JP2705813B2 - Activated carbon treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to water containing free chlorine by filtering groundwater or tap water with an activated carbon filter and treating the filtered water with an electrolytic chlorine generator. The present invention relates to a method for pre-treating activated carbon to be charged in the activated carbon filter in a processing apparatus for producing an activated carbon.

<Conventional technology> Conventionally, in vending machines for coffee, tea, soft drinks, etc., for example, filtration means, sterilization means, heating and / or cooling means, and raw materials of a desired beverage are dissolved in water in the vending machine. Means, or carbonic acid dissolving means, a cup, etc. are provided internally, and by pressing a coin and pressing the select button of the desired beverage, the desired beverage enters the cup by the action of each of the means and is taken out. Has become.

The vending machine uses groundwater or tap water suitable for drinking as supply raw water, and the raw water is first filtered by the above-mentioned filtering means.

As the filtering means, an activated carbon filter using granular or powdered activated carbon is often used. By filtering raw water with the filter, a suspension, organic matter, chromaticity, etc. contained in the raw water can be used. The impurities are removed.

In addition, since the filtered water stays to some extent in a water tank installed in the vending machine, the filtered water immediately after flowing out of the filter is sterilized by a sterilizing means so that bacteria are not generated during the stay.

As the sterilizing means, there is a method in which a sodium hypochlorite solution is injected into filtered water by an injection pump, but a method of treating the filtered water with an electrolytic chlorine generator is also employed.

The electrolytic chlorine generator converts part of the chloride ions contained in the raw water into free chlorine by electrolysis, and determines the energization time and current in advance according to the amount of chloride present in the raw water. Water containing about 0.2 ppm to about 1 ppm of free chlorine.

On the other hand, if the above-mentioned activated carbon is used as it is, it is known that the pH of the initial filtered water becomes alkaline at around 10, and the pH value becomes unsuitable for beverages. When used in a vending machine, it has been used after being treated with hydrochloric acid.

The hydrochloric acid treatment is an operation in which new activated carbon is immersed in an aqueous solution of hydrochloric acid, or an aqueous solution of hydrochloric acid is passed through an activated carbon packed bed and then sufficiently washed with demineralized water.

In the case of activated carbon subjected to such a hydrochloric acid treatment, even if the activated carbon is used in the activated carbon filter, the pH of the filtered water does not increase and the beverage is not unsuitable.

However, when the sterilizing means used in the vending machine is the above-mentioned electrolytic chlorine generator, it has been found that the following problems occur when the above-mentioned activated carbon treated with activated carbon is used.

That is, depending on the amount of chloride ions in the raw water that has been measured in advance, the energizing time and current of the electrolytic chlorine generator are adjusted so that the free chlorine concentration in the treated water of the electrolytic chlorine generator becomes about 0.2 ppm to about 1 ppm. When the raw water is adjusted and treated with an activated carbon filter and then with an electrolytic chlorine generator, the concentration of free chlorine in the treated water rises abnormally for a while from the start of the treatment, and an extreme chlorine odor is generated.

When the activated carbon filter and the electrolytic chlorine generator are incorporated in a vending machine, the chlorine odor described above is transferred to the beverage of the product, which is not preferable because the value of the product is lost.

After investigating the cause of the abnormal increase of free chlorine in treated water for a while from the start of treatment, it was found that filtering raw water with activated carbon treated with hydrochloric acid significantly increased the chloride ion of filtered water from that of raw water. did.

For example, if raw water containing 30 mg / chloride of raw water is filtered with activated carbon treated with hydrochloric acid, the chloride ion in the initial filtered water will vary depending on the total amount of cations in the raw water, but sometimes reaches up to 200 mg /. As it continues, it gradually decreases.

For example, using an electrolytic chlorine generator,
When the amount of generated free chlorine is adjusted to be about 0.2 ppm to about 1 ppm at the time of 30 mg /, when the water in which the chloride ion is increased to 200 mg / is treated with the chlorine generator, the free chlorine concentration is about 5 ppm. Become.

When activated carbon is treated with hydrochloric acid, it is washed with demineralized water until the washing wastewater becomes neutral after the hydrochloric acid treatment. Is thought to be due to the presence of a small amount of anion exchange groups in the activated carbon.

That is, the treatment with hydrochloric acid converts the anion exchange group into a chloride ion form, and the chloride ion is exchanged for a highly selective anion at the beginning of the flow of water, thereby increasing the chloride ion. As the anion exchange group becomes another ion form by the continuation of the water, the amount of increase in chloride ion decreases, and at the point when the ion composition of the raw water reaches an equilibrium point, the amount of chloride ion in the activated carbon filtered water Is equal to that of raw water.

Therefore, if the energization time and current of the electrolytic chlorine generator are changed in accordance with the amount of chloride ions in the activated carbon filtered water which changes in this manner, a constant free chlorine can always be generated. Is extremely complicated, for example, in the case of a vending machine which is operated unattended, it is impossible to do this manually.

In addition, it is conceivable to automatically measure the chloride ion of the water supplied to the electrolytic chlorine generator and automatically vary the energization time and current according to the measured value, but the cost required for this is It is enormous and difficult to put to practical use.

<Problems to be Solved by the Invention> The present invention is a treatment apparatus for producing water containing free chlorine by filtering groundwater or tap water with an activated carbon filter and treating the filtered water with an electrolytic chlorine generator. It is an object of the present invention to provide a method for treating activated carbon that can obtain filtered water without increasing the amount of chloride ions from the beginning of passing water and without increasing pH, from the beginning of passing water. Things.

<Means for Solving the Problems> The present invention provides a process for producing water containing free chlorine by filtering groundwater or clean water with an activated carbon filter and treating the filtered water with an electrolytic chlorine generator. In the apparatus, there is provided a method for treating activated carbon, wherein the activated carbon used in the activated carbon filter is previously treated with an aqueous solution of one or more acids selected from phosphoric acid and sulfuric acid. This is a method for treating activated carbon, wherein the activated carbon used in the filter is treated in advance with an aqueous solution of hydrochloric acid, and then treated with an aqueous solution of one or more acids or salts selected from phosphoric acid and sulfuric acid.

<Action> When activated carbon is treated with hydrochloric acid, as described above, the anion exchange group present in a small amount in the activated carbon becomes a chloride ion form, and the chloride ion becomes more selective for the exchange group during the filtration treatment. By being exchanged for strong anions,
The above-described problem occurs.

Therefore, the present invention performs one of the following two processing methods to avoid this.

One of them is to use a phosphoric acid aqueous solution, a sulfuric acid aqueous solution or a mixed aqueous solution of phosphoric acid and sulfuric acid instead of the conventional hydrochloric acid aqueous solution as an acid washing for preventing a pH rise of the new activated carbon filtered water.

That is, by washing with the above-mentioned acid aqueous solution, the anion exchange group present in the activated carbon can be converted into a phosphoric acid type and / or a sulfuric acid type without being converted into a chloride ion type. Can be reliably prevented from increasing.

Since the selectivity of phosphate ions or sulfate ions to the anion exchange groups is considerably stronger than chloride ions, even if raw water is filtered with activated carbon after the above treatment, chloride ions in the raw water are almost ion-exchanged. Never
Therefore, the amount of chloride ions in the filtered water is almost the same as that of the raw water.

When a new activated carbon is treated with an aqueous solution of phosphoric acid or sulfuric acid, a concentration of the aqueous solution of about 1 to 2% is used, and it is sufficient to use about twice the amount of the activated carbon volume. .

When the acid aqueous solution is brought into contact with activated carbon, the activated carbon may be immersed in the acid aqueous solution, or the acid aqueous solution may be passed through the activated carbon packed bed. After the immersion or the passage, the activated carbon is sufficiently washed with clear water such as demineralized water.

The other is to use an aqueous hydrochloric acid solution as in the prior art for acid washing for preventing the pH of new activated carbon from rising, and then performing the following treatment.

That is, when activated carbon is treated with an aqueous solution of hydrochloric acid, the anion exchange group is converted into a chloride ion form as described above. Treatment with an aqueous solution of an acid salt, an aqueous solution of a sulfate, or an aqueous solution of a phosphate and a sulfate.

As the phosphate and sulfate, salts having high solubility in water, such as sodium salt and potassium salt, are used.

By treating with a phosphoric acid or a salt thereof or a sulfuric acid or a salt thereof after the hydrochloric acid treatment as described above, the exchange group of the chloride ion form in the activated carbon can be replaced with a phosphoric acid form and / or a sulfuric acid form. Achieve the same effect as you did.

In this treatment, the concentration and amount of phosphoric acid or its salt or sulfuric acid or its salt, and the method of contacting with activated carbon may be performed in the same manner as described above.

<Effects> As described above, according to the present invention, the anion exchange group of the activated carbon is not in the chloride ion form, but in the phosphoric acid form or the sulfuric acid form. A large increase in ions can be reliably avoided. In addition, the phosphate group and / or sulfate group exchange group is relatively stable, and even if the raw water is passed through the activated carbon in the ionic form, the chloride ion in the raw water is hardly exchanged. The amount of chloride ions in the filtered water has almost the same value as that of the raw water from the beginning of passing water.

Therefore, even if the filtered water of the filter using the activated carbon subjected to the treatment of the present invention is supplied to an electrolytic chlorine generator having a predetermined energizing time and current corresponding to the amount of chloride ions in the raw water, The concentration of free chlorine does not increase abnormally or the electrolytically treated water does not decrease abnormally.

In addition, as described above, when using the activated carbon that has been subjected to the treatment of the present invention, the amount of chloride ions in the filtered water is substantially the same as that of the raw water. It may be adjusted according to the amount of chloride ions in the raw water, and no special operation is added to the generator.
For example, in the case of a vending machine, there is no need to change the structure inside the machine at all.

Needless to say, the pH of the filtered water of the activated carbon subjected to the treatment of the present invention does not become alkaline.

Examples will be described below to clarify the effects of the present invention.

Example 0.8 Commercially available granular activated carbon (new) 0.8 was immersed in a 1% aqueous phosphoric acid solution 1.6 and left for about 60 minutes with occasional stirring. Next, the supernatant was discarded, and the treated activated carbon was immersed in demineralized water at 50 ° C. of 3.2 for about 30 minutes, the supernatant was discarded, and the operation of washing again with warm demineralized water was repeated about 5 times.
The activated carbon was thoroughly washed.

Fill the filter with the activated carbon treated above, pH 7.3,
Electric conductivity about 290μs / cm, hydrogen carbonate ion 34ppm (CaC
O ₃ ), nitrate ion 6 ppm (CaCO ₃ ), sulfate ion 49 ppm (Ca
CO ₃ ), chloride ion 41ppm (CaCO ₃ ), total cation 130pp
As a result of passing the m (CaCO ₃ ) clean water, the chloride ion in the activated carbon filtered water was about 40 ppm (CaCO ₃ ) immediately after the passage, which was almost the same as the chloride ion amount in the inlet water. Further, the pH of the filtered water was around 7.0 immediately after the passage, and the pH of the filtered water did not show alkalinity.

In addition, almost the same result is obtained when the 1% sulfuric acid aqueous solution or a mixed aqueous solution of phosphoric acid and sulfuric acid having a total acid concentration of 1% is used instead of the 1% phosphoric acid aqueous solution, and the other steps are performed by the same operation. It became.

Further, the same granular activated carbon 0.8 is immersed in a 1% hydrochloric acid aqueous solution 1.6, and left for about 60 minutes with occasional stirring to sufficiently wash the hydrochloric acid. Similarly, a 1% phosphoric acid aqueous solution, a sodium phosphate aqueous solution, Sulfuric acid aqueous solution, sodium sulfate aqueous solution, immersed in 1.6 each, and left with occasional stirring for about 60 minutes, after that, using activated carbon washed with warm demineralized water under the same conditions as above The ions were around 40 ppm (CaCO ₃ ) immediately after passing water, respectively, almost the same as the chloride ion amount in the inlet water, and the pH was around 7.0.

On the other hand, for comparison, the same granular activated carbon as the conventional method was used.
8 was immersed in 1% hydrochloric acid aqueous solution 1.6 and left for about 60 minutes with occasional stirring. Then, the supernatant was discarded, and the treated activated carbon was immersed in 3.2% demineralized water at 50 ° C. for about 30 minutes. The activated carbon treated by repeating the operation of washing with warm demineralized water about 5 times in the same manner was filled in the filter and the same city water was passed through. At 100 ppm (CaCO ₃ ), and thereafter, a phenomenon was observed in which the amount of chloride ions gradually decreased with the passage of water.

Claims (2)

(57) [Claims] 1. A treatment apparatus for producing water containing free chlorine by filtering ground water or tap water with an activated carbon filter and treating the filtered water with an electrolytic chlorine generator. A method for treating activated carbon, wherein the activated carbon is previously treated with an aqueous solution of one or more acids selected from phosphoric acid and sulfuric acid. 2. A treatment apparatus for producing water containing free chlorine by filtering ground water or tap water with an activated carbon filter and treating the filtered water with an electrolytic chlorine generator. A method for treating activated carbon, wherein the activated carbon is treated in advance with an aqueous solution of hydrochloric acid, and then treated with an aqueous solution of one or more acids or salts selected from phosphoric acid and sulfuric acid.