JP2001162281A - Water treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment apparatus capable of preventing excessive electrolysis when a user is absent for a long period of time to extend the life of electrodes and capable of preventing passivation to keep the constant capacity of the electrodes. SOLUTION: A dephosphorizing treatment apparatus P is equipped with an electrolytic cell 30, two sets of rectangular plate-shaped iron electrodes 31, 32 arranged in the electrolytic cell 30, the round rod-shaped passive electrode 39 arranged between the electrodes 31, 32, an electrode holder 33 for holding the electrodes 31, 32, 39 and a DC power supply for supplying an electrolytic current across the electrodes 31, 32, 39. An aeration pipe 35 for performing the aeration of the electrodes 31, 32 and a blower 36 disposed outside the cell to supply air to the aeration pipe 35 are arranged in the electrolytic cell 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water treatment apparatus,
More specifically, the present invention relates to a water treatment apparatus incorporated in a septic tank for treating human wastewater or domestic wastewater or a water tank for breeding organisms, and for removing phosphoric acid from water to be treated.

[0002]

2. Description of the Related Art Conventionally, as a water treatment apparatus of this type, two sets of iron electrodes which are incorporated in a septic tank or the like and electrolyze iron ions for removing phosphoric acid in water by electrolysis,
There is known a power source for supplying an electrolytic current to these electrodes, in which the polarity of two sets of iron electrodes is inverted (for example, Japanese Patent Application Laid-Open No. H11-128946).

[0003]

In such a water treatment apparatus, an electrolytic current is constantly applied in order to remove phosphorus and dissolve iron, so that a user of the septic tank needs to travel for a long time on a trip or a business trip. In the absence, the amount of water flowing into the septic tank is reduced, and an excessive electrolytic current is applied.

For this reason, electrolysis is stopped. However, when the operation is restarted, the electrode may be a passivating electrode, and there is a possibility that the phosphorus removal performance may not be maintained.

The present invention has been made in view of such circumstances, and when a user is absent for a long period of time, it is possible to prevent extra electrolysis and extend the life of an electrode.
An object of the present invention is to provide a water treatment apparatus that can prevent passivation and maintain constant performance of an electrode.

[0006]

According to the present invention, there is provided an electrolytic cell containing water to be treated, and an iron or aluminum ion disposed in the electrolytic cell for removing phosphoric acid in water. A set of three electrodes eluted by decomposition,
There is provided a water treatment apparatus comprising a DC power supply for supplying an electrolytic current to these electrodes.

[0007] The configuration of the three poles and one set of electrodes is intended to cause electrolysis by any two of the three poles, and one of the three poles is improper. It is intended to be a dynamic electrode and the remaining two to be an iron electrode or an aluminum electrode.

Here, examples of the passive electrode include an electrode made of silver, platinum, or the like, or an electrode obtained by coating an iron electrode or an aluminum electrode.

The remaining two electrodes are, for example, both iron electrodes or both aluminum electrodes.

[0010] If the control section reverses the polarity of the electrode, if desired, it is possible to prevent the formation of an iron oxide layer on the electrode surface, which may obstruct ion elution from the electrode.

The iron or aluminum ions eluted from the iron or aluminum electrode into the electrolytic cell are
Reacts with phosphoric acid (orthophosphoric acid) in water to form a poorly soluble phosphorus compound (Fe (OH) x (PO4) y or A
l (OH) x (PO4) y) and aggregate and precipitate.

[0012] The water treatment apparatus according to the present invention further comprises a control unit for electrolytically controlling a set of three electrodes, wherein the control unit controls one passive electrode as an anode electrode and the other two electrodes as an anode electrode. It is preferable to have an electrode cleaning mode in which electrolysis is performed as a cathode electrode and an electrode dissolving mode in which electrolysis is performed by inverting the polarity of the remaining two electrodes.

[0013] The electrode cleaning mode is a mode that is performed when the user is absent for a long time or the like. Electrolysis is performed by using one passive electrode as an anode electrode and the other two electrodes as cathode electrodes, so that a soluble electrode is applied. The surface is cleaned with generated hydrogen.

The electrode dissolution mode is a normal operation mode in which the polarity is reversed between two soluble electrodes and electrolysis is performed.

The water treatment apparatus according to the present invention further includes a water amount sensor for detecting an amount of water flowing into the water treatment apparatus, and controls when the amount of water detected by the water amount sensor becomes equal to or less than a predetermined value. Preferably, the unit is configured to automatically switch to the electrode cleaning mode. The fact that the water amount detected by the water amount sensor has become equal to or less than the predetermined value means that the user has been absent for a long period of time, and in this case, to maintain constant performance of the electrode.

[0016] In the water treatment apparatus according to the present invention, it is preferable that the control unit controls the electrolytic current value in the electrode cleaning mode to be smaller than the electrolytic current value in the electrode dissolving mode. With such control, an excessively large electrolytic current value can be reduced.

In the water treatment apparatus according to the present invention, it is preferable that the control unit periodically performs the electrode cleaning mode. For example, a timer is provided, and the timer is set so that several hours out of 24 hours are set to the electrode cleaning mode.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings together with modifications thereof. The present invention is not limited by these.

First Embodiment As shown in FIGS. 1 and 2, a dephosphorization treatment apparatus P as a water treatment apparatus according to a first embodiment of the present invention includes an inflow pipe 30a into which water to be treated flows and a treatment pipe 30a. An electrolytic cell 30 having a discharge pipe 30b for discharging the water from the outside to the outside, and two rectangular plate-shaped iron electrodes 31 and 32 arranged in the electrolytic cell 30
, A rod-shaped passive electrode 39 disposed between the electrodes 31 and 32, an electrode holder 33 for holding the electrodes 31, 32 and 39, and an electrolytic cell between the electrodes 31, 32 and 39. And a DC power supply for supplying an application current.

The electrolytic cell 30 is provided with an aeration tube 35 for aerating the electrodes 31 and 32 and a blower 36 outside the tank for supplying air to the aeration tube 35.

Further, as shown in FIGS.
An electrode unit 37 is formed by the electrodes 32 and 39 and the electrode holder 33, and as shown in FIGS. 1 and 2, a plate-shaped unit arrangement body 38 for disposing the electrode unit 37 at a predetermined position is an electrolytic cell. It is attached to the upper edge of 30.

As shown in FIGS. 6 and 7, the dephosphorization treatment apparatus P is incorporated in a small-sized combined treatment / purification tank D. The septic tank D is provided with a plurality of water purifying tanks from the side of the inflow pipe 2 into which mixed water of human wastewater and domestic wastewater flows to the side of the discharge pipe 3 for discharging treated water to the outside in accordance with the order of the water purification process. A septic tank main body 1 in which a tank is formed is provided.

Reference numeral 4 denotes a first anaerobic filter bed tank formed at the forefront of the inflow pipe 2 side. The first anaerobic filter bed tank 4 is provided with an anaerobic filter bed 5 which is a filter bed for anaerobic microorganisms.
Anaerobic treatment is performed by inhabiting microorganisms in the anaerobic filter bed 5. The anaerobic filter bed 5 suppresses the load of the next tank by preventing the sediment from being lifted up by the water flow when the inflow water or backwash wastewater temporarily flows in and becoming a suspended substance and flowing out to the next tank. Can be lowered.

Reference numeral 6 denotes a second anaerobic filter bed tank formed next to the first anaerobic filter bed tank 4. In the second anaerobic filter bed tank 6, anaerobic microorganisms are made to inhabit the anaerobic filter bed 7 to perform anaerobic treatment.

Reference numeral 8 denotes a next biofilm filtration tank formed adjacent to the second anaerobic filter bed tank 6. The biofilm filtration tank 8 is provided with an aerobic filter bed 9 which is a filter bed for aerobic microorganisms. The aerobic microorganisms inhabit the aerobic filter bed 9 to perform aerobic treatment. ing.

Reference numeral 10 denotes a next treated water tank formed adjacent to the biofilm filtration tank 8. In the treated water tank 10, the treated water that has been subjected to aerobic treatment in the biofilm filtration tank 8 and that has been filtered and advected is stored.

Numeral 11 denotes a disinfecting tank formed above the treated water tank 10. This disinfection tank 11 is usually
The supernatant water after the treatment is sterilized and discharged from the discharge pipe 3 to the outside.

The first anaerobic filter tank 4 and the second anaerobic filter tank 6 are separated by a vertical partition 12. At the upper part of the partition wall 12, an advection port 13 penetrating the partition wall 12 is formed. A rectangular or cylindrical advection tube 14 is fitted in the advection port 13.

The second anaerobic filter tank 6 and the next biofilm filter tank 8 are separated by an intermediate partition 15. An upflow passage 16 is fixedly provided on the second anaerobic filter bed tank 6 side of the intermediate partition wall 15. The water that has flowed from the first anaerobic filter bed tank 4 to the second anaerobic filter bed tank 6 through the convection tube 14 passes through the anaerobic filter bed 7 in a downward flow, and then rises through the upflow passage 16.

A metering pump 17 is provided above the upflow passage 16.
Is provided. The metering pump 17 is the second
A certain amount of water is transferred from the anaerobic filter tank 6 to the biofilm filter tank 8. That is, water is taken into the metering pump 17 from the water intake port 18 and sent to the next biofilm filtration tank 8 in a fixed amount.

In the anaerobic filter bed 7 in the second anaerobic filter bed tank 6,
Some suspended solids (SS) are captured. The trapped SS is gradually anaerobically decomposed and becomes soluble, or is stored as sludge at the bottom of the second anaerobic filter bed tank 6. In the anaerobic filter bed 7, organic nitrogen is anaerobically decomposed into ammonia nitrogen.

Near the bottom of the biofilm filtration tank 8,
2 are arranged in a horizontal state. The air diffuser tube 22 is connected to a blower 40, and performs an oxygen supply function for aerobic microorganisms living in the aerobic filter bed 9 of the biofilm filtration tank 8 by blowing out the air supplied by the blower 40.

A filter medium is disposed on the aerobic filter bed 9 in the biofilm filtration tank 8, and microorganisms adhering to the filter medium are collected by the BO.
The D component and the like are decomposed or made into SS, and captured in the filter medium. The biofilm filtration tank 8 also has a physical filtration action,
Here, SS is also captured. In the biofilm filtration tank 8,
The action of nitric acid bacteria and nitrites that convert nitrogen to nitric acid converts ammoniacal nitrogen to nitrate nitrogen.

A partition 23 is provided between the biofilm filtration tank 8 and the next treatment water tank 10. And this partition 23
A U-shaped pipe 24 is provided to connect the biofilm filtration tank 8 and the treatment water tank 10 through the water. The U-shaped tube 24 is bent at the upper part of the partition wall 23, and opens at a position near the bottom of the biofilm filtration tank 8 and a position near the bottom of the treated water tank 10.

From the upper part of the treated water tank 10, the first anaerobic filter bed tank 4
A circulation path 26 for constantly returning the supernatant water of the treated water is provided over the upper part of the water. An air lift pump 27 is connected to an end of the circulation path 26 above the treatment water tank 10. The air lift pump 27 has a treatment water tank 1
An air lift pipe 28 that pumps up the treated water of No. 0 is connected.

An end of the circulation path 26 above the first anaerobic filter tank 4 is formed as an inlet 29 to the first anaerobic filter tank 4. And near the inflow port 29 of the circulation path 26,
The phosphorus removal device P is connected to the circulation path 26.

In such a dephosphorization treatment apparatus P, when electrolysis is started, iron ions Fe ²⁺ are eluted from the electrodes 31 and 32 in the electrolytic cell 30, and oxygen is supplied into the treatment water by the aeration tube 35. .

The Fe ²⁺ is oxidized processed by dissolved oxygen becomes Fe ^3+, react orthophosphoric acid PO4 ^3- and water insoluble phosphorus iron salt Fe (OH) x (PO4) y
Becomes Then, the iron phosphate Fe (OH) x (P
O4) y is aggregated by using the SS component present in the water as a nucleus to form a large floc, a part of which floats in the water and another part precipitates and deposits on the bottom of the electrolytic cell 30.

The dephosphorization treatment device P is controlled by the control unit (not shown) of the septic tank D as follows. That is, the control by the control unit includes an electrode cleaning mode in which the passive electrode 39 is used as an anode electrode and the iron electrodes 31 and 32 are used as cathode electrodes, and an electrode dissolving mode in which the polarity of the iron electrodes 31 and 32 is inverted to perform electrolysis. Mode.

The electrode cleaning mode and the electrode dissolving mode are executed according to any one of the modes shown in FIGS.

First, as shown in FIG. 8, when the operation of the septic tank D is started, the dissolution mode is executed by a manual switching operation. This dissolution mode is a mode of normal operation, and is between two dissolvable electrodes, that is, iron electrodes 31 and 32.
The electrolysis is performed by reversing the polarity between them, and the dephosphorization of water to be treated is advanced.

Next, after a lapse of a predetermined time or before the user is absent for a long time, the cleaning mode is executed by a manual switching operation. In this cleaning mode, the passive electrode 39 is used.
Is used as an anode electrode and the iron electrodes 31 and 32 are used as cathode electrodes to perform electrolysis, and the surface of the iron electrodes 31 and 32 is washed with hydrogen generated on the iron electrodes 31 and 32.

As shown in FIG. 9, when the septic tank D is provided with a timer, by setting the timer, the control unit periodically performs the electrode cleaning mode. That is, when the dissolution mode is being executed, the dissolution mode continuation time T1 is determined by the timer. Then, it is compared whether T1 is smaller than a set time (for example, 20 hours).

If T1 is equal to or less than the set time, the dissolution mode is continued. If T1 is greater than the set time,
The mode is switched to the cleaning mode.

Then, when the cleaning mode is being executed, the cleaning mode continuation time T2 is determined by the timer.
Then, it is compared whether T2 is smaller than a set time (for example, 4 hours).

If T2 is equal to or smaller than the set time, the cleaning mode is continued. If T2 is greater than the set time,
Reset and switch to lysis mode.

As shown in FIG. 10, when the septic tank D is provided with an inflow amount sensor as a water amount sensor for detecting the amount of inflow water, when the dissolution mode is executed, the inflow amount The inflow amount V1 of water into the septic tank D is determined by the sensor.

V1 is the set inflow amount (for example, 250
If the flow rate is equal to or less than the set flow rate, the mode is switched to the cleaning mode. When V1 is larger than the set inflow amount, the dissolution mode is continued as it is.

In each of the embodiments shown in FIGS. 8 to 10, the control unit controls the electrolytic current value in the electrode cleaning mode to be smaller than the electrolytic current value in the electrode dissolving mode.

Second Embodiment As shown in FIGS. 11 to 12, a dephosphorization treatment device Q as a water treatment device according to a second embodiment of the present invention is a water storage device for storing water in a water tank 50 for breeding organisms. A storage tank 51, and two thick round bar-shaped iron electrodes 52.5 arranged in the water storage tank 51.
3, one thin round rod-shaped passivation electrode 54 arranged at a position substantially equidistant from these electrodes 52, 53, and an electrode holder 55 for holding these electrodes 52, 53, 54
And a DC power supply for supplying an electrolytic current between the electrodes 52, 53 and 54.

An air pipe 56 for aerating the electrodes 52 and 53 is provided in the water storage tank 51, and a blower 57 for supplying air to the aeration pipe 56 is provided next to the water storage tank 51. Have been.

As shown in FIGS. 13 to 15, the electrodes 52, 53, and 54 and the electrode holder 55 form the electrode unit 5.
As shown in FIGS. 11 and 12, a flat unit arrangement body 59 for arranging the electrode unit 58 at a predetermined position is attached to the upper edge of the water storage tank 51.

11 and 12, reference numeral 60 denotes a filtration tank provided downstream of the water storage tank 51, and 61 denotes a filtration tank 60.
A decolorizing tank 62 provided downstream of the decolorizing tank 61; a return pipe 64 provided through the inner lid 63 downstream of the decolorizing tank 61;
Represents an outer lid covered on the edge of the end wall of the inner lid 63.

The water tank 50 is formed of a box having a substantially rectangular planar shape. The water in the water tank 50 is pumped by the circulation pump 65 from the strainer 66 to the water storage tank 51 via the suction pipe 67.

In the water storage tank 51, phosphoric acid in water is removed. That is, iron ions Fe ²⁺ for removing phosphoric acid in water are eluted from the iron electrodes 52 and 53 by the electrolysis. Further, oxygen is supplied from the aeration tube 56 into the water.

Fe ²⁺ is oxidized by dissolved oxygen to form Fe ³⁺ , and reacts with orthophosphoric acid PO4 ^{3- in} water to form a colored hardly soluble iron phosphate Fe (OH) x (PO
4) It becomes y. And this iron phosphate salt Fe (OH)
x (PO4) y is agglomerated with the SS component existing in the water as a nucleus and forms a large floc, a part of which floats in the water, and the other part precipitates and deposits on the bottom of the water storage tank 51. .

The filtration tank 60 is for removing the iron phosphate Fe (OH) x (PO4) y floating in the water and the organic matter such as manure and residual food of the fish and shellfish, and has a built-in filter. I have.

The decolorization tank 61 introduces water that has passed through the filter of the filtration tank 60 from the bottom advancing port 60a, and the colored iron phosphate Fe (OH) x (PO4) floating in the water.
This is for decolorizing and filtering y, and has a built-in filter.

The return pipe 62 is supplied with water that has been purified by passing through the decolorization tank 61 and overflowed from the upper edge advection port 61a.
It is for returning to.

In FIG. 11, reference numeral 68 denotes a gravel layer disposed at the bottom of the water tank 50. In FIG. 12, reference numeral 69 denotes a control unit. The control unit 69 includes a blower 57 and a circulation pump 65.
And the electrolysis in the water storage tank 51 is controlled.

The control of the electrolysis in the water storage tank 51 performed by the control unit 69 includes, for example, the control of the electrolysis in the dephosphorization treatment apparatus P of the first embodiment—the execution of the electrode dissolving mode and the electrode cleaning mode— There are substantially the same.

Therefore, substantially the same control as in the embodiments of FIGS. 8 to 10 can be performed.

[0063]

According to the water treatment apparatus of the first aspect,
An electrolytic cell containing water to be treated, a set of three electrodes disposed in the electrolytic cell and eluting by electrolysis iron or aluminum ions for removing phosphoric acid in the water, and these electrodes And a DC power supply for supplying a current for electrolysis. Therefore, by causing electrolysis using any two of the three electrodes, when the user is absent for a long period of time, extra electrolysis can be prevented and the life of the electrode can be extended, and passivation can be achieved. Thus, the electrode can maintain a constant performance.

In the water treatment apparatus according to claim 2, 3
One of the pole pairs is a passive electrode and the other two are iron or aluminum electrodes. Therefore, by the control unit inverting the polarity of the electrode as desired,
It is possible to prevent the formation of an iron oxide layer on the surface of the electrode, which may hinder ion elution from the electrode, and to more reliably obtain the effect of the invention according to claim 1. Can be.

In the water treatment apparatus according to claim 3,
An electrode cleaning mode in which electrolysis is performed using one passive electrode as an anode electrode and the remaining two electrodes as a cathode electrode; An electrode dissolution mode in which two electrodes are subjected to electrolysis by inverting the polarity. Therefore, by appropriately switching between the electrode cleaning mode and the electrode dissolving mode by the control unit, it is possible to more reliably obtain the effect of the first aspect.

The water treatment apparatus according to claim 4 further comprises a water amount sensor for detecting an amount of water flowing into the water treatment apparatus, and the amount of water detected by the water amount sensor becomes equal to or less than a predetermined value. The control unit is configured to automatically switch to the electrode cleaning mode when the operation is started. Therefore, it is possible to estimate the long-term absence of the user from the amount of water detected by the water amount sensor, and in that case, by performing appropriate control, the effect of the invention according to claim 3 can be more reliably achieved. Obtainable.

In the water treatment apparatus according to the fifth aspect, the control unit controls the electrolytic current value in the electrode cleaning mode to be smaller than the electrolytic current value in the electrode dissolving mode. Therefore, by such control, it is possible to reduce an excessively large electrolytic current value, and it is possible to more reliably obtain the effect of the invention described in claim 3.

[0068] In the water treatment apparatus according to claim 6, the control section periodically performs the electrode cleaning mode. Therefore,
By such control, it becomes possible to perform the electrolysis while preventing the passivation more efficiently, and it is possible to more reliably obtain the effect of the invention according to claim 3.

[Brief description of the drawings]

FIG. 1 is a vertical longitudinal sectional view of a water treatment apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a plan view of the water treatment apparatus of FIG.

FIG. 3 is a front view of an electrode unit constituting the water treatment apparatus of FIG.

FIG. 4 is a plan view of the electrode unit of FIG. 3;

FIG. 5 is a side view of the electrode unit of FIG. 3;

FIG. 6 is a front sectional view of a small-sized combined treatment septic tank in which the water treatment apparatus of FIG. 1 is incorporated.

FIG. 7 is a plan view of the combined treatment septic tank of FIG. 6;

FIG. 8 is a flowchart showing one control method for a water treatment device in the combined treatment septic tank of FIG. 6;

FIG. 9 is a flowchart showing another control method for the water treatment device in the combined treatment septic tank of FIG. 6;

10 is a flowchart showing yet another control method for the water treatment apparatus in the combined treatment septic tank of FIG.

FIG. 11 is a front cross-sectional view of a water tank for breeding organisms in which a water treatment device according to Embodiment 2 of the present invention is incorporated.

FIG. 12 is a plan view of the water tank of FIG. 11;

FIG. 13 is a plan view of an electrode unit included in the water treatment apparatus of FIG.

FIG. 14 is a front sectional view of the electrode unit of FIG. 13;

FIG. 15 is a bottom view of the electrode unit of FIG.

[Explanation of symbols]

 D Septic tank P Dephosphorization treatment device 30 Electrolysis tank 31 Iron electrode 32 Iron electrode 33 Electrode holder 35 Aeration tube 36 Blower 37 Electrode unit 38 Unit arrangement 39 Passive electrode Q Dephosphorization treatment device 50 Water tank 51 Water storage tank 52 Iron electrode 53 Iron electrode 54 Passive electrode 55 Electrode holder 56 Aerated tube 57 Blower 58 Electrode unit 59 Unit arrangement 69 Control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C25B 9/00 Z F Term (Reference) 4D038 AA05 AA08 AB46 AB47 BA02 BA04 BA06 BB10 BB17 BB18 BB19 BB20 4D061 DA06 DA08 DB18 EA07 EB05 EB20 EB27 EB28 EB33 EB37 EB39 ED06 ED20 FA13 FA15 GA02 GC11 GC12 GC16 GC20 4K021 AA09 AB21 AB25 BB03 BC09 CA06 DA11 DA13 DC15

Claims (6)

[Claims] An electrolytic cell for storing water to be treated, and a set of three electrodes disposed in the electrolytic cell for eluting iron ions or aluminum ions for removing phosphoric acid in water by electrolysis. And a DC power supply for supplying an electrolytic current to these electrodes. 2. The water treatment apparatus according to claim 1, wherein one of a set of three electrodes is a passive electrode and the other two are iron electrodes or aluminum electrodes. 3. A control unit for controlling electrolysis of a set of three electrodes, wherein the control unit controls the electrolysis by using one passive electrode as an anode electrode and the remaining two electrodes as cathode electrodes. 2. The water treatment apparatus according to claim 1, comprising a cleaning mode and an electrode dissolving mode in which the polarity of the remaining two electrodes is reversed to perform electrolysis. 4. A water amount sensor for detecting an amount of water flowing into the water treatment apparatus, wherein the controller automatically cleans the electrode when the amount of water detected by the water amount sensor falls below a predetermined value. The water treatment apparatus according to claim 3, wherein the mode is switched to a mode. 5. The water treatment apparatus according to claim 3, wherein the control unit controls the electrolytic current value in the electrode cleaning mode to be smaller than the electrolytic current value in the electrode dissolving mode. 6. The water treatment apparatus according to claim 3, wherein the control unit periodically performs the electrode cleaning mode.