KR20170036575A - Treatment method of wastewater containing 1,4-dioxane - Google Patents

Abstract

The present invention relates to a treatment method of wastewater containing 1,4-dioxane, which comprises the following steps: firstly treating the wastewater containing 1,4-dioxane and organic materials by using a membrane bioreactor (MBR); and secondly treating by putting the firstly treated petrochemical plant wastewater into a reaction tank which contains a transition metal catalyst and by injecting ozone gas into the reaction tank.

Description

TECHNICAL FIELD The present invention relates to a method for treating 1,4-dioxane-containing wastewater,

The present invention relates to a method for treating 1,4-dioxane-containing wastewater. More particularly, the present invention relates to a method for treating 1,4-dioxane-containing wastewater which is excellent in the removal efficiency of 1,4-dioxane and organic matter.

1,4-Dioxane is widely used as industrial solvents and stabilizers and is produced as a by-product in the polyester manufacturing process. The US EPA and the International Cancer Institute (IARC) classify 1,4-dioxane as a carcinogenic substance. Considering the environmental and human health hazards, 1,4-dioxane present in petrochemical wastewater is required to be removed, but 1,4-dioxane has a boiling point of 101.1 ° C which is similar to water and has high solubility in water Separate treatment to remove 1,4-dioxane is required because it can not be removed well by general treatment methods such as stripping or activated carbon adsorption.

Conventional processes for treating 1,4-dioxane include aerobic biological treatment using an advanced oxidation process (AOP) using a photocatalyst, ozone, hydrogen peroxide, ultrasonic waves, and 1,4-dioxane decomposing bacteria or using activated sludge .

The advanced oxidation process consists of various combinations of ozone / photocatalyst, photocatalyst / hydrogen peroxide, ozone / hydrogen peroxide, ozone / ultrasonic wave, etc., and the treatment efficiency is high, but the drug cost and energy cost are excessively high. In addition, when a photocatalyst is used, there is a problem that the UV tube must be periodically cleaned in order to suppress the deterioration of the treatment efficiency due to the increase of contamination on the surface of the UV tube due to the generation of waste. In addition, in the case of wastewater containing a high concentration of 1,4-dioxane, power consumption is high because ozone is required at a high concentration, and in the case of an advanced oxidation process using ozone / hydrogen peroxide, However, a subsequent process for decomposing or removing hydrogen peroxide after wastewater treatment is required, and there is a problem in that there is a limit to the removal of organic matter (COD) contained in wastewater.

Although there is a method of using 1,4-dioxane-degrading bacteria as a biological treatment method, there is no case where it is applied on the spot, and since a specific decomposing bacterium is expressed, it is difficult to operate and manage.

Related Background Art is disclosed in Korean Patent Publication No. 2010-0096694.

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a process for producing 1,4-dioxane, which is excellent in the removal efficiency of 1,4-dioxane and organic matter, has low energy consumption and maintenance cost, does not generate waste, Dioxane-containing waste water.

In one aspect, the present invention relates to a process for treating wastewater containing 1,4-dioxane and organic matter by a primary treatment using a membrane filtration reactor (Membrane BioReactor, MBR); And a step of injecting the primary treated petrochemical wastewater into a reaction tank containing a transition metal catalyst and injecting ozone gas to perform a secondary treatment, thereby providing a method for treating 1,4-dioxane-containing wastewater.

In this case, the transition metal catalyst may be a manganese sulfate (MnSO _4), zinc sulfate heptahydrate _{(ZnSO 4 · 7H 2 O)} , nickel sulfate, hexahydrate (NiSO _{4 ·} 6H ₂ O), or a combination thereof, wherein The concentration of the transition metal catalyst in the reaction tank is preferably about 0.5 to 2 mg / L.

Meanwhile, the biofilm reactor may include a bioreactor including a breathable microorganism and a filtration membrane unit.

For example, the biofiltration reactor has an F / M ratio of about 0.01 to about 0.03 kg BOD / kg MLSSday, a BOD volume load of about 0.15 to about 0.20 kg / m ³ / day, a MLSS (Mixed Liquor Suspended Solids) of about 7,500 to 10,000 mg / L, and the residence time (HRT) of the biofiltration reactor may be about 24 to 48 hours.

On the other hand, in the secondary treatment step, it is preferable that the ozone gas is injected so that the dissolved ozone concentration in the reaction tank is 1 to 10 mg / L.

According to the wastewater treatment method of the present invention, the removal rate of 1,4-dioxane can be 90% or more and the removal rate of organic matter can be 90% or more.

According to the method for treating wastewater containing 1,4-dioxane according to the present invention, 1,4-dioxane and organic substances contained in wastewater can be removed at a high removal rate of 90% or more.

In addition, the method for treating 1,4-dioxane-containing wastewater according to the present invention requires less subsequent steps since a smaller amount of ozone is injected and less energy is used and no waste is generated as compared with the conventional method using hydrogen peroxide or a photocatalyst There is an advantage that it does not.

1 is a flow chart of a method for treating wastewater containing 1,4-dioxane according to the present invention.
2 is a schematic view for explaining a method for treating wastewater containing 1,4-dioxane according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Fig. 1 shows a flowchart of a method for treating wastewater containing 1,4-dioxane according to the present invention. As shown in FIG. 1, the wastewater treatment method of the present invention is characterized by carrying out a two-step treatment consisting of a treatment step using a membrane filter (Membrane BioReactor, MBR) and a treatment step using a transition metal catalyst and ozone . Specifically, the method for treating 1,4-dioxane-containing wastewater according to the present invention comprises the steps of passing primary wastewater containing 1,4-dioxane and organic matter through a membrane filtration reactor (Membrane BioReactor, MBR) And a step of injecting the primary treated petrochemical wastewater into a reaction tank containing a transition metal catalyst and injecting ozone gas to secondary treatment.

As described above, there is a problem in that, in the conventional wastewater treatment method of either biological treatment or chemical treatment, the removal efficiency of one of 1,4-dioxane and organic matter in the wastewater is inferior. In addition, the conventional chemical treatment methods used for 1,4-dioxane decomposition have problems such as high power consumption and waste generation.

In order to solve the above problems, the inventors of the present invention have conducted extensive research and have found that, after a biological treatment step (primary treatment) using MBR is carried out, a reaction tank containing a transition metal catalyst including Mn, Zn, Dioxane can be improved by up to 90% or more without post-treatment due to the generation of waste when performing the secondary treatment of oxidizing 1,4-dioxane by injecting ozone gas , Thereby completing the present invention.

2 shows a schematic diagram of a method for treating 1,4-dioxane-containing wastewater according to the present invention. Below. Each step of the wastewater treatment method of the present invention will be described in more detail with reference to Fig.

First, the wastewater containing 1,4-dioxane and organic matter is introduced into a Membrane BioReactor (MBR) 100.

As the biofiltration reactor 100 used in the present invention, biofiltration reactors generally used in the art can be used without limitation, and are not particularly limited.

For example, the biofiltration reactor 100 may include a bioreactor 110 and a filtration membrane unit 120. The bioreactor 110 may include an aeration unit 130 for aeration of wastewater, May be included.

The bioreactor 110 includes an organic substance contained in wastewater and an aerobic microorganism for decomposing 1,4-dioxane. At this time, the concentration of aerobic microorganisms in the bioreactor 110, MLSS (Mixed Liquor Suspended Solids), may be 7,000 mg / L or more, preferably 7,500 to 10,000 mg / L. By containing the aerobic microorganisms at such a high concentration, the removal efficiency of the organic substances and 1,4-dioxane contained in the wastewater can be further improved.

Meanwhile, the biofiltration reactor may have an F / M ratio, preferably about 0.01 to 0.03 kg BOD / kg of MSSday. The F / M ratio is relatively low as compared with the F / M ratio in the conventional activated sludge process. When the F / M ratio is in the above range, it is considered that the aerobic microorganisms in the biofilm reactor can provide an environment in which 1,4-dioxane can be used as food.

In addition, the BOD volume load of the biofiltration reactor 100 may be about 0.15 to 0.20 kg / m ³ / day, but is not limited thereto.

Meanwhile, the time (HRT) during which the wastewater stays in the biofiltration reactor 100 can be appropriately adjusted according to the concentration of the organic matter and 1,4-dioxane contained in the wastewater, the throughput, etc., and is not particularly limited. For example, the residence time (HRT) may be about 24 to 48 hours.

The wastewater (primary treatment water) subjected to the primary treatment by the microorganisms in the biological reaction tank is filtered by the filtration membrane unit 120, and then discharged to the reaction tank 200 for the secondary treatment. At this time, as the filtration membrane unit 120, various filtration membranes applicable to the biofiltration reactor in the related art can be used without limitation, and the material and kind thereof are not particularly limited. Specifically, the filtration membrane unit 120 may be a hollow fiber membrane, but is not limited thereto.

Next, the primary treatment water is introduced into the reaction tank 200 containing the transition metal catalyst, and the secondary treatment is performed by injecting ozone gas.

The transition metal catalyst is a catalyst containing transition metals such as Mn, Zn, Ni and the like. Specifically, manganese sulfate (MnSO ₄ ), zinc sulfate heptahydrate (ZnSO ₄ .7H ₂ O), nickel sulfate · Hexahydrate (NiSO ₄ · 6H ₂ O) or a combination thereof.

When the ozone gas is injected into the reaction vessel containing the transition metal catalyst as described above, OH radical generation is promoted with only a small amount of catalyst, thereby accelerating the rate of 1,4-dioxane decomposition reaction. As a result, compared to the prior art, the removal efficiency and the removal rate of 1,4-dioxane are formed.

The concentration of the transition metal catalyst in the reaction tank may vary depending on the amount of wastewater to be treated and the concentration of 1,4-dioxane contained in the wastewater, but may be, for example, about 0.5 to 2 mg / L . When the transition metal catalyst concentration satisfies the above range, both efficiency and economy are excellent. In the secondary treatment step, the ozone gas is preferably injected so that the dissolved ozone concentration in the reaction tank is 1 to 10 mg / L, but not limited thereto.

According to the treatment method of the present invention, 1,4-dioxane and organic matter (COD) can be removed with high efficiency. Specifically, in the case of treated water subjected to the secondary treatment, the 1,4-dioxane removal rate and the organic matter removal rate are both 90% or more.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

Example  One

The 1,4-dioxane-containing wastewater (1,4-dioxane 70 mg / L, COD _cr 955 mg / L) was added to the MBR for primary treatment. At this time, the MBR reactor capacity was 7L, the operating conditions were BOD volume load of 0.164 kg / m ³ / day, MLSS of 7,500 ~ 10,000 mg / L and F / M ratio of 0.02 kg BOD / kgML SSday. As the filtration membrane unit, a hollow organic membrane was used.

300 mL of the treated water treated first by MBR and 1 mg / L of manganese sulfate (MnSO ₄ ) as a transition metal catalyst were added to the reaction tank and the ozone gas generated by the ozonizer was injected into the reaction tank for secondary treatment. The concentration of dissolved ozone in the reaction tank was 8 mg / L. The content of 1,4-dioxane and the content of COD in the secondary treatment water were measured using a gas chromatography mass spectrometer (GC / MS) and a chemical oxygen demand analysis kit, respectively, and 1,4-dioxane and organic matter ) Was measured. The measurement results are shown in Table 1 below.

Example  2

Except that zinc sulfate heptahydrate (ZnSO ₄ 7H ₂ O) was used in place of manganese sulfate (MnSO ₄ ) as a transition metal catalyst, the same procedure as in Example 1 was conducted to treat wastewater and 1,4-dioxane and organic matter ) Was measured. The measurement results are shown in Table 1 below.

Example  3

Dioxane and organic matter (COD) were treated in the same manner as in Example 1 except that nickel sulfate hexahydrate (NiSO ₄ 6H ₂ O) was used instead of manganese sulfate (MnSO ₄ ) as a transition metal catalyst. Was measured. The measurement results are shown in Table 1 below.

Comparative Example  One

The wastewater was treated in the same manner as in Example 1 except that the transition metal catalyst was not used, and the removal rate of 1,4-dioxane and organic matter (COD) was measured. The measurement results are shown in Table 1 below.

Comparative Example  2

Dioxane-containing wastewater (1,4-dioxane 70 mg / L, COD _cr 955 mg / L) was added to the MBR. At this time, the capacity and operating conditions of the MBR tank are the same as those of the first embodiment. Then, the content of 1,4-dioxane and the content of COD in the treated water in the MBR were measured using a gas chromatograph mass spectrometer and a chemical oxygen demand analysis kit, respectively, and 1,4-dioxane and organic matter (COD ) Was measured. The measurement results are shown in Table 1 below.

Comparative Example  3

300 mL of 1,4-dioxane-containing wastewater (1,4-dioxane 70 mg / L, COD _cr 955 mg / L) was placed in the reaction tank and treated with ozone gas generated by an ozone generator. The concentration of dissolved ozone in the reaction tank was 8 mg / L. Then, the 1,4-dioxane content and the COD content in the treated water treated in the reaction tank were measured using a GC / MS and a chemical oxygen demand analysis kit, respectively, and 1,4- The removal rates of dioxane and organic matter (COD) were measured. The measurement results are shown in Table 1 below.

division Processing method 1,4-dioxane
Removal rate (%) Organic matter (COD)
Removal rate (%) Example 1 MBR + ozone / transition metal (Mn) catalyst process 95 93 Example 2 MBR + ozone / transition metal (Zn) catalyst process 94 93 Example 3 MBR + ozone / transition metal (Ni) catalyst process 94 93 Comparative Example 1 MBR + ozone oxidation process 89 92 Comparative Example 2 MBR single process 70 90 Comparative Example 3 Ozone oxidation only process 4 9

As shown in Table 1, in Examples 1 to 3 in which the MBR process and the ozone / transition metal catalytic oxidation process were carried out, the removal ratios of 1,4-dioxane and organic matter were all higher than 90% , And in Comparative Examples 1 to 3, the removal rates of 1,4-dioxane and organic substances were lower than those of Examples 1 to 3.

100: Biofilter Reactor
110: Bioreactor
120: Filtration unit
200: transition metal catalyst / ozone reactor

Claims (10)

Primary treatment of wastewater containing 1,4-dioxane and organic matter using a membrane filtration reactor (Membrane BioReactor, MBR); And
A method for treating 1,4-dioxane-containing wastewater, comprising the step of introducing the primary treated petrochemical wastewater into a reaction tank containing a transition metal catalyst and injecting ozone gas for secondary treatment. The method according to claim 1,
Wherein the transition metal catalyst is selected from the group consisting of manganese sulfate (MnSO ₄ ), zinc sulfate heptahydrate (ZnSO ₄ 7H ₂ O), nickel sulfate hexahydrate (NiSO ₄ 6H ₂ O) or a combination thereof . The method according to claim 1,
Wherein the biofiltration reactor comprises a bioreactor including a breathable microorganism and a filtration membrane unit. The method according to claim 1,
Wherein the biofiltration reactor has an F / M ratio of 0.01 to 0.03 kg BOD / kgMLSSday. The method according to claim 1,
Wherein the biofiltration reactor has a BOD volume load of 0.15 to 0.20 kg / m ³ / day. The method according to claim 1,
Wherein the biofiltration reactor is a method for treating wastewater containing 1,4-dioxane having MLSS (Mixed Liquor Suspended Solids) of 7,500 to 10,000 mg / L. The method according to claim 1,
Wherein the biofiltration reactor has a retention time (HRT) of 24 to 48 hours. The method according to claim 1,
Wherein the concentration of the transition metal catalyst in the reaction tank is 0.5 to 2 mg / L. The method according to claim 1,
Wherein in the secondary treatment step, the ozone gas is injected so that the dissolved ozone concentration in the reaction tank is 1 to 10 mg / L. The method according to claim 1,
A process for treating 1,4-dioxane-containing wastewater having a 1,4-dioxane removal rate of 90% or more and an organic matter removal rate of 90% or more.

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