KR20030087801A - Wastewater treatment apparatus and method using ultrasonic generator and photo-catalytic material - Google Patents

Abstract

PURPOSE: Provided are a water treatment apparatus and a water treatment method using ultrasonic wave and photocatalyst, the apparatus and method being capable of eliminating both of hydrophilic contaminants and hydrophobic contaminants. CONSTITUTION: The apparatus comprises a reaction chamber(100), an ultrasonic generator(400) installed on the inside of the reaction chamber(100) at a side thereof, a photocatalyst(200) provided on the inside of the reaction chamber(100) at the other side thereof, a compartment(500) provided between the ultrasonic generator(400) and the photocatalyst(200), an oxygen supply unit for supplying oxygen to the inside of the reaction chamber(100), and a pH adjusting unit(600) for adjusting raw water to be introduced into the reaction chamber(100). The method comprises the steps of adjusting pH of raw water to pH 7, applying ultrasonic wave to raw water, and decomposing/adsorbing contaminants by photocatalyst while applying UV rays to the raw water.

Description

WATER WATER TREATMENT APPARATUS AND METHOD USING ULTRASONIC GENERATOR AND PHOTO-CATALYTIC MATERIAL}

The present invention relates to a water treatment apparatus and a water treatment method for removing contaminants contained in various wastewaters, such as industrial wastewater and domestic sewage, using ultrasonic waves and photocatalysts.

Wastewater, such as industrial wastewater and domestic sewage, contains a large amount of various pollutants such as organic, inorganic, or heavy metals, and these pollutants vary greatly in size, specific gravity, or physical properties.

Conventional water treatment systems use the specific properties of each pollutant contained in the wastewater to remove these pollutants one by one. For example, pollutants that are heavier than water, such as heavy metals, are precipitated and removed. Contaminants that have a low specific gravity without mixing with them are removed by a vacuum device such as a screen device, a garden or a suction scum skimmer. In addition, the suspended solids in the waste water were precipitated by adding a flocculant or removed by a bubble generator called a pressure booster.

Thus, the water treatment system of the past is a form in which some of the aforementioned elements are combined in a suitable form as necessary.

However, the water treatment system having such a structure has a disadvantage of requiring a long treatment time from the inflow of the waste water to the discharge of the purified water, and due to the small amount of treatment per hour, the system has to be enlarged in order to treat a large amount of waste water. There was a costly disadvantage. However, a further disadvantage is that contaminants that exist in ionic state or in very fine size remain unremoved.

As a method for improving such a conventional problem, a photocatalytic water treatment system for removing fine contaminants contained in wastewater by photooxidation and reduction by using a photocatalyst, such as titanium dioxide, has recently been in the spotlight. .

The water treatment system using the oxidation and reduction of photocatalysts is generally classified into a suspension system in which photocatalytic materials are used in powder form and an immobilization system in which a photocatalytic material is supported on a porous object. There is a problem that the photocatalyst must be recovered after termination.

However, the photocatalytic water treatment system described above has a disadvantage in that hydrophobic contaminants contained in the wastewater cannot be removed at all, regardless of whether they are suspended or immobilized.

The present invention has been made to improve such a problem, and an object of the present invention is to provide a water treatment apparatus and a water treatment method capable of removing hydrophobic contaminants as well as hydrophilic contaminants contained in waste water.

In addition, an object of the present invention is to provide a water treatment apparatus and a water treatment method capable of removing hydrophilic contaminants with high efficiency in a short time by allowing the oxidation and reduction reactions of the photocatalyst to occur more actively than before.

1 shows a water treatment system of one embodiment in which the water treatment apparatus of the present invention is employed.

FIG. 2 is a sectional view of the reaction treatment tank shown in FIG.

[Description of Drawing Reference]

100 reaction tank, 200 photocatalyst medium,

300 ... UV generating means, 400 ... Ultrasound generating means,

500 ... bulk, 600 ... pH adjustment tank.

In the water treatment method of the present invention for solving the above technical problem, in the water treatment method for removing contaminants contained in the waste water, hydrophobic contaminants in the waste water is mainly removed in the ultrasonic treatment process, hydrophilic contamination contained in the waste water The material is characterized in that it is mainly removed in the optical processing process. If necessary, the ultrasonic treatment process and the optical treatment process may be repeated.

As is well known, holes on the surface of photocatalysts such as photoexcited titanium dioxide have a high oxidation potential. Therefore, when water molecules come into contact with the photocatalyst in the photoexcited state, OH- ions (OH radicals) are formed, and the hydrophilic pollutants in the wastewater are oxidatively decomposed by the oxidation of the OH radicals. On the other hand, while hydrophilic pollutants adsorbed on the surface of the photocatalyst are decomposed by radicals, hydrophobic pollutants remain as intermediate products in the wastewater. According to the present invention, the hydrophobic pollutants are decomposed by ultrasonic waves and thus contained in the wastewater. Almost all of the hydrophobic contaminants are removed.

Here, the removal process of hydrophobic contaminants by ultrasonic wave is briefly described.

First, when ultrasonic waves are injected into the waste water, fine bubbles are generated in the waste water, and the bubbles grow larger in size while rising to the surface, and collapse when reaching a certain size. When the bubble collapses, a high-temperature, high-pressure reaction field is generated around the collapsed bubble. At this time, hydrophobic contaminants in the reaction field are volatilized or decomposed and removed from the wastewater.

Therefore, according to the water treatment method of the present invention as described above, the fine contaminants contained in the waste water can be completely removed.

In addition, in the water treatment method of the present invention, it is preferable to lower the pH of the wastewater to 7 or less by introducing an acidic solution or the like into the wastewater before or before the wastewater is provided to the ultrasonic treatment process and / or the optical treatment process.

In this way, the possibility of generating radicals or the frequency of occurrence of radicals in the optical treatment process is much higher, and thus the efficiency of oxidative decomposition of hydrophilic contaminants in wastewater is improved, and acid sterilization effect can be seen.

More preferably, the amount of dissolved oxygen in the wastewater is increased by supplying oxygen before or during performing the ultrasonic treatment process and / or the optical treatment process.

In this way, a larger number of fine bubbles are formed in the sonication process so that hydrophobic contaminants in the waste water can be more easily removed in a large amount, and in the optical treatment process, more radicals are formed and the oxidative decomposition reaction is promoted to promote hydrophilicity. More contaminants can be removed.

The water treatment apparatus of the present invention for performing the above-described water treatment method basically includes an ultrasonic wave generating means for ultrasonically treating the wastewater and a photocatalyst medium and UV generating means for optically treating the wastewater. pH adjusting means and oxygen supply means for adjusting the pH may be additionally installed. In addition, a partition wall may be additionally installed between the ultrasonic wave generating means, the photocatalyst medium and the UV generating means to partially block them.

More preferably, a plurality of the ultrasonic wave generating means, the photocatalyst medium and the UV generating means are alternately arranged, and partition walls are provided therebetween.

In this case, a photocatalyst in the form of powder may be used as the photocatalyst medium, but in this case, the photocatalyst should be recovered from the purified water, so that there is no problem of recovery by using a carrier having the photocatalyst fixed to a material of a predetermined shape if possible. It is preferable.

In addition, as the oxygen source supplied to the wastewater through the oxygen supply means, a normal air or a gas such as oxygen (O ₂ ) and ozone (O ₃ ) or a liquid such as hydrogen peroxide (H ₂ O ₂ ) may be used.

According to the water treatment apparatus of the present invention configured as described above, the ultrasonic wave generated by the ultrasonic wave generating means by the partition wall partially blocking the ultrasonic wave generating means and the photocatalyst medium is reflected to the photocatalyst medium or the intensity is reduced. Since it reaches, the photocatalyst can be prevented from falling off from the carrier.

Thus, the problem of recovering the photocatalyst is prevented.

In addition, according to the water treatment apparatus of the present invention, the oxygen supplied excessively in the waste water reacts with the photocatalyst to generate more radicals and promotes oxidative decomposition of the pollutants, thereby increasing the removal efficiency of the pollutants.

In addition, by adjusting the pH of the waste water by the pH control means it is possible to increase the generation or frequency of the generation of OH- ions by the photocatalyst to increase the removal efficiency of hydrophilic pollutants.

Hereinafter, a water treatment apparatus and a water treatment method according to a preferred embodiment of the present invention with reference to the accompanying drawings will be described in detail.

Here, the protection scope of the present invention is not limited to the embodiments described below, for example, even if it is not mentioned in the present specification will be understood to be included in the present invention if it is a known component.

1 shows a water treatment system of one embodiment in which the water treatment apparatus of the present invention is employed.

In the figure, reference numeral 10 denotes a pretreatment tank for removing a light but bulky floating object such as a piece of wood or a piece of cloth contained in the wastewater.

One end of the pipe connected to the suction pump P is locked to the inner bottom of the pretreatment tank 10, and the other end of the pipe is equipped with a filtering net. In addition, a water supply line for replenishing wastewater is connected to the pretreatment tank 10.

Accordingly, when the suction pump P is driven, the waste water stored in the pretreatment tank 10 is sucked into the pipe, and contaminants having a smaller size than the mesh of the filter network (not shown) installed at the end of the pipe are sucked together with the waste water. .

Subsequently, the contaminants sucked together with the wastewater in the pretreatment tank 10 are discharged to the settling tank 20 installed at the rear of the pretreatment tank through the pipe, and the heavy contaminants contained in the wastewater in the settling tank 20 are subject to gravity. It sinks to the bottom (sedimentation) and light contaminants float above the water surface.

On the other hand, contaminants settled on the bottom of the settling tank is intermittently removed through a drain pipe installed on one side of the bottom, waste water toward the pH adjustment tank 600 installed behind the settling tank through a discharge pipe installed at a position higher than the drain pipe. Is discharged.

The pH adjusting tank 600 is an embodiment of the pH adjusting means of the present invention, the agitating blade (610) driven by a motor (M) is installed in the inner center of the pH adjusting tank, pH adjusting chemicals The other side of the pipe, one side of which is connected to the tanks 620 and 630, is installed on the upper side or side of the pH adjustment tank.

In addition, a pH meter 640 for detecting the pH of the wastewater is provided in the pH adjustment tank.

In this embodiment, sulfuric acid solution and sodium hydroxide solution were used as the chemicals stored in the pH adjusting chemical tanks 620 and 630.

In the pH adjustment tank 600, for example, the pH of the wastewater is adjusted to 5, but when the detection value of the pH meter 640 is higher or higher, for example, an additional sulfuric acid solution is added, and when it is lower, sodium hydroxide solution is added. To adjust the pH of the wastewater to 5.

Thereafter, the pH-adjusted wastewater is discharged through the conduit toward the reaction treatment tank 100 of the present invention installed behind the pH adjustment tank.

2 is a view illustrating the reaction treatment tank of the present embodiment in more detail. In the reaction treatment tank 100, an ultrasonic wave generating unit 400 is installed on the downstream side of the waste water and the photocatalyst medium 200 and the upstream side. UV generating means 300 is installed.

In addition, these ultrasonic wave generating means 400 and the photocatalyst medium 200 are partially blocked by the partition wall 500 provided across the inside of the reaction treatment tank 100.

As the photocatalyst medium 200, photocatalyst particles in the form of powder or those in which the photocatalyst particles are fixed to the carrier may be used, but in the present embodiment, a fixed photocatalyst which does not need to recover the photocatalyst after water treatment is used.

In addition, in the present embodiment, the oxygen supply means employs a diffuser 110 installed at the inner bottom of the reaction treatment tank 100 and one pipe connected to one of the hydrogen peroxide storage tanks 130 shown in FIG. 1. At one end of the diffuser, a blower 120 is installed, and an end of a pipe connected to the hydrogen peroxide storage tank is installed at the top, side, or bottom of the reaction tank.

Therefore, in the reaction treatment tank 100, the optical treatment by the photocatalyst medium 200 and the UV generating means 300 and the ultrasonic treatment by the ultrasonic generating means 400 are performed at the same time, so that the hydrophilic pollutants contained in the waste water. And hydrophobic contaminants are removed.

In the reaction treatment tank of this embodiment configured as described above, contaminants contained in the waste water are removed through the following process.

First, when the wastewater adjusted to pH 5 in the pretreatment step flows into the upstream side of the reaction treatment tank, hydrophilic contaminants contained in the wastewater are removed by optical treatment.

That is, when power is applied to the UV generating means 300 to emit ultraviolet rays, holes are formed on the surface of the photocatalyst medium 200 and radicals are generated in the vicinity thereof. Therefore, the generation of radicals is much higher than in the prior art, and further hydrogen peroxide water is added to the wastewater being treated to generate a larger amount of radicals.

The radicals oxidize and decompose hydrophilic pollutants contained in the wastewater. At this time, oxygen from the air or hydrogen peroxide water supplied through the acid pipe 110 promotes the oxidative decomposition reaction and shortens the wastewater treatment time.

Meanwhile, wastewater from which hydrophilic contaminants are removed in the optical treatment process flows downstream of the reaction treatment tank 100 through a gap formed between the reaction treatment tank 100 and the partition wall 500 and undergoes an ultrasonic treatment process.

In the ultrasonic treatment process, hydrophobic contaminants are removed. When ultrasonic waves are emitted from the ultrasonic generator 400 installed in the reaction treatment tank 100, fine bubbles are generated in the waste water and at the same time, high temperatures are generated during the collapse of the bubbles. A high pressure reaction field is formed, and hydrophobic contaminants under the influence of this reaction field are volatilized or oxidized and removed from the waste water.

Here, the ultrasonic treatment process and the optical treatment process of the present invention may be performed only once in one place as in this embodiment, but the treatment process may be repeatedly performed alternately, and each process may be performed separately in another processing tank adjacent to and installed. It may be.

Thereafter, the wastewater discharged through the above process is temporarily stored in the discharge tank 30 installed at the rear of the reaction treatment tank 100 and discharged as it is in a stream or provided to another treatment process.

Here, reference numeral L is a leveler for measuring the water level.

Hereinafter, the contaminant removal efficiency when the optical treatment and the ultrasonic treatment are performed in accordance with the water treatment method of the present invention for the influent of the industrial complex A treatment terminal will be described.

Experiment 1

This is the case where the wastewater of pH7.8 collected from the terminal A of the industrial complex is continuously provided to the optical and ultrasonic treatment processes to remove contaminants contained in the wastewater, thereby changing the amount of H ₂ O ₂ used.

Operational conditions, experimental conditions, and water quality test results after water treatment are as follows.

* Operation condition

① Flow rate: 1ton / day

② pH: 5

③ UV generating means: 28ea × 39W

④ Ultrasonic generating means: 13ea × 450W (Use frequency range: 20 ~ 250 ㎑)

⑤ Variable: Usage of H ₂ O ₂

* Experimental condition

① Volume of reaction treatment tank: about 600ℓ

② Retention time of wastewater in reaction tank: about 12 hours

③ Shape of Reaction Treatment Tank: Rectangle

④ Thickness of bulkhead: about 10mm

⑤ Carrier: Silica Beads

Table 1

H ₂ O ₂ (mg / L) COD mn Throughput BOD Throughput SS Throughput Chromaticity Throughput 0 25.5 43.3 0.9 96.1 9 86.2 2.4 95.3 25 19 57.7 0.9 96.1 7 89.2 4.8 90.6 100 7.0 84.4 0.9 96.1 2.4 96.3 2.1 95.9 200 11.6 74.2 0.3 98.7 5.1 92.1 2.1 95.9 400 13.7 69.5 0.5 97.8 7.7 88.2 5.8 88.7 600 26.8 42.2 0.1 99.6 4.7 92.8 4 92.2

As can be seen from Table 1, BOD throughput or SS throughput and color throughput but maintain a substantially constant level significantly regardless of the H ₂ O ₂ uiyang, COD throughput showed a large variation depending on the amount of H ₂ O ₂ using .

According to this experiment, it was found to be efficient when the amount of H ₂ O ₂ used was approximately 100 to 400 mg / L. In addition, in the water treatment system of FIG. 1, the test wastewater was treated according to the above operating conditions and experimental conditions, and water quality test was performed.

Experiment 2

Experiment 2 is a case where the wastewater of industrial complex A is continuously provided to the optical treatment process and the ultrasonic treatment process, but it is treated by changing the pH of the wastewater.

The test conditions, the operating conditions and the water quality test results after the water treatment are as follows.

Operating conditions

① Flow rate: 1ton / day

② H ₂ O ₂ : 400 (mg / L)

③ UV generating means: 28ea × 39W

④ Ultrasonic generating means: 13ea × 450W (Frequency range: 20 to 250 kHz)

⑤ Variable: pH of waste water

Experimental condition

Same as experiment 1

TABLE 2

pH COD mn Throughput BOD Throughput SS Throughput Chromaticity Throughput 3 9.1 79.8 1.3 94.3 - - 4.4 91.4 4 7.0 84.4 0.9 96.1 2.4 96.3 2.1 95.9 5 13.7 69.6 1.5 93.5 4.7 92.8 4.1 92.0 7.8 26.8 40.4 0.1 99.6 4.7 92.8 4 92.2

According to the experimental results of Table 2, as in Experiment 1, the BOD treatment rate and the like were not significantly affected by the pH, but the COD treatment rate was more efficient as the pH was lower, that is, the acid.

As described above, according to the water treatment apparatus and the water treatment method of the present invention, it can be seen that COD is reduced by about 30% and BOD by about 12% compared to the conventional photocatalytic water treatment method. It can be seen that it is removed with high efficiency.

In addition, in terms of chromaticity removal, the treatment efficiency was 88% when only the ultrasonic treatment was performed, and the processing efficiency was 84% when the optical treatment was only performed. More than 95 percent were almost perfect.

In addition, by using the photocatalyst on a carrier having a predetermined shape, the problem of recovering the photocatalyst from the reaction treatment tank could be essentially eliminated.

As described above, the present invention employs both ultrasonic waves and photocatalysts in the water treatment process, thereby removing hydrophobic pollutants with ultrasonic waves and hydrophilic pollutants with photocatalysts, thereby maximizing the purification efficiency of wastewater.

Claims (9)

In the water treatment method for removing contaminants contained in waste water, An ultrasonic treatment step of applying ultrasonic waves to the waste water; And Optical treatment process for applying photocatalyst and UV to the waste water; Water treatment method comprising a. The method of claim 1, And the ultrasonic treatment process and the optical treatment process are repeated. The method according to claim 1 or 2, A water treatment method characterized by treating so that the pH of the introduced or introduced wastewater is 7 or less. The method according to claim 1 or 2, A water treatment method characterized by supplying oxygen to wastewater in an ultrasonic treatment process and / or an optical treatment process. In the water treatment apparatus for removing contaminants contained in waste water, Ultrasonic generator for applying ultrasonic waves to the waste water; And Photocatalyst medium and UV generating means for optically treating the wastewater; Water treatment apparatus comprising a. The method of claim 5, And the ultrasonic generating means, the photocatalyst medium and the UV generating means are partially blocked by the partition wall. The method of claim 6, And the ultrasonic generating means, the photocatalyst medium and the UV generating means, which are partially blocked by the partition wall, are repeatedly provided. The method according to any one of claims 5 to 7, Water treatment apparatus further comprises a pH adjusting means for adjusting the pH of the waste water. The method according to any one of claims 5 to 7, Water treatment apparatus further comprises an oxygen supply means for supplying oxygen to the waste water.