JPH06269785A - Treatment of water for decomposing reducing nitrogen with alkali hybromite - Google Patents

Abstract

PURPOSE:To effectively decompose reducing nitrogen neither too much nor too little by adding an alkali hypobromite to the raw water such as river water, lake water, groundwater, industrial waste water and domestic waste water and decomposing the reducing nitrogen contained in the raw water. CONSTITUTION:The raw water 1 contg. reducing nitrogen is introduced into a reducing nitrogen decomposing tank 3. The ozone generated from an ozonizer 5 is sent to a gas-liq. mixing pump 6, an aq. alkali bromide soln. having a specified content of alkali hypobromite is supplied to the pump 6 from an alkali hypobromite forming tank 7 through a control valve 8, and a specified reaction is conducted in the pump 6. Consequently, the liq. mixture concentrated in the alkali hypobromite is returned to the tank 7 from the pump 6. The liq. mixture in the tank 7 is sent to the tank 3 by a transfer pump 9 and agitated by an agitator 4 along with the raw water 1, hence the reducing nitrogen is decomposed, and the treated water 10 is transferred outside the system.

Description

Detailed Description of the Invention

[0001]

[Industrial application] The present invention efficiently treats reducing nitrogen contained in river water, lake water, groundwater, industrial wastewater, domestic wastewater, etc. by using alkali hypobromite. Dissolved water treatment method.

[0002]

[Prior art]

Water is indispensable both in the social life of two people and in their industrial activities. Most of it is tap water, industrial water,
It is supplied as well water. The sources of these waters are rivers, lakes, wells, and rainfall. In recent years, these water sources have become more polluted as social activities and industrial activities become more active, and the pollution not only increases the concentration of pollutants, but also pollutants interact with each other. Then, it has a complicated appearance such as causing new pollution. Contamination of these raw water is cleaned by physical treatment mainly by filtration and chemical treatment using various chemicals. Conventionally, the latter chemical treatment has mainly used chlorine, which has made it possible to obtain stable and clean water for many years.

The method of first injecting chlorine into raw water for the purpose of oxidatively decomposing various substances contained in the raw water is called pre-chlorination, and the treated water is subjected to sedimentation filtration, and then immediately before water supply for sterilization. It is said that post-chlorination is the one to add a small amount of chlorine, but when the pollution degree of raw water is low as before, pre-chlorination is not necessary, and post-chlorination mainly for sterilization is the original chlorination. there were. However, as described above, since the quality of raw water has recently deteriorated, pre-chlorination is required, and the chlorine injection amount is increasing.
In addition, with the increase in the amount, attention has been paid to the fact that an organic chlorine compound harmful to the human body such as trihalomethane is generated by reacting with chlorine in raw water. Of the pollutants in raw water, a large amount of chlorine is required to decompose reducing nitrogen such as ammonia. Theoretically, the amount of nitrogen is 7.6.
That is, about 10 times as much chlorine is actually required, and the amount of the above-mentioned harmful chlorine compounds is increased accordingly.

In order to eliminate the above-mentioned drawbacks of chlorination of raw water, a method has been adopted in which raw water is previously treated with activated carbon or biological treatment. In addition, water treatment by ozone, which has been used for a long time in Europe and America, has been studied in Japan in recent years and has already been used in a wide range of fields. 3 Ozone has a stronger oxidizing power than chlorine and decomposes components that react with chlorine to form harmful substances. Therefore, if the ozone is pretreated, harmful chlorine compounds are reduced even if chlorine is added later. However, ozone has a drawback that it cannot decompose reducing nitrogen by itself. Therefore ozone must be used in combination with chlorine. In that case, first, ozone is used to decompose various harmful substances, and the remaining reducing nitrogen is decomposed with chlorine.

As is clear from the above, ozone is an extremely effective water treatment agent, but it has a drawback that it cannot treat reducing nitrogen. As a method of compensating for this drawback, a method of treating reducing nitrogen by a contact aeration type biological treatment is used, but when the target water temperature becomes 10 ° C or lower, the activity of the organism decreases and the treatment effect deteriorates. There are drawbacks. Further, even in the treatment of reducing nitrogen, nitrogen is oxidized and remains as nitrate nitrogen. In other words, nitrogen has the drawback that it remains in the raw water only by changing the bonding state.
Therefore, in the past, it was impossible to find a definitive method for decomposing reductive nitrogen, so that it was necessary to resort to chlorination.

The conventional water treatment technology has been described above.
This mainly describes the technology for treating water supply. However, the same can be said for the treatment of sewage such as industrial wastewater and domestic wastewater, and the treatment of circulating water in swimming pools. First of all, in the sewerage treatment, raw water with a lot of reducing nitrogen is conventionally treated mainly by activated sludge, but a large amount of treatment has problems in sludge disposal method, etc. There is a drawback that the effect deteriorates. Also, the ammonia treated by this biological treatment is nitrified and remains, so it does not mean that nitrogen is really removed. That is, this treatment still has a drawback that causes the nutrients to be described later. Furthermore, the discontinuity treatment that adds chlorine above the discontinuity point where almost no bound chlorine is detected is a reliable method that is not affected by the water temperature, but a large amount of chlorine is required. It is economically disadvantageous and has a high possibility of producing harmful substances. In the sewerage treatment, when the treatment of reducing nitrogen is uncertain, the river water and lake water from which the treated water is discharged are contaminated, and plankton such as water-bloom are generated to make nutrients nutritive, and the water is deficient in oxygen. A number of problems arise, such as a situation that adversely affects the ecology of aquatic organisms, and that treatment of this water becomes difficult when it is used as tap water. The water in the swimming pool is also polluted by sweat and dirt excreted from the human body, and it contains a lot of reducing nitrogen. This water is recycled after sterilization and purification treatment. If ozone is used for this treatment, reducing nitrogen cannot be treated, and when chlorine is used, the action of bound chlorine causes eye pain. There was a flaw.

The applicants of the present invention have proposed a method for solving the above-mentioned drawbacks of the method for treating raw water of waterworks (Patent application No. 179188 in 1990, Patent application No. 27 in 1992).
5135). In other words, this proposed method makes it possible to decompose the reducing nitrogen by ozone, which has heretofore been impossible due to the catalytic action of alkali bromide added to the raw water. The decomposition reaction is represented by the following formula. O ₃ + Br ⁻ → BrO ⁻ + O ₂ ··· (1) 2NH ₃ + 3BrO ⁻ → N ₂ + 3Br ⁻ + 3H ₂ O ··· (2) That is, ozone reacts with alkali bromide and alkali hypobromite (Reaction (1)), which decomposes reductive nitrogen (ammonia is taken up here as a typical example) into nitrogen and water, and returns to the original alkali bromide (reaction (2)). ).

As is clear from the above reaction formula, once alkali bromide is added to the raw water, this reaction proceeds as long as ozone and ammonia are present. In theory, if ozone is continuously added, reducing nitrogen can be decomposed 100%, and if the supply of ozone is stopped at an appropriate point, the reaction can be stopped at a target amount of decomposition. With this treatment method, several tens of ppm or less of alkali bromide remains in the treated water, 5 but alkali bromide is a harmless substance, and seawater usually contains about 60 ppm. Since the residual amount does not usually exceed the concentration in seawater, there is no problem in health and taste.

The decomposing method of reducing nitrogen described above has the following excellent effects. Since the amount of chlorine used for the treatment of tap water can be extremely reduced, it is possible to prevent the production of large amounts of harmful substances such as trihalomethane and other organic halogen compounds in tap water, and to supply delicious water. can do. At the same time, the amount of chlorine and the amount of activated carbon used for treatment of tap water can be greatly reduced, so that the treatment cost of tap water can be reduced. Since reducing nitrogen contained in domestic wastewater and factory wastewater can be easily removed, treatment costs can be significantly reduced, and at the same time pollution of rivers, lakes and marshes, nutritional nutrition, and accompanying generation of water-bloom. , It is possible to prevent adverse effects on the ecosystem of living things. Further, reducing nitrogen contained in pool water can be easily removed, and the treated water does not cause eye pain.

In the above-mentioned invention, the applicants have further described the outline of a water treatment apparatus in which the proposed method for decomposing reducing nitrogen is actually applied to tap water, waste water, and circulating water in pools. The material which serves as a reference is presented. Further, in order to make a water treatment device of a scale suitable for practical use, it is necessary to mix ozone and water to be treated evenly. For that purpose, ozone must be finely divided into fine particles. Since ozone is easily decomposed,
In some cases, there is a problem that it is not useful for the actual reaction, but it is shown that this can be solved by using a pump such as a friction pump as a reactor.

However, in the proposed method of decomposing reductive nitrogen, a halogen compound such as alkali bromide is used, which is in the form of a compound having an activity such as hypobromite during the reaction. However, there is an unavoidable drawback that it may react with organic matter in raw water to produce harmful organohalogen compounds such as trihalomethane as in the case of chlorine mentioned above.

The applicants have also proposed solutions to these drawbacks (patent application filed on Jan. 22, 1993 (reference number P3740-001N)). The presented invention is made based on the following experimental results. Alkali hypobromite reacts with reducing nitrogen almost selectively when the concentration of reducing nitrogen is high when reducing nitrogen and organic matter coexist in raw water, and the concentration of reducing nitrogen becomes low. For the first time, TOX (total organic halogen compound) is produced by reacting with an organic substance. When the concentration of reducing nitrogen approaches 0, the possibility of TOX formation appears, and if unreacted alkali hypobromite remains,
Its generation increases rapidly, and depending on the conditions, the provisional maximum standard value of TOX in water is 100 μg / l (0.1 ppm).
It will be close to. Therefore, in order to prevent the production of TOX, it is necessary to avoid coexistence of the organic matter and alkali hypobromite in a state where the concentration of reducing nitrogen is low.

The proposed invention detects the content of reducing nitrogen in raw water, calculates the required amount of alkali hypobromite necessary for decomposing the reducing nitrogen, and outputs the control signal. To control the flow rate of the alkali bromide injector installed between the alkali bromide storage tank and the raw water pipe connected to the reducing nitrogen decomposer, or has a built-in amount control function, The amount of ozone generated by the ozone generator connected to the controller is further controlled, the flow rate of the reducing nitrogen decomposer is controlled, and the amount of residual reducing nitrogen in the reaction water after treatment in the reducing nitrogen decomposer or unreacted hyponitrogen Reaction monitoring that detects alkali bromate and calculates and outputs the amount of reducing nitrogen required to react with alkali hypobromite or its unreacted alkali hypobromite, which is required to decompose residual reducing nitrogen Receiving the signal of the vessel, And adjusting the opening of the installed control valve in the bypass pipe connecting the original nitrogen decomposing unit inlet and outlet, and a built-in generation amount controlling function,
(7) Control the ozone generation amount of the adjusting ozone generator connected to the adjusting reducing nitrogen decomposing device, and further control the flow rate of the adjusting reducing nitrogen decomposing device, or the reducing nitrogen storage tank and the adjusting device. The problem described in the above paragraph 0011 is solved by controlling ON-OFF of the reducing nitrogen injector installed between the reducing nitrogen decomposer and the reaction water pipe connected to the reducing nitrogen decomposer.

However, the proposed method still has the following drawbacks. Most ozone generators that have been put into practical use in the past convert oxygen in the air into ozone by spark discharge.
Its generation efficiency is not very good, and since it is easy to decompose and may decompose before it is used in the reaction, especially for raw water with a large content of reducing nitrogen such as wastewater treatment. It has the disadvantages of high power consumption and high processing costs. As described above, there is a drawback that it is difficult to control the ozone injection amount because it is easily decomposed.

[0015]

Means for Solving Problems and Actions Thereof Since the present invention solves the problems described in the paragraph 0014 by making the method of treating raw water containing reducing nitrogen the following constitution. is there. That is, river water, lake water,
Reducing by using alkaline hypobromite characterized by decomposing reducing nitrogen contained in raw water by adding an appropriate amount of alkaline hypobromite to raw water such as groundwater, industrial wastewater, domestic wastewater This is a water treatment method that decomposes nitrogen. This alkali hypobromite can be produced by electrolyzing an alkali bromide solution or by injecting ozone into the alkali bromide solution. Also, this ozone can be produced by electrolysis of water. Further, when the treatment plant is located on the coast, it can be produced by directly electrolyzing seawater.

According to such a constitution, it is desirable to use an alkali hypobromite as an oxidizing agent which decomposes reducing nitrogen. At that time, if the alkali hypobromite is produced and stored elsewhere, there is a drawback that an accurate treatment cannot be obtained because the concentration is lowered due to deterioration of the reagent. For this reason, the production of alkali hypobromite at the point of use is an economically and technically advantageous method.
Hypobromous acid can be produced by electrolysis of alkali bromide, and even if the production is carried out by adding ozone to alkali bromide, the ozone can be produced by electrolysis of water, so that power consumption can be reduced. . Furthermore, if the treatment plant is located on the coast, by directly electrolyzing seawater to produce alkali hypobromite, it is possible to omit the step of alkali bromide production, which results in significant cost savings. it can.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing a first embodiment of a water treatment method for decomposing reducing nitrogen using alkali hypobromite according to the present invention. In the figure, raw water 1 containing reducing nitrogen is sent to a reducing nitrogen decomposition tank 3 through a pipe 2. The reducing nitrogen decomposing tank is equipped with a stirrer 4. Ozone generated from the ozone generator 5 is sent to the gas-liquid mixing pump 6 through the pipe 2. The alkali bromide aqueous solution containing a certain amount of alkali hypobromite is sent from the alkali hypobromite production tank 7 to the gas-liquid mixing pump 6 via the control valve 8. In this pump 00
The following reaction described in the item 07 is carried out, and the mixed solution in which the concentration of alkali hypobromite is increased by this is sent back from the gas-liquid mixing pump 6 to the alkali hypobromite production tank 7. _{^{O 3 + Br - → BrO -}} + O 2 ···· (1)

The mixed solution in the alkali hypobromite production tank 7 is sent to the reducing nitrogen decomposition tank 3 by the transfer pump 9 and mixed with the raw water by the stirrer 4. Therefore, the above-mentioned 0007
The following reactions described in the section are performed. 2NH ₃ + 3BrO ⁻ → N ₂ + 3Br ⁻ + 3H ₂ O (2) 9 As a result, reducing nitrogen is decomposed, and the treated water 10 is transferred from the reducing nitrogen decomposing tank 3 to the outside of the system by the pipe 2. The mixed solution transferred and consumed by the transfer pump 9 is replenished with alkali bromide from a storage tank (not shown) by the pipe 2 to reduce the concentration of alkali hypobromite. The opening degree of the control valve 9 is increased according to the instruction of the acid-alkali concentration meter, and the circulation amount of the mixed solution is increased, whereby the concentration of alkali hypobromite in the mixed solution in the alkali hypobromite production tank is made constant. Retained.

FIG. 2 is a system diagram showing a second embodiment of the present invention, which is a method for electrolyzing alkali bromide to produce alkali hypobromite. In the figure, the solid alkali bromide 1 is fed from the feeder 11a of the alkali bromide tank 11.
2 is sent into the tank, and water 13 is sent into the tank from a nozzle 11c equipped with a valve 11b. The alkali bromide tank 11 is also provided with a stirrer 14, and the alkali bromide aqueous solution generated in the tank by these is supplied to the pipe 1
5 、 Alkali bromide solution storage tank 1 via transfer pump 16
It is transferred to 7 and stored. Further, the aqueous alkali bromide solution is transferred from this storage tank to the alkali hypobromite production tank 19 through the pipe 15 and the transfer pump 18. In this alkali hypobromite production tank, an anode 20 and a cathode 21 are arranged to face each other, and are connected to an external DC power source by a lead wire 22 so that a DC voltage is applied. The alkali hypobromite generated by the action of this electrode is transferred to and stored in the alkali hypobromite storage tank 23 via the pipe 15, and if necessary, the pipe 15 and the transfer pump 24.
A reducing nitrogen decomposition tank 2 similar to that shown in FIG.
Be transferred to. Therefore, the decomposing process of reducing nitrogen is performed as described above. The electrochemical reaction in the alkali hypobromite production tank is as follows. That is, 2Br ⁻ → Br ₂ ＋ 2e ⁻・ ・ ・ ・ (3) at the anode 2H ₂ O ＋ 2e ⁻ → H ₂ ＋ 2OH ⁻・ ・ ・ ・ (4) 10 As the subsequent chemical reaction Br ₂ + 2OH ⁻ → BrO ⁻ ＋ Br ^- ＋ H ₂ O ・ ・ ・ ・ (5)

The above-mentioned alkali hypobromite production tank 19
Is basically an electrolytic cell, and either a diaphragm system in which a diaphragm is provided between both electrodes or a diaphragmless system without a diaphragm may be adopted. However, since the diaphragm method prevents loss due to reduction of hypobromous acid at the cathode, it is possible to obtain a relatively high hypobromous acid production efficiency, but the cell voltage becomes high,
There is also a drawback that the cost becomes high. On the other hand, the non-diaphragm system has a drawback that high production efficiency cannot be obtained unless the flow rate of the electrolytic solution, the electrode shape, the current density, the electrolysis temperature and the like are properly adjusted. Therefore, it is desirable to select which one is to be adopted in consideration of the concentration of hypobromite to be obtained, the electricity charge, the facility cost of the electrolytic cell, and the like. As the diaphragm, a porous membrane having a fine bore made of an inorganic material or an organic material, or an ion-exchange membrane having ion selective permeability can be appropriately used. As the material of the electrode to be used, one having a high catalytic activity of bromine generation is desirable for the anode, and a carbon material such as graphite, an iron oxide sintered material such as ferrite or magnetite, a platinum-plated titanium electrode, a platinum group metal. A titanium electrode coated with an oxide, a lead dioxide-coated titanium electrode, or the like can be used. Further, for the cathode, it can be used as long as it has durability against hydrogen generation in the neutral and alkaline regions, and iron-based materials such as iron, nickel and stainless steel, or carbon materials such as graphite can be used. The points to note regarding the electrolytic cell described above are the ozone generation tank 34 and the seawater electrolytic cell 4 which will be described later.
5 can also be applied based on each known technique.

The third embodiment of the present invention uses a method of electrolyzing water as a method for producing ozone used in the above-mentioned first embodiment. In the first embodiment,
Ozone is used to increase the concentration of alkali hypobromite in an alkali bromide aqueous solution containing a certain amount of alkali hypobromite, and the ozone is supplied from an ozone generator. . Of the reactions of (1) and (2) above, which are the basis for this, the reaction between the reducing 11-nitrogen and the alkali hypobromite shown in (2) is very fast. The reaction between ozone and alkali bromide shown in (3) is rate-determining. Therefore, the problem of the whole reaction is how to increase the concentration of ozone. By the way, in this ozone generator, a method of applying a high frequency voltage to oxygen in the air or pure oxygen to cause electric discharge to change a part of the oxygen into ozone is generally used. In this case, the concentration of ozone gas is usually 0.5 to 2 WT% when air is used as a raw material, and at most 6 to 9 WT% when pure oxygen is used as a raw material. On the other hand, ozone extracted by electrolyzing water has a high concentration, and generally 12 to 18 WT% of ozone can be obtained, and more than 20% can be obtained depending on the conditions.

FIG. 3 is a system diagram illustrating a method for producing ozone by electrolyzing this water. In the figure, first, the water 31 such as tap water is the anion and cation resin 3
It is sent to the deionization tank 32 filled with 3 and the ions of Ca, Mg, Cl, etc. contained in the water are removed. The deionized water is sent to the anode chamber 34a of the ozone generation tank 34. A sensor controls the liquid level in the anode chamber to be constant. The anode 35, cathode 36 are opposed through the membrane, by applying a DC voltage between the electrodes, in the _{anode, 3H 2 O → O 3 +} 6H + + 6e - ···· (6) 2H 2 O → O ₂ ＋ 4H ⁺ ＋ 4e ⁻・ ・ ・ ・ (7) reaction occurs, H ⁺ passes through the membrane and moves to the cathode, and at the same time, water also moves to the cathode. At the cathode, the reaction of 2H ⁺ + 2e ⁻ → H ₂ ··· (8) occurs and hydrogen gas is generated. The electrode 35,
3.5V, 100A obtained by rectifier as an example between 36
When the direct current electricity of 18
At WT% (oxygen concentration 82 WT%), 5.4 g / Hr (equivalent to ozone) of ozone gas was obtained. The hydrogen gas generated from the cathode was about 45 l / Hr, but it was converted to water by reacting with oxygen by a catalyst. 12 The ozone gas thus obtained can react with alkali bromide to generate alkali hypobromite,
If the gas is supplied to the suction port of the gas-liquid mixing pump 6 similar to that shown in FIG. 1, the concentration of alkali hypobromite in alkali bromide containing alkali hypobromite can be increased.

FIG. 4 is a system diagram showing a fourth embodiment of the present invention. In the case of this example, a method of obtaining alkaline hypobromite by directly electrolyzing seawater is used. That is, in the figure, the seawater 41 is directly pumped from the sea to the seawater storage tank 43 by the pump 42, and the transfer pump 44 is also used as needed.
Is sent to the seawater electrolyzer 45. The seawater electrolyzer is provided with an anode 46 and a cathode 47. By applying a DC voltage between these electrodes, alkali hypobromite is generated, and the generated alkali hypobromite is alkali hypobromite. It is sent to the storage tank 48 and stored. Normal, Br in seawater ^-
The concentration is about 60 ppm, and if the concentration of alkali hypobromite that is necessary and sufficient for the decomposition of reducing nitrogen cannot be obtained, add an appropriate amount of alkali bromide to the seawater electrolytic solution for electrolysis. By performing it, a higher concentration of alkali hypobromite can be obtained. The stored alkali hypobromite is sent to the reducing nitrogen decomposing tank 3 similar to that shown in FIG. 1 by the transfer pump 49 as needed, and used for decomposing the reducing nitrogen. The electrochemical reactions in the seawater electrolyzer 45 are as follows. In other words _{^{anode, 2Cl - → CL 2 + 2e}} - The (main reaction) ... (9) some of ^{_{which, Cl 2 + 2Br - → Br}} 2 + 2Cl - ( chemical reaction) ... (10) one Is 2Br ⁻ → Br ₂ + 2e ⁻ (electrochemical reaction) ··· (11) At the cathode, 2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ ··· (12) Further, by the subsequent reaction, 13 Cl ₂ ＋ 2OH ⁻ → ClO ⁻ ＋ Cl ⁻ ＋ H ₂ O ・ ・ ・ ・ (13) Some of them are Br ₂ ＋ 2OH ⁻ → BrO ⁻ ＋ Br ⁻ ＋ H ₂ O ・ ・ ・ ・ (14) ^- all BrO ^- when oxidized, the remaining oxidizing agent is ClO ^- remains as.

[0024]

INDUSTRIAL APPLICABILITY The present invention decomposes reducing nitrogen contained in raw water such as river water using alkali hypobromite,
The necessary alkali hypobromite is produced by electrolyzing alkali bromide, or by adding ozone to alkali bromide, and the ozone is produced by electrolyzing water. By taking a method of directly electrolyzing seawater to produce alkali bromate, the following excellent effects can be obtained. Since an alkali can be used for hypobromous acid immediately after generation, there is no performance deterioration or concentration decrease due to storage, and therefore reducing nitrogen contained in raw water can be effectively decomposed without excess or deficiency. Since ozone having a high concentration is used to produce alkali hypobromite, the production efficiency is high and the treatment cost of reducing nitrogen can be significantly reduced. If the alkali hypobromite is produced by electrolyzing alkali bromide, the production cost is low and the treatment cost of reducing nitrogen can be greatly reduced. When a business site that requires water treatment is located on the coast, alkaline hypobromite can be directly electrolyzed from seawater to produce it, which can further reduce the cost of reducing nitrogen. it can.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of a water treatment method for decomposing reducing nitrogen using alkali hypobromite according to the present invention.

FIG. 2 is a system diagram showing a second embodiment of the present invention.

FIG. 3 is a system diagram showing a third embodiment of the present invention.

FIG. 4 is a system diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

1 Raw water 2 Piping 3 Reducing nitrogen decomposition tank 4
Stirrer 5 Ozone generator 6 Gas-liquid mixing pump 7 Alkali hypobromite production tank 8 Control valve 9 Transfer pump 10 Treated water 11 Alkali bromide tank 11a Feeder 11
b valve 11c nozzle 12 alkali bromide 13 water
14 Stirrer 15 Piping 16 Transfer pump 17 Alkali bromide storage tank 18 Transfer pump 19 Hypochlorous acid bromine production tank 20 Anode 21 Cathode 22 Lead wire 23 Hypochlorous acid storage tank 24 Transfer pump 31 Water 32 Deionization tank 33 Resin 34
Ozone generation tank 34a Anode chamber 35 Anode 36 Cathode 41 Seawater 42 Pump 43 Seawater storage tank 4
4 Transfer pump 45 Seawater electrolysis tank 46 Anode 47 Cathode 48 Alkali hypobromite storage tank 49 Transfer pump

Front page continuation (72) Inventor Kazuhiro Hirao 4-8 Tsurumaki Minami, Hadano, Kanagawa Prefecture 0-101

Claims (5)

[Claims] 1. A method of decomposing reducing nitrogen contained in raw water by adding an appropriate amount of alkali hypobromite to raw water such as river water, lake water, groundwater, industrial wastewater, domestic wastewater. A water treatment method in which reducing nitrogen is decomposed using alkali hypobromite. 2. The alkali hypobromite is produced by electrolyzing an alkali bromide solution, and reducing nitrogen is produced by using the alkali hypobromite according to claim 1. Water treatment method that decomposes. 3. The reducing nitrogen using alkali hypobromite according to claim 1, wherein the alkali hypobromite is produced by injecting ozone into an alkali bromide solution. Water treatment method to decompose. 4. The ozone injected into the alkali bromide is produced by electrolyzing water, and the reducing nitrogen is decomposed using the alkali hypobromite according to claim 3. Water treatment method. 5. The alkali hypobromite according to claim 1, wherein the alkali hypobromite is produced by electrolyzing seawater or seawater to which alkali bromide is added. A water treatment method that decomposes reducing nitrogen.