JP3982881B2 - Treatment apparatus and treatment method for waste water containing phosphate ions - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a treatment apparatus and a treatment method for domestic wastewater containing phosphate ions such as wastewater, particularly domestic wastewater or apartment house wastewater.
[0002]
[Prior art]
It is well known that the presence of phosphorus compounds is one of the causes of eutrophication of rivers and lakes. Moreover, although this phosphorus compound exists abundantly in the domestic household wastewater, the present condition is that the purification process is difficult and an effective measure cannot be taken.
[0003]
Various treatment apparatuses for phosphorus compounds have been proposed, but an iron electrolysis method is known for domestic wastewater (Japanese Patent Laid-Open No. 3-89998). This technique is a technique in which phosphate ions in waste water are reacted with iron ions to coagulate and remove them as water-insoluble salts such as FePO ₄ and Fe (OH) _x (PO ₄ ) _y. An iron electrode installed inside is energized to elute iron ions into the waste water. And as a sewage treatment apparatus using such an electric field elution method, for example, an anaerobic tank, an aerobic tank, and a treated water tank, the sewage in the treated water tank is passed through a treatment apparatus that elutes iron ions that react with phosphoric acid, Some are configured to be returned to an anaerobic tank.
[0004]
[Problems to be solved by the invention]
Among the electrodes installed in the electrolytic cell, the anode-side electrode elutes iron ions when energized, so that the thickness and width of the electrode gradually decrease. The degree of decrease in the electrode thickness (elution amount) is such that the electrolysis surface between the electrodes arranged facing each other is large, and the opposite side (back surface) of the electrode electrolysis surface is small. Decrease from the side, causing electrode sticking early. When such electrode slippage occurs, the distance between the anode-side electrode and the cathode-side electrode increases, and when a constant current is passed through the electrode, the voltage increases and the power consumption increases.
[0005]
An object of this invention is to provide the processing apparatus and the processing method of the phosphate ion containing waste water which can reduce power consumption by dissolving both surfaces of an electrode in view of the above situation.
[0006]
[Means for Solving the Problems]
Processor phosphate ion-containing waste water of the present invention, a waste water treatment chamber having an inlet and an outlet of the drain, at least part of which is arranged to dip in the waste water of the processing chamber, iron ions and / Or a wastewater treatment apparatus comprising an electrode including an aluminum ion generation source and a power source for energizing the electrode, wherein at least two pairs of electrodes are disposed , and adjacent electrodes of each electrode pair A configuration in which the polarity is the same polarity and one electrode in each electrode pair is an anode and the other electrode is a cathode, and the polarity of adjacent electrodes in each electrode pair is the same polarity and one electrode in each electrode pair is A configuration in which the other electrode is an anode and the other electrode is an anode, and a configuration in which the polarity of the adjacent electrodes of each electrode pair is different by making one of the adjacent electrodes of each electrode pair an anode and the other a cathode , For each electrode pair Constitutes the to different pole polarity of adjacent electrodes of each electrode pair, characterized in that it comprises a polarity converter repeating by the anode and the other as well as to the cathode one electrode fit Ri.
[0007]
Further, the apparatus for treating wastewater containing phosphate ions of the present invention uses an electrode containing iron ions and / or aluminum ions to electrochemically elute iron ions and / or aluminum ions into wastewater containing phosphate ions. A wastewater treatment method for coagulating and precipitating acid ions in the form of an insoluble salt with iron and / or aluminum, wherein at least two pairs of electrodes are disposed in the wastewater, and the polarity of the adjacent electrodes of each electrode pair is determined. A configuration in which one electrode in each electrode pair is an anode and the other electrode is a cathode, and the polarity of adjacent electrodes in each electrode pair is the same polarity, and one electrode in each electrode pair is a cathode In addition, the polarity of the adjacent electrode of each electrode pair by making the other electrode an anode and making one of the adjacent electrodes of each electrode pair an anode and the other a cathode As a feature structure and the different pole, configurations and to different pole polarity of adjacent electrodes of each electrode pair by the other as well as to the cathode either the adjacent electrodes of each electrode pair to the anode, repeating the Yes.
[0008]
Furthermore, the phosphate ion-containing wastewater treatment apparatus according to the present invention uses an electrode containing iron ions and / or aluminum ions to electrochemically elute iron ions and / or aluminum ions into the wastewater containing phosphate ions. A wastewater treatment method for coagulating and precipitating acid ions in the form of an insoluble salt with iron and / or aluminum, wherein at least two pairs of electrodes are disposed in the wastewater, and the polarity of the adjacent electrodes of each electrode pair is determined. After the predetermined electrolysis time has elapsed, the polarity of the electrodes in each electrode pair is converted, and after the predetermined electrolysis time has elapsed, the polarities of the adjacent electrodes of each electrode pair are made different from each other. Then, after a predetermined electrolysis time has elapsed, the polarity of the adjacent electrodes of each electrode pair is converted.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the processing apparatus and the processing method of the phosphate ion containing waste_water | drain of this invention are demonstrated based on an accompanying drawing.
[0010]
FIG. 1 is an explanatory view showing an embodiment of a treatment apparatus for phosphate ion-containing waste water of the present invention, FIG. 2 is an enlarged view of the treatment apparatus in FIG. 1, and FIG. 3 is an embodiment of the treatment method of the present invention. It is explanatory drawing shown.
[0011]
The processing apparatus of this invention is used for a merged septic tank, for example. As shown in FIG. 1, the combined septic tank comprises a first anaerobic filter bed tank A, a second anaerobic filter bed tank B, a biological filter tank C, a treated water tank D, and a disinfection tank E. 1 Anaerobic filter The waste water flowing into the floor tank A is treated in each tank and then discharged from the disinfection tank E. And the processing apparatus 1 is installed in the circulation path which returns the treated water pumped up by the air pump F from the said treated water tank D to the 1st anaerobic filter bed tank A.
[0012]
As shown in FIGS. 1 and 2, the treatment apparatus 1 is disposed such that a wastewater treatment chamber 4 having a drainage inlet 2 and a drainage outlet 3 and at least a part of the wastewater in the treatment chamber 4 is immersed in the wastewater. Electrodes 5, 6, a power source 7 for energizing the electrodes 5, 6, a polarity conversion device 8 for switching the electrolysis of the electrodes 5, 6, and air in the waste water in the waste water treatment chamber 4 Is provided with an air aeration device 9 for supplying air.
[0013]
The electrodes 5, 6 can be fabricated from iron ions and / or aluminum ion sources such as iron, iron alloy, aluminum, aluminum alloy or iron-aluminum alloy.
[0014]
As shown in FIGS. 1 and 2, the electrodes 5 and 6 are suspended in the drainage by the insulating support column 10 with respect to the power source 7. Further, a terminal 11 is fixed to the electrodes 5 and 6 by screwing or soldering, and a lead wire 12 drawn from the terminal 11 is connected to a power source 7.
[0015]
In this embodiment, the electrodes 5 and 6 are arranged in three pairs A1, A2 and A3 in the waste water. Among the electrodes 5 and 6, the electrode 5 is an anode (anode) side electrode, and the electrode 6 is a cathode. The electrode is on the (cathode) side. Also, the electrodes adjacent to each of the electrode pairs A1 to A3, that is, the electrode 6 in the electrode pair A1 and the electrode 6 in the electrode pair A2, and the electrode 5 in the electrode pair A2 and the electrode 5 in the electrode pair A3 are arranged in the same polarity. Has been. The polarity conversion device 8 switches the electrolysis performed between the electrode pairs A1 to A3 and between the electrode pairs A1 and A2 and the electrode pairs A2 and A3.
[0016]
For example, as shown in FIGS. 3A to 3B, after a predetermined electrolysis time has elapsed, the polarities of the electrodes 5 and 6 in the electrode pairs A1 to A3 are converted, and the electrodes in the electrode pairs A1 to A3 are converted. Continue electrolysis between 5 and 6. Then, after a predetermined electrolysis time has elapsed, as shown in FIG. 3C, the polarities of the adjacent electrodes 6 and 6 of the electrode pair A1 and the electrode pair A2 are changed to different polarities, and the electrode pair A2 and the electrode pair are converted. The polarity of adjacent electrodes 5 and 5 of A3 is converted to a different polarity, and the surface to be electrolyzed is changed. In addition, since the electrode 5 in the electrode pair A1 and the electrode 6 in the electrode pair A3 at this time do not have electrodes having different polarities, energization is stopped. Next, after a predetermined electrolysis time has elapsed, as shown in FIG. 3D, the polarities of the adjacent electrodes 6 and 6 of the electrode pair A1 and the electrode pair A2 are changed to different polarities, and the electrode pair A2 and the electrode The polarity of the adjacent electrodes 5 and 5 of the pair A3 is changed to a different polarity, and electrolysis is continued. Next, after a predetermined electrolysis time has elapsed, as shown in FIG. 3A, the polarities of the adjacent electrodes of the first electrode pairs A1 to A3 are converted to the same polarity.
[0017]
The conventional electrode polarity conversion operation is one cycle and the electrolysis is continued.
[0018]
The predetermined electrolysis time can be set to 10 minutes or longer, preferably 30 minutes or longer, since elution efficiency decreases when it is less than 10 minutes. In this embodiment, three pairs of electrodes are disposed in the waste water. However, the present invention is not limited to this, and two pairs or four or more electrodes are disposed in the waste water. be able to.
[0019]
In this embodiment, since the electrodes are electrolyzed alternately on both sides, the distance between the electrodes can be prevented from increasing, power consumption can be prevented from increasing, and deposits such as oxides are attached. It becomes difficult and the amount of elution is not reduced. Furthermore, since the distance between each electrode pair can be made smaller than before, the processing apparatus can be made compact.
[0020]
The air aeration apparatus 9 includes a porous air diffusion tube 13 or an air diffusion plate installed at the bottom center of the waste water treatment chamber 4 and an air pump 14 for sucking compressed air into the air diffusion tube 13. The air diffuser 13 and the air pump 14 are connected by a pipe 15.
[0021]
In the present embodiment, the air diffuser 13 is installed in the center of the bottom of the waste water treatment chamber 4, but in the present invention, the present invention is not particularly limited to this. A position where water-insoluble salt, which is a reaction product of phosphate ions in the waste water and iron ions (aluminum ions) eluted from the electrodes, can be easily selected and installed. For example, the air diffuser 13 is installed perpendicular to the wall 4a on the outlet 3 side of the waste water treatment chamber 4, but the air diffuser 13 is close to the wall 4a and parallel to the wall 4a, that is, FIG. In addition to the vertical direction of the paper surface, it is arranged at a slightly higher position from the bottom to facilitate convection of the waste water in the processing chamber. Further, the convection of the waste water can be easily generated by moving the diffuser pipe vertically in the waste water in the processing chamber. In the present embodiment, the reactivity of iron ions and phosphate ions can be improved by stirring the waste water.
[0022]
A conventionally known method can be adopted as the electrolytic elution method for iron (aluminum), and the electrode may be energized continuously, intermittently, or pulsed. The amount of energization varies depending on the concentration of phosphate ions and other ions, the flow rate of wastewater, etc., but the ratio of the concentration of iron ions and / or aluminum ions in the wastewater / phosphate ion concentration (hereinafter abbreviated as “Fe / P”). ) May be adjusted to 0.8 to 3.0, preferably 1.0 to 2.5.
[0023]
In the present invention, the treatment by the electrolytic elution method of iron (aluminum) of the phosphate ion-containing wastewater is carried out by reacting the iron ion (aluminum ion) eluted from the electrode with the phosphate ion in the wastewater to form water-insoluble phosphoric acid and iron. Although a reaction (reaction A) that forms a salt with (aluminum) is utilized, hydroxide ions are present in the waste water, and the eluted iron ions (aluminum ions) also react with the hydroxide ions ( Reaction B). Since reaction B is faster than reaction A, in order to capture phosphate ions, it is necessary to increase the amount of current and increase the elution amount of iron ions (aluminum ions).
[0024]
However, when calcium ions or magnesium ions are present in the waste water, these ions react with hydroxide ions (Reaction D). Since this reaction D has priority over reaction B between iron ions (aluminum ions) and hydroxide ions, reaction B is suppressed, and iron ions (aluminum ions) are effectively used for reaction A with phosphate ions. Furthermore, calcium ions and magnesium ions also react with phosphate ions to form water-insoluble salts, thus contributing to the removal of phosphate ions.
[0025]
For this reason, in this invention, calcium ion or magnesium ion is added, reaction B of iron ion (aluminum ion) and hydroxide ion is suppressed, and reaction A of iron ion (aluminum ion) and phosphate ion is efficiently performed. It can also be made. Thereby, the amount of energization can be reduced, power can be saved, and the elution amount of iron and aluminum can be reduced.
[0026]
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 can be combined with other purification systems such as activated sludge method, membrane separation method, anaerobic / aerobic circulation method, etc. to make a comprehensive wastewater purification system for households and collective housing. it can. It can also be used in large-scale processing systems (human waste treatment plants).
[0027]
Next, the present invention will be described based on examples, but the present invention is not limited to such examples.
[0028]
EXAMPLE Using an iron electrolysis elution waste water treatment apparatus shown in FIG. 1, a phosphate ion concentration of 5 mg / liter (added as H ₃ PO ₄ ), Na ⁺ 200 mg / liter and Ca ²⁺ 20 mg / liter is supplied from the inlet. The test wastewater was introduced at a flow rate of 1 liter / min.
[0029]
High purity iron plates were used as the three pairs of electrodes immersed in the waste water. Then, as shown in FIG. 3, the electrode was controlled to be electrolyzed on both sides. The energization time at this time was 30 minutes, and the energization amount to the electrode was 1.2 A so that Fe / P was 1.5.
[0030]
Then, by electrolysis of the electrode, the eluted iron ions react with phosphate ions to produce water-insoluble salts. The generated salt is stirred together with the inflowing water by the air (2 liter / min) generated from the air diffuser and flows out to the outflow side. Therefore, there was almost no accumulation of water-insoluble salts.
[0031]
Next, as a result of examining the filtrate obtained by filtering the waste water collected at the outlet with a filter having a pore diameter of 0.45 μm in accordance with the total phosphorus analysis method (46.3) standardized in JIS K 0102, the removal efficiency of phosphorus was 90%. It turns out that it is above.
[0032]
【The invention's effect】
As described above, according to the present invention, since both surfaces of the electrodes are uniformly dissolved except for the electrodes on both sides of the electrode pair, it is possible to prevent the distance between the electrodes from increasing and prevent an increase in power consumption. be able to.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an embodiment of a treatment apparatus for phosphate ion-containing waste water of the present invention.
FIG. 2 is an enlarged view of the processing apparatus in FIG.
FIG. 3 is an explanatory diagram showing an embodiment of a processing method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Inlet 3 Outlet 4 Processing chamber 5, 6 Electrode 7 Power supply 8 Polarity conversion apparatus 9 Air aeration apparatus 10 Insulating support | pillar 11 Terminal 12 Lead wire

Claims (4)

A waste water treatment chamber having a waste water inlet and a water outlet, an electrode disposed at least partially immersed in waste water in the treatment chamber, and containing an iron ion and / or aluminum ion source; A wastewater treatment apparatus comprising a power source for energizing the electrodes, wherein at least two pairs of electrodes are disposed,
A configuration in which the polarity of adjacent electrodes of each electrode pair is the same polarity, and one electrode in each electrode pair is an anode and the other electrode is a cathode, and the polarity of adjacent electrodes in each electrode pair is the same polarity; A structure in which one electrode in each electrode pair is used as a cathode and the other electrode is used as an anode, and one of adjacent electrodes in each electrode pair is used as an anode and the other is used as a cathode so that adjacent electrodes of each electrode pair The polarity that repeats the configuration of making the polarity of each electrode pair different and the configuration that makes the polarity of the adjacent electrodes of each electrode pair different from each other by using one of the adjacent electrodes of each electrode pair as a cathode and the other as an anode An apparatus for treating wastewater containing phosphate ions, comprising a conversion device. Using an electrode containing iron ions and / or aluminum ions, iron ions and / or aluminum ions are electrochemically eluted into waste water containing phosphate ions, and phosphate ions are in the form of insoluble salts with iron and / or aluminum. The wastewater treatment method for coagulating and precipitating with at least two pairs of electrodes disposed in the wastewater,
A configuration in which the polarity of adjacent electrodes of each electrode pair is the same polarity, and one electrode in each electrode pair is an anode and the other electrode is a cathode, and the polarity of adjacent electrodes in each electrode pair is the same polarity; A structure in which one electrode in each electrode pair is used as a cathode and the other electrode is used as an anode, and one of adjacent electrodes in each electrode pair is used as an anode and the other is used as a cathode so that adjacent electrodes of each electrode pair A configuration in which the polarities of the adjacent electrodes of each electrode pair are different from each other, and a configuration in which the polarity of the adjacent electrodes of each electrode pair is made different from each other by making one of the adjacent electrodes of each electrode pair a cathode and the other an anode. Treatment method for waste water containing acid ions.   Using an electrode containing iron ions and / or aluminum ions, iron ions and / or aluminum ions are eluted electrochemically into waste water containing phosphate ions, and phosphate ions are in the form of insoluble salts with iron and / or aluminum. In the wastewater treatment method for coagulating sedimentation, at least two pairs of electrodes are arranged in the wastewater, the polarities of the adjacent electrodes of each electrode pair are made the same polarity, and then a predetermined electrolysis time has passed, The polarity of the electrodes in each electrode pair is converted, and then after a predetermined electrolysis time has elapsed, the polarity of the adjacent electrodes of each electrode pair is converted to a different polarity, and then after a predetermined electrolysis time has elapsed, A method for treating phosphate ion-containing wastewater that converts the polarity of adjacent electrodes of each electrode pair.   The processing method according to claim 3, wherein energization of the electrodes on both sides is stopped when the polarity of adjacent electrodes of each electrode pair is converted to a different polarity.

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