JP2003175385A - Method for cleaning ammonia-containing wastewater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning ammonia-containing wastewater by efficiently diffusing ammonia therefrom. <P>SOLUTION: The dissipation of ammonia from ammonia-containing wastewater is performed under reduced pressure. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to an ammonia-containing wastewater.
To a purification method. [0002] 2. Description of the Related Art Ammonia is released from wastewater containing ammonia.
It is generally known to disperse and purify. For example,
For wastewater containing hydrogen peroxide and ammonia,
Decomposes hydrogen hydride in the presence of a catalyst while releasing ammonia
A method of purifying by separating and removing by treatment is disclosed in Japanese Patent Laid-Open No. 5-26.
No. 9475, JP-A-11-290870, etc.
It is described in. [0003] However, in the above publication,
Ammonia emission under general conditions as listed
I was able to remove ammonia enough
Not much ammonia in the treated water after the emission treatment
There was a problem of remaining. [0004] Accordingly, the present invention is directed to wastewater containing ammonia.
Provides a method for purifying ammonia by efficiently diffusing it
Is to try. [0005] [Means for Solving the Problems] According to the research of the present inventors,
By performing the ammonia emission treatment under reduced pressure,
It turns out that the purpose can be achieved. That is, the present invention relates to an ammonia-containing wastewater.
When purifying ammonia by releasing it from
Ammonia-containing waste characterized by performing treatment under reduced pressure
It is a water purification method. [0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Wastewater containing ammonia (hereinafter sometimes simply referred to as “wastewater”).
You. ) Is not particularly limited, and wastewater containing ammonia
Any may be used. In addition, for example, Ammoni
Nitrogen-containing organic substances that can be released together with ammonia during emission
Compounds such as dimethylamine, trimethylamine
Any may be contained. [0008] There is no particular limitation on the ammonia concentration in the wastewater.
However, the method of the present invention has an ammonia concentration of 200 mg /
L (liter; the same applies hereinafter), and more preferably 500 to 1
Waste with high ammonia concentration such as 00,000 mg / L
It is suitably used for water purification. Note that, in the present invention,
Monia is molecular ammonia dissolved in wastewater
(NH₃), As well as ammonium ions
For example, NH₄OH, (NH₄)₂SO₄, NH₄
It also means Cl or the like. In the present invention, the ammonia emission treatment is
Add metal such as stainless steel, plastic or
Lamic mesh, granule, ring, or c
Fills a structure such as a honeycomb and empties as a gas for emission
Gas, inert gas such as nitrogen, or steam
Do. Raschig ring, ball phosphorus
, Interlock saddle, IMTP, cascade mini
Random packing such as rings, metallets, terrarets,
Regular packing such as Sulzer packing can be used.
Wear. Among them, plastics such as polypropylene
Filling materials are cheap and resistant to corrosion by chlorine etc.
There are advantages. The ammonia emission treatment is preferably performed under reduced pressure.
Is -50 to -0.5 kPa (gauge pressure), more preferably
Is to be performed under a pressure of -15 to -1 kPa (gauge pressure)
Except for this point, it is conventionally used for ammonia emission.
It can be carried out under the conditions set forth. For example, for radiation
If steam is used as the gas,
To a temperature below 100 ° C., preferably 90 ° C.
The temperature is preferably adjusted to not less than 100 ° C and less than 100 ° C. Pressure in the stripping tower
By adjusting the force and temperature to the above range, the wastewater
Can be more efficiently dissipated. Before the ammonia emission treatment, an alkaline substance
Quality, for example sodium hydroxide, to add ammonia
Adjusting the pH of wastewater to a range of 10 to 13 is an ammo
This is suitable in that the near-emission efficiency is increased. There are small gaps in the stripping tower and piping.
If the pressurizing operation is performed,
Near odor leaks, but in the decompression operation, the air is sucked in reverse
Therefore, it is suitable for environment and safety. [0013] Since the temperature inside the stripping tower is low, polypropylene
Even if plastic fillers such as
Economically effective because the frequency of filling changes is reduced.
Be profitable. In addition, the amount of heat dissipation is reduced, and the required heat insulating material is also reduced.
it can. Therefore, according to a preferred embodiment of the present invention,
If chlorine ion (Cl⁻) Etc.
Made of waste water filled with plastic filler
(A) Supply to the stripping tower, where ammonia is removed under reduced pressure
By using water vapor as a gas for emission.
Ammonia at a temperature of 90 ° C or higher and lower than 100 ° C under reduced pressure
Efficient for a long time by performing radiation treatment, and
It is industrially advantageous to purify ammonia-containing wastewater.
it can. Regarding the amount of gas used for emission,
If air or nitrogen gas is used as the source,
100 to 10,000 times (capacity) of incoming wastewater,
Preferably, it is 1,000 to 5,000 times (capacity)
Is good. When performing emission treatment using steam,
0.05 to 10 times (mass) of wastewater to be introduced, preferred
Preferably, it is 0.1 to 1 times (mass). Emission gas
By adjusting the supply amount of wastewater to the above range,
It is possible to disperse the ammonia more efficiently. Said
As described above, when operating under reduced pressure, ammonia is efficiently removed.
Compared to conventional pressurized operation.
Reduced usage, especially air, nitrogen gas or steam
In the case of running costs can be reduced
You. As a representative example of the above ammonia-containing wastewater,
Is a wastewater containing hydrogen peroxide and ammonia,
Ammonia-containing wastewater after decomposing and removing hydrogen peroxide
I can do it. The present invention relates to such hydrogen peroxide.
Suitable for purification of wastewater containing ammonia
You. Regarding the concentration of hydrogen peroxide in wastewater,
There is no particular limitation similarly to the concentration of monia, but the method of the present invention
Means that the concentration of hydrogen peroxide is 500 mg / L or more,
Peroxide water such as 1,000-100,000 mg / L
It is suitably used for purification of wastewater having a high element concentration. The hydrogen peroxide in the wastewater is, for example, water peroxide
Decomposes efficiently by contacting
Can be. The catalyst for decomposing hydrogen peroxide includes peroxide
It is possible to use a commonly known catalyst for hydrogen decomposition.
Wear. For example, activated carbon or white as a catalytically active component
Gold, palladium, rhodium, iridium, ruthenium,
Cobalt, manganese, copper, nickel, etc.
Tania, zirconia, iron oxide, ceria, silica, silica
-Do not support on metal oxides such as alumina and silicon carbide.
Supported catalysts. Among them, activated carbon,
Alternatively, titanium, zirconium, iron or iron may be used as the first component.
At least one member selected from the group consisting of
A metal oxide and platinum, palladium as a second component,
From the group consisting of iridium, ruthenium and manganese
At least one selected metal and / or metal oxide
Is preferably used. further,
Metal such as stainless steel, plastic or ceramic
Structures such as mixed mesh, granular, and honeycomb
What gave catalytic activity to the structure can also be used. The above structure
The body itself has hydrogen peroxide decomposition activity
However, in general, the catalytic activity is imparted to the structure
A method for supporting a solvent-active component, or a chemical solution treatment on a structure
This can be achieved by performing treatment, firing, and the like. The above structure
Specifically, for example, Raschig ring, ball
, Interlock saddle, IMTP, cascade
Irregular filling of niring, metalette, teralet, etc.
And structured packing such as Sulzer packing. Peracid in the presence of the above hydrogen peroxide decomposition catalyst
There are no particular restrictions on the conditions for the decomposition of hydrogen hydride.
It can be carried out under the conditions specified. Specifically
Is, for example, 20 ° C. or more and less than 100 ° C., preferably 20 ° C.
~ 95 ° C, more preferably 30 ~ 85 ° C, 20k
Decomposes hydrogen peroxide at pressures below Pa (gauge pressure)
be able to. Waste containing hydrogen peroxide and ammonia
For example, water is subjected to ammonia treatment under reduced pressure to remove ammonia.
Removal step (ammonia release step) and hydrogen peroxide
Step of decomposing and removing hydrogen peroxide by contacting with a decomposing catalyst
Hydrogen oxide decomposition step)
can do. Ammonia emission process and hydrogen peroxide content
The order of the solution steps can be determined as appropriate. After the above-mentioned ammonia emission treatment, the ammonia
The ammonia-containing gas discharged from the near
Near cracking equipment, especially ammonia catalytic cracking tower
Even if it is released, or
Monia may be recovered. The catalytic decomposition of ammonia
Commonly used method for recovery of ammonia and ammonia
And can be carried out under known conditions. In the ammonia decomposition apparatus, the following equation is used.
Ammonia is oxidatively decomposed into nitrogen and water. NH₃+ (3/4) ・ O₂  → (1/2) ・ N₂+ (3
/ 2) · H₂O When using nitrogen or water vapor as the gas for emission,
Oxygen-containing gas is added to the ammonia-containing gas discharged from the stripping tower.
(E.g., air)
What is necessary is just to introduce it. As the above-mentioned ammonia decomposition catalyst, ammonia
The use of commonly known catalysts for the decomposition of near
it can. Titania, silica, zirconia, alumina, ba
Nadium, tungsten, molybdenum, cerium, iron,
Platinum, palladium, iridium, rhodium, ruthenium
Manganese, chromium and copper
Use of at least one metal or its oxide
And preferably, titania, silica, zirconium and
At least one kind of gold selected from the group consisting of
A component which is a metal oxide or a metal composite oxide, and vanadium
, Tungsten, molybdenum, cerium and iron
At least one metal oxide selected from the group consisting of
B component, platinum, palladium, iridium, rhodium
Group consisting of ruthenium, ruthenium, manganese, chromium and copper
At least one metal or oxide thereof selected from
Catalysts containing certain C components are preferred. [0024] According to the method of the present invention, ammonia-containing
Ammonia can be efficiently released from wastewater
You. [0025] EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples.
explain. Example 1 Ammonia nitrogen 4,000mg / L, sodium chloride
The synthetic wastewater containing 400 mg / L is shown in the system diagram shown in FIG.
It was processed. The synthetic waste water is supplied from a waste water tank 1 to a pump 2
7000 kg / h at a flow rate of
After heating to 80 ° C with polypropylene pole inside
Ring (nominal size 25mm) 1.6m³Dispersion filled
Column 8 was fed from the top. In addition, in front of the heater 7
1.0 kg / h of 25 mass% aqueous sodium hydroxide solution
The pH was adjusted to 11.8 by addition at a flow rate. In the lower part of the stripping tower 8, 0.2
Supplying steam (MPa (gauge pressure)) at 850 kg / h
Was. The pressure in the stripping tower 8 is determined by ammonia decomposition as described later.
Suction with a blower 20 attached to the reactor 18
, The pressure was maintained at -2 kPa (gauge pressure). Radiation tower
The temperature in the packed bed of No. 8 was 95 to 99 ° C. In the lower part of the stripping tower 8, a liquid level controller (L
C) to detect the liquid level, and to maintain a constant liquid level.
The treated water was discharged at the pump 13. The treated water discharged in the stripping tower 8 is cooled.
After cooling to 40 ° C in step 12, discharge from line 14 out of the system
did. The ammonia content in the discharged treated water is below the detection limit
Below (less than 1 mg / L). On the other hand, the ammonia-containing gas is supplied to the tower 8
From the top via the line 15 and the air heated by the heater 16
8,000 ppm ammonia concentration by mixing
(Capacity). Thereafter, 350
° C and introduced into the ammonia decomposition reactor 18
Decomposition of ammonia was performed. As the ammonia decomposition catalyst, Ti
-Si composite oxide: V₂O₅: WO ₃: Pd = 89.
1: 6.9: 3: 1 (mass ratio) and BET ratio
Surface area 120m2 / g, pore volume 0.45cc / g
A medium was used. The gas from the ammonia decomposition reactor 18 is
Sucked by the blower 20 through
I released it to my mind. When the released gas was analyzed,
Monia was 3 ppm and nitrogen oxide was 8 ppm. No odor was felt near the apparatus. Book
After operating the equipment continuously for one year, shut down the equipment.
Inspection of the equipment revealed that the filling
There was no deformation and no need for replacement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram of one embodiment of the present invention. [Explanation of symbols] 1 wastewater tank, 8 ammonia stripping tower, 18 ammonia decomposition tower

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Claims (1)

Claims: 1. A method for purifying ammonia-containing wastewater, wherein the ammonia-containing wastewater is purified by decompressing the ammonia-containing wastewater.