KR20030061229A - Method for treating wastewater contained high concentration nitrogen - Google Patents

Abstract

PURPOSE: Provided is a method for treading wastewater containing high concentration nitrogen using opened and closed type electrolysis apparatus so as to generate only harmless nitrogen gas. CONSTITUTION: The method comprises the step of performing electrolysis of wastewater containing high concentration nitrogen while maintaining Cl concentration to 5,000 mg/L to remove nitrogen in the wastewater in accordance with chemical equations such as (i) 2NH4+2e→N2↑+4H2 by cathode reducing action, (ii) NH3+2HO- → 0.5N2↑ +3H2O+3e by direct anode oxidizing action, and (iii) 2NH3+6Cl-→N2↑+6HCl+6e- by indirect anode oxidizing action.

Description

Method for treating wastewater contained high concentration nitrogen

The present invention relates to a high concentration nitrogen-containing wastewater treatment method using an electrolysis method, in particular, the nitrogen form contained in domestic sewage or industrial wastewater can be treated irrespective of the composition and concentration of nitrogen components, and finally only nitrogen gas which is a harmless component It relates to a high concentration nitrogen-containing wastewater treatment method using the electrolysis method to be produced.

In general, when treating domestic sewage, industrial wastewater, and the like, a biological treatment method using microorganisms and an electrolysis method using electric energy are generally employed.

The electrolytic method may use electrolysis, electro-coagulation, or electro-flotation as a method for treating contaminants in household sewage or industrial wastewater with electricity and chemically.

Moreover, although the main purpose of conventional wastewater treatment is to proceed with treatment of COD and BOD components caused by organic pollutants contained in domestic sewage or industrial wastewater, in recent years, nitrogen (N), phosphorus It is well known that nutrients such as (P) cause rivers and lakes to be adversely affected, or red tide occurs frequently in the bay.

Conventionally, biological treatment has been used as a general method for treating nitrogen, which is to perform the primary treatment of physical and chemical treatment of domestic and industrial wastewater,

Secondary treatment with biological treatment is performed for the wastewater which has been subjected to the first treatment,

The purified wastewater was discharged by performing the tertiary treatment of the wastewater which was subjected to the secondary treatment, which is highly treated for the decomposition of hardly decomposable substances and the separation of nitrogen and phosphorus.

However, the size of the biological tank is increased, and the operating conditions are very demanding, and thus it is not used efficiently.

That is, the process of nitrogen treatment by the general biological treatment method is carried out by a two-step process involving two microorganisms, nitrosomonas (NITROSOMONAS) and nitrobato (NITROBATOR).

NITROSOMONAS

^{_{NH 4 + + 3 / 2O 2}} -----------------> NO 2 - + 2N + + H 2 O + CELLS.

NITROBACTOR

^{_{N0 2 + + 1 / 2O 2}} -----------------> NO 3 - + CELLS.

As in the above scheme, ammonia nitrogen was converted to nitrite in the first step, and nitrite was converted to nitrate in the second step.

That is, living sewage and industrial wastewater in the form of oxidizing nitrogen (TN) such as organic nitrogen, NH ₄ -N, NO ₂ -N, and NO ₃ -N will nitrify microorganisms.

And the process of denitrifying microorganisms,

^{_{6NO 3 - + 2CH 3 OH ----}} > 6NO 2 + 2CO 2 + 4H 2 O.

^{_{6NO 2 - + 3CH 3 OH ----}} > 3N 2 ↑ + 3CO 2 ↑ + 3H 2 O + 6OH -.

Although it is to be carried out by, but if the nitrogen form exceeds the limit of 2000mg / l, there is a problem that the economic efficiency is greatly reduced, the economical efficiency depends on the concentration of nitrogen form.

In addition, ammonia degassing method, breaking point chlorine injection method, ion exchange method, and the like are used as physical and chemical treatment methods, but they are not practically used due to the problems of secondary pollution and poor economic efficiency.

Accordingly, the present invention can treat nitrogen forms contained in domestic sewage or industrial wastewater irrespective of the composition and concentration of nitrogen components, and finally, a high concentration nitrogen-containing wastewater treatment method using electrolysis to generate only nitrogen gas, which is harmless. To provide that purpose.

The high concentration nitrogen-containing wastewater treatment method using the electrolysis method of the present invention for achieving the above object is applicable to both an open type electrolyzer or a closed type electrolyzer,

By the cathode reduction during the nitrogen removal process by electrolysis in the open or closed electrolyzer,

2NH ₄ + 2e -----> N ₂ ↑ + 4H _2.

And by direct anodization to oxidize and remove contaminants directly from the anode,

^{_{NH 3 + 3OH - -----> 0.5N}} 2 ↑ + 3H 2 O + 3e.

Also by indirect anodization to remove contaminants by intermediate organisms,

^{_{2NH 3 + 6CL - -----> N}} 2 ↑ + 6HCl + 6e -.

In other words. Nitrogen removal by electrolysis is to maintain more than 5,000mg / l Cl of sewage or industrial wastewater when the oxidation and reduction reaction are combined, so the reaction rate of indirect anodic oxidation is faster and it is caused by the complex reaction of oxidation and reduction. Allow complete denitrification.

1 is a schematic view showing a configuration according to an embodiment of the present invention.

2 is a schematic view showing a configuration according to another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: open electrolyzer 2: electrolytic injury

15: electrode unit 16: precipitation chamber

26: sediment discharge plate 30: closed electrolyzer

31: first electrode 32: second electrode

34: wastewater outlet 43: wastewater supply pipe

44: pressure pump 49: discharge pipe

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

1 is a view showing a configuration according to a first embodiment applied to an open electrolyzer which is a preferred embodiment of a high concentration nitrogen-containing wastewater treatment method using an electrolysis method according to the present invention.

The open electrolyzer 1 is formed such that the treated water recovery tank 4 extends to the right side while the floc discharge tank 3 extends to the left side at the top of the electrolytic flotation tank 2 which functions as the floating tank and the separation tank. and,

In the treated water recovery tank 4, a treated water storage part 6 having a water level adjusting valve is formed so that the treated water can be recovered through the recovered pipe 7.

In the treatment water inlet of the treatment water storage part 6, a barrier plate 8 is installed so that the bottom part is slightly immersed in the water surface and the floc flows into the treatment water storage part 6 by the barrier plate 8. To prevent you from coming in,

In the floc discharge device 5 disposed above the electrolytic flotation tank 2, rollers 9 and 10 are installed on the floc discharge tank 3 and the unlock plate 8 of the treated water recovery tank 4. In the meantime, a plurality of scrapers 11 combine belts mounted at predetermined intervals,

The rollers 9 and 10 move the scraper 11 while rotating by the drive motor 12 to scrape off the floc layer 13 floating on the water surface of the electrolytic injury tank 1 to discharge the floc. Discharge through the discharge pipe 14 connected to the bottom wall of (3),

The electrode unit 15 is installed below the electrolytic floatation tank 2 to supply water in a low voltage and high current state to electrolyze water to generate fine colloidal air and highly active hypochlorous acid composed of oxygen gas and hydrogen gas bubbles. So that

A lower inlet 17 is formed in the lower settling chamber 16 of the electrolytic flotation tank 2, and an upper inlet 18 is formed directly on the electrode unit 15 of the right side wall 2b to provide domestic sewage or industrial wastewater. It can be selectively introduced according to the type or physical property of

The electrolytic floatation tank 2 is installed to maintain the inclination along the left side wall 2c so as to maintain the inclination along the left side wall 2c. Towards to be formed to the passage passage 20 is formed to be converted into a narrow passage area,

The lower end of the drive drift plate 19 is supported by the shaft 21 so as to be able to swing so that the passage area of the ascending passage 20 can be varied,

The upper side of the right side wall 2b of the electrolytic flotation tank 2 is upwardly driven by the inclined portion 2d inclined outwardly, the front wall and the rear wall of the electrolytic flotation tank 2, and the aperture change plate 19. (20) and a separate guide passage 22 to be formed,

The guide passage 22 is connected to the lower portion of the upward passage 22 and the treated water recovery tank 4 from the upper side of the electrode unit 15,

In the guide passage 22, at least one or more (about three) inclined plates 23 are installed to be inclined in parallel with each other so as to be movable.

The bottom 16a of the precipitation chamber 16 is provided with an diffuser 24 for ejecting fine air to diffuse air supplied through the air supply pipe 25,

The front of the diffuser 24 is provided with a sediment discharge pipe 26 to form a plurality of inclined parallel to the electrode unit 15 and the diffuser 24 in the settling chamber 16 (about 5 pieces) The lower slant plate 27 guides the clean water to the electrode unit 15, and at the same time, it is possible to process impurities of colloidal air that cannot be treated by the inclined upper surface through the sediment discharge pipe 26.

Immediately above the electrode unit 15 of the electrolytic injury tank (2) to form a secondary chemical inlet (28) is configured to help the chemical reaction while injecting chlorine components in accordance with the characteristics of the waste water.

Therefore, if the waste water having impurities having a small specific gravity is introduced into the electrolytic flotation tank 2 through the upper inlet 18, and then a high voltage of low voltage is supplied to the electrode unit 15, fine colloidal air from the electrode unit 15 is applied. And impurities such as suspended substances and suspended solids contained in living sewage and industrial wastewater due to the ascending and diffusing power of the colloidal air during the ascension through the ascending passage 20 due to the generation of highly active hypochlorous acid. As well as the formation of nitrogen by the highly active hypochlorous acid is facilitated.

In addition, the floc which has colloidal air is adsorbed and has a floating force rises to the surface and is deposited on the surface so that the floc layer 13 is scraped off by the scraper 11 and discharged to the discharge pipe 14.

In addition, since the waste water having impurities having a high specific gravity is injected into the settling chamber 16 from the lower inlet 17, when the fine air is ejected through the diffuser 24, the impurities having a large specific gravity that cannot be treated by colloidal air are lower inclined plates ( 27) is guided and precipitated by the sediment discharge pipe 26, while impurities of specific gravity capable of treating colloidal air are moved upwards of the electrode unit 15 by fine air and then treated by colloidal air as described above. .

At this time, since the upward passage 20 becomes narrower upward, the colloidal air passing through the upward passage 20 gradually accelerates its ascending speed to obtain sufficient lifting force and diffusion force, which promotes cohesive bonding of impurities, thereby shortening floc raising and separation. It will be done in time.

Through the auxiliary chemical inlet 28 formed directly on the electrode unit 15 of the electrolytic injury tank (2) to help the chemical reaction while injecting the chlorine component in accordance with the characteristics of the waste water.

In addition, the secondary water is formed by the auxiliary electrode unit 29 provided on the left side of the barrier plate 8, through which the treated water is recovered through the recovery pipe 7, and the colloidal air is ejected to the upper and inner sides. Separating the gas introduced into the discharge pipe 14 to be discharged.

The treated water ascended through the upward passage 20 and the gas is completely removed is separated from the floc layer 13 by the barrier plate 8 in the treated water recovery tank 4 to separate the treated water reservoir 6. After that, it is recovered to the recovery pipe (7).

However, as described above, sufficient flotation force of the colloidal air is secured. As a result, flocs or impurities having a greater specific gravity than the treated water may be present in the floc layer 13 on the water surface. When descending in accordance with the inclined top surface of the inclined plate 23 is reintroduced in the upward passage 20 is absorbed by the floc layer 13 again by the action of the colloidal air to be discharged to the outside.

In addition, since the inclined plate 23 has a function of guiding the clean water to the upper side of the inclined plate, the clean water promotes separation of the floc layer 13 and the treated water.

During the treatment of the electrolysis, the nitrogen contained in the wastewater should be removed when treating general household sewage or industrial wastewater.

Therefore, when the power is supplied from the anode of the electrode unit 15 of the open type electrolyzer 1 to perform electrolysis,

By the action of cathode reduction at the cathode,

2NH ₄ + 2e -----> N ₂ ↑ + 4H _2,

And by the action of direct anodization at the anode,

^{_{NH 3 + 3OH - -----> 0.5N}} 2 ↑ + 3H 2 O + 3e,

By the action of indirect anodization at the anode,

^{_{2NH 3 + 6CL - -----> N}} 2 ↑ + 6HCl + 6e -,

This process is a complex process.

When chlorine is released by indirect oxidation at the anode, it reacts with ammonia nitrogen to produce nitrogen gas as the final product, as shown in the following equation.

_{^{2NH 4 + + 3HOCl - --->}} N 2 + 3H 2 O + 5H - + 3Cl -,

The reaction in this formula is chemically equilibrated at pH 7.6, such as the breakdown point reaction of chlorine, and is affected by the weight ratio and pH of chlorine and ammonia nitrogen, and at low pH, in addition to nitrogen, chloramine (NH ₂ Cl, NHCl ₂ , NCl ₃ ) is formed.

A reaction formula in which the ammonia nitrogen is removed by reacting with hypochlorous acid may be represented as follows.

NH ₄ ⁺ + HOCl ---> NH ₂ Cl + 5H ₂ O + H ⁺ ,

NH ₂ Cl + HOCl ---> NHCl ₂ + H ₂ O,

NHCl₂+ H₂O ---> NCl₃ + H₂O,

As can be seen in each of the reaction schemes, it can be seen that the oxidative reaction is carried out according to the pH and shows the same tendency as the break point reaction of chlorine.

The monochloramine (NH ₂ Cl) is converted into nitrogen while reacting as shown in the following formula when there are a lot of hypochloric acid in water.

2NH ₂ Cl + HOCl ---> N ₂ ↑ + 3HCl + H ₂ O,

Therefore, in the indirect reaction, there is a need for sufficient free chlorine to react with ammonia nitrogen to generate nitrogen gas as the final product.

Therefore, when the oxidation and reduction reactions are combined as above, the Cl concentration of domestic sewage or industrial wastewater is maintained at 5,000 mg / l or more. The denitrification by nitrogen removal is completed completely.

Figure 2 shows the configuration according to the second embodiment applied to the closed electrolyzer which is a preferred embodiment of the high concentration nitrogen-containing wastewater treatment method using the electrolysis method according to the present invention,

The closed electrolyzer 30 is composed of a substantially sealed structure by combining the first electrode 31 and the second electrode 32,

On the top of the first electrode 31 having a uniform uniform inner and outer diameters, a part of the electrode is attached and a cylindrical metal fitting 33 having a treated wastewater outlet 34 is attached thereto.

The upper end of the cylindrical metal fittings (33) is to be connected to the deformed cylindrical support metal fittings (35) attached to the metal blocking side (37) by a connecting piece (36),

The second electrode 32 having a smaller diameter than the first electrode 31 and having a substantially uniform inner and outer diameter is partially inserted into the first electrode 31 so that an upper portion thereof protrudes.

While forming the insulating material 38 made of synthetic resin between the second electrode 32 and the containment piece 37, the cap 40 is covered with a seal so as to prevent the separation by the 0 ring 39,

Titanium pipe 41 is connected to the upper end of the second electrode 32 so that the living sewage or industrial wastewater flows through the opened upper end,

One end of the wastewater supply pipe 43 is connected to the wastewater inlet by connecting a circular connecting member 42 to open the pressurized pump 44 on the other side to be connected to the wastewater tank 45,

The wastewater inlet 46 is opened at the lower end of the second electrode 32 so that the living sewage or industrial wastewater introduced through the inside of the second electrode 32 is the first electrode 31 and the second electrode 32. In between),

The lower end of the first electrode 31 is to be kept in a sealed state by the sealing lid 47 made of synthetic resin,

A spacer 48 made of synthetic resin is formed between the lower end portions of the first and second electrodes 31 and 32 so that the center axis of the first and second electrodes 31 and 32 coincide with each other. And at the same time arranged so that the predetermined spacing is kept even in the rectangular direction,

A second supply passageway 51 is provided upstream of the closed side 50 while attaching a closed side 50 to a discharge pipe 49 having an end connected to the treated wastewater outlet 34 of the first electrode 31. Through the filter (52) branched by the) to be discharged to the above-described finished drain tank 73,

The positive electrode 54 is connected to the first electrode 31, and the positive electrode 55 is connected to the second electrode 32 so that a current flows or an alternating current flows.

Therefore, when treating domestic sewage or industrial wastewater, the pressure pump 44 is operated while allowing a predetermined current to flow between the first and second electrodes 31 and 32. Then, the domestic sewage or industrial wastewater in the wastewater tank 45 is subjected to a predetermined pressure, for example, 6 kg / cm ² , and passes through the wastewater introduction pipe 43, the connecting bracket 42, and the titanium pipe 41. Is supplied to the second electrode 32.

Living sewage or industrial wastewater supplied to the second electrode 32 passes through the second electrode 32 and flows into the gap between the first and second electrodes 31 and 32 from the wastewater inlet 46. Pass between the first electrode 31 and the second electrode 32.

The electrical energy from the first and second electrodes 31 and 32 is given between the living sewage and industrial wastewater between the first and second electrodes 31 and 32, so that the polymers in the living sewage and industrial wastewater Inorganic or polymeric organic matter is treated with low molecular weight, and then the treated wastewater tank (53) is passed from the treated wastewater outlet (34) to the supply passage (49), the filter (52), and the second supply passage (51). To be stored.

Meanwhile, when the first electrode 31 and the second electrode 32 of the closed electrolyzer are supplied with power to perform electrolysis,

In the first electrode 31 of the cathode to which the wire is connected, by the cathode reduction action,

2NH ₄ + 2e -----> N ₂ ↑ + 4H ₂ ,

And in the second electrode 32 of the anode to which the + wire is connected by direct anodization,

^{_{NH 3 + 3OH - -----> 0.5N}} 2 ↑ + 3H 2 O + 3e,

In addition, in the second electrode 32, due to the action of indirect anodization,

^{_{2NH 3 + 6CL - -----> N}} 2 ↑ + 6HCl + 6e -,

This process is a complex process.

When chlorine is released by the indirect oxidation reaction, it reacts with ammonia nitrogen to generate nitrogen gas as a final product.It is affected by the weight ratio and pH of chlorine and ammonia nitrogen, and when pH is low, in addition to nitrogen, chloramine (NH ₂ Cl, NHCl ₂ , NCl ₃ ) are formed.

When the monochloramine is a lot of hypochlorous acid in water, it is often converted into nitrogen. Therefore, it is necessary to make sufficient chlorine free so that chlorine reacts with ammonia nitrogen to generate nitrogen gas as the final product. do.

Therefore, when the oxidation and reduction reactions are combined as described above, the Cl concentration of domestic sewage or industrial wastewater is maintained at 5,000 mg / l or more, so that the reaction rate of indirect anodic oxidation is increased, and thus the electrolysis is performed by the complex reaction of oxidation and reduction. The denitrification by nitrogen removal is completed completely.

In the high concentration nitrogen-containing wastewater treatment method using the electrolysis method of the present invention configured as described above, a process of 2NH ₄ + 2e ---> N ₂ ↑ + 4H ₂ by cathodic reduction in an electrolyzer is performed, or directly by ^{_{NH 3 + 3OH - ---> 0.5N}} 2 ↑ + 3H 2 O + 3e process is performed, or by indirect anodizing ^{_{2NH 3 + 6CL - ---> N}} 2 ↑ + 6HCl + 6e - process When this is carried out, the Cl concentration of the domestic sewage or industrial wastewater is maintained at 5,000 mg / l or more, so that the reaction rate of indirect anodic oxidation is accelerated, so that complete denitrification can be achieved by a complex reaction of oxidation and reduction.

Claims (1)

In the high concentration nitrogen containing wastewater treatment method using the electrolysis method, By the action of cathodic reduction, 2NH ₄ + 2e -----> N ₂ ↑ + 4H ₂ , And by the action of direct anodization, ^{_{NH 3 + 3OH - -----> 0.5N}} 2 ↑ + 3H 2 O + 3e, By the action of indirect anodization, ^{_{2NH 3 + 6CL - -----> N}} 2 ↑ + 6HCl + 6e -, The high concentration nitrogen-containing wastewater treatment method using the electrolysis method to speed up the reaction rate of indirect anodic oxidation by maintaining the Cl concentration of the domestic sewage or industrial wastewater more than 5,000mg / l because the process is made complex.