JP2014184391A - Method for regenerating amphoteric ion exchange resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable, even within a geographic region where the securing of a water supply is difficult, etc., the use of an amphoteric ion exchange resin for treating a leachate from a final disposal site, etc.SOLUTION: A solution including Caand SOis permeated through an amphoteric ion exchange resin and separated into a first solution having a low Caconcentration and a high SOconcentration and a second solution having a high Caconcentration and a low SOconcentration, and after the first solution or second solution has been permeated through a reverse osmotic membrane so as to generate pure water, the pure water is used for regenerating the amphoteric ion exchange resin. A leachate from a final disposal site may be provided as the solution including Caand SO, whereas the amphoteric ion exchange resin is positioned on the upstream side of a chemical liquid reaction tank for adding chemicals so as to remove heavy metals from the leachate at the final disposal site, whereas the pure water generated by permeating, through the reverse osmotic membrane, the second solution generated from the amphoteric ion exchange resin can be used for regenerating the amphoteric ion exchange resin.

Description

  The present invention relates to a method for regenerating an amphoteric ion exchange resin, and more particularly to a method for regenerating an amphoteric ion exchange resin used to prevent the generation of scale caused by calcium in a final disposal site.

  Waste disposal sites and other final disposal sites are facilities for disposing of wastes that are difficult to recycle. However, in view of the danger of exhaustion, effective use of wastes that have been treated at the final disposal site so far Is promoted.

  Incineration ash generated when municipal waste is incinerated has recently been recycled as a raw material for cement in view of the danger of depleting the final disposal site. Of municipal incineration ash, fly ash that is carried with gas and collected by the dust collector contains 10 to 20% of chlorine, so water-soluble chlorine contained in fly ash using water washing and desalination equipment After removing the compound with water, it is used as a cement raw material (see, for example, Patent Document 1).

However, in the final disposal site, calcium sulfate (Ca ²⁺ ) contained in the leachate and sulfate ion (SO ₄ ²⁻ ) produces calcium sulfate (CaSO ₄ ), which is used as a scale in filtration equipment and subsequent wastewater treatment processes. As a result, it has adhered to the apparatus and the stable operation is hindered.

  Therefore, for example, as shown in FIG. 3, in the final disposal site 30, in the chemical reaction tank 32 in order to remove calcium and harmful heavy metals that cause scale generation from the leachate W stored in the adjustment tank 31. A chemical such as sodium carbonate is added, and these are precipitated and removed by the filtration device 33, and then desalted by the electrodialysis device 36 through the COD treatment device 34 and the suspended substance removal device 35. As a result, the desalted water D having a water amount of 0.9Q is discharged with respect to the water amount 1Q of the leachate W, and the concentrated water C having a water amount of 0.1Q is evaporated to recover the salt.

  However, in the above method, since a large amount of sodium carbonate needs to be added, there is a problem that the drug cost increases and the operation cost increases.

Therefore, in Patent Document 2, the applicant of the present invention provides an amphoteric ion exchange resin 41 on the downstream side of the suspended substance removing device 35 as shown in FIG. 4, and uses the leachate W in the final disposal site 30 as Ca ^2+. concentration is low, Cl ^- concentration is higher the first solution L1, high Ca ²⁺ concentration, Cl ^- concentration were separated low and the second solution L2, supplies the first solution L1 to the electrodialysis apparatus 36 In this way, we proposed a method for treating leachate from the final disposal site without the need to add a large amount of sodium carbonate. In addition, in the electrodialysis apparatus 36, the desalted water D of 1.1 to 1.4Q of water and the concentrated water C of 0.1Q of water are obtained with respect to 1Q of the leachate W, and the desalted water D is discharged. The concentrated water C is evaporated to recover the salt. Moreover, 3Q industrial water IW is used for the regeneration of the amphoteric ion exchange resin 41 with respect to the amount 1Q of the leachate W.

Japanese Patent Laid-Open No. 11-100343 Japanese Patent No. 4766719

  The treatment method of the leachate in the final disposal site described in Patent Document 2 is preferable because it does not require the addition of sodium carbonate, and can reduce the cost of the drug. However, as described above, the amphoteric ion exchange resin 41 is used. When regenerating, industrial water IW that is three times as much as leachate W is required, so there is a problem that it cannot be used in areas where it is difficult to secure the amount of water.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and uses an amphoteric ion exchange resin for the treatment of leachate in the final disposal site even in areas where it is difficult to secure the amount of water. The purpose is to make it possible.

In order to achieve the above object, the present invention is a method for regenerating an amphoteric ion exchange resin, wherein a solution containing Ca ²⁺ and SO ₄ ²⁻ is passed through the amphoteric ion exchange resin to reduce the Ca ²⁺ concentration, SO ₄ ^2-high concentration first solution, high Ca ²⁺ concentration, and separated into a low SO ₄ ^2- concentration second solution, the first solution or second solution a reverse osmosis membrane And purified water is used to regenerate the amphoteric ion exchange resin.

According to the present invention, a solution containing Ca ²⁺ and SO ₄ ^2-a, the first solution and the reverse osmosis membrane to separate into a second solution Ca ²⁺ and SO ₄ ^2-and does not coexist Since it is allowed to pass through, no gypsum scale is generated in the reverse osmosis membrane. Therefore, the reverse osmosis membrane can be used continuously, and the industry used to regenerate the amphoteric ion exchange resin by generating pure water from the solution generated with the amphoteric ion exchange resin and using it for the regeneration of the amphoteric ion exchange resin. The amount of water used can be reduced.

In the above ampholytic ion exchange resin regeneration method, the solution containing Ca ²⁺ and SO ₄ ^2- can be used as leachate at the final disposal site, and even in areas where it is difficult to secure the amount of water, final disposal It becomes possible to use an amphoteric ion exchange resin for the treatment of the field leachate.

  In addition, the amphoteric ion exchange resin is disposed on the upstream side of the chemical reaction tank to which a chemical is added to remove heavy metals from the leachate at the final disposal site, and the second solution generated by the amphoteric ion exchange resin is disposed. Pure water generated by passing through the reverse osmosis membrane can be used to regenerate the amphoteric ion exchange resin. As a result, even if the leachate from the final disposal site has a high calcium content, the leachate from the final disposal site can be removed simply by treating the calcium remaining in the first solution that has passed through the amphoteric ion exchange resin with sodium carbonate or the like. Can be processed.

It is the schematic for demonstrating an example of the processing method of the leachate of the final disposal site to which the regeneration method of the amphoteric ion exchange resin which concerns on this invention is applied. It is a graph which shows the operation example of amphoteric ion exchange resin shown in FIG. It is the schematic for demonstrating an example of the processing method of the leachate of the conventional final disposal site. It is the schematic for demonstrating the other example of the processing method of the leachate of the conventional final disposal site.

  Next, modes for carrying out the present invention will be described with reference to the drawings. In the following description, an example will be described in which amphoteric ion exchange resin is used for the treatment of leachate in the final disposal site and the amphoteric ion exchange resin is regenerated in the course of this treatment.

FIG. 1 shows an example of a leachate treatment system (hereinafter simply referred to as “treatment system”) at a final disposal site to which the method for regenerating amphoteric ion exchange resins according to the present invention is applied. an adjustment tank 3 for storing the leachate W from field 2, the leachate W and Ca ²⁺ concentration is low SO ₄ ^2-high concentration first solution L1 from the adjustment tank 3, high Ca ²⁺ concentration An amphoteric ion exchange resin 4 that separates into a second solution L2 having a low SO ₄ ²⁻ concentration, a reverse osmosis membrane 5 that produces pure water P from the second solution L2 from the amphoteric ion exchange resin 4, and amphoteric ions Calcium / heavy metal removal device 6 that removes calcium ions and heavy metal ions remaining in first solution L1 from exchange resin 4, thickener 7 that precipitates and removes calcium and heavy metals, COD treatment device 8, and suspended matter removal Consists of device 9 .

  The amphoteric ion exchange resin 4 is provided for separating calcium from the leachate W discharged from the adjustment tank 3. The amphoteric ion exchange resin 4 has a function of allowing ion exchange with both the cation and the anion by making the base material cross-linked polystyrene or the like and having a quaternary ammonium group and a carboxylic acid group in the same functional group chain. Resin. For example, amphoteric ion exchange resin, Diaion (registered trademark), AMP03 manufactured by Mitsubishi Chemical Corporation can be used. The amphoteric ion exchange resin 4 can separate the electrolyte and the non-electrolyte in the aqueous solution, and can also separate the electrolytes from each other.

  The reverse osmosis membrane (RO membrane) 5 is a membrane having the property of allowing water to pass through but not allowing impurities other than water, such as ions and salts, to be passed, and is practically used for desalination of seawater. The reverse osmosis membrane 5 separates the second solution L2 into pure water P and concentrated water C.

  Next, the operation of the processing system 1 having the above configuration will be described with reference to FIGS.

  The leachate W from the final disposal site 2 is stored in the adjustment tank 3 and then introduced into the amphoteric ion exchange resin 4 to perform calcium separation operation. That is, the leachate W is separated into the first solution L1 and the second solution L2.

FIG. 2 is a graph showing an operation example of the amphoteric ion exchange resin 4 shown in FIG. In the figure, the above-mentioned Diaion AMP03 manufactured by Mitsubishi Chemical Corporation is used as the amphoteric ion exchange resin 4, and the pure water P and the industrial water IW from the reverse osmosis membrane 5 are used as the leachate W in the final disposal site 2 and the reclaimed water. The concentration of each component of the treated water in the case where is introduced alternately into the amphoteric ion exchange resin 4 is shown. This graph, the amphoteric ion exchange resin 4, leachate W is Ca ²⁺ concentration as low as SO ₄ ^2- high concentration first solution L1, Ca ²⁺ concentration is high SO ₄ low ² concentration second It turns out that it isolate | separates into the solution L2.

Next, the 2nd solution L2 is isolate | separated into the pure water P and the concentrated water C with the reverse osmosis membrane 5, the pure water P is used for reproduction | regeneration of the amphoteric ion exchange resin 4, and the concentrated water C is discharged. The reverse osmosis membrane 5 could not be operated when a scale of gypsum (CaSO ₄ .2H ₂ O) was adhered, but as described above, the amphoteric ion exchange resin 4 was used to cause the first solution L1 and the second solution to move. Since it is separated into L2, SO ₄ ²⁻ and Ca ²⁺ do not coexist in each of the first solution L1 and the second solution L2, and there is no possibility that the gypsum scale adheres to the reverse osmosis membrane 5. Therefore, the stable operation of the reverse osmosis membrane 5 can be continued.

In addition to gypsum (CaSO ₄ .2H ₂ O), calcium carbonate (CaCO ₃ ) can also be a calcium scale, but since calcium carbonate is easily soluble in acid, it can be washed with an acid.

  On the other hand, the first solution L1 discharged from the amphoteric ion exchange resin 4 was passed through a calcium / heavy metal removing device 6, a thickener 7 for precipitating and removing calcium and heavy metals, a COD treatment device 8, and a suspended substance removing device 9. After release. If a little calcium remains in the first solution L1, this calcium may be treated with sodium carbonate or the like. The calcium / heavy metal removed water L3 from which calcium and heavy metals have been removed by the thickener 7 The organic substance and the reducing inorganic substance are oxidized, and the suspended substance is removed by the suspended substance removing device 9.

  As described above, in the present embodiment, by using the reverse osmosis membrane 5, the amphoteric ion exchange resin 4 can be regenerated with a small amount of industrial water IW.

  In the above embodiment, pure water P is generated from the second solution L2 by the reverse osmosis membrane 5, but pure water P can also be generated from the first solution L1, and these are separately separated from the reverse osmosis membrane 5. , The pure water P can be generated from both and used for the regeneration of the amphoteric ion exchange resin 4.

  Moreover, although the case where the amphoteric ion exchange resin 4 was used for the treatment of the leachate W at the final disposal site 2 was described, the present invention can be applied to drainage other than the leachate W at the final disposal site 2.

1 treatment system 2 final disposal site 3 adjustment tank 4 amphoteric ion exchange resin 5 reverse osmosis membrane 6 calcium / heavy metal removal device 7 thickener 8 COD treatment device 9 suspended matter removal device C concentrated water IW industrial water L1 first solution L2 first Solution L3 2 Calcium / heavy metal removed water P Pure water W Leached water

Claims (3)

The solution containing Ca ²⁺ and SO ₄ ^2-and was passed through an amphoteric ion-exchange resin Ca ²⁺ concentration is low, the first and the solution SO ₄ ^{2-concentration} is high, high Ca ²⁺ concentration, SO ₄ ^2- Separating into a second solution having a low concentration, and passing the first solution or the second solution through a reverse osmosis membrane to produce pure water, which is used for regeneration of the amphoteric ion exchange resin. A method for regenerating an amphoteric ion-exchange resin, which is characterized by using. The method for regenerating an amphoteric ion exchange resin according to claim 1, wherein the solution containing Ca ²⁺ and SO ₄ ^2- is leachate from a final disposal site.   The amphoteric ion exchange resin is disposed on the upstream side of a chemical reaction tank to which chemicals are added in order to remove heavy metals from leachate at the final disposal site, and the second solution generated by the amphoteric ion exchange resin is reversely mixed with the reverse solution. The method for regenerating an amphoteric ion exchange resin according to claim 2, wherein pure water produced by passing through the osmotic membrane is used for regeneration of the amphoteric ion exchange resin.

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