KR20170065980A - Method for treating circulating water and apparatus for the same - Google Patents

Abstract

The present invention relates to a circulation water treatment method and a circulation water treatment apparatus, and more particularly, to a circulation water treatment method and a circulation water treatment apparatus which are capable of collecting influent water flowing through a scrubber or a cooling tower into a collection tank; And the filtrate is filled in the bottom of the filtration tank filled with a filter medium selected from the group consisting of a floating filter medium, a biofilm filter medium, and a combination thereof, and flows downward through the bottom of the filtration tank, And removing the pollutants from the wastewater adsorbing fluorine-containing flue gas components discharged from a process using various hazardous chemicals such as semiconductors and LCD processes, And how to increase it.

Description

TECHNICAL FIELD [0001] The present invention relates to a circulation water treatment method and a circulation water treatment apparatus,

The present invention relates to a circulating water treatment method and a circulating water treatment apparatus, and more particularly to a circulating water treatment apparatus and a circulating water treatment apparatus which sufficiently remove contaminants from waste water adsorbing fluorine-containing flue gas components discharged from a process using various hazardous chemicals such as semiconductors and LCD processes And how to increase the net exchange rate.

The control of air pollution is difficult to judge as a visible phenomenon when compared with other pollutants, and therefore, the phenomenon of air pollution is neglected and the damage is more serious. Industrial production activities Various kinds of harmful gases and fine dusts generated in each process are varied and it is difficult to apply appropriate control and purification technology due to various effects on the human body. These harmful gases can be mainly classified into odor, volatile organic compounds (VOCs), flammable gas (PFC), toxic gas, etc., and the control and purifying technology has been developed and applied for a long time. However, It is difficult and difficult to increase the maintenance cost.

In the processes using various hazardous chemicals such as semiconductor and LCD process, various harmful chemicals such as hydrochloric acid and hydrofluoric acid are discharged as exhaust gas. Generally, in order to remove such exhaust gas, scrubber, adsorbent Has been used.

The scrubber is classified according to a cleaning method such as wet, dry, adsorption, plasma, and the like. Among them, the wet scrubber is a device that generates droplets by injecting the liquid through the nozzles by applying pressure to the liquid and collecting the suspended dust by colliding or contacting the droplets with the suspended gas flow, Processes using various hazardous chemical substances such as LCD process are aimed at the treatment of various harmful chemical substances such as hydrochloric acid, acid, alkali and Toxic exhaust treatment. Wastewater generated from the wet scrubber of the semiconductor process is concentrated not only harmful chemical substances but also high concentration of F ^- ions in reuse process. However, there is no efficient removal method of these toxic chemicals, especially F ^- ion, in the recycling process of wastewater.

Patent Publication No. 10-2006-0012954, Treatment method of fluorine-containing wastewater (2006.02.09) Patent Publication No. 10-2003-0074424, Method and Apparatus for Treatment of Fluorine-Containing Wastewater (Sep. 19, 2003)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for removing a pollutant from waste water or the like absorbing fluorine-containing flue gas components discharged from a process using various hazardous chemicals such as semiconductors and LCD processes, And to provide a circulating water treatment apparatus. In addition, the present invention relates to a method and a device for improving the recycling rate of circulating water by treating concentrated pollutants, fluorine compounds, suspended substances, etc. of circulating water of a wet scrubber, Water treatment system.

1 is a conceptual diagram showing a configuration of a circulating water processing apparatus 100 according to an embodiment of the present invention. Hereinafter, the present invention will be described with reference to FIG.

In order to achieve the above object, a method of treating circulating water according to an embodiment of the present invention includes: a collecting step of collecting influent water flowing through a scrubber or a cooling tower into a collecting tank; The inflow water from the water collecting tank (10) is supplied to the lower end of the filtration tank (20) filled with any one filter material (22) selected from the group consisting of a floating filter medium, a biofilm filter medium and a combination thereof, And a filtration step of obtaining treated water from which contaminants and suspended matters contained in influent water have been removed.

An agglomeration step may be further included between the collecting step and the filtration step to remove contaminants and suspended substances contained in the influent water.

The coagulation step is carried out by introducing a coagulant containing alum or alum aqueous solution into the water collecting tank 10 and agitating the influent water with the agitating means 12 included in the water collecting tank 10 so that contaminants and suspended substances contained in the influent water And when the flocculant is applied, it is possible to effectively treat inflow water having biological toxicity by containing fluorine at a high concentration.

The alum or alum solution may be a hydroxide of aluminum sulfate, for example, Al ₂ (SO ₄ ) ₃ 14H ₂ O or an aqueous solution thereof. When the alum or alum is used as the flocculant, various hazardous chemicals such as semiconductor and LCD process are used The treatment water of the wet scrubber device for wet-treating the exhaust gas in the process where the hydrofluoric acid gas is discharged, and the like, are excellent in efficiency when treated as the influent water of the present invention.

The alum used as the flocculant may be injected into the influent water in an amount of 1 to 1.5 g / liter and may be injected so as to be contained in an amount of 1.16 to 1.31 g / liter. When the alum is applied to the agglomeration step in the range of the above content, the maximum treatment efficiency can be obtained with respect to the use amount of the flocculant. Especially, the biofilm filter medium which can be applied in the subsequent filtration step can be efficiently treated with circulating water Method can be applied.

It is preferable that the pH is controlled within a predetermined range while monitoring the pH change of the influent water in the course of the flocculation step. Specifically, it is preferable that the pH of the influent water is controlled to be 5.5 to 9.0, It can proceed efficiently. In particular, controlling the flocculation step while controlling the pH of the influent water to 5.5 to 8.0 can effectively remove the excess amount of fluorine contained in the influent water and effectively remove the gaseous contaminants from the wet scrubber of the fluorine-containing flue gas, It has an excellent effect on the treatment of inflow water containing an excessive amount of fluorine such as absorbed wastewater.

The pH may be adjusted by adding a pH adjusting agent. Examples of the pH adjusting agent include, but are not limited to, hydrochloric acid, sodium hydroxide, and the like.

In particular, the alum can be injected into the influent water in an amount of 1 to 1.5 g / liter, and in the flocculation step, the pH of the influent water can be maintained at 5.6 to 8. In this case, It is possible to remove more than 80% of the fluorine or to efficiently remove the fluorine to be 3 ppm or less.

The agglomeration step may be carried out with agitation using agitation means, and the agitation may be carried out at the initial stage of the agglomeration stage, the slow agitation stage at the intermediate stage, and the agitation stage without the agitator. Specifically, the rapid stirring may be a process of stirring at 100 to 200 rpm, and the slow stirring may be a process of stirring at 20 to 80 rpm. The rapid stirring, the slow stirring, and the precipitation may be repeated in sequence. When the agitation is carried out in the agglomeration step, the process in which the contaminants and floating substances in the inflow water are formed by the flocculant by the flocculant promotes the process, and the flocculant collides with each other to form a larger flocculant and facilitate precipitation The efficiency of progress of the agglomeration process can be improved when agitation is carried out in the agglomeration process, and it is possible to facilitate the removal of contaminants or suspended substances by the filter material in the subsequent filtration step.

The treated water having passed through the filtration step can be reused as the pollutant absorption water of the scrubber or the cooling water of the cooling tower.

Fluoride ions meet with calcium ions and form precipitates, which cause nozzle clogging due to circulating water. However, the circulating water treated by the method of treating the circulating water according to the present invention can remarkably lower the fluorine concentration in the circulating water, so that the clogging of the nozzle due to such precipitation can be remarkably reduced, It is possible to increase the circulation rate and improve the convenience of maintenance of the circulating water system, thereby reducing the processing cost.

In addition, it is possible to remove contaminants such as fluorine ion content in the treated water below the level suitable for the environmental standard, so that even when the treated water treated by the method of the present invention is discharged, it can be discharged without any additional pollutant removal treatment.

The circulating water treatment apparatus 100 according to another embodiment of the present invention includes a water collecting tank 10 in which influent water collected through a scrubber or a cooling tower is collected; A connection part 16 for allowing the inflow water of the water collecting tank 10 to flow downwardly from the lower end of the filtration tank 20; And a filtration tank (20) which is filled with a filter medium (22) selected from the group consisting of a floating filter medium, a biofilm filter medium and a combination thereof to remove contaminants and suspended matters from the inflow water introduced by the connection unit ).

The water collecting tank 10 may further include an agitating means 12 for agitating the inflow water collected in the water collecting tank and a chemical loading port (not shown) for administering a flocculant, a flocculant and a pH adjusting agent to the inflow water.

Further, the water collecting tank 10 may further include a measuring unit (not shown) for monitoring the characteristics of inflow water therein. The measuring unit may measure the pH of the influent water, the content of fluorine ions contained in the inflow water, It may be monitoring.

The filtration tank 20 further includes a recycling connection portion (not shown) for connecting the treated water to the pollutant absorption water of the scrubber or the cooling water of the cooling tower, or a discharge portion (not shown) for discharging the treated water to the outside .

The water collecting tank (10) and the filtration tank (20) may further include a sediment outlet (not shown) at the lower end thereof.

The structure including the water collecting tank 10, the filtration tank 20, and the connecting portion 16 can be formed as a single module and can be formed into a cartridge. If necessary, the water is installed in a conventional wet scrubber device or a cooling tower, can do.

The filter medium 22 to be filled in the filtration tank is also filled in an inner space formed by an outer wall (not shown) of the filtration tank and an inner wall (not shown) positioned in contact with the outer wall and detachable from each other. And may have a cartridgeized filtration tank 20 configuration to replace the filled inner wall structure itself when the filter medium 22 needs to be replaced.

The circulating water treatment method and the circulating water treatment apparatus of the present invention provide a treatment method of circulating water capable of sufficiently removing suspended substances and contaminants, thereby reducing occurrence of clogging in the scrubber even if the circulating water rate is increased And it is possible to efficiently treat the circulating water through the filtration process with or without the coagulant injection, without necessitating any additional process such as sedimentation tank or flotation tank by the generation of sludge, Can be improved and the cost can be reduced. In addition, a small-scale circulating water treatment device, such as a conventional slide cover device, can be easily installed and replaced if necessary, which is very advantageous in terms of economy and maintenance.

1 is a conceptual diagram showing a configuration of a circulating water processing apparatus according to an embodiment of the present invention;
FIG. 2 is a graph showing the results of evaluating fluorine removal efficiency of treated water according to the pH condition of influent water in Examples of the present invention. FIG.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

The present invention relates to a system for effectively treating and removing influent pollutants, fluorine compounds, suspended solids (SS) and the like, such as scrubber wastewater having a high fluorine concentration, thereby improving the existing flocculation and filtration processes And it can be easily installed in existing scrubber devices. It can effectively flocculate pollutants and fluorine compounds concentrated in wastewater at high concentration by using alum and filter SS which causes turbidity, And to reduce the cost by increasing the net exchange rate.

In the process using various hazardous chemicals such as LCD process, various harmful chemical substances such as hydrochloric acid and hydrofluoric acid are discharged as exhaust gas. In order to remove such exhaust gas, a scrubber is generally disposed at the final stage. .

The most common of these purifying technologies is scrubber. This system collects high-purity fine particles in gas by using liquid (usually water), and it is most widely used because it can remove pollutants and expect a relatively high collection efficiency .

This scrubber system usually requires 2 liters of water per minute at a treatment capacity of 1 cmm (cm ³ / min), the capacity of scrubber used in large-scale factories is 500 to 1500 cmm, 4320 tons are required.

In order for the gaseous pollutants to be absorbed and processed, it is necessary to contact with the absorbing liquid. In order to increase the treatment efficiency, the contact area with the absorbing liquid must be wide and the contact time must be long. In order to satisfy these two requirements, a nozzle is placed in the scrubber constant, and the absorption liquid is made into a small droplet so that the surface area of the absorption liquid is increased by filling the filling solution into the inside of the scrubber, And the surface area at which the gas contacts.

Gaseous contaminants are dissolved in the absorbing liquid from the surface of the absorbing liquid to form an ionic form. The longer the contact area and the longer the contact time, the lower the pollutant concentration of the gas. However, the higher the ion concentration of the absorption liquid, the more the process efficiency becomes lower because it does not melt. Therefore, the concentration of contaminants in the absorption liquid is lowered, and the water is continuously supplied to the lower part of the scrubber to replenish the absorption liquid which goes out with the gas or evaporates, and the absorption liquid is poured onto the upper part of the scrubber using a pump.

If it is not simply treated with water, or if the concentration of the absorption liquid becomes too high, another compound is added to the absorption liquid to react and remove gaseous contaminants. (NaOH), potassium hydroxide (KOH), sodium carbonate (Na ₂ CO ₃ ), and limestone. The water supplied to the scrubber is also used to maintain an appropriate pH.

Since the scrubber system requires a large amount of water in the process, more than 90% of the water used in the process is reused (circulating water). The above method can reduce the amount of water used, but due to the increase of the number of reuses and the increase of the load of the floating matters and pollutants, the nozzles for spraying the water and the packing are blocked, , And periodic parts replacement costs and labor costs are used. Therefore, the inventors of the present invention have recognized that there is a need for a new technique capable of preventing the clogging of the inside of the scrubber and thereby maintaining the treatment efficiency by reducing the load of suspended solids (circulating water) and pollutants in the reusable water, .

In order to solve the above-mentioned problems, the present invention reduces the use amount of water by physically, chemically and biologically treating the biofilm treatment apparatus using a cartridge type biofilm treatment apparatus capable of reducing the load of suspended substances and contaminants, In order to reuse the circulation water generated in the scrubber, the problem of reducing the scrubber treatment efficiency by reducing the clogging of the scrubber due to suspended substances and contaminants is solved and a technique and apparatus for maintaining the stable treatment efficiency of the scrubber have been developed.

Specifically, a cartridge type biofilm treatment apparatus is used to physically and physically treat suspended matter and contaminants and then reuse them. When the inflow water is introduced in an upward flow mode after filling the filter media, A method is used in which the solids contained in the influent water are filtered through the filter media while flowing through the filter media, and the coagulant is injected in the pre-filtration step according to the conditions of the influent water to remove the coagulated and suspended material through the biofiltration membrane, And a wastewater treatment system for improving the efficiency by using the wastewater as a circulation water is one of the major technical constructions of the present invention.

The present technology of the present invention sets the principle of solving the problem of solving the circulating water for recycling of the circulating water as the first priority and resolves the scrubber treatment efficiency caused by the clogging of the scrubber due to the suspended substances and contaminants The technology of reducing circulating water by removing coagulated suspended matter contaminants through the biofilm membrane was developed. By applying the technique of the present invention, the facility cost and the maintenance cost can be reduced by 30% and 40%, respectively, as compared with the conventional process.

In addition, since an additional process of the settling tank or flotation tank due to the occurrence of the sludge, which was a problem in the existing method for removing the scrubber solids, is not further required, when the load of the solid is small, The management convenience can be increased and the economical efficiency can be improved.

The circulating water treatment device for the circulating water treatment and reuse supply for implementing the scrubber system injects an inorganic coagulant according to the characteristics of the circulating water to coagulate the pollutant and effectively removes the solids through the biofilm filter media, It is a device that can enhance the recycling rate of circulating water used in the scrubber and reduce the load of wastewater flowing into the wastewater treatment plant and stability of operation management at the same time.

The function of each reaction vessel with reference to FIG. 1 will be described below.

FIG. 1 is a view showing a state where a circulating water generated from a scrubber system is introduced into a water collecting tank (coagulation tank) 10 to coagulate and remove contaminants from the coagulant, and then, in a filtration tank (filtration tank) Which is a water treatment system capable of reusing the circulating water or reducing the pollutant load of the treated water and discharging it to the wastewater treatment plant. More specifically, it is a water treatment system in which the influent scrubber circulating water is introduced, A flocculation tank 10 for flocculating the pollutants by forming a flocculate and introducing a pH adjusting agent for optimum flocculation and a flocculant tank 10 located at the rear end of the flocculation tank 10 and containing sludge adsorbing contaminants, The solid material is separated using filter medium or biofilm filter media, and the treated water is sent back to the scrubber circulation pipeline to be circulated It consists of a filtration tank (20, filtration tank) having the purpose of releasing engagement or sent to the wastewater treatment plant.

The circulating water generated in the scrubber flows into the water collecting tank (10, coagulation tank), and the liquid inorganic coagulant is added to the water collecting tank (10) according to the circulating water characteristic. At this time, in the water collecting tank 10, floc is formed by the inorganic coagulant, and the stirring is carried out using the counter-rotating means 12 at a proper speed, so that the contaminants are adsorbed on the immersion water, The material can be separated and removed. On the other hand, when the alkalinity is consumed by the acid generated by the inorganic flocculant, a chemical such as salt or acid may be injected to compensate for the alkalinity consumed or to maintain an appropriate pH for the flocculation reaction.

Contaminants and solid matter aggregated by the condensate are captured and oxidized and decomposed in the water by filtration media (filtration tank) (20, filtration tank) and filtration media (22, filter media) 22), and the solid material is removed by surface adhesion. When a biofilm is formed in the filtration tank 20 in the filtration tank 20, various microorganisms that are responsible for organic oxidation, nitrification and denitrification in the biofilm adhere to the surface of the filtration tank 22 to form a viscous and jelly-like structure The microorganisms adhered to the filtration (22) aggregate and decompose the organic material to obtain the energy required for cell synthesis, and cell proliferation is performed.

When the load of the pollutant or solid matter is small, the solid matter is removed by the filter paper 22 including the biofilter media through the filtration tank 20 (filtration tank) with or without passing through the collecting tank (coagulation tank) So that the process steps can be simplified and the circulation number can be used more efficiently.

< Example >

1) Experimental method

The following experiment was carried out by applying the washing water generated from the scrubber cleaning device during the semiconductor process of S Company as the influent water, and the characteristics of the washing water are shown in Table 1 below.

pH Turbidity F ^- (-) (NTU) (mg / L) 3.2 1.86 57.0

The flocculant used in the experiment was an aqueous solution in which alum (Al ₂ (SO ₄ ) ₃ .14H ₂ O) was diluted to 5 wt%. The experiment was carried out by varying the amount of coagulant, the pH, and the stirring speed after filling 1L of the influent into 5 beakers. The flocculant dosage was varied from 1 to 10 mL, and the influent treatment efficiency was experimentally adjusted while the pH was adjusted to 4 to 10. The pH adjustment was applied by titration with 0.5N HCl and 0.5N NaOH, and the pH was adjusted continuously by injection immediately after rapid mixing. In the case of the stirring speed, stirring was carried out rapidly at 150 rpm for 1 minute and at 50 rpm for 20 minutes. After 30 minutes of stirring, the respective fluorine removal rates were compared.

Toxicity of the treated water was measured using Daphania magna Straus , a test organism. The daphnia were added to the test water diluted in various ratios and observed for 24 hours. The concentration of the sample causing 50% ₅₀ ) was determined and the ecotoxicity value (TU) was calculated by unit conversion.

2) Experimental results

Fluoride removal rates were 42%, 70%, 83%, and 94%, respectively, when the pH of the influent water was kept constant at 8 before and after the coagulant injection and 1, 3, %. Therefore, the removal efficiency of the coagulant injection amount was found to be most effective at about 4 mL per liter of influent water.

Fluoride removal rates were 4%, 54% and 94%, respectively, when the pH of each influent was fixed at 4, 5, 6, 8, and 10, respectively, , 80% and 16% respectively. When the removal efficiency was 94%, it was found that the concentration of fluorine in the treated water was 0.7 ppm, which was lower than the limit of 3 ppm of the wastewater discharge standard in the clean area (see FIG. 2).

In the ecotoxicity test using daphnia, the influent water showed 12.57 TU ecotoxicity but the treated water decreased to TU 0.

The method for treating circulating water according to the present invention, specifically, the system for recycling the scrubber water, is a method of removing circulating water generated from a scrubber system through a circulating water treatment apparatus of the present invention to remove clogging substances and suspended substances, Therefore, it is possible to prevent frequent parts replacement and deterioration of treatment efficiency, and to improve the reuse rate and efficiency of the scrubber circulation water, thereby greatly reducing the maintenance cost.

The treated recycled water that is not reused flows into the wastewater treatment plant, which can provide stability and economy in operation management. It can be applied to reuse of cooling tower water as well as scrubber facilities. Do.

In addition, since the circulating water treatment apparatus of the present invention does not require a large space, it is useful for introducing it into a conventional scrubber facility, and additionally installing a sedimentation tank or flotation tank due to the occurrence of sludge, which has been a problem in existing methods for removing solid matter This technology is unnecessary and easy to manage and operate by simplifying and automating the process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

The water collecting tank (10)
The connection section (16) the filtration tank (20)
Filter medium (22) Circulating water treatment device (100)

Claims (7)

Collecting the influent water flowing through the scrubber or the cooling tower into the collecting tank; And
The filtrate is filled in the bottom of the filtration tank filled with any one of the filtration media selected from the group consisting of a pore filter, a floating filter media, a biofilm filter media, and a combination thereof, A filtration step of obtaining the removed treated water;
Gt; a &lt; / RTI &gt; circulating water. The method according to claim 1,
Wherein an agglomeration step is further included between the collecting step and the filtration step,
Wherein the flocculating step is a step of injecting a flocculant containing alum or alum solution into the water collecting tank and agitating the influent water with agitation means included in the water collecting tank to form a flocculant contained in the inflow water, Method for the treatment of circulating water. 3. The method of claim 2,
Wherein the flocculating step is carried out by adjusting the pH of the influent water to 5.5 to 9.0 by adding a pH adjusting agent. The method according to claim 1,
Wherein the treated water having passed through the filtration step is reused as pollutant absorption water of a scrubber or cooling water of a cooling tower. A water collecting tank for collecting inflow water through a scrubber or a cooling tower;
A connection part for introducing the inflow water of the water collecting tank to pass through the lower end of the filtration tank in a downward direction; And
A filtration tank filled with a filter medium selected from the group consisting of a floating filter medium, a biofilm filter medium, and a combination thereof to remove contaminants and suspended matters from inflow water introduced by the connection unit. . 6. The method of claim 5,
Wherein the water collecting tank further comprises agitation means for agitating the influent water collected in the water collecting tank and a chemical inlet for administering the flocculant or the flocculant and the pH adjusting agent to the influent water,
Wherein the filtration tank further comprises a recycling connection portion for connecting the treated water to the pollutant absorption water of the scrubber or the cooling water of the cooling tower, or a discharge portion for discharging the treated water to the outside. 6. The method of claim 5,
Wherein the circulating water processing apparatus is constructed in a module form including the water collecting tank, the filtration tank, and the connection portion.

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