JPH11267683A - Treating device of waste water containing phosphate ions - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a denitrifying action through four seasons and to enhance efficiency of denitrification. SOLUTION: This device is provided with a waste water treating room having an inflow port of waste water and an outflow port, at least one pair of electrodes 5, 6 arranged to face each other at least one portion of which is immersed into the waste water in the treating room and incorporating iron and/or aluminum in at least one of them, and an electric power source with which power is supplied to the electrodes. A carrier 9 being a denitrifying means is provided in the vicinity of the one pair of confronting electrodes 5, 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating domestic wastewater containing phosphate ions, such as wastewater, especially domestic wastewater or apartment house wastewater.

[0002]

It is well known that one of the causes of eutrophication of rivers and lakes is the presence of phosphorus compounds. In addition, although this phosphorus compound is present in a large amount in household wastewater, it is difficult to purify it, and at present, no effective countermeasure can be taken.

Various treatment apparatuses for phosphorus compounds have been proposed. For household wastewater, an electrolytic elution method of iron is known (JP-A-3-89998, C02F 3/1).
2). In this technique, lyon phosphate in waste water is reacted with iron ions to form water-insoluble salts such as FePO ₄ and Fe (O
H) _x (PO ₄ ) This is a technique in which coagulation and precipitation are performed as _x (PO ₄ ) _y to remove iron ions in the wastewater by energizing an iron electrode installed in an electrolytic cell. The sewage treatment apparatus using the electric field elution method includes, for example, an anaerobic tank, an aerobic tank, and a treated water tank. Some are configured to circulate in the tank.

[0004]

In the anaerobic tank, since denitrifying bacteria that exist only in the anaerobic tank inhabit, nitrate ions and nitrite ions in the circulated sewage are reduced to nitrogen gas. Nitrogen is removed from sewage.

However, in winter, there is a problem that the activity of the denitrifying bacteria is reduced, so that the denitrification action is reduced.

[0006] In view of the above circumstances, an object of the present invention is to provide a phosphate ion-containing wastewater treatment apparatus capable of stabilizing denitrification throughout the four seasons and improving the efficiency of nitrogen removal.

[0007]

According to the present invention, there is provided an apparatus for treating wastewater containing phosphate ions, comprising a wastewater treatment chamber having an inlet and an outlet for wastewater, wherein at least a part of the wastewater is immersed in the wastewater in the treatment chamber. A wastewater treatment device comprising at least one pair of electrodes, at least one of which includes iron and / or aluminum, and a power supply for supplying electricity to the electrodes, wherein the wastewater treatment device is in the vicinity of the pair of opposed electrodes. Is provided with denitrification means.

The apparatus for treating a phosphate ion-containing waste water according to the present invention comprises: a waste water treatment chamber having an inlet and an outlet for waste water;
Drainage comprising at least one pair of electrodes including at least one pair of electrodes containing iron and / or aluminum and at least one pair of electrodes including iron and / or aluminum, and a power supply for supplying electricity to the electrodes, the drainage being disposed so as to be at least partially immersed in the wastewater in the treatment chamber. Wherein the other electrode of the pair of opposed electrodes is an insoluble electrode covered with a carrier in which microorganisms easily exist.

Further, the apparatus for treating a phosphate ion-containing wastewater of the present invention is disposed so as to face a wastewater treatment chamber having an inlet and an outlet for the wastewater so that at least a part of the wastewater is immersed in the wastewater in the treatment chamber. A wastewater treatment apparatus, wherein one electrode includes at least a pair of electrodes containing iron and / or aluminum, and a power supply for energizing the electrodes, wherein the other electrode of the pair of electrodes facing each other Are characterized by comprising a soluble electrode containing iron and / or aluminum and an insoluble electrode covered with a carrier in which microorganisms are likely to exist.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a wastewater treatment apparatus according to the present invention.

FIG. 1 is an explanatory view showing an embodiment of the apparatus for treating wastewater containing phosphate ions of the present invention, FIG. 2 is a partially exploded perspective view of an electrode unit, FIG. 3 is an enlarged view of the apparatus shown in FIG. FIG. 4 is an explanatory view showing another embodiment of the apparatus for treating phosphate ion-containing wastewater of the present invention, and FIG. 5 is an explanatory view of polarity reversal.

The treatment apparatus of the present invention is used, for example, in a wastewater treatment apparatus such as a combined septic tank. Figure 1 shows the merged septic tank.
As shown in the figure, a first anaerobic filter tank A and a second anaerobic filter tank B
, A biological filtration tank C, a treatment water tank D, and a disinfection tank E. The water flows into the first anaerobic filter bed tank A, and the wastewater is treated in each tank, and then discharged from the disinfection tank E. ing.
Then, the processing apparatus 1 sends the air pump F
Is disposed in the circulation path L for returning the treated water pumped to the first anaerobic filter bed tank A.

As shown in FIG. 1, the treatment apparatus 1 has a wastewater treatment chamber 4 having a wastewater inlet 2 and a wastewater outlet 3, and at least a part of the wastewater is immersed in the wastewater in the treatment chamber 4. A pair of electrodes 5 and 6 arranged opposite to each other;
A power supply 7 for supplying electricity to the power supply 6 and an air aeration device 8 for supplying air to the wastewater in the wastewater treatment chamber 4 are provided.

The electrode 5 is a dissolvable electrode that can be manufactured from a source of iron and / or aluminum ions such as iron, iron alloys, aluminum, aluminum alloys or iron-aluminum alloys. On the other hand, the electrode 6 is an insoluble electrode that can be manufactured from an insoluble metal, such as platinum, gold, titanium, or carbon.

In the present embodiment, of the electrodes 5 and 6, the electrode 5 is an electrode on the anode (anode) side, and the electrode 6 is an electrode on the cathode (cathode) side. When the electrode 5 is made of iron, the iron ions eluted from the electrode 5 undergo an agglutination reaction with phosphate ions and hydroxide ions contained in the wastewater to generate iron phosphate and iron hydroxide. On the other hand, the electrode 6 becomes anaerobic by the reduction reaction. Therefore, as shown in FIG. 2, the electrode 6 is covered with a carrier 9, which is a denitrifying means, in which microorganisms are likely to exist, so that denitrifying bacteria can inhabit. This allows
The denitrification action can be caused not only in the first anaerobic filter tank A but also in the wastewater treatment chamber 4.

The denitrification means is not particularly limited in the present embodiment as long as it is a carrier on which microorganisms are likely to exist. For example, a porous sponge made of a resin or a ceramic made of a sintered body is used. Etc. can be used.

Electrodes 5 and 6 arranged in the wastewater treatment chamber 4
As shown in FIGS. 2 and 3, four sets of electrode units 12 housed in the partition case 10 at predetermined intervals with the handle 11 therebetween are incorporated in the wastewater treatment chamber 4 by, for example, partition rods 13. be able to. A terminal 14 is fixed to the electrodes 5 and 6 by screwing or soldering, and a lead wire 15 drawn from the terminal 14 is connected to a connector 16. The partition case 10 has an inflow port 10a and an outflow port 10a for drainage.
b is formed, and an air inlet 10c is formed.

The wastewater in the combined septic tank according to the present embodiment circulates through the treatment device 1 to remove nitrogen and phosphorus. The water entering the inlet is mainly composed of phosphate ions, nitrate ions, nitrite ions, and the like, and the phosphate ions coagulate with iron ions and / or aluminum ions eluted from the electrodes 5 in the wastewater treatment chamber 4. React, 1st
The effluent is discharged to the anaerobic filter bed layer A, and the aggregate is captured in the first and second anaerobic filter tanks A and B and the biological filtration tank C. Also,
Nitrate ions and nitrite ions are changed to nitrogen by the denitrifying bacteria generated in the carrier 9 of the cathode electrode 6 in the wastewater treatment chamber 4, and nitrate ions and the like which have not changed are subjected to the first and second anaerobic reactions. It changes to nitrogen in filter bed tanks A and B.

The air aeration device 8 has a porous diffuser pipe 17 or a diffuser plate installed at the center of the bottom of the wastewater treatment chamber 4 and a not-shown air for sucking compressed air into the diffuser pipe 17. And an air pump.
And the air pump are connected by a pipe 19.

In the present embodiment, the electrode on the side of the cathode is covered with a carrier in which microorganisms are likely to exist. However, the present invention is not limited to this. For example, as shown in FIG. 4, the cathode side electrode may be composed of a soluble electrode 20 containing iron and / or aluminum, and an insoluble electrode 21 such as platinum covered with the carrier 9. Also for each of the electrodes 20 and 21, the lead wire 15 drawn from the fixed terminal 14 is connected to the connector 16. However, in the present embodiment, the polarity of the electrodes 5 and 20 is applied to the power source 7 as shown in FIG. Polarity converter 2 for switching at predetermined time intervals
2 are connected to perform polarity inversion. For this reason, when the insoluble electrode 21 side becomes the anode due to the polarity reversal, the vicinity of the electrode 21 becomes oxidized and the denitrifying bacteria cannot inhabit. Is turned off (OFF), and control is performed so that only the insoluble electrode 21 does not flow current.

If the polarity reversal time is less than 30 minutes, the elution efficiency is reduced, so that the polarity reversal time can be 30 minutes or more, for example, 2 hours.

As the electrolytic elution method of iron (aluminum), a conventionally known method can be employed, and energization of the electrode may be continuous, intermittent, or pulsed. The amount of electricity varies depending on the concentration of phosphoric acid and other ions, the flow rate of wastewater, and the like, but the ratio of the concentration of iron ions and / or aluminum ions in the wastewater to the concentration of phosphorus (hereinafter abbreviated as “Fe / P”) is 0. .8-3.
It may be adjusted to be 0, preferably 1.0 to 2.5.

For example, Fe / P = 1 to 2.
In the case of 5, the phosphorus concentration in the wastewater on the inflow side is 5 mg /
And the flow rate is 1 liter / min.
The electrolysis current is controlled to 0.5-1.3A.

In the present invention, the treatment of iron (aluminum) in the wastewater containing phosphate ions by the electrolytic elution method is performed by reacting the iron ions (aluminum ions) eluted from the electrode with the phosphate ions in the wastewater to form a water-insoluble phosphorus. It utilizes a reaction (reaction A) to form a salt between an acid and iron (aluminum), but hydroxide ions are present in the wastewater, and the eluted iron ions (aluminum ions) It also reacts with ions (reaction B). Since reaction B is faster than reaction A, it is necessary to increase the amount of current to increase the outflow of iron ions (aluminum ions) in order to capture phosphate ions.

However, when calcium ions or magnesium ions are present in the waste water, those ions react with hydroxide ions (reaction D). This reaction D
Has a higher priority than the reaction B between the iron ion (aluminum ion) and the hydroxide ion, the reaction B is suppressed, and the iron ion (aluminum ion) is effectively used for the reaction A with the phosphate ion. Furthermore, calcium ions and magnesium ions also react with phosphate ions to form water-insoluble salts, which contributes to phosphate ion removal.

For this reason, in the present invention, calcium ion or magnesium ion is added to suppress the reaction B between iron ion (aluminum ion) and hydroxide ion, and to reduce the reaction A between iron ion (aluminum ion) and phosphate ion.
Can be performed efficiently. As a result, the amount of electricity can be reduced, power can be saved, and the elution amount of iron and aluminum can be reduced.

As described above, the wastewater treatment apparatus of the present invention can be used particularly advantageously for general household wastewater. Therefore, it may be used alone, but it may be combined with other purification systems, for example, activated sludge method, membrane separation method, anaerobic / aerobic circulation method, etc., to form a comprehensive wastewater purification system for homes and apartment houses. it can. It can also be used for large-scale processing systems (human waste processing plants).

[0028]

As described above, according to the present invention, in summer, the nitrogen removal rate when the carrier is installed on the cathode electrode is increased by about 30% when the carrier is not installed. In addition, nitrogen removal in winter is almost the same as that in the absence of a cathode electrode in summer. As a result, the denitrification effect can be stabilized throughout the four seasons, and the efficiency of nitrogen removal can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a treatment apparatus for treating wastewater containing phosphate ions according to the present invention.

FIG. 2 is a partially exploded perspective view of an electrode unit.

FIG. 3 is an enlarged view of the processing device in FIG. 1;

FIG. 4 is an explanatory view showing another embodiment of the apparatus for treating wastewater containing phosphate ions of the present invention.

FIG. 5 is an explanatory diagram of polarity reversal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Inflow port 3 Outflow port 4 Wastewater treatment chamber 5, 6, 20, 21 Electrode 7 Power supply 8 Air aeration apparatus 9 Carrier 12 Electrode unit

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 3/00 C02F 1/46 102 3/34 101

Claims (3)

[Claims] 1. A wastewater treatment chamber having an inlet and an outlet for wastewater, and disposed opposite to each other so that at least a part of the wastewater is immersed in the wastewater in the treatment chamber, at least one of which is iron and / or iron.
Or a wastewater treatment device comprising at least a pair of electrodes containing aluminum and a power supply for supplying a current to the electrodes, wherein the device contains a phosphate ion in which denitrification means is provided near the pair of electrodes facing each other. Wastewater treatment equipment. 2. A wastewater treatment chamber having a wastewater inlet and a wastewater outlet, and disposed opposite to each other so that at least a part of the wastewater is immersed in the wastewater in the wastewater treatment chamber, and one electrode is made of iron and / or aluminum. A wastewater treatment apparatus comprising at least a pair of electrodes and a power supply for supplying electricity to the electrodes, wherein the other electrode of the pair of electrodes facing each other is covered with a carrier in which microorganisms are likely to be present. An equipment for treating phosphate ion-containing wastewater as an electrode. 3. A wastewater treatment chamber having a wastewater inlet and a wastewater outlet, and disposed opposite to each other so that at least a part of the wastewater is immersed in the wastewater in the wastewater treatment chamber, and one electrode is made of iron and / or aluminum. A wastewater treatment apparatus comprising at least one pair of electrodes including a power source for supplying electricity to the electrodes, wherein the other electrode of the pair of opposed electrodes includes a soluble electrode containing iron and / or aluminum. And an insoluble electrode covered with a carrier in which microorganisms are likely to be present.