JPH06304573A - Treatment method of wastewater containing fluorine and arsenic - Google Patents

Abstract

(57) [Summary] [Purpose] Fluorine and arsenic in wastewater are removed by combining specific coagulation-sedimentation treatment, fluorine adsorption treatment and arsenic adsorption treatment, and adsorption of fluorine adsorbent and arsenic adsorption is performed. Make effective use of abilities. [Structure] Waste water containing fluorine and arsenic is subjected to coagulation-precipitation treatment using aluminum sulfate or calcium chloride, followed by adsorption treatment using an aluminum-supported resin, and then zirconium-supported resin or a rare earth element hydrated oxide. It is used for adsorption treatment to remove fluorine and arsenic contained in wastewater.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for treating wastewater containing fluorine and arsenic. More specifically, the present invention relates to a method for treating fluorine- and arsenic-containing wastewater capable of increasing the efficiency of the adsorption capacity of the fluorine-adsorbent and the arsenic-adsorbent and completely removing fluorine and arsenic.

[0002]

2. Description of the Related Art Waste water generated in semiconductor manufacturing processes, garbage incinerators, etc. sometimes contains fluorine and arsenic. The emission standard for fluorine is currently 15 ppm, but regulations are being tightened.
Arsenic has long been known for its toxicity, especially trivalent arsenic is highly toxic, and is known to cause gastrointestinal disorders, nerve and vascular disorders, and its environmental standard is 0.05 ppm. It is about to be further strengthened to 0.01 ppm or less. Therefore, it is desired to completely remove these from wastewater containing fluorine and arsenic.

Various methods are conventionally known for removing harmful substances from wastewater. For example, as a method for removing fluorine in waste water, a neutralization coagulation-sedimentation method using a calcium compound, a method using a basic anion exchange resin, or a method using an aluminum salt type chelate resin (JP-A-57-107287). ), And a method using a rare earth metal-supporting resin (Japanese Patent Laid-Open No. 61-192340). On the other hand, as a method of removing arsenic in wastewater,
Coagulation-precipitation method using iron compound or method using zirconium-supporting cation exchange resin (Chemical Society of Japan, 3
79, 1981), a method using a hydrated oxide of a rare earth element (JP-A-61-187931) and the like are known.

However, these methods have various problems. For example, the coagulation-sedimentation treatment method has a drawback that a large amount of sludge is generated, and also has a drawback that fluorine cannot be treated to a low concentration.

Further, the method of using a zirconium-supporting cation exchange resin or a hydrated oxide of a rare earth element as an adsorbent, when used in wastewater containing fluorine and arsenic, which is the object of the present invention, adsorbs fluorine and arsenic together. Therefore, there is a disadvantage that the frequency of exchanging the adsorbent increases. For example, if the replacement time of the adsorbent is judged at the time when arsenic, which has a low regulation value, starts to leak, it has to be replaced while leaving the ability to adsorb fluorine, and the adsorbing ability cannot be fully exhibited.

The present invention has been made in view of the above points,
By combining a specific coagulation-sedimentation process, a fluorine adsorption treatment process, and an arsenic adsorption treatment process, the efficiency of the adsorption capacity of the fluorine adsorbent and the arsenic adsorbent can be increased, and a treatment method that can completely remove fluorine and arsenic is provided. Heading The present invention has been reached.

[0007]

Means for Solving the Problems That is, the present invention is to carry out coagulation-precipitation treatment of waste water containing fluorine and arsenic with aluminum sulfate or calcium chloride, then adsorption treatment with an aluminum-supporting resin, and then carrying zirconium. Is a method for treating fluorine- and arsenic-containing wastewater, in which adsorption treatment is performed using a type resin or a hydrous oxide of a rare earth element.

Examples of the aluminum-supported resin used in the present invention include an ion exchange resin adsorbing aluminum ions or a chelate resin adsorbing aluminum ions. As the cation exchange resin, styrene-divinylbenzene copolymer resin, vinyl chloride resin,
One type selected from the group of vinylidene chloride resin, acrylic resin and urea resin is used as a resin matrix, and a carboxylic acid group,
A cation exchange resin having an ion exchange group such as a sulfonic acid group is given, and as the chelate resin, an amino acid group, a thiourea group, a diethyldithiocarbamic acid group, a thiol group, an oxime group, and a resin base similar to the above are used. Examples thereof include chelate resins to which at least one selected from the group consisting of amidooxime group, imidooxime group, iminoacetic acid group, iminodiacetic acid group, iminopropionic acid group, and iminodipropionic acid group is added as a chelate-forming group.

As the zirconium-supporting resin used in the present invention, a cation exchange resin having the same ion exchange group in the same resin matrix as described above, or a chelate resin having a chelate forming group and zirconium oxychloride is used. Examples thereof include a resin obtained by adsorbing zirconium on an ion exchange resin or a chelate resin, or a granulated hydrated oxide of zirconium with a polymer material.

Examples of the rare earth element hydrous oxide used in the present invention include scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Rare earth element oxides or hydroxides of Hydrous oxides of these rare earth elements can be easily prepared, for example, by adding an alkaline solution to an aqueous solution of salts such as hydrochlorides, sulfates, and nitrates containing rare earth elements, and adjusting the pH, and these are used as they are. Alternatively, granulation with a polymer material can be used.

In the treatment method of the present invention, wastewater containing fluorine and arsenic is first subjected to coagulation-sedimentation treatment using aluminum sulfate or calcium chloride to reduce the fluorine concentration and arsenic concentration in the wastewater, thereby imposing a burden on the adsorbent. To reduce. The above coagulation-sedimentation treatment can be carried out by a conventional method. For example, after adjusting the waste water containing fluorine and arsenic to pH 5 to 8.5, preferably PH 6.5 to 7.5, aluminum sulfate or calcium chloride is added. After stirring for 5 to 30 minutes, preferably 10 to 20 minutes, a polymer flocculant may be added if necessary, and the produced water insoluble matter may be removed by static separation or filtration. The addition amount of aluminum sulfate or calcium chloride used in the coagulation-precipitation treatment is preferably 100 to 10,000 ppm with respect to the wastewater, and the polymer coagulant is polyacrylic amide, or an anion-modified, cation-modified, nonion-modified, etc. The polyacrylic amide type | system | group polymeric flocculant etc. which are obtained are mentioned. The addition amount is preferably 0.5 to 10.

Next, the coagulation-sedimentation-treated wastewater is adsorbed by an aluminum-supporting resin. For the adsorption treatment with the aluminum-type adsorption resin, any method can be adopted as long as the wastewater subjected to the coagulation-sedimentation treatment and the aluminum-supported resin are sufficiently contacted with each other. It can be carried out by a column system in which water flows in an upflow or a downflow, a batch system in which an aluminum-supported resin is added to wastewater, and the mixture is separated after mixing. By this treatment, fluorine can be removed from the waste water to usually 1 ppm or less, and since most of arsenic remains in the waste water, the aluminum-supported resin can adsorb only fluorine and fully exert its adsorption ability.

The wastewater which has been subjected to the adsorption treatment with the aluminum-supporting resin is then subjected to the adsorption treatment with the zirconium-supporting resin or the hydrous oxide of a rare earth element. Adsorption treatment with a zirconium-supporting resin or a hydrous oxide of a rare earth element is a column method if the waste water treated above and the zirconium-supporting resin or a rare earth element are in sufficient contact.
Any method of batch type can be adopted. By this treatment, arsenic can be removed from the wastewater up to 0.005 ppm or less, and the zirconium-supporting resin or the hydroxide of a rare earth element can adsorb only arsenic without being affected by fluorine. It can be fully demonstrated.

The treatment method of the present invention is preferably applied to wastewater containing fluorine and arsenic. As these wastewaters, for example, semiconductor manufacturing factory wastewater, hot spring water, or underground spring water used in geothermal power plants, etc. Treatment etc. are mentioned.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these as long as the gist thereof is not exceeded. Hereinafter, "%" represents "% by weight" and "BV" represents "l / l-R".

EXAMPLE 1 1000 ppm of sulfuric acid band was added to an aqueous solution containing 50 ppm of fluorine ion and 0.5 ppm of arsenic ion, and
After stirring for 0 minutes, 2 ppm of weak anion-modified polyacrylic amide was added and stirred, and the mixture was left standing for 5 minutes, and then solid-liquid separated by decantation. The obtained coagulation-sedimentation-treated water contained 15 ppm of fluorine ions and 0.
It was 5 ppm. Two glass columns having an inner diameter of 40 mmφ are arranged in series, and the first tower is filled with 100 ml of an aluminum-supported resin adsorbing 10 g of aluminum ions per 1000 ml of aminophosphoric acid type chelate resin, and 2
Weakly acidic ion exchange resin (Amberlite IRC
50) An apparatus filled with 100 ml of zirconium-supporting resin supporting 90 g of zirconium ions per 1000 ml was used, and the above-mentioned coagulation-sedimentation-treated water was added to SV10.
(BV / Hr), water was passed in a downward flow. Water flow is 600B
With V, 1 ppm of fluorine ion was detected in the treated water of the first tower, but arsenic ion of the treated water of the second tower was 0.005 ppm
It was below. When only the aluminum-supported resin in the first tower was regenerated and water was passed through, the treated water in the second tower contained 1 ppm of fluorine ions or 0.005 p of arsenic ions.
It was possible to pass 1,000 BV of water by the time pm was detected. Regeneration of aluminum-supported resin is 2N
-NaOH SV2 (BV / Hr), 3BV was passed through in a downward flow to elute, and then 20% aluminum sulfate aqueous solution 2B
V was added and stirred for 4 hours to adsorb aluminum.

Example 2 An iminodiacetic acid type chelate resin 1 containing an epoxy resin as a resin matrix was used in the first tower by using the same two-column type apparatus as in Example 1.
100 ml of aluminum-supporting resin having 12 g of aluminum adsorbed per 000 ml was filled, and 100 ml of zirconium-supporting resin prepared as follows was charged in the second column, and the aggregate-precipitation treatment was carried out in the same manner as in Example 1. Treated water containing 10 ppm of fluorine ions and 0.7 ppm of arsenic ions was subjected to water treatment at a water flow rate of SV5 (BV / Hr) and a downward flow. When the amount of water passed was 800 BV, 1 ppm of fluorine ion was detected in the treated water in the first tower, but the arsenic ion in the treated water in the second tower was 0.005 ppm or less. Only the aluminum-supported resin in the first tower was regenerated in the same manner as in Example 1, and water was further passed. When the treated water in the second tower contained 1 ppm of fluorine ions or 0.005 pp of arsenic ions.
It was possible to pass 1500 BV of water by the time it was detected. The zirconium-supporting resin is 1
A 0% zirconium oxychloride aqueous solution was neutralized with 2N-NaOH, the generated precipitate was filtered off, and dried at 50 ° C. for 48 hours.
g and 30% formalin 120 g were added, and this was added with nonylphenol 3 mol ethylene oxide adduct 0.1%
The resulting product was added dropwise to 2000 g of dichlorobenzene containing, while stirring, and subjected to a polycondensation reaction while dehydrating at 90 to 100 ° C. for 6 hours, and a granular product was used.

Example 3 To an aqueous solution containing 60 ppm of fluorine ion and 0.5 ppm of arsenic ion, 2000 ppm of calcium chloride was added and stirred for 10 minutes, then 3 ppm of medium anion-modified polyacrylic amide was added and stirred, and the mixture was allowed to stand for 5 minutes. After that, solid-liquid separation was performed by decantation. The obtained coagulation-sedimentation-treated water had a fluorine ion content of 20 ppm and an arsenic ion content of 0.5 ppm. The same two-column type apparatus as in Example 1 was used, and the aminophosphate-type chelate resin 10 was used for the first column.
100 ml of an aluminum-supported resin having 10 g of aluminum ions adsorbed per 100 ml was charged, and 100 ml of a hydrated oxide of cerium prepared as described below was charged in the second column, and the fluorine which had been subjected to the coagulation-precipitation treatment was added thereto. Treated water containing 15 ppm of ions and 0.1 ppm of arsenic ions was subjected to a downward flow of water at a water flow rate of SV10 (BV / Hr). When the amount of water passed was 900 BV, 1 ppm of fluorine ion was detected in the treated water in the first tower, but the arsenic ion in the treated water in the second tower was 0.005 ppm or less. Only the aluminum-supported resin in the first tower was regenerated in the same manner as in Example 1,
When water was further passed, 1,500 BV of water could be passed by the time when 1 ppm of fluorine ion or 0.005 ppm of arsenic ion was detected in the treated water in the second tower. As the hydrated oxide of cerium, an equimolar hydrogen peroxide solution is added to a 20% cerium chloride aqueous solution to adjust the pH.
After adjusting to 10, the mixture was heated to 85 ° C. and aged for 1 day and used.

Comparative Example 1 100 ml of an aluminum-supported resin having 10 g of aluminum ions adsorbed per 1000 ml of the same aminophosphoric acid type chelating resin as used in Example 1 was used to obtain an inner diameter of 40 mm.
In a column packed in a φ glass column, treated water containing 15 ppm of fluorine ions and 0.5 ppm of arsenic ions, which had been subjected to the coagulation-precipitation treatment in the same manner as in Example 1, was passed through at a water flow rate SV1.
The water was treated as 0 (BV / Hr) and downward flow. Water flow is 1
At 0 BV, arsenic ions will be 0.005 pp in the treated water.
m was started to be detected, and when water was passed therethrough, a high concentration of arsenic ion was released into the treated water.

Comparative Example 2 Zirconium-supporting resin 10 carrying 90 g of zirconium ions per 1000 ml of weakly acidic ion exchange resin (Amberlite IRC50) similar to that used in Example 1.
In a column filled with 0 ml of a glass column having an inner diameter of 40 mmφ, treated water containing 15 ppm of fluorine ions and 0.5 ppm of arsenic ions, which had been subjected to the coagulating sedimentation treatment in the same manner as in Example 1, was passed through at a water flow rate SV10 (BV / Hr). The water was treated by downward flow. When the water flow rate reached 50 BV, 0.005 ppm of arsenic ions began to be detected in the treated water, and 100
When BV water was passed, 1 ppm of fluorine ions began to be detected in the treated water, and when water was passed further, fluorine ions and arsenic ions flowed out into the treated water.

Comparative Example 3 Cerium hydrate oxide 100 similar to that used in Example 3
In a column filled with ml in a glass column having an inner diameter of 40 mmφ,
Fluoride ion 1 which was subjected to coagulation-precipitation treatment in the same manner as in Example 1
Treated water containing 5 ppm and 0.5 ppm of arsenic ion was subjected to water treatment at a water flow rate of SV5 (BV / Hr) and a downward flow. When the amount of water flow reaches 170 BV, 0.005 ppm of arsenic ion begins to be detected in the treated water, and 200 BV
When water was passed, 1 ppm of fluorine ions were detected, and when water was passed further, fluorine ions and arsenic ions flowed out into the treated water.

[0022]

As described above, the treatment method of the present invention is a combination of a specific coagulation-sedimentation treatment, a fluorine adsorption treatment step, and an arsenic adsorption treatment step. By effectively using
It has excellent effects such as complete removal of fluorine and arsenic from the wastewater, less frequent regeneration of each adsorbent, and treatment of a large amount of wastewater.

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Claims (1)

[Claims] 1. A wastewater containing fluorine and arsenic is coagulated and precipitated with aluminum sulfate or calcium chloride, adsorbed with an aluminum-supported resin, and then zirconium-supported resin or hydrated oxidation of a rare earth element. A method for treating wastewater containing fluorine and arsenic, which comprises performing adsorption treatment using a substance.