KR100404863B1 - METHOD AND APPARATUS FOR PROCESSING PHOSPHORIC ION DISTRIBUTION - Google Patents

Abstract

The electrolytic dissolution method is performed in a state where the concentration of calcium ions and / or magnesium ions in the wastewater to be treated is 2 mg / L or more. The removal efficiency of the phosphate ion-containing wastewater by the electrolytic dissolution method of iron or aluminum in the phosphate ion removal method can be improved and power saving can be achieved.

Description

METHOD AND APPARATUS FOR PROCESSING PHOSPHORIC ION DISTRIBUTION

The present invention relates to a method and apparatus for treating living wastewater containing phosphoric acid ions such as wastewater, in particular domestic wastewater or wastewater in a housing complex.

It is a fact to note that there is the presence of phosphorus compounds in one of the causes of eutrophication of rivers and lakes. In addition, this phosphorus compound is present in the living water of ordinary households rather than the plant drainage, so that purification treatment is difficult and effective measures are not taken at present.

Various methods for purifying phosphorus compounds have been proposed, but electrolytic elution of iron has been known for domestic drainage (JP-A-3-89998). This technology is a technique to remove phosphorus ions in drainage by reacting with iron ions to coagulate and precipitate as insoluble salts such as FePO ₄ or Fe (OH) _x (PO ₄ ) _y , To dissolve iron ions in the wastewater.

However, this electrolytic electrolytic dissolution method has a problem that even if the amount of phosphoric acid ion is the same, the phosphate ion removal efficiency fluctuates largely depending on the kind of the drainage, and purification of the drainage water can not be stably obtained.

The inventors of the present invention have investigated the causes thereof and found that when the removal rate of phosphate ions is closely related to the concentration of calcium ions and magnesium ions in the wastewater and the concentration of calcium ions or magnesium ions is less than 2 mg / The removal efficiency of the phosphoric acid ions is greatly reduced.

As the wastewater treatment apparatus using the above electrolytic dissolution method, for example, anaerobic treatment of living wastewater which has flowed into a shape tank by anaerobic (anaerobic) treatment is followed by aerobic treatment in an erecting tank, And the fermented iron is dissolved in an anaerobic tank in an anaerobic tank to react with orthophosphoric acid in the treated water to form a sparingly soluble compound which is then agglomerated and precipitated, And the sludge returned to the anaerobic tank is removed by aspiration (Japanese Patent Application Laid-Open No. 7-108296).

However, even in this method, there is a problem that the removal efficiency of the phosphoric acid ion varies greatly depending on the kind of drain water even if the amount of phosphoric acid ion is the same, and stable purification can not be obtained.

On the other hand, there is a method of adding a coagulant such as CaCl ₂ or Fe ₂ Cl ₃ to the waste water as a purification treatment method of the phosphorus compound.

However, as such a purification treatment method, it is necessary to adjust the pH by the kind of the flocculant to increase the phosphorus removal rate. For example, when CaCl ₂ is used as a flocculant, since the removal rate of pH 9 to 10 is the highest, NaOH solution or the like must be added as a pH adjusting agent. Therefore, in the above-described purification treatment method, two kinds of chemicals such as a flocculant and a pH adjuster need to be added to drain water in order to remove phosphorus compounds, and there is a problem that the pH must always be observed. The amounts of the above coagulants such as CaCl ₂ and FeCl ₃ are converted into Fe / P = 2 to 3 and Ca / P = 2 to 3 in terms of molar ratio with respect to phosphorus in the waste water. As such, a large amount of coagulant is required for phosphorus, so that there is a problem that the cost is increased.

In addition, since the conventionally proposed method for purifying phosphorus compounds uses a drug that is connected to environmental destruction during the treatment, it is necessary to perform post-treatment again or a plurality of drugs are used. There was a problem.

Here, the inventors of the present invention have studied and studied variously in order to achieve stable purification of wastewater efficiently and in an environmentally safe manner. When the wastewater contains phosphate ions, calcium ions and / or magnesium ions, it has been found that adjusting the pH to 8 or more makes it easy to form an insoluble salt in water and can achieve the purification of the above-mentioned water. Thus, the present invention has been completed.

An object of the present invention is to improve the removal rate of phosphorus ion-containing wastewater by the electrolytic dissolution method of iron or aluminum in the phosphate ion removal method and to save power. It is also intended to adjust the pH easily without using a pH adjusting agent. It is also intended to efficiently and safely purify wastewater containing phosphate ions and calcium ions and / or magnesium ions.

1 is a schematic explanatory diagram of one embodiment of a wastewater treatment apparatus for carrying out the method of the first invention

2 is a graph showing the relationship between the calcium ion concentration and the phosphate ion removal rate in the case of using the iron electrode in Example 1 of the first invention.

3 is a graph showing the relationship between the magnesium ion concentration and the phosphate ion removal rate in the case of using the iron electrode in Example 2 of the first invention.

4 is a graph showing the relationship between the calcium ion concentration and the phosphate ion removal rate in the case of using the aluminum electrode in Example 3 of the first invention.

5 is a graph showing the relationship between the magnesium ion concentration and the phosphate ion removal rate when the aluminum electrode is used in Example 4 of the first invention.

6 is an explanatory view showing an embodiment of the apparatus for treating waste water containing phosphorus ions according to the third invention.

7 is an explanatory view showing another embodiment of the apparatus for treating waste water containing phosphorus ions according to the third invention.

8 is a schematic explanatory view showing another arrangement example of electrodes in the second to third inventions;

Fig. 9 is an explanatory view showing another example of electrodes in the second to third inventions; Fig.

10 is an explanatory view showing still another example of the electrode in the second to third inventions;

11 is an explanatory view showing an embodiment of the apparatus for treating waste water containing phosphorus ions according to the sixth invention.

12 is an explanatory view showing another embodiment of the apparatus for treating phosphate-ion-containing wastewater of the sixth invention;

13 is an explanatory view showing another embodiment of the waste water treatment apparatus of the sixth invention;

14 is an explanatory view showing an embodiment of the apparatus for treating phosphate-ion-containing wastewater according to the eighth invention.

15 is an explanatory view showing another embodiment of the apparatus for treating waste water containing phosphorus ions according to the eighth invention.

16 is an explanatory view showing still another embodiment of the apparatus for treating phosphate ion-containing wastewater according to the eighth invention.

Fig. 17 is an explanatory view showing still another embodiment of the apparatus for treating waste water containing phosphate ions of the eighth invention; Fig.

18 is a schematic explanatory view of one embodiment of a wastewater treatment apparatus used in the ninth to tenth embodiments of the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

1. Drainage treatment room

2. Drainage

3. Inlet

4. Outlet

5. Electrode

6. Power

100. Diaphragm

115. pH meter

116. pH controller

117. pH adjusting agent addition device

The method of treating phosphorus ion-containing wastewater according to the first aspect of the present invention is a method for treating phosphorus ion-containing wastewater, comprising the steps of electrochemically eluting iron ions and / or aluminum ions into wastewater containing phosphorus ions using an electrode containing iron ions and / A method for treating wastewater which is coagulated and sedimented in the form of an insoluble salt with water and iron and / or aluminum, comprising the steps of: discharging calcium ions in a wastewater to be treated, a magnesium ion concentration or a total concentration of calcium ions and magnesium ions of 2 mg / As shown in FIG.

The method for treating phosphate ion-containing wastewater according to the second aspect 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, Is precipitated in the form of a salt insoluble in water with iron and / or aluminum, characterized in that the calcium ion concentration in the wastewater to be treated and the calcium ion and / or magnesium ion generation source are present in the electrode .

The apparatus for treating waste water containing phosphorus ions according to a third aspect of the present invention comprises a drainage treatment chamber having an inlet and an outlet for waste water, an electrode arranged so that at least a part of the waste water is immersed in the waste water and a power source for energizing the electrode Characterized in that at least one of the electrodes comprises a source of calcium ions and / or a source of magnesium ions and an source of iron ions and / or aluminum ions.

The method for treating phosphate-ion-containing wastewater according to the fourth aspect of the present invention is a method for treating phosphorus ion-containing wastewater by electrochemically eluting iron ions and / or aluminum ions into wastewater containing phosphate ions using an electrode containing iron ions and / Is precipitated in the form of a salt insoluble in water with iron and / or aluminum, characterized in that a source of calcium ions and / or magnesium ions is present in the waste water.

The calcium and / or magnesium ion generating source used in the waste water treatment method of the fifth aspect of the present invention is preferably at least one selected from the group consisting of metal calcium, metal magnesium, and compounds capable of eluting calcium ions and / And a control unit.

The apparatus for treating waste water containing phosphorus ions according to a sixth aspect of the present invention comprises a drainage treatment chamber having an inlet and an outlet for waste water, an electrode arranged so that at least a part of the waste water is immersed in the waste water in the treatment chamber and a power source for energizing the electrode And at least one of the electrodes includes a ferric ion and / or an aluminum ion generating source, and a calcium ion and / or a magnesium ion generating source is arranged in front of the inlet or in the above-mentioned wastewater treatment room.

The method for treating waste water containing phosphate ions according to the seventh aspect of the present invention is a waste water treatment method for coagulating and sedimenting phosphoric acid ions from wastewater containing phosphate ions in the form of insoluble salts in water, Characterized in that a direct current is energized and a source of calcium ions and / or magnesium ions is charged in the vicinity of the cathode and / or a source of iron ions and / or an aluminum ion is charged in the vicinity of the anode.

The apparatus for treating waste water containing phosphorus ions according to an eighth aspect of the present invention includes a drainage treatment chamber having an inlet and an outlet for drainage, at least a pair of electrodes arranged so that at least a part of the electrode is immersed in drainage in the treatment chamber, And when an electric current is supplied to the pair of electrodes, an iron ion and / or an aluminum ion source applying device in the vicinity of the calcium ion and / or magnesium ion source introducing device and / or the anode in the vicinity of the electrode, Is installed.

The wastewater treatment method of the ninth aspect is characterized in that the pH of the wastewater containing phosphate ions, calcium ions and / or magnesium ions is adjusted to 8 or more.

The waste water treatment method of the tenth aspect of the present invention is a waste water treatment apparatus for treating wastewater containing phosphate ions, calcium ions and / or magnesium ions, comprising a pH meter for detecting the pH of the lake water, a pH adjuster adding apparatus for adding a pH adjuster to the wastewater, And when the pH value of the pH meter becomes less than 8, the addition of a pH adjuster is instructed to the pH adjuster addition device to maintain the pH of the wastewater at 8 or more.

Next, a method and apparatus for treating phosphate ion-containing wastewater according to the present invention will be described with reference to the accompanying drawings.

The treatment of electrolytic dissolution of iron with phosphorus ion-containing wastewater uses a reaction (reaction A) in which iron ions eluted from the electrodes react with phosphate ions in the wastewater to form water-insoluble salts of phosphoric acid and iron Hydroxide ions (OH ^- ions) are present in the drainage and eluted iron ions also react with hydroxide ions (reaction B). Since reaction B is faster than reaction A, it is necessary to increase the elution amount of iron ions by increasing the amount of current in order to capture phosphoric acid ions. As a result, the consumption of the electrodes and electric power is increased.

The first aspect of the present invention is to inhibit the reaction B of iron ions and hydroxide ions and efficiently conduct reaction A between iron ions and phosphate ions, and thus calcium ions and / or magnesium ions are present at a concentration of 2 mg / Feature.

When calcium ions or magnesium ions are present in the wastewater, they react with hydroxide ions (reaction D). This reaction D takes priority over the reaction B between the iron ion and the hydroxide ion, so that the reaction B is inhibited and the iron ion is effectively used for the reaction A with the phosphate ion. In addition, calcium ions and magnesium react with temperature phosphate ions to form water-insoluble salts (Reaction E), thereby contributing to the removal of phosphate ions.

Since Reaction A is promoted on the acid side (pH 4 to 5) and Reaction E is promoted on the alkaline side (pH 9 to 11), Reaction A on the anode (yard side) and Reaction E on the cathode .

Reaction A of phosphate ions with iron ions and reaction E of phosphate ions with calcium ions or magnesium ions produces insoluble salts in various forms of water such as salts and hydrates depending on the reaction conditions. Therefore, a salt insoluble in water as a salt with phosphoric acid is included in the salt of phosphoric acid and iron, calcium, and magnesium in the present invention.

When the effect of such a calcium ion or magnesium ion starts to significantly affect the removal of phosphate ions of iron ions, as shown in Figs. 2 and 3, a concentration of calcium ions or magnesium ions in the wastewater is 2 mg / l to be.

In the case of exceeding 2 mg / l, up to 10 mg / l, the removal rate of phosphate ions increases rapidly in response to the concentration of calcium ions or magnesium ions, and if it exceeds 10 mg / l, the increase in the removal rate of phosphate ions becomes gentle.

In the present invention, aluminum, which forms salts insoluble in phosphate ions and water, can be used instead of or in combination with iron. In the case of aluminum, as shown in Figs. 4 and 5, there is no abrupt change as in the case of iron due to the presence of calcium ions or magnesium ions, but the removal rate of phosphate ions is certainly improved by the presence of calcium ions or magnesium ions.

According to the first discovery discovered by the present inventors for the first time, the calcium ion concentration, the magnesium ion concentration, or the total concentration thereof in the wastewater is 2 mg / L or more, preferably 2 to 10 mg / L Phosphorus ions are removed by electrolytic elution of iron or aluminum.

The means for allowing the calcium ion or the magnesium ion to be present in the waste water at a concentration of 2 mg / L or more is not particularly limited. For example, the source of the calcium ion or the magnesium ion is discharged as a solid or an aqueous solution Or when the concentration of calcium ions or magnesium ions existing in the waste water is lowered, the calcium ion or magnesium ion source is disposed in the electrode continuously or continuously in a continuous manner when the concentration of the calcium ion or the magnesium ion is lowered. And the like.

Calcium carbonate (solubility: 1.4 mg / 100 g of water), calcium oxalate (solubility: 0.67 mg / 100 g of water) and calcium carbonate (solubility: , Magnesium chloride (solubility: 52.8 g / water 100 g), magnesium hydroxide (solubility: 0.9 mg / water 100 g), magnesium carbonate (solubility 10.6 mg / water 100 g) and magnesium oxalate have.

Among them, calcium carbonate, magnesium hydroxide, calcium oxalate and the like are particularly preferable when it is desired that the calcium ion or the magnesium ion is gradually released in a small amount by elution. In addition, even in the case of a good water-soluble salt, it is also possible to impart a property of being slowly released externally, such as covering with a water-permeable membrane.

For the electrolytic dissolution of iron (aluminum), a conventionally known method may be employed, and as the electrode, iron, an iron alloy, aluminum, an aluminum alloy, or the like is used. The energization can be continuous, intermittent or pulsed. The flow rate of the electrolytic solution varies depending on the concentration of phosphoric acid ions or other ions, the flow rate of the drain water, and the like, but the ratio of the concentration of iron ion and the concentration of phosphoric acid ion in the drainage of aluminum ion (hereinafter abbreviated as "Fe / P") is 0.8 to 3.0, Preferably 1.0 to 2.5. According to the present invention, such a quantity of electricity to be supplied can be greatly reduced and the amount of iron and aluminum to be eluted can be reduced while saving power.

The method of treating wastewater of the present invention can be particularly advantageously used for general household wastewater as described above. Therefore, it can be used alone, but it can be combined with another purification system such as an activated sludge method, a membrane separation method, an anaerobic system, an exhalation circulation method, and the like to provide a total drainage purification system for domestic and collective housing. It can also be used for a large-scale treatment system (urine treatment plant).

Next, the method of the first invention will be described based on examples, but the present invention is not limited to such examples.

Example 1

The electrolytic electrolytic effluent treatment apparatus shown in Fig. 1 was used to conduct electrolysis by using water containing a phosphoric acid ion concentration of 15 mg / l or a phosphorus concentration of 5 mg / l (added as H ₃ PO ₄ ) and Na ⁺ 200 mg / I did.

1, reference numeral 1 denotes a drainage processing chamber, which has an inlet 3 and an outlet 4 of the drainage 2. In the drainage processing chamber 1, two high-purity iron electrodes 5 immersed in the drainage 2 are arranged and connected to the power source 6. [ The amount of current to be applied to the electrodes was set to 467 mA, 933 mA, and 1400 mA such that Fe / P was 0.9, 1.8, and 2.7, respectively, and the polarity was reversed every 30 minutes in any case. Calcium hydroxide as a calcium ion source was added to the test wastewater so as to have calcium ion concentrations of 0, 2, 3, 4, 5, 10 and 50 mg / l, and flowed at a flow rate of 0.5 l / min. The phosphoric acid ion concentration in the wastewater of the treating agent was determined by measuring the amount of the wastewater collected at the outlet 4 at a time of 2 hours from the start of the energization with a filter having a pore diameter of 0.45 mu m using the full method (Japanese Industrial Standards (JIS) K 0102 46.3). The results are shown in Fig.

It can be seen from Fig. 2 that the removal rate of phosphate ions is rapidly increasing at the time of the calcium ion concentration of 2 mg / l. Also, the larger the Fe / P ratio, the greater the removal rate.

Example 2

Except that magnesium ion (source: magnesium chloride) was added to the test wastewater so as to have concentrations of 0, 3, 5, 10 and 50 mg / l instead of calcium ion in Example 1, The concentration of the phosphate ion was measured in the same manner as in Example 1. The results are shown in Fig.

As is apparent from Fig. 3, the removal rate of phosphate ions is rapidly increasing at a concentration of about 2 mg / l for magnesium ions, and the removal rate is also improved when Fe / P is increased.

Example 3

A high-purity aluminum electrode was used as an electrode in Example 1, and the amount of electricity was adjusted so that Al / P (ratio of aluminum ion concentration / phosphoric acid ion concentration in the waste water to be treated) was 0.6, 1.2 and 1.8, Was adjusted to 0.5 and 10 mg / l, and the concentration of phosphate ions in the wastewater of the treatment agent was measured in the same manner as in Example 1. [ The results are shown in Fig.

4, when Al / P is around 1, the removal rate of the phosphate ion increases from the vicinity of 5 mg / L of the calcium ion concentration, but when Al / P increases, the removal rate starts to increase at the calcium ion concentration of about 2 mg / Able to know.

Example 4

In the same manner as in Example 1, the concentration of phosphate ions in the wastewater of the treatment agent was measured by the same method except that magnesium ion (source of magnesium chloride) was added to the test wastewater instead of calcium ion in Example 3. The results are shown in Fig.

As apparent from Fig. 5, when the magnesium ion is added, the removal rate of the phosphate ion starts to increase from the low concentration (2 mg / l). According to the method of the first aspect of the present invention, it is possible to remove phosphate ions in the waste water at a high rate, and also to reduce consumption of iron or aluminum as an electrode and power for dissolving the waste water, .

Next, the second to third inventions will be described. 6, the treatment apparatus comprises a drainage treatment chamber 1 having an inlet 3 and an outlet 4 for draining water, and electrodes 7, 8 arranged so as to at least partially immerse in drainage in the treatment chamber 1 And a power supply 6 for energizing the electrodes 7 and 8. As the ion generating source for removing phosphate ions from the base metal such as iron, iron alloy, aluminum, aluminum alloy or iron-aluminum alloy, water or the like of calcium or magnesium may be used for the electrodes 7 and 8. Specific examples of such water-soluble salts include the water-soluble salts of the first invention described above. As a method for incorporating these ion generating sources into the base metal, a method of injecting CaCO ₃ or the like as described above (when a base metal and CaCO ₃ are charged into a mold to melt the base metal by arc welding or the like and then cooled It is preferable to connect a control device 9 for controlling the current flowing between the electrodes 7 and 8 to the power source 6 described above.

The surface of the electrode 7 on the anode side, for example, is oxidized to form an organic film or an inorganic oxide film on the surface, but the surface of the electrode 8 on the cathode side is cleaned by hydrogen gas generated from the steel material on the cathode side or the aluminum material, I never do that. For this reason, when the control device 9 generates an oxide film on the surface of the electrode 7 on the anode side and the amount of iron ion or aluminum ion is reduced, the polarity is reversed at a predetermined time interval.

Thus, the elution amount of iron ions can be kept substantially constant, so that the denitrification performance can be kept constant. Further, as the time of inversion, for example, in case of less than 1 hour, the elution amount of iron ion decreases, so it is preferable to set it to 1 hour or more.

In the present embodiment, each of the two electrodes includes a source of calcium ions and / or a source of magnesium ions, but the present invention is not limited thereto. Even if only one of the two electrodes contains a source of calcium ions and / or magnesium ions do. As shown in Fig. 7, the electrodes 14 and 15 may be formed by coating and laminating the above-described compound layer 17 composed of the calcium ion and / or magnesium ion generating source on the base metal 16. It is preferable that the compound layer 17 is provided such that the metal ions eluted from the base metal 16 are opposed to each other so as to be less affected by hydroxide ions generated in the counter electrode. In the embodiment shown in Figs. 6 to 7, a pair of opposed electrodes is used. However, the present invention is not limited to this arrangement and number, and the number of electrodes on the anode side and the cathode side can be appropriately set, And can be changed in various ways. For example, as shown in Fig. 8 (a), the electrode group 24 of a plurality of rows on the cathode side and the electrode group 25 of a plurality of rows on the anode side can be opposed to each other. As shown in Fig. 8 (b), the electrode 35 on the positive electrode side and the electrode 34 on the negative electrode side may be arranged alternately. Further, the number of electrodes on the anode side and the number of electrodes on the cathode side may not be the same.

Another example of the electrode used in the present invention is shown in Figs. 9 to 10. Figure 9 is obtained by the electrodes shown in the calcium ion and / or magnesium ion source 41 within the holes of the base metal 40 having a plurality of holes for instance filling the CaCO ₃ in particle form. The electrode shown in Fig. 10 is obtained by filling calcium ions and / or magnesium ion generating sources 51, for example, CaCO ₃ , into the meshes of the base metal 50 made into meshes.

Next, the second to third inventions will be described based on the embodiments, but the present invention is not limited to these embodiments.

Example 5

Using the iron electrolytic effluent discharged water treatment apparatus shown in Fig. 6, test wastewater containing a phosphate ion concentration of 5 mg / l (added as H ₃ PO ₄ ) and Na ⁺ 200 mg / l was introduced from the inlet at a flow rate of 1 l / min.

As the electrodes to be polished in the drainage, 1000 mg of CaCO ₃ was contained in a high-purity iron plate by the arc melting method. The amount of current to be applied to the electrode was set to 1.2 A so that Fe / P was 1.5, and the polarity was reversed every 0.5 hour.

The electrolysis of the electrodes simultaneously released iron ions and calcium ions. Since the solubility of CaCO ₃ was 15 mg / l for water at 25 ° C, the calcium ion concentration in the test water was 6 mg / l, which was over 2 mg / l. The filtrate obtained by filtering the wastewater collected at the outlet 4 with a filter having a pore size of 0.45 탆 after energizing for 2 hours was examined according to the full-blown analysis method (46.3) specified in Japanese Industrial Standard K 0102. As a result, Or more.

Example 6

Except that CaCO ₃ contained in the electrode in Example 5 was replaced by soluble Ca (OH) ₂ , the same apparatus was used under the same test conditions. At this time, the calcium ion concentration in the test water discharged from the outlet was 12 mg / l.

As a result of examining the content of phosphorus in the same manner as in Example 5 after the elapse of the energization time of half of Example 5, it was found that the removal efficiency of phosphorus was 90% or more. As in the case of this example, the calcium ion concentration is twice the calcium ion concentration in Example 5, so that the removal efficiency (90% or more) of phosphorus as in Example 5 can be obtained with a half of the energization time, I can see that it can halve.

According to the second to third inventions, it is possible to remove phosphate ions in the waste water at a high rate, and also to reduce the consumption amount of iron or aluminum as the electrode and the electric power for dissolving, and to operate the waste water treatment continuously for a long time at a low power .

Next, the fourth to fifth inventions will be described.

11, the treatment apparatus includes a drainage treatment chamber 1 having an inlet 3 and an outlet 4 for draining water and electrodes 54, 55 arranged so that at least a part of the drainage in the treatment chamber 1 is immersed A power source 6 for energizing the electrodes 54 and 55 and an ion generating source 60 for removing phosphoric ions disposed in the drainage processing chamber 1. Reference numeral 9 denotes a control device for controlling the current flowing between the electrodes 54 and 55. The electrodes 54 and 55 are made of iron, an iron alloy, aluminum, an aluminum alloy, or an iron-aluminum alloy.

There are three types of ion generating sources, that is, a calcium ion generating source, a magnesium ion generating source, and an ion generating source in which these are combined. As the above-mentioned calcium ion generating source, the water-soluble salt according to the first invention can be mentioned. As a method for disposing these ion generating sources in the above-mentioned waste water treatment chamber 1, there are a method in which a particle or bulk ion generating source 60 is surrounded by a net 61 or a filter and installed in the waste water treatment chamber 1, ) Is enclosed in a net or filter and put in the drainage, or a method in which the ion generating source is covered with a case and installed on the inflow side. However, if the method in which calcium ions and / or magnesium ions can be eluted into the waste water treatment room But is not limited thereto. In the present embodiment, the ion generating source is disposed in the drainage processing chamber 1, but the present invention is not limited to this. For example, as shown in Fig. 12, a dissolving tank 62 installed in front of the inlet 3 for drainage water, An ion generating source 66 may be disposed.

In the case of disposing the dissolution tank 62 in such a dissolution tank 62, the dissolution tank 62 and the waste water treatment chamber 1 are connected to each other by a pipe through a pump 63 and calcium ions and / or magnesium ions are dissolved in the dissolution tank 62 The drain water can be pumped up by the pump 63 and flowed to the drainage processing chamber 1. [ Further, the dissolution tank may be located higher than the drainage treatment chamber and drainage water in which calcium ions and / or magnesium ions are eluted may naturally flow into the drainage treatment chamber side.

In the embodiment shown in Fig. 12, the waste water from which calcium ions and / or magnesium ions are discharged is sent to the waste water treatment chamber. Therefore, by changing the water position of the discharge port of the pipe mentioned above, The concentration of calcium ions and / or magnesium ions can be easily controlled.

In the embodiment shown in Fig. 13, the ion generating source 60 is filled in a replaceable cartridge-type case, which is provided on the inflow side. With this configuration, the case can be easily detached, and maintenance such as replenishment of the ion generating source is facilitated. In the embodiments shown in Figs. 11 to 13, a pair of opposed electrodes is used. However, the present invention is not limited to this arrangement and number, and the number of electrodes on the anode side and the cathode side may be appropriately set, It can also be changed. For example, as shown in Fig. 8 (a), the electrode group 24 on the cathode side and the electrode group 25 on the anode side can be opposed to each other. Alternatively, as shown in Fig. 8 (b), the electrode 35 on the anode side and the electrode 34 on the cathode side may be arranged alternately. Further, the number of electrodes on the anode side and the number of electrodes on the cathode side may not be the same.

Next, the fourth to sixth inventions will be explained based on the embodiments, but the present invention is not limited to these embodiments.

Example 7

A test wastewater containing phosphorus ion concentration 15 mg / l or phosphorus concentration 5 mg / l (added as H ₃ PO ₄ ) and Na ⁺ 200 mg / l was taken from the inlet using an iron electrolytic dissolution drainage treatment apparatus shown in Fig. 11 at a flow rate of 1 liter / Min. ≪ / RTI > A high purity iron plate was used as the electrode to be immersed in the drainage. As the ion generating source disposed in the waste water treatment chamber, 1000 mg of CaCO ₃ was surrounded with a mesh. The amount of current to be applied to the electrode was set to 1.2 A so that Fe / P was 1.5, and the polarity was reversed every 0.5 hour.

Electrolysis of the electrodes simultaneously released iron ions and calcium ions. Since the solubility of CaCO ₃ was 15 mg / l for water at 25 ° C, the calcium ion concentration in the test water was 6 mg / l, which was over 2 mg / l.

The filtrate obtained by filtering the wastewater collected at the outlet 4 with a filter having a pore size of 0.45 탆 after energizing for 2 hours was analyzed according to the full-blown analysis method (46.3) specified in Japanese Industrial Standard K 0102. As a result, Or more.

Example 8

Except that CaCO ₃ in Example 7 was replaced by soluble Ca (OH) ₂ , the same apparatus was used under the same test conditions. The calcium ion concentration in the test drain discharged from the outlet at this time was 12 mg / l.

As a result of examination of the content of phosphorus in the same manner as in Example 7 after lapse of the energization time of half of Example 7, it was found that the removal efficiency of phosphorus was 90% or more. As the calcium ion concentration is doubled as the calcium ion concentration in Example 7 as in the present embodiment, the removal efficiency (90% or more) of phosphorus as in Example 7 can be obtained with half of the power application time. As a result, I can see that it can halve. As described above, according to the fourth to sixth aspects of the present invention, it is possible to remove phosphoric acid ions in the waste water at a high rate, and also to reduce consumption of iron or aluminum as an electrode and power for dissolving the waste water. I can drive.

Next, the seventh to eighth inventions will be described.

As shown in Fig. 14, the treatment apparatus includes a drainage treatment chamber 1 having an inlet 3 and an outlet 4 for drainage, a pair of electrodes arranged so that at least a part of the drainage in the treatment chamber 1 is immersed, And a power supply 6 for energizing the electrodes of the electrodes. The electrodes 74 and 75 may be made of platinum, gold, carbon, silver, titanium or the like. However, if the electrodes 74 and 75 are made of a metal or carbon having a low ionization tendency such as platinum or gold, The life of the electrode can be prolonged.

In the present embodiment, when electricity is applied to the electrodes 74 and 75, the liquid level around the electrode 74 on the cathode side becomes alkaline by the hydroxide ions in the drain water and the liquid level around the electrode 75 on the anode side becomes drained Gt; acid < / RTI > For this reason, pH adjustment for the reaction of CaCl ₂ or FeCl ₃ introduced into the waste water can be adjusted by the amount of current flowing between the electrodes 74 and 75 without using a pH adjusting agent. For example, in the case of a calcium ion source added to CaCl ₂ in a multiple CaCl ₂ is added from the vicinity of the electrode 74 because the alkali in the removal rate higher. The calcium ions thus eluted react with the phosphate ions in the wastewater to produce salts with water-insoluble phosphate ions.

Therefore, in the present embodiment, it is possible to omit the periodic input operation of the observation device and the pH adjuster for pH adjustment.

It is preferable that a control device 9 for controlling the current flowing between the electrodes 74 and 75 is connected to the power source 6 described above. The surface of the electrode 75 on the anode side is oxidized by an organic substance such as protein and an oxide of an inorganic substance, but the surface of the electrode 74 on the cathode side is purified by the hydrogen gas generated from the anode side and does not form an oxide film. Therefore, when the resistance between the positive electrodes 74 and 75 is increased due to the occurrence of an oxide film on the surface of the electrode 75 on the positive electrode side by the control device 9, the polarity is reversed at predetermined time intervals. As a result, the current flowing between the positive electrodes 74 and 75 can be kept substantially constant, so that the liquid material around the cathode side can be kept alkaline and the liquid material around the anode side can be kept acidic. It is preferable that the inversion time is, for example, 1 hour or more.

In the present embodiment, the source of calcium ions and / or magnesium ions is put in the vicinity of the electrode 74 on the cathode side. A reference numeral 78 in Fig. 14 is a charging device for charging such an ion generating source into waste water. When the ion generating source is a fluid such as an aqueous solution, a tank for introducing the ion generating source and a supplying means such as a metering pump for delivering the ion generating source in a quantitative manner are used, and the ion generating source is a particulate substance It is used as a feeding means for feeding the ion generating source in a quantitative manner by a hopper, a screw or the like.

There are three kinds of ion generating sources, that is, a calcium ion generating source, a magnesium ion generating source, and an ion generating source in which these are combined. As the calcium ion generating source, metal calcium or a water-soluble salt of calcium can be used. As the above magnesium ion generating source, metal magnesium or magnesium water-soluble salts can be used. Specific examples of these water-soluble salts include calcium hydroxide (solubility: 185 mg / 100 g of water), calcium carbonate (solubility: 1.4 mg / 100 g of water), magnesium chloride (solubility: 52.8 g / 100 g of water) and magnesium oxalate (solubility: 70 mg / 100 g of water). Of these, calcium chloride, calcium hydroxide and magnesium chloride are particularly preferable in that they readily dissolve in water to generate a large amount of calcium ions or magnesium ions. In the case of a salt having low solubility in water, it may be added in the form of an aqueous solution in advance.

In the embodiment shown in Fig. 14, when the electrodes 74 and 75 are energized, the periphery of the electrode 74 on the cathode side becomes alkaline, and the calcium ions (magnesium ions) eluted react with the phosphate ions in the waste water, To form insoluble salts with water.

In the embodiment shown in Fig. 14, the calcium ion and / or magnesium ion generating source is injected from the charging device 78 into the vicinity of the electrode 74 on the cathode side. However, the present invention is not limited to this, The iron ion source and / or the aluminum ion source can be supplied from the charging device 88 to the vicinity of the electrode 85 on the anode side as shown in Fig. As the iron ion generating source, a water soluble salt of iron or the like can be used. Specific examples of such water-soluble salts include ferric chloride, ferric acetate, ferric sulfate and the like.

Among them, ferric chloride is particularly preferable because it readily dissolves in water to generate a large amount of iron ions. In the case of a salt having a low solubility in water, it may be previously added in the form of an aqueous solution.

As the aluminum ion generating source, a water-soluble salt of aluminum or the like can be used. Specific examples of such water-soluble salts of aluminum include aluminum acetate and aluminum sulfate. Of these, aluminum acetate is particularly preferable in that a large amount of aluminum ions are generated by dissolving the object immediately. In the case of a salt having little solubility in water, it may be previously added in the form of an aqueous solution.

In the embodiment shown in Fig. 15, when the electrodes 84 and 85 are energized, the periphery of the electrode 85 on the anode side becomes acidic and the iron ions (aluminum ions) eluted react with the phosphate ions in the drain water, To form insoluble salts with water.

As shown in Fig. 16, a calcium ion and / or a magnesium ion generating source is charged from the charging device 98a to the vicinity of the electrode 94 on the cathode side and is supplied from the charging device 98b to the vicinity of the electrode 95 on the anode side Iron ion source and / or an aluminum ion source may be charged.

In the embodiment shown in Figs. 14 to 16, drainage of the drainage treatment chamber is constantly flowing, so that when the flow rate of the drainage water is increased, the alkaline drainage water around the electrode on the cathode side and the acid drainage water around the electrode on the anode side are easily mixed, It becomes difficult to keep the surrounding liquid material alkaline and the liquid material around the anode side acidic. Therefore, for example, as shown in FIG. 17, it is preferable to arrange the diaphragm 100 so that the alkaline drainage on the cathode side and the acid drainage on the anode side are not mixed between the positive electrodes 104 and 105. As such diaphragm 100, for example, nylon, polypropylene or the like can be used. As the arrangement of the diaphragm 100, the drainage water is disposed so as to be gentle in the vicinity of the electrodes 104 and 105 described above. Instead of the diaphragm, the flow of water may be controlled by using a partition wall made of a ceramic partition wall (alumina, zirconia) or the like.

Although the pair of opposing electrodes is used in the embodiments shown in Figs. 14 to 17, the present invention is not limited to such an arrangement and number, and the number of the electrodes on the anode side and the cathode side is appropriately set, As shown in FIG. For example, as shown in Fig. 8 (a), the electrode groups 24 on the cathode side and the electrode groups 25 on the anode side may be opposed to each other. As shown in Fig. 8 (b), the electrode 35 on the positive electrode side and the electrode 34 on the negative electrode side may be arranged alternately. In addition, the number of electrodes on the anode and cathode sides may not be the same. However, it is preferable that a diaphragm (wall) is provided between the opposing electrodes so that the acidic region and the alkaline region are not too close to each other.

Next, the seventh to eighth inventions will be described based on examples, but the present invention is not limited to these examples.

Example 9

The test wastewater containing phosphorus ion concentration of 15 mg / l or phosphorus concentration of 5 mg / l (added as H ₃ PO ₄ ) and Na ⁺ 200 mg / l was introduced from the inlet using a wastewater treatment apparatus shown in Fig. 15 at a flow rate of 1 L / . A platinum plate was used as the electrode to be immersed in the drainage. 35 mg of CaCl ₂ was added as an ion generation source in the vicinity of the electrode on the cathode side. The amount of current to be applied to the electrode was set to 1.2 A so that Ca / P was 2.0. The filtrate obtained by filtering the wastewater collected at the outlet with a filter having a pore size of 0.45 mu m after energizing for 2 hours was examined according to the full-blown analysis method (46.3) specified in Japanese Industrial Standard K 0102 and the removal efficiency of phosphorus was found to be 90% or more .

Example 10

The test wastewater containing phosphorus ion concentration of 15 mg / l or phosphorus concentration of 5 mg / l (added as H ₃ PO ₄ ) and Na ⁺ 200 mg / l was introduced at a flow rate of 1 l / min from the inlet using the wastewater treatment apparatus shown in Fig. . A platinum plate was used as the electrode to be immersed in the drainage. 39 mg of FeCl ₃ was added as an ion generating source in the vicinity of the electrode on the anode side. The amount of current to the electrode was set to 1.2 A so that Fe / P was 1.5. The content of phosphorus was examined in the same manner as in Example 9 after energizing for 2 hours. As a result, it was found that the removal efficiency of phosphorus was 90% or more.

Example 11

The test wastewater containing phosphorus ion concentration of 15 mg / l or phosphorus concentration of 5 mg / l (added as H ₃ PO ₄ ) and Na ⁺ 200 mg / l was introduced at a flow rate of 1 l / min from the inlet using the wastewater treatment apparatus shown in Fig. . A platinum plate was used as the electrode to be immersed in the drainage. Further, 7 mg of CaCl ₂ was introduced as an ion generating source in the vicinity of the electrode on the cathode side, and 31 mg of FeCl ₃ was introduced as an ion generating source in the vicinity of the electrode on the anode side. The amount of current to be applied to the electrode was set to 1.2 A such that Ca / P was 2.0 and Fe / P was 1.5.

After the lapse of half of Examples 9 to 10, the content of phosphorus was examined in the same manner as in Examples 9 to 10, and as a result, it was found that the removal efficiency of phosphorus was 90% or more at an input amount of half of the ion generating sources in Examples 9 to 10. According to the seventh to eighth inventions, pH adjustment can be facilitated, and removal of phosphate ions can be performed at low cost.

Next, the ninth to tenth inventions will be described.

A ninth aspect of the invention relates to a method of treating wastewater containing phosphoric acid ions, calcium ions and / or magnesium ions and adjusting the pH of the wastewater to 8 or more.

When phosphate ions, calcium ions and / or magnesium ions are present in the wastewater, calcium ions and / or magnesium ions react with the phosphate ions on the alkaline side to form insoluble salts in water. In the ninth to tenth inventions, phosphate ions are removed from the waste water by using calcium ions and / or magnesium ions present in the waste water. The wastewater to be treated in the ninth to tenth inventions contains phosphate ion, calcium ion and / or magnesium ion, and the concentration of these ions may be a stoichiometric amount capable of forming a salt insoluble in water It is preferable to contain 9 to 21 mg / l of phosphate ions and 6 to 23 mg / l of calcium ions and / or magnesium ions from the viewpoint of more efficient treatment.

The above-mentioned water-insoluble salts produce various types of salts such as salts and hydrates depending on the reaction conditions. Therefore, a salt insoluble in water as a salt with phosphoric acid is included in the salt of phosphoric acid, calcium, and magnesium in the present invention.

The point at which insoluble salts of such phosphate ions and calcium ions and / or magnesium ions are formed is when the drain water containing these ions is alkaline. In the ninth to tenth inventions, the water-insoluble salt The pH is adjusted to 8 or more, preferably 9 or more, in order to make it easier to form. The means for adjusting the pH of the wastewater containing phosphate ions and calcium ions and / or magnesium ions is not particularly limited, but it is preferable to add a pH adjuster in the wastewater in that the operation is easy and generally applicable to domestic wastewater .

The pH adjuster in this case is not limited as long as the pH of the wastewater can be adjusted to 8 or more, but it is preferable to use a buffer solution in view of the fact that the treatment after use is not necessary and is suitable for the environment.

The buffer may be any one capable of maintaining the pH at 8 or higher. Examples thereof include boric acid-sodium hydroxide buffer, sodium hydrogencarbonate-sodium hydroxide buffer and the like. However, sodium bicarbonate- sodium hydroxide buffer .

From another point of view, the use of Ca (OH) ₂ as a pH adjuster is preferable in that it exhibits the effect of supplementing the calcium ion source. A tenth aspect of the present invention relates to a wastewater treatment apparatus capable of performing the above-described treatment method.

As shown in Fig. 18, the wastewater treatment apparatus includes a pH meter 115 for detecting the pH of wastewater, a pH meter 115 for adding a pH adjuster to the wastewater, a wastewater treatment apparatus for wastewater containing phosphate ions, calcium ions and / And a pH adjuster 116 for maintaining the pH of the wastewater equal to or more than 8 by instructing the addition device 117 and the pH meter to have a pH of less than 8 by adding a pH adjuster to the pH adjuster addition device.

18, the apparatus for treating wastewater according to the tenth aspect of the present invention includes a stirring device 119 for stirring the wastewater 2 in a wastewater treatment tank 1 having an inlet 3 and an outlet 4 And the like. Again, the pH adjuster is supplied from the pH adjuster tank 118 into the treatment tank 1 by the pH adjuster addition device 117 in accordance with the instruction of the pH adjuster 116, but the form of the supply is not particularly limited.

Next, the treatment methods and treatment apparatuses of the ninth to tenth inventions will be described based on examples, but the present invention is not limited to such examples.

Examples 12 to 16 and Comparative Example 1

(Phosphorus ion concentration of 15 mg / l or phosphorus concentration of 5 mg / l (added as H ₃ PO ₄ ) and Ca ²⁺ (mg / l of Ca (OH)) as test wastewater by using the wastewater treatment apparatus of the tenth invention shown in Fig. ₂ ) and 10 mg? Of Mg ²⁺ (added as MgCl ₂ ) (pH 7). The above-mentioned test water was introduced at a flow rate of 1 L / hr.

As also pH adjusting agents _{(0.2MH 3 BO 3 + 0.2M KCl} ): 0.2M NaOH: water = 50: 21: to 130 (mℓ) buffer solution _{A (pH9), (0.2MH 3} BO 3 + 0.2M KCl): Buffer C (pH 11) with buffer B (pH 10), 0.05M NaHCO ₃ : 0.1M NaOH: water = 50:11:40 (mℓ), containing 0.2 M NaOH: water = 50: 44: , Buffer D (pH 12) containing 0.2 M KCl: 0.2 M NaOH: water = 25: 6: 70 (ml), 0.2 M KCl: 0.2 M NaOH: water = 25: (pH 7) containing 0.1 M Tris-aminomethane: 0.1 M HCl: water = 50: 47: 5 (ml) was used. The pH value was measured 2 hours after each buffer solution was started to flow into the test wastewater. The wastewater collected at the outlet 4 was measured for the concentration of the phosphoric acid ion in the wastewater of the treatment wastewater by filtration with a filter having a diameter of 0.45 mu m Were measured in accordance with the Japanese Pharmacopoeia (K) 0102 method (46.3). The results are shown in Table 1.

[Table 1]

Examples 17 to 21

(Water) containing 15 mg / l phosphoric acid ion concentration or 5 mg / l phosphorus concentration (added as H ₃ PO ₄ ) and 16 mg / l Ca ²⁺ added as Ca (OH) ₂ as test wastewater in Example 12 7) was used, and the concentration of phosphoric acid ions in the wastewater of the treating agent was measured in the same manner as in Example 12. [ The results are shown in Table 2.

[Table 2]

Examples 22 to 26

(PH 7) containing phosphoric acid ion concentration 15 mg / l or phosphorus concentration 5 mg / l (added as H ₃ PO ₄ ) and Mg ²⁺ 11 mg / l (added as MgCl ₂ ) And the concentration of phosphate ions in the wastewater of the treatment agent was measured in the same manner as in Example 12. < tb >< TABLE > The results are shown in Table 3.

[Table 3]

According to the ninth to tenth inventions, phosphate ions in the waste water can be efficiently removed.

The present invention is characterized in that the removal rate of phosphorus ion-containing wastewater by the electrolytic dissolution method of iron or aluminum in the phosphate ion removal method is improved and the power is saved. And the pH is easily adjusted without using a pH adjusting agent. And is characterized by efficiently and safely purifying wastewater containing phosphate ions and calcium ions and / or magnesium ions.

Claims (11)

At least one of iron ion and aluminum ion is electrochemically eluted into wastewater containing phosphate ions by using an electrode containing at least one of iron ion and aluminum ion to convert the ion of phosphorus to at least one of iron and aluminum A method for treating wastewater by flocculation in the form of a salt insoluble in water, Wherein the calcium ion concentration, the magnesium ion concentration, or the total concentration of calcium ion and magnesium ion in the wastewater to be treated is 2 mg / liter or more. At least one of iron ion and aluminum ion is electrochemically eluted into wastewater containing phosphate ions by using an electrode containing at least one of iron ion and aluminum ion to convert the ion of phosphorus to at least one of iron and aluminum A method for treating wastewater by flocculation in the form of a salt insoluble in water, Wherein at least one of a source of calcium ions and a source of magnesium ions is present in the electrode. 3. The method of claim 2, Wherein at least one of a source of calcium ions and at least one of magnesium ions and at least one source of iron ions and aluminum ions is used. An electrode 5 and an electrode 5 arranged so that a part of the drainage 2 in the treatment chamber 1 is immersed in the drainage treatment chamber 1 having an inlet 3 and an outlet 4 of the drainage 2, Characterized in that at least one of the electrodes (5) comprises at least one ion generating source of calcium ion and magnesium and at least one ion generating source of iron ion and aluminum Wherein the phosphoric acid ion-containing wastewater is treated with a phosphate ion. At least one ion of iron ion and aluminum ion is electrochemically eluted into wastewater containing phosphate ions by using an electrode containing at least one ion selected from iron ion and aluminum ions A method for treating wastewater by flocculation in the form of a salt insoluble in water, Wherein at least one of a source of calcium ions and a source of magnesium ions is present in the wastewater. 6. The method of claim 5, further comprising at least one of calcium ions and magnesium ions including at least one metal selected from the group consisting of metal calcium, metal magnesium, and compounds capable of eluting at least one of calcium ions and magnesium ions in the waste water And the source of the waste water is used. An electrode 5 disposed so as to be partially immersed in the drainage 2 in the treatment chamber 1 and an electrode 5 disposed in the drainage treatment chamber 1 having an inlet 3 and an outlet 4 of the drainage 2, And at least one of the electrodes 5 includes at least one source of iron ions and aluminum ions. In addition, at least one of the electrodes 5 is provided in front of the inlet 3, Wherein one or more sources of calcium ions and magnesium ions are disposed in the treatment tank (1). A method of treating wastewater comprising coagulating and precipitating phosphate ions in the form of a salt insoluble in water from wastewater containing phosphate ions, One or more sources of calcium ion and magnesium ion are charged in the vicinity of the cathode by supplying a direct current to one or more electrodes in the drainage, or a source of at least one of iron ion and aluminum ion in the vicinity of the anode And the water is introduced into the water tank. The method according to claim 8, wherein the diaphragm (100) or the partition is disposed between the anode and the cathode. At least a pair of electrodes 5 arranged so as to be partially immersed in the drainage 2 in the treatment chamber 1 and a drainage treatment chamber 1 having an inlet 3 and an outlet 4 of the drainage 2, And a power source 6 for energizing the pair of electrodes 5. When the pair of electrodes 5 are energized, at least one of the calcium ion and magnesium ion generating source input devices and the near- , And at least one of a source introduction device of at least one of iron ion and aluminum ion is provided in the vicinity of the anode. 11. The apparatus for treating wastewater according to claim 10, wherein a diaphragm (100) or a partition is disposed between the anode and the cathode.

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