JPH06269776A - Device for removing ammoniacal nitrogen in water - Google Patents

Abstract

PURPOSE:To provide a device for removing ammoniacal nitrogen in water in which an ion exchange adsorption method superior in the treating speed and stability of the treating capacity is adopted, a problem of retreatment of an inorganic ion exchange body being resolved, a harmful substance is not generated and ammoniacal nitrogen is removed efficiently. CONSTITUTION:Raw water treating flow-passages consisting of a raw water supply path 2 and a treated-water discharge path 3 communicates with adsorption treating tanks 1A, 1B packed with an adsorbent consisting of zeolite, and also communicates with the recovering treatment flow passage where an adsorbent recovering treating liquid consisting of NaCl solution is fed from an adjustment tank 6 and fed back to the adjustment tank 6 through an electrolytic cell 7. In the electrolytic cell 7, the liquid is brought into contact with an anode packed with an activated coal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for removing ammoniacal nitrogen in water for removing ammoniacal nitrogen from wastewater such as domestic wastewater and industrial wastewater, and contaminated water such as rivers and lakes.

[0002]

2. Description of the Related Art In recent years, pollution of rivers, lakes and marshes or sea areas has become a problem. A large amount of ammoniacal nitrogen (hereinafter referred to as NH ₄ —N) is contained in industrial wastewater and sewage treatment plant discharge water. These releases pose a problem of harmfulness to fish and eutrophication. It is said that the cause of eutrophication is due to phosphorus and nitrogen. Conventionally, various N such as
H ₄ -N removal methods have been proposed. Air stripping method-A method in which the pH is adjusted to alkaline of 10 or more, and the gas is deaerated and released as ammonia gas. Chlorine injection method-A method of oxidizing to nitrogen by chlorine oxidizing power. Biological nitrification dechambering method-Nitrous bacteria, nitrifying bacteria produce NH ₄
^{A method in which +} is oxidized into NO ₂ ⁻ and NO ₃ ⁻ to be nitrified, and nitrogen gas is further generated by dechambering bacteria. Ion exchange adsorption method-a method of adsorbing NH ₄ -N on an inorganic ion exchanger.

[0003]

[Problems to be Solved by the Invention] Various conventional N described above
Among the H ₄ —N removal methods, the air stripping method and the chlorine injection method use a large amount of chemicals, resulting in high cost, and the chlorine injection method has a problem that residual chlorine may cause secondary pollution. Further, the biological nitrification and dechambering method has a problem that it takes a long time to process.

On the other hand, the ion-exchange adsorption method is a method that has been drawing attention in recent years and is excellent in the stability of processing speed and processing capacity. Zeolites have been attracting attention as inorganic ion exchangers. However, in this conventional ion-exchange adsorption method, the zeolite whose NH ₄ —N is saturatedly adsorbed and whose adsorption capacity is lowered must be regenerated and reused. Regeneration methods of this zeolite include a heat regeneration method and a method using various salts. In the heat regeneration method, an aqueous solution containing Na ⁺ etc. is added,
Although this method is a method of firing at about 600 degrees for 30 minutes, it has a drawback that the exchange rate and the removal rate decrease as the number of regenerations increases. The method using various salts is a method of contacting an aqueous solution of NaCl or the like and desorbing NH ₄ ⁺ by an ion exchange reaction to regenerate the zeolite. This method requires further treatment of NH ₄ ^{+ in} the regenerating solution. Is. Regeneration liquid NH
There are the above-mentioned methods (1) to ( ₄ ⁾ to remove ₄ ⁺ , but these have the above-mentioned problems.

In view of the above-mentioned conventional problems, the present invention adopts the ion exchange adsorption method, which is excellent in the stability of the processing speed and the processing capacity, solves the problem of reprocessing the inorganic ion exchanger, and eliminates the harmful substances. NH _{4 with} no generation of
It is intended to provide an apparatus for removing NH ₄ —N in water that removes —N.

[0006]

The features of the present invention for achieving the above-mentioned object are that NH ₄ such as an inorganic ion exchanger is used.
-N adsorbent treatment tank filled with an adsorbent, a raw water supply channel for supplying raw water to be treated to the adsorption treatment tank, and a treated water discharge channel for discharging treated water In the NH ₄ —N removing apparatus, a regeneration treatment liquid supply path for supplying an adsorption agent regeneration treatment liquid to the adsorption treatment tank, and a regeneration treatment liquid adjusting tank for adjusting the regeneration treatment liquid and supplying it to the regeneration treatment liquid supply path. An openable and closable regeneration treatment liquid discharge path for discharging the regeneration treatment fluid after the adsorbent regeneration treatment from the adsorption treatment tank, and the regeneration treatment liquid from the regeneration treatment solution discharge passage is regenerated by electrolytic treatment, It is provided with an electrolytic treatment tank for feeding into the liquid adjusting tank (Claim 1). In this device, using zeolite as an inorganic ion exchanger and partitioning the anode side and the cathode side of the electrolytic treatment tank with a partition plate having water permeability, and filling the activated carbon on the anode side from the partition plate, from the adsorption treatment tank It is preferable that the regenerating treatment liquid is sent to the cathode side and discharged from the anode side (claim 2).

[0007]

The NH ₄ -N in the raw water to be treated sent from the raw water supply passage to the adsorption treatment tank is adsorbed by the zeolite by passing through the zeolite tank in the adsorption treatment tank, and the treated water is discharged as treated water. It is discharged from the road.

When the zeolite has reached a saturated adsorption state, the raw water supply passage and the treated water discharge passage are closed, and then the regeneration treatment liquid is fed into the adsorption treatment tank from the regeneration treatment liquid adjusting tank. A NaCl solution of about 0.1 N is used as a regeneration treatment liquid. By this, NH adsorbed on the zeolite
₄ ⁺ is exchanged for Na ⁺ and transferred to the regeneration treatment solution. The regenerated treatment liquid after the zeolite regeneration treatment is sent to the electrolytic treatment tank and subjected to electrolytic treatment.

In the electrolytic treatment tank, chlorine gas is generated on the anode side by feeding the regeneration treatment liquid from the anode side. The chlorine gas reacts according to the following equation to form hypochlorous acid.

2Cl ⁻ → Cl ₂ ↑ + 2e ⁻ Cl ₂ + H ₂ O → HCl + HClO Hypochlorous acid decomposes as shown by the following formula and exhibits a strong oxidizing power.

2HClO → 2HCl + O ₂ ↑ At this time, NH ₄ ⁺ is oxidized to nitrogen.

By providing a partition plate of NH ₄ → 1 / 2N ₂ + 3 / 2H ₂ + H ⁺ , the anode side becomes acidic, and hypochlorous acid shows a strong oxidizing power on the acidic side (pH 3 to 6). The above reaction is effectively performed.

Further, by filling the anode side of the electrolytic treatment tank with activated carbon, the electrode area increases, the reaction increases, and the activated carbon adsorbs chlorine gas, so that the emission of chlorine gas generated is prevented.

Hydrogen gas is generated on the cathode side by a reaction represented by the following equation.

2H ₂ O + 2e ⁻ → 2OH ⁻ + H ₂ ↑ 11.2 liters of hydrogen gas is generated per Faraday of current amount. Since bubbling is alkaline (pH 12) in the vicinity of the cathode, the effect of releasing NH ₄ ⁺ as a gas is added. The electrolysis is performed at a current of about 1 A / l for a residence time of 30 minutes.

[0016]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram showing the outline of the device of the present invention. In the figure, 1A and 1B are adsorption treatment tanks having the same structure, and are filled with an adsorbent made of granular or powdery zeolite. A raw water supply passage 2 for sending raw water to be treated to the lower end side of each of the adsorption treatment tanks 1A and 1B is connected via open / close valves 2a and 2b, and a treated water discharge passage 3 for discharging the treated water to the upper end side. Are communicated with each other via the on-off valves 3a and 3b.

A regeneration treatment liquid supply passage 4 is connected to the upper ends of the adsorption treatment tanks 1A and 1B through open / close valves 4a and 4b, and a retreatment liquid discharge passage 5 is opened and closed to the lower ends thereof. The valves 5a and 5b communicate with each other.

The reprocessing liquid supply passage 4 is provided with a reprocessing liquid adjusting tank 6
And a regeneration treatment liquid consisting of a NaCl solution of about 0.1 N is supplied from the adjusting tank 6.
Further, in the adjusting tank 6, the adjusting solution made of NaCl is appropriately replenished so that the regenerated processing solution to be sent out has a constant concentration.

The regeneration treatment liquid discharge passage 5 is communicated with the electrolytic treatment tank 7. The electrolytic treatment tank 7 is an adsorption treatment tank 1A, 1B.
The regeneration treatment liquid sent from the electrolytic treatment is used again so that it can be reused. As shown in FIG. 2, a partition plate 9 having a water passage hole 8 in the lower portion is used to form an anode tank 10 and a cathode tank 11.
And the anode plate 12 is divided into the anode tank 10 and the cathode tank 11
Cathode plate 13 is inserted in each. Also partition plate 9
The anode tank 10 is filled with activated carbon 14. The anode plate 12 is made of an inert electrode material such as carbon or platinum, and when the activated carbon 14 is brought into contact with it, the activated carbon 1
The whole 4 serves as an anode. And anode tank 1
0, the regeneration treatment liquid discharge passage 5 is opened at the upper part of
A liquid feed passage 15 is opened to communicate with the upper part of the container, and the electrolytically treated regenerated treatment liquid is fed into the adjusting tank 6 through the liquid feed passage 15 for reuse.

Next, the processing steps performed by the apparatus configured as described above will be described. This device is equipped with an adsorption treatment tank 1A,
A re-adsorption treatment tank 1 includes a water treatment process in which raw water to be treated containing NH ₄ —N is fed to 1B and treated by an adsorbent for adsorption treatment, and a regeneration treatment process for regenerating a saturated adsorbent.
When the adsorbent in one of the adsorption treatment tanks 1A reaches a saturated adsorption state, the adsorption treatment is started in the other adsorption treatment tank 1B and is regenerated on one side. Start processing. This is alternately performed for continuous water treatment.

First, in the water treatment step, NH ₄ -N in the raw water to be treated is adsorbed and removed by the adsorbent by passing through the adsorption treatment tank 1A or 1B to become treated water, and the treated water is discharged through the discharge path 3. Emitted from.

The regeneration process of the adsorbent is 0.1N from the adjusting tank 6.
This is carried out by passing a regenerating treatment solution of a NaCl solution to a degree through the adsorption treatment tank 1A or 1B. As a result, NH ₄ ⁺ adsorbed on the adsorbent is exchanged for Na ⁺ and transferred to the regeneration treatment liquid. NH ₄ ^{+ of} the liquid transferred to the regeneration treatment is removed by electrolytic treatment in the electrolytic treatment tank 7. After removal, it is reused as a regeneration treatment liquid again. The NaCl consumed by the regeneration treatment liquid is replenished to the adjusting tank 6 and sent out as a regeneration treatment liquid having a constant concentration.

The electrolytic treatment of the regeneration treatment liquid is performed by the following steps. The regeneration treatment liquid that has flowed into the upper part of the anode tank 10 passes through the activated carbon 14 and from the lower part of the partition plate 9 to the cathode tank 11
Is spilled from above. At this time, chlorine gas is generated in the anode tank 10, and the chlorine gas reacts according to the following equation to become hypochlorous acid.

[0025] _{^{2Cl - → Cl 2 ↑ + 2e}} - Cl 2 + H 2 O → HCl + HClO hypochlorite decomposes as follows, showing a strong oxidizing power.

2HClO → 2HCl + O ₂ ↑ At this time, NH ₄ ⁺ is oxidized to nitrogen.

The presence of NH ₄ ⁺ → 1 / 2N ₂ + 3 / 2H ₂ + H ⁺ partition plate 9 makes the anode side acidic, and hypozinc acid has a strong oxidizing power on the acidic side (pH 3 to 6). ,
The above reaction is effectively performed. Further, since activated carbon adsorbs chlorine gas, it has an effect of preventing the release of generated chlorine gas.

In the cathode chamber 11, hydrogen gas is generated by the reaction of the following equation.

2H ₂ O + 2e ⁻ → 2OH ⁻ + H ₂ ↑ 11.2 liters of hydrogen gas is generated per Faraday of current amount. Since bubbling is alkaline (pH 12) in the vicinity of the cathode plate, an effect of adding NH ₄ ⁺ as a gas is added.

The electrolysis is performed at a current of about 1 A / liter for 30 times.
The residence time is minutes.

[0031]

As described above, in the apparatus for removing ammoniacal nitrogen in water according to the present invention, the anode side is acidic and the cathode is alkaline in the electrolytic treatment tank for the regeneration treatment of the adsorbent. Hypochlorous acid is acidic and exhibits the strongest oxidizing power.
Therefore, NH ₄ ⁺ is effectively oxidized into nitrogen gas on the anode side. On the cathode side, a part of NH ₄ ⁺ which could not be removed on the anode side is released as ammonia gas. Therefore, the air stripping method is also used, and the NH ₄ ⁺ removal effect is high.

When the anode is filled with activated carbon for use, the adsorbing capacity of the activated carbon causes less emission of chlorine gas generated, and chlorine can be effectively used. Furthermore, since the organic substances contained in the regeneration treatment liquid and the chlorine compounds generated are adsorbed on the activated carbon and oxidatively decomposed, there is an effect that no harmful substances are generated.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of the present invention.

FIG. 2 is a cross-sectional view of the electrolytic treatment tank of the above.

[Explanation of symbols]

 1A, 1B Adsorption treatment tank 2 Raw water supply passage 2a, 2b, 5a, 5b Open / close valve 3 Treated water discharge passage 3a, 3b Open / close valve 4 Regeneration treatment liquid supply passage 5 Regeneration treatment liquid discharge passage 6 Regeneration treatment liquid adjustment tank 7 Electrolysis Treatment tank 8 Water passage hole 9 Partition plate 10 Anode tank 11 Cathode tank 12 Anode plate 13 Cathode plate 14 Activated carbon 15 Liquid transfer path

Claims (2)

[Claims] 1. An adsorption treatment tank filled with an ammoniacal nitrogen adsorbent such as an inorganic ion exchanger, a raw water supply passage for supplying raw water to be treated to the adsorption treatment tank, and a treated water discharge for discharging treated water. In the apparatus for removing ammoniacal nitrogen in water, each of which is provided with a passage and a passage which can be opened and closed, a regeneration treatment liquid supply passage for supplying an adsorption agent regeneration treatment liquid to the adsorption treatment tank, and the regeneration treatment by adjusting the regeneration treatment liquid. A regeneration treatment liquid adjusting tank to be supplied to the liquid supply passage, an openable / closable regeneration treatment liquid discharge passage for discharging the regeneration treatment liquid after the adsorbent regeneration treatment from the adsorption treatment tank, and a regeneration treatment from the regeneration treatment liquid discharge passage. A device for removing ammoniacal nitrogen in water, comprising: an electrolytic treatment tank for regenerating a liquid by electrolytic treatment and sending the liquid to the regeneration treatment liquid adjusting tank. 2. An adsorption treatment tank, wherein zeolite is used as an inorganic ion exchanger, and the anode side and the cathode side of the electrolytic treatment tank are partitioned by a partition plate having water permeability, and the anode side of the partition plate is filled with activated carbon. The apparatus for removing ammoniacal nitrogen in water according to claim 1, wherein the regeneration treatment liquid from is fed to the anode side and discharged from the cathode side.