JPS6161879B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater containing fluorine and boron.

Normally, waste water from garbage incinerators and flue gas desulfurization waste water contains boron as well as fluorine.

To treat fluorine-containing wastewater, if it is a concentrated liquid, calcium salts are added to remove it as an insoluble precipitate, and if it is a dilute liquid, it is removed using activated alumina or anion exchange resin, and the concentrated eluate is recovered. There is a method of adding calcium salt to form an insoluble precipitate.

Further, methods for treating boron-containing wastewater include a method of adsorption treatment using an ion exchange resin and a method of forming an insoluble precipitate with aluminum sulfate. However, there has hitherto been no effective method for treating wastewater containing both fluorine and boron.

In addition, ion exchange resins (hereinafter referred to as
It's called Kirei resin. ) is already known, but boron-containing wastewater cannot be removed at all with chelate resins.

The present invention provides a method for treating wastewater containing both fluorine and boron using two types of ion exchange resins to remove both fluorine and boron. Wastewater containing boron is treated by passing it through an Al-type chelate resin layer and an OH-type anion exchange resin, and mineral acid is passed through the Al-type chelate resin layer, and the recycled wastewater is passed through an OH-type anion exchange resin layer. and then passing a solution containing aluminum sulfate through the Al type chelate resin layer and passing a solution containing sodium hydroxide through the OH type anion exchange resin layer to regenerate each of the resins. It's in the processing method.

The chelate resin in the present invention is a resin matrix of a styrene compound, a phenol, an aldehyde condensate, or an acrylic ester compound, and has an amine such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine as a functional group. , iminodiacetic acid,
Alternatively, known resins can be used, such as those into which aminocarboxylic acids, which are reaction products of the above amines and halogenated acetic acid, alcohol amines such as diethanolamine and dipropanolamine, urea, thiourea, etc. are introduced. .

Furthermore, in the present invention, a chelate resin adsorbed with aluminum is used, and the aluminum-type chelate resin has good fluorine adsorption performance, and when regenerated using aluminum sulfate, it is convenient for subsequent waste liquid treatment. Therefore, it is preferable.

As the anion exchange resin layer, OH type can be used. The OH type resin can be obtained by regenerating it with sulfuric acid or aluminum sulfate and then passing sodium hydroxide solution through it.

In the treatment method of the present invention, the OH type is more
Even if the PH of the raw water to be treated is near neutral, there is no need to adjust the PH and the water can be passed through the process as it is, which is preferable.

Although it is not necessary to particularly adjust the pH of the treated wastewater before this treatment step, it is desirable that the pH of the treated wastewater be around neutral. Further, when boron and fluorine form a complex, such as a borofluoride, it is necessary to add an appropriate aluminum compound or the like in advance to decompose the complex. Furthermore, for wastewater containing high concentrations of boron or fluorine, it is desirable to perform a coagulation-sedimentation treatment using coal or the like in advance. The PH of the treated water is almost neutral, so as mentioned above,
There is no need to particularly adjust the pH.

Hereinafter, a preferred example will be explained with reference to a flowchart illustrating it.

The above waste water is first passed through an OH type anion exchange resin layer, and boron is adsorbed on the OH type anion exchange resin layer and removed from the waste water. Then, the wastewater is
Water is passed through the Al-type chelate resin layer, and fluorine is adsorbed onto the resin and removed from the wastewater. The speed of water passing through both resins is not particularly limited, but is usually about 5 to 25 SV (space velocity). At this time, the amount of water flowing through each resin depends on the ion exchange capacity of the exchange resin used, the column packing volume, the fluorine and boron content in the waste water, and the fluorine and boron content in the final treated water. It can be determined appropriately depending on whether the concentration is up to . Note that the water discharged from the OH type anion exchange resin is slightly alkaline, and the water discharged from the Al type chelate resin is slightly alkaline.
Since each resin has a different PH than the acidic one, it is preferable to add a PH adjuster as necessary to make it neutral before passing water through the resin in the subsequent stage.

Each ion exchange resin that has been treated with a predetermined amount of wastewater is backwashed and a regenerant is passed through it to elute the adsorbed fluorine and boron. The passage of the regenerating agent produces a regenerated waste liquid containing high concentrations of fluorine and boron.

To regenerate the OH type anion exchange resin used for boron removal, mineral acid is passed through it to elute the boron.
This is done by passing a solution containing sodium hydroxide through. The mineral acid used here may be sulfuric acid, hydrochloric acid, etc., but it is particularly preferable to use recycled waste liquid after regenerating the Al-type chelate resin because it is possible to utilize a large amount of free sulfuric acid present in the liquid.

To regenerate Al-type chelate resin, after eluting fluorine with mineral acid, in order to replenish Al that is eluted at the same time,
This is done by passing an Al salt solution through. As the mineral acid and Al salt used here, sulfuric acid and aluminum sulfate are preferable since it becomes difficult to remove boron from the recycled waste liquid if hydrochloride is used.

The above regeneration produces NaOH regeneration waste liquid, H ₂ SO ₄ regeneration waste liquid, and aluminum sulfate regeneration waste liquid, which are mixed and subjected to precipitation and solid-liquid separation treatment.

That is, the recycled waste liquid has a pH of 9 or higher, preferably a pH of 10 or higher, and more preferably a pH of 12 in the presence of an aluminum compound and a calcium compound.
By doing the above, calcium aluminate is generated, and boron and fluorine in the waste liquid are transferred to the precipitate by coprecipitation or adsorption. PH is 9
If it is less than that, it becomes difficult to generate calcium aluminate, and the treatment efficiency decreases accordingly. As the calcium compound, calcium compounds such as calcium hydroxide and calcium oxide are used.

The required amount of aluminum compounds is determined by the amount of fluorine and boron in the recycled waste liquid, but usually the recycled waste liquid contains a sufficient amount of aluminum compounds. The required amount of calcium compounds is determined by the amount of residual aluminum ions in the recycled waste liquid, but usually the amount of calcium compounds
At least double the weight.

Adjustment of pH is carried out by adding an alkaline agent if necessary. When using calcium hydroxide as a calcium agent, there are cases where it is not necessary to add a new alkaline agent.

After adjusting the pH in this way, solid-liquid separation is performed in a settling tank. Although the form of the formed precipitate is not clear, it is insoluble and has good precipitability, is easily separated into solid and liquid by natural sedimentation, and can be removed from the system. The obtained treated water is returned to treated raw water,
The sediment will be disposed of as sludge.

In addition, in the treatment method illustrated above, the treated wastewater was passed through the anion exchange resin layer and the chelate resin layer in this order, but in the treatment method of the present invention, which one of the chelate resin layer and the anion exchange resin layer is passed first? The same effect can be obtained.

According to the present invention, wastewater containing fluorine and boron can be removed using two types of ion exchange resins, and each resin can be efficiently regenerated.

Furthermore, in the treatment method of the present invention, recycled waste liquid discharged from resin regeneration can be efficiently treated.

Furthermore, since the anion exchange resin is regenerated using sulfuric acid present in a large amount in the chelate resin regeneration waste liquid, sulfuric acid can be effectively utilized.

Example Fluorine: 65ppm, boron: 4.4ppm, chlorine:
Garbage incinerator smoke wash wastewater (PH7.8) containing 45,000 ppm and 9,500 ppm of sulfate ions was transferred to a column packed with 50 ml of OH type anion exchange resin at a space velocity (hereinafter referred to as SV).
It is abbreviated as ) The boron content of the treated water was less than 1 ppm until the water flow rate reached 30.

Next, this treated water was treated with 500% Al-type chelate resin.
Water was passed through the column packed with ml at a rate of SV10.
As a result, the fluorine content in the final treated water was less than 1 ppm until the water flow rate reached 29.

The resin was then regenerated. First, add 1.5 sulfuric acid at a concentration of 50 g/1 to the Al type chelate resin layer.
250ml of recycled waste liquid obtained by passing the liquid at a flow rate of /hr
was passed through the OH type anion exchange resin layer at a flow rate of 100 ml/hr.

Furthermore, an aluminum sulfate solution (1.0) with a concentration of 50 g/concentration was passed through the Al-type chelate resin layer, and 50 ml of a sodium hydroxide solution with a concentration of 40 g/concentration was passed through the OH-type anion exchange resin layer to regenerate each resin. has ended.

The regenerated waste liquid 5.3 ml (containing 2.75 ml of washing water) obtained by the above treatment contained 354 ppm of fluorine, 24 ppm of boron, and 760 ppm of aluminum.
Add 40,000 ppm of slaked coal to this mixed waste liquid, and
As a result of solid-liquid separation treatment in step 12.6, fluorine in the supernatant water was 7.6 ppm and boron was 0.4 ppm.

[Brief explanation of the drawing]

The drawing is a flowchart showing an example of the wastewater treatment method of the present invention.

Claims (1)

[Claims] 1 Wastewater containing fluorine and boron is passed through an Al-type chelate resin layer and an OH-type anion exchange resin layer for treatment, and a mineral acid is passed through the Al-type chelate resin layer, and the recycled wastewater is converted into an OH-type anion exchange resin layer. The resins are regenerated by passing a liquid through the anion exchange resin layer, then passing a liquid containing aluminum sulfate through the Al type chelate resin layer, and passing a liquid containing sodium hydroxide through the OH type anion exchange resin layer. Characteristic wastewater treatment method.