JP2007029925A - Treating method of boron-containing waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating method capable of removing boron in boron-containing waste water by a coagulating sedimentation method. <P>SOLUTION: In this boron-containing waste water, a phenolic hydroxyl group-containing compound, a compound derived from persimmon juice, tea, mimosa, quebracho, or chestnut, is added to boron-containing waste water to form a complex, then, an insolubilizer like a calcium compound, a magnesium compound, formaldehyde, acetaldehyde, gelatin, glue or the like, is added to coagulate and precipitate boron together with the complex to remove boron. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for treating boron-containing wastewater.

  Boron compounds are widely used in the fields of dyes, pigments, medicines, cosmetic raw materials, preservatives, photography, soap, glass, plating, etc., and wastewater discharged from these manufacturing processes contains boron compounds. ing. Further, boron compounds are also contained in radioactive liquid waste generated from nuclear power plants, geothermal power generation water, flue gas desulfurization effluents, waste incineration sewage effluents, and the like.

  Although boron is considered an essential element for plants, excessive application is known to inhibit its growth, and in Japan, extremely strict drainage standards of 1-2 mg / L or less are established by regulations. There are places.

  As a method of treating such boron-containing wastewater, a method of removing as an insoluble precipitate with aluminum sulfate or slaked lime (first method), a method of adsorbing with anion exchange resin or boron selective ion exchange resin (first method). Method 2), extraction with a solvent (third method), and treatment with a reverse osmosis membrane (fourth method) are known.

  Among these, as the first method, there is a method in which boron is coprecipitated by adding an excess amount of aluminum ions and calcium hydroxide and making the solution alkaline (see, for example, Patent Document 1 and Patent Document 2). ). Furthermore, a method of treating low-concentration boron wastewater by using a rare earth element hydrous oxide has also been proposed (see, for example, Patent Document 3).

  Of these, the second and third methods utilize the property that boron forms a complex with a hydroxyl group-containing compound such as saccharides or alcohols. In the second method, the functional group containing a hydroxyl group is insoluble. Examples of the resin introduced into the polymer include a boron-adsorbing resin in which gallic acid is immobilized on an anion exchange resin (see, for example, Patent Document 4), a boron selective ion exchange resin in which a methylglucamine group is introduced, cellulose, and a chitosan derivative. Boron adsorbents using carbon have been proposed. In the third method, alcohols such as 2-ethylhexanol, aliphatic 1,3-diol, and aliphatic 1,2-diol have been proposed as a solvent having a hydroxyl group as an extractant (for example, Non-patent document 1).

  In addition, a method in which the coagulation precipitation method and boron removal by an anion exchange resin or a boron selective ion exchange resin are combined has also been proposed (see, for example, Patent Document 5).

Note that phenolic compounds such as gallic acid are known to complex with boric acid (see, for example, Patent Document 4), but some of these compounds complex with calcium ions and the like such as tannin. It is well known that some are insolubilized.
JP 2004-283731 A Japanese Patent Publication No.58-15193 Japanese Patent Publication No. 3-22238 JP 2000-144061 A "Water and Wastewater", Industrial Water Research Committee, 1999, VOL.41, No.10, pp53-58 JP 58-193786 A

  However, the conventional techniques have the following problems. In the first method, since the removal efficiency of boron is low, in order to keep the boron concentration in the treatment liquid low, it is necessary to increase the amount of aggregating agent such as aluminum sulfate, and a large amount of sludge is generated. There was a problem.

  In the second method, the boron selective ion exchange resin is expensive and generally regenerated and repeatedly used. However, when the resin is regenerated and used, the treatment of the regenerated waste liquid is performed by the first method. The same problem as in the first method occurred.

  In the third solvent extraction method, when applied to wastewater treatment, there is a problem of organic contamination due to dissolution of the extraction solvent in water. Therefore, it is necessary to perform solvent treatment as a post-treatment of wastewater from which boron has been extracted. It was.

  Furthermore, in the fourth method, the generally used reverse osmosis membrane has a low removal rate for boron compounds of 50 to 60%, and requires a multi-stage apparatus for processing below the regulation value of drainage, and the initial cost. There was a problem such as becoming excessive.

  Even in the method of combining the coagulation sedimentation method and the resin, the removal efficiency in the first coagulation sedimentation method is low, so that there is a problem that the load on the adsorption resin in the subsequent stage is high and the amount of waste liquid is not sufficient. Further, even when the coagulation sedimentation method is used for the resin regeneration waste liquid treatment, it is necessary to return the treated water to the resin tower again for treatment because the waste water for regeneration waste water contains high concentration of boron. For this reason, this method still has problems such as an increase in equipment, and it is necessary to increase the boron removal efficiency in the coagulation precipitation method in any method.

  In the method using a rare earth element hydrated oxide, a water-insoluble solid called a hydrated oxide is used, so that the treatment efficiency is poor. There is a problem that it is necessary and the sedimentation property of the generated sludge is poor.

  On the other hand, as described above, boron has a property of forming a complex with a hydroxyl group-containing compound such as saccharides, alcohols, and phenolic compounds (see Table 98/42910, Patent Document 4). However, since such a hydroxyl group-containing compound is generally water-soluble, it is difficult to separate boron from an aqueous solution. On the other hand, when poorly soluble polysaccharides or alcohols are used, the number of hydroxyl groups is reduced as compared with water-soluble ones, and there is a problem that the boron removal efficiency is lowered.

  In view of the above-mentioned problems, the present invention provides a method for treating boron-containing wastewater that can quickly and efficiently remove boron from boron-containing wastewater and that can suppress the amount of sludge generated. It is intended.

  As a result of intensive studies to solve such problems, the present inventors have found that a complex of boron is added by adding an insolubilizing agent for the phenolic hydroxyl group-containing compound to the complex of the phenolic hydroxyl group-containing compound and boron. It is possible to precipitate and remove boron efficiently in a very short time, and it is possible to reduce the amount of sludge because it is effective with a small addition amount. As a result, the present invention has been found.

  In addition, the essence of the action of the insolubilizing agent in the present invention is merely insolubilization of the complex, and as described in Patent Document 1, it does not directly act on boron to generate a precipitate. It is fundamentally different from existing technology.

  That is, the gist of the present invention is a treatment method for boron-containing wastewater characterized by adding a phenolic hydroxyl group-containing compound and an insolubilizing agent to boron-containing wastewater to produce a precipitate containing boron. Yes, preferably after the addition of the phenolic hydroxyl group-containing compound to the boron-containing wastewater, and then adding the insolubilizing agent to produce a boron-containing precipitate, preferably the boron-containing wastewater treatment method, , Phenolic hydroxyl group-containing compounds are phenol, p-quinol, m-quinol, catechol, pyrogallol, naphthoquinol, anthraquinol, chlorogenic acid, gallic acid, ellagic acid, lignin-based substances, flavonoid-based substances and basic skeletons thereof A monomer of one or more compounds selected from the group consisting of: It is a ligomer and / or polymer, and preferably, the phenolic hydroxyl group-containing compound is a compound derived from a natural product, and preferably, the phenolic hydroxyl group-containing compound is a tannin, lignin or catechin derived from a plant. In any of the above-mentioned compounds, and preferably, the method for treating a boron-containing wastewater, wherein the phenolic hydroxyl group-containing compound is a compound derived from any one of persimmon, tea, mimosa, kebratcho or chestnut.

  Furthermore, the present invention is preferably the boron-containing wastewater treatment method described above, wherein the insolubilizing agent is preferably an ionic substance, and preferably, after a boron-containing precipitate is produced, solid-liquid separation is performed. The method for treating boron-containing wastewater as described above, wherein treated water having a low boron concentration is obtained.

  According to the present invention, boron can be quickly and efficiently adsorbed and removed from boric acid-containing wastewater with a small amount of chemical addition, which is problematic in the treatment of boron using the coagulation precipitation method in water treatment facilities. In addition, it can solve the problems of large sludge generation and high cost. Furthermore, since the reaction proceeds quickly, it is possible to expect improvement in working time and processing capacity. Moreover, when processing resin regeneration waste liquid, since the density | concentration at the time of returning a processing liquid to a resin tower can be reduced, reduction | decrease of an installation etc. can be anticipated.

  Hereinafter, the present invention will be described in detail.

As boron-containing wastewater to be treated in the present invention, wastewater discharged from manufacturing processes in the fields of dyes, pigments, medicines, cosmetic raw materials, preservatives, photographs, soap, glass, plating, etc., and boron compounds are adsorbed Examples of such waste liquids include regeneration waste liquids from resins and other boron compounds. Usually, boron compounds in the form of H ₃ BO ₃ , B (OH) ₄ or salts thereof are contained depending on the pH.

  The boron concentration in the boron-containing wastewater to be treated in the present invention is not particularly limited, and may be any boron concentration in the range of 2 to 5,000 mg / L. It is preferably in the range of 2 to 200 mg / L.

  In the treatment method of the present invention, it is preferable to proceed with the treatment while maintaining the pH of the boron-containing wastewater to be treated within a certain range. The pH range is preferably 2.0 to 14.0, more preferably 5.0 to 12.5, and most preferably 8.0 to 11.0.

  Examples of the reagent used for adjusting the pH include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and ammonia. In addition, those which act as a complex insolubilizer such as iron sulfate and calcium hydroxide are not preferable. This is because the processing ability is reduced by, for example, generating a precipitate before the complex formation between the complex forming agent and boron occurs. In addition, in order to make it react efficiently, it is desirable to process with stirring throughout the processing operation. A method of stirring is not particularly limited, but a method using a stirring blade which is usually used may be used.

In this invention, after adjusting pH as needed as mentioned above, a phenolic hydroxyl group containing compound is added to boron containing waste_water | drain. The phenolic hydroxyl group-containing compound used in the present invention only needs to have at least one hydroxyl group in one benzene ring, but preferably two or more, more preferably at least two hydroxyl groups are adjacent to each other. It is better to be.
Examples of such compounds include phenol, p-quinol, m-quinol, catechol, pyrogallol, naphthoquinol, anthraquinol, chlorogenic acid, gallic acid, ellagic acid, and monomers of chemical substances based on these and these monomers. Includes oligomers and polymers.

  In addition, substances derived from natural products such as plant polymers or oligomers such as lignin and lignan, and monomers or precursors thereof such as p-coumaric acid, caffeic acid, ferulic acid, hydroxyferulic acid, sinapinic acid, etc. In addition, chemical substances having these as basic skeletons and glycosides thereof are included.

In addition, flavan derivatives having a C ⁶ -C ³ -C ⁶ structure, such as catechin, epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate, quercetin, daidzein, etc., which are also natural products, so-called In addition to substances having a flavonoid-based basic skeleton, monomers of these chemical substances, oligomers and polymers thereof, and glycosides thereof are included.

  In addition, monomers, oligomers, polymers and the like of amino compounds such as tyrosine and dopa, or amine compounds such as dopamine are also included.

  Naturally-derived substances also include tannin, which is one form of the above substances. For example, geranin and eugenin called hydrolyzable tannin, ratanin called condensed tannin, procyanidin, quebraco tannin, wattle tannin, mangrove tannin , Sprue stannin, gambil tannin, red catechin, oak bark tannin. The origin of tannin includes plants such as tea, astringent, apple, quebracho, cod, chestnut, pentaploid, oak, mimosa, Gambia, and boram, including extracts and processed products thereof. These are commercially available in the form of powder or liquid. For example, an extract of astringent persimmon, a so-called persimmon astringent is commercially available as amber tannin H-1 from Kametaro Iwamoto Shoten, and is a tannin derived from other plants. As for mimosa, quebratcho and chestnut, those imported from overseas are commercially available in powder form from Kawamura Tsusho Corporation. For tea, in addition to commercially available tea leaves, use tea leaves.

  Among these, oligomers and polymers of ellagic acid, oligomers and polymers of dopa, oak bark tannin, mangrove tannin, red catechin, lignan, flavonoid-based compounds, gallic acid monomers and oligomers and polymers, caffeic acid Oligomers and polymers of chlorogenic acid, oligomers and polymers of chlorogenic acid, oligomers and polymers of sinapinic acid, astringent, tea, apple, quebratcho, chestnut, mimosa, lignin, catechin oligomers and polymers are preferred, lignan and flavonoid basic skeletons Compounds with gallic acid monomers and oligomers and polymers, caffeic acid oligomers and polymers, chlorogenic acid oligomers and polymers, sinapinic acid oligomers and polymers, astringent, tea, apple, quebratcho, che Tonatto, Mimosa, lignin, more preferably oligomers and polymers of catechins, astringent persimmon, tea, Keburatcho, Chestnut, mimosa, lignin and oligomers and polymers of catechins most preferred.

  Examples of the shape of the phenolic hydroxyl group-containing composition used in the present invention include liquids such as liquids and aqueous solutions, powders, flakes, and slurries. From the standpoint of ease of use, solid compounds are It is desirable to dissolve in water before use and use it as an aqueous solution. It is desirable that these are as dark as possible from the viewpoint of use. The concentration at this time varies depending on the substance used, but it is generally desirable that the concentration be 20,000 ppm or more.

Among these substances, most of the substances other than the monomer have a complicated shape, so it is practically impossible to determine the concentration and molecular weight. Therefore, in describing the present invention in detail, for the sake of convenience, the concentration is determined using the Folin Dennis method in order to make the standard constant. The standard substance is gallic acid, and the concentrations of all samples are evaluated by the concentration per gallic acid.
Hereinafter, the Folin Dennis method will be described.
[Preparation of Folin Dennis reagent]
To 700 mL of pure water, 100 g of sodium tungstate dihydrate, 20 g of phosphomolybdic acid and 50 mL of phosphoric acid are added and dissolved, and then refluxed for 2 hours. After cooling, use a constant volume of 1 liter.
[Preparation of standard solution]
Collect 10 mg of gallic acid in a 100 mL volumetric flask. 80% methanol is added to this and dissolved to obtain a standard solution.
[Measuring method]
Add 200 μL of the sample solution for analysis to a test tube containing 3.2 mL of water. To this, 200 μL of Folin Dennis reagent is added and stirred, and then 400 μL of saturated sodium carbonate solution is added and left for 30 minutes. The 700 nm absorption of this solution is measured. In the blank, water is added in place of the Folin Dennis reagent, and the measurement is performed in the same manner. For standard substances, measure the stock solution after diluting it in several steps to create a standard curve.
[Calculation]
After subtracting the blank value from the OD value of the sample solution, the measured value is calculated from the standard curve. For one reagent, an average value of measured values of three individuals is obtained.

  As the addition amount of the phenolic hydroxyl group-containing compound in the present invention, the boron removal rate tends to improve as it is added in a large amount. However, since the boron removal amount per drug decreases, naturally the amount of sludge generated tends to increase. There is. The optimum amount of addition varies depending on the complex formation constant between each substance and boron. Usually, when removing boron by 50% or more, the molar concentration in terms of gallic acid is 0.1 to 100 times that of boron. It is desirable to add so that it may become a density | concentration, the density | concentration range of 0.2-50 times is still more desirable, and it is optimal to add in the density | concentration range of 0.5-10.0 times.

  In the present invention, after adding the phenolic hydroxyl group-containing compound, it is preferable to stir so that the solution becomes uniform. A method of stirring is not particularly limited, but a method using a stirring blade which is usually used may be used.

  As described above, the phenolic hydroxyl group-containing compound forms a boron complex by adding the phenolic hydroxyl group-containing compound to the boron-containing waste water. In most cases, this complex does not aggregate, and it is difficult to separate boron from an aqueous solution as it is. Therefore, in the present invention, it is necessary to add a complex insolubilizer. These may be added at the same time, but it is desirable to add an insolubilizing agent after adding the phenolic compound in order not to lower the processing capacity.

  Examples of the insolubilizer used in the present invention include ionic compounds, oxidizing agents, and polymer compounds. Specific examples of the ionic compound include calcium ion, magnesium ion, iron ion, and the compound to be added may be chloride, sulfate, carbonate, hydroxide or the like. Specific examples of the oxidizing agent include aldehyde compounds such as formaldehyde and acetaldehyde, chlorine-based oxidizing agents such as chlorous acid and hypochlorous acid, potassium permanganate, manganese dioxide, and potassium dichromate. Specific examples of the polymer compound include proteins such as BSA, casein, gelatin, and glue.

  These may be used alone or in combination.

  Of these, hypochlorous acid, potassium permanganate, casein, iron ion compound, perchloric acid, calcium compound, magnesium compound, formaldehyde, acetaldehyde, gelatin, and glue are preferable, and iron ion compound, perchloric acid, calcium Compounds, magnesium compounds, formaldehyde, acetaldehyde, gelatin and glue are more preferred, and calcium compounds, magnesium compounds, formaldehyde, acetaldehyde, gelatin and glue are most preferred.

  The amount of insolubilizer added varies depending on the concentration of boron in the wastewater to be treated and the concentration of the phenolic hydroxyl group-containing compound to be added. Usually, when removing 50% or more of boron, It is desirable to add so that it may become a density | concentration of 0.01-50 in conversion of molar concentration, the density | concentration range of 0.05-25 is still more desirable, and the density | concentration range of 0.1-5.0 is the most desirable. In addition, precipitation does not arise even if only an insolubilizing agent is added to a boron solution with the addition density | concentration of this invention.

  In the present invention, after adding the insolubilizing agent, it is preferable to stir so that the solution becomes uniform. A method of stirring is not particularly limited, but a method using a stirring blade which is usually used may be used.

  By adding the above-described complex insolubilizing agent and stirring, precipitate of the complex is formed. In the present invention, a polymer flocculant or the like may be added in some cases in order to promote the formation of precipitates. The polymer flocculant used here may be appropriately selected from anionic polymer flocculants, nonionic polymer flocculants, cationic polymer flocculants, amphoteric polymer flocculants, and the like. Among these, anionic polymer flocculants are preferable, and for example, UNIFLOKER (R) (manufactured by Unitika Ltd.) can be used. Among the unif lockers, the UF-100 series, UF-200 series, UF-300 series, and UF-700 series are preferable. Of these, the UF-100 series is more preferable, and the UF-105 is most preferable. The final concentration range of the polymer flocculant is preferably from 0.1 to 50 ppm, more preferably from 0.5 to 20 ppm, and most preferably from 1.0 to 10.0 ppm.

  In the treatment method of the present invention, although depending on the amount of boron-containing wastewater to be treated, these reactions are almost completed within 5 minutes, and it takes about 30 minutes by the conventional method (for example, see Patent Document 3). The processing time required can be greatly reduced. The produced precipitate is easily separated into solid and liquid by natural sedimentation or the like and discharged out of the system.

  Hereinafter, the present invention will be described specifically by way of examples. In the examples, the boron concentration was measured using an ICP emission spectrometer (manufactured by Nippon Jarrell-Ash). The parameters are as follows: Measurement wavelength: 208.959 nm, high frequency output: 1150 watts, auxiliary flow rate 0.5 L / min, nebulizer flow rate: 28.06 psi, pump speed 130 rpm, purge time 90 seconds.

Example 1
Using boric acid, 40 mL of model wastewater containing 15.8 mg / L (1.4 mM) of boron was prepared. While stirring this, the pH is adjusted to 9.0 using NaOH or HCl, and a concentration of 1,500 in terms of gallic acid is used as a complexing agent with boron, using astringent astringent solution (membrane separation purified tannin H-1 manufactured by Kametaro Iwamoto Shoten). It added so that it might become mg / L (8.9 mM). After stirring for 1 minute, a CaCl ₂ solution was added so that the concentration of Ca ²⁺ as an insolubilizing agent was 2,400 mg / L (60 mM), and an insoluble precipitate was rapidly formed. The produced precipitate was centrifuged and the boron concentration in the supernatant was measured. As a result, it was 1.4 mg / L (0.13 mM), and the boron removal rate was 91%.

Comparative Example 1
Using boric acid, 250 mL of model wastewater containing 19.6 mg / L of boron was prepared. The pH at this time was 5.7. While stirring this, 5,000 mg / L of a boron fixing agent UML-9000 (manufactured by Unitika) was added, and 2,400 mg / L of polyaluminum chloride was further added. Thereafter, the pH was adjusted to 9.0 using NaOH, 1 mg of a polymer flocculant (manufactured by Unitika, UNIFLOKER 105) was added, and the mixture was stirred for 30 minutes to produce an insoluble precipitate. The produced insoluble precipitate was filtered with a filter paper (No. 1), and the boron concentration of the filtrate was measured. As a result, it was 7.7 mg / L, and the boron removal rate was 61%.

Example 2
Model wastewater 40mL containing boron 19.0mg / L was made using boric acid. While stirring this, the pH was maintained at 9.0 using NaOH, and the chestnut solution was added thereto so that the concentration in terms of solid content was 2,000 mg / L. Furthermore, a CaCl ₂ solution was added as an insolubilizing agent so that the concentration of Ca ²⁺ was 2,400 mg / L, and an insoluble precipitate was rapidly generated. Further, 80 μL of a polymer flocculant (manufactured by Unitika, UNIFLOKER 105) was added to promote precipitation. The produced precipitate was centrifuged and the boron concentration in the supernatant was measured. As a result, it was 8.0 mg / L and the boron removal rate was 60%.

As is clear from the above results, by using a phenolic hydroxyl group-containing compound and a substance that insolubilizes it in combination, it becomes possible to rapidly coagulate and precipitate boron with a small amount of chemical addition, greatly improving the boron removal efficiency. Can be improved.

Claims (8)

A method for treating boron-containing wastewater, comprising adding a phenolic hydroxyl group-containing compound and an insolubilizing agent to wastewater containing boron to generate a precipitate containing boron. The method for treating boron-containing wastewater according to claim 1, wherein after adding the phenolic hydroxyl group-containing compound to the wastewater containing boron, an insolubilizing agent is then added to generate a precipitate containing boron. The phenolic hydroxyl group-containing compound is phenol, p-quinol, m-quinol, catechol, pyrogallol, naphthoquinol, anthraquinol, chlorogenic acid, gallic acid, ellagic acid, lignin-based substance, flavonoid-based substance and these as basic skeleton The method for treating boron-containing wastewater according to claim 1, which is a monomer, oligomer and / or polymer of one or more compounds selected from the group consisting of chemical substances. The method for treating boron-containing wastewater according to any one of claims 1 to 3, wherein the phenolic hydroxyl group-containing compound is a compound derived from a natural product. The method for treating boron-containing wastewater according to claim 4, wherein the phenolic hydroxyl group-containing compound is any one of tannin, lignin and catechins derived from plants. The method for treating boron-containing wastewater according to claim 5, wherein the phenolic hydroxyl group-containing compound is a compound derived from any one of persimmon astringent, tea, mimosa, quebratcho, or chestnut. The method for treating boron-containing wastewater according to any one of claims 1 to 6, wherein the insolubilizing agent is an ionic substance. The method for treating boron-containing wastewater according to any one of claims 1 to 7, wherein after producing a precipitate containing boron, solid-liquid separation is performed to obtain treated water having a low boron concentration.