KR100390652B1 - Method for treating a waste water using a photocatalytic reaction - Google Patents

Abstract

PURPOSE: A method for treating wastewater using photocatalytic reaction is provided to completely oxidize contaminants so that secondary contaminants are not generated and perform advanced treatment of recalcitrant organic matter by applying TiO2 photocatalytic oxidation system to leachate and wastewater treatment. CONSTITUTION: The method comprises a step of pretreating wastewater by coagulating and precipitating solids of wastewater, thereby removing the solids of wastewater, adjusting pH of the solid removed wastewater and stripping ammonia from the pH adjusted wastewater; a step of mixing the wastewater, powder type TiO2 catalyst and reaction supporting agent in a mixing tank(6); a step of oxidizing thus removing contaminants by flowing the mixed wastewater in a lower part of at least one photocatalytic reactor(7) and continuously and repeatedly circulating the mixed wastewater upward, wherein at least two or more of baffles in the center of which hole is formed are formed in the photocatalytic reactor with being spaced apart from each other in a certain distance, and a quartz tube in which an ultraviolet lamp is installed in such a way that the ultraviolet lamp is spaced apart from the quartz tube in a certain gap vertically passes through along the circumferential surface of the holes of the baffles; a step of obtaining a TiO2 separated effluent by passing the contaminant oxidized and removed mixed water through a catalyst recovery unit(9) in which filter pressure is maintained to 3 to 5 kg/cm¬2, a scraper is mounted, and a disc type clayish filter is installed; and a step of continuously flowing the removed TiO2 in the mixing tank again after continuously removing TiO2 accumulated on the clayish filter using the scraper.

Description

Method for treating a waste water using a photocatalytic reaction

The present invention relates to a wastewater treatment system using a photocatalytic reaction, and more specifically, can be operated stably by non-experts, and can be applied to the process regardless of seasonal changes and changes in leachate properties over landfill time and pollutants The present invention relates to a method for treating wastewater using a photocatalytic reaction in which a TiO ₂ photocatalytic oxidation device can be applied to leachate and wastewater treatment without causing secondary pollutants by highly oxidizing oxidized organic matter.

Due to the economic growth and population growth caused by the rapid industrialization, the disposal and disposal caused by the increase of general garbage and industrial waste has emerged as a major concern to lay the groundwork for the developed countries in the 21st century. In particular, leachate generated from landfills is a collection of various organic substances and pollutants, which requires complete disposal. It is estimated that leachate from landfills operated by local governments is about 14,000m3, and that leachate from private landfills by private companies is also estimated.

On the other hand, domestic leachate treatment technology has not been treated to a level that does not cause environmental pollution, and has become the main cause of the residents' opposition to landfill and civil complaints. This is because it is difficult to select a standardized process because the characteristics of the leachate generated in each landfill are different and the properties change as landfill proceeds. In addition, manure or livestock wastewater has a larger pollutant load than wastewater generation and may cause deterioration of water quality and eutrophication when it is not treated. Therefore, it is necessary to propose a new alternative to the wastewater treatment method. It is time for proper coping techniques to be applied to plating wastewater, paper wastewater, dyeing leather wastewater with high pollutant loads, and TNT (Trinitro toluene) wastewater, which can cause groundwater and soil contamination if proper water treatment is not accompanied.

Currently, each leachate and wastewater have difficulty in selecting an appropriate water treatment process for their own characteristics, and the selected treatment process also leaves technical difficulties for the operation manager due to difficulties in operation. In the existing treatment process, which is a biological or physicochemical treatment, hardly decomposable organic substances are not treated, and after treatment, secondary treatment materials such as sludge and concentrated water are generated to require post-treatment. There is a need for development of leachate and wastewater treatment technologies capable of performing highly advanced treatment of hardly degradable organic materials without releasing them.

In general, wastewater treatment is roughly classified into biological treatment and physicochemical treatment. The biological treatment is used for oxidation of biodegradable organic substances, and the physicochemical treatment is used for removal and oxidation of suspended substances and organic substances. Leachate, industrial wastewater (plating wastewater, dyeing leather wastewater, petrochemical wastewater, papermaking wastewater, TNT wastewater, etc.), and livestock wastewater with high concentrations of toxic and hardly degradable organic substances, and livestock wastewater can satisfy toxic and hardly degradable organic substances by biological treatment. Not only can it be removed to a sufficient level, but it is also difficult to operate due to toxic substances, and the physicochemical treatment method is associated with biological treatment to reduce the load of organic substances or to agglomerate, precipitate, or membrane toxic and hardly decomposable substances. Although it is removed by means of separation and adsorption, it is economically and technically sufficient to meet the discharge allowance standards for leachate, industrial wastewater (plating wastewater, dyeing leather wastewater, petrochemical wastewater, paper wastewater, TNT wastewater, etc.) and livestock wastewater. Many difficulties appeared.

Meanwhile, Advanced Oxidation Technology / Process (AOT / AOP) refers to a water treatment technology that increases the oxidation efficiency and oxidation rate of organic materials by generating OH radicals having much stronger oxidizing power than chemical oxidants. . OH radicals, which exhibit strong oxidizing power, are attracting attention as water treatment technologies in that they can completely oxidize CO ₂ and H ₂ O as well as biodegradable substances present in water. At present, the advanced oxidation technology has been applied to the treatment of groundwater having a relatively low concentration of pollutants or low color and turbidity components.

TiO ₂ photocatalytic oxidation reaction in the advanced oxidation technology occurs when electrons and holes generated when the photocatalyst absorbs light energy corresponding to energy larger than the bandgap energy of TiO ₂ (380 nm or less) react with organic materials. . In the semiconductor absorbing light energy, electrons move from the valence band (VB) to the conduction band (CB), and the generated electrons or holes react with oxygen in the water, hydrogen peroxide, and hydroxyl ions. It produces this powerful OH radical and decomposes pollutants in water to produce CO ₂ and H ₂ O. However, the electrons and holes thus formed cannot recombine at high speed to induce a photoreaction unless they can afford to meet the material to cause a reaction. Therefore, in the TiO ₂ photocatalytic oxidation technique, it is important for the TiO ₂ catalyst to absorb light energy above the bandgap energy to generate the same number of electron / hole pairs. That is, the generated holes contribute to the oxidation reaction and the electrons moved to the electron band should induce the reaction as much as possible to not contribute to the reduction reaction and provide a margin for recombination. In this case, the catalyst is excited by the generation of electron / hole pairs by light energy, and the excited catalyst reacts with hydroxyl ions adsorbed on the surface to generate OH radicals with strong oxidizing power. OH radicals lead to decomposition of organic matter. And react with a movement in the electronic e-electron acceptor is oxygen or hydrogen peroxide to slow the recombination of the hole or peroxide (Superoxide) radical (O ₂ ^- ·) to generate, hydroperoxides, hydroxy (Hydroperoxy) radical (HO ₂ ·) Proceed with decomposition of organic matter.

Since photocatalysts receive light energy and are excited and then recombined, the key technology is to slow down the recombination rate, to lower the bandgap energy of the catalyst, and to use light energy above the bandgap in an economical way.

This photocatalytic reaction proceeds on the semiconductor surface through the following steps.

1. When the semiconductor is excited using light energy, electrons and holes are generated. Electrons have reducing power in the conduction band, and holes have oxidizing power in the valence band.

2. A chemical photocatalytic reaction occurs in which electrons and holes are separated on the semiconductor surface to produce OH radicals. This reaction must occur at a rate faster than the rate at which the generated electrons and holes recombine again. Otherwise, no reaction occurs.

3. The organic materials on the surface of the semiconductor react with the electrons and holes to oxidize and reduce the organic materials. The OH radical then acts as a powerful oxidant.

4. When the reaction is completed, the organic matter is finally converted to CO ₂ and H ₂ O by the reaction, and moves from the semiconductor surface to the outside, and the semiconductor surface resumes the function of the catalyst.

In addition, the OH radical generated on the surface of the photocatalyst causes a simultaneous chain reaction with the organic material in the following manner.

1.Reaction of OH radicals formed on the surface of catalyst with organic material adsorbed on catalyst

2. Reaction of OH radicals separated from catalyst surface with organic material adsorbed on catalyst

3. Reaction of OH radicals generated on the surface of catalyst with organic material adjacent to catalyst

4. Reaction of OH radicals off the surface of the catalyst with organic materials adjacent to the catalyst

As a result, TiO ₂ photocatalytic oxidation techniques include the steps of exciting electron / hole pairs on the semiconductor surface; Preventing recombination of the excited electron / hole pairs; Actively generating OH radicals by electron / hole pairs; And the OH radical is a highly oxidized treatment technology utilizing the step of fully decomposing the organic material. This photocatalytic oxidation technology has been actively applied and developed in groundwater treatment, and has proved to be excellent, but it has been found to be toxic in leachate and industrial wastewater (plating wastewater, dyeing leather wastewater, petrochemical wastewater, papermaking wastewater, TNT wastewater, etc.) The treatment of hardly decomposable materials still remains a challenge for effective technical applications.

Related prior arts include US Pat. No. 5,462,674 (Korean Patent No. 185179) and Korean Patent Publication No. 98-50359. U. S. Patent No. 5,462, 674 describes a method and system for continuously purifying contaminated fluid. However, the patent uses an annular low pressure photocatalyst reactor, which has a disadvantage in that the fluid processing capacity of the reactor is lowered and the processing efficiency is lowered because a low pressure light source is used, which takes up a lot of space. In addition, although the system can treat contaminated groundwater and the like, it is difficult to treat general industrial wastewater. Korean Patent Laid-Open Publication No. 98-50359 discloses a wastewater treatment apparatus that can solve the problem of separation and recovery of a catalyst from a reaction tank using a powder and particulate photocatalyst having a high specific surface area, and is simple in operation and can continuously use the photocatalyst. However, the photocatalytic reactor mentioned in the patent has a disadvantage in that the photocatalytic reaction efficiency is lowered by stirring the slurry by a stirring pump.

In the present invention, the oxidized water and industrial wastewater (plating wastewater, dyeing leather wastewater, petrochemical wastewater, paper wastewater, TNT wastewater, etc.) using TiO ₂ photocatalytic oxidation technology capable of treating the pollutants to a stable level by completely oxidizing organic substances. And photocatalytic oxidation techniques such as optical energy intensity, photoreactor type, reaction temperature, concentration of pollutants, concentration of oxygen and reaction aids, internal pressure of reactor, and performance of catalyst for effective use in livestock wastewater treatment. By combining organically the individual water treatment process of the optimum water treatment method was developed, the present invention was completed based on this.

Therefore, the object of the present invention can be operated stably even for non-experts, can be applied to the process irrespective of seasonal changes and changes in leachate properties with landfill time, without causing secondary pollutants by the complete oxidation of pollutants The present invention provides a method for treating wastewater using a photocatalytic reaction, in which a TiO ₂ photocatalytic oxidation device can be applied to leachate and wastewater treatment for highly-degradable organic matter.

The treatment method of the wastewater of the present invention for achieving the above object is a step of coagulation and sedimentation and removal of solids in the wastewater, adjusting the pH of the wastewater from which the solids are removed, and then pretreating by degassing ammonia; Mixing the wastewater, the powdered TiO ₂ catalyst, and the reaction aid in a mixing tank (6); At least two or more baffles 14 having a hole formed at the center thereof are formed at intervals spaced apart, and the quartz tube 13 having the UV lamp 12 embedded therein is vertically spaced apart along the circumferential surface of the hole. Oxidizing and removing contaminants by introducing the mixed wastewater into a lower portion of at least one photocatalytic reactor (7) penetrating and continuously circulating upwards; By the oxidation of pollutants, filtering the mixture to remove the pressure can be fitted with a scraper 16 to be maintained at 3~5 kg / cm ^2, passed through the catalyst collector 9 is disc-shaped clay filter 15 installed TiO ₂ Obtaining treated water from which is separated; And continuously removing TiO ₂ accumulated in the clay filter 15 with the scraper 16, and then removing the TiO ₂ continuously into the mixing tank 6 again.

1 is a process diagram schematically showing an overall system for treating wastewater using a TiO ₂ photocatalytic oxidation technique according to the present invention.

FIG. 2 is a view schematically showing a TiO ₂ photocatalytic oxidation device for advanced treatment of wastewater used in the present invention.

3 is a view schematically showing a TiO ₂ photocatalytic oxidation reactor used in the present invention.

4 is a process diagram schematically showing a pretreatment process before oxidation treatment of the TiO ₂ photocatalyst according to the present invention.

Fig. 5 is a schematic diagram showing a recovery apparatus (clay filter) for separating powdered TiO ₂ used in the present invention from treated water.

※ Explanation of code about main part of drawing ※

1. Flow rate adjusting tank 2. Coagulation reaction tank 3. Settling tank

4. pH adjusting tank 5. Ammonia degassing column 6. Mixing tank

7. Photocatalytic Oxidation Reactor 8. Neutralization Tank 9. Catalytic Recovery

10. Discharge tank 11. Dehydrator 12. UV lamp

13. Quartz tube 14. Baffle 15. Clay filter

16. Scraper 17. Fixed shaft 18. Drain

19. Catalyst (foreign material) recovery port →. Flow of fluid

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

The present invention uses the TiO ₂ photocatalytic oxidation technology to oxidize toxic and hardly degradable substances in leachate, industrial wastewater (plating wastewater, dyeing leather wastewater, petrochemical wastewater, paper wastewater, TNT wastewater, etc.) and livestock wastewater. The present invention relates to an advanced treatment method for oxidizing toxic and hardly decomposable organic substances present in leachate, industrial wastewater, and livestock wastewater to an environment-friendly stable substance without generating secondary pollutants using ultraviolet rays and TiO ₂ . Hereinafter, the term 'wastewater' is used to include leachate and industrial wastewater (plating wastewater, dyeing leather wastewater, petrochemical wastewater, papermaking wastewater and / or TNT wastewater) and livestock wastewater treatment unless otherwise stated.

In general, TiO ₂ photocatalytic oxidation technology tends to reduce the effect of photocatalytic oxidation when the chromaticity, turbidity, and organic substance concentration are high. Therefore, in order to achieve effective treatment efficiency by applying the TiO ₂ photocatalytic oxidation technique in the case of wastewater having a high concentration of chromaticity, turbidity, and organic matter, it is necessary to select an appropriate pretreatment process for the previous stage of the TiO ₂ photocatalyst oxidation process.

In the present invention, the pretreatment step includes a chemical flocculation step for removing suspended suspended solids and an ammonia degassing step for removing ammonia nitrogen. In the chemical flocculation step, a flocculant such as FeCl ₃ can be used to reduce the color, turbidity, and organic matter. This flocculation process is essential for the pretreatment process. The wastewater from which the slurry is removed in this way can be removed by adjusting the pH and then by ammonia degassing by forcibly blowing air. However, the ammonia degassing process may be selectively performed as necessary, and if the ammonia degassing process is not performed in the pretreatment process, it may be performed after the photoacidification process, which is a subsequent process. Individual processes of such a pretreatment process are well known to those skilled in the art and may delete some or all of the pretreatment processes or add additional processes depending on the nature of the wastewater.

1 and 4, the wastewater is introduced into the flow regulating tank (1), is transferred to the coagulation reaction tank (2) through a pump, H ₂ SO ₄ and FeCl ₃ is injected and the reaction pH is maintained at about 3.5 to 4.5 . Wastewater aggregated in the coagulation reaction tank (2) is transferred to the settling tank (3) to stay for a certain time. The sludge in the settling tank 3 is transferred to the dehydrator 11 for final treatment, and the desorbing liquid is transferred to the flow rate adjusting tank 1 for reprocessing. After adjusting the pH to 10.7 or more by injecting NaOH in the pH adjusting tank (4), the wastewater passing through the ammonia degassing column (5) is transferred to the mixing tank (6), and the H ₂ SO ₄ and the reaction aid in the mixing tank (6). Phosphorus H ₂ O ₂ is injected to maintain the pH at 3-4. This is because it shows the most stable efficiency in the pH range.

2 and 3, the wastewater of the mixing tank 6 is introduced into the photocatalytic oxidation reactor 7 by a pump. The TiO ₂ photocatalytic oxidizer needs to be completely mixed with the waste water, and the reactor needs to be developed or selected to have a good turbulence in the reactor for complete mixing.

The photocatalytic oxidation reactor 7 according to the present invention is, for example, a cylindrical reactor, and an ultraviolet lamp is installed vertically at the center of the reactor, and the ultraviolet lamp is installed inside the quartz tube, and the wastewater introduced into the reactor. The powder was set up to form a turbulence such that the powder TiO ₂ and H ₂ O ₂ could be completely mixed. In the photocatalytic oxidation reactor 7, referring to FIG. 3, at least two or more baffles 14 having a hole formed at the center thereof are formed at predetermined intervals, and ultraviolet rays are spaced apart along the circumferential surface of the hole. The quartz tube 13 in which the lamp 12 is built penetrates vertically. The mixed wastewater introduced into the lower portion of the photocatalytic reactor 7 is injected into the gap between the circumferential surface of the hole in the baffle 14 and the outer surface of the quartz tube. The sprayed mixed water may have turbulence formed between the baffle and the baffle to maximize the reaction efficiency. The gap between the circumferential surface of the hole and the outer surface of the quartz tube is preferably 5 to 12 mm to maximize the Venturi effect. The mixed water introduced in this way is discharged through the upper part of the reactor along the →, and the mixed water discharged to the upper part oxidizes and removes contaminants by continuously circulating a plurality of photocatalytic reactors 7. The ultraviolet lamp installed inside the reactor emits ultraviolet rays into the reactor 7, and the emitted ultraviolet rays react with TiO ₂ by chemical interaction with the TiO ₂ catalyst and H ₂ O, oxygen, and H ₂ O ₂ mixed in the wastewater. At the surface of the catalyst produces OH radicals, which are strong oxidizing products. The resulting OH radicals oxidize the toxic, hardly decomposable substances present in the wastewater to be completely decomposed into H ₂ O and CO ₂ . Some of the treated water passing through the photocatalytic oxidation reactor (7) is circulated to the mixing tank (6) by a pump, and some are transferred to the neutralization tank (8) to neutralize the pH to about 6.5 to 8.5. It flows into the catalyst recoverer 9 by this. Optionally, when the ammonia degassing step is not performed in the pretreatment step, the treated water passing through the photocatalytic oxidation reactor 7 is preferably passed through the ammonia degassing column to undergo the subsequent step.

On the other hand, it is necessary to select a lamp suitable for wastewater treatment in the ultraviolet wavelength of 400 nm or less and to determine the properties of TiO ₂ to be used as a catalyst and an optimal injection concentration of selected TiO ₂ . The UV lamp showing the best performance in wastewater treatment was a 1kw lamp having a wavelength of 253.7 to 380 nm, and the size of the UV lamp was determined at about 670 mm, which is easy to manufacture and convenient to transport. Anatase TiO ₂ was effective as a catalyst for the photocatalytic reaction, and the concentration of TiO ₂ was more than 0.1 wt%, preferably 0.1 to 0.5 wt% in consideration of reaction efficiency and economical aspects.

If necessary, the most suitable oxygen for wastewater treatment, H ₂ O ₂ , KBrO ₃ , (NH ₄ ) ₂ S ₂ O ₈ , and / or 2KHSO ₅ to react with ultraviolet rays and TiO ₂ to activate the generation of electrons and holes. Reaction aids, such as KHSO ₄ K ₂ SO ₄ , should be selected and the appropriate dosage of the selected reaction aids should be determined. Dissolved oxygen is not smooth the generation of electrons and holes to the ultraviolet rays and TiO ₂ reaction, or the by the generated electrons and holes are recombined to not serve to actually break down pollutants in correctly investigated bars, H ₂ O Injecting ₂ into the reaction adjuvant not only maintains the formation of electrons and holes smoothly, but also generates OH radicals in the generated electrons and holes to maintain the reaction state to completely oxidize the hardly decomposable organic material.

On the other hand, the injection catalytic material TiO ₂ is collected, followed by re-use is possible because the TiO ₂ development or selection of the catalyst recovery device that can be injection amount to the reactor by circulating device and the recovered TiO ₂ for recovering the TiO ₂ catalyst is required .

The catalyst recovery device 9 used in the present invention is filed in the same manner as the present invention by insisting domestic priority on the patent application No. 98-34180 filed under the name of Lee Hyung Lee, one of the inventors of the present invention. All are included in the present invention. As shown in FIG. 5, the catalyst recoverer 9 according to the present invention has a plurality of drainage holes in a longitudinal oval shape on a hollow fixed shaft 17 fixedly installed on an upper center of the catalyst recoverer 9. And a drainage means for filtering and draining the wastewater supplied to the wastewater treatment tank by installing a clay filter 15 and a collar for fixing the clay filter 15 at a drain hole position; A driving means engaged with the driven gear and the driven gear rotatably mounted on the fixed shaft and driving the driven gear; A cylindrical shape that may include a clay filter section on a fixed shaft, the upper portion of which is fixed to one side of the driven gear is rotated and rotated, the inner circumference of the rotating body is fixed to a predetermined interval clay filter 15 It includes a foreign matter (catalyst) removing means consisting of the scraper 16 to sweep the upper and lower sides of the.

A plurality of disk-type clay filter 15 may be connected about the vertical axis inside the catalytic recovery 9, the pores of the filter can be selectively formed on the order of 0.1 to 1㎛, treated through the photocatalytic oxidation reactor (7) The treated water is separated from the treated water at the outside of the disk-type clay filter installed inside the catalyst recoverer 9. The filtered treated water is discharged through the drain 18 by the internal pressure, and the separated TiO ₂ catalyst accumulates outside the disc clay filter, and the TiO ₂ catalyst continuously rotates on the disc clay filter 15. It is automatically removed by a scraper and accumulated in the slurry state at the bottom of the catalyst recoverer 9. The TiO ₂ catalyst accumulated at the lower end of the catalyst recovery unit is recovered and reused in the mixing tank 6 through the catalyst recovery port 19.

On the other hand, the clay filter 15 is a mixture of 50 to 60% by weight of porous material to 40 to 50% by weight of clay; Primary molding the mixture into a disc shape and then naturally drying the molding; Clay liquid mixed with a porous material having a particle size and pore size that is relatively smaller than the particle size and pore size of the porous material mixed during the primary molding, clay liquid without mixing the porous material, or glaze of a molded product Coating and drying on one side; Calcining the dried molding in a heating furnace at 950-1300 ° C. for 5-12 hours to produce a filter plate; And inserting the reticular metal plate between the filter plate and the plate, and fixing the plate-shaped plate, sealant or adhesive to the end of the filter plate.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.

Preparation Example 1

Preparation of Clay Filters

After dissolving the clay in water, filter out 45kg with a mesh of 100 mesh and prepare 55kg, mix 55kg of diatomaceous earth (Celite 560; Celite Korea), put it in a closed tank, and stir well, and vacuum the inside of the tank using a vacuum pump. By removing the pores produced by the diatomaceous earth inside the body (soil water), the diatomaceous earth and clay were mixed while stirring.

The so prepared body was poured into a disc-shaped plaster mold, and then dried in the shade for 1 day, separated from the plaster mold, and then dried up to 80% in the shade for 1 day. The clay filter thus made tends to bend slightly upward, so that the upper and lower sides are flat and coated on one side. The body to be coated is mixed with a mixture of diatomaceous earth (Celite 500; Celite Korea) in a weight ratio of 4.5: 5.5 in a 100 mesh mesh and stirred well, and then a thin film using a brush on the outer surface of the clay filter. Coated.

After the coating was completely dried again for 2 days in the shade, and calcined at a temperature of about 1200 ℃ to prepare a filter plate. A mesh filter was inserted between the filter plate and the plate, fixed with a c-shaped plate at the end of the filter plate, and finished with silicon to prepare a clay filter.

Preparation Example 2

Using the clay filter manufactured in Preparation Example 1 was prepared a clay filter tank as shown in FIG. In other words, put the O-ring in the support formed on the lower part of the fixed shaft, put the clay filter of Preparation Example 1 on it, assemble in the order of putting the collar with the O-ring inserted on both sides, and laminated 10 filters Next, the collar for length adjustment was put in place and fixed using a nut and a roll nut. In addition, the scraper is fixed to the inner circumference of the rotating body is fixed to the driven gear installed and rotated while being installed on the fixed shaft to be fixed toward the center direction.

Example 1

In this example, the landfill leachate having the same properties as in Table 1 was used. The leachate, which has undergone the usual biological treatment, is introduced into the flow rate adjusting tank, and is transferred to the coagulation reaction tank through a pump to inject 4000 mg / l of H ₂ SO _{4 and} 1300 mg / l of FeCl ₃ to maintain a reaction pH of about 4. The coagulated waste water in the coagulation reactor is transferred to the settling tank for about 90 minutes. The sludge of the settling tank is transferred to the dehydrator for final treatment, and the desorbing liquid is transferred to the flow adjusting tank for reprocessing. After adjusting the pH to 11 by injecting NaOH 4000 mg / l in the pH adjustment tank, the wastewater passed through the conventional ammonia degassing column was transferred to the mixing tank, and H ₂ SO ₄ 4500 mg / l, the reaction aid H ₂ 1000 mg / l of O _{2 is} injected to maintain the pH at about 3.5. Waste water from the mixing bath is introduced into the photocatalytic oxidation reactor (6) as shown in FIG. 3 by a pump and continuously circulated to the desired level. The photocatalytic oxidation reactor is cylindrical with a diameter of 150 mm, uses an ultraviolet lamp of 670 mm, and the gap between the circumferential surface of the baffle hole and the outer surface of the quartz tube is about 7 mm. The ultraviolet lamp emitted a wavelength of 253 to 380 nm, and the implantation concentration of TiO ₂ was 0.1 to 0.2 wt%. The treated water was discharged using the catalyst recovery device (pore of the filter: 0.1-1 μm) of Preparation Example 2, and the TiO ₂ catalyst accumulated at the bottom of the catalyst recovery unit was recovered and reused in a mixing tank. As such, CODCr 289 mg / l was finally achieved through chemical coagulation, ammonia degassing, photocatalytic oxidation, and catalyst recovery. The results are shown in Table 1 below.

Unit: mg / ℓ Item Before treatment Example 1 Leachate Emission Standard COD _Cr 1,394 289 800 BOD 134.3 40.7 70 SS 446.7 8.3 70 T-N 2,342.4 108 - T-P 8.294 0.624 8 NH ₃ -N 1,632 49 100 Chromaticity 1,841 29 300

The present invention is a water treatment method capable of treating up to a legal and environmentally stable level by completely oxidizing toxic, hardly degradable organic substances in waste water. This is because the OH radicals generated by the interaction of the UV lamp with the TiO ₂ catalyst and the oxidation aid convert the material to be treated into CO ₂ and H ₂ O, which are environmentally friendly fully oxidized materials. In addition, there is an economical advantage by recovering the TiO ₂ catalyst participating in the photocatalytic oxidation by the catalyst recovery device and reusing it. According to the above method, the installation area of the device requires less, and all components of the photocatalytic oxidation device are standardized, so that the maintenance is easy. In addition, the existing water treatment process has a compact structure that does not generate a large amount of sludge or secondary waste such as concentrated water, and can continuously operate and remotely monitor and adjust the driver's training and operating personnel. As a result, the economic effect can be expected. In addition, the leachate flow rate fluctuation rate of 5% to 100% can be operated efficiently and modularized, there is an advantage that it is easy to scale up according to the treatment flow rate fluctuation.

Claims (8)

Aggregating and sedimenting the solids of the wastewater to remove them, adjusting the pH of the wastewater from which the solids have been removed, and then pretreating by degassing ammonia; Mixing the wastewater, the powdered TiO ₂ catalyst, and the reaction aid in a mixing tank (6); At least two or more baffles 14 having a hole formed at the center thereof are formed at intervals spaced apart, and the quartz tube 13 having the UV lamp 12 embedded therein is vertically spaced apart along the circumferential surface of the hole. Oxidizing and removing contaminants by introducing the mixed wastewater into a lower portion of at least one photocatalytic reactor (7) penetrating and continuously circulating upwards; By the oxidation of pollutants, filtering the mixture to remove the pressure can be fitted with a scraper 16 to be maintained at 3~5 kg / cm ^2, passed through the catalyst collector 9 is disc-shaped clay filter 15 installed TiO ₂ Obtaining treated water from which is separated; And And continuously removing TiO ₂ accumulated in the clay filter 15 with the scraper 16, and then removing the TiO ₂ continuously into the mixing tank 6 again. Wastewater treatment method using. The method of claim 1, wherein the wastewater is a leachate, a plating wastewater, a dyed leather wastewater, a petrochemical wastewater, a papermaking wastewater, a TNT wastewater, and / or a livestock wastewater. The method of treating wastewater using a photocatalytic reaction according to claim 1, wherein a gap between the circumferential surface of the hole and the outer surface of the quartz tube (13) is 5 to 12 mm. The method according to claim 1, wherein the method further comprises neutralizing the treated water which has been oxidized and removed from the pollutant. 2. The photocatalytic reaction according to claim 1, wherein the ultraviolet lamp 12 is a 1 kw medium pressure mercury lamp, the wavelength of the ultraviolet lamp is 253.7 nm to 380 nm, and the emission length of the ultraviolet lamp 12 is 670 mm. Waste water treatment method. The method of claim 1, wherein the catalyst recovery unit 9 is a plurality of drainage holes are formed in the longitudinal oval in the hollow fixed shaft 17 fixed to the upper center, the clay filter 15 and A collar for fixing it, and a drainage means for filtering and draining the wastewater supplied into the wastewater treatment tank; Drive means engaged with the driven gear and the driven gear rotatably installed on the fixed shaft 17 and driving the driven gear; A cylindrical shape that may include a section of clay filter 15 on the fixed shaft 17, the upper portion is fixed to one side of the driven gear and rotated, and fixed to the inner interval of the rotating body at a predetermined interval And a foreign matter (catalyst) removing means comprising a scraper (16) installed to sweep up and down the upper and lower sides of the clay filter (15). The method of claim 1, wherein the reaction aid is selected from the group consisting of oxygen, H ₂ O ₂ , KBrO ₃ , (NH ₄ ) ₂ S ₂ O ₈ and 2KHSO ₅ KHSO ₄ K ₂ SO ₄ Wastewater treatment method using a photocatalytic reaction. The method of claim 1, wherein the degassing of the ammonia is performed after the photooxidation step.