JPH0459094A - Treatment of waste water containing ammonium nitrate - Google Patents

Abstract

PURPOSE:To efficiently decompose not only NH4<+> but also NO3<-> by performing wet-type thermal decomposition for waste water in the absence of oxygen and performing wet-type oxidative decomposition therefor. CONSTITUTION:High-temp. water to be treated which has been subjected to wet-type oxidative decomposition is sent to a heat exchanger 9 via a line 27. After pretreatment of waste raw water is performed herein, it is sent to a cooler 31 via a line 29 and cooled. A water supply line 33 and a drainage line 35 are connected to the cooler 31. Supply of cooling water and discharge of drainage are always performed. The treated water discharged from the cooler 31 is sent to a gas-liquid separator 39 via a line 37 and separated into a liquid phase discharged from a line 41 and a gas phase discharged from a line 43. Further in order to control the pressure in the system during reaction treatment, a pressure detection device 57 is provided to the gas-liquid separator 39. Thereby the degree of opening of a valve 49 is controlled in accordance with the pressure of the inside of the gas-liquid separator 39.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for treating wastewater containing ammonium nitrate.

Prior art and its problems In recent years, chemical oxygen demand substances (COD) have been increasing from the viewpoint of water quality regulation.
components) as well as nitrogen components (especially ammonia nitrogen)
Removal of this has also become an important issue.

As a result of long-term research on various methods for treating ammonia-containing wastewater, the present inventors have discovered that wet oxidation treatment can be carried out in the presence of a specific catalyst and under specific conditions, making it easy to operate and practical and economical. Completed a method for treating ammonia-containing wastewater with
No., Special Publication No. 5642992, Special Publication No. 57-42391
No., Special Publication No. 58-27999, Special Publication No. 57-3332
0 etc.).

Recently, as the proportion of nuclear power generation in the power generation industry has increased, the treatment of NH4N03-containing wastewater discharged from the processing of uranium raw materials and the reprocessing process of spent uranium fuel is becoming an important technical issue. The present inventor attempted to apply the above-mentioned series of ammonia-containing wastewater treatment technologies (hereinafter referred to as "prior application technology - (2)") to the treatment of such NH4NO3-containing wastewater. In this attempt, it was found that although NI(+) ions were decomposed with extremely high efficiency, the decomposition of NO3- ions was not always satisfactory.

This means that the NH4No3 concentration in the wastewater is 1% (100
This is presumed to be due to the fact that it can reach from 10% (100,000 ppm) to about 10% (100,000 ppm).

As a result of further research, the present inventors found that by implementing the prior art technology, by reducing the amount of oxygen added, not only NH4+ ions but also NO3- ions in wastewater containing high concentration NH4NO3 were increased. It was successfully decomposed efficiently (see Japanese Patent Application Laid-Open No. 61-222585; hereinafter, the technology disclosed therein will be referred to as the prior invention - (2)).

However, in the treatment of wastewater containing high concentration NH4NO3, particularly from a practical standpoint, it is desired not only to improve the treatment efficiency but also to lower the cost (reduction in equipment costs, operating costs, etc.).

Means for Solving the Problems In view of the above-mentioned current situation, the inventor of the present invention has further conducted various studies, and as a result, the ammonia component in the NH4NCh-containing wastewater,
Instead of the method of the previous application-■, in which the wet pyrolysis of the NH4NO3-containing wastewater is carried out in the presence of oxygen that is less than the theoretical amount of oxygen necessary to decompose organic and inorganic substances, the wastewater is subjected to wet pyrolysis in the absence of oxygen. We have discovered the completely unexpected fact that when carrying out wet thermal decomposition and then wet oxidative decomposition, not only NH and + ions but also No3 ions can be efficiently decomposed.

Furthermore, according to the inventor's subsequent research, wastewater +1.1
When adding ammonia so that <NH3-N/N03-N≦2 (-E-R ratio) and performing wet thermal decomposition of wastewater in the absence of oxygen, and then performing wet oxidative decomposition, It has been found that the decomposition efficiency of NH, + ions and NO3 - ions is further improved.

Furthermore, according to the inventor's subsequent research, when NH4NO3-containing wastewater to which an acid and at least one acid-generating substance has been added is subjected to wet thermal decomposition in the same manner as described above, and subsequently wet oxidative decomposition is performed, the decomposition efficiency is was found to be further improved.

Furthermore, 0.1 <NH3-N/NCh-N≦2
When NH4NO3-containing wastewater is subjected to wet oxidative decomposition to which ammonia and at least one of an acid and an acid-generating substance are added such that the molar ratio becomes I found out that it can be done.

That is, the present invention provides the following four types of wastewater treatment methods.

(ii) Ammonium nitrate-containing wastewater is heated to a pH of about 1 to 11.5 in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, their insoluble or sparingly soluble compounds, and base metals, and in the absence of oxygen. Temperature 100-3
After wet pyrolysis at 70°C, the treatment solution is treated in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, their insoluble or poorly soluble compounds, and base metals, and in the presence of ammonia and organic compounds in the treatment solution. in the presence of a gas containing 1 to 1.5 times the theoretical amount of oxygen required to decompose organic and inorganic substances, at a pH of about 1 to 11.5 and a temperature of 1.
A method for treating wastewater containing ammonium nitrate, comprising wet oxidation at 00 to 370°C.

■ Ammonium nitrate-containing wastewater to which ammonia has been added so that the molar ratio is 0.1 < N H3N/N O3N≦2 is activated with at least one selected from the group consisting of noble metals, their insoluble or sparingly soluble compounds, and base metals. pH in the presence of a supported catalyst as a component and in the absence of oxygen.
After wet pyrolysis at a temperature of about 1 to 11.5 and a temperature of 100 to 3700 C, the treatment liquid is treated with a supported catalyst containing at least one selected from the group consisting of noble metals, insoluble or poorly soluble compounds thereof, and base metals as an active component. pH approximately 1 to 11.5 in the presence of a gas containing oxygen in an amount of 1 to 1.5 times the theoretical amount of oxygen required to decompose ammonia, organic substances, and inorganic substances in the treatment liquid. A method for treating wastewater containing ammonium nitrate, comprising wet oxidation at a temperature of 100 to 370°C.

■ Ammonium nitrate-containing wastewater to which an acid and at least one acid-generating substance has been added is treated in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, their insoluble or sparingly soluble compounds, and base metals, and After wet pyrolysis at a pH of about 1 to 11.5 and a temperature of 100 to 370°C, the treatment solution is treated with at least one active ingredient selected from the group consisting of noble metals and their insoluble or sparingly soluble compounds, and base metals. pH of approximately 1 in the presence of a supported catalyst and a gas containing 1 to 1.5 times the theoretical amount of oxygen required to decompose ammonia, organic substances, and inorganic substances in the treatment liquid. ~11.5, temperature 100~3
A method for treating wastewater containing ammonium nitrate, characterized by wet oxidation at 70°C.

■ Ammonium nitrate-containing wastewater to which ammonia and at least one acid and acid-generating substance have been added so that the molar ratio is 0.1 <NH3-N/NO3-N≦2 is mixed with precious metals and their insoluble or sparingly soluble compounds. and a supported catalyst containing at least one selected from the group consisting of base metals as an active ingredient and in the absence of oxygen to a pH of about 1 to 11.
．． 5. After wet pyrolysis at a temperature of 100 to 370°C, the treatment liquid is treated in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, insoluble or poorly soluble compounds thereof, and base metals. In the presence of a gas containing oxygen in an amount of 1 to 1.5 times the theoretical amount of oxygen necessary to decompose ammonia, organic substances, and inorganic substances, pH is approximately 1 to 11.5, and temperature is 100 to 370. A method for treating wastewater containing ammonium nitrate, characterized by wet oxidation at ℃.

In the following, the methods described in ``-2■, ■, ■, and 0 are respectively referred to as the ``first method of the present application'' and 1 the second method of the present application''.
, "the third method of the present application" and "the fourth method of the present application", and when these are collectively referred to as the present invention or the present invention method.

The present invention targets all wastewater containing NH and 1NO3, and is particularly suitable for treating high-concentration wastewater with NH and NO3 concentrations of 1% or more. Note that the wastewater may contain both organic substances and inorganic substances.

In addition, in both the wet pyrolysis step and the wet oxidation step of the present invention, the pH of the wastewater is about 1 to 11.5, more preferably 3 to 11.5.
9 is efficient (implemented).

Hereinafter, the "first method of the present application," the "second method of the present application," the "third method of the present application," and the "fourth method of the present application" will be explained in detail, respectively.

■2 The third method of the present application A) Wet pyrolysis process The catalytic active components used in the wet pyrolysis of the first method of the present application include ruthenium, rhodium, palladium, osmium, iridium, platinum, and gold as precious metals. Compounds that are insoluble or poorly soluble in water such as
Base metals include iron, cobal l-, manganese, tungsten, copper, nickel and magnesium;
One or more of these can be used.

Examples of insoluble or poorly soluble noble metal compounds include ruthenium dichloride, platinum dichloride, ruthenium sulfide, and rhodium sulfide. In addition, if necessary, co-catalyst components such as tellurium, selenium, and lanthanum can be used in conjunction with these catalytic active components to increase the activity of the processing active components and improve the heat resistance, durability, and mechanical strength of the catalyst. Direction-1- etc. can be aimed at. These catalytically active components and co-catalyst components can be prepared using conventional methods such as titania, zirconia, alumina, silica, aluminium oxide, activated carbon, or nickel, nickel-chromium, nickel-chromium-aluminum, nickel-chromium-iron, etc. It is used by being supported on a carrier such as a porous metal body. The amount of catalyst active component supported is usually 0 of the carrier weight.
．． 05-25%, preferably 0.5-3%. In addition, the co-catalyst component is 0.01 to 30% relative to the catalytically active component.
It is used within a range of about %. The catalyst is used in a state where it is supported in various forms such as spheres, pellets, cylinders, crushed pieces, powders, and honeycombs. The reaction column volume is
In the case of a fixed bed, the space velocity of the liquid is 0.5 to 101/h.
r (empty column basis), more preferably 1 to 5'/hr (empty column basis). The size of the catalyst used in the fixed bed is usually about 3 to 50 mm, preferably about 5 to 25 mm. In the case of a fluidized bed, the amount of catalyst that can form a fluidized bed in the reaction column, usually 0.5 to 20% by weight.
, more preferably 0.5 to 10% by weight, is used by suspending it in the form of a slurry in waste water. In the second operation of "Practical use in a fluidized bed," the catalyst is supplied to the reaction tower in the form of a slurry suspended in wastewater, and after the reaction is completed, the catalyst is separated from the treated wastewater discharged through sedimentation, centrifugation, etc. Separate and recover using an appropriate method and use again. Therefore, considering the ease of catalyst separation from treated wastewater, the particle size of the catalyst used in the fluidized bed is approximately 0.
．． More preferably, the thickness is about 15 to about 0.5 mm.

The temperature during the thermal decomposition reaction is usually 100 to 370°C, preferably 200 to 300°C. The higher the reaction temperature, the higher the removal rate of NH4+ ions and NO3- ions, and the shorter the residence time of wastewater in the reaction tower. It may be determined by comprehensively considering the type, degree of processing required, operating costs, construction costs, etc. Incidentally, in order to maintain the liquid phase, a small amount of gas sufficient to exceed the saturated vapor pressure may be present in the reaction tower, and examples of such gas include nitrogen.

The above thermal decomposition reaction decomposes NH4+ ions and N09- ions, especially NO3- ions, in the wastewater to a high degree.

(B) Wet oxidative decomposition step In the first method of the present application, the treated water in the wet pyrolysis step is subsequently subjected to wet oxidative decomposition in order to further decompose and remove NH, + ions, organic substances, and inorganic substances in the treated water.

Wet oxidation is carried out at a pH of about 1 to 11.5, more preferably 3 to 11.5.
9 to progress efficiently.

The catalytically active components used in wet oxidation include those similar to those used in wet pyrolysis. Further, by using co-catalyst components such as tellurium, selenium, and lanthanum in combination with these catalytically active components, the treatment effect can be further improved. The catalyst carrier, the amount of the catalytically active component supported on the carrier, the shape and dimensions of the catalyst, the method of use, etc. may be the same as in the wet thermal decomposition step (A).

This wet oxidation process (B) is essentially different from the wet pyrolysis process (A) of wastewater containing NH and NO3.
One to 1.5 times the theoretical amount of oxygen required to decompose H,+ ions is required.

The gas used as the oxygen source includes air, oxygen-enriched air, oxygen, and at least one impurity such as hydrogen cyanide, hydrogen sulfide, ammonia, sulfur oxides, organic sulfur compounds, nitrogen oxides, and hydrocarbons. Examples include oxygen-containing waste gas. The amount of supply of these gases is such that ammonia, organic substances, and inorganic substances (if waste gas is used as an oxygen source, additionally contained impurities) are mixed with N2, C, and
It is determined based on the theoretical oxygen required for decomposition into O2 and N20, and more preferably 1.0 of the theoretical oxygen amount.
Make sure that 5 to 1.2 times as much oxygen is present in the reaction system. When oxygen-containing waste gas is used as an oxygen source, harmful components in the gas are also decomposed and rendered harmless. Oxygen-containing gas is
- It may be supplied at once, or it may be supplied in multiple doses.

The temperature in the wet oxidation step is also about 100 to 370°C, more preferably about 200 to 300°C.

Moreover, the pressure may be a pressure at which the treated water maintains a liquid phase.

■0 First invention of the present application A) Wet pyrolysis process In the second method of the present application, 0.1 <NH3-N/N03-N
NH4 with ammonia added so that ≦2 (molar ratio)
The NO3-containing wastewater is subjected to wet pyrolysis under the same conditions as in the first invention.

The reaction when ammonia is added to NH4NO3-containing wastewater is expressed by the following formula (1).

NH,, No3+2/3 No3+2 /3 N2 +3 N20 (1) However, if a small amount of oxygen is dissolved in the NH4NO3-containing wastewater from the beginning, it is assumed that some of the following reactions are also taking place. .

NH4No3,000NH3″ +1/402→3/2 N2
+1/2 N20 (2) (B,) Wet oxidation decomposition step In the second method of the present application, the treatment liquid from the above wet pyrolysis step is subjected to wet oxidation treatment under the same conditions as in the first method of the present application.

■9 First Invention A) Wet Pyrolysis Process In the third method of the present application, NH4NO3-containing wastewater to which an acid or a substance that generates an acid under treatment conditions (acid-generating substance) is added to the same method as in the first invention of the present application. Subject to wet pyrolysis under conditions.

Examples of acids used include sulfuric acid, nitric acid, and hydrochloric acid, with sulfuric acid being the most preferred. Examples of acid generating substances include sulfur and sulfur compounds (thiourea, thiosulfuric acid, thiocyanic acid, thioether, thiophenol, etc.). Alternatively, sulfur compound-containing wastewater discharged from a coke oven gas purification device or the like may be used as the source of the acid generating substance.

Nitric acid and substances that can form nitric acid are NO3- in wastewater.
Since it increases the amount of ions, it is preferable to use it in combination with sulfuric acid or as an added component to wastewater with a high content of COD components. Furthermore, although hydrochloric acid and substances capable of forming hydrochloric acid are effective in decomposing nitrogen compounds, their ability to decompose COD components is slightly inferior to that of other acids. The amount of these acids and acid-forming substances added to the NH4NO3-containing wastewater is approximately equal to the total number of moles of alkali metal salts or ions such as NaXK contained in the glass water.

(B) Wet oxidation decomposition step In the third method of the present application, the treatment liquid from the wet pyrolysis step 2 is subjected to wet oxidation treatment under the same conditions as in the first method of the present application.

■1 First invention of the present application A) Wet pyrolysis step In the fourth method of the present application, 0.1. <NH3N/NO3-N
NH4No3 to which ammonia is added and at least one of an acid and an acid-generating substance is added so that the molar ratio is ≦2 (molar ratio)
The containing wastewater is subjected to wet pyrolysis under the same conditions as in the first method of the present application. A. The amount of ammonia added is the same as in the wet oxidation step of the second method of the present application, and the acid, acid-generating substance, and the amount added are the same as in the wet oxidation step of the third method of the present application. It is.

(B) Wet oxidative decomposition step In the fourth method of the present application, the treatment liquid from the wet pyrolysis step 2 is subjected to wet oxidation treatment under the same conditions as in the first method of the present invention.

The present invention will be described in more detail below with reference to the drawings.

FIG. 1 shows a flowchart of one embodiment of the method of the invention.

In Figure 1, wastewater raw water contained in a tank (1) passes through a line (3) and is sent to a heat exchanger (9) via a line (7) by a booster pump (5), and is then sent to a heat exchanger (9) using a wet oxidation method as described below. After being heated by the high-temperature treated water from the decomposition reaction tower (23), it is fed through a line (11) to a heater (15) attached to a boiler (13), where it is heated to a predetermined temperature. . When a steady state is reached in which the reaction can maintain a predetermined temperature, heating by the boiler (13) is stopped. The wastewater heated to a predetermined reaction temperature then passes through a line (17) and enters a wet pyrolysis reaction tower (19) containing a supported catalyst, where it is subjected to wet pyrolysis treatment in the absence of oxygen. . The high-temperature treated water subjected to the wet pyrolysis treatment is then supplied to the wet oxidation decomposition reaction tower (23) containing the supported catalyst through the line (21), and then to the line (25) through the air compressor (24). ) is subjected to wet oxidative decomposition in the presence of an oxygen-containing gas (air in the drawing) supplied from In order to improve the gas-liquid contact efficiency in the wet oxidative decomposition reaction tower (23) and increase the wet oxidative decomposition reaction rate, it is preferable to make the bubbles during gas-liquid mixing fine. Such a bubble refinement method is described, for example, in Japanese Patent Application Laid-Open No. 49-1999.
No. 49873, Japanese Unexamined Patent Publication No. 4'149874, etc. The high-temperature treated water subjected to wet oxidative decomposition is sent to the heat exchanger (9) via the line (27), where it undergoes preliminary treatment of raw wastewater, and then passes through the line (29) to the cooler (31). ) and cooled. A water supply line (33) and a drain line (35) are connected to the cooler (31), and cooling water is constantly supplied and drained. The treated water leaving the cooler (31) is transferred to the line (37)
The liquid is sent to the gas-liquid separator (39), where it is separated into a liquid phase from line (41) and a gas phase from line (43).

If the pH of the liquid phase is too low, a pn adjuster (in the illustrated embodiment, an aqueous NaOH solution) is added from line (45) and then removed from the system via valve (47). On the other hand, the gas phase from the line (43) is transferred to the valve (49).
) and then taken out of the system.

In addition, by attaching a temperature detection device (51) to the wet oxidative decomposition reaction tower (23), the valve (53) is opened depending on the temperature inside the reaction tower (23), and the line (7) is opened.
A portion of the wastewater passing through can be directly fed to the wet pyrolysis reaction tower (19) via a bypass line (55).

In addition, in order to control the pressure inside the system during reaction processing, a pressure detection device (57) is attached to the gas-liquid separator (39), so that the pressure inside the gas-liquid separator (39) can be adjusted. depending on,
The degree of opening and closing of the valve (49) can be adjusted.

In the second invention of the present application, when ammonia is added to wastewater, it may be mixed with the wastewater passing through the line (3) from the line (59), for example. The location at which ammonia is added to the wastewater prior to the wet pyrolysis treatment is not particularly limited and can be added at any location.

Further, in the third invention of the present application, when adding an acid or an acid generating substance to wastewater, the line (61) to the line (3)
) can be mixed with the wastewater passing through it.

The location at which the acid or acid-generating substance is added to the wastewater prior to the wet pyrolysis treatment is also not particularly limited, and it can be added at any location.

Furthermore, in the fourth invention of the present application, when adding ammonia and acid or an acid generating substance to the wastewater, the line (59) and the line (61) are connected to the line (59) and the line (61), respectively.
3) It can be supplied to the wastewater flowing inside.

Also in the second to fourth inventions of the present application, the treated water after the wet pyrolysis treatment is subjected to the wet oxidative decomposition treatment in the same manner as in the first invention of the present application.

Effects of the Invention According to the present invention, wastewater containing a high concentration of NH4NO3 can be efficiently treated, and the concentrations of NH, l+ ions and NO, - ions can be significantly reduced. Therefore, for example, wastewater discharged from a uranium raw material treatment process or a spent uranium fuel reprocessing process and whose NH4NO3 concentration can reach 10% or more can be easily treated using simple equipment.

EXAMPLES Hereinafter, examples will be shown to further clarify the features of the present invention.

Example 1 (a) Wet pyrolysis; pH 10, NH4NO3 concentration 10% (NH3-N/N0
3-N=1) (7) 100ml of wastewater to a volume of 300ml
Housed in a stainless steel autoclave with 25
Thermal decomposition treatment was carried out at 0°C for 60 minutes. The reactor is filled with a catalyst Log with a diameter of 5 mm in which ruthenium 2% is supported on a titania carrier, and the pressure inside the reactor is 70 kg.
/clfI-G.

(b) Wet oxidative decomposition; Next, air in an amount equivalent to 1.1 times the theoretical oxygen amount was charged into the autoclave that had completed the wet pyrolysis step, and wet oxidation treatment was performed for 30 minutes. Other conditions during the wet oxidation treatment were the same as those during the wet pyrolysis.

The decomposition rates of total nitrogen components after (a) wet thermal decomposition and (b) wet oxidative decomposition are shown in Table 1 together with the results of Examples 2 to 12 and Comparative Examples 1 to 2.

Example 2 Wet pyrolysis of N, H, NO3-containing wastewater in the same manner as in Example 1 except that sulfuric acid (0,012 mol/Q) equivalent to Na and K in the wastewater was added to the NH, NO3-containing wastewater. treatment and wet oxidation treatment.

Examples 3 to 6 A predetermined amount of NH,,OH was added to the same NH4NO3-containing wastewater as that thermally decomposed in Example 1 to produce NH3-N/N03-N.
After adjusting the molar ratio, thermal decomposition treatment and wet oxidation treatment were performed in the same manner as in Example 1.

Example NH4NO3-containing wastewater was thermally decomposed and subjected to wet oxidation treatment in the same manner as in Example 1, except that a catalyst with a diameter of 5 mm in which 1% by weight of palladium was supported on a titania carrier was used in place of the fluthenium supported catalyst. Ta.

Examples 8-11 Thermal decomposition treatment of N H4N O3-containing wastewater in the same manner as Examples 3-6 except that a catalyst with a diameter of 5+n+n in which 1% by weight of palladium was supported on a titania carrier was used instead of the ruthenium-supported catalyst. and wet oxidation treatment.

Comparative Example 1 NH4N was prepared in the same manner as in Example 4 except that no catalyst was used.
o. The contained wastewater was subjected to thermal decomposition treatment.

Comparative Example 2 Thermal decomposition treatment of NH4N03-containing wastewater was carried out in the same manner as in Example 4, except that titania spheres with a diameter of 5 mm that did not support a catalytically active component were used in place of the ruthenium-supported catalyst.

Example] 2 Wet pyrolysis treatment of NH4N03-containing wastewater and Wet oxidation treatment was performed.

In addition, in Table 1 and the following tables, (a) and (b)
) indicate the results after wet pyrolysis and wet oxidative decomposition, respectively.

Table 1 Actual age Catalyst activity NTo -N/ NO3-N component
(Molar ratio) I Ru 1 2 Ru 1 3 Ru 1. 3 4 Ru 1.7 5 Ru 2.0 6 Ru 2. 5 7 Pd 1.0 Total nitrogen component decomposition $ (%) (a) (b) (continued) N Total nitrogen component decomposition i (%) (a) (b) 92 >99 Table 1 Nlh -N/N03 ( Molar ratio) 1.3 1.7 2.0 2.5 1.7 Example Catalyst active component 8' Pd 9 Pd 10 Pd 11 Pd 12 R'u Comparative example 1 1.7
4.0 6.92 Ti carrier 1.7 4.2 7.
4 Examples 13 to 19 Thermal decomposition treatment and wet oxidation treatment of NH4NO3-containing wastewater were carried out in the same manner as in Example 1, except that the N H4N O3 concentration and pH of the wastewater and the catalytic active component were changed as necessary. The results are shown in Table 2.

Table 2 Example M Medium activity N03 NO4 Total nitrogen component decomposition rate (%) Concentration (%) pH<a)
(b) 13 Ru 1.
9.2 72 9814
Ru 4 9.4 8
2 9915 Ru
7 9.4 83 9916
Ru 10 9.6
8.3 >9917 Pd
1 9.2 78
9918 Pd 4
9.4 84>9919 Pd
7 9.4. 85>99
Example 20 Wastewater (NH3
N/NO3N=1)l;l: Add NH4OH and -cN
H3-N/NO3-N=1.7+: Adjust and
Sulfuric acid was added at a rate of 0.01 mol/Q to adjust the pH to 9.
．． It was set as 2. This wastewater is then subjected to a space velocity of 6. 31/
hr (empty column standard) was supplied to the lower part of a high nickel steel cylindrical reactor, and thermal decomposition treatment was performed for 4000 hours.

The mass velocity of the liquid is 2.8 ton/m2・hr, and the reactor is filled with a spherical catalyst with a diameter of 5 mm in which 2% by weight of palladium is supported on a titania carrier. was 250°C and 70 kg/cm2.

Next, the theoretical amount of oxygen was added to the reactor after the thermal decomposition process.
．． Wet oxidation treatment was carried out by charging air in an amount equivalent to 1 times the amount and setting the space velocity to 10.2'/hr. Other conditions during the wet oxidation treatment were the same as those during thermal decomposition.

After the gas-liquid mixed phase after the reaction is completed is subjected to heat recovery, it is led to a gas-liquid separator to separate the generated nitrogen gas, and the separated gas and liquid phases are indirectly cooled and then taken out of the system. Ta.

Table 3 shows the decomposition rates of N H3, N O3 and total nitrogen components.

CODM9 and TOC were not detected in the liquid phase after gas-liquid separation.

Furthermore, NOx and SOx were not detected in the gas phase either.

Table 3 shows the decomposition rates of NH3, NO3 and total nitrogen components.

NH3 Decomposition rate (%) (a) 85 (b) >99 Part 3 O3 Decomposition rate (%) 〉99 table Total nitrogen content Decomposition rate (%) 〉99 The wastewater was treated in the same manner as in Example 20.

The results are shown in Table 4.

*Properties of wastewater and reaction conditions: NH4NO3 concentration -5% pH = 9. 9 Total nitrogen concentration - 17,500 mg/Q Temperature - 270°C Pressure - 90 kg/cd Space velocity of waste water - 1,5'/hr (same for both wet pyrolysis and wet oxidative decomposition) Example 21
~37 Using the following wastewater and adopting the reaction conditions,
The catalyst (same for both wet pyrolysis and wet oxidative decomposition) was added to the fourth
Table 4 Table 4 (continued) 2%Ru-TiO2 2%Ru-Zr02 1%Rh-Ti02 1%0s-TiO3 1%Ir-TiO2 0.3%Pt, ( iCh 1%Au-TiO2 5%Fe TiO2 5%Ni-Ti0□ 5%W -TiO2 10%Mn-TiO2 5%Mn・5%Ce-'lIO2 〉99 〉99 〉99 33 5%Cu-Ti0770 3410% Co-Ti0284 35 5%Ce・5%Ce-Ti028536 5
%C0・5%Te-TiO2853715%MgTi
O273

[Brief explanation of drawings]

FIG. 1 is a flowchart outlining the method of the present invention. (1)...Wastewater tank (5)...Boost pump (9)...Heat exchanger (13)...Boiler (15)...Heater (19)...Wet pyrolysis reaction Tower (23)...Wet oxidation reaction tower (24)...Air compressor (25)...Air supply line (31)...Cooler (33)...Water supply line (35)... Drainage line (39)... Gas-liquid separator (41)... Liquid phase line (43)... Liquid H phase in (43)... Temperature detection device (45)... pH adjuster Supply line (51)...Pressure detection device (55)...Bypass line (59)...Ammonia supply line (61)...Acid or acid generating substance supply line (and above)

Claims (1)

[Claims] [1] Ammonium nitrate-containing wastewater is treated in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, insoluble or poorly soluble compounds thereof, and base metals, and in the absence of oxygen. pH about 1-11.5, temperature 100-
After wet thermal decomposition at 370°C, the treatment liquid is treated in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, insoluble or poorly soluble compounds thereof, and base metals, and ammonia and organic Wet oxidation at a pH of about 1 to 11.5 and a temperature of 100 to 370°C in the presence of a gas containing 1 to 1.5 times the theoretical amount of oxygen required to decompose organic and inorganic substances. A method for treating wastewater containing ammonium nitrate. [2] Ammonium nitrate-containing wastewater to which ammonia has been added so that 0.1<NH_3-N/NO_3-N≦2 (molar ratio) After wet pyrolysis at a pH of approximately 1 to 11.5 and a temperature of 100 to 370°C in the presence of a supported catalyst containing one type of active ingredient and in the absence of oxygen, the treatment liquid is treated with noble metals and their insoluble or sparingly soluble compounds. and the theoretical amount of oxygen necessary to decompose ammonia, organic substances, and inorganic substances in the treatment liquid in the presence of a supported catalyst containing at least one selected from the group consisting of base metals as an active ingredient. A method for treating ammonium nitrate-containing wastewater, which comprises carrying out wet oxidation at a pH of about 1 to 11.5 and a temperature of 100 to 370°C in the presence of a gas containing five times as much oxygen. [3] Ammonium nitrate-containing wastewater to which at least one of an acid and an acid-generating substance has been added is mixed with oxygen in the presence of a supported catalyst containing at least one selected from the group consisting of noble metals, insoluble or poorly soluble compounds thereof, and base metals as an active ingredient. pH about 1-11.5, temperature 100-370°C in the absence of
After wet thermal decomposition, the treatment solution is treated in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, insoluble or poorly soluble compounds thereof, and base metals, and in the presence of ammonia and organic substances in the treatment solution. and in the presence of a gas containing 1 to 1.5 times the theoretical amount of oxygen required to decompose the inorganic substance at a pH of approximately 1 to 11.5 and a temperature of 100 to 100.
A method for treating wastewater containing ammonium nitrate, characterized by wet oxidation at 370°C. [4] Ammonium nitrate-containing wastewater to which ammonia and at least one acid and acid-generating substance have been added so that 0.1<NH_3-N/NO_3-N≦2 (molar ratio) is pH of about 1 to 1 in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of soluble compounds and base metals and in the absence of oxygen.
1.5. After wet pyrolysis at a temperature of 100 to 370°C, the treatment liquid is treated in the presence of a supported catalyst containing at least one active ingredient selected from the group consisting of noble metals, insoluble or poorly soluble compounds thereof, and base metals. pH in the presence of a gas containing 1 to 1.5 times the theoretical amount of oxygen required to decompose ammonia, organic substances, and inorganic substances in the treatment solution.
1 to 11.5 and wet oxidation at a temperature of 100 to 370°C.