of air outlets, and is connected to the second blower 25. The air from the second blower 25 is supplied to either the second air diffuser 24 or the third air diffuser 26 by the first electromagnetic valve 27.
[0021]
The first electromagnetic valve 27 is normally switched to the second air diffuser 24, and the air supplied from the second blower 25 is discharged from the air outlet of the second air diffuser 24 so that the aerobic portion 22 is in an aerobic state. When the contact material 23 is washed, the control circuit 55, which will be described later, switches the first electromagnetic valve 27 to the third air diffuser 26 and releases air from the air outlet of the third air diffuser 26, The biofilm that adheres to the contact material 23 and grows and gradually thickens is peeled off.
[0022]
28 is a sedimentation part which communicates with the aerobic part 22 through the communication port 29 provided at the bottom of the third partition wall 4. The sewage which is aerobically decomposed at the aerobic part 22 and flows from the communication port 29 is separated into sediment and supernatant. To separate. Further, in order to return the sludge accumulated on the bottom of the sedimentation part 28 from the communication port 29 to the aerobic part 22, the bottom of the sedimentation part 28 is inclined toward the aerobic part 22 side.
[0023]
Reference numeral 30 denotes a disinfecting unit provided at the upper part of the settling unit 28, and the supernatant liquid separated in the settling unit 28 flows in. 31 is a sterilization device provided in the sterilization unit 30, and disinfects the sewage that has flowed into the sterilization unit 30 with chemicals such as chlorine based in the sterilization device 31. 32 is a drain opening communicating with the sterilization unit 30, and the sewage sterilized in the sterilization unit 30 is drained out of the treatment tank 1.
[0024]
33 is a first return pipe that communicates the bottom of the aerobic part 22 and the upper part of the first anaerobic part 5, and 34 is a fourth aeration pipe disposed in the first return pipe 33 at the bottom of the aerobic part 22. In addition, the sludge accumulated in the bottom of the aerobic part 22 and the sedimentation part 28 are connected to the third blower 35 and air supplied from the third blower 35 is discharged from the air blower outlet. The sludge returned to the aerobic part 22 is returned to the first anaerobic part 5 via the first return pipe 33.
[0025]
Reference numeral 36 denotes a second return pipe that communicates with the upper part of the settling portion 28 and an inflow chamber 40 of a water diversion meter 39, which will be described later. Reference numeral 37 denotes a fifth diffuser pipe disposed in the second return pipe 36. A blower outlet is formed and connected to the third blower 35. Air from the third blower 35 is supplied to either the fourth air diffuser 34 or the fifth air diffuser 37 by the second electromagnetic valve 38.
[0026]
The second solenoid valve 38 is normally switched to the fifth air diffuser 37 and discharges the air supplied from the third blower 35 from the air outlet of the fifth air diffuser 37, so that the supernatant liquid in the precipitation unit 28 is discharged. Is transferred to an inflow chamber 40 of a water metering device 39, which will be described later, through a second return pipe 36.
[0027]
After cleaning the contact material 23, the control circuit 55 switches the second electromagnetic valve 38 to the fourth air diffuser 34, and discharges air from the air outlet of the fourth air diffuser 34. Sewage flows into the first anaerobic part 5 through the first return pipe 33. Accompanying this flow, the sludge accumulated at the bottom of the aerobic part 22 and the sediment returned from the precipitation part 28 to the aerobic part 22 are returned to the first anaerobic part 5 via the first return pipe 33.
[0028]
39 is a rectangular box-shaped water metering device disposed at the upper part of the settling portion 28, and has an inflow chamber 40 connected to the second return pipe 36 and an opening communicating the lower side with the inflow chamber 40. An intermediate chamber 42 partitioned by a partition wall 41 is divided into a first water diversion chamber 43 and a second water diversion chamber 44 into which sewage in the intermediate chamber 42 flows.
[0029]
The first water diversion chamber 43 communicates with the elution tank 8 via a third return pipe 45, and communicates with the intermediate chamber 42 by a notch 46 whose upper portion of the wall is opened in a V shape. The second water diversion chamber 44 communicates with the upper portion of the aerobic portion 22 through a pipe 47 and communicates with the intermediate chamber 42 through an opening formed in the upper portion of the overflow dam plate 48 whose height can be adjusted.
[0030]
Adjust the height of the overflow dam plate 48, change the size of the opening formed in the upper part of the overflow dam plate 48, and set the amount of sewage returned from the second diversion chamber 44 to the aerobic part 22. Thus, the amount of sewage flowing from the first water diversion chamber 43 into the elution tank 8 can be adjusted.
[0031]
49 is a first inspection opening provided at a position facing the first anaerobic part 5, the second anaerobic part 18 and the elution tank 8 at the upper part of the first partition wall 2, and 50 is for opening and closing the first inspection opening 49. The first lid that can be freely closed is opened and closed during suction and removal of sludge accumulated on the bottoms of the first anaerobic part 5 and the second anaerobic part 18 and during maintenance of the electrode 12 of the elution tank 8.
[0032]
Reference numeral 51 denotes a second inspection opening provided at a position facing the aerobic portion 22, and 52 denotes a second lid that closes the second inspection opening 51 so as to be freely opened and closed. 53 is a third inspection opening provided at a position facing the sterilizing device 31, and 54 is a third lid for closing the third inspection opening 53 so that it can be opened and closed. It opens and closes when replenishing.
[0033]
A control circuit 55 controls the first blower 15, the second blower 25, the third blower 35, the power supply device 13, the first electromagnetic valve 27, the second electromagnetic valve 38, and the like.
[0034]
Thus, the sewage discharged from the home flows into the first anaerobic part 5 from the inflow port 6, and the toilet paper or the like in the sewage by the first anaerobic filter bed 7 disposed in the first anaerobic part 5. The relatively coarse solids and impurities are removed, and a preliminary treatment for smoothly performing the treatment in each treatment tank to be introduced later is performed, and the removed solids, impurities and the first anaerobic filter bed are performed. The sewage passing through 7 is anaerobically decomposed by the action of anaerobic microorganisms, BOD is reduced, and sludge generated by the decomposition of the sewage accumulates at the bottom of the first anaerobic part 5. Also, anaerobic microorganisms anaerobically decompose organic nitrogen into ammonia nitrogen.
[0035]
As new sewage flows into the first anaerobic part 5, the sewage decomposed anaerobically at the first anaerobic part 5 flows into the second anaerobic part 18 from the first water supply port 17 of the first advection pipe 16. The sewage flowing into the second anaerobic part 18 is subjected to anaerobic microorganisms in the second anaerobic filter bed 19 to reduce the BOD, and sludge generated by the sewage decomposition is reduced to the second anaerobic part. 18 Deposit at the bottom. Also, anaerobic microorganisms anaerobically decompose organic nitrogen into ammonia nitrogen.
[0036]
As new sewage flows into the second anaerobic part 18, sewage decomposed anaerobically in the second anaerobic filter bed 19 flows into the aerobic part 22 from the second water supply port 21 of the second advection pipe 20, and the second blower 25 The air supplied from the air is agitated by being discharged from the air outlet of the second air diffuser 24.
[0037]
Then, oxygen is dissolved in the sewage, and the aerobic microorganisms adhered to the surface of the contact material 23 aerobically decompose the sewage, decompose organic phosphates etc. into orthophosphoric acid, and convert ammonia nitrogen into nitric acid. Decomposes into nitrous acid and nitrite. In addition, sludge generated by the decomposition of sewage accumulates at the bottom of the aerobic part 22.
[0038]
As new sewage flows into the aerobic part 22, the sewage aerobically decomposed by the action of aerobic microorganisms attached to the contact material 23 flows into the sedimentation part 28 from the communication port 29 at the bottom of the aerobic part 22. The sewage that has flowed into the sedimentation section 28 settles while the ascending inside the sedimentation section 28, and is returned to the aerobic section 22 through the communication port 29, and the supernatant liquid flows into the disinfection section 30. The supernatant liquid that has flowed into the sterilization unit 30 is sterilized by a sterilization apparatus 31 equipped with chlorinated chemicals, kills bacteria such as pathogenic bacteria, and is drained from the treatment tank 1 through the drain port 32.
[0039]
By discharging the air supplied from the third blower 35 from the air outlet of the fifth diffuser pipe 37, the supernatant liquid in the settling portion 28 flows into the inflow chamber 40 of the diversion device 39, and in the intermediate chamber 42. The flow is rectified and flows into the first water diversion chamber 43 and the second water diversion chamber 44.
[0040]
In the sewage flowing into the elution tank 8 from the first water diversion chamber 43 through the third return pipe 45, iron ions are eluted from the electrodes 12 by supplying a constant DC current between the electrodes 12 made of iron. . The eluted iron ions react with orthophosphoric acid and aggregate and precipitate as a water-insoluble phosphorus compound.
[0041]
Further, the nitrate or nitrite nitrogen in the sewage returned to the first anaerobic part 5 is reduced by the denitrifying bacteria present in the first anaerobic part 5 and diffused and removed as nitrogen gas in the air. The
[0042]
The sewage returned from the elution tank 8 to the first anaerobic section 5 is supplied from the sedimentation section 28, not from the aerobic section 22 having an extremely high dissolved oxygen concentration. Even if it returns to the anaerobic part 5, there is little influence with respect to anaerobic microorganisms, and anaerobic processing can be performed.
[0043]
The biofilm formed by aerobic microorganisms attached to the contact material 23 grows and gradually thickens. Therefore, in order to prevent clogging, the control circuit 55 periodically controls the first solenoid valve 27 to control the second blower. The air supply from 25 is switched to the third air diffuser 26, and air is released from the air outlet of the third air diffuser 26 to peel off the biofilm.
[0044]
When the air supply from the third air diffuser 26 is finished, the peeled biofilm accumulates as sludge on the bottom of the aerobic part 22, but the control circuit 55 controls the second electromagnetic valve 38 to supply the air from the third blower 35. By switching the air to the fourth air diffuser 34 and releasing the air from the air outlet of the fourth air diffuser 34, the first return pipe together with the sludge accumulated in the aerobic part 22 at the bottom of the aerobic part 22 It is returned to the first anaerobic part 5 via 33.
[0045]
The elution tank 8 is disposed so as to face the first inspection opening 49. When the first lid 50 is opened and the sludge accumulated in the first anaerobic part 5 and the second anaerobic part 18 is removed by suction, etc. The elution tank 8 can be inspected.
[0046]
Further, when the control circuit 55 stops the third blower 35 by operating an inspection switch (not shown), the sewage is not supplied from the diversion meter 39 to the elution tank 8, and all the sewage in the elution tank 8 is discharged to the outlet. 9 is returned to the first anaerobic tank 5 and the electrode 12 is exposed.
[0047]
Accordingly, the degree of wear of the electrode 12 can be easily confirmed through the transparent electrode cover 11, and the control circuit 55 stops the power supply device 13, so that an electric shock when replacing the electrode 12 can be prevented.
[0048]
Moreover, since the sludge in the elution tank 8 is returned to the first anaerobic tank 5 together with the sewage from the discharge port 9 provided at the bottom center of the elution tank 8, it is not necessary to perform the sludge treatment in the elution tank 8, It is possible to prevent a decrease in iron ion elution efficiency due to the sludge touching the electrode 12.
[0049]
Since hydrogen gas generated from the electrode 12 by electrolysis of the electrode 12 is lighter than air, it tends to accumulate in the upper part of the elution tank 8 and may explode if the hydrogen gas concentration in the elution tank 8 increases. Therefore, in this embodiment, the exhaust port 10 is provided in the upper part of the elution tank 8, and the hydrogen gas in the elution tank 8 is efficiently dissolved together with the air supplied from the first air diffuser 14 to the sewage in the elution tank 8. 8 is discharged outside to prevent the hydrogen gas concentration in the elution tank 8 from rising and to prevent an explosion.
[0050]
In the present embodiment, the discharge port 9 is provided at the center of the bottom of the elution tank 8, and the bottom is inclined toward the discharge port 9. For example, as shown in FIG. Even when the discharge port 9 is provided on the side wall of the elution tank 8 in the vicinity of the low position, the same effects as those of the present embodiment can be obtained. Further, the discharge port 9 of the elution tank 8 may be provided at a position lower than the electrode 12.
[0051]
In the embodiment of the present invention, when the electrode 12 made of iron is immersed in the sewage in the elution tank 8 for a long period of time, an oxide film is generated on the surface of the electrode, and it becomes a passivated state and the iron ions are eluted. Gradually decreases, dephosphorization performance decreases.
[0052]
Therefore, it is preferable to apply a constant DC current between a pair of electrodes made of iron and to change the polarity of the current every predetermined time. When used for a long period of time, an oxide film is generated on the surface of the iron material on the anode side, but the surface of the iron material on the cathode side is washed with hydrogen gas generated from the iron material on the cathode side, and no oxide film is formed. Therefore, the elution of iron ions can be maintained substantially constant by changing the polarity at a time interval until an oxide film is generated on the surface of the iron material on the anode side and the elution of iron ions is reduced. Can be kept constant.
[0053]
Moreover, in this structure, since both electrodes are made of iron material, iron ions are always eluted from the iron material serving as the anode side electrode and supplied to the sewage, so that the dephosphorization performance can always be maintained in a constant state. .
[0054]
Alternatively, an iron material may be used at least on the anode side of the electrode, a constant DC current may be applied between both electrodes, and the applied current may be increased in a pulsed manner every predetermined time. In this configuration, by increasing the applied current in a pulsed manner, the oxide film generated on the surface of the anode-side iron material can be peeled off, the elution of iron ions is maintained substantially constant, and the dephosphorization performance is kept constant. Can be maintained.
[0055]
Furthermore, it is good also as a structure which applies a direct-current constant current between a pair of electrodes which consist of iron materials, changes the polarity of the electric current for every predetermined time, and increases an applied current in a pulse form. When the time until the polarity change is long, an oxide film is formed on the surface of the iron material on the anode side. By changing the polarity, the oxide film can be removed by washing with hydrogen gas. Some time is required until peeling, and since the electric resistance until the oxide film is peeled off is large, power consumption may increase.
[0056]
Therefore, by increasing the applied current in a pulsed manner as described above, the oxide film on the iron material surface converted from the anode to the cathode can be removed in a short time, and an increase in power consumption can be prevented.
[0057]
In the embodiment of the present invention, an iron material is used as an electrode for eluting iron ions by applying a DC constant current. However, an iron material is used for the anode side electrode, and the cathode side electrode is made of titanium, platinum, or the like. Alternatively, the insoluble material may be used.
[0058]
Further, in the embodiment of the present invention, the iron material is used for both electrodes as an electrode for eluting iron ions by applying a DC constant current, but a configuration using aluminum may be used.
[0059]
【The invention's effect】
According to the configuration of the first aspect of the present invention, it is possible to prevent a decrease in ion elution efficiency eluted from the electrode due to the sludge accumulated in the elution tank, and to achieve effects such as stable ion elution from the electrode. .
[0060]
According to the configuration of claim 2 of the present invention, it is possible to prevent a decrease in the elution efficiency of ions eluted from the electrode due to the sludge accumulated in the elution tank, to perform stable ion elution from the electrode, and to the inside of the elution tank. It is possible to eliminate the need for deposit processing.
[0061]
According to the configuration of the third aspect of the present invention, it is possible to prevent a decrease in the elution efficiency of ions eluted from the electrode due to the sludge accumulated in the elution tank, to perform stable ion elution from the electrode, The sludge treatment can be made unnecessary.
[0062]
According to the configuration of the fourth aspect of the present invention, it is possible to save electricity while preventing unnecessary energization, and it is possible to prevent an electric shock during electrode maintenance.
[0063]
According to the configuration of the fifth aspect of the present invention, the elution tank can be inspected at the time of inspection in the processing tank, and the elution tank can be easily maintained through the inspection opening.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a sewage treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view seen from the other direction.
FIG. 3 is an enlarged sectional view of the elution tank.
FIG. 4 is a perspective view of the water splitting device.
FIG. 5 is an enlarged cross-sectional view of an elution tank according to another embodiment of the present invention.
[Explanation of symbols]
1 treatment tank 5 1st anaerobic part (anaerobic part)
8 Elution tank 9 Outlet
12 electrodes
22 Aerobic part
28 Settling part
49 First inspection opening (inspection opening)
50 First lid (lid)
55 Control circuit (control means)

Claims (5)

A treatment tank having an anaerobic part, an aerobic part and a sedimentation part, an elution tank having an electrode made of iron or aluminum and eluting iron ions or aluminum ions by energizing the electrode, and elution of sewage in the treatment tank A transfer means for supplying to the tank; and a discharge port provided in the elution tank for returning the sewage supplied to the elution tank to the treatment tank, the discharge port of the elution tank being located above the sewage in the treatment tank and an electrode A sewage treatment apparatus provided at a lower position. A treatment tank having an anaerobic part, an aerobic part and a sedimentation part, an elution tank having an electrode made of iron or aluminum and eluting iron ions or aluminum ions by energizing the electrode, and elution of sewage in the treatment tank A transfer means for supplying to the tank; and a discharge port provided in the elution tank for returning the sewage supplied to the elution tank to the treatment tank. The discharge port of the elution tank is located above the sewage in the treatment tank and is eluted. A sewage treatment apparatus provided at the bottom of a tank. A treatment tank having an anaerobic part, an aerobic part, and a precipitation part; an elution tank having an electrode made of iron or aluminum and having an inclined bottom part for energizing the electrode to elute iron ions or aluminum ions; and in the treatment tank And a discharge means for returning the sewage provided in the elution tank to the treatment tank, and the discharge port of the elution tank from the sewage in the treatment tank. A sewage treatment apparatus provided near the lowest position at the bottom of the elution tank. 4. The sewage treatment apparatus according to claim 1, further comprising a control unit that stops energization of the transfer unit and the electrode. The inspection tank in the upper part of the processing tank is provided with an inspection opening and a lid for closing the inspection opening so as to be openable and closable, and the elution tank is provided in the vicinity of the inspection opening. The sewage treatment apparatus according to claim 3.

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