KR20090083141A - Method for removal of ammonia from waste water - Google Patents

Abstract

A method for removing ammonia of wastewater is provided to remove an ammonia component contained in leachate with low cost by using a physical chemical mode with cyclone. A method for removing ammonia of wastewater includes the following steps of: collecting the wastewater containing the ammonia in a storing tank(200); fining the wastewater with the air flowed from the wastewater; inflowing a compound of the wastewater and the air into a removal column(600); discharging ammonia gas to the outside; collecting the wastewater to a discharge tank(800); and discharging the collected wastewater according to ammonium concentration or restoring the wastewater to the storing tank.

Description

Method for removal of ammonia from waste water}

The present invention relates to a method for removing ammonia from wastewater. In particular, the ammonia component contained in the wastewater can be separated from the wastewater in a physicochemical manner using the cyclone method and the basicity of the leachate so that the ammonia gas can be easily removed at low cost. An apparatus for treating ammonia in wastewater.

In general, leachate from waste landfills vary in quality and quantity according to various environmental variables such as type, quantity, landfill period, topography, method, rainfall, and climatic conditions. Advances in technology have resulted in more diverse and complex leachate emissions from landfills of new synthetic wastes.

In the existing waste landfill, the leachate treatment method is mostly biological treatment using activated sludge to treat only organic substances for BOD and COD, so it is hard to treat nitrogen contained in high concentration in leachate. to be.

Ammonia-containing leachate is discharged from inorganic industrial landfills. In particular, the coke manufacturing process of the steel mill is carried out in a reducing atmosphere, the washing water generated in the process of wet cleaning the generated gas contains a lot of ammonia.

The nitrogen content contained in the existing wastewater has an adverse effect on the ecosystem such as eutrophication of seawater during discharge, and the regulation on the total nitrogen concentration of treated water is gradually tightened.

Nitrogen components in various industrial wastewater exist in the form of organic nitrogen and inorganic nitrogen, which are referred to as total nitrogen. Mineral nitrogen is again divided into ammonia and nitrate nitrogen (NOx-N).

In particular, inorganic nitrogen can cause color and odor of industrial wastewater, cause harmful gases and eutrophication, and directly increase the chemical oxygen demand (COD) and biochemical oxygen demand (BOD) of the wastewater. do.

However, ammonia in the inorganic nitrogen is released as it remains in the waste water at high concentrations. Therefore, in order to comply with legal emission limits in industrial wastewater treatment, the removal of mineral nitrogen from the total nitrogen content in the wastewater, in particular the removal of ammonia, is key.

Nitrogen removal in existing wastewater includes biological and chemical methods.

Conventional biological treatment methods treat nitrogen inflow into industrial wastewater in a two-step process: nitrification and denitrification. That is, in the nitrification step, ammonia and organic nitrogen are converted to nitrate nitrogen by aerobic nitrification bacteria. In the denitrification step, denitrification bacteria which nitrate nitrogen instead of oxygen as an electron acceptor in the absence of oxygen oxidize the organic matter and nitrate. Nitrogen is reduced to nitrogen gas and released into the atmosphere.

In addition to these methods, other biological methods include algae culture, aquatic plant cultivation, and microbial nitriding.

The most common chemical method is chlorine treatment using chlorine gas, which is effective in removing ammonia while killing pathogens at the final stage of water treatment. However, in the chlorine treatment method, since trihalomethane, which is a carcinogen, may be generated during disinfection, a separate equipment for controlling the inhibition of generation of such carcinogens is required. In addition, chlorine gas must be handled with great care, and a separate neutralization tank should be provided to neutralize any leakage of chlorine gas during operation.

In addition, techniques for treating wastewater containing ammonia include breakthrough chlorine injection, ion exchange, and air stripping, which are physical and chemical methods.

The breakthrough chlorine injection method is limited to low concentration ammonia-containing wastewater due to the high maintenance cost, and the ion exchange method is economical when applied to low concentration wastewater and also causes secondary environmental problems such as regeneration wastewater during resin regeneration. There are many difficulties in operation.

The degassing method is suitable for the treatment of high concentration ammonia-containing wastewater, which includes a cooling tower method and an underwater aeration method.

In the case of the cooling tower method, the air is moved upward by a blower installed in the upper part, and the waste water falls to the lower part and is accumulated by the impingement plate. At this time, the ammonia in the waste water is discharged to the atmosphere while the air and the waste water contact each other.

However, this is not suitable for use as a main treatment facility in actual wastewater treatment because the ammonia removal efficiency has a large seasonal variation and the degassed ammonia gas is released into the atmosphere to generate secondary pollution. In the case of the submerged aeration system, a diffuser is installed in the water to supply a high-pressure air to a blower and aeration to release ammonia in the wastewater to the atmosphere by turbulence.

In addition, the air pollution problem caused by ammonia gas, as in the cooling tower method and blower operation takes a lot of power is inefficient.

However, conventionally, biological methods are mainly adopted because of the degassing efficiency and economic efficiency of the above methods, and the biological method is composed of processes using aerobic, anaerobic and breathable bacteria.

The nitrogen removal method by biological method requires a large site and high operating technology according to the facility, and the treatment efficiency changes greatly according to the change of external conditions, so that there is a risk of exceeding the emission limit, Since the nutrients are ingested and removed together with the nitrogen component in the wastewater, there is a problem in removing ammonia contained in the inorganic wastewater having less nutrients.

Therefore, nutrients must be replenished in order to treat ammonia in wastewater containing less nutrients, and thus, a cost for removing ammonia is increased.

The present invention has been proposed in view of the above-mentioned problems, and an object thereof is to easily remove ammonia contained in leachate at low cost in a physicochemical manner using ammonia-containing leachate. In addition, the present invention provides a method for removing ammonia from wastewater, which can greatly reduce the space required for the treatment of wastewater and enable the treatment of large-scale wastewater.

The present invention for achieving the above object is the step of collecting the waste water containing ammonia component in the storage tank,

Miniaturizing the wastewater collected in the reservoir with air introduced from the outside;

Inducing the mixture of wastewater and air in a cyclone manner and introducing the wastewater and air into the removal tower so as to be divided into ammonia gas and wastewater by a difference in specific gravity;

Sucking the ammonia gas introduced into the removal tower at a vacuum negative pressure and discharging the ammonia gas to the outside;

Directing the wastewater introduced into the removal tower to the lower side and collecting the wastewater in the discharge tank and then discharging the wastewater to the outside according to the ammonia concentration of the collected wastewater, or returning the wastewater collected in the discharge tank to the storage tank again. Characterized in that.

Measuring the hydrogen ion index of the waste water in the step of collecting the waste water in the reservoir and supplying an alkaline solution to maintain the alkaline hydrogen ion index.

The method may further include stirring the inside of the reservoir after supplying the alkaline solution in the step of maintaining the hydrogen ion index of the waste water in an alkaline state.

In the step of miniaturization by mixing the waste water with the air introduced from the outside is to refine the waste water and air into a mixture through a mixing tube in the form of a venturi tube.

In the step of miniaturizing by mixing the waste water with the air introduced from the outside, it is preferable that the minute inflow of the wastewater relative to the minute inflow of the air is 0.02 to 0.002 L / m 3.

The lower portion of the removal tower is formed in a straight line different from the cylindrical upper portion to prevent backflow of the wastewater in the process of inhaling the ammonia gas by the vacuum negative pressure.

The present invention relates to a method for removing ammonia from wastewater, which enables to easily remove ammonia from wastewater at low cost by a physicochemical method using a cyclone. Since it can be easily separated, the ammonia component of the leachate lacking nutrients also has a useful effect of being able to be treated.

In addition, the present invention has the advantage that the wastewater containing the ammonia component has a strong basicity and the liquid droplets of the wastewater can be refined to improve the removal efficiency of the ammonia component in the wastewater.

And even in the wastewater containing the suspended solids, it is possible to continuously remove ammonia components for a long time.

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

The ammonia removal method of the wastewater according to the present invention will be described with reference to FIGS. 1 to 4, where the wastewater containing the ammonia component is collected in the storage tank 200 (S1), and the hydrogen of the wastewater collected in the storage tank 200. After measuring the ion index (PH) and supplying an alkaline solution to maintain an alkaline hydrogen ion index when it is not alkaline (S2), waste water having an alkaline hydrogen ion index is supplied in the form of a venturi tube through a supply pump (32). In the process of mixing with the air flowing from the outside by supplying the inside of the mixing tube 510 to refine the liquid droplets of the waste water (S3), and the mixture of the waste water and air is refined by the specific gravity difference of the waste water and ammonia gas in a cyclone method Induced to the inside of the removal tower 600 to be separated (S4), the separated ammonia gas is sucked into the vacuum negative pressure of the blower 750 and discharged to the outside (S5), the separated waste water of the removal tower 600 Including the step (S6) to be guided to the lower and discharged to the outside according to the ammonia concentration of the collected wastewater after the collection in the discharge tank 800 or to return the wastewater collected in the discharge tank 800 back to the storage tank 200 (S6) Is done.

Preferably, maintaining the hydrogen ion index of the wastewater in the storage tank to be alkaline after measuring the hydrogen ion index of the wastewater in the storage tank 200 using the ion index measuring device 240, If the alkaline solution is not basic, the alkaline solution is supplied into the reservoir 200, followed by stirring using the stirrer 250 to quickly and evenly mix the alkaline solution and the wastewater in the reservoir 200.

In addition, it is preferable that the storage tank 200 has a structure in which a partition 210 is installed so as to divide a site where waste water is supplied and discharged to both sides in order to increase the residence time so that the alkaline solution is evenly mixed with the waste water.

The cyclone guide pipe 550 has a function of guiding the flow direction of the mixture conveyed from the mixing pipe 510 to be rotatable, and has a structure formed to have a curvature for this purpose.

The supply device of the alkaline solution is a solution supply pipe 310 and a solution supply pipe 310 which connect the alkali solution tank 300 filled with the alkaline solution, the alkali solution tank 300 and the storage tank 200 to be a transport passage of the alkaline solution. And an alkali control valve 22 arranged to open and close the solution supply pipe 310 according to the hydrogen ion index measured from the ion index measuring device 240.

As the alkaline solution, calcined lime (Ca (OH) 2) and sodium hydroxide (NaOH) may be employed, but are not limited thereto.

At this time, it is preferable to maintain the hydrogen ion index of the waste water in the reservoir 200 to 9 to 12, which is a base proton when the ammonia ion and the hydroxide ion has a chemical reaction with ammonia and water as shown in the following formula (1) The stronger the base, the stronger the base, and the stronger the base, the higher the ability to dissociate in aqueous solution to release the hydroxide ions, thereby depriving protons from the solvent, water (H₂O), to release the hydroxide ions (OH-). This is because the higher the basicity, the higher the amount of chemical reaction of converting ammonia ion (NH₄ +) and hydroxide ion into ammonia (NH₃) and water.

NH₄ + + OH- ↔ NH₃ + H₂O

On the other hand, in order to facilitate the separation of ammonia from the wastewater in the removal tower 600, the smaller the liquid droplets have the same effect as the basicity rise, but in the case of the pressure conditions, the lower the pressure inside the removal tower 600 as opposed to the glass This results in an inverse correlation.

This is because smaller droplets increase the surface area where hydroxide ions are in contact with ammonia ions. On the contrary, the higher the pressure, the more ammonia gas is brought into contact with the wastewater, thereby increasing the amount of reaction to react with ammonia ions.

Therefore, in order to reduce the droplets of liquid, the mixing tube 510 in the form of a venturi tube has a process of miniaturizing the liquid droplets of the wastewater, which applies Bernoulli's principle.

That is, as the mixture is introduced into the mixing tube 510 as a mixture of air and wastewater, the liquid droplets of the wastewater are finely broken while passing through the narrow inlet of the venturi tube.

The structure of the mixing pipe 510 is as shown in Figure 3, the waste water inlet pipe 230 is connected to the inlet side of the venturi tube form through the waste water inlet pipe 230 in the waste water tank 200 in accordance with the inflow of air It has a structure flowing into the mixing tube 510.

At this time, the outside air is sucked through the air supply pump 420 is supplied into the mixing pipe 510 through the air inlet pipe 410, employing an air flow regulator 430 to adjust the inflow of outside air do.

In addition, the wastewater is supplied through a wastewater supply pump 32 disposed in the wastewater inlet pipe 230.

Subsequently, the mixture of wastewater and air refined through the mixing tube 510 is connected by the cyclone induction tube 550 having one end connected to the mixing tube 510 and the other end communicating with the inside and the end of the elimination tower 600. Guided to the removal tower 600 in a cyclone manner.

As the mixture is induced in a cyclone manner, the ammonia component contained in the liquid droplets of the wastewater is gasified into the ammonia as it is separated from the wastewater, and the gas-liquid separation is performed by specific gravity as it flows into the removal tower 600.

That is, the liquid wastewater has a property of turning along the inner circumferential surface of the removal tower 600 by centrifugal force, and ammonia, which is a gas, is disposed at the upper 610 because the internal pressure of the removal tower 600 maintains a vacuum negative pressure. Since the gas is discharged to the outside through the gas collecting pipe 650 and the gas discharge pipe 710, the gas-liquid separation is made.

In addition, the blower 750 is disposed in the gas discharge pipe 710 and has a function of maintaining the pressure inside the removal tower 600 at a vacuum negative pressure, the gas flow rate in the gas discharge pipe 710 to control the discharge flow rate of ammonia gas The regulator 730 may be further provided.

In addition, the removal tower 600 is gas-separated, the upper portion 610 is configured in a cylindrical shape to assist the turning of the waste water induced by the cyclone method, the intermediate portion 620 is configured in a columnar shape narrowing toward the lower, The lower portion 630 is configured in the form of a straight tube with a narrow inner diameter.

Since the internal pressure of the elimination tower 600 maintains the vacuum negative pressure, the lower part of the waste water becomes solid by forming a straight line having a long length, so that the waste water flows back toward the gas discharge pipe 710 located at the upper part by air pressure. To prevent it.

Subsequently, the wastewater accumulated in the lower portion of the removal tower 600 flows into the discharge tank 800 at the lower side and is collected, and the hydrogen ion index of the wastewater collected into the discharge tank 800 is transferred to the ammonia concentration measuring instrument 805. When the measured and ammonia concentration is satisfactory, it is discharged to the outside, and when the ammonia concentration is high, the wastewater in the discharge tank 800 is returned to the storage tank 200 side again.

The process of discharging or returning the wastewater in the discharge tank 800 to the outside may be discharged to the outside through the wastewater discharge pipe 810 or returned to the storage tank 200 by the wastewater discharge pump 14.

At this time, the wastewater discharge valve 820 disposed on the wastewater discharge pipe 810 and the wastewater return valve 34 disposed on the return path are selectively determined to discharge and return the wastewater, respectively, and the wastewater discharge valve 820. And the opening and closing operation of the waste water return valve 34 have opposing operations.

That is, when the ammonia concentration of the wastewater is high, the wastewater discharge valve 820 receiving the signal of the ammonia concentration measuring instrument 805 is closed and the wastewater return valve 34 is opened to return the wastewater to the storage tank 200. On the contrary, when the ammonia concentration in the wastewater is lean, the wastewater discharge valve 820 is opened and the wastewater return valve 34 is closed, so that the wastewater is discharged to the outside through the wastewater discharge pipe 810.

The flow rate at which the wastewater returns into the reservoir 200 is adjusted by the wastewater return valve 34 disposed on the return path of the wastewater.

In addition, when the flow rate of the wastewater returned to the reservoir 200 is small, the wastewater is supplied using the wastewater transfer pump 16 disposed in the wastewater supply pipe 110.

On the other hand, the inlet ratio (gas-liquid ratio) of the wastewater and air for separation of ammonia in the removal tower 600 is preferably a ratio of wastewater to air 0.002 ~ 0.02L / ㎥.

Gas-liquid ratio shows the inflow of wastewater per minute (ℓ / min) with respect to the inflow of air per minute (m <3> / min).

In contrast, the liquid ratio represents the inflow of air per minute to the inflow of waste water. For example, the liquid ratio 100 means that the amount of inflow of air per minute for treating wastewater inflow (1 L / min) is 100 m 3 / min.

This is because when the amount of wastewater to air is less than 0.002 l / m 3, the wastewater treatment efficiency is lowered, and when it exceeds 0.02 l / m 3, the efficiency of refining the liquid droplets of the waste water may be lowered.

In addition, the speed (V) of the mixture flowing into the removal tower 600 is preferably 10 ~ 30m / sec, if the speed is too fast, there is a risk that gas-liquid separation is insufficient, when the speed is too slow separated This is because the ammonia component may dissolve again in water and react with ammonia ions.

Example

In Examples 1, 2, 3, 4, and 5 of the present invention, different ammonia ratios are given and the concentrations of ammonia contained in the waste water are respectively shown when the number of return operations of the waste water is applied 1 to 5 times.

After the alkaline solution was added to the inorganic wastewater having an ammonia concentration of 1015 ppm and the hydrogen ion index of 8.6, the hydrogen ion index was adjusted to 9.1, and then the ammonia component in the waste water was removed in the manner described above.

Ammonia concentration Expenses One 2 3 4 5 Example 1 52 816 678 589 451 324 Example 2 109 709 578 412 305 213 Example 3 215 670 431 314 161 109 Example 4 312 602 341 199 87 27 Example 5 411 511 291 102 56 11

As described above, as described above, the gas-liquid ratio is 0.002 to 0.02ℓ / m 3, on the contrary, the liquid-liquid ratio is preferably 50 to 500, and as the number of times increases, the concentration of ammonia in the wastewater gradually decreases.

1 is a flow chart sequentially showing a method for removing ammonia from wastewater according to the present invention.

Figure 2 is a schematic diagram showing the configuration of a removal apparatus for realizing a method for removing ammonia of wastewater according to the present invention.

Figure 3 is a cross-sectional view showing a part of the configuration of the mixing tube of the present invention.

Figure 4 is a perspective view showing a connection structure of the present invention cyclone guide pipe and the removal tower.

Explanation of symbols on the main parts of the drawings

200: reservoir 510: mixing tube

600: removal tower 610: upper part of the removal tower

630: lower part of the removal tower

800 discharge tank

Claims (6)

Collecting the wastewater containing the ammonia component into the storage tank 200; Miniaturizing the wastewater collected in the reservoir 200 with air introduced from the outside; Inducing the mixture of the waste water and air in a cyclone manner to flow into the interior of the removal tower 600 to be separated into ammonia gas and waste water by the difference in specific gravity, Sucking the ammonia gas introduced into the removal tower 600 at a vacuum negative pressure and discharging the ammonia gas to the outside; Guide the wastewater introduced into the removal tower 600 to the lower side to be collected in the discharge tank 800, and then discharged to the outside according to the ammonia concentration of the collected waste water, or the wastewater collected in the discharge tank 800 Ammonia removal method of the waste water comprising the step of returning back to the reservoir (200) side. The method according to claim 1, Measuring the hydrogen ion index of the waste water in the step of collecting the waste water in the storage tank 200 and supplying an alkaline solution to maintain the alkaline hydrogen ion index ammonia removal method of the waste water, characterized in that it further comprises. The method according to claim 2, And agitating the interior of the reservoir 200 after supplying the alkaline solution in the step of maintaining the hydrogen ion index of the waste water in an alkaline state. The method according to claim 1, Ammonia removal method of the waste water, characterized in that the waste water and the fine air by mixing with the air flowing from the outside in the step of miniaturization of the waste water and air into the mixture through the mixing tube 510 of the venturi tube type. The method according to claim 1, Ammonia removal method of the wastewater, characterized in that the minute inflow of the wastewater relative to the minute amount of the air flow in the step of miniaturizing by mixing the wastewater with the air flowing from the outside. The method according to any one of claims 1 to 5, The lower portion 630 of the removal tower 600 is configured in a straight line different from the cylindrical upper portion 610 to prevent backflow of the wastewater in the process of inhaling the ammonia gas by the vacuum negative pressure. To remove ammonia from wastewater.

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