JP2006175398A - Water treatment method and water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method and a water treatment apparatus which enable an efficient treatment of water to be treated while reducing a running cost. <P>SOLUTION: A treatment substance where an electromotive force has been induced in a magnetic field is thrown into the water to be treated to change the magnetic field applied to the treatment substance with time. For example, aeration is carried out in the water to be treated to treat material to be reacted in the water to be treated. Especially the treatment is easily achieved by generating an electromotive force, exceeding the oxidation-reduction potential of the material to be reacted in the water to be treated, in the treatment substance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention electrically treats water to be treated containing nitrogen compounds such as organic matter, organic nitrogen, nitrogen nitrite, nitrate nitrogen, and ammonia nitrogen and reactants containing phosphorus compounds such as phosphoric acid and phosphate ions. The present invention relates to a water treatment method and a water treatment apparatus for chemical treatment.

  It has been well known that nitrogen compounds are one of the causes of eutrophication of rivers and lakes. In addition, this nitrogen compound is present in a large amount in domestic household wastewater and factory wastewater, but it is difficult to purify and no effective measures can be taken. In general, biological treatment is performed. First, it is performed by two steps, a nitrification step for converting ammonia nitrogen to nitrate nitrogen and a denitrification step for converting nitrate nitrogen to nitrogen gas. Two reaction vessels are required, and the processing time is long, so that there is a problem that the processing efficiency is lowered.

  In addition, in the biological treatment, a large-capacity anaerobic tank is required to hold nitrifying bacteria and denitrifying bacteria, and there is a problem that the equipment construction cost increases and the installation area of the apparatus increases. Furthermore, since these nitrifying bacteria and denitrifying bacteria are significantly affected by the ambient temperature environment and other components contained in the water to be treated, the activity decreases and the denitrifying action particularly in winter when the temperature is low. As a result, the processing efficiency becomes unstable.

  Therefore, in order to solve the above technical problem, there is a method in which ammonia, nitrite nitrogen, and nitrate nitrogen are oxidized or reductively decomposed into nitrogen gas by passing an electric current through the water to be treated (for example, patents). Reference 1). In this case, the treatment is performed electrochemically by immersing the electrode serving as the anode and the electrode serving as the cathode in the water to be treated and passing a predetermined current through them.

  In addition to this, as a method for treating sludge formed from, for example, microbial flocs in the treated water, magnetic powder is added and mixed in the treated water, and the treated water is magnetically treated to produce floc. There is a method of aggregating and solid-liquid separation (for example, see Patent Document 2). Further, in Patent Document 2, there is a processing method shown in Patent Document 3 as an aggregating method in which another aggregating agent is added prior to addition of magnetic powder.

The coagulation treatment method is performed by adding an aggregating agent to the water to be treated, allowing the water to be treated to pass through a fluidized bed containing magnetized magnetic powder, and capturing and separating the coagulated flocs. Ferric chloride or the like is used as the flocculant.
JP 2000-117259 A JP-A-48-42570 JP 11-57310 A

  In both of the methods for treating water to be treated according to Patent Document 2 and Patent Document 3 described above, an object to be treated such as microorganisms in the water to be treated is formed with agglomerated flocs using magnetic powder, and the agglomerated flocs are separated to separate Treats treated water. However, in this method, since the object to be treated in the water to be treated is separated by agglomeration, a large amount of flocs to be separated are generated, and there is a problem that the flocs after separation must be further processed.

  Moreover, in the said method, since the circumference | surroundings of magnetic body powder will be covered with organic substance, it cannot anticipate using the physicochemical reaction in a magnetic body surface.

  Therefore, there is a method of converting ammonia nitrogen in the water to be treated by oxidation or reductive decomposition into nitrogen gas by electrochemically treating the water to be treated as in the invention described in Patent Document 1. In the method, since it is necessary to immerse the electrode in the water to be treated and apply a predetermined potential, a large amount of power consumption is required for the treatment, and there is a problem that the running cost increases. Also, depending on handling, there is a risk of explosion. Therefore, in addition to the advancement of electrochemical treatment, development of a cheaper and safer treatment method is desired.

  Accordingly, the present invention has been made to solve the conventional technical problems, and provides a water treatment method and a water treatment apparatus that can effectively treat water to be treated while reducing running costs. The purpose is to do.

  In the water treatment method of the present invention, a treatment substance that generates an induced electromotive force in a magnetic field is introduced into the treatment water, the treatment substance moves in the magnetic field, and the magnetic flux that the treatment substance passes is changed. It is characterized by treating a reaction substance in the treated water.

  According to the water treatment method of the invention of claim 2, in the above invention, an electromotive force that is lower than the oxidation-reduction potential of the reaction substance in the water to be treated, or more noble, or more noble and more noble in the treatment substance. It is characterized by generating.

  According to the water treatment method of the invention of claim 3, in each of the above inventions, the treatment substance is moved in a static magnetic field, or the magnetic flux passing through the treatment substance is temporally changed by changing the magnetic field itself. Features.

  A water treatment method according to a fourth aspect of the present invention is characterized in that, in each of the above inventions, a plurality of types of treatment substances having different rest potentials are introduced into the water to be treated.

  The water treatment method of the invention of claim 5 is characterized in that, in each of the above inventions, iron oxide is used as a treatment substance.

  The water treatment method of the invention of claim 6 is characterized in that, in the above invention, the treatment substance is iron (III) oxide, and the water to be treated is irradiated with light.

  The water treatment method of the invention of claim 7 is characterized in that, in each of the above inventions, chloride ions are introduced into the water to be treated.

  The water treatment apparatus according to an eighth aspect of the present invention includes a treatment substance that is introduced into water to be treated and generates an induced electromotive force in a magnetic field, and an action unit that moves the treatment substance in the magnetic field. And

  In the water treatment apparatus of the invention according to claim 9, in the above invention, the action means generates an electromotive force that is lower than the oxidation-reduction potential of the reactant in the water to be treated, or more noble, more base, and more noble. It is generated in a treated substance.

  The water treatment apparatus according to claim 10 is the water treatment apparatus according to the invention, wherein the action means moves the treatment substance in a static magnetic field or changes the magnetic field itself to pass the treatment substance. It is characterized by changing the time.

  The water treatment device according to an eleventh aspect of the present invention is characterized in that, in each of the above water treatment devices, a plurality of types of the treatment substances having different rest potentials are introduced into the water to be treated.

  A water treatment device according to a twelfth aspect of the present invention is the invention of each of the water treatment devices described above, wherein the treatment substance has a fine size and a plurality of treatment substances are introduced into the water to be treated, and includes a filtering means for filtering the water to be treated. The action means includes a magnetic field generating means for generating a static magnetic field in the water to be treated and a stirring means for stirring the water to be treated.

  A water treatment device according to a thirteenth aspect of the invention is characterized in that, in the invention of each of the water treatment devices, the treatment substance uses iron oxide.

  The water treatment device according to the invention of claim 14 is characterized in that, in the above invention, the treatment substance is iron (III) oxide, and comprises light generating means for irradiating light into the water to be treated.

  According to the water treatment method of the present invention, a treatment substance that generates an induced electromotive force in a magnetic field is introduced into the water to be treated, and the treatment substance moves in the magnetic field, thereby using the induced electromotive force induced. It becomes possible to electrochemically treat the reaction substance in the for-treatment water.

  In particular, by generating an electromotive force in the treatment substance as in the invention of claim 2 that is lower than the oxidation-reduction potential of the reaction substance in the water to be treated, or more noble, or both base and more noble. Redox treatment of the reactant is possible. Therefore, for example, when the substance to be treated in the water to be treated is nitrate nitrogen or ammonia nitrogen, the nitrate nitrogen or ammonia nitrogen is oxidized and reduced to be treated to harmless nitrogen gas. Is possible.

  Thereby, it becomes possible to realize a high processing capability of the reactant. In addition, according to the present invention, it is not necessary to apply a predetermined potential to the electrodes as in the prior art, and usually the reaction is promoted by using agitation necessary for improving the processing efficiency. Reduction can be achieved, and safety in processing can be ensured.

  According to the invention of claim 3, in each of the above-described inventions, in order to change the magnetic flux passing through the processing material by moving the processing material in a static magnetic field or by changing the magnetic field itself, The magnetic field can be temporally changed with a simple configuration, and the structure of the device for realizing the present invention can be simplified.

  According to the invention of claim 4, in each of the above inventions, by introducing a plurality of types of treatment substances having different rest potentials into the treated water, an oxidation-reduction potential corresponding to the treatment substance can be realized, and The induced electromotive force according to the treatment substance can realize base, noble, or both from the plurality of oxidation-reduction potentials. Therefore, it is possible to reduce, oxidize, or oxidize and reduce the substance to be treated. Become.

  According to the invention of claim 5, in each of the above inventions, by using iron oxide as a treatment substance, the iron oxide having a negative rest potential is given a time-varying magnetic field as in the invention of claim 1. Thus, a reduction reaction of nitrate nitrogen and an oxidation reaction of chloride ions can be caused by the induced electromotive force.

  Further, the iron oxide generates iron when the potential reaches the reduction potential of iron oxide at the cathode formed by polarization by induced electromotive force. On the other hand, when the potential reaches the oxidation potential of iron in the anode formed by polarization, iron dissolution occurs. In combination with oxidation of the dissolved iron, iron phosphate can be formed by reacting with phosphate ions in the water to be treated together with the reduction reaction of nitrate nitrogen.

  According to the invention of claim 6, in the above invention, the treatment substance is iron (III) oxide, and the iron oxide (III) that irradiates light into the treated water is used as a photocatalyst to oxidize organic matter in the treated water. As a result, the nitrogen and phosphorus removal treatment can be performed.

  According to the invention of claim 7, in each of the above inventions, by introducing chloride ions into the water to be treated, an oxidizing agent such as hypochlorous acid can be generated with high efficiency in the water to be treated. It becomes like this. As a result, denitrification treatment of ammonia and the like produced at the cathode formed on each treatment substance by the induced electromotive force can be performed by an oxidizing agent such as hypochlorous acid produced in the water to be treated. . Therefore, nitrogen components such as nitrate nitrogen, ammonia nitrogen, and nitrogen compounds can be treated more effectively.

  In addition, when the treatment substance is iron oxide, the passive oxide film formed on the iron oxide can be destroyed with chloride ions, so that iron dissolution can be promoted and the effect is further improved. Thus, it becomes possible to treat the reaction substance.

  According to the water treatment device of the invention of claim 8, since the treatment substance is introduced into the treated water and generates an induced electromotive force in the magnetic field, and the action means for moving the treatment substance in the magnetic field, By using the induced electromotive force induced by the time change of the magnetic field, it becomes possible to electrochemically treat the reaction substance in the for-treatment water.

  In particular, the action means as in the invention of claim 9 causes the treatment substance to generate an electromotive force that is lower than the oxidation-reduction potential of the reaction substance in the water to be treated, or more noble, or both lower and more noble. As a result, it becomes possible to perform oxidation-reduction treatment of the reactant. Therefore, for example, when the substance to be treated in the water to be treated is nitrate nitrogen or ammonia nitrogen, the nitrate nitrogen or ammonia nitrogen is oxidized and reduced to be treated to harmless nitrogen gas. Is possible.

  Thereby, it becomes possible to realize a high processing capability of the reactant. In addition, according to the present invention, it is not necessary to apply a predetermined potential to the electrodes as in the prior art, and usually the reaction is promoted by using agitation necessary for improving the processing efficiency. Reduction can be achieved, and safety in processing can be ensured.

  According to the invention of claim 10, in the invention of each water treatment apparatus described above, the action means moves the treatment substance in a static magnetic field, or changes the magnetic field itself to pass the treatment substance through the magnetic flux. By temporally changing the magnetic field, the magnetic field can be temporally changed with a simple configuration, and the structure of the apparatus can be simplified.

  According to the invention of claim 11, in the inventions of the respective water treatment apparatuses, since a plurality of types of the treatment substances having different rest potentials are introduced into the water to be treated, the oxidation-reduction potential corresponding to the treatment substance In addition, the induced electromotive force according to the treatment substance can realize base, noble, or both from the plurality of oxidation-reduction potentials. Therefore, the substance to be treated is reduced, oxidized, or oxidized and It can be reduced.

  Further, according to the invention of claim 12, in the invention of each of the above water treatment apparatuses, the treatment substance has a fine size and a plurality of treatment substances are introduced into the water to be treated, and a filtering means for filtering the water to be treated is provided. Since the action means is composed of a magnetic field generating means for generating a static magnetic field in the water to be treated and an agitating means for stirring the water to be treated, the magnetic field generating means applies a magnetic field to the processing substance having a fine dimension. In addition, by stirring the water to be treated by the stirring means, a magnetic flux that changes with time can be given to the treated substance, and each treated substance can obtain an induced electromotive force unique to each treated substance.

  As a result, each treatment substance is polarized by the induced electromotive force and forms a cathode and an anode, respectively, thereby causing a reduction reaction of nitrate nitrogen present in the water to be treated and an oxidation reaction of chloride ions. Can do.

  In particular, since the processing substance is formed in a fine size, it can be easily accelerated by the stirring means, and the induced electromotive force generated in each processing substance can be increased by increasing the speed of the processing substance. Will be able to.

  Moreover, since the to-be-processed water is provided with the filtration means, it becomes possible to avoid the inconvenience that the processing substance having a fine dimension is discharged together with the to-be-processed water to be processed. Thereby, the maintenance work can be simplified and the cost can be reduced.

  According to the invention of claim 13, in the invention of each water treatment apparatus, the treatment substance uses iron oxide, so that the iron oxide having a negative rest potential changes over time as in the invention of claim 7. By applying a magnetic field, the induced electromotive force can cause a reduction reaction of nitrate nitrogen and an oxidation reaction of chloride ions.

  Further, the iron oxide generates iron when the potential reaches the reduction potential of iron oxide at the cathode formed by polarization by induced electromotive force. On the other hand, when the potential reaches the oxidation potential of iron in the anode formed by polarization, iron dissolution occurs. In combination with oxidation of the dissolved iron, iron phosphate can be formed by reacting with phosphate ions in the water to be treated together with the reduction reaction of nitrate nitrogen.

  According to the invention of claim 14, in the above invention, the treatment substance is iron (III) oxide, and the light generation means for irradiating light into the water to be treated is provided. As a result, it is possible to oxidize and decompose organic substances in the water to be treated, and to perform nitrogen and phosphorus removal treatment.

  First, the basic principle of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram of an induced electromotive force, FIG. 2 is a diagram showing a rest potential state of a treatment substance (carrier), and FIGS. 3 to 5 are redox potentials (oxidation reduction potential) of the treatment substance (carrier). FIG.

As shown in FIG. 1, a treatment substance (hereinafter referred to as a carrier) S is present in a predetermined magnetic field, and the induced electromotive force e is changed by temporally changing the position of the carrier S at a predetermined speed v. appear. A formula for calculating the induced electromotive force is shown in Formula 1.
Formula 1 e = vBl
In the formula, B is the magnetic flux density that passes through the carrier S, and l indicates the length of the carrier.

  The carrier S has a predetermined rest potential according to the material constituting the carrier S as shown in FIG. Therefore, an anode having a positive or near positive potential is formed on one side of the carrier S, and a cathode having a negative or near negative potential is formed on the other side. By causing the carrier S to exist in the magnetic field as described above and changing the position of the carrier S with time at a predetermined speed v, a dielectric electromotive force e is generated in the carrier S.

  As a result, the carrier S is further polarized by electromagnetic induction to form an anode having a more positive or near positive potential and a cathode having a more negative or near negative potential. For example, as shown in FIG. 3, the carrier S (treated particles) has a positive rest potential, induces an electromotive force in the carrier S, forms an anode at one end, and forms a cathode at the other end. . At this time, there is a reactant in the treated water to which the carrier S is added, and the oxidation-reduction potential generated at the anode is more noble than the redox potential (oxidation-reduction potential) of the reactant, If it is positive, an oxidation reaction of the reactant can be caused in the anode generated in the carrier S. Examples of those having a positive rest potential include copper, platinum, gold, manganese oxide, and palladium.

  On the other hand, as shown in FIG. 4, the carrier S (treated particles) has a negative rest potential, induces an electromotive force in the carrier S, forms an anode at one end, and forms a cathode at the other end. . At this time, when the target substance exists in the target water to which the carrier S is added, and is lower than the redox potential generated at the cathode than the redox potential of the target substance, that is, negative. The reduction reaction of the reactant can be caused at the cathode generated on the carrier S. Examples of such a negative rest potential include iron.

  Further, as shown in FIG. 5, an electromotive force is induced by moving the carrier S in a magnetic field, and an anode is formed at one end and a cathode is formed at the other end. At this time, when the carrier S is composed of a plurality of types of substances having different oxidation-reduction potentials and a plurality of types of the reactants are present in the added treated water, the anode is more than the redox potential of the reactants. When the oxidation-reduction potential generated in the step is more noble, that is, positive, an oxidation reaction of the reactant can be caused in the anode generated in the carrier S. In addition, when the redox potential at the cathode generated in the carrier S is more base, that is, negative than the redox potential of the reactant, a reduction reaction of the reactant can be caused at the cathode. As described above, a substance capable of generating a positive and negative induced electromotive force e generated in the carrier S and generating a predetermined potential at each anode and cathode can cause a redox reaction at both the anode and the cathode. It becomes. Further, as a combination of a plurality of carriers S, it is possible to have one side carry out oxidation and the other carry out a reduction reaction. An example of such a substance is a combination of platinum and iron.

  Therefore, if the carrier S generates an induced electromotive force by moving it in a magnetic field, the present invention can be realized. That is, even if it is a nonmagnetic material such as aluminum or a paramagnetic material such as iron (III) oxide (hematite), the present invention can be realized as long as it absorbs magnetic flux.

  Next, an example of an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 6 is an explanatory view showing an outline of the waste water treatment apparatus 1 for realizing the method for treating waste water as the water to be treated according to the present invention. The wastewater treatment apparatus 1 in this embodiment is for treating wastewater containing nitrogen compounds, phosphorus compounds, etc., including nitrate nitrogen, ammonia nitrogen, etc., and particularly in this embodiment, from pig farms, etc. It treats discharged wastewater.

  The wastewater treatment apparatus 1 includes a treatment tank 2 that forms a treatment chamber 4 having a drainage inlet and an outlet (not shown) inside, and a magnetic field that generates a static magnetic field in the wastewater stored in the treatment tank 2. Permanent magnet 3 as generating means, a plurality of microporous thin films 24 as filtering means disposed in the treatment tank 2, and a suction pump 26 for pumping up the waste water filtered by the microporous thin film 24 And a blower 28 for providing a swirling flow to the microporous thin film 24 and a light irradiation device 6 for irradiating visible light into the waste water in the processing chamber 4. .

In the wastewater stored in the processing chamber 4, a predetermined amount of the carrier S as the processing substance as described above is charged. In this embodiment, the carrier S is composed of iron oxide (ferrous iron oxide (III) iron (II) (Fe ₃ O ₄ ), iron oxide (paramagnetic iron oxide (III) (Fe ₂ O ₃ ), and Platinum (Pt) is introduced into the waste water in the processing chamber 4 as fine particles of about 1 micron, for example.

  The microporous thin film 24 is a submerged flat film, and is composed of film bodies 30 and 30 forming front and rear surfaces and a frame body 33 surrounding the film bodies 30 and 30 as shown in FIG. Has been. Spacers 32 and 32 and a support body 34 are formed inside the film bodies 30 and 30. In addition, a water collection outlet 36 for communicating with the membrane bodies 30 and 30 and for connecting to the suction pump 26 is formed on the upper portion of the frame 33.

  Here, the membrane body 30 is a membrane member in which micropores having a predetermined diameter or less are formed, and prevents the movement of the carrier S in this embodiment, oil, fine particles, bacteria, and the like contained in the waste water, and only moisture. Can be transmitted. As a result, the carrier S, oil, fine particles, bacteria, and the like in the wastewater are separated by the membrane body 30, and only the water sucked into the membrane body 30 enters the water collection outlet 36 formed on the top of the microporous thin film 24. Reach.

  The blower 28 provided at the lower portion of the processing tank 2 supplies air bubbles into the processing tank 2. The bubbles move the carrier S accommodated in the treatment tank 2 at a speed v and increase the number of collisions between each carrier S and a reactant such as nitrate nitrogen, ammonia nitrogen, and phosphorus compound in the waste water. To promote the electrochemical reaction in the carrier S.

  Further, the bubbles supplied into the waste water by the blower 28 become a swirling flow, and the fine particles adhering to the surface of the microporous thin film 24 are aerated and washed. As a result, while the microporous thin film 24 is aerated and washed, only the water in the waste water is sucked and passed through the film body 30, so that stable filtration treatment can be performed while suppressing the blocking of the micropores in the film body 30. It can be carried out. As a result, it is possible to operate for a long time in high-concentration waste water, and it is possible to improve the filtration efficiency.

  On the other hand, the suction pump 26 is connected to a drain pipe for draining the waste water sucked into the membrane body 30 and collected at the water collection outlet 36 formed on the upper portion of the microporous thin film 24 to the outside. .

  Further, the light irradiation device 6 is a device that irradiates the wastewater accommodated in the treatment tank 2 with visible light, and is visible to the carrier S accommodated in the treatment tank 2, particularly iron (III) oxide. , The iron (III) oxide is used as a photocatalyst, and the organic matter in the wastewater is oxidatively decomposed.

  A plurality of the permanent magnets 3 are provided, for example, at positions facing each other through the treatment tank 2. In the wastewater stored in the treatment tank 2 located between the permanent magnets 3, 3, for example, magnetic flux A static magnetic field having a density of 10 mT is generated.

With the above configuration, by operating the blower 28 in a state where a predetermined amount of the carrier S and waste water are stored in the treatment tank 2, a swirl flow due to bubbles is generated in the waste water as described above. As a result, since the carrier S moves in the static magnetic field, an electromotive force is induced on the carrier S, and as shown in FIG. 8, the iron oxide constituting the carrier S is induced from the rest potential state (upper left of FIG. 8). When electromotive force is generated, polarization occurs, Fe is reduced from Fe ₃ O _{4 at} one end of each support S (lower left in FIG. 8), and further, an anode is formed on the side reduced to Fe. On the other hand, a cathode is formed, and the potential generated in the carrier S is more positive than the oxidation potential of Fe, so that Fe is oxidized, whereby iron (II) ions (Fe ²⁺ ) are generated from the anode of the carrier S. It will elute into the waste water.

Then, in the waste water, the reactions as shown in FIG. 9 occur, whereby nitrate nitrogen and phosphorus compounds in the waste water are treated. That is, iron (II) ions eluted in the waste water are oxidized to iron (III) ions in the waste water (reaction A).
Reaction A Fe ²⁺ → Fe ³⁺ + e ⁻

At this time, the electromotive force induced in the iron oxide as the carrier S is larger than the redox potential of nitrate ion and the nitrite ion as the reactants in the waste water in this embodiment. Therefore, on the cathode side of the carrier S, electrons released on the anode side are supplied, and a reaction for reducing nitrate ions as nitrate nitrogen contained in the waste water to nitrite ions occurs (reaction B). Further, the nitrate nitrogen reduced to nitrite ions is supplied with electrons on the cathode side of the carrier S and is reduced to ammonia (ammonium ions) (reaction C). Reaction B and reaction C are shown below.
Reaction B NO ₃ ⁻ + H ₂ O + 2e ⁻ → NO ₂ ⁻ + 2OH ⁻
Reaction C NO ₂ ⁻ + 5H ₂ O + 6e− → NH ₃ (aq) + 7OH ⁻

On the other hand, since platinum is also used as the carrier S in the waste water, an electromotive force is induced in the platinum as the carrier S in the same manner as iron oxide. Since the electromotive force induced in the platinum has a magnitude exceeding the redox potential of chloride ions as the reactants in the waste water, it is shown in FIG. 10 on the anode side of the support S composed of platinum. Thus, a reaction occurs in which chloride ions release electrons to generate chlorine. Furthermore, the chlorine produced | generated in waste water melt | dissolves in water, and produces | generates hypochlorous acid (reaction D). In this example, since chloride ions are contained in the waste water, hypochlorous acid is generated, but when other halide ions are contained in the waste water in addition to this, Even if other hypohalous acid such as hypofluoric acid or hypobromous acid is generated, the same effect is obtained.
Reaction D 2Cl ⁻ → Cl ₂ + 2e ⁻
_{Cl 2 + H 2 O → HClO} + HCl

  Here, when the concentration of chloride ions contained in the wastewater is low, for example, potassium chloride or the like may be added as a compound containing chloride ions in the wastewater.

As described above, the chlorine produced in the carrier S composed of platinum dissolves in water, so that hypochlorous acid is sharpened. The hypochlorous acid is converted into ammonia produced in the waste water in the reaction C. After reacting with (ammonium ion) and undergoing a plurality of chemical changes, it is converted into nitrogen gas (reaction E).
Reaction E NH ₃ + HClO → NH ₂ Cl + H ₂ O
NH ₂ Cl + HClO → NHCl ₂ + H ₂ O
NH ₂ Cl + NHCl ₂ → N ₂ ↑ + 3HCl

  Thereby, nitrogen compounds, such as nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen, which are contained in the waste water, can be treated by the induced electromotive force generated in the carrier S.

On the other hand, in the case where phosphate ion as a phosphorus compound is contained in the wastewater, in the reaction A, a dephosphorization reaction occurs as shown in the reaction F with the generated iron (III) ion, so that Coagulates and precipitates with phosphate ions to produce iron phosphate that is sparingly soluble in water.
Reaction F Fe ³⁺ + PO ₄ ^3- → FePO ₄ ↓
Thereby, the phosphate ion as a phosphorus compound contained in the waste water can be precipitated as iron phosphate.

  Further, in order to supply electrons, some of the iron (III) ions eluted in the state of iron (II) ions in the waste water and oxidized in the waste water are supported by the carrier S which is composed of iron oxide in this case. On the cathode side formed by induced electromotive force, electrons are supplied again, reduced to iron (II) ions, and oxidized again on the anode side.

  As described above, nitrogen compounds such as nitrate nitrogen, nitrite nitrogen, ammonia nitrogen and phosphorus compounds in the wastewater stored in the treatment tank 2 are treated electrochemically by the electromotive force induced in the carrier S. Is done. Here, since the microporous thin film 24 as a filtering means as described above is provided in the treatment tank 2, the waste water after being treated by the suction pump 26 is oiled by the microporous thin film 24. After separating the particles, bacteria, and further the carrier S, only the water sucked into the film body 30 is discharged to the outside through the water collection outlet 36.

  For this reason, it is possible to avoid the inconvenience that the carrier S having a fine dimension is discharged together with the waste water after the treatment. Thereby, the maintenance work can be simplified and the cost can be reduced.

  Thus, according to the present embodiment, an electromotive force can be induced in the carrier S by moving the carrier S at a certain speed in a static magnetic field, and using the induced electromotive force, nitric acid in waste water can be induced. It becomes possible to electrochemically treat nitrogen and ammonia nitrogen. In particular, in the present embodiment, since iron oxide having a negative rest potential is used as the carrier S, it is possible to generate an electromotive force exceeding the redox potential of nitrate nitrogen or ammonia nitrogen. Electrochemical treatment by induced electromotive force can be realized. Therefore, it becomes possible to realize a high treatment capacity such as nitrate nitrogen and nitrite nitrogen in the waste water.

  In particular, as a means for moving the carrier S at a certain speed, it is possible to share the blower 28 as a stirring means for removing the substance adhering to the microporous thin film 24 as described above with water bubbles. Therefore, normally, the processing capability of the carrier S can be improved by utilizing a stirring means necessary for improving the processing efficiency by the microporous thin film.

  Further, the iron oxide generates iron when the potential reaches the reduction potential of iron oxide at the cathode formed by polarization by induced electromotive force. On the other hand, when the potential reaches the oxidation potential of iron in the anode formed by polarization, iron dissolution occurs. In combination with oxidation of the dissolved iron, iron phosphate can be formed by reacting with phosphate ions in the water to be treated together with the reduction reaction of nitrate nitrogen.

  Further, in this embodiment, chloride ions are present in the water to be treated, or chloride ions are added as described above. Therefore, the chloride ions are formed on the support S, for example, the iron surface by the chloride ions. It becomes possible to destroy the passive film, and to promote iron dissolution.

  As a result, when nitrate nitrogen or phosphate ions are contained in the wastewater as the reactants, the induced electromotive force generated in the iron oxide can effectively perform oxidation / reduction treatment, It becomes possible to realize advanced water treatment.

  Incidentally, the iron (III) oxide used as the carrier S can act as a photocatalyst by being irradiated with visible light by the light irradiation device 6 as in the present embodiment, whereby the organic matter in the wastewater can be obtained. Can be oxidized and decomposed.

  In the present invention, it is not necessary to apply a predetermined potential to the electrodes as in the prior art, and the reaction is promoted by using a normally required stirring means, so that the running cost can be reduced and the safety in processing can be reduced. Can be secured.

  Furthermore, in this embodiment, since the carrier S is composed of fine particles of about 1 micron, it is possible to easily move the carrier S at a predetermined speed or more by the generation of bubbles by the blower 28. The induced electromotive force generated in the carrier S can be easily increased.

  In the present embodiment, an induced electromotive force is generated in the carrier S by moving the carrier S at a certain speed in a static magnetic field. However, in addition to this, the carrier S is stationary or moved to generate a magnetic field. An induced electromotive force may be generated in the carrier S by changing the generated permanent magnet itself with a motor or the like or using an electromagnet.

  In the present embodiment, since iron oxide and platinum having different rest potentials are used as the carrier S, it is possible to obtain different induced electromotive force values. It becomes possible to cope with the potential, and smooth processing can be realized.

Below, the experimental result about the processing capacity of the waste_water | drain by the induced electromotive force of this invention is shown. The drainage sample used in the experiment was prepared by mixing 100 mM potassium chloride, 10 mM potassium nitrate, and 10 mM potassium dihydrogen phosphate. Further, as the carrier S, 0.3 to 0.4 g of two different types of ferrite powders, Fe ₃ O ₄ (magnetite) and NiFeO ₄ were used for the drainage sample, respectively. All ferrite powders having a particle size of about 1 μm were used.

  In this experiment, as shown in FIG. 11, the drainage sample and the carrier S accommodated in a predetermined container 12 were respectively arranged on the rotating shaft 10 </ b> A of the motor 10 between the permanent magnets 3 and 3. As the permanent magnet 3, a TM-YSV5509C-031 type (manufactured by Tamagawa Seisakusho) with a variable gap interval was used, and the gap interval was 50 mm, and the one that generated 3.23 kOe at 10 A, the maximum current, was used. In this experiment, 8A was passed through the coil, the drainage sample container 12 was placed outside the center and the coil, and the motor 10 was rotated about 900 per minute for 1 to 3 hours. The central magnetic flux density B1 at the center is 250 mT, and the central magnetic flux density B2 outside the coil is 10 mT. After the treatment, the mixture was centrifuged at 12000 rpm for 1 minute in a microcentrifuge to obtain a supernatant, and the phosphorus component contained in the supernatant was measured by a colorimetric method, and the nitrogen component was measured by ion chromatography.

FIG. 12 is a diagram showing the relationship between the phosphorus removal rate and the magnetic flux density when Fe ₃ O ₄ (magnetite) is used as the carrier S. According to this, when there is no carrier S and the magnetic flux density is 0 mT, the phosphorus removal rate is about 13%, and when there is no carrier S and the magnetic flux density is 250 mT, the phosphorus removal rate is about 30%. It was. When the carrier S was present and the magnetic flux density was 250 mT, the phosphorus removal rate was about 82%. Thereby, it can be seen that the phosphorus compound in the drainage sample can be removed regardless of the presence of the carrier S. However, it can be seen that the presence of the magnetic field and the carrier S in the drainage sample increases the phosphorus removal rate several times. Thereby, it turns out that the phosphorus removal rate improves by making the support | carrier S exist in the magnetic field which changes temporally.

The reason why phosphorus is removed even when there is no temporally changing magnetic field or carrier S is that SS settles down by the centrifugal treatment after the treatment. The improvement of the phosphorus removal rate by the magnetic field treatment in the absence of the carrier S is due to the formation of polarization by causing a magnetic field change in the carrier S such as a magnetic substance originally contained in the waste water or a metal component, or the generation of an electric current. This is thought to be because adsorption or the like occurred. This can also be inferred from the fact that the phosphorus removal rate is improved by adding Fe ₃ O ₄ as the carrier S.

FIG. 13 is a diagram showing the influence of chloride ions on the phosphorus removal rate. According to this, the phosphorus removal rate is about 3.8% when KH ₂ PO ₄ in the drainage sample is 200 mM and KCl is not added and the same experiment as described above is performed at a magnetic flux density of 10 mT. It was. When the same experiment as described above was performed at a magnetic flux density of 0 mT in which KH ₂ PO ₄ in the wastewater sample was 200 mM and KCl was not added, the phosphorus removal rate was about 3.0%. On the other hand, the phosphorus removal rate was about 24.8% when KH ₂ PO ₄ in the wastewater sample was 10 mM and KCl was added at 100 mM and the experiment similar to the above was performed at a magnetic flux density of 10 mT. . In this case, substantially the same result was obtained when KH ₂ PO ₄ was 200 mM.

  Thus, it can be seen that phosphorus cannot be almost removed unless chloride ions coexist. In general, it is known that a passive film formed in an oxidizing atmosphere and functioning to prevent dissolution of iron is destroyed by chloride ions, resulting in iron corrosion. Therefore, the removal of phosphoric acid only in the presence of chloride ions means that iron phosphate with iron elution from the iron surface generated as a result of chloride ion coating attack other than removal by SS adsorption in organic matter. It can be seen that formation is a reasonable removal mechanism.

FIG. 14 is a view showing the relationship between the phosphorus removal rate and the nitric acid removal rate and the ferrite constituent metals. According to this, when Ni—Fe ₂ O _{4 in} which Fe ₃ O ₄ is partially substituted with Ni (nickel) is used as the carrier S, the phosphorus removal rate is about 28.5%, and the nitric acid removal rate is about 10 It was 6%. In contrast, when Fe ₃ O ₄ was used as the carrier S, the phosphorus removal rate was about 50%, and the nitric acid removal rate was about 9.4%.

  Thereby, it turns out that there is a correlation between the composition ratio of iron and the phosphorus removal rate, and this also confirms that phosphorus removal is caused by iron dissolution. In each case, nitric acid was treated at about 10%.

  Based on the above experimental results, it can be seen that the treatment of phosphorus compounds and nitrogen compounds in waste water by the carrier S that generates an induced electromotive force in a time-varying magnetic field of the present invention is effective. Since the present invention can remove the phosphorus compound if there is a mechanism for moving the carrier S, for example, a mechanism for flowing or moving waste water, it is possible to eliminate the need for a power source and wiring as in the prior art. Therefore, it is possible to construct a low-cost wastewater treatment system.

  In the present embodiment, as described above, the support S is most suitable, for example, iron oxide containing a large amount of iron as described above. However, the present invention is not realized using magnetization. Not only a ferromagnetic material but also a material having a non-zero magnetic permeability can be realized. However, higher permeability is more preferable because the induced electromotive force increases.

  In addition, by eluting iron excessively with respect to the amount of phosphorus compound in the treated water, hypochlorite ions generated in the treated water by the excessive iron (II) ions are converted into chloride ions. It becomes possible. This makes it possible to achieve removal of hypochlorous acid in the water to be treated, so that the treated water after treatment can be discharged into the environment without any special means for removing hypochlorous acid. It becomes possible.

  Further, in this embodiment, as described above, since the surface of the carrier S and iron ions dissolved from the carrier S are used for the treatment of the reactant, there is no need for a flocculant or the like. In addition, it becomes possible to electrochemically decompose the reactants in the water to be treated. Further, depending on the form of treatment, when organic matter or the like in the water to be treated is attracted by the magnetic force generated on the carrier S, the surface of the carrier S is covered with the organic matter and the reaction field is reduced. In some cases, it may be desirable to configure the carrier S with a paramagnetic material. In addition, when the support S is completely covered with an organic substance or the like, there is no reaction field with the substance to be reacted. For example, when the water to be treated is sludge, filtration treatment is performed. For example, by performing the pretreatment, the processing efficiency can be further improved.

It is a schematic diagram of an induced electromotive force. It is a figure which shows the rest potential state of a process substance (carrier | carrier). It is the figure which showed the redox potential (redox potential) of the process substance (carrier | carrier). It is the figure which showed the redox potential (redox potential) of the processing substance (carrier | carrier) similarly. It is the figure which showed the redox potential (redox potential) of the processing substance (carrier | carrier) similarly. It is explanatory drawing which shows the outline | summary of the waste water treatment apparatus for implement | achieving the method of processing the waste_water | drain as to-be-processed water of this invention. It is a figure which shows the structure of a microporous thin film. It is a figure which shows the state which polarization produced by the induced electromotive force from the rest potential of iron oxide. It is a schematic diagram of each reaction. It is a schematic diagram of reaction. It is a figure explaining the structure used for experiment. FIG. 6 is a diagram showing the relationship between the phosphorus removal rate and the magnetic flux density when Fe ₃ O ₄ (magnetite) is used as the carrier S. It is the figure which showed the influence of the chloride ion which gives to the phosphorus removal rate. It is the figure which showed the relationship between a phosphorus removal rate and nitric acid removal rate, and a ferrite constituent metal.

Explanation of symbols

S carrier (treated substance)
1 Wastewater treatment equipment 2 Treatment tank 3 Permanent magnet (magnetic field generating means)
4 Processing chamber 6 Light irradiation device 10 Motor 10A Rotating shaft 12 Drainage sample 24 Microporous thin film (filtration means)
26 Suction pump 28 Blower 30 Film body 32 Spacer 33 Frame body 34 Support body

Claims (14)

  A water treatment method characterized in that a treated substance that generates an induced electromotive force in a magnetic field is introduced into the treated water, and the treated substance moves in the magnetic field to treat the reacted substance in the treated water. .   2. The water treatment according to claim 1, wherein an electromotive force is generated in the treatment substance that is lower than the oxidation-reduction potential of the reaction substance in the treated water, or more noble, or both lower and more noble. Method.   The water treatment method according to claim 1 or 2, wherein the magnetic flux passing through the treatment substance is temporally changed by moving the treatment substance in a static magnetic field or changing the magnetic field itself. .   The water treatment method according to claim 1, 2 or 3, wherein a plurality of types of treatment substances having different rest potentials are introduced into the water to be treated.   The water treatment method according to claim 1, 2, 3, or 4, wherein iron oxide is used as the treatment substance.   The water treatment method according to claim 5, wherein the treatment substance is iron (III) oxide, and the treatment water is irradiated with light.   The water treatment method according to claim 1, 2, 3, 4, 5, or 6, wherein chloride ions are introduced into the water to be treated.   A water treatment apparatus comprising: a treatment substance that is introduced into water to be treated and generates an induced electromotive force in a magnetic field; and an action unit that moves the treatment substance in the magnetic field.   The action means causes the treatment substance to generate an electromotive force that is lower than the oxidation-reduction potential of the reaction substance in the water to be treated, or more noble, or more noble and more noble. 8 water treatment equipment.   The said action means changes the magnetic flux which passes the said processing substance temporally by moving the said processing substance in a static magnetic field, or changing a magnetic field itself, The Claim 8 or Claim characterized by the above-mentioned. 9 water treatment equipment.   The water treatment apparatus according to claim 8, 9 or 10, wherein a plurality of types of the treatment substances having different rest potentials are introduced into the water to be treated. The treatment substance has a fine dimension, and a plurality of the treatment substances are introduced into the water to be treated, and includes a filtering means for filtering the water to be treated.
The said action means is comprised from the magnetic field generation | occurrence | production means which generate | occur | produces a static magnetic field in the said to-be-processed water, and the stirring means to stir the said to-be-processed water, The claim | item 9, the claim | item 9 characterized by the above-mentioned. The water treatment apparatus of Claim 10 or Claim 11.   The water treatment apparatus according to claim 8, 9, 10, 11, or 12, wherein the treatment substance uses iron oxide.   14. The water treatment apparatus according to claim 13, wherein the treatment substance is iron (III) oxide and includes a light generating means for irradiating light into the treated water.

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