JPS5939383A - Waste water disposal - Google Patents

Abstract

PURPOSE:To enable to remove both of fluorine and boron from waste water containing fluorine and boron, while efficiently regenerating each of chelating and anion-exchange resins at a required time, by circulating said waste water through the beds of the chelating and anion-exchange resins. CONSTITUTION:Waste water containing fluorine and boron is circulated through the beds of chelating and anion-exchange resin to remove both of fluorine and boron from it, and each of the resins is regenerared at a required time. Said chleating resin is pref. Al type, while the anion-exchange resin is pref. OH type. The regeneration of OH type anion-exchange resin used for the removal of boron is performed by circulating a mineral acid such as sulfuric acid through it to exude boron and then a sodium hydroxide-contg. liquid through it to convert it into OH type suited to the adsorption of boron. The regeneration of Al type chelating resin is performed by eluting fluorine with a mineral acid such as sulfuric acid and then circulating an Al salt solution such as aluminum sulfate to replenish Al which has been eluted at the same time.

Description

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

Normally, wastewater from garbage incinerators and flue gas desulfurization wastewater contains
It also contains boron along with fluorine.

As a treatment method for 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 collected and calcium is removed. There are methods such as adding 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. But as for how to treat wastewater containing fluorine and boron at the same time.

Until now, there was no effective way to treat it.

In addition, ion exchange resins (hereinafter referred to as ion exchange resins) have functional groups that chelate fluorine-containing wastewater with metal(s).

It's called chelate resin. ), the method of treatment is as follows:
As is already known, boron-containing wastewater cannot be removed at all by chelate resins.

The present invention enables wastewater containing both fluorine and boron to be
treatment with a seed ion exchange resin to remove both fluorine and boron. The present invention provides a method for treating wastewater containing fluorine and boron by passing it through a chelate resin layer and an anion exchange resin layer, and regenerating each resin when necessary. It is in the processing method.

As the chelate resin in the present invention, diethylenetriamine, triethylenetetramine, or tetraethylenepentamine is used as a functional group in a resin matrix of a styrene compound, a phenol, a condensate of aldehydes, or an acrylic ester compound.

diacetic acid, or aminocarboxylic acids that are reaction products of the above amines and halogenated acetic acids.

Known resins such as those into which alcohol amines such as jetanolamine and diglobanolamine, urea, thiourea, etc. are introduced can be used.

Furthermore, in the present invention, a chelate resin adsorbed with metals such as iron and aluminum is used. In particular, the aluminum type has good adsorption performance, and when regenerated using aluminum sulfate, it is advantageous for subsequent waste liquid treatment. Therefore, it is good for freezing.

As the anion exchange resin, SO4 type or OH type can be used. The S04 type resin can be obtained by regenerating with sulfuric acid or aluminum sulfate, and the OH type resin can be obtained by regenerating with sulfuric acid or aluminum sulfate and then passing a sodium hydroxide solution through the resin.

In the treatment method of the present invention, the OH type does not require pH adjustment even when the pH of the raw water to be treated is near neutral;
This is suitable because it can be subjected to water flow treatment as it is.

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 appropriate aluminum, a compound, etc. 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 lime or the like in advance. Since the pH of the treated water is close to neutral, there is no need to particularly adjust the pH as described above.

A preferred example will be described below 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 and removed from the waste water. Next, the wastewater is passed through an At-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 S2 (space velocity) 5 to 25. At this time, the amount of water flowing through each resin is determined by the ion exchange capacity of the exchange resin used,
The amount of column filling, the content of fluorine and boron in the waste water, and the content of fluorine and boron in the final treated water can be appropriately determined depending on the concentration. Note that the water discharged from the OII type anion exchange resin is slightly alkaline; the water discharged from the 9M type chelate resin is slightly acidic; each exhibits a different pI.
If necessary, it is preferable to add a pH adjuster to make the solution 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 adsorbed fluorine and boron. The passage of the regenerant produces a regenerated waste liquid containing high concentrations of fluorine and boron.

The regeneration of the OH type anion exchange resin used for boron removal is as follows:
After eluting the boron by passing a mineral acid through it, a solution containing hydroxide and lithium is passed through to form the optimal form for boron adsorption.The mineral acid used here is , sulfuric acid, hydrochloric acid, etc. are used, but it is particularly preferable to use a regenerated waste liquid after regenerating the At type chelate resin, since it is possible to utilize a large amount of free sulfuric acid present in the liquid.

A), form Kl/-) Resin is regenerated by eluting fluorine with a mineral acid and then passing an At salt solution through the resin in order to replenish M which is eluted at the same time. As the mineral acid and At 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.

” 1. NaOH regenerated waste liquid, H2SO by regeneration.

A recycled waste liquid and an aluminum sulfate recycled waste liquid are produced, which are mixed and subjected to precipitation and solid-liquid separation processes.

That is, the above-mentioned regenerated waste liquid has a pH of 9 or more, preferably 10μ or more, and more preferably calcium is produced in the presence of an aluminum compound and a calcium compound, and boron and fluorine in the waste liquid are precipitated by co-precipitation or adsorption. move it inside. When the pH is less than 9, calcium aluminate becomes difficult to produce, 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 the calcium compound is determined by the amount of residual aluminum ions in the recycled waste liquid, but is usually at least 5 times the weight of the aluminum compound.

Adjustment of pI-I is carried out by adding an alkaline agent if necessary. When using calcium hydroxide as the calcium agent, it may not be necessary to add a new alkaline agent.

After adjusting p[I in this way, solid-liquid separation is performed in a precipitation tank. Although the form of the precipitate formed is not clear, it is insoluble and has good sedimentation properties, and is easily separated into solid and liquid by natural sedimentation.
Can be removed from the system. The resulting treated water is returned to treated raw water, and the sediment is disposed of as sludge.

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, waste water 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, the recycled waste liquid discharged during 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 used effectively. , Example 1 Fluorine fi5ppm, boron 4.4ppm, chlorine 45000ppm, sulfate ion 9500ppm
Waste incinerator smoke washing and wastewater (pH 7, 8) containing 59 m of on-type anion exchange resin was passed through a column packed with 59 m of on-type anion exchange resin at a space velocity (hereinafter abbreviated as SV) of 10 [-130 I]. The boron content of the treated water was less than t ppm until reaching -Mo.

Next, this treated water was treated with At-type chelate resin for 500 m
Water was passed through the packed column at a rate of SV 10. As a result, the fluorine content in the final treated water was below 1 pI)m until the water flow rate reached 29 tons.

Example 2 The resin used in Example 1 was recycled. First, 1.5 t of sulfuric acid with a concentration of 501/l was added to the Aj type chelate resin layer.
Reproduction @250
ml to the OH type anion exchange resin layer at 100m/,/h
The liquid was passed through at a flow rate of r.

Furthermore, an aluminum sulfate solution with a concentration of 501/z was added to the M-type chelate resin layer. On the other hand, 40.0% Ot was passed through the OH type anion exchange resin layer. ? 50 ml of sodium hydroxide solution having a concentration of β was passed through the tube to complete the regeneration treatment of each resin.

The regenerated waste liquid 5.31% (including 2.751% of washing water) obtained by the process described in 1 contains 354 ppm of fluorine, 24 pptn of boron, and 760 pptn of aluminum.
It contained. Add 40,000 pp of slaked lime to this mixed waste liquid.
As a result of adding l'n and carrying out solid-liquid separation treatment using (1) old 12.6, the amount of fluorine in the clear water was 7.6 ppm and the amount of boron was 0.4 ppm.

[Brief explanation of the drawing]

The drawing is a flowchart 1 showing -(rlJ) of the wastewater treatment method of the present invention.

Claims (3)

[Claims] (1) A method for treating wastewater, which comprises treating wastewater containing fluorine and boron by passing it through a chelate resin layer and an anion exchange tree BW layer, and regenerating each resin when necessary. (2) The above chelate resin is At type, anion exchange resin T
The method for treating wastewater according to claim 1, using a Loll-type wastewater. (3) To regenerate the above resin, a mineral acid is passed through the M-type chelate resin layer, the recycled waste liquid is passed through the OIL-type anion-containing resin layer, and then the A/=-type chelate resin layer contains aluminum acid. 2. The method for treating wastewater according to claim 2, which comprises passing a solution containing sodium hydroxide through the 011 type AniJ transliteration resin layer.