KR102115155B1 - Remover of fluoride ion and treatment method for waste water comprising fluoride ion using the same - Google Patents

Abstract

The present invention relates to a fluorine removal technology, and more particularly, to a dissolved fluorine ion remover for removing fluorine ions contained in wastewater and a method for treating fluorine-containing wastewater using the same. According to one embodiment of the present invention, fluorine can be efficiently removed below a fluorine-containing wastewater discharge limit by mixing components capable of forming a very stable insoluble complex compound with fluorine. In addition, according to an embodiment of the present invention, a limestone exhibiting weak alkalinity as a main component and strong alkali-calcined lime are mixed at a certain ratio to prevent a phenomenon in which the pH value increases rapidly when injecting a drug, and thus undergoes a separate pH adjustment process. Even if it can be treated within the waste water discharge allowance.

Description

Fluoride ion remover and treatment method of fluorine-containing wastewater using the same {REMOVER OF FLUORIDE ION AND TREATMENT METHOD FOR WASTE WATER COMPRISING FLUORIDE ION USING THE SAME}

The present invention relates to a fluorine removal technology, and more particularly, to a dissolved fluorine ion remover for removing fluorine ions contained in wastewater and a method for treating fluorine-containing wastewater using the same.

Fluorine-containing wastewater is discharged from many fields such as semiconductor, glass manufacturing, aluminum and iron manufacturing processes, electroplating processes, LCDs and electronics. Fluoride is basically a toxic substance that inhibits enzyme activity, slows white blood cell activity, and damages the immune system. Therefore, even at low concentrations, long-term ingestion is a concern for health problems.

On the other hand, fluoride regulates the allowable limit of 3 mg / L for wastewater discharged to clean areas and 15 mg / L or less for wastewater discharged to non-clean areas. However, the flow of fluoride treatment differs depending on the amount generated and the concentration, and if it is expected that the concentration of fluoride will be strengthened in the future, it will be difficult to meet the emission limit. Therefore, it is necessary to find suitable treatment conditions and applicable fluorine ion removers and to provide measures to show optimum treatment efficiency.

In general, as a method of removing fluorine contained in wastewater generated in the semiconductor or display industry, a method in which fluorine ions in the wastewater are insoluble and then removed by solid-liquid separation has been used.

However, this method was difficult to remove fluoride below the fluorine-containing wastewater limit of 15 mg / L due to poor fluoride treatment efficiency. Therefore, there is a need to develop a new fluorine treatment agent that can stably remove fluorine to 10 mg / L or less more efficiently.

In addition, when slaked lime [Ca (OH) ₂ ] is mainly used as a fluorine treatment agent, it is a very strong alkali component, so even when a small amount of chemical is added, the pH rises rapidly and shows alkalinity. In order to meet the 8.5, there is a problem in that it is necessary to go through the process of adjusting the pH by adding a separate acid in the future, and there is a problem in that the cost of the drug is additionally caused.

Republic of Korea Patent Publication No. 10-2009-0109962 (2009.10.21, fluorine ions and cyanide compounds and free cyanide remover and wastewater treatment method using the same)

The present invention is a fluorine ion remover of a new composition capable of effectively removing fluorine below a fluorine-containing wastewater discharge limit by mixing components capable of forming a very stable insoluble complex compound with fluorine and a fluorine-containing wastewater using the same. It is intended to provide a treatment method.

The present invention also prevents the phenomenon of rapid increase in the pH value when injecting chemicals by mixing limestone, which has weak alkalinity as a main component, and strong alkaline slaked lime at a constant rate, so that it is processed within the discharged allowance without requiring a separate pH adjustment process. It is intended to provide a method for treating a fluorine-containing wastewater using the fluorine ion remover of the new composition.

According to one aspect of the invention, there is provided a fluorine removal agent.

The fluorine removal agent according to an embodiment of the present invention may include 5% to 40% by weight of limestone (CaCO3) and 1% to 20% by weight of slaked lime (Ca (OH) 2).

According to one embodiment, the fluorine removal agent may further include less than 1% by weight of strontium carbonate (SrCO3).

According to one embodiment, the fluorine removal agent may further include at least one of potassium dihydrogen phosphate (KH2PO4 ') and potassium monohydrogen phosphate (K2HPO4) less than 1% by weight.

According to another aspect of the present invention, there is provided a method for treating fluorine-containing wastewater using a fluorine removing agent.

A method of treating fluorine-containing wastewater using a fluorine removing agent according to an embodiment of the present invention comprises the steps of adding a first fluorine treatment agent in which limestone and slaked lime are mixed to a fluorine-containing wastewater in a reaction tank and the fluorine-containing wastewater is After the reaction in the reaction tank may include the step of introducing a second fluorine treatment agent containing an aluminum salt in the precipitation reaction tank is discharged.

According to one embodiment, the primary fluorine remover may include 5% to 40% by weight of limestone (CaCO3) and 1% to 20% by weight of slaked lime (Ca (OH) 2).

According to one embodiment, the primary fluorine remover may further include less than 1% by weight of strontium carbonate (SrCO3).

According to one embodiment, the primary fluorine remover may further include at least one of potassium dihydrogen phosphate (KH2PO4 ') and potassium monohydrogen phosphate (K2HPO4) less than 1% by weight.

According to one embodiment, the secondary fluorine removal agent has a content of at least one aluminum salt of PAC, Alum, AlCl3 and PASS of 5% to 20% by weight, potassium dihydrogen phosphate (KH2PO4 ') and potassium monohydrogen phosphate (K2HPO4 ) Less than 1% by weight.

According to one embodiment of the present invention, fluorine can be efficiently removed below a fluorine-containing wastewater discharge limit by mixing components capable of forming a very stable insoluble complex compound with fluorine.

In addition, according to an embodiment of the present invention, a limestone exhibiting weak alkalinity as a main component and strong alkali-calcined lime are mixed at a certain ratio to prevent a phenomenon in which the pH value increases rapidly when injecting a drug, and thus undergoes a separate pH adjustment process. Even if it can be treated within the wastewater discharge limit.

1 is a process diagram for explaining a fluorine-containing wastewater treatment method according to an embodiment of the present invention.
2 is a schematic view for explaining a treatment process for each reaction tank of fluorine-containing wastewater according to an embodiment of the present invention.
FIG. 3 is a view for explaining a production process and crystal structure of an insoluble fluorine complex according to an embodiment of the present invention.

Terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, when a part “includes” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated. Since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to what is shown. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

Hereinafter, a preferred embodiment of the fluorine ion removing agent according to the present invention and a method for treating fluorine-containing wastewater using the same will be described in detail with reference to the accompanying drawings, and in describing with reference to the accompanying drawings, the same or corresponding components The same reference numerals are given and duplicate descriptions thereof will be omitted.

1 is a process diagram for explaining a fluorine-containing wastewater treatment method according to an embodiment of the present invention.

Referring to Figure 1, the treatment process for the fluorine-containing wastewater according to the present invention, first, the high-concentration fluorine-containing wastewater collected in the water collection tank is composed of limestone (CaCO3) as a main component in the reaction tank, and slaked lime (Ca (OH) 2) in a certain ratio. A certain amount of the first fluorine treatment agent is added, and aluminum salt (at least one of PAC, Alum, AlCl3, and PASS) is mainly used in the coagulation tank, potassium dihydrogen phosphate (KH ₂ PO ₄ ) or potassium monohydrogen phosphate (K ₂ HPO _A certain amount of the second fluorine treatment agent containing ₄ ) is added. Thereafter, the insoluble fluorine complex is precipitated in the precipitation tank so that the residual fluorine is 15 mg / L or less.

2 is a schematic view for explaining a treatment process for each reaction tank of fluorine-containing wastewater according to an embodiment of the present invention.

 Referring to Figure 2, the fluorine-containing wastewater can be used as the first composition as a fluorine treatment agent.

The composition of the first fluorine treatment agent:

CaCO ₃  + Ca (OH) ₂  + SrCO ₃  + K ₂ HPO ₄  or KH ₂ PO ₄

Here, CaCO ₃ is preferably 5% by weight to 40% by weight. If the CaCO ₃ is less than 5% by weight, the efficiency of fluorine treatment is very low, and when it exceeds 40% by weight, it is inconvenient to transport and manage due to excessive sediment, and a problem of increasing sludge generation occurs.

Ca (OH) ₂ is preferably 1 to 20% by weight. When Ca (OH) ₂ is less than 1% by weight, the pH does not rise, resulting in problems in pH management and poor fluoride treatment efficiency. On the other hand, when Ca (OH) ₂ exceeds 20% by weight, a separate pH must be adjusted and managed due to excessive rise in pH, and excessive sludge is generated.

SrCO ₃ is preferably less than 1% by weight. When SrCO ₃ is 1% by weight or more, the treatment cost is excessively increased due to the increase in drug costs.

Preferably, at least one of K ₂ HPO ₄ and KH ₂ PO ₄ is less than 1% by weight. If at least one of K ₂ HPO ₄ and KH ₂ PO ₄ is 1% by weight or more, another wastewater treatment problem due to overdosing of phosphorus (P) may occur.

The first fluorine treatment agent forms a very stable insoluble fluorine complex with fluorine as shown in the following reaction formula.

[Scheme 1]

CaF₂(s)Ca ²⁺ + 2F ^-

CaF ₂ (s)

Ca₁₀(PO₄)₆F₂(s) ^{_{Ca 2+ + PO 4 3- (HPO}} 4 2-, H2PO 4 -) + 2F -

Ca ₁₀ (PO ₄ ) ₆ F ₂ (s)

Ca_xSr_10-x(PO₄)₆F₂(s) ^{_{Ca 2+ + Sr 2+ + PO 4}} 3- (HPO 4 2-, H2PO 4 -) + 2F -

Ca _x Sr _10-x (PO ₄ ) ₆ F ₂ (s)

In addition, the following composition may be used as the second fluorine treatment agent.

The composition of the 2nd fluorine treatment agent:

PAC, Alum, AlCl ₃ , PASS + K ₂ HPO ₄ , KH ₂ PO ₄

Here, the content of at least one aluminum salt of PAC, Alum, AlCl3 and PASS is preferably 5% to 20% by weight. When the content of at least one aluminum salt of PAC, Alum, AlCl3 and PASS is less than 5% by weight, the efficiency of fluorine treatment is very low, and when it exceeds 20% by weight, transportation and management of high-concentration chemicals is inconvenient and the problem of sludge generation increases. Occurs.

Preferably, at least one of K ₂ HPO ₄ and KH ₂ PO ₄ is less than 1% by weight. If at least one of K ₂ HPO ₄ and KH ₂ PO ₄ is 1% by weight or more, another wastewater treatment problem due to overdosing of phosphorus (P) may occur.

The second fluorine treatment agent forms a very stable insoluble fluorine complex with fluorine as shown in the following reaction formula.

[Scheme 2]

Al(OH)₃F(s) Al ³⁺ + 3OH- + 2F-

Al (OH) ₃ F (s)

Ca₁₀(PO₄)₆F₂(s)Ca ²⁺ + PO ₄ ^3- (HPO ₄ ^2- , H ₂ PO ^4- ) + 2F-

Ca ₁₀ (PO ₄ ) ₆ F ₂ (s)

In the coagulation tank, fluorine ions are adsorbed and precipitated and removed when aluminum hydroxide precipitates. Here, since PAC or Alum exhibits strong acidity, Ca ²⁺ is generated by dissolving unreacted CaCO ₃ or Ca (OH) ₂ injected during the first treatment when injecting the chemical for the second treatment. Ca ²⁺ is precipitated by forming a very stable insoluble complex with HPO ₄ ^2- , H ₂ PO ^4- and fluorine, enabling efficient removal of residual fluorine up to 10 mg / L or less.

FIG. 3 is a view for explaining a production process and crystal structure of an insoluble fluorine complex according to an embodiment of the present invention.

Referring to FIG. 3, the formation and crystal structure of Ca ₁₀ (PO ₄ ) ₆ F _{2 which} is an insoluble fluorine complex is indicated.

The present invention will be described in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the present invention and are not limited to these.

 [Example 1]

The first fluorine treatment agent according to the present invention is largely composed of four compositions, first, the content of quicklime (CaCO ₃ ) is 1, 15, 25, 40% by weight, and the content of slaked lime (Ca (OH) ₂ ) Is 5, 7, 10, 15, 20, 25, 30, 40% by weight, the content of SrCO ₃ is 0.5, 1.5, 1.5% by weight, and at least one of K ₂ HPO ₄ and KH ₂ PO ₄ is 0.5 , 1.0, 1.5 wt%, mixed in various composition ratios to prepare the first fluorine treatment agent, and then injected into 3,000 ppm of the semiconductor wastewater containing 360.8 ppm of fluorine ions, sufficiently stirred and precipitated to measure the fluorine removal efficiency. It is shown in Table 1 below.

Fluorine removal efficiency measurement result according to the composition of the first fluorine treatment agent Example 1 1st treatment (injection rate 3,000ppm) Composition ratio (wt%) Treatment result CaCO ₃ Ca (OH) ₂ SrCO ₃ K ₂ HPO ₄ F ^- (ppm) pH S-1 - 30 - - 42.2 10.21 S-2 25 - - - 43.8 5.83 S-3 One 25 - - 51.7 9.79 S-4 5 20 - - 48.4 9.03 S-5 15 15 - - 33.9 8.32 S-6 25 10 - - 21.5 7.53 S-7 40 5 - - 20.9 7.01 S-8 25 7 - - 21.9 7.38 S-9 25 7 - - 21.9 7.39 S-10 25 7 - - 21.8 7.38 S-11 25 30 - - 19.5 10.73 S-12 25 40 - - 18.0 11.6 S-13 25 7 0.5 0.5 17.0 7.29 S-14 25 7 1.0 1.0 16.1 7.30 S-15 25 7 1.5 1.5 15.9 7.31 S-16 25 7 0.5 0.5 17.5 7.29 S-17 25 7 0.5 0.5 17.0 7.29

Considering the results of the above experiments, considering that Korea's emission limit values of fluorine (15 ppm) and pH (6.5 to 8.5) are considered, Examples S-13 to S-17 are very excellent as primary treatment results. I could confirm.

[Example 2]

In Example 1, the second fluorine treatment agent according to the present invention was added to the first treated effluent. The second fluorine treatment agent is largely composed of two compositional materials. First, at least one content of PAC, Alum, AlCl ₃ and PASS is fixed at 12% by weight, and at least one of K ₂ HPO ₄ and KH ₂ PO ₄ is fixed. After mixing 0.5, 1.0, and 1.5% by weight in various composition ratios to prepare a second fluorine treatment agent, 700 ppm is injected into the semiconductor wastewater containing the primary treated fluoride ion in Example 1, stirred sufficiently, and precipitated to remove fluoride. The results of measuring the efficiency are shown in Table 2 below.

Fluorine removal efficiency measurement result according to the composition of the second fluorine treatment agent Example 2 Primary treatment
(Injection rate 3000ppm) Secondary treatment
(Injection rate 700ppm) Before treatment
F ^-
(ppm) After treatment
F ^- (ppm) Sludge
Generation
(g / L) Treatment result Composition ratio (wt%) After treatment
pH F ^- (ppm) pH PAC K ₂ HPO ₄ S-1 42.2 10.21 12 - 8.90 360.8 21.6 0.6342 S-2 43.8 5.83 12 - 4.35 360.8 25.9 0.6031 S-3 51.7 9.79 12 - 8.33 360.8 37.4 0.6217 S-4 48.4 9.03 12 - 7.81 360.8 37.9 0.6105 S-5 33.9 8.32 12 - 7.35 360.8 18.9 0.6310 S-6 21.5 7.53 12 - 6.69 360.8 10.6 0.6398 S-7 20.9 7.01 12 - 5.99 360.8 9.6 0.6601 S-8 21.9 7.38 12 - 6.28 360.8 10.5 0.6348 S-9 21.9 7.39 12 1.0 6.25 360.8 8.7 0.6350 S-10 21.8 7.38 12 1.5 6.23 360.8 8.6 0.6355 S-11 19.5 10.73 12 - 9.27 360.8 14.3 1.1137 S-12 18.0 11.6 12 - 10.13 360.8 13.9 1.3679 S-13 17.0 7.29 12 1.0 6.17 360.8 7.4 0.6352 S-14 16.1 7.30 12 1.0 6.17 360.8 7.0 0.6353 S-15 15.9 7.31 12 1.0 6.18 360.8 7.0 0.6355 S-16 17.5 7.29 12 1.5 6.14 360.8 7.1 0.6356 S-17 17.0 7.29 12 0.5 6.21 360.8 6.9 0.6349

Considering the results of the above experiments, considering the emission standards of Korea and the amount of sludge generated in fluorine (15 ppm) and pH (6.5 to 8.5), Examples S-13 to S-17 are secondary treatment results. It was confirmed that it was very excellent. [Comparative example]

The content of at least one of the first fluorine treatment agent and PAC, Alum, AlCl ₃ and PASS in which the content of quicklime (CaCO ₃ ) is 25% by weight and the content of slaked lime (Ca (OH) ₂ ) is 7% by weight Is fixed to 12% by weight, and the present invention using a second fluorine treatment agent containing at least one of K ₂ HPO ₄ and KH ₂ PO ₄ in an amount of less than 1.0% by weight, and conventional slaked lime [Ca (OH) 2] 1 After the secondary treatment, the results of measuring the fluorine removal efficiency by injecting the existing product secondaryly treated with aluminum salts such as PAC, Alum, AlCl3, and sufficiently stirring and sedimenting are shown in Table 3 below.

Fluorine removal efficiency measurement results of the present invention and existing products Raw waste water
F ^- (ppm)  division Fluoride treatment agent
Injection (ppm) 1st treatment result PAC injection
(ppm) Second treatment result pH F ^- (ppm) pH F ^- (ppm) pH adjustment 360.8 Original product 3,000 10.21 42.2 700 8.9 26.6 Hydrochloric acid 0.30mL / L The present invention
CaCO ₃ (25%) + Ca (OH) ₂ (7%) 3,000 7.66 21.4 700  6.76 10.0 Nothing

As a result of the first treatment, the pH of the present invention was almost neutral at 7.66 compared to the existing product using only slaked lime, and the fluorine content was almost 1/2 times as high as 21.4 ppm. As a result of the second treatment, the present invention had a pH of 6.76. , The fluorine content of 10.0 ppm satisfied the discharged water discharge limit, but the existing product with the same capacity had a pH of 8.9 (after pH adjustment using hydrochloric acid) and a fluorine content of 26.6 ppm. Not satisfied. Therefore, the present invention has a very excellent fluorine treatment effect at the same capacity compared to the existing invention, and prevents a phenomenon in which the pH value of the existing product increases rapidly, so that the discharged water discharge allowance can be satisfied without a separate pH adjustment process.

As described above, preferred embodiments of the present invention have been described, but those skilled in the art can add, change, delete or add components within the scope of the present invention as described in the claims. By this, the present invention can be variously modified and changed, and it will be said that it is also included within the scope of the present invention.

Claims (8)

delete delete delete In the treatment method of wastewater containing fluorine ions,
Introducing a primary fluorine treatment agent in which limestone and slaked lime are mixed at a constant ratio to the fluorine-containing wastewater in the reaction tank; And
The fluorine-containing waste water is discharged after the reaction in the reaction tank and the step of introducing a second fluorine treatment agent containing an aluminum salt in the precipitation reaction tank,
The first fluorine treatment agent
Limestone (CaCO3) 5 wt% to 40 wt%, and slaked lime (Ca (OH) 2) 1 wt% to 20 wt%,
Further comprising less than 1% by weight of strontium carbonate (SrCO3),
At least one of potassium dihydrogen phosphate (KH2PO4) and potassium monohydrogen phosphate (K2HPO4) further comprises less than 1% by weight,
The second fluorine treatment agent
5 to 20% by weight of aluminum salt of at least one of PAC, Alum, AlCl3 and PASS,
It comprises at least one of potassium dihydrogen phosphate (KH2PO4) and potassium monohydrogen phosphate (K2HPO4) in an amount of less than 1% by weight,
In the second fluorine treatment agent, fluorine ions are adsorbed to the aluminum salt to remove residual fluorine from wastewater containing fluorine ions treated first in the reaction tank.
Method for treating wastewater containing fluoride ions. delete delete delete delete

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