JP2003245674A - Treatment method for waste water containing harmful metal ion and fluoride ion, and its treatment agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently and simultaneously removing harmful metal ions and a fluoride ion contained in water to be treated. <P>SOLUTION: In the method for removing the harmful metal ions and the fluoride ion contained in the water to be treated, a cationic organic coagulant and rare-earth ions are made to be present in the water, and an alkaline agent is added to the water, thereby removing the harmful metal ions and the fluoride ion simultaneously. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and a removing agent for removing dissolved metal ions and fluorine ions contained in water to be treated.

[0002]

2. Description of the Related Art Conventionally, as a method of removing harmful metal ions contained in water, a method of adding an alkaline substance such as sodium hydroxide or calcium hydroxide to water and precipitating it as a hydroxide is known. ing. Further, as a method for removing the fluorine ions contained in the water to be treated, a calcium coagulation precipitation method in which calcium hydroxide or the like is added to the water to precipitate the fluorine ions as calcium fluoride has been most commonly performed. These methods are effective when harmful metal ions and fluorine ions are separately present in the water, but when harmful metal ions and fluorine ions coexist, the harmful metal ions are hydroxylated with calcium hydroxide. When adding up to pH that can be precipitated as a substance, the amount of calcium necessary for removing fluoride ions is insufficient, so harmful metal ions can be precipitated and removed, but 15 mg / l or 8 mg / l of fluoride ions can be removed.
It is often impossible to remove up to the following. Therefore, several methods are being studied as a method for simultaneously removing harmful heavy metals and fluorine ions. As such a method, after adding a large amount of calcium hydroxide and supplying the required amount of calcium into the water, the amount of increase in pH causes sulfuric acid to reach a predetermined pH.
It is a method of lowering. However, this treatment method has a problem that since a large amount of calcium salt is added, a large amount of sludge is generated, and at the same time, flocs having good sedimentation and / or dehydration properties cannot be obtained, which makes dehydration difficult.

[0003]

An object of the present invention is to provide a method for efficiently and simultaneously removing harmful metal ions and dissolved fluorine ions in the water, and a removing agent used therefor.

[0004]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, in the method for removing harmful metal ions and dissolved fluorine ions contained in the water to be treated, an aqueous solution of a cationic organic coagulant and a basic compound of a rare earth in the water, or a hydrochloric acid solution of a rare earth or When calcium hydroxide is added to the pH to precipitate harmful metal ions as hydroxides by the presence of a sulfuric acid solution, even if the amount of calcium that can be removed by precipitation of the dissolved fluoride ions as calcium fluoride is insufficient, the dissolved There is provided a method for simultaneously removing harmful metal ions and fluorine ions, which is characterized in that fluorine ions are precipitated and separated as a hardly soluble substance. Further, according to the present invention, there is provided a removing agent characterized by comprising a cationic organic coagulant and a rare earth ion when removing dissolved fluorine ions contained in water to be treated.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorine ion removing agent of the present invention (hereinafter simply referred to as a removing agent) comprises a cationic organic coagulant and a rare earth ion.

In the present invention, it is preferable to use a hydroxide of a rare earth or a hydrochloric acid solution of an oxide, a sulfuric acid solution or an aqueous solution of a basic compound of a rare earth. Among the rare earths, lanthanum and cerium are particularly preferable. More preferably, lanthanum is used. These rare earths are used in a liquid state, and in the case of a hydrochloric acid solution, the concentration of the rare earth in the hydrochloric acid solution is 10 to 40%, more preferably 30 to 35% as an oxide. As the cationic organic coagulant, an aqueous solution of cation-modified polyacrylamide, polyacrylic acid dimethylaminoethyl ester, polymethacrylic acid dimethylaminoethyl ester, polyethyleneimine, and chitosan is used, and the solution concentration is 0.01 to 0.5%, preferably 0.02% to 0.2%, more preferably 0.05 to
It is 0.1%.

The rare earth ions mainly used as the removing agent in the present invention can be used alone or in the form of a mixed solution. As the mixed solution, it is preferable to use a mixed solution of lanthanum, cerium, and ytterbium. More preferably, a mixed solution of lanthanum and cerium is preferable. The cationic organic coagulant may be used alone or in the form of a mixed liquid. As the mixed solution, it is preferable to use a cationized modified product of polyacrylamide or a mixed solution of polyacrylic acid dimethylaminoethyl ester, polymethacrylic acid dimethylaminoethyl ester and polyethyleneimine. More preferred is the use of a mixed solution of a cationized modified product of polyacrylamide and polyethyleneimine.

The rare earth element used as the main removing agent in the present invention can be used alone or in the form of a mixed solution. In this case, the rare earth or the solution thereof includes (i) an aqueous solution of lanthanum chloride and / or a hydrochloric acid solution of lanthanum hydroxide or lanthanum oxide or a sulfuric acid solution (ii) an aqueous solution of cerium chloride or ytterbium chloride and / or ytterbium hydroxide or an oxide. It is a mixed solution selected from a hydrochloric acid solution or a sulfuric acid solution of ytterbium and / or an aqueous solution thereof. For example, when a mixed solution of lanthanum chloride and cerium chloride is used, the weight ratio [A] / [B] of the lanthanum chloride solution (A) and the cerium chloride solution (B) is 1 to 1
00, preferably 2 to 50 solutions.

The removing agent can be prepared by removing impurities from ore containing rare earth and then dissolving it in hydrochloric acid. The hydrochloric acid concentration at this time is 0.1 to 12
The concentration is preferably 10 to 12 N, more preferably 11 to 11.5 N, and the concentration of the rare earth is 10 to 40% as an oxide, preferably 20 to 40.
%, More preferably 30 to 35%. The dissolution time is
It suffices if it is completely dissolved, and it is not particularly limited, but about 0.5 to 2 hours is sufficient. The removing agent can be prepared by mixing the obtained rare earth solution and an aqueous solution of a cationic organic coagulant. The mixing ratio of the rare earth solution and the cationic organic coagulant is 1 part by weight of the rare earth,
The amount of the cationic organic coagulant is 0.1 to 5 parts by weight, preferably 0.2 to 2 parts by weight, more preferably 0.5 to 1 part by weight.

When the fluorine ion dissolved in the waste water is removed by using the removing agent of the present invention, when the waste water is acidic or neutral, it is preferable to adjust the pH so that precipitation may occur after adding the removing agent. . The pH is generally in the range of 6-12, preferably in the range of 7-11, more preferably in the range of 8-12.
The range is 10.

When the pH of the water to be treated is adjusted to an alkaline range or an acidic range, a pH adjusting agent is used. Examples of such a pH adjusting agent include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, An alkaline substance such as calcium hydroxide or an acidic substance such as hydrochloric acid, sulfuric acid or nitric acid is used.

In the removing agent of the present invention, it is preferable to use a coagulant together. The aggregating agent in this case is used for floc aggregating, and in such a thing,
In addition to inorganic flocculants such as ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, ferrous polysulfate, and ferric polysulfate,
Cationic modified polyacrylamide, polyacrylic acid dimethylaminoethyl ester, polymethacrylic acid dimethylaminoethyl ester, polyethyleneimine, cationic organic flocculant such as chitosan, nonionic organic flocculant such as polyacrylamide, polyacrylic Anionic organic flocculants such as acids, copolymers of acrylamide and acrylic acid and / or salts thereof are included.

The water to be treated after the pH adjustment step is subjected to solid-liquid separation treatment. As a solid-liquid separation method in this case,
Conventional methods such as filtration separation, centrifugation, sedimentation separation and the like can be mentioned.

[0014]

EFFECTS OF THE INVENTION According to the method of the present invention, dissolved fluorine ions can be efficiently removed at the same time as harmful metal ions contained in water as water to be treated. According to the present invention, the fluorine ion in the water to be treated can be almost completely removed, and the dissolved fluorine ion contained in the treated water after removing the fluorine ion is 15 ppm or less, preferably 8 p.
It is pm or less.

[0015]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

Reference Example 1 0.267 g of lanthanum chloride heptahydrate manufactured by Shin-Etsu Chemical Co., Ltd. and a cationic organic flocculant KP-2 manufactured by Dianitrix Co., Ltd.
Dissolve 0.1 g of 08BH in 100 ml of pure water to prepare a treatment agent (I)
Was prepared.

Example 1 Waste water having a fluorine concentration of 138.33 ppm, a pH of 2.85, a chromium concentration of 36 ppm, and a nickel concentration of 52 ppm in raw water,
After adding 400 ppm of the treating agent (I) of the present invention, the pH was adjusted to 10 with sodium hydroxide. After that, add 3
As a result of analyzing the clear water obtained by adding ppm, the fluorine ion concentration was 9.96 ppm, the chromium concentration was 0.05 ppm, and the nickel concentration was 0.4 ppm.

Example 2 Wastewater having a fluorine concentration of 26.9 ppm, a pH of 6.70, and a copper concentration of 98 ppm in raw water was treated with 200 ppm of the treatment agent (I) of the present invention.
After the addition, the pH was adjusted to 10 with calcium hydroxide. Then, as a result of analyzing the fluorine ion concentration of the clear water obtained by adding 3 ppm of the polymer flocculant, the fluorine ion concentration was 6.57 ppm and the copper concentration was 0.9 ppm.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 1/62 C02F 1/62 C Z (72) Inventor Shinji Wada 1-1-1 East, Tsukuba, Ibaraki Prefecture (72) Inventor Yasuhiro Yukawa 2-1-6 Sengen, Tsukuba-shi, Ibaraki Mitsubishi Corp. Environmental & Development Project Headquarters Environmental & Infrastructure Unit Environmental Resource Research Center F-term (reference) 4D015 BA02 BA05 BA06 BA19 BB09 BB11 CA17 DA13 DA15 DA16 DA30 DB05 DB15 DB24 DB32 DC07 EA15 EA17 EA32 EA35 EA39 4D038 AA08 AB41 AB63 AB65 AB67 AB68 BB13 BB18

Claims (5)

[Claims] 1. A method for removing dissolved metal ions and fluorine ions contained in water to be treated, wherein a cationic organic flocculant and a rare earth ion are present in the water and the pH is adjusted to 7 to 12, A method for removing harmful metal ions and fluorine ions, characterized by precipitating and separating dissolved metal ions and fluorine ions as hardly soluble substances. 2. The rare earth element comprises (i) an aqueous solution of a basic compound or a hydrochloric acid solution or a sulfuric acid solution, or (ii) a hydroxide or oxide solution of a hydrochloric acid or a sulfuric acid solution.
The described removal method. 3. The cationic organic coagulant according to claim 1 or 2, which is a cationized modified product of polyacrylamide, polyacrylic acid dimethylaminoethyl ester, polymethacrylic acid dimethylaminoethyl ester, polyethyleneimine or chitosan. Removal method. 4. The removing method according to claim 1, wherein a flocculant is added. 5. The method according to claim 1, wherein the supplied rare earth ion and cationic organic coagulant is constituted as a drug, and the drug is (i) an aqueous solution of a rare earth basic compound or hydrochloric acid. Solution or sulfuric acid solution,
Or a hydrochloric acid solution or a sulfuric acid solution of a hydroxide or oxide of a rare earth, and (ii) a cationized modified product of polyacrylamide, polyacrylic acid dimethylaminoethyl ester, polymethacrylic acid dimethylaminoethyl ester, polyethyleneimine or chitosan, and A drug comprising a mixture of