JP2003080269A - Method for treating boron-containing water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating boron-containing water by which the amount of chemicals used and the regeneration frequency of an ion exchange resin are reduced and boron can be efficiently removed by flocculation precipitation and/or ion exchange. SOLUTION: (1) In the method for treating boron-containing water by flocculation precipitation, the concentration of boron in the boron-containing water is automatically analyzed and the amount of a flocculant added is automatically controlled. (2) When the boron-containing water is treated by an ion exchange method, the concentration of boron is automatically analyzed and time appropriate to the regeneration of an ion exchange resin is automatically controlled. (3) When the boron-containing water is treated by the ion exchange method after treatment by flocculation precipitation, the concentration of boron is automatically analyzed and the amount of a flocculant added is automatically controlled.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for treating water containing boron. More specifically, the present invention reduces the amount of chemicals used and the regeneration frequency of the ion exchange resin to efficiently remove boron when the boron-containing water is treated by coagulation sedimentation treatment and / or ion exchange treatment. The present invention relates to a method for treating water containing boron.

[0002]

2. Description of the Related Art Boron compounds are used for various purposes such as pharmaceuticals, cosmetics, soaps, electroplating, etc., and the wastewater generated from the manufacturing process of these compounds contains boron. Boron may also be contained in the smoke incinerator wastewater, flue gas desulfurization wastewater, and geothermal power generation wastewater. As a method of treating such boron-containing water, a method of adding aluminum sulfate and calcium hydroxide to remove boron as an insoluble precipitate, a method of adsorbing and removing boron using an ion adsorption resin that selectively adsorbs boron Are known. The amount of boron contained in wastewater often fluctuates over time. For example, in a flue gas desulfurization wastewater of a coal-fired power plant, the amount of boron contained in the wastewater is 1
It varies in the range of 00 to 500 mg / L. In such a case, conventionally, the operation was performed by setting the amount of chemical addition or the ion-exchange resin regeneration frequency according to the maximum boron concentration. Therefore, there is a problem that the amount of chemicals used and the amount of sludge generated are large.

[0003]

DISCLOSURE OF THE INVENTION The present invention reduces the amount of chemicals used and the regeneration frequency of an ion exchange resin efficiently when treating boron-containing water by coagulating sedimentation treatment and / or ion exchange treatment. The object of the present invention is to provide a method for treating boron-containing water capable of removing boron.

[0004]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have analyzed the boron concentration in boron-containing water when treating the boron-containing water whose water quality changes drastically. It was found that the amount of the chemical used and the amount of sludge generated can be reduced by controlling the amount of the flocculating chemical added or the time of regeneration of the ion exchange resin, and the present invention has been completed based on this finding. That is, the present invention provides (1) a method of treating boron-containing water, which comprises automatically analyzing the boron concentration of boron-containing water and automatically controlling the amount of addition of the aggregating agent when the boron-containing water is aggregated and precipitated. (2) A method for treating boron-containing water, which comprises automatically analyzing the boron concentration of the boron-containing water and automatically controlling the regeneration time of the ion-exchange resin when the boron-containing water is subjected to the ion exchange treatment, (3) When performing an ion exchange treatment after the coagulation-precipitation treatment of the boron-containing water, the boron-containing water treatment method is characterized by automatically controlling the boron concentration of the boron-containing water and automatically controlling the addition amount of the aggregating agent, and ( 4) When the boron-containing water is subjected to the coagulation-sedimentation treatment and then the ion exchange treatment, the boron concentration of the boron-containing water is automatically analyzed to automatically control the addition amount of the aggregating agent to perform the coagulation-sedimentation treatment. The boron concentration of the water by the automatic analysis is intended to provide a processing method, the boron-containing water, characterized by automatically controlling the playback timing of the ion exchange resin. Further, as a preferred embodiment of the present invention, (5) the aggregating agent is an aluminum compound and a calcium compound, the method for treating boron-containing water according to the first, third or fourth aspects, (6) an ion exchange resin The method of treating boron-containing water according to item 2, 3, or 4 which is a boron selective adsorption resin.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the first aspect of the method of the present invention, when the boron-containing water is subjected to coagulation-precipitation treatment, the boron concentration of the boron-containing water is automatically analyzed to automatically control the addition amount of the coagulation agent. In the second embodiment of the method of the present invention, when the boron-containing water is subjected to the ion exchange treatment, the boron concentration of the boron-containing water is automatically analyzed to automatically control the regeneration time of the ion exchange resin. In the third aspect of the method of the present invention, when the boron-containing water is subjected to the coagulation-precipitation treatment and then the ion-exchange treatment, the boron concentration of the boron-containing water is automatically analyzed to automatically control the addition amount of the aggregating agent. In the fourth aspect of the method of the present invention, when the ion-exchange treatment after the coagulation-precipitation treatment of the boron-containing water, the boron concentration of the boron-containing water is automatically analyzed to automatically control the addition amount of the aggregating agent,
The boron concentration of the coagulation-precipitation treated water is automatically analyzed to automatically control the time of regeneration of the ion exchange resin. In the method of the present invention,
The method for analyzing the boron concentration of the boron-containing water is not particularly limited, and examples thereof include a mannitol-added caustic soda titration method, a methylene blue absorptiometry method, and an azomethine H absorptiometry method. Examples of the aggregating agent used in the method of the present invention include aluminum compounds such as aluminum sulfate and calcium compounds such as calcium hydroxide. PH of water when a flocculant is added
Is preferably 9 or more, more preferably 10 or more, and further preferably 12 or more. At pH 9 or higher, the presence of the aggregating agent causes boron to be separated and removed as an insoluble precipitate.
In the method of the present invention, in the coagulating sedimentation treatment of boron-containing water, the boron concentration of boron-containing water is automatically analyzed,
The amount of flocculating agent added is automatically controlled according to the target water quality of the treated water. The required amount of the aggregating agent to be added can be determined in advance by a jar test or the like. Automatic control of the amount of aggregating agent added, using a plunger pump, a gear pump, etc. as the agent injection pump, its stroke,
It can be performed by automatically controlling the rotation speed and the like. The pH can be adjusted by adding an alkaline agent as needed. The resulting insoluble precipitate has a good settling property and can be easily solid-liquid separated by natural settling and removed outside the system.

Examples of the ion exchange resin used in the method of the present invention include anion exchange resins and boron selective adsorption resins. Boron in the boron-containing water
When present as orthoborate ion BO ₃ ³⁻ , tetrafluoroborate ion BF ₄ ^−, etc., an anion exchange resin can be preferably used. Anion exchange resin is
Although both a strongly basic anion exchange resin and a weakly basic anion exchange resin can be used, the weakly basic anion exchange resin has better regeneration efficiency. The anion exchange resin is SO _{4 type} or OH type, and boron-containing water can be passed through the ion exchange resin layer to exchange and adsorb boron. Examples of the boron selective adsorption resin include glucamine type ion exchange resin and the like. By using the boron selective adsorption resin, boron in the boron-containing water can be selectively adsorbed and removed. In the method of the present invention, the boron loading amount calculated as the product of the boron concentration (g / m ³ ) and the water flow rate (m ³ ) is analyzed by analyzing the boron concentration in the boron-containing water that passes through the ion exchange resin. When the exchange capacity of the ion exchange resin approaches or when the exchange capacity is reached, the water flow containing boron is stopped by automatic control and the ion exchange resin is regenerated. For example,
Automatically analyze the boron concentration of boron-containing water every hour,
By calculating the amount of boron sent to the ion exchange resin from the product with the water flow rate during that time, and by integrating the amount of boron,
The time of regeneration of the ion exchange resin can be automatically controlled. The anion exchange resin having adsorbed boron can be regenerated by passing a regenerant and eluting the adsorbed boron. As the regenerant, for example, sulfuric acid, hydrochloric acid or the like can be used. By passing sulfuric acid as a regenerant, boron is eluted from the resin and the resin is dissolved in SO ₄
Shaped and played. Furthermore, if necessary, pass an aqueous solution of sodium hydroxide, etc.
Can be shaped.

In the method of the present invention, when the boron-containing water is subjected to the coagulation-precipitation treatment and then the ion-exchange treatment, the boron concentration of the boron-containing water is automatically analyzed to automatically control the addition amount of the coagulation agent to regenerate the ion-exchange resin. Can be performed at regular intervals, or the boron concentration of boron-containing water can be automatically analyzed to automatically control the amount of the flocculant added, and the boron concentration of the flocculation-precipitated water can also be automatically analyzed to obtain an ion-exchange resin. It is also possible to automatically control the time of reproduction. In the coagulation-sedimentation treatment, the boron concentration of the water containing boron is automatically analyzed and the amount of the coagulation agent added is automatically controlled to keep the boron concentration of the coagulation-sedimentation water almost constant. Can be done for each. However, the frequency of regeneration of the ion exchange resin can be further reduced by automatically analyzing the boron concentration of the coagulated sedimentation treated water and automatically controlling the time of regeneration of the ion exchange resin. FIG. 1 is a process system diagram of an embodiment of the method of the present invention.
This embodiment is a coagulation sedimentation treatment of boron-containing water, and the apparatus is a reaction tank 1, an aluminum compound storage tank 2, a calcium compound storage tank 3, an automatic boron concentration analyzer 4, an aluminum compound injection pump 5, a pH sensor 6, a calcium compound. An injection amount control device 7, a calcium compound injection pump 8 and a precipitation tank 9 are provided. The boron concentration of the raw water supplied to the reaction tank 1 is analyzed by the boron concentration automatic analyzer 4, a signal is sent to the aluminum compound injection pump 5, and the amount of the aluminum compound injected from the aluminum compound storage tank 2 is controlled. It A signal is sent to the calcium compound injection pump 8 by the pH sensor 6 and the calcium compound injection amount control device 7, and the calcium compound is injected from the calcium compound storage tank 3 so that the pH of the water in the reaction tank becomes a predetermined value. The amount of is controlled. The water in which boron forms an insoluble precipitate and is precipitated is sent from the reaction tank to the precipitation tank 9 for solid-liquid separation, sludge is withdrawn from the bottom of the precipitation tank, and supernatant water is obtained as coagulation sedimentation treated water.

FIG. 2 is a process flow chart of another embodiment of the method of the present invention. This embodiment is an ion exchange treatment of boron-containing water, and the apparatus includes an ion exchange resin tower 10, an automatic boron concentration analyzer 11, and an ion exchange resin regenerator 12. The boron concentration of the raw water sent to the ion exchange resin tower 10 is analyzed by the boron concentration automatic analyzer 11, and the analyzed value of the boron concentration and the ion concentration measured by a flow meter (not shown) are supplied to the ion exchange tower. The amount of boron loaded on the ion exchange column is calculated from the amount of raw water. The amount of boron loaded in the ion exchange tower is accumulated, and when the accumulated value reaches a predetermined value, a signal is sent to the ion exchange resin regenerator 12 as a time of regeneration of the ion exchange resin, and raw water is passed through. It is stopped and the regeneration of the ion exchange resin is started. When the regeneration of the ion exchange resin is completed, the supply of raw water to the ion exchange resin tower is restarted. FIG. 3 is a process flow chart of another embodiment of the method of the present invention. This embodiment is a method in which boron-containing water is subjected to coagulation-sedimentation treatment and then subjected to ion exchange treatment.
This is a method used as raw water for the ion exchange treatment of the embodiment shown in FIG. In the embodiment shown in this figure, the boron concentration of the treated water of the coagulating sedimentation treatment is analyzed by the boron concentration automatic analyzer 11 and the signal is sent to the ion exchange resin regenerator 12. Is relatively stable, the automatic boron concentration analyzer 11 can be omitted, and the ion exchange resin can be regenerated at regular intervals. According to the method for treating boron-containing water of the present invention, boron can be efficiently removed with a small amount of chemicals used, and the amount of sludge or recycled waste liquid generated can be reduced.

[0009]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Comparative Example 1 Conventionally, in a flue gas desulfurization effluent of a coal-fired power plant whose boron concentration fluctuates within a range of 100 to 500 mg / L, 4.2 wt% of aluminum is adjusted to a maximum boron concentration of 500 mg / L.
A liquid sulfuric acid band containing 35,000 mg / L was added, and slaked lime was added so that the pH became 12.0 to 12.5, and boron was solid-liquid separated as an insoluble precipitate. The boron concentration of the treated water was 20 to 100 mg / L. The amount of slaked lime added was 21,000 mg / L, and the amount of sludge generated was 33,000 mg / L. Example 1 The same flue gas desulfurization wastewater of a coal-fired power plant as in Comparative Example 1 was subjected to coagulation-sedimentation treatment according to the process shown in FIG. For the boron concentration of flue gas desulfurization effluent, install a mannitol-added caustic soda titration automatic boron concentration analyzer in the drainage system.
Analyze each time, and automatically control the stroke of the liquid sulfuric acid band injection pump so that the added amount of liquid sulfuric acid band becomes the amount expressed by the following formula.
Slaked lime was added so as to be 2.0 to 12.5, and boron was solid-liquid separated as an insoluble precipitate. Liquid sulfuric acid band addition amount (mg / L) = 70 × boron concentration of waste water (mg / L) In a continuous treatment for 26 days, the average addition amount of the liquid sulfuric acid band was 8,300 mg / L, and the average addition amount of slaked lime Is 6,200 mg / L, and the average amount of sludge generated is 1100.
It was 0 mg / L. The boron concentration of treated water is 80-100
It was mg / L. The results of Comparative Example 1 and Example 1 are
Shown in the table.

[0010]

[Table 1]

As can be seen from Table 1, the amount of chemicals used and the amount of sludge generated in Example 1 in which the method of the present invention was carried out were one-third or less than those in Comparative Example 1. Example 2 The same neutralization filtered water of flue gas desulfurization wastewater of the same coal-fired power plant as in Comparative Example 1 was subjected to ion exchange treatment by the process shown in FIG. Hydrochloric acid was added to the waste water to adjust the pH to 7 to 9, and filtration was performed using a non-woven fabric to obtain neutralized filtered water. The boron concentration of the neutralized filtered water varied in the range of 150 to 500 mg / L. This neutralized filtered water was mixed with N-methylglucamine type ion exchange resin [Mitsubishi Chemical Corporation, Diaion CRBO2] 1.
Water was passed through the column filled with 0 L at a flow rate of 5 L / h.
The boron concentration of the flue gas desulfurization effluent was automatically analyzed every hour in the same manner as in Example 1, and the accumulated loading amount of boron was 30,0.
When the amount reached 00 mg, regeneration of the ion exchange resin was performed. After continuous treatment for 20 days, the average regeneration frequency is 24
It was once an hour. Moreover, the boron concentration of the treated water was always 0.5 mg / L or less. Comparative Example 2 Under the same conditions as in Example 2, the maximum boron concentration of flue gas desulfurization wastewater was 50 without automatic analysis of the boron concentration of flue gas desulfurization wastewater.
According to the amount of 0 mg / L, the ion exchange resin was regenerated once every 12 hours, and the ion exchange treatment of the neutralized filtered water was performed. The boron concentration in the treated water was always 0.5 mg / L or less.
The results of Example 2 and Comparative Example 2 are shown in Table 2.

[0012]

[Table 2]

As seen in Table 2, the regeneration frequency of the ion exchange resin in Example 2 in which the method of the present invention was carried out was
This is one-half that of Comparative Example 2 in which the regeneration frequency was determined according to the maximum boron concentration in the flue gas desulfurization wastewater, and the amount of chemicals required for regeneration and the amount of regeneration waste liquid generated can be halved. Example 3 The same flue gas desulfurization wastewater of the coal-fired power plant as in Comparative Example 1 was subjected to coagulation sedimentation treatment and ion exchange treatment by the steps shown in FIG. However, the automatic boron concentration analyzer 11 was not used, and the ion exchange resin was regenerated at regular intervals.
The coagulation-sedimentation treatment was performed in the same manner as in Example 1, and the boron concentration was 8
0 to 100 mg / L of coagulated sedimentation treated water was supplied to the column packed with the same ion exchange resin as in Example 2. Regeneration of the ion exchange resin was performed every 60 hours. In continuous treatment for 20 days, the concentration of boron in treated water is always 0.5 mg.
/ L or less. Example 4 The same flue gas desulfurization wastewater of a coal-fired power plant as in Comparative Example 1 was subjected to coagulation sedimentation treatment and ion exchange treatment by the steps shown in FIG. The coagulating sedimentation treatment is performed in the same manner as in Example 1,
The coagulation-sedimentation-treated water having a boron concentration of 80 to 100 mg / L was supplied to the column packed with the same ion exchange resin as in Example 2. The boron concentration of the coagulation-sedimentation-treated water was automatically analyzed every hour in the same manner as in Example 1, and the cumulative loading amount of boron was 3
Regeneration of the ion exchange resin was carried out when it reached 000 mg. In the continuous treatment for 20 days, the average regeneration frequency was once every 65 hours. Moreover, the boron concentration of the treated water was always 0.5 mg / L or less. The results of Examples 3 to 4 are shown in Table 3.

[0014]

[Table 3]

As shown in Table 3, when the flue gas desulfurization wastewater is subjected to coagulation sedimentation treatment and ion exchange treatment, the boron concentration of the treated water is always 0.5 mg / L or less, and the treated water of good quality is obtained. Has been obtained. Example 3 in which the ion exchange resin was regenerated every 60 hours, and the boron concentration of the coagulation-sedimentation-treated water was automatically analyzed, and the cumulative loading amount of boron was 30,0.
In Example 4 in which the ion exchange resin was regenerated when it reached 00 mg, there was no difference in the boron concentration of the treated water, but in Example 4, the regeneration frequency of the ion exchange resin was slightly lower than in Example 3. Has become.

[0016]

EFFECTS OF THE INVENTION According to the method for treating boron-containing water of the present invention, boron can be efficiently removed with a small amount of chemicals used, and the amount of sludge and recycled waste liquid can be reduced.

[Brief description of drawings]

FIG. 1 is a process system diagram of an embodiment of the method of the present invention.

FIG. 2 is a process flow chart of another embodiment of the implementation of the method of the present invention.

FIG. 3 is a process flow chart of another embodiment of the method of the present invention.

[Explanation of symbols]

1 reaction tank 2 Aluminum compound storage tank 3 calcium compound storage tank 4 Boron concentration automatic analyzer 5 Aluminum compound injection pump 6 pH sensor 7 Calcium compound injection amount control device 8 Calcium compound infusion pump 9 settling tank 10 Ion exchange resin tower 11 Boron concentration automatic analyzer 12 Ion exchange resin regeneration device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsutsuaki Yamaura             2-2-1 Nakayama, Aoba-ku, Sendai City, Miyagi Prefecture             Tohoku Electric Power Co., Inc. Research and Development Center (72) Inventor Takeshi Sato             Kurita, 3-4-3 Nishi-Shinjuku, Shinjuku-ku, Tokyo             Industry Co., Ltd. (72) Inventor Yoshihiro Keito             Kurita, 3-4-3 Nishi-Shinjuku, Shinjuku-ku, Tokyo             Industry Co., Ltd. (72) Inventor Hiroyuki Asada             Kurita, 3-4-3 Nishi-Shinjuku, Shinjuku-ku, Tokyo             Industry Co., Ltd. F-term (reference) 4D015 BA19 BA21 BB05 CA20 DA05                       DA22 EA15 EA32 FA02 FA12                       FA22                 4D025 AA09 AB33 BA13 BB02 CA02                       CA05 CA06 DA10                 4D038 AA08 AB25 BA04 BA06 BB06                       BB08

Claims (4)

[Claims] 1. A method for treating boron-containing water, which comprises automatically analyzing the boron concentration of boron-containing water to automatically control the addition amount of the aggregating agent when the boron-containing water is subjected to coagulation-precipitation treatment. 2. A method for treating boron-containing water, which comprises automatically analyzing the boron concentration of the boron-containing water and automatically controlling the regeneration time of the ion-exchange resin when the boron-containing water is subjected to the ion exchange treatment. 3. Treatment of boron-containing water, characterized in that when the boron-containing water is subjected to coagulation-precipitation treatment and then subjected to ion-exchange treatment, the boron concentration of the boron-containing water is automatically analyzed to automatically control the addition amount of the aggregating agent. Method. 4. When the boron-containing water is subjected to the coagulation-precipitation treatment and then the ion exchange treatment, the boron concentration of the boron-containing water is automatically analyzed to automatically control the addition amount of the coagulation agent to automatically adjust the boron concentration of the coagulation-precipitation treated water. A method for treating boron-containing water, comprising analyzing and automatically controlling the time of regeneration of the ion exchange resin.