JP2000288538A - Treating method for nitrogen-containing wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a stable treatment over a long period of time by preventing the scale generation in a treating device or a catalyst which is used in removing ammonia nitrogen from wastewater containing both ammonia nitrogen and hardness components (Ca, Mg) with an ammonia stripping method or a catalytic oxidation method, and to reduce the costs by decreasing a maintenance frequency of the treating device or catalyst. SOLUTION: Wastewater 2 in which ammonia nitrogen coexists with hardness components is brought into contact with a cation exchange resin columns 4 and 6 to remove the hardness components contained in the wastewater. Subsequently, the wastewater is treated with an ammonia nitrogen removing device 28 employing an ammonia stripping method or a catalytic oxidation method to remove the ammonia nitrogen. It is desirable to use a weak acid cation exchange resin as the cation exchange resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing ammonia nitrogen in waste water by treating ammonia waste nitrogen-containing waste water by an ammonia stripping method or a catalytic oxidation method. And a hardness component (Ca, Mg). As waste water in which ammonia nitrogen and a hardness component coexist, for example, in a factory or a power plant that uses ammonia, when ammonia is supplied to an ammonia storage tank, the ammonia discharged to the outside of the tank through a safety valve of the tank is used. The contained gas is C
Wastewater generated when washed and absorbed with industrial water containing a ²⁺ or Mg ²⁺ .

[0002]

2. Description of the Related Art Some wastewater discharged from power plants and various industrial plants contains ammonia nitrogen. At present, there is no regulation of ammonia nitrogen by drainage standards for all water areas, but in recent years the problem of eutrophication in closed water areas has become serious, and as a result, wastewater quality regulations for ammonia nitrogen have been active. Is becoming

Conventionally, biological nitrification and denitrification has been generally used as a method for removing ammonia nitrogen in wastewater. However, this biological treatment requires a large installation space, which is difficult to control. Because it is necessary to treat generated sludge and is not suitable for treating high-concentration ammonia-nitrogen-containing wastewater (it is limited to remove 500 mg / L of ammonia-nitrogen). A new ammonia nitrogen removal method that is an alternative to the conventional treatment method is being proposed.

[0004] Regarding the above-described new ammonia nitrogen removal method, various companies have proposed an ammonia stripping method and a catalytic oxidation method (both will be described later) as physicochemical treatment methods. These physicochemical treatment methods are easy to manage, do not require a large installation space,
It has the advantages that no sludge is generated and that wastewater containing high concentration of ammonia nitrogen can be treated.

[0005]

When an ammonia nitrogen-containing wastewater is treated by an ammonia stripping method or a catalytic oxidation method, if ammonia nitrogen and a hardness component coexist in the wastewater, the scale in a treatment apparatus or a catalyst is reduced. The problem of occurrence arises. That is, in any of the above-mentioned methods, when hardness components such as Ca and Mg are present in the wastewater, these components are precipitated as scales in the processing apparatus (heat exchanger, heater, processing tank, piping, etc.), Hinders stable operation of the vehicle. Further, in the catalytic oxidation method, a hardness component adheres and precipitates as a scale on the surface of the catalyst, which acts as a catalyst poison or causes the catalysts to adhere to each other, thereby deteriorating the catalytic performance. Therefore,
In order to maintain stable treatment, any of the above-mentioned methods requires periodic scale removal in the treatment equipment, and the catalytic oxidation method requires periodic catalyst replacement. Was a heavy burden.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to treat a wastewater in which ammonia nitrogen and a hardness component coexist by an ammonia stripping method or a catalytic oxidation method. It is an object of the present invention to provide a method for treating nitrogen-containing wastewater, which can prevent the generation of scale in a catalyst and can continue stable treatment for a long period of time, and can reduce costs by reducing the frequency of maintenance of a treatment apparatus and a catalyst. Aim.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for removing ammonia-containing nitrogen in wastewater by treating ammonia-containing nitrogen-containing wastewater by an ammonia stripping method or a catalytic oxidation method. There is provided a method for treating nitrogen-containing wastewater, wherein the wastewater is brought into contact with a cation exchange resin to remove hardness components in the wastewater, and then treated by the ammonia stripping method or the catalytic oxidation method.

In the present invention, after the hardness components (Ca, Mg) in the wastewater are removed in advance by ion exchange, the wastewater is treated by an ammonia stripping method or a catalytic oxidation method.
Therefore, at the time of the treatment by these methods, the hardness component is not contained in the water to be treated, and therefore, it is possible to prevent the generation of scale in the treatment apparatus or the catalyst of the ammonia stripping method or the catalytic oxidation method.

Hereinafter, the present invention will be described in more detail. In the present invention, first, the ammonium-nitrogen-containing wastewater is brought into contact with a cation exchange resin to remove hardness components in the wastewater. In this case, the type of the cation exchange resin is not limited as long as the hardness component in the waste water can be removed, but it is more preferable to use a weakly acidic cation exchange resin. The reason that the weakly acidic cation exchange resin is preferable is that the ion exchange capacity is larger than that of the strongly acidic cation exchange resin, and regeneration with an acid is easy (regeneration with a small amount of a regenerating agent). However, a strongly acidic cation exchange resin can adsorb Ca ²⁺ and Mg ²⁺ regardless of the pH of the wastewater, whereas a weakly acidic cation exchange resin requires Ca if the pH of the wastewater is not alkaline. ²⁺ and Mg ²⁺ cannot be adsorbed. Therefore, when a weakly acidic cation exchange resin is used, the pH of the wastewater is adjusted to about 9 to 12, and then the wastewater is brought into contact with the weakly acidic cation exchange resin.

Regarding the ionic form of the cation exchange resin,
Any ion type other than the Ca type and the Mg type may be used.
The form, NH ₄ form or alkali metal ion form (Na form, K form, etc.) is preferred.

As a specific example of the cation exchange resin used in the present invention, a strongly acidic cation exchange resin is Amberlite (registered trademark, hereinafter the same) IR120B, IR124, 200
C, Diaion (registered trademark, the same applies hereinafter) SK1B, S
Examples of weakly acidic cation exchange resins such as K102, PK208 and PK212 include Amberlite IRC50, IRC76, Diaion WK10, WK20 and the like.

[0012] In the present invention, there is no limitation on the configuration of the apparatus for bringing the ammonium-nitrogen-containing wastewater into contact with the cation exchange resin, and a single-column system using only one ion-exchange resin column may be used. A multi-tower system in which water is passed through the ion-exchange resin tower may be used. It is particularly preferable to connect two or more ion-exchange resin towers in series, and to perform a water-passing treatment by a merry-go-round method. The merry-go-round method refers to, for example, when three ion exchange resin towers are connected, the concentration of a hardness component (for example, calcium concentration (or calcium hardness)) contained in the first (the most upstream side in the water flow direction) treated water. When the magnesium concentration (or magnesium hardness) or the total hardness, which is the sum of the two hardnesses, exceeds a predetermined value, the ion exchange resin of the first column is regenerated, and then the regenerated column is passed through the column in the water direction. Connect to the downstream side and supply the water to be treated to the second tower → 3
This is a maintenance method in which water flows in order from the first tower to the first tower.

In the present invention, when the merry-go-round method is employed for the ion exchange treatment, the cation exchange resin in the first column is regenerated when the cation exchange resin in the first column becomes substantially saturated with the hardness component. By doing so, it is possible to prevent ammonia-nitrogen from being mixed into the regeneration waste liquid as much as possible. The reason is as follows. That is, since NH ₄ ⁺ has a lower selectivity to the cation exchange resin than Ca ²⁺ or Mg ²⁺ , NH ₄ ⁺ (the cation exchange resin) adsorbed to the cation exchange resin by the passage of the water to be treated. Is used in the H form or alkali metal form) or NH ₄ ⁺ (when the cation exchange resin is used in the NH ₄ form) which has been adsorbed to the resin from the beginning of water passage is caused by Ca in the water to be treated.
^It is ion-exchanged with ²⁺ and Mg ²⁺ and is pushed to the downstream side. Therefore, when the cation exchange resin is almost saturated with the hardness component while continuing the passage of water, NH ₄ ⁺ is scarcely present in the cation exchange resin at that point. Since NH ₄ ⁺ is scarcely present in the cation exchange resin, it is natural that ammonia nitrogen is hardly mixed in the regenerated waste liquid obtained by regenerating this. If little ammonia nitrogen is mixed in the recycle waste liquid, the recycle waste liquid can be discharged or treated without performing any nitrogen removal treatment.

[0014] Whether the cation exchange resin charged in the first column has almost saturated with the hardness component is determined by
It can be known by monitoring the hardness component concentration in the treated water flowing out of the first tower, and when the hardness component concentration in the treated water, for example, the total hardness becomes almost the same as that of the water to be treated (raw water), it can be known. It may be determined that saturation has been reached.
When the concentration of the hardness component in the water to be treated is substantially constant, the concentration of the hardness component and the ion exchange capacity of the cation exchange resin packed in the tower allow the water to pass until saturation is reached. Since the flow rate of the treated water can be obtained in advance by calculation, it may be determined that the cation exchange resin has almost saturated with the hardness component when the flow rate reaches this calculated amount.

When the merry-go-round system is adopted, even when the cation exchange resin of the first ion exchange resin tower is almost saturated with the hardness component, the second and subsequent ion exchange resin towers still have the hardness component. Has sufficient capacity to remove wastewater, the wastewater can be treated in the second and subsequent ion exchange resin towers even during the regeneration treatment of the first ion exchange resin tower, and the continuous operation of the ion exchange treatment apparatus There is also an advantage that it becomes possible.

On the other hand, when water is passed through a single tower, the water must be stopped when the hardness component starts to leak into the treated water, and the cation exchange resin must be regenerated. In the cation exchange resin, the NH ₄ form still remains. Therefore, when this resin is regenerated, the regeneration waste liquid contains ammonia nitrogen eluted from the cation exchange resin. Therefore, in this case, it is not preferable because a nitrogen removal treatment must be separately performed on the regeneration waste liquid containing the hardness component.

The present invention will be described in more detail.
In the water treated by the ion exchange resin,_Four ⁺Contains
Even if this NH_Four ⁺Is the latter ammonia stripping
The problem is that it is removed by
In other words, in other words, NH in the water to be treated_Four ⁺Is cation exchange
There is no need to remove with a resin. Therefore, for example, H
Exchange treatment in a single tower system using a cation-exchange resin
When carrying out treatment, drain the wastewater containing ammonia nitrogen.
Therefore, initially, the Ca²⁺And Mg²⁺With NH
_Four ⁺Is removed, and a part of the cation exchange resin is NH 3_FourIn shape
However, NH once adsorbed on the cation exchange resin_Four ⁺Is a choice
Ca in the highly treated water to be treated²⁺And Mg²⁺Is ion exchanged with
The water is gradually pushed out to the downstream side, and eventually the treated water
NH in _Four ⁺Will leak. In this state
NH_Four ⁺Hardness components that are more selective than
The ammonia exchange to the ion-exchange resin tower.
The flow of element-containing wastewater can be continued. After that,
Regeneration should be performed when the hardness component starts to leak into the water
No.

When the above-mentioned merry-go-round method is adopted, if the cation exchange resins of all the ion exchange resin towers are initially set to the H-shape and water is started to flow, 1
Th when the ion exchange resin column is NH ₄ ⁺ becomes leak, NH leaked ₄ ⁺ are adsorbed by the ion-exchange resin column of second and subsequent cation exchange resin in the tower gradually NH ₄ from an H-shaped Transition to shape. Then, when the hardness component concentration in the treated water flowing out of the first tower becomes almost the same as that of the raw water, the first tower is separated from the water and the cation exchange resin in the tower is regenerated with acid. When regeneration is completed, connect the tower to the most downstream side, and then continue processing by passing raw water through each tower in turn using the ion exchange resin tower, which was the second most recently used, as the most upstream side tower. Thereafter, such operations are repeated to treat the wastewater containing ammonia nitrogen.

Here, when water supply is resumed with the second ion-exchange resin tower being the uppermost stream side, the cation-exchange resin charged in the second and subsequent towers is almost NH _{4 type} . However, as described above, the hardness component in the raw water is also adsorbed to the NH _{4 type} resin due to the difference in selectivity, so that it is possible to continue the flow of the ammonia nitrogen-containing wastewater to the ion exchange resin tower in this state. it can. The cation exchange resin in the regenerated ion exchange resin tower connected to the most downstream side, of course, shifts from H-form to NH ₄ -form while continuing water flow.

The above description indicates that H is used as the cation exchange resin.
This is the case where a cation exchange resin of the alkali metal type such as Na type is used, which is almost the same as the case of the H type. However, as a cation exchange resin, N
When the H ₄ type is used, NH ₄ ⁺ in the water to be treated is not adsorbed by the resin, so NH ₄ ⁺ is contained in the treated water from the beginning of the passage.
₄ ⁺ is different from the above case in that it leaks.

Here, the ionic form and the regeneration of the cation exchange resin used for removing the hardness component in the present invention will be described.
First, the strongly acidic cation exchange resin will be described. When using a strongly acidic cation exchange resin in the H form, by using an acid such as hydrochloric acid as a regenerant, the hardness component adsorbed on the ion exchange resin is desorbed, and the ionic form is made into an H form, This H type is used for removing a hardness component. When using a strongly acidic cation exchange resin in NH ₄ form, use NH ₄
By using an ammonium salt such as Cl as a regenerating agent, the hardness component is eliminated and the ionic form is changed to the NH ₄ form. When the strongly acidic cation exchange resin is used in an alkali metal form, for example, in the case of the Na form, a sodium salt such as NaCl is used as a regenerant to remove the hardness component and convert the ionic form into an alkali metal form. I do.
When the strongly acidic cation exchange resin is used in the NH ₄ or Na form, an alkali such as NH ₄ OH or NaOH cannot be used as a regenerant. This is because, when alkali is passed through the cation exchange resin to which the hardness component is adsorbed, the hardness component is precipitated as a hydroxide.

Next, the weakly acidic cation exchange resin will be described. The regeneration method when the weakly acidic cation exchange resin is used in the H form is the same as that for the strongly acidic cation exchange resin described above. When using the weakly acidic cation exchange resin in NH ₄ form, first, the hardness component is desorbed by passing an acid through the resin to which the hardness component is adsorbed,
Change the ion form to H form. Next, NH ₄ was added to the H-shaped resin.
OH is passed through to form NH ₄ . In this case, the characteristics of the weakly acidic cation exchange resins, NH ₄ Cl in place of NH ₄ OH
It is not possible to make NH ₄ form by passing ammonium salt such as. In the case of a weakly acidic cation exchange resin, unlike the case of a strongly acidic cation exchange resin, even if an ammonium salt such as NH ₄ Cl is passed through a resin to which a hardness component is adsorbed, the resin is converted into an NH ₄ form. It is not possible. When the weakly acidic cation exchange resin is used in an alkali metal form, the NH
_{As in} the case of the form ₄ , first, it is regenerated with an acid to form the H form, and then an aqueous solution of an alkali metal hydroxide such as NaOH is passed through to form the Na form. Also in this case, even if a salt such as NaCl is used in place of the alkali agent such as NaOH, it is not possible to form the Na form.

As described above, in the case of a strongly acidic cation exchange resin, there is no great difference in the time required for regeneration even when used in any ion form, but in the case of a weakly acidic cation exchange resin, regeneration is easy. It is best to use the H-shape for that reason. That is, the H-form can be regenerated only by passing the acid, whereas the NH ₄ -form or the alkali metal form requires another pass-through of the drug after passing the acid. However, as described above, the weakly acidic cation exchange resin is still preferable to the strongly acidic cation exchange resin in that the ion exchange capacity is large and the regeneration with acid is easy.

In the present invention, after the hardness component in the waste water is removed by the above-mentioned ion exchange treatment, the ammonia nitrogen in the waste water is removed by an ammonia stripping method or a catalytic oxidation method. The ammonia stripping method is
Raise the pH of the water to be treated to increase the ammonium ion (NH ₄ ⁺ )
Is converted into volatile free ammonia (NH ₃ ), and then the water to be treated is brought into contact with a large amount of air to diffuse ammonia to the atmosphere to remove nitrogen. In the ammonia stripping method, the pH of the water to be treated is usually set to 11 or more, and the water to be treated is heated to a predetermined temperature.

The catalytic oxidation method is a method of oxidatively decomposing ammonia nitrogen in the water to be treated into nitrogen gas using an oxidizing agent in the presence of a catalyst (wet catalytic oxidation treatment method). In the catalytic oxidation method, generally, the water to be treated is heated to a predetermined temperature (usually 100 to 370 ° C.) in the presence of a metal catalyst, the water to be treated is pressurized to a pressure at which a liquid phase is maintained, and an oxygen-containing gas is used. (Eg, air) is supplied to the water to be treated as an oxidizing agent. As the catalyst, for example, silver, gold, platinum, cobalt,
A catalyst is used in which a catalyst component selected from nickel, palladium, rhodium, ruthenium, indium, iridium and their oxides, chlorides, sulfides and the like is appropriately supported on a carrier.

[0026]

FIG. 1 is a flow chart showing an example of a wastewater treatment apparatus used for carrying out the method of the present invention. In FIG. 1, 2 is a drainage storage tank, and 4 and 6 are a first ion exchange resin tower and a second ion exchange resin tower connected in series. Filled with exchange resin. Reference numeral 8 denotes a raw water introduction pipe provided between the drainage storage tank 2 and the first ion exchange resin tower 4. The raw water introduction pipe 8 is provided with a pump 10, a flow meter 12, and an alkali addition mechanism 14. In the figure, reference numeral 16 denotes an ion-exchange treated water discharge pipe connected to the second ion-exchange resin tower 6;
Reference numeral 8 denotes an intermediate water tank into which the ion-exchange treated water is introduced, 20 denotes an ion-exchange treated water introduction pipe connected to the intermediate water tank 18, 22
Is a pump interposed in the ion exchange treatment water introduction pipe 20;
4 is a heat exchanger connected to the ion exchange treatment water introduction pipe 20, 26 is a heater, 28 is an ammonia nitrogen removing device by an ammonia stripping method or a catalytic oxidation method, 30
Is a treated water outflow pipe, 32 is a Ca meter for measuring the calcium concentration in the treated water of the first and second ion exchange resin towers 4 and 6 respectively, 34 is a regeneration water storage tank, and 36 is a regeneration water storage tank 34
, A regeneration pipe 38, and a hydrochloric acid measuring tank 40 connected to the regeneration pipe 38 via an ejector 42. The Ca meter 32 is based on a high-frequency plasma emission method in which plasma is generated using an argon gas and emission specific to calcium is measured. Note that Ca
Instead of the meter 32, a measuring device for measuring the magnesium concentration in water or a measuring device for measuring the total hardness may be used.

The treatment of the wastewater containing ammonia nitrogen by the present apparatus is performed as follows. First, raw water (drainage containing ammonia nitrogen containing a hardness component) in the drainage storage tank 2 is successively passed through the first ion exchange resin tower 4 and the second ion exchange resin tower 6 by the operation of the pump 10 in a downward flow. Thereby, the hardness component in the raw water is removed. In the initial stage of water passage, NH ₄ ⁺ is also removed together with the hardness component. At this time, alkali is added to the water to be treated by the alkali addition mechanism 14, and the pH of the water to be treated is adjusted to about 9 to 12.
The treated water after ion exchange is stored in the intermediate water tank 18. As described above, the treated water at the beginning of the passage does not contain ammonia nitrogen, so that the treated water at this time may be discharged without being introduced into the intermediate water tank 18.

The ion-exchanged water in the intermediate water tank 18 is sequentially passed through the heat exchanger 24, the heater 26, and the ammonia nitrogen removing device 28 by the operation of the pump 22, and the ion-exchanged water is discharged in the ammonia nitrogen removing device 28. Ammonia nitrogen is removed. Ammonia nitrogen removal equipment 2
8 flows out to the treated water outflow pipe 30 and the heat exchanger 24
After the heat exchange with the ion-exchange treated water, the water is discharged or reused.

In this apparatus, the calcium concentration in the treated water of the first ion-exchange resin tower 4 and the second ion-exchange resin tower 6 is measured by the Ca meter 32, and the calcium concentration in the treated water of the first ion-exchange resin tower 4 is measured. Is performed, when the calcium concentration in the treated water reaches approximately the same value as the calcium concentration in the raw water, the cation exchange resin in the first ion exchange resin tower 4 is regenerated. The reproduction process is performed as follows.

First, the flow of water to the first ion exchange resin tower 4 is stopped, and the regeneration water (industrial water, pure water, etc.) in the regeneration water storage tank 34 is subjected to the first ion exchange in a downward flow through the extrusion pipe 36. By introducing the resin into the resin tower 4, residual water containing the hardness component in the first ion exchange resin tower 4 is extruded, and the effluent is passed through the second ion exchange resin tower 6. When the extrusion operation of the first ion exchange resin tower 4 is completed, the raw water is passed only to the second ion exchange resin tower 6. That is, the ion exchange treatment is temporarily performed in a one-column system. Thereafter, the regenerating water in the regenerating water storage tank 34 flows into the regenerating pipe 38 and the hydrochloric acid measuring tank 4
After adding hydrochloric acid from 0 to prepare a hydrochloric acid aqueous solution of a predetermined concentration, the hydrochloric acid aqueous solution is supplied in an upward flow to the first ion-exchange resin tower 4.
To be introduced. Thereby, the hardness component adsorbed on the cation exchange resin in the first ion exchange resin tower 4 is desorbed, and the ionic form of the cation exchange resin becomes the H form.
Thereafter, the flow path is switched so that the raw water flows from the second ion-exchange resin tower 6 to the first ion-exchange resin tower 4 (return to the two-column method). Note that extruding the residual water in the first ion-exchange resin tower 4 with the regeneration water before the regeneration treatment with the acid means that if the regeneration treatment with the acid is performed without extruding, the hardness component is added to the regeneration drainage. This is because ammonia nitrogen is contained, and it is necessary to remove ammonia nitrogen from the regenerated effluent.

In the present apparatus, as described above, after the second ion exchange resin tower 6 → the regenerated first ion exchange resin tower 4 is continuously supplied with water, for example, the second ion exchange resin tower 6 When the calcium concentration in the treated water reaches almost the same value as the calcium concentration in the raw water, the cation exchange resin in the second ion exchange resin tower 6 is regenerated in the same manner as described above.

[0032]

Experimental Example Two columns A and B were each filled with 100 mL of H-form weakly acidic cation exchange resin (Amberlite IRC76). Further, NH ₄ ^{+ is set} to 1700 mg / L as ammonia nitrogen (NH ₄ -N), and Ca ^{2+ is set} to 40
A simulated wastewater of pH 11 containing mg / L (asCa) was prepared,
The simulated waste water was used as raw water, and water was passed through the column A to the column B at a water passing speed of SV50.

As a result, treated water having a Ca ²⁺ concentration of 0.1 mg / L was stably obtained from the outlet of the column B. The NH ₄ ⁺ concentration in the treated water was zero at the beginning of the water flow, but was about the same as the NH ₄ ⁺ concentration in the raw water after about 10 L of water flow.
00 mg / L.

When 240 L of raw water was passed, column A
Since the Ca ²⁺ concentration in the treated water at the outlet of the column became almost the same as that of the raw water (at this time, the Ca ²⁺ concentration in the treated water of the column B was kept at 0.1 mg / L or less), The water was stopped, and the column A was backwashed and settled in a usual manner, and then 1N
440 mL of an aqueous hydrochloric acid solution was passed through the column, and then washed with pure water to regenerate the cation exchange resin to obtain a regenerated waste liquid. Analysis of the concentration of Ca ^{2+ in} the obtained reclaimed waste liquid revealed that almost 100% of Ca ²⁺ adsorbed on column A had been desorbed. In addition, NH ₄ ⁺
The concentration was as low as 10 mg / L.

After completion of the regeneration, the same simulated waste water as described above was passed through the column B to the column A (in reverse order from the previous time) at SV50. The concentration of Ca ^{2+ in} the treated water at the outlet of column A was always 0.1 mg / L or less. At the time when 200 L of the raw water was passed, the Ca ²⁺ concentration in the treated water at the outlet of the column B became almost the same as that of the raw water. At that time, the flow was stopped, and the column B was made to pass 1N hydrochloric acid as before. Regenerated with aqueous solution. After the regeneration, the raw water was passed again in the order of column A to column B to process the raw water.

From the above experiments, it can be seen that Ca in the wastewater can be almost completely removed by contacting the wastewater in which ammonia nitrogen and hardness components coexist with the cation exchange resin. Alternatively, it was confirmed that the treatment by the catalytic oxidation method can prevent the generation of scale in the treatment device and the catalyst.

[0037]

As described above, according to the method for treating nitrogen-containing wastewater according to the present invention, when treating wastewater in which ammonia nitrogen and a hardness component coexist by the ammonia stripping method or the catalytic oxidation method, It is possible to prevent the generation of scale in the apparatus and the catalyst and to continue stable processing for a long period of time, and to reduce the maintenance frequency of the processing apparatus and the catalyst to reduce the cost.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a wastewater treatment apparatus used for carrying out a method for treating nitrogen-containing wastewater according to the present invention.

[Explanation of symbols]

 2 Wastewater storage tank 4 First ion exchange resin tower 6 Second ion exchange resin tower 8 Raw water introduction pipe 14 Alkali addition mechanism 18 Intermediate water tank 24 Heat exchanger 26 Heater 28 Ammonia nitrogen removal device 32 Ca meter 34 Regeneration water storage tank 36 Extrusion Piping 38 Regeneration Piping

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D025 AA07 AA09 AB19 BA09 BA10 BA12 BB09 CA05 DA10 4D037 AA08 AA13 AB12 BA23 CA11 CA15 4D038 AA06 AA08 AB29 BA02 BA06 BB08 BB16 4D050 AA09 AA13 AB35 BB01 BC03 BD08 BD08

Claims (4)

[Claims] 1. A method for treating ammonia-nitrogen-containing wastewater by an ammonia stripping method or a catalytic oxidation method to remove ammonia-nitrogen from the wastewater, wherein the wastewater is brought into contact with a cation exchange resin to obtain a hardness component in the wastewater. A treatment by the ammonia stripping method or the catalytic oxidation method after removing the nitrogen-containing wastewater. 2. In contacting the waste water with the cation exchange resin, two or more ion exchange resin towers filled with the cation exchange resin are connected in series, and the ammonium nitrogen-containing waste water is sequentially fed to these towers. While passing water, the hardness component concentration in the treated water of the ion exchange resin tower at the most upstream side in the water flow direction is monitored, and when the hardness component concentration reaches a predetermined value, this ion exchange resin tower is regenerated and the most downstream in the water flow direction. In the next water flow process, the ion-exchange resin tower, which was located next to the ion-exchange resin tower on the most upstream side until now, is the most upstream side, and the water-flow treatment of ammonia nitrogen-containing wastewater is performed. The method for treating nitrogen-containing wastewater according to claim 1, wherein the method is performed. 3. In contacting the waste water with the cation exchange resin, two or more ion exchange resin towers filled with the cation exchange resin are connected in series, and the waste water containing ammonia nitrogen is sequentially fed to these towers. At the time when the cation exchange resin in the ion exchange resin tower at the most upstream side in the water flow direction is almost saturated with the hardness component, the ion exchange resin tower at the most upstream side in the water flow direction is regenerated and passed. It is connected to the most downstream side in the water direction, and in the next water flow process, the ion exchange resin tower that has been located next to the ion exchange resin tower on the most upstream side until now is the most upstream side, and the wastewater containing ammonia nitrogen is discharged. The method for treating nitrogen-containing wastewater according to claim 1, wherein a water-passing treatment is performed. 4. The method for treating nitrogen-containing wastewater according to claim 1, wherein a weakly acidic cation exchange resin is used as the cation exchange resin.