JPS5944895B2 - How to regenerate adsorbent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating an adsorbent, and particularly to a method for regenerating an adsorbent made of sulfate radical-containing aluminum hydroxide or zeolite.

Removal of nitrogen or phosphorus, which are eutrophic substances in water bodies, is extremely important, and many removal methods have been developed.

Activated alumina, calcium phosphate minerals, or aluminum hydroxide containing sulfate groups are known as adsorbents for phosphate ions contained in waste water, sewage, etc.

The present inventors focused on the fact that aluminum hydroxide containing sulfate groups has a high ability to adsorb phosphate ions, and as a result of repeated studies on how to regenerate them, they found that they can be regenerated with an aqueous sodium sulfate solution with a pH of 3 to 5. The present invention was completed based on this finding.

That is, the present invention relates to a method for regenerating an adsorbent made of sulfate group-containing aluminum hydroxide that has adsorbed phosphate ions using an aqueous solution of sodium sulfate having a pH of 3 to 5.

The method for producing the sulfate group-containing aluminum hydroxide of the present invention involves preparing an aqueous aluminum sulfate solution or other water-soluble sulfates (e.g., sodium sulfate, magnesium sulfate) and a water-soluble aluminum salt (e.g., aluminum chloride, nitric acid). A method of precipitating aluminum hydroxide containing sulfate groups through a neutralization reaction by adding a hydroxide, carbonate, bicarbonate, aluminate, etc. of a near-alkali metal to a mixed aqueous solution of aluminum (aluminum, organic acid aluminum), or
A method of precipitating aluminum hydroxide containing sulfate groups by adding urea to the above solution and thermally decomposing the urea is known.Also, the adsorbent of the present invention can be used alone, but the adsorbent of the present invention Zeolite in solution during production,
The adsorbent of the present invention may be deposited and coated on a dispersed carrier such as perlite or plastic spheres.

The present invention is not limited to those produced by these methods.

As mentioned above, the present invention uses a sulfuric acid aqueous solution of pH 3 to 5 to regenerate an adsorbent made of sulfate group-containing aluminum hydroxide used to remove phosphate ions from wastewater, for example. However, to adjust this pH, an appropriate acid such as sulfuric acid, hydrochloric acid, nitric acid, etc. is used. However, when the pH of the aqueous solution is below 3, the aluminum content in the adsorbent is eluted; If this happens, the regeneration effect will be significantly reduced.

Therefore, the concentration of the sodium sulfate aqueous solution is Na2S
A concentration of 1 to 10% by weight as O4 is preferable; if it is less than 1%, the regeneration effect is small, and even if it exceeds 10% by weight, a regeneration effect proportional to the concentration cannot be expected, which is not economical.

As an embodiment of the regeneration method, for example, the aqueous solution of the present invention may be passed through a packed column filled with an adsorbent, or the aqueous solution of the present invention may be added to the aqueous solution of the present invention and then slowly stirred and then filtered and washed with water.

In short, the adsorbent can be regenerated by bringing the aqueous solution of the present invention into contact with the adsorbent by any known method.

11.0.1NH2S04 or 0.1NH2S04 is used to regenerate the sulfate group-containing aluminum hydroxide adsorbent of the present invention. When INNaOH is used, the adsorbent dissolves, making it unsuitable as a regeneration solution, and NaCl has no regeneration effect at all.

In general, sewage and industrial wastewater often contain phosphate ions and ammonium ions, and in order to remove both of these ions, aluminum hydroxide and zeolite containing Bicyl radical can be used separately or in a mixture. All you have to do is fill the tower and pass water through it.

If the regeneration solution according to the present invention is used as a method for regenerating the adsorbent in this case, there is an advantage that the adsorbent can be regenerated at once.

Now, as the regeneration solution of the present invention is used, its concentration gradually decreases, and the concentrations of phosphate ions, ammonium ions, etc. increase, so that the regeneration function gradually decreases.

In such a case, if sodium hydroxide and sodium carbonate are added to the used regeneration solution to make it alkaline, NH4 will be volatilized as NH3, and PO4 will be precipitated and removed with calcium compounds, etc., and then the pH will be adjusted to 3 with H2SO4. The regeneration solution can be renewed by adjusting it to ~5.

On the other hand, even if an adsorbent is regenerated, its adsorption performance gradually deteriorates, so it should be updated as necessary, but this can be effectively utilized in the present invention.

That is, the adsorbent of the present invention is prepared by adding it to a NaOH solution and stirring it to elute the aluminum component, and then adding it to a NaOH solution and stirring it to elute the aluminum content.
After separating the components, an adsorbent can be produced by adding sulfuric acid or a soluble sulfate to this solution to precipitate aluminum hydroxide containing sulfate groups.

As described above, according to the method of the present invention, phosphate ions can be easily regenerated, and used regenerating solutions can be renewed in a simple manner.The method of the present invention has many advantages. .

Examples of the present invention will be described below.

Example 1 A 10% sodium carbonate aqueous solution was added to 500g of aluminum sulfate aqueous solution (A12022) with stirring to pH 5.8.
A precipitate was produced by dropwise reaction until the mixture was filtered, washed with water, and the washed precipitate was air-dried to give a composition of A120334.8%,
, 17.6% of aluminum hydroxide containing sulfate radicals was obtained.

1g of this sulfate radical-containing aluminum hydroxide is 500rfL
l ammonium phosphate aqueous solution (Po, 50■/l)
After stirring slowly for 1 hour and filtering, the PO4 concentration in the p solution was measured and found to be 3.71 ng/A.

This sulfate group-containing aluminum hydroxide that has adsorbed phosphate ions is added to 200ml of 0.IN sodium sulfate aqueous solution adjusted to pH 4.3 with HC7, stirred slowly for 30 minutes, filtered and washed with water, and then mixed with 500rrLl of ammonium phosphate again. The result of measuring the residual P04 in the filtered water by adding it to the solution (50■/1PO4) and adsorbing it was 10.2■/l.
Met.

On the other hand, as a comparative example, 0. As a result of repeated adsorption tests in the same manner without treatment with IN sulfuric acid I-IJ aqueous solution,
The PO4 in the first mud solution was 3.7 .mu./l, and the PO4 in the p solution at the time of reuse was 45.8 .mu./l.

Example 2 Na-type zeolite powder 5 (Bi'
A12032 aluminum sulfate aqueous solution 125
Composite adsorbent in which zeolite is coated with aluminum hydroxide containing sulfate radicals by dispersing it in rILl and dropping an aqueous solution of sodium carbonate at a concentration of 20 with stirring until the pH reaches 6.3, filtering and drying at 105°C. was manufactured.

1g of this adsorbent, NH423, Omty/l 1P0
．． Added to 500 m7 of sample water containing 9.7 mfil/l,
After adsorption under the conditions of 30 rpm 120° CI time,
When filtered and analyzed for NH, and PO4 in the slurry, they were 4.0~/l and 0.06~/l, respectively.

The adsorbent on the filter paper was treated with O, i N Na 2 at pH 3.7.
The beaker was rinsed with SO regeneration solution, the same solution was added to make a total volume of 200 rrLl, and the mixture was regenerated at 30 rpm at 20° C. for 0.5 hour.

After regeneration, filter again, wash with water, rinse it into a beaker with the above sample water, and add sample water to make a total volume of 500 rnl.
The adsorption test for the first regeneration was conducted in the same manner and the p-peroxide was analyzed and the result was NH44.2/l.

PO40.17~/l.

The regeneration was repeated in the same way, and the concentrations of NH4 and PO in the filtered water after the second regeneration adsorption test were 5.0 to 1/1, respectively.
1. L was 87my/12.

On the other hand, as a result of repeated adsorption tests under the same conditions without regeneration, the NH in the first filtered water was 4.0~
/l, PO4 is 0.06~/11 Second filtered water (7) NH4 is 8.21n9/11 PO4 is 1.72m
9/13. NH4 in the third filtered water is 16.2 mg,
#1 PO4 huff was 6 mg/l.

Example 3 Sulfuric aluminum aqueous solution (A12031.5%) 5Kg
After dissolving 200 g of urea in the solution, it was heated to the boiling point and stirred for 5 hours. The resulting precipitate was filtered, washed with water, and dried to obtain sulfate-containing aluminum hydroxide (
AA20340.3, 5O418, 3) were obtained.

In addition to 500 d of sample water (Po, 52.4~#) obtained by dissolving 1 g of each of these adsorbents in KH2PO4; Then, PO in the swamp water was analyzed.

The adsorbent on the paper is 5% Na adjusted to a specified pH with sulfuric acid.
Rinse into a beaker with 2SO4 aqueous solution, total volume 200ml
After regenerating at 20°C and 0.5 hr 30 vpm, the adsorbent on the Oki paper was washed with water and the above PO4
Rinse into a beaker with containing sample water, add sample water and wait 500 m.
1, the first regeneration adsorption test was conducted.

The regeneration-adsorption process was repeated in the same manner, and the influence of the pH of the regeneration Na2SO4 liquid on the regeneration effect was investigated. The results are shown in Table 3.

Example 4 A glass cylinder with an inner diameter of 25 mm and a height of 300 mm was filled with 50 g of 8 to 20 meshes of Na-type zeolite, and 5 g of the sulfate group-containing aluminum hydroxide obtained in Example 3 was filled above the cylinder.

Activated sludge treated sewage water (N
H48~12m9/11 average 10.37V/71P0.
4.1~6.7m9/! 3 average 5.2~. #) wosv2
．． 5, the NH, PO, of the treated water was measured at regular intervals, and the amount of adsorption per gram of adsorbent was measured when the NH4 concentration of the treated water reached 2.0 ta/7. NH4
It was 4,45In9.

Additionally, the PO4 in the treated water at this point was 0.45m9/
It was A.

Next, a 5% Na 2 S 04 aqueous solution 11 adjusted to pH 3.5 was passed through it at SV 2.5, washed with tap water, and the same sample water was passed through it again to adsorb it, so that the NH concentration of the treated water was 2. .0
The amount of adsorption per 1 g of adsorbent was measured at the time when the amount reached ~/l, and the result was 4.52 .

Also, the PO4 concentration in the treated water at this point was 1.21n9
/l.

Claims (1)

[Claims] A method of regenerating an adsorbent made of aluminum hydroxide containing a sulfate group that has adsorbed phosphate ions using an aqueous solution of sulfuric acid and sodium sulfate having a pH of 3 to 5.