JPS6059038B2 - Ammonium ion removal equipment in water - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an apparatus for removing ammonium ions in water, and more specifically, an apparatus for removing ammonium ions in liquids such as tap water, sewage, and wastewater using an adsorption device having a cation exchange function. This invention relates to a device for removing ammonium ions in water, which can remove ammonium ions from water using an adsorbent and simultaneously regenerate the adsorbent within the same device.

[Background of the invention]

Ammonium ions (hereinafter referred to as JNH) in water such as sewage and wastewater
(sometimes written as 4+)), like phosphorus, makes water eutrophic and significantly reduces water quality.

Therefore, in advanced treatment of sewage, wastewater, etc., removal treatment is necessary. Conventional ammonium ion removal methods include (1) discontinuous treatment with sodium hypochlorite (or chlorine), (2) ammonia stripping, (
There are 3) ion exchange methods, (4) zeolite adsorption methods, and (5) biochemical methods, but these methods have various drawbacks as described below.

In other words, the treatment method using sodium hypochlorite (or chlorine) is desirable because it decomposes NH4+ into nitrogen gas, but if the chlorine additive is used in excess, it generates chloramine-based malodorous components. Also, if the amount added is insufficient,
Since the decomposition reaction of NH4+ does not proceed, its adjustment is troublesome.

In the stripping method, which involves adding an alkaline agent and blowing air into the treatment, there is a problem that the ammonia stripping efficiency is poor and that the stripped ammonia gas is released into the atmosphere, causing secondary pollution.
In the ion exchange method and the zeolite adsorption method, it is difficult to regenerate the adsorbent, and treatment of the regenerated liquid becomes a problem.

In other words, playback can be performed in a short time. Therefore, a separate adsorption tower must be prepared to perform regeneration and adsorption alternately. In addition, these adsorbents can be regenerated by using chemicals containing sodium ions, etc., but since the regenerating solution contains concentrated ammonium ions,
Secondary treatment is required. Also, zeolite is 300-7
Although it can be regenerated by heating to 00° C., post-treatment is still required since the ammonium component becomes NH3 or NOx. Furthermore, there are various drawbacks such as the inability to perform adsorption and desorption at the same time, making it difficult to carry out continuous NH4+ treatment. The biochemical method uses nitrifying bacteria to nitrify NH4+ to NOx, and denitrifying bacteria to decompose it into nitrogen gas. However, it has the disadvantage that a large reaction layer is required due to the slow reaction rate. [Object of the Invention] An object of the present invention is to provide an apparatus for removing ammonium ions in water suitable for quickly and completely removing NH, + from sewage, wastewater, etc.

[Summary of the Invention] In order to achieve the above object, the first aspect of the present invention is that an adsorbent having a cation exchange function is filled in a space sandwiched between a cation exchange membrane and an anion exchange membrane. an adsorption tower, each electrode chamber having negative and positive electrodes provided outside the adsorption tower corresponding to a cation exchange membrane and an anion exchange membrane and to which a voltage is applied; It is characterized by comprising means for circulating a liquid, means for distributing an alkali metal chloride solution into the electrode chamber, and a reaction tower for mixing and reacting the gas and liquid exiting the electrode chamber. be.

A second aspect of the present invention is that the above-described invention is further provided with a circulation path for returning the reaction liquid obtained in the reaction tower to the original electrode chamber.

In the first invention of the present application, ammonium ions in water are adsorbed on an adsorbent having a cation exchange function, and at the same time,
The adsorbent that has adsorbed this NH4+ ion can be regenerated within the same device. Furthermore, the desorbed NH4+ ions are converted into harmless nitrogen gas within the reaction tower. Further, in the second invention of the present application, since the reaction liquid in the reaction tower is circulated to the electrode chamber, the treatment of NH4+ can be closed.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in more detail with reference to embodiments shown in the drawings.

The drawing is a schematic flow sheet showing one embodiment of the device of the present invention. This device uses an adsorbent having a cation exchange function, typically zeolite or/and a cation exchange resin (hereinafter referred to as an adsorbent), in a space sandwiched between an anion exchange membrane 2 and a cation exchange membrane 3. an adsorption tower 4 filled with adsorption towers (sometimes collectively referred to as It mainly consists of electrode chambers 5A and 6A having . Piping 8 for introducing alkali metal chloride solution
A is connected to discharge chambers 5A and 6A, respectively. In this embodiment, the alkali metal chloride solution is electrolytically treated and then flows from the upper part of the electrode chamber through the pipe 8B and into the reaction tube 9, where the alkali metal chloride is regenerated by the reaction described below. It is configured to be returned to the tank of the chloride solution 8 and recycled. The reaction tower 9 is provided with a gas outlet 10 for the generated nitrogen gas, and the circulation system is provided with means for supplying a pH adjustment liquid 11 for adjusting the pH of the circulating liquid after the reaction. Note that 7 indicates a power source. In the above system, a liquid to be treated 1 containing MV is treated by an adsorbent in an adsorption tower 4 having an anion exchange membrane 2 and a cation exchange membrane 3, and is discharged or reused as clean water from a pipe 1B. .

The reaction formula (1) at this time is shown. In the formula, Z means zeolite and R means an ion exchange membrane agent matrix.

Generally, the amount of wastewater to be treated Q(1) is the amount of adsorbent W(g)
, NH4+ concentration C (Ppm), and adsorption capacity q (M9-NH4+/V) of MV of the adsorbent according to the following equation (2).

Therefore, in conventional adsorption operations, the adsorption operation had to be temporarily stopped after the Q(g) treatment, and the adsorbent had to be regenerated by some method.

(Actually, the adsorption operation must be stopped when Q becomes smaller (breakthrough point).) In the present invention, a DC voltage is applied to electrodes 5 and 6 outside the adsorption tower, and
A contains sodium chloride (NaCl), potassium chloride (KC
A circulating liquid 8 is supplied with an alkali metal chloride solution such as chloride.

At this time, the anion exchange membrane 2 side is the anode, and the cation exchange membrane 3 side is the anode.
The voltage is applied so that the side becomes a cathode. This device therefore forms an electrodialysis cell, and the interior of the adsorption tower 4 becomes a desalination chamber (or dilution chamber) in the sense of electrodialysis technology. Therefore, when NH4+ in the water to be treated 1 flows into the adsorption tower 4, most of the NH,+ is adsorbed by the ion exchange resin or zeolite. However, the adsorbed MVs are desorbed from the adsorbent under the influence of the electric field, the adsorbent is regenerated, and NH4+ passes through the cation exchange membrane 3 and reaches the cathode 6. reach. That is, although the water to be treated 1 is purified by applying electricity from the power source 7, the adsorbent in the adsorption tower 4 is not penetrated. Therefore, adsorption and desorption can be performed continuously in the same device without stopping the adsorption operation for regeneration. At this time, chlorine ions are oxidized on the surface of the anode 5 according to the following equation (3), and chlorine gas is generated. On the other hand, on the surface of cathode 6 (4)
0H- ions are generated as shown in the formula. Cl2 in the electrode chamber 5A and OH- in the electrode chamber 6A are sent to the reaction tube 9 together with the alkali metal chloride solution. At the same time, the aforementioned Nl
I4+ is also sent from the electrode chamber 6A to the reaction tube 9, where NH
4+, Cl2, and OH- are mixed and react as shown in the following equations (5) and (6), and NH4+ becomes N2 gas and becomes harmless. The generated N2 gas is removed from gas outlet 1.
0 is released outside the system. Considering the above mass balance, only N2 gas is released from the system, and the rest remains in the liquid with the generation of protons (H).
In the end, it is arranged as shown in the following equation (7), and the pH adjustment liquid 11 is added to the liquid as necessary, so that it can be reused as an alkali metal chloride solution (circulating liquid 8).

Examples and comparative examples of the present invention are shown below.

EXAMPLE 1 AND COMPARATIVE EXAMPLE A 50CT high vessel filled with natural zeolite was filled with waste liquid containing 50 ppm of NH4+! 1. Nlil+ was removed by passing through an adsorption tower with a cross-sectional area of 100 cIt (1 x 100) at SV=group-1 and liquid volume of 251/h (Comparative Example 1).

In this method, when one bottle of wastewater is treated, the treated water contains NH, +
was detected, requiring a 4-hour run to regenerate the adsorbent. Next, using natural zeolite as an adsorbent and an aqueous sodium chloride solution as an alkali metal chloride solution, treatment was carried out using the apparatus of the present invention shown in the drawings.

The conditions such as adsorption tower size, wastewater NH4+ concentration, and SV are the same as above. A common commercial product was used as the ion exchange membrane, and a 2% NaCl solution was used as the circulating fluid, which was circulated at a flow rate of 5 e/h. The electrodes are platinum plates (10 x 50
cIt), and 27cm (DC constant voltage) was applied. When the adsorption tower was filled with distilled water, no current flowed, but when a waste liquid containing 50 ppm of NH4+ was supplied into the adsorption tower, a current of 1 to 100% flowed. At this time, from the anode surface, C
Generation of l2 gas was observed, and bubbles were also generated within the reaction tower 9, and this gas was confirmed to be N2 gas.
As the operation continued, the pH inside the reaction column decreased to 1 (the initial pH of the NaCl solution was 6), so a PH adjustment solution consisting of a 1% NaOH solution was added to bring the pH to 6 and the reactor was recycled. After 20 hours of continuous operation, no NHL+ was detected in the treated water.

Example 2 Wastewater was treated under the same conditions as Example 1 except that the SV of the adsorption tower was 1011-1. From the treated water;
0.2 ppm (7) NH4+ was detected, which decreased to 10 ppm after 1 hour.

Therefore, when the wastewater supply was lowered to SV5h-1, no MV was detected in the treated water after one sieve. In the case of this example, the adsorption zone became longer in SVlOh-1, and it is thought that NH,+ leaked out. Furthermore, this experiment revealed that even if the adsorbent breaks through, the adsorbent can be regenerated by lowering the SV. Example 3 Even when a commercially available cation exchange resin was used in place of the natural zeolite in Example 1, almost the same results were obtained.

〔Effect of the invention〕

As described above, according to the present invention, since adsorption and regeneration can be performed simultaneously, there is no need to temporarily stop the operation and perform the regeneration operation as in the conventional case, and the liquid to be treated can be processed continuously and quickly. Can be done.

Therefore, there is no need to install adsorption towers in parallel for regeneration as in the conventional case, and the device can be downsized. In addition, NH4+ generated by the regeneration operation reacts with the electrolyzed product within the device and can be converted into harmless nitrogen gas, so no secondary pollution occurs, and the treated liquid can be recycled. Excellent effects such as the ability to close the entire device system can be obtained.

[Brief explanation of the drawing]

The drawing is a flowchart showing an apparatus system for explaining an embodiment of the present invention. 1... Water to be treated, 2... Anion exchange membrane, 3... Cation exchange membrane, 4... Adsorption tower, 5, 6... ... Electrode, 8 ... Circulating fluid (
alkali metal chloride solution), 9... reaction tube, 1
1... Add liquid to p.

Claims (1)

[Scope of Claims] 1. An adsorption tower in which a space sandwiched between a cation exchange membrane and an anion exchange membrane is filled with an adsorbent having a cation exchange function; Each electrode chamber has negative and positive electrodes provided corresponding to the exchange membrane and anion exchange membrane, respectively, to which a voltage is applied; means for circulating the liquid to be treated to the adsorption tower; An apparatus for removing ammonium ions in water, comprising means for circulating a metal chloride solution, and a reaction tower for mixing and reacting gas and liquid exiting the electrode chamber. 2. An apparatus for removing ammonium ions in water according to claim 1, wherein the adsorbent is a zeolite or/and a cation exchange resin. 3. The device for removing ammonium ions in water according to claim 1 or 2, wherein the alkali metal chloride is sodium chloride or potassium chloride. 4. An adsorption tower filled with an adsorbent having a cation exchange function in a space sandwiched between a cation exchange membrane and an anion exchange membrane, and a cation exchange membrane and an anion exchange membrane outside the adsorption tower. each electrode chamber having negative and positive electrodes provided correspondingly to each other and to which a voltage is applied; a means for circulating the liquid to be treated to the adsorption tower; and a means for circulating the alkali metal chloride solution to the electrode chamber. The method is characterized by comprising means, a reaction column for mixing and reacting the gas and liquid exiting both electrode chambers, and a circulation path for returning the reaction liquid obtained in the reaction column to the original electrode chamber. Equipment for removing ammonium ions in water. 5. An apparatus for removing ammonium ions in water according to claim 4, wherein the adsorbent is zeolite or/and a cation exchange resin. 6. The device for removing ammonium ions in water according to claim 4 or 5, characterized in that a pH adjusting means is provided in the circulation path of the reaction liquid. 7. The device for removing ammonium ions in water according to any one of claims 4 to 6, wherein the alkali metal salt compound is sodium chloride or potassium chloride.