JP3263520B2 - Control method for catalytic wet oxidizer in treatment of wastewater containing ammonia nitrogen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a wastewater containing ammonia nitrogen, which is subjected to wet oxidation in the presence of a solid catalyst to convert substances contained in the wastewater into nitrogen, carbon dioxide, water and ash. And a method for detoxifying the waste. More specifically, the present invention relates to a method in which various wastewaters containing ammonia nitrogen represented by industrial wastewater and the like are treated in the presence of a solid catalyst and an oxygen-containing gas at a temperature of 100 to 370 ° C. The present invention relates to a method for detoxifying wastewater by subjecting wastewater to wet oxidation treatment under pressure conditions that maintain a phase, thereby converting substances contained in the wastewater to nitrogen, carbon dioxide, water, and ash.

[0002]

2. Description of the Related Art In marine areas, lakes, marshes, rivers, etc., it has been a long time since eutrophication caused red tides and musty odor substances, which are contained in wastewater discharged into the waters. It is caused by nutrients such as nitrogen and phosphorus. For this reason, wastewater regulations on nitrogen and phosphorus are being implemented, and these secondary nutrients cannot be sufficiently treated only by secondary treatment by the conventional activated sludge method. Therefore, it is necessary to newly provide a denitrification step.

Conventionally, methods for removing nitrogen include denitrification by living organisms, stripping by aeration, ion exchange, and oxidative denitrification by oxidizing agents such as hypochlorous acid and ozone. Denitrification treatment by living organisms is a method of nitrifying ammonia nitrogen to nitrate nitrogen and then performing anaerobic treatment of nitrate nitrogen to produce nitrogen gas.However, since the treatment time needs to be long, it is inevitable. There is a problem that the apparatus scale becomes large. The stripping method is a method in which gas is injected into the liquid phase and the dissolved ammonia nitrogen is released into the gas phase. Since this is not a fundamental solution, some process for removing ammonia in the gas phase is required. In the ion exchange method, it is necessary to frequently regenerate the ion-exchange base material and waste water, so that the ion-exchange base material contains a large amount of ions other than nitrogen-containing ions. In addition, the denitrification method using hypochlorous acid has a risk of generating organic chlorine, which has recently become a problem. The denitrification method using ozone also requires the presence of bromine ions as a catalyst, and both require a large amount of oxidizing agent. As a result, the cost increases.

On the other hand, as a method of treating wastewater containing a high concentration of ammonium nitrate, a method of treating the wastewater by catalytic wet oxidation has been proposed (JP-A-61-222585, JP-A-61-222586, 61-2
No. 22587, JP-A-61-222588,
JP-A-61-222589, JP-A-61-245
883, JP-A-61-245883, JP-A-61-257290, JP-A-61-25729
No. 1, Japanese Patent Application Laid-Open No. 61-257292,
-59094, JP-A-4-61987, JP-A-4-200692, JP-A-4-200790
No.). These are 100 to 3 in the presence of a specific catalyst.
This is a method of performing wet oxidation treatment at a temperature of 70 ° C. and a pressure condition in which waste water retains a liquid phase.

[0005]

However, when the present inventors treat ammonia-nitrogen-containing wastewater, the treatment efficiency may fluctuate greatly due to fluctuations in the concentration of wastewater and shake of the apparatus itself. Admitted. That is, when treating ammonia-nitrogen-containing wastewater by the catalytic wet oxidation method,
It became clear that stable high treatment efficiency could not be obtained unless the equipment conditions were always kept optimally for the concentration of wastewater.

However, in an actual apparatus, the concentration of waste water is not constant, but always fluctuates. Therefore, in practice, it is impossible to perform a stable and sufficient nitrogen treatment unless the apparatus conditions are always controlled to an optimum state in the treatment of the wastewater containing ammonia nitrogen.

[0007]

On the other hand, the inventors of the present invention have conducted intensive studies, and as a result, when treating wastewater containing ammonia nitrogen by the catalytic wet oxidation method, supply the nitrogen into the apparatus with respect to the treatment efficiency of nitrogen. The effect of oxygen content was found to be very large. That is, the concentration of ammonium ion and nitrate ion present in the treated water varies depending on the type of the catalyst used, but no matter what kind of catalyst is used when the wastewater containing ammonia nitrogen is treated by the catalytic wet oxidation method. As shown in the conceptual diagram of FIG. 1, when the supplied oxygen amount is small, the ammonia nitrogen remains in the treated water without being oxidized, and when the supplied oxygen amount becomes excessive, It has been found that nitrogen is converted to nitrate nitrogen and is present in the treated water at a high concentration, so that sufficient treatment cannot be performed as the total nitrogen concentration in the treated water.

Further, it has been found that, when the ammonia-nitrogen-containing waste water is subjected to catalytic wet oxidation treatment, the concentration of ammonium ions in the treated water discharged from the catalytic wet oxidation apparatus serves as an index for judging the amount of supplied oxygen. By controlling the amount of oxygen-containing gas flowing into the apparatus so as to control the concentration to within a certain range or to a concentration value, it is possible to easily and stably minimize the influence of fluctuations in the concentration of wastewater and perform stable treatment. I found that it was possible. In addition, when the ammonia-nitrogen-containing wastewater is subjected to catalytic wet oxidation treatment,
We found that the oxygen concentration in the gas together with the ammonium ion concentration in the treated water discharged from the catalytic wet oxidizer was an index to determine the amount of supplied oxygen, and based on these measured values, the amount of oxygen-containing gas flowing into the reactor It has been found that by controlling the concentration of water, it is possible to easily and stably minimize the influence of fluctuations in the concentration of wastewater and to perform a stable treatment. The present invention has been completed based on these findings.

The present invention provides a simple and optimal control method for performing a stable treatment by minimizing the effects of fluctuations in the flow rate and concentration of the wastewater in the catalytic wet oxidation treatment of wastewater containing ammonia nitrogen. To provide.

In the present invention, when the ammonia-nitrogen-containing wastewater is subjected to catalytic wet oxidation treatment, the optimum range of the ammonium ion concentration value in the treated water is set in advance to CL to CH,
After gas-liquid separation of the gas-liquid mixed fluid discharged from the catalytic wet oxidation device, the oxygen concentration in the gas phase and the ammonium ion concentration in the treated water are measured, and the measured oxygen concentration falls within a preset range or the concentration. And controlling the amount of oxygen-containing gas flowing into the apparatus so that the concentration and the ammonium ion concentration value fall within the range of CL to CH or a set concentration value. .

In the catalytic wet oxidizer, fluctuations in the concentration of waste water affect the temperature of each part of the reactor, the properties of the treated water, the oxygen concentration of the exhaust gas, and the like. The temperature of each part of the reactor changes remarkably when the concentration of the wastewater is extremely different before and after the fluctuation, but the change is usually small, and it is difficult to detect and use the temperature difference for control. is there. On the other hand, the concentration of ammonium ions in the treated water and the concentration of oxygen in the exhaust gas are indicators that clearly indicate the oxidation state in the apparatus.

In the present invention, as shown in FIG. 2, an optimum range of the ammonium ion concentration in the treated water is set in advance, and the supplied oxygen amount is increased or decreased so as to fall within the set range. The control is performed by increasing the supplied oxygen amount as the ammonium ion concentration in the treated water increases, and decreasing the supplied oxygen amount as the ammonium ion concentration in the treated water decreases. That is, the optimum range of the ammonium ion concentration in the treated water is set to CL to CH, and
By controlling the supplied oxygen amount so as to fall within the range of L to CH, stable processing is performed. Further, an optimum concentration value of the ammonium ion concentration in the treated water may be set in advance, and the supplied oxygen amount may be increased or decreased so as to approach the set concentration value. The control is performed by increasing the supplied oxygen amount as the ammonium ion concentration in the treated water increases, and decreasing the supplied oxygen amount as the ammonium ion concentration in the treated water decreases. That is, for the concentration of ammonium ions in the treated water, the optimum concentration value C is set, and the amount of supplied oxygen is controlled so that the concentration of ammonium ions in the treated water approaches C, whereby stable treatment is performed.

As a method of controlling the supplied oxygen amount, the supplied oxygen amount is changed when the amount deviates from a set range, and the supplied oxygen amount is changed according to the deviated amount when the amount deviates from the set range. A general method such as changing the supplied oxygen amount according to a deviation from the set target value is used.
Also, when changing the supplied oxygen amount according to the deviation,
The amount of change can be determined by a commonly used method such as stepwise, proportional, or quadratic curve.

By determining the optimum range or concentration value of the ammonium ion concentration in the treated water, it is possible to detect an increase and a decrease in the supplied oxygen amount with respect to the required oxygen amount. Processing can be performed. One end of the optimum range of the ammonium ion concentration in the treatment water is not determined, and the maximum value of the ammonium ion concentration in the treatment water is determined and the supplied oxygen amount is controlled so as not to exceed the value. Proper processing cannot be performed by setting the minimum value and controlling the supplied oxygen amount so as not to fall below the minimum value.
That is, to determine the maximum value of the ammonium ion concentration in the treated water and control the supplied oxygen amount so as not to exceed the maximum value, it is possible to detect the phenomenon of insufficient supplied oxygen, but it is impossible to detect the excessive phenomenon. In some cases, the supplied oxygen amount becomes excessively large and nitrate ions may be present in the treated water. In addition, by determining the minimum value of the ammonium ion concentration in the treated water and controlling the supplied oxygen amount so as not to fall below that value, it is possible to detect the excess phenomenon of the supplied oxygen amount, but it is not possible to detect the insufficient phenomenon. In some cases, the amount of supplied oxygen is insufficient and ammonium ions may be present in the treated water.

The optimum range or concentration value of ammonium in the treated water varies greatly depending on the concentration of ammonia nitrogen in the waste water, required treatment efficiency, the type of catalyst used, and the sensitivity and accuracy of the ammonium ion concentration meter. Usually, it is set under the condition of not less than the detection limit of the ammonium ion concentration meter and not more than the required treatment water quality. If the concentration below the detection limit of the ammonium ion concentration meter is set to the optimum range or concentration value, the excess phenomenon of the supplied oxygen amount cannot be detected, and the treatment efficiency may decrease due to the presence of nitrate ions in the treated water. is there. Further, when the concentration equal to or higher than the required treatment water quality is set to the optimum range or concentration value, the supply oxygen amount is controlled so as to increase the treatment efficiency even when the required treatment efficiency is not obtained. Absent.

The optimum range or concentration value of the ammonium ion concentration in the treated water is higher as the total nitrogen treatment efficiency is higher, but is set to be equal to or higher than the detection limit of the ammonium ion concentration meter for the above-mentioned reason. In addition, it is preferable that the width of the control range is smaller, because the control is always performed appropriately. The target value of the ammonium ion concentration may be set without the width of the control range, and the supply amount of oxygen may be constantly controlled. One example is iron-prepared in a catalyst preparation example described below.
When a zirconium-palladium catalyst is used and the ammonia nitrogen concentration in the wastewater is 1,500 mg / l and the required ammonium ion concentration in the treated water is 10 mg / l or less, the control range of the ammonium ion concentration in the treated water is as follows. The setting is 1 to 10 mg / l, preferably 3 to 8 mg / l
1 or the target value is set to 5 mg / l to control the supplied oxygen amount.

Further, in the present invention, it is preferable that the oxygen concentration in the exhaust gas is detected together with the ammonium ion concentration in the treated water, and the supplied oxygen amount is controlled based on the detected ammonium ion concentration and oxygen concentration. By measuring the oxygen concentration of the exhaust gas and reflecting it in the control of the supplied oxygen amount,
The time lag of the concentration fluctuation of the water to be treated can be made shorter than that in the case of the control using the ammonium ion concentration alone in the treatment water, and the treatment corresponding to the rapid concentration fluctuation can be performed. In addition, by detecting the oxygen concentration in the exhaust gas together with the ammonium ion concentration in the treated water, and controlling the amount of supplied oxygen by the detected ammonium ion concentration and oxygen concentration, the treated water is more controlled than the oxygen concentration alone in the exhaust gas. The properties can be accurately grasped, and more stable processing can be performed. In addition to these, detecting the oxygen concentration in the exhaust gas together with the ammonium ion concentration in the treated water, and controlling the supplied oxygen amount based on the detected ammonium ion concentration and oxygen concentration,
Measuring the concentration of ammonium ions in the treated water to accurately detect when the amount of supplied oxygen is too low, and measuring the concentration of oxygen in the exhaust gas to quickly and accurately detect when the amount of supplied oxygen is excessive. Since it can be performed, more efficient and stable processing can be performed.

In the case where the amount of supplied oxygen is controlled by using both the ammonium ion concentration in the treated water and the oxygen concentration of the exhaust gas, the maximum value of the ammonium ion concentration in the treated water is required in advance. The supply oxygen amount may be controlled so as to be equal to or lower than the water quality so that the ammonium ion concentration in the treated water does not exceed the set value. That is, when the supply oxygen amount is excessive, the detection can be performed by the oxygen concentration in the exhaust gas, so that it is not necessary to set the minimum value of the optimum range of the ammonium ion concentration.
As a control method, it is preferable to increase the amount of supplied oxygen as the concentration of ammonium ions increases.

When the supplied oxygen amount is controlled by using both the ammonium ion concentration in the treated water and the oxygen concentration of the exhaust gas, the maximum value of the oxygen concentration in the exhaust gas is determined in advance with respect to the oxygen concentration in the exhaust gas. And the supply oxygen gas amount may be increased or decreased so as to fall below the set value. By determining the maximum value of the oxygen concentration in the exhaust gas, an excess phenomenon of the supplied oxygen amount is detected, and it is prevented that the supplied oxygen amount becomes excessive and the nitrate ion concentration in the treated water increases. The control is performed by decreasing the supplied oxygen amount as the oxygen concentration in the exhaust gas increases. The maximum value of the oxygen concentration to be set greatly varies depending on the required treated water quality, the catalyst to be used, and the oxygen concentration in the oxygen-containing gas to be used. A zirconium-palladium catalyst is used, air is used as the oxygen-containing gas, and the ammonia nitrogen concentration in the wastewater is 1,50.
0mg / l, required total nitrogen concentration in treated water is 20m
In the case of g / l or less, it is 1 vol%.

The oxygen-containing gas in the present invention is a gas containing oxygen, and specific examples thereof include air, oxygen-enriched air, and exhaust gas containing oxygen. The oxygen concentration in the oxygen-containing gas is 3 vo
l% or more, preferably 5 vol% or more. When the oxygen concentration in the oxygen-containing gas is 3 vol% or less, the oxygen concentration in the exhaust gas after treatment becomes too low, and the reliability of the measurement value obtained by the oximeter becomes low. In some cases, the amount of oxygen supplied decreases, and the control of the supplied oxygen amount cannot be performed accurately, so that stable processing cannot be performed. In addition, since the above oxygen concentrations are all on a dry basis and are concentration values in a state where water vapor is separated, when performing measurement without separating water vapor, it is necessary to correct an error due to water vapor to determine a control value. I just need.

In the present invention, the oxygen-containing gas is continuously introduced into the apparatus and used for treating wastewater. When introduced intermittently, anoxic portions appear in the wastewater, and the treatment is not performed. As a result, there is a possibility that the treatment efficiency is lowered, which is not preferable.

In the present invention, the term "ammonia nitrogen" is a general term for ammonia and ammonium ions dissolved in a liquid phase. For example, dissolved salts such as ammonium sulfate and ammonium chloride, aqueous ammonia, etc. But are not limited to these.

In the present invention, the concentration of ammonia nitrogen in the wastewater to be treated is not limited as long as it is dissolved in an aqueous solution.

As the catalyst used in the present invention, any catalyst may be used as long as it is a solid catalyst having durability and activity under wet oxidation reaction conditions. For example, titanium, silicon, At least one element selected from the group consisting of zirconium, manganese, iron, cobalt, nickel, tungsten, cerium, copper, silver, gold, platinum, palladium, rhodium, ruthenium, and iridium, is insoluble or hardly soluble in water. It is a solid catalyst containing a compound. Further, the catalyst A component is selected from the group consisting of manganese, iron, and at least one element insoluble or hardly soluble in water, and the catalyst B component is selected from the group consisting of titanium, silicon, and zirconium. Water-insoluble or hardly soluble compound of at least one element, and cerium, tungsten, copper, silver, gold, platinum, palladium,
It is preferable to use a solid catalyst containing a water-insoluble or hardly soluble compound of at least one element selected from the group consisting of rhodium, ruthenium, and iridium. The ratio of each catalyst component in the catalyst is such that component A is 20 to 98.9% by weight in the form of an oxide, component B is 1 to 80% by weight in the form of an oxide, and component C is 0 to 8% by weight in the form of a metal or a compound. A suitable range is from 0.1 to 20% by weight. Preferably, component A ranges from 40 to 95% by weight in oxide form, component B ranges from 5 to 60% by weight in oxide form, and component C ranges from 0.1 to 15% by weight in metal or compound form. is there. When the component A is out of the above range, the catalytic activity is insufficient. When the component C is also below the above range, the catalytic activity becomes insufficient. In the case of a noble metal such as platinum, palladium and rhodium, the catalytic activity becomes insufficient. If the ratio exceeds, the raw material cost increases, and a correspondingly sufficient effect cannot be expected.

The catalyst used in the present invention preferably has the composition specified as described above.
Various things such as a granular form, a pellet form, and an integrated structure such as a honeycomb can be adopted.

If the wastewater containing ammonia nitrogen is treated using the above catalyst, the total nitrogen treatment efficiency will be greatly increased.

In the present invention, the temperature during wastewater treatment is 100.
370 ° C, preferably 150 ° C to 300 ° C. If the temperature at the time of wastewater treatment is 100 ° C. or less, it is not possible to sufficiently remove ammonia nitrogen.
In the above case, the temperature exceeds the critical temperature of water, and the reactor becomes expensive, which is not preferable. Pressure at processing temperature,
Set the pressure at which the wastewater holds the liquid phase. In the wet oxidation reaction, the higher the oxygen partial pressure, the faster the reaction proceeds.The higher the pressure during the process, the faster the reaction. However, the higher the pressure of the device, the more expensive the device itself. , May be set appropriately according to the processing efficiency.

In the present invention, the inflow velocity of the waste water is preferably in the range of 0.5 to 20 / hr in space velocity (LHSV) with respect to the catalyst. If the LHSV is 0.5 / hr or less, the treatment efficiency does not increase with respect to the amount of the catalyst, and the cost becomes high. If the LHSV is 20 / hr or more, the processing efficiency of ammonia nitrogen is insufficient, which is not preferable.

In the present invention, the supply amount of the oxygen-containing gas is
There is no particular limitation because it is automatically controlled during the processing.

As the ammonium ion concentration meter used in the present invention, any one can be used as long as it has a function of continuously measuring the concentration of ammonium ion in the liquid phase and outputting a detected value. As the detector, various known detectors such as conductivity detection by ion chromatography, FTD by gas chromatography, and ion electrodes can be applied.

As the oxygen concentration meter used in the present invention, any device can be used as long as it has a function of continuously measuring oxygen in the gas phase and outputting a detected value.
For example, commercially available ones such as a zirconia oxygen analyzer, a galvanic cell oxygen analyzer, and a magnetic oxygen analyzer are used.

[0032]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

(Catalyst Preparation Example) Ferric nitrate is dissolved in water, zirconyl nitrate and palladium nitrate are added, and an aqueous solution of sodium hydroxide is added to adjust the pH to 9, which is filtered and washed to obtain a cake. It is dried, calcined at 700 ° C., and pulverized to obtain an iron-zirconium-palladium oxide powder (weight ratio Fe 2 O 3: ZrO 2: Pd = 60: 39.5: 0.
5) was obtained.

The thus obtained oxide powder is added with starch,
After adding water and mixing well, the mixture was shaped into a pellet (cylindrical, average diameter 5 mm, length 6 mm), dried, and calcined at 400 ° C. for 4 hours to obtain a completed catalyst.

(Comparative Example 1) In accordance with the flow shown in FIG. 3, waste water having the composition shown in Table 1 was treated. First, drain water sent from tank 5 is pumped
The pressure was increased to 70 kg / cm ² G at a flow rate of 1 liter / hr and supplied into the apparatus. A 10% by weight aqueous sodium carbonate solution was pressurized and supplied by the pump 4 at a flow rate of 100 ml / hr through the line 12, and was mixed with the wastewater. On the other hand, after the air supplied from the line 13 was pressurized by the compressor 7, it was mixed into the mixed liquid. This gas-liquid mixture was heated to 250 ° C. in the heat exchanger 2 and the heater 16 via the line 14 and then introduced into the wet oxidation tower 1. The wet oxidation tower 1 is filled with 0.5 liter of the catalyst obtained in the catalyst preparation example, the wastewater is treated in the wet oxidation tower 1, and the treated water is passed through a line 15 to a heat exchanger 2.
, And flowed to the gas-liquid separator 6. Gas-liquid separator 6
In, the liquid level is detected by a liquid level controller (LC), the liquid level control valve 8 is operated to maintain a constant liquid level, and the pressure is detected by a pressure controller (PC) to operate the pressure control valve 9. It is operated to maintain a constant pressure when activated. The oxygen concentration in the gas discharged from the pressure control valve 9 is measured by an oxygen concentration meter 10, and the ammonium ion concentration of the treated water is measured by an ammonium ion detector 1.
1 is constantly monitored.

When the value of the ammonium ion concentration meter 11 is 5
The supply gas amount was automatically controlled so as to be in mg / l, and the wastewater concentration was changed within the range of Table 1 every 24 hours to perform a continuous treatment test for 100 hours.

FIG. 4 shows the time-dependent changes in the concentration of ammonia in the wastewater and the concentrations of ammonia and nitric acid in the treated water. Incidentally, nitrite ions were not detected in the treated water.

(Comparative Example 2) A treatment test was performed under the same conditions as in Comparative Example 1 except that the amount of supplied air was kept constant without following the ammonium ion concentration in the treated water. FIG. 5 shows the results. Incidentally, nitrite ions were not detected in the treated water.

[0039] (Example 1) the ammonium ion concentration is 1 mg / l or less, the process in the same conditions as in Comparative Example 1 except for automatically controlling the supply amount of gas so that the oxygen concentration in the exhaust gas of 1% or less Test Was done. FIG. 7 shows the results. Incidentally, nitrite ions were not detected in the treated water.

(Comparative Example 3) A processing test was performed under the same conditions as in Comparative Example 1 except that the supply gas amount was automatically controlled so that the ammonium ion concentration was 1 mg / l or less. FIG. 7 shows the results. Incidentally, nitrite ions were not detected in the treated water.

[0041]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the relationship between the amount of oxygen supplied and the concentrations of ammonium ions and nitrate ions in treated water when treating wastewater containing ammonia nitrogen by a catalytic wet oxidation reaction method.

FIG. 2 is a conceptual diagram when the amount of supplied oxygen is controlled by the concentration of ammonium ions in treated water. CH: Maximum value of the optimal range of the ammonia ion concentration in the treated water CL: Minimum value of the optimal range of the ammonia ion concentration in the treated water C: Target value of the ammonia ion concentration in the treated water QH: Supply oxygen amount when CL is QL: Supply oxygen amount when ammonia ion concentration in treated water is CH Q: Supply oxygen amount when ammonia ion concentration in treated water is C

FIG. 1. Catalytic wet oxidation reactor Heat exchanger 3. Drainage field pump ４． 4. Aqueous sodium carbonate solution field pump Drain tank 6. 6. Gas-liquid separator 7. Air compressor Liquid level control valve 9. Pressure control valve 10. Oxygen meter 11. pH meter 12. 12. Sodium carbonate aqueous solution field line Air line 16. Electric heater

FIG. 4 shows the results of Comparative Example 1 , in which the ammonium ion concentration in the wastewater was changed stepwise every 24 hours to show the changes in the ammonium ion concentration and the nitrate ion concentration in the treated water. It is.

FIG. 5 shows the results of Comparative Example 2 , in which the ammonium ion concentration in the wastewater was changed stepwise every 24 hours to show the changes in the ammonium ion concentration and the nitrate ion concentration in the treated water. It is.

FIG. 6 shows the results of Example 1 in which the ammonium ion concentration in the wastewater was changed stepwise every 24 hours to show the changing state of the ammonium ion concentration and the nitrate ion concentration in the treated water. It is.

FIG. 7 shows the results of Comparative Example 3 , in which the ammonium ion concentration in the wastewater was changed stepwise every 24 hours to show the changes in the ammonium ion concentration and the nitrate ion concentration in the treated water. It is.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kiichiro Mitsui 992, Nishioki, Okihama-shi, Abashiri-ku, Himeji-shi, Hyogo Japan Nippon Shokubai Co., Ltd. Examiner, Catalyst Research Laboratory Tadahiro Sanada (56) References A) JP-A-2-265696 (JP, A) JP-A-3-181390 (JP, A) JP-A-59-55390 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) C02F 1/72 C02F 1/58 B01J 3/00 B01J 19/00

Claims (1)

(57) [Claims] When the ammonia-nitrogen-containing waste water is subjected to catalytic wet oxidation treatment, the optimum range of the ammonium ion concentration value in the treated water is set in advance to CL to CH, and the gas-liquid mixed fluid discharged from the catalytic wet oxidation device is used. After the gas-liquid separation, the oxygen concentration in the gas phase and the ammonium ion concentration in the treated water are measured, and the measured oxygen concentration is within a preset range or a preset concentration value, and the ammonium ion concentration value is CL to CH. Controlling the amount of oxygen-containing gas flowing into the apparatus so that the concentration value falls within the range of or within a set value.