KR101579349B1 - Water treatment apparatus using plasma-membrane and method using the same - Google Patents

Abstract

The present invention relates to a reaction tank containing waste water; A ceramic membrane, which is contained in the reaction tank and has a hollow portion formed therein, the porous membrane having a plurality of pores; A gas inlet connected to one side of the reaction tank and communicating with the hollow portion to introduce a gas; And a plasma discharge part inserted in the hollow part to generate an electric discharge to activate the introduced gas; And the activated gas is supplied into the wastewater through the pores.
The present invention relates to a method for manufacturing a ceramic membrane hollow filter, comprising: introducing a gas into the ceramic membrane hollow using a wastewater treatment apparatus; Applying a voltage to the discharge electrode to generate a plasma to activate the introduced gas; And the activated gas is supplied into the wastewater to purify the wastewater; To a wastewater treatment method.

Description

[0001] The present invention relates to a plasma-membrane-based wastewater treatment apparatus and a wastewater treatment method.

The present invention relates to a wastewater treatment apparatus and a wastewater treatment method using a plasma membrane for treating pollutants or harmful microorganisms in a water quality.

Industrial wastewater, waste gas and waste containing many hazardous substances and refractory materials are generated along with the development of industrial technology, and studies for efficient treatment of such pollutants are actively conducted.

Particularly, as an example of a wastewater treatment method, there is known an underwater plasma generator in which an electrode is immersed in wastewater to be treated, and then a high voltage pulse is applied to the electrode to generate an active radical in water to perform a purification treatment.

However, in such an underwater plasma generator, since an electrode for generating a discharge is in a state of being submerged in water, electric power applied to the electrode is conducted through the wastewater, so that plasma generation is not easy and there are many problems in practical application.

In addition, radicals and ions of radicals, ions, ozone, and other various active ingredients generated by the plasma have the advantage of highly reactive activity, but their lifespan is very short, . Thus, effective utilization of electrical energy used in the production of these active ingredients requires that the active ingredient be brought into contact with water as soon as it is produced and that the reaction rate be maximized.

KR 10-2012-0028771 (public number)

The present invention provides a wastewater treatment apparatus using a plasma-membrane capable of maximizing the reaction rate, which can be brought into contact with water immediately after the active ingredient is produced.

The present invention relates to a reaction tank containing waste water; A ceramic membrane, which is contained in the reaction tank and has a hollow portion formed therein, the porous membrane having a plurality of pores; A gas inlet connected to one side of the reaction tank and communicating with the hollow portion to introduce a gas; And a plasma discharge part inserted in the hollow part to generate an electric discharge to activate the introduced gas; And the activated gas is supplied into the wastewater through the pores.

The present invention relates to a method for manufacturing a ceramic membrane hollow filter, comprising: introducing a gas into the ceramic membrane hollow using a wastewater treatment apparatus; Applying a voltage to the discharge electrode to generate a plasma to activate the introduced gas; And the activated gas is supplied into the wastewater to purify the wastewater; And a method for treating wastewater.

The present invention minimizes the loss of the activated gas by allowing the activated gas to be immediately dispersed in water through the pores formed in the ceramic membrane and maximizes the contact area of the activated gas and the liquid, Microorganisms can be effectively removed.

1 is a view showing a configuration of a waste water treatment apparatus according to the present invention.
2 is a view showing a plasma discharge unit of a wastewater treatment apparatus according to the present invention.
3 is a flow chart of a wastewater treatment method according to the present invention.
FIG. 4 is a graph showing the removal efficiency of Reactive Blue 4 according to Experimental Example of the present invention. FIG.
FIG. 5 is a graph showing the removal efficiency of Orange II according to the experimental example of the present invention. FIG.

The present invention relates to a wastewater treatment apparatus, comprising: a reaction tank containing wastewater; A ceramic membrane, which is contained in the reaction tank and has a hollow portion formed therein, the porous membrane having a plurality of pores; A gas inlet connected to one side of the reaction tank and communicating with the hollow portion to introduce a gas; And a plasma discharge part inserted in the hollow part to generate an electric discharge to activate the introduced gas; And the activated gas is supplied into the wastewater through the pores.

Here, the activated gas may be a gas containing an active component such as a radical or an ion generated by the plasma.

Also, one side of the inside of the reaction tank corresponds to the outside diameter of the ceramic membrane, and the reaction tank may further include a gas outlet.

The ceramic membrane may further include a coil surrounding the outer surface and contacting the ground electrode.

Further, the ceramic membrane is characterized by being hydrophobic.

In addition, the plasma discharge unit of the present invention includes a discharge electrode extending in the longitudinal direction and applying a voltage to generate a plasma; And a dielectric tube surrounding the outer surface of the discharge electrode; .

In particular, the discharge electrode may be made of stainless steel, carbon steel, copper, brass, titanium, tungsten or molybdenum, and the dielectric tube may be made of a quartz tube, a glass tube or a ceramic tube.

In a specific embodiment, the diameter of the pores is 0.8 to 10 mu m.

Further, the apparatus may further include a wastewater supply unit for supplying the wastewater to the reaction tank, and the gas may be at least one of air, oxygen, nitrogen, and argon.

The present invention relates to a method of treating wastewater, comprising the steps of introducing gas into the ceramic membrane hollow using a wastewater treatment apparatus; Applying a voltage to the discharge electrode to generate a plasma to activate the introduced gas; And the activated gas is supplied into the wastewater to purify the wastewater; .

Here, the voltage applied to the discharge electrode may be 5 to 30 kV, and the frequency of the voltage applied to the discharge electrode may be 0.5 to 1000 kHz.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

2 is a view showing a plasma discharge unit of a wastewater treatment apparatus according to the present invention, Fig. 3 is a flowchart of a wastewater treatment method according to the present invention, Fig. 4 is a flow chart of a wastewater treatment apparatus according to the present invention, FIG. 5 is a graph showing removal efficiencies of Reactive Blue 4 according to an experimental example of the present invention, and FIG. 5 is a graph showing removal efficiencies of Orange II according to an experimental example of the present invention. Hereinafter, the apparatus and method for treating wastewater using the plasma membrane according to the present invention will be described in detail with reference to FIGS. 1 to 5 and embodiments.

1, a wastewater treatment apparatus according to the present invention includes a reaction tank 100 containing wastewater, a hollow portion 220 formed in the reaction tank 100, and a plurality of pores 210 formed therein, The membrane 200 is connected to one side of the reaction tank 100 and is inserted into the hollow portion 220 and the gas inlet 110 through which the gas flows in communication with the hollow portion 220, And a plasma discharge unit 300 for activating the gas.

The reaction tank 100 may have a cylindrical shape or an L shape, and a gas inlet 110 may be formed at one side and a gas outlet 120 may be formed at the other side. At this time, the gas outlet 120 is preferably formed on the upper part. The gas inlet 110 may be formed at one end of the lower portion and the gas outlet 120 may be formed at the other end of the upper portion. In addition, the body of the reaction tank 100 is formed with an inlet through which the wastewater flows and an outlet through which the purified wastewater flows out.

The ceramic membrane 200 has a cylindrical shape having a hollow portion 220 formed therein, and is characterized in that the ceramic membrane 200 is hydrophobic.

Here, the term 'hydrophobic' means a property of not easily bonding with water molecules. In the present invention, it may be possible to prevent penetration of water into the ceramic membrane 200. The ceramic membrane 200 of the present invention can be subjected to a surface treatment with a hydrophobic property and can be subjected to surface treatment by coating polyvinylidene fluoride (PVDF), polyethersulphone (PES), or polytetrafluoroethylene (PTFE) can do.

Particularly, the ceramic membrane 200 of the present invention is prepared by diluting a ceramic resin (KP-18C, Shin-Etsu Chemical Co., LTd, Japan) with distilled water to prepare an aqueous solution of 1.75 wt% A hydrophobic ceramic membrane (200) having a surface treated with ultrasonic waves for 4 hours, taken out of the aqueous solution, naturally dried at room temperature for 1 hour, and dried at 100 to 120 ° C for 4 hours was used.

The pores 210 formed in the ceramic membrane 200 are 0.8 to 10 μm or 1 to 8 μm in diameter. For example, the average pore 210 having a size of 1.2 탆 was used. The pore 210 of the ceramic membrane 200 used in the present invention is very fine, so that the gas is finely dispersed in the water through the pore 210. In this case, So that vapor / liquid contact can be made extremely large.

2, the plasma discharge unit 300 includes a discharge electrode 310 and a dielectric tube 320. The discharge electrode 310 is formed of stainless steel, carbon steel, copper, brass, titanium, Tungsten or molybdenum, and a dielectric tube 320 is formed on the outer surface. In particular, the dielectric tube 320 may limit the amount of charge delivered by one microdischarge and cause the microdischarge to spread throughout the electrode. For this, the dielectric tube 320 may be made of a material having a high dielectric constant. For example, glass, quartz or ceramics.

Particularly, the plasma discharge unit 300 of the present invention is spaced apart from the hollow portion 220 of the ceramic membrane 200 by a predetermined distance. The predetermined interval may be maintained at 1 to 5 mm. For example, the outer diameter of the ceramic membrane 200 was 11 mm, the inner diameter and outer diameter of the dielectric tube 320 were 2 mm and 4 mm, respectively, and the distance between the inner wall of the ceramic membrane 200 and the outer wall of the dielectric tube 320 was 3 mm.

The space between the plasma discharge part 300 and the ceramic membrane 200 is communicated with the gas inlet 110 so that the gas inlet 110 The gas is introduced into the space, and the plasma discharge part generates an electric discharge to activate the introduced gas.

Here, the gas may be at least one of air, oxygen, nitrogen, and argon, and air may be used as an example. Here, air means a colorless, transparent, odorless gas mixture in the lower atmosphere of the atmosphere surrounding a mixture of nitrogen, oxygen, argon, and carbon dioxide.

In one embodiment, the outer diameter of the ceramic membrane 200 of the present invention may correspond to one side of the interior of the reactor 100 of the present invention. This is to prevent water from flowing into the plasma reaction part when the outside diameter of the ceramic membrane 200 corresponds to the inside diameter of the reaction tank 100 to stop the operation of the wastewater treatment device.

A coil 230 is formed on the outer surface of the ceramic membrane 200 of the present invention. The coil 230 may be connected to the ground electrode 231.

Here, the ground electrode 231 may be a metal rod, a metal plate, or a metal mesh embedded in the ground for grounding, and the present invention may be a Y-shaped ground electrode.

3 is a flow chart illustrating a wastewater treatment process according to an embodiment of the present invention.

Referring to FIG. 3, introduction of gas into the hollow portion 220 of the ceramic membrane 200 using a wastewater treatment apparatus; Applying a voltage to the discharge electrode 310 to generate a plasma to activate the introduced gas; And the activated gas is supplied into the wastewater to purify the wastewater; .

More specifically, the gas flows into the space between the ceramic membrane 200 and the plasma discharge unit 300 through the gas inlet 110.

When a voltage having a predetermined frequency is applied to the discharge electrode 310 and an electric field is generated in the plasma discharge unit 300, a space between the dielectric tube 320 and the inner wall of the ceramic membrane 200, Plasma is generated in the pores 210 to activate the introduced gas. Many dissociation and ionization reactions are possible with respect to the activated gas, and only the main reaction schemes are summarized as follows.

O ₂ + e? O + O + e (Scheme 1)

N ₂ + e - > N + N + e (scheme 2)

O + O ₂ ? O ₃ (Scheme 3)

N ₂ + e? N ₂ ⁺ + e (scheme 4)

O ₂ + e? O ₂ ⁺ + e (scheme 5)

O ₂ + e? O ₂ (Scheme 6)

O ₂ + e? O + O (Scheme 7)

N ₂ + e? N ₂ ^* (Reaction Scheme 8)

In the above reaction formula, e represents a high energy electron and N ₂ ^* represents a nitrogen molecule in an excited state. In addition, activated gases such as O, O ₃ , N, N ₂ ⁺ , O ₂ ⁺ , O ₂ ^- and the like are dispersed evenly in water in the form of fine bubbles through the ceramic membrane 200, Lt; RTI ID = 0.0 > components.

On the other hand, the voltage applied to the discharge electrode 310 needs to be adjusted appropriately. If the voltage is too high, the water molecules can be directly decomposed by the electric field, and if the voltage is too low, the gas in the bubble may not be ionized. Considering this point, it is preferable that the voltage applied to the discharge electrode 310 is 5 to 30 kV.

In addition, the frequency of the voltage applied to the discharge electrode 310 needs to be adjusted properly. If the frequency is too high, the electric power may be inefficiently used due to the electric matching problem. If the frequency is too low, the plasma may not be generated and the gas may not be activated. Therefore, It is preferable that the frequency applied to the capacitor 310 is 0.5 to 1000 kHz.

Hereinafter, in order to facilitate understanding of the present invention, experimental examples will be described in detail. It should be understood, however, that the following examples are illustrative only and are not intended to limit the scope of the present invention. Experimental examples of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

< Experimental Example >

Experimental Example 1. Preparation of Simulated Wastewater

In the experimental example of the present invention, organic matter or microorganisms were diluted in distilled water for the production of simulated wastewater. Reactive blue (C ₂₃ H ₁₄ C ₁₂ N ₆ O ₈ S ₂ ) was used as the organic water pollutant and E. coli was used as the microorganism. Reactive Blue and Acid Red 4 used in the experimental examples of the present invention were purchased from Sigma-Aldrich.

The concentration of organic pollutants was 3.5 ~ 17.5 mg / L, and the initial concentration of E. coli was 1 × 10 ⁷ cfu / mL (cfu: colony forming unit).

Also, the volume of the simulated wastewater was 800 mL, and flowed into the wastewater treatment device at a flow rate of 100 L / min by the liquid pump. At this time, alternating current or pulse high voltage can be used in the wastewater treatment apparatus, and in the experimental example of the present invention, AC high voltage having a frequency of 60 Hz was used. The removal efficiency of organic water pollutants was analyzed by a spectrophotometer. Petrifilm for E. coli from 3M company was used for measuring the killing efficiency of E. coli. All experiments were also carried out at temperatures between 15 and 25 ° C.

Experimental Example  2. Wastewater treatment method using wastewater treatment device.

For the wastewater treatment performance analysis, samples were collected periodically and their concentrations were measured. The organic wastewater concentration was analyzed using UV / visible spectrophotometer (Model UV-2500, Labomed, Inc.), Reactive Blue at 595 nm and Acid Red 4 at 508 nm.

When a high voltage is applied to the discharge electrode 310 while the gas is continuously flowing into the wastewater treatment apparatus of the present invention, the gas is activated inside the dielectric tube 320 formed of the glass tube. Particularly, oxygen and water vapor in the air dissociate and various kinds of oxidizing components such as ozone, oxygen atoms and hydroxyl radicals are generated.

4 is a graph showing the removal efficiency of Reactive Blue 4 measured by applying the voltage of 15.6 kV (effective value) to fix the discharge power at 2 W and measuring the applied time. As shown in FIG. 4, it was found that when the initial concentration was 3.5 mg / L, it was completely removed for about 6 minutes, about 10 minutes for 8.75 mg / L and about 14 minutes for 17.5 mg / L.

Table 1 shows the removal efficiencies of other organic substances and Escherichia coli measured at the operating condition (2W) as shown in FIG. 4 after 10 minutes. As shown in Table 1, Acid Red 4, Orange II and Escherichia coli were found to be 100% removed in 10 minutes. In particular, FIG. 5 shows that before and after treatment of Orange II, E. coli was removed.

Therefore, it was found that the wastewater treatment apparatus of the present invention is very effective for water treatment.

Removal performance after 10 minutes treatment (%)

Acid Red 4

100% (initial concentration 5 mg / L) Orange II

100% (initial concentration 5 mg / L)
Escherichia coli 100% (initial concentration: 1 x 10 &lt; ⁷ &gt; cfu / mL)

100: Reactor
110: gas inlet 120: gas outlet
200: Ceramic membrane
210: Pore 220: Hollow
230: coil 231: ground electrode
300: Plasma discharge unit
310: discharge electrode 320: dielectric tube

Claims (15)

A reaction tank containing waste water;
A hydrophobic ceramic membrane, which is contained in the reaction tank and has a hollow portion therein, the hydrophobic ceramic membrane having a plurality of pores;
A gas inlet connected to one side of the reaction tank and communicating with the hollow portion to introduce a gas; And
A plasma discharge part inserted in the hollow part to cause an electric discharge to activate the introduced gas; Wherein the activated gas is supplied into the wastewater through the pores. The method according to claim 1,
Wherein one side of the inside of the reaction tank corresponds to an outer diameter of the ceramic membrane. The method according to claim 1,
Wherein the reaction tank further comprises a gas outlet. delete The method according to claim 1,
Wherein the ceramic membrane comprises a coil surrounding the outer surface. 6. The method of claim 5,
Wherein the coil is in contact with the ground electrode. The method according to claim 1,
The plasma discharge unit
A discharge electrode extending in the longitudinal direction and applying a voltage to generate a plasma; And
A dielectric tube surrounding the outer surface of the discharge electrode; And a waste water treatment device. 8. The method of claim 7,
Wherein the discharge electrode is made of stainless steel, carbon steel, copper, brass, titanium, tungsten or molybdenum. 8. The method of claim 7,
Wherein the dielectric tube is made of a quartz tube, a glass tube, or a ceramic tube. The method according to claim 1,
And the diameter of the pores is 0.8 to 10 mu m. The method according to claim 1,
Further comprising a wastewater supply unit for supplying the wastewater to the reaction tank. The method according to claim 1,
Wherein the gas is at least one of air, oxygen, nitrogen, and argon. A wastewater treatment apparatus according to any one of claims 1 to 3 and 5 to 12,
Flowing a gas into the ceramic membrane hollow portion;
Applying a voltage to the discharge electrode to generate a plasma to activate the introduced gas; And
The activated gas is supplied into the wastewater to purify the wastewater; &Lt; / RTI &gt; 14. The method of claim 13,
Wherein the voltage applied to the discharge electrode is 5 to 30 kV. 14. The method of claim 13,
Wherein the frequency of the voltage applied to the discharge electrode is 0.5 to 1000 kHz.

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