JPH10263551A - Sewage treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewage treating device capable of judging the defect of a returning means without inspecting the sewage treating device. SOLUTION: Constant current is applied to an electrode 12 in a elution vessel 8 provided in a treating vessel 1 having an anaerobic part 5, an aerobic part 22 and a settling part 28, a returning means for returning the sewage in the treating vessel 1 through a discharge port 9 provided on the bottom of the elution vessel 8 to the anaerobic part 5 and a control means 57 for controlling an alarm means based on a detected value of the voltage between the electrodes 12 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sewage treatment apparatus for purifying sewage, and more particularly to a sewage treatment apparatus for removing phosphorus from sewage.

[0002]

2. Description of the Related Art A sewage treatment apparatus of this type is known, for example, from Japanese Patent Application Laid-Open No. 7-108296 (C02F 3/30). This sewage treatment device treats sewage in the aerobic tank,
It is returned to the anaerobic tank through an elution tank that has electrodes and elutes iron ions, and the iron ions eluted from the elution tank are reacted with orthophosphoric acid in sewage to aggregate and precipitate as a water-insoluble phosphorus compound. It removes phosphorus.

[0003] However, if the return means for supplying sewage from the elution tank to the anaerobic tank breaks down, the iron ions eluted from the elution tank are not supplied to the sewage in the sewage treatment apparatus until the next maintenance, so that phosphorus is removed. In addition to this, there is a drawback in that excessive iron ions are supplied to the sewage collected in the elution tank to waste electrodes and electricity.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and provides a sewage treatment apparatus capable of judging a failure of the return means without checking the sewage treatment apparatus. That is the task.

[0005]

A first means for solving the above-mentioned problems is to apply a current to a treatment tank having an anaerobic part, an aerobic part and a sedimentation part, and to apply an electric current to an electrode made of iron material or aluminum. An elution tank for eluting ions or aluminum ions, and return means for returning sewage in the treatment tank to the treatment tank via a discharge port provided in the elution tank; and A control means is provided above and below the electrodes, and a control means for detecting a voltage value between the electrodes and controlling an alarm means based on the detected voltage value is provided.

[0006] A second means for solving the above problems is as follows.
A treatment tank having an anaerobic part, an aerobic part and a sedimentation part, an elution tank for applying an electric current to an electrode made of iron or aluminum to elute iron ions or aluminum ions, and providing a wastewater in the treatment tank in the elution tank. Return means for returning to the treatment tank through the discharge port provided, the discharge port is provided above the sewage in the treatment tank and below the electrodes, and a voltage value between the electrodes is detected, and a predetermined value is detected. A control means for controlling the alarm means when the above voltage change is detected is provided.

In the first means or the second means, it is preferable that the control means stops a current supply means for applying a constant current to the electrode when detecting a voltage value equal to or higher than a predetermined voltage.

In the first means or the second means, when the control means detects a voltage value equal to or higher than a predetermined voltage, it is preferable to apply a voltage lower than the predetermined voltage to the electrode.

[0009] A third means for solving the above problems is as follows.
A treatment tank having an anaerobic part, an aerobic part and a sedimentation part, an elution tank for applying an electric current to an electrode made of iron or aluminum to elute iron ions or aluminum ions, and providing a wastewater in the treatment tank in the elution tank. Return means for returning to the treatment tank through the discharge port provided, the discharge port is provided above the sewage in the treatment tank and below the electrodes, the current value between the electrodes is detected, the detected current A current supply means for applying a current to the electrode based on the value is stopped, and a control means for controlling an alarm means is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail below based on a sewage treatment apparatus shown in FIGS.

Reference numeral 1 denotes a treatment tank buried underground. The inside of the processing tank 1 is divided into first anaerobic section 5, second anaerobic section 18, aerobic section 22, sedimentation section 28, and disinfecting section by a first partition 2, a second partition 3 and a third partition 4. It is divided into 30.

Reference numeral 5 denotes a first anaerobic section having an inflow port 6 into which miscellaneous wastewater flows, and reference numeral 7 denotes a first anaerobic filter disposed in the first anaerobic section 5, which flows into the first anaerobic section 5. Sedimentation and separation of the hardly decomposable impurities mixed in the wastewater, and the anaerobic microorganisms attached to the first anaerobic filter bed 7 anaerobically decompose the organic substances and convert the organic nitrogen into ammonia nitrogen. Anaerobic decomposition.

Reference numeral 8 denotes a rectangular box-shaped elution tank disposed above the sewage of the first anaerobic section 5 and at a position facing a first inspection opening 49, which will be described later. The treated water supplied from the water distribution measuring device 39 is returned to the first anaerobic section 5 through the third return pipe 45. Reference numeral 10 denotes an exhaust port provided above the elution tank 8 for discharging air from the elution tank 8.

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 an insulator for closing the elution tank 8. Reference numeral 13 denotes a power supply device which is controlled by a control circuit 57 to be described later and applies a DC constant current between the electrodes 12, and elutes from the electrode 12 by applying a DC constant current supplied from the power supply device 13 between the electrodes 12. The supplied iron ions are supplied into the elution tank 8. The elution tank 8, the electrodes 12 and the power supply device 13 constitute an elution device.

Reference numeral 14 denotes a first air diffuser disposed between the electrodes 12 at the bottom of the elution tank 8 and has a number of air outlets and is connected to the first blower 15. By discharging the supplied air from the air outlet, the electrode 12 is washed and sludge is prevented from adhering, and divalent iron ions eluted from the electrode 12 react with orthophosphoric acid.
Oxidizes to monovalent iron ions.

Reference numeral 16 denotes the first anaerobic part 5
The treated water decomposed anaerobically in the first anaerobic section 5 is supplied to a second anaerobic section 18 to be described later through a first water supply port 17 penetrating the upper part of the first partition wall 2 by an advection pipe.

Reference numeral 18 denotes a first anaerobic section 5 formed by the first partition wall 2.
The second anaerobic section 19 is a second anaerobic filter bed disposed in the second anaerobic section 18. The second anaerobic filter bed 19 captures suspended matter and removes organic matter by anaerobic microorganisms. It anaerobically decomposes organic nitrogen into ammonia nitrogen while anaerobically decomposing.

Reference numeral 20 denotes a second anaerobic section 18 provided in the second anaerobic section 18.
The treated water decomposed anaerobically in the second anaerobic section 18 is supplied to the aerobic section 22 to be described later through an advection pipe through a second water supply port 21 penetrating the upper part of the second partition wall 3. Reference numeral 22 denotes an aerobic section defined by the second partition wall 3 as a second anaerobic section 18.
The anaerobic treated water flows in through the second advection pipe 20. Reference numeral 23 denotes a contact material provided in the aerobic part 22, which promotes the culture of aerobic microorganisms.

Reference numeral 24 denotes a second air diffuser disposed at the bottom of the aerobic section 22. The second air diffuser forms a number of air outlets and is connected to the second blower 25 to supply air supplied from the second blower 25. The air is discharged from the air outlet to maintain the inside of the aerobic part 22 in an aerobic state, and the treated water is aerobically decomposed by aerobic microorganisms,
Ammonia nitrogen is decomposed into nitrate or nitrite nitrogen by the action of nitrate or nitrite.

Reference numeral 26 denotes a third air diffuser disposed below the contact member 23 and having a large number of air outlets.
Is connected to The air supply from the second blower 26 can be switched to either the second diffuser 24 or the third diffuser 26 by a first solenoid valve 27 controlled by a control circuit 57 described later.

The first solenoid valve 27 normally switches to the second diffuser 24 and discharges the air supplied from the second blower 25 from the air outlet of the second diffuser 24 so that the inside of the aerobic section 22 is improved. When the contact material 23 is cleaned, the air supply from the second blower 25 is switched to the third air diffuser 26 and the third air diffuser 26 is maintained.
Air is discharged from the air outlet of the biofilm, and the biofilm that has adhered to the contact material 23 and multiplied and gradually thickened is peeled off.

Reference numeral 28 denotes a sedimentation section which is separated from the aerobic part 22 by the third partition wall 4 and is provided at the bottom of the third partition wall 4 and flows in from a communication port 29 which communicates the aerobic part 22 and the sedimentation part 28. Then, the treated water aerobically decomposed in the aerobic part 22 is separated into a precipitate and a supernatant. Further, in order to return the sediment deposited on the bottom of the sedimentation part 28 to the aerobic part 22 from the communication port 29, the bottom part of the sedimentation part 28 is aerobic part.
It is inclined to 22 side.

Reference numeral 30 denotes a disinfecting section provided above the sedimentation section 28, through which the supernatant liquid separated in the sedimentation section 28 flows. Reference numeral 31 denotes a sterilizing device provided in the disinfecting unit 30, which disinfects the treated water flowing into the disinfecting unit 30 by a chlorine-based chemical or the like provided in the sterilizing device 31. 32 is the disinfection unit 30
The treated water that has been disinfected in the disinfecting section 30 is drained out of the treatment tank 1 through a drain port communicating with the treatment tank 1.

A first return pipe 33 communicates the bottom of the aerobic section 22 and the top of the first anaerobic section 5. Reference numeral 34 denotes a fourth air diffuser disposed in the first return pipe 33 at the bottom of the aerobic section 22. The fourth air diffuser forms a number of air outlets and is connected to the third blower 35.
By discharging the air supplied from the third blower 35 from the air outlet, the sludge deposited on the bottom of the aerobic part 22 and the sediment returned to the aerobic part 22 from the sedimentation part 28 are transferred to the first return pipe. The air is sucked into 33 and returned to the first anaerobic section 5.

Reference numeral 36 denotes a second return pipe which communicates the upper part of the sedimentation section 28 with an inflow chamber 40 of a water distribution measuring device 39 described later. Reference numeral 37 denotes a fifth air diffuser disposed in the second return pipe 36, which forms a number of air outlets and is connected to the third blower 35. The air supply from the third blower 35 can be switched to either the fourth diffuser 34 or the fifth diffuser 37 by a second solenoid valve 38 controlled by a control circuit 57 described later.

The second solenoid valve 38 normally switches 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, whereby the sedimentation section 28
The supernatant liquid therein is sucked into the second return pipe 36 and transferred to the inflow chamber 40 of the water distribution measuring device 39 described later.

After the contact material 23 has been washed, the air supply from the third blower 35 is switched to the fourth air diffuser 34 and the air is discharged from the air outlet of the fourth air diffuser 34 so that the aerobic part 22 is removed. The treated water in the first anaerobic section 5 passes through the first return pipe 33
Flows into. With this flow, the sludge deposited on the bottom of the aerobic part 22 and the sediment returned from the sedimentation part 28 to the aerobic part 22 are sucked into the first return pipe 33 and returned to the first anaerobic part 5.

Numeral 39 denotes a rectangular box-shaped water measuring device provided above the sedimentation section 28, and the amount of the supernatant liquid transferred by the second return pipe 36 to the elution tank 8 can be adjusted to a predetermined amount. It has become. The water metering device 39 includes an inflow chamber 40 connected to the second return pipe 36, an intermediate chamber 42 partitioned by a partition wall 41 having an opening communicating with the inflow chamber 40 and a lower side, and an intermediate chamber 42. It is divided into a first water separation chamber 43 and a second water separation chamber 44 into which the treated water flows.

The first water separation chamber 43 is connected to the elution tank 8 by a third return pipe.
45, and the upper part of the wall is
They communicate with each other through cutouts 46 which are open in a letter shape. The second
The water dividing chamber 44 communicates with the upper part of the aerobic part 22 by a pipe 47, and communicates with the intermediate chamber 42 by an opening formed at the upper part of an overflow weir plate 48 whose height can be adjusted.

The height of the overflow weir 48 is adjusted and the overflow weir 48 is adjusted.
The size of the opening formed in the upper part of the
By setting the amount of treated water to be returned to the aerobic section 22, the amount of treated water flowing into the elution tank 8 from the first water separation chamber 43 can be adjusted.

Reference numeral 49 denotes a first inspection opening provided at a position facing the first anaerobic section 5, the second anaerobic section 18 and the elution tank 8 above the first partition wall 2, and 50 denotes the first inspection opening. A reed switch provided in 49 detects the open / closed state by a magnet 52 provided in a first lid 51 that opens and closes the first inspection opening 49 so as to be openable and closable. The first lid 51
The first lid 51 is positioned by a positioning means (not shown) so that the magnet 52 provided on the first side faces the reed switch 50.

The first lid 51 removes the sludge deposited on the bottoms of the first anaerobic section 5 and the second anaerobic section 18 by suction and removes the electrode of the elution tank 8.
It opens and closes at the time of maintenance of 12, etc. When the first cover 51 is opened, the reed switch 50 is turned off, and based on this signal, the control circuit 57 stops only the power supply 13 and activates the power supply 13 when the first cover 51 is attached.

Reference numeral 53 denotes a second inspection opening provided at a position facing the aerobic portion 22, and reference numeral 54 denotes a second lid for closing and opening the second inspection opening 53 freely. Reference numeral 55 denotes a third inspection opening provided at a position facing the sterilization device 31, and reference numeral 56 denotes a third lid body that closes the third inspection opening 55 so as to be openable and closable. It opens and closes when refilling.

Reference numeral 57 denotes the first blower 15 and the second blower 2
5, third blower 35, power supply 13, first solenoid valve 27, second
This is a control circuit for controlling alarm means for notifying a user of an abnormal state of the electromagnetic valve 38 and the processing tank 1 by a buzzer, an LED, or the like.

The household wastewater discharged from the house flows into the first anaerobic section 5 through the inlet 6. The first anaerobic filter bed 7 disposed in the first anaerobic section 5 removes relatively coarse solids and contaminants such as toilet paper in household wastewater, and removes them in each treatment tank flowing in later. Preliminary treatment for smooth treatment is performed, and at the same time, the removed solids, contaminants, and sewage passing through the first anaerobic filter bed 7 are anaerobically decomposed by the action of anaerobic microorganisms, and the BOD is reduced. Sludge generated by the decomposition of the sewage accumulates at the bottom of the first anaerobic section 5. It also anaerobically decomposes organic nitrogen into ammonia nitrogen.

The treated water that has been anaerobically decomposed in the first anaerobic section 5 by the new domestic wastewater flowing into the first anaerobic section 5 is the first anaerobic section.
It flows into the second anaerobic section 18 from the first water supply port 17 of the advection pipe 16.
The treated water that has flowed into the second anaerobic section 18 anaerobically decomposes organic substances by the action of anaerobic microorganisms in the second anaerobic filter bed 19 to reduce BOD, and sludge generated by the decomposition of sewage is treated in the second anaerobic section. 18 Deposit on the bottom. It also anaerobically decomposes organic nitrogen into ammonia nitrogen.

The treated water anaerobically decomposed in the second anaerobic filter bed 19 by the new treated water flowing into the second anaerobic section 18 is supplied to the second advection pipe.
20 flows into the aerobic part 22 from the second water supply port 21. The treated water that has flowed into the aerobic part 22 is stirred by the air supplied from the second blower 25 being discharged from the air outlet of the second air diffuser 24.

Further, oxygen is dissolved in the treated water, and aerobic microorganisms attached to the surface of the contact material 23 decompose the treated water aerobically by the action of the aerobic microorganisms. Decomposes nitrogen into nitrate and nitrite nitrogen. Further, the sludge generated by the decomposition of the sewage accumulates on the bottom of the aerobic part 22.

The freshly treated water flowing into the aerobic part 22 causes treated water aerobicly decomposed by the action of the aerobic microorganisms attached to the contact material 23 to pass through the communication port 29 at the bottom of the aerobic part 22 to the sedimentation part.
Flow into 28. The treated water flowing into the sedimentation section 28
While rising inside, the sedimentable substance sinks and is returned to the aerobic part 22 from the communication port 29, and the supernatant flows into the disinfecting part 30. The supernatant liquid that has flowed into the disinfecting section 30 is disinfected by a disinfecting device 31 equipped with a chlorine-based chemical and kills bacteria such as pathogenic bacteria,
The water is drained out of the treatment tank 1 from the drain port 32.

The air supplied from the third blower 35 is
By discharging from the air outlet of the air diffuser 36, the sedimentation section
The supernatant liquid in 28 flows into the inflow chamber 40 of the water separation measuring device 39,
The water is rectified in the intermediate chamber 42 and flows into the first water separation chamber 43 and the second water separation chamber 44.

The height of the overflow weir plate 48 is adjusted, and the second water diversion chamber 44 is adjusted.
By changing the size of the opening formed above the overflow weir plate 48 that communicates with the intermediate chamber 42, the amount of water returned from the second water separation chamber 44 to the aerobic section 22 is determined. The amount of treated water flowing into the elution tank 8 from the water chamber 43 can be adjusted to a predetermined amount.

The treated water flowing into the elution tank 8 from the first water separation chamber 43 via the third return pipe 33 receives the iron eluted from the electrode 12 by applying a DC constant current between the electrodes 12 made of iron material. Ions are supplied. The eluted iron ions react with the orthophosphoric acid present in the elution tank 8, aggregate and precipitate as a water-insoluble phosphorus compound, and are returned from the outlet 9 to the first anaerobic section 5. The iron ions in the treated water returned to the first anaerobic section 5 react with orthophosphoric acid present in the first anaerobic section 5 and aggregate and precipitate as a water-insoluble phosphorus compound.

The nitrate or nitrite nitrogen in the treated water returned to the first anaerobic section 5 is reduced by the denitrifying bacteria present in the first anaerobic section 5 in a large amount, and diffused into the air as nitrogen gas. Removed.

The treated water returned from the elution tank 8 to the first anaerobic section 5 is supplied not from the aerobic section 22 where the dissolved oxygen concentration is extremely high but from the sedimentation section 28. Even if the treated water is returned to the first anaerobic section 5, anaerobic treatment can be performed with little influence on anaerobic microorganisms.

The biofilm formed by the aerobic microorganisms attached to the contact material 23 grows and gradually thickens. Therefore, the control circuit 57 controls the first solenoid valve 27 periodically to prevent clogging. The air supply from the second blower 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.

When the supply of air from the third air diffuser 26 is completed, the peeled biofilm is deposited on the bottom of the aerobic part 22, but the control circuit 57 controls the second solenoid valve 38 to transmit the air from the third blower 35. By switching the air supply to the fourth air diffuser 34 and discharging air from the air outlet of the fourth air diffuser 34, the treated water in the aerobic part 22 is supplied to the first anaerobic part 5 via the first return pipe. Flows into. With this flow, the sludge deposited at the bottom of the aerobic section 22 and the sediment returned from the sedimentation section 28 to the aerobic section 22 are returned to the first anaerobic section 5 via the first return pipe 33.

The elution tank 8 is disposed so as to face the first inspection opening 49. The first lid 51 is opened to open the first anaerobic section 5 and the second anaerobic section 5.
The elution tank 8 is used for removing sludge accumulated in the anaerobic part 18 by suction.
Can be checked. Further, when the first lid 51 is opened, the control circuit 57 stops only the power supply device 13 and continuously operates the devices other than the power supply device 13, so that the operation of the sewage treatment device and the sewage treatment status are confirmed. And electric shock during maintenance of the elution tank 8 can be prevented.

Since the sludge in the elution tank 8 is returned to the first anaerobic section 5 from the discharge port 9, it is not necessary to perform the sludge treatment in the elution tank 8.

Further, the hydrogen gas generated from the electrode 12 by the electrolysis of the electrode 12 is lighter than air, so that it is easy to accumulate in the upper part of the elution tank 8. Hydrogen gas from the first diffuser 14 to the elution tank 8
The gas is efficiently discharged to the outside of the elution tank 8 together with the air supplied thereto, and the hydrogen gas concentration in the elution tank 8 is prevented from increasing, thereby preventing the danger of explosion due to the hydrogen gas.

The third blower 35, the second solenoid valve 38, the fifth air diffuser 37, the second return pipe 36, the water distribution measuring device 39, the third return pipe 45, and the elution tank 8 remove sewage in the treatment tank 1. A return means for returning to the wastewater in the treatment tank 8 through the elution tank 8 is configured to remove phosphorus from the wastewater in the treatment tank 1. For example, a failure occurs in the third blower 35. In such a case, the return amount of sewage by the return means may decrease, or the sewage may not be returned.

In such a state, the amount of iron ions supplied to the sewage in the treatment tank 1 becomes insufficient, or iron ions cannot be supplied, and the phosphorus removal performance deteriorates.

According to the embodiment of the present invention, when the air supply amount is reduced due to the failure of the third blower 35, the amount of treated water supplied into the elution tank 8 by the return means is suddenly reduced, and the wastewater is discharged. Since the treated water is returned from the outlet 9 to the first anaerobic section 5, the level of the treated water accumulated in the elution tank 8 is lowered.

Therefore, since the volume of the electrode 12 immersed in the treated water is reduced, the electric resistance between the electrodes 12 increases, and the control circuit 57 controls the power supply device 13 to control the power supply device 13 so that a constant DC current flows through the electrode 12. Increase the voltage applied between 12 When the control circuit 57 detects this rapid voltage change, it controls the alarm means to notify the user. The user confirms this alarm and requests maintenance.

If the voltage after the voltage change is equal to or higher than 25 volts, the control circuit 57 controls the power supply device to prevent an electric shock or the like.
Stop 13 If the voltage after the voltage change is less than 25 volts, the current applied to the electrode 12 decreases until the maintenance is completed, and the phosphorus removing performance is reduced. Apply a constant voltage of less than volts. Even when the voltage after the voltage change is 25 volts or more, a configuration in which a constant voltage of less than 25 volts is applied to the electrode 12 may be adopted.

When the air supply from the third blower 35 is stopped due to the failure of the third blower 35, the electrodes 12 in the elution tank 8 are exposed, and the voltage between the electrodes 12 becomes 0 volt.

Accordingly, when the control circuit 57 detects this voltage, the power supply device 13 is stopped to save power, and the alarm means is controlled to notify the user. The user confirms this alarm and requests maintenance. In this case, the electrode 12
Since the current flowing therethrough is also 0 amperes, the control circuit 57 may stop the power supply device 13 by detecting the current value and control the alarm means to notify the user.

In the embodiment of the present invention, if the electrode 12 made of an iron material is immersed in the treatment water in the elution tank 8 for a long time, an oxide film is generated on the electrode surface, and the electrode 12 is in a passivated state, and The elution of ions gradually decreases, and the dephosphorization performance decreases.

Therefore, it is preferable to apply a constant DC current between a pair of electrodes made of an iron material and change the polarity of the current at predetermined time intervals. An oxide film is formed on the surface of the iron material on the anode side when used for a long period of time, but the surface of the iron material on the cathode side is cleaned by 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 formed on the iron material surface on the anode side and the elution of iron ions is reduced, and the phosphorus removal performance can be maintained. Can be kept constant.

In this configuration, since both electrodes are made of iron material, iron ions are always eluted from the iron material serving as the anode electrode and supplied to the treated water, so that the dephosphorization performance is always maintained at a constant state. can do.

It is also possible to adopt a configuration in which an iron material is used at least on the anode side of the electrodes, a DC constant current is applied between the two electrodes, and the applied current is increased in a pulsed manner at predetermined time intervals. In this configuration, by increasing the applied current in a pulsed manner, the oxide film generated on the surface of the iron material on the anode side can be peeled off, and the elution of iron ions is kept almost constant, and the dephosphorization performance is kept constant. Can be maintained.

Further, a constant DC current may be applied between a pair of electrodes made of an iron material, the polarity of the current may be changed at predetermined time intervals, and the applied current may be increased in a pulsed manner. If the time required for the polarity change is long, an oxide film is formed on the iron material surface on the anode side, and by changing the polarity, the oxide film can be washed and removed with a hydrogen gas. Some time is required until the oxide film is peeled off, and the electric resistance until the oxide film is peeled off is large, which may increase power consumption.

Therefore, the oxide film on the surface of the iron material converted from the anode to the cathode can be removed in a short time by increasing the applied current in a pulsed manner as described above, thereby preventing an increase in power consumption.

In the embodiment of the present invention, iron is used for both electrodes as an electrode for applying a DC constant current to elute iron ions. However, iron is used for the anode and titanium is used for the cathode. Alternatively, a configuration using an insoluble material such as platinum or platinum may be used.

In the embodiment of the present invention, an iron material is used for both electrodes as an electrode for eluting iron ions by applying a constant DC current, but a configuration using aluminum may be used.

[0065]

According to the configuration of the first aspect of the present invention, it is possible to easily determine the failure of the return means and to notify the user of the occurrence of the failure.

According to the structure of the second aspect of the present invention, effects such as prevention of electric shock can be obtained.

According to the configuration of the third aspect of the present invention, effects such as prevention of electric shock and suppression of deterioration of phosphorus removal performance can be obtained.

According to the configuration of claim 4 of the present invention, it is possible to easily determine the failure of the return means and to notify the user of the occurrence of the failure.

According to the configuration of claim 5 of the present invention, it is possible to easily determine the failure of the return means and to notify the user of the occurrence of the failure.

[Brief description of the drawings]

FIG. 1 is a sectional view of a sewage treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view as viewed from another direction.

FIG. 3 is an enlarged sectional view of the elution tank.

FIG. 4 is a perspective view of the same water measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing tank 5 1st anaerobic part (anaerobic part) 8 Elution tank 9 Outlet 12 Electrode 22 Aerobic part 28 Sedimentation part 57 Control circuit (control means)

Claims (5)

[Claims] 1. A treatment tank having an anaerobic part, an aerobic part and a sedimentation part, an elution tank for applying an electric current to an electrode made of iron material or aluminum to elute iron ions or aluminum ions, and a wastewater in the treatment tank Return means for returning to the treatment tank through a discharge port provided in the elution tank, the discharge port is provided above the sewage in the treatment tank and below the electrodes, and the voltage value between the electrodes is A sewage treatment apparatus comprising a control unit for detecting and controlling an alarm unit based on the detected voltage value. 2. A treatment tank having an anaerobic part, an aerobic part, and a sedimentation part, an elution tank for applying an electric current to an electrode made of iron or aluminum to elute iron ions or aluminum ions, and a wastewater in the treatment tank. Return means for returning to the treatment tank through a discharge port provided in the elution tank, the discharge port is provided above the sewage in the treatment tank and below the electrodes, and the voltage value between the electrodes is A sewage treatment apparatus comprising: a control unit that detects and detects a voltage change equal to or greater than a predetermined value and controls an alarm unit. 3. The apparatus according to claim 1, wherein said control means stops a current supply means for applying a constant current to said electrode when detecting a voltage value equal to or higher than a predetermined voltage.
A sewage treatment apparatus as described in the above. 4. The sewage treatment apparatus according to claim 1, wherein said control means applies a voltage lower than a predetermined voltage to said electrode when detecting a voltage value higher than a predetermined voltage. 5. A treatment tank having an anaerobic part, an aerobic part, and a sedimentation part, an elution tank for applying an electric current to an electrode made of iron or aluminum to elute iron ions or aluminum ions, and a wastewater in the treatment tank. And a return means for returning the wastewater to the treatment tank via a discharge port provided in the elution tank, wherein the discharge port is provided above the sewage in the treatment tank and below the electrodes, and a current value between the electrodes is detected. A sewage treatment apparatus characterized in that a current supply means for applying a current to the electrode based on the detected current value is stopped and a control means for controlling an alarm means is provided.