KR100315874B1 - Method and Apparatus of Biological Nitrogen Removal from the High Concentration Industrial Wastewater - Google Patents

Abstract

The present invention induces nitrite oxidation only up to nitrite nitrogen using FA (free ammonia), and then directly denitrifies it to reduce the amount of oxygen required for nitrification as well as to reduce the consumption of external carbon sources required for denitrification. The present invention relates to a method for removing biological nitrogen from a high concentration wastewater and a device thereof. The method and apparatus for removing biological nitrogen from a high concentration wastewater include a storage tank (10) for storing an influent to adjust an inflow load and appropriately supplementing alkalinity. Nitrobacter activity is inhibited by FA (free ammonia; NH ₃ ) of the raw water constantly introduced by the storage tank 10 to control nitrification to nitrite nitrogen, and the first aerobic A first anoxic denitrification tank 30 which denitrates the inflow water nitrified with nitrite nitrogen in the oxidation tank 20 by its own carbon source, In the first anoxic denitrification tank (30), a second aerobic agent for oxidizing not only ammonia contained in raw water in which organic matter decomposition has occurred using its own carbon source but also ammonia not removed in the first aerobic oxidizing tank (20) with nitrite nitrogen An oxidizing tank 40, a second anoxic denitrification tank 50 for denitrifying the nitrite nitrogen oxidized in the second aerobic oxidizing tank 40 by an external carbon source selectively administered, and the second anoxic denitrification tank ( 50) is composed of a settling tank 60 to selectively remove the denitrified raw nitrogen in the chemical treatment of the raw water denitrified in 50) to reduce the external carbon source oxygen requirements and residence time as well as to improve the denitrification efficiency Will be effective.

Description

Method and Apparatus for Removing Biological Nitrogen from Highly Concentrated Wastewater {Method and Apparatus of Biological Nitrogen Removal from the High Concentration Industrial Wastewater}

The present invention relates to a method for removing biological nitrogen from a high concentration wastewater and a device thereof, and in particular, wastewater introduced without oxidizing to nitrate nitrogen (NO ₃ ^-- N) using microorganisms is nitrite nitrogen (NO ₂ ^-- N). The present invention relates to a method and apparatus for biological nitrogen removal of high concentration wastewater which is directly denitrified after induction by oxidation.

Recently, in Korea, environmental pollution is rapidly progressed due to population increase, urban concentration, and industrial development, and the damage of water environment is intensified. Moreover, nutrients such as nitrogen and phosphorus are introduced into water resources such as rivers and lakes, causing eutrophication. By doing so, there was a problem of destroying the aquatic ecosystem due to the death of fish and shellfish, declining the utilization value of water resources, and raising the cost of water treatment.

In addition, when the nitrogen is released into the environment mainly composed of organic nitrogen and ammonia nitrogen in the waste water, the organic nitrogen and ammonia nitrogen is converted to nitrite in nature, and then become nitrate, which requires a large oxygen demand. There was this.

Accordingly, developed countries have already developed various nitrogen and phosphorus removal systems in order to remove nitrogen and phosphorus, which are the causes of eutrophication, in the sewage treatment process, and are accumulating the applied technologies. However, Korea has operated only the activated sludge process, which is the second treatment, focusing on the removal of organic matters, with the purpose of water treatment, so that the nitrogen and phosphorus in question are left untreated and flowed into rivers or lakes and reservoirs. It is true.

Therefore, in order to solve this problem, a process for simultaneously treating nitrogen and phosphorus by a physical, chemical or biological unit process has been developed. However, in the biological treatment process capable of removing nitrogen through appropriate analysis and environmental control, Let's just look at it. These biological nutrient treatment processes are independent of each other as follows, and how to apply them appropriately in the treatment process is a problem.

First, looking at the characteristics of municipal sewage, phosphorus concentration is about 5 to 15 mg / L, of which synthetic detergent is composed of 50 to 70%, manure and food residue 30 to 50%, more specifically the reaction of such phosphorus Explained as follows.

The removal of phosphorus biologically uses the release and intake of phosphorus in the anaerobic and aerobic processes, and the suspended solids are removed from the initial settling tank and the bio-P microorganisms such as Acinetobactor, Pseudomonas, Aeromomas, etc. As a result, low molecular weight substances are accumulated in cells in the form of poly (β-hydroxybutyric acid) (PH-) and orthophosphates are released to the outside of the cells. Bio-P microorganisms that have released phosphorus are ingested excessively while oxidizing and decomposing organic matter and accumulated PHB in an aerobic state, and the phosphorus removal process is completed by appropriately removing the microorganisms ingesting excess phosphorus. do. In this case, in order to ingest excess phosphorus, phosphorus release should be carried out first. When phosphorus is released, if an electron acceptor other than oxygen, that is, a material such as NO ₃ ⁻ is present, phosphorus emission is prevented. Will inhibit efficient phosphorus release.

At this time, the extracellular organic matter is moved into the cell with energy, which is called active transport, and the absorbed organic matter is stored as PHB, and when it is in aerobic state, it decomposes the PHB stored in the cell and ATP (adenosine 5). '-triphosphate: adenosine 5'-triphosphate) is synthesized and this energy is absorbed and stored as polyphosphoric acid in cells. At this time, luxury uptake of phosphorus is performed to synthesize inorganic phosphoric acid by ingesting excess phosphoric acid from the solution. Therefore, the biological removal of phosphorus is finally made by discharging the microorganisms ingested excessively in the form of sludge in the aerobic state, it is removed by the absorption of phosphorus due to environmental changes of the same microorganisms, it is necessary to return the appropriate sludge.

Next, let's look at the reaction of nitrogen.

In general, nitrogen in the inflow of sewage water is organic nitrogen (N-N) and ammonia nitrogen (NH ₄ ⁺ -N), which is nitrate nitrogen (NO ₃ -N) through nitrification in an aerobic activated sludge aeration tank. ), The reactor of the next step is maintained in anoxic state (Anoxic) to reduce the nitrate nitrogen (NO ₃ -N) to nitrogen gas. That is, the process of removing such nitrogen components from the wastewater includes a nitrification process for converting ammonia and organic nitrogen in the influent into nitrate from aerobic conditions, and biological reduction of nitrified nitrate under anoxic conditions. It is composed of a denitrification process to convert to nitrogen gas by the.

The nitrification process uses an open pure oxygen activated sludge treatment process treated by microorganisms in an aerobic state to decompose organic materials and to nitrate nitrogen. In this case, the nitrate introduced by nitrification in the nitrification process contains a large amount of nitrogenous organic matter and ammonia, which is not decomposable but also does not have a high load of organic matter. Phosphorylation takes place and requires an anoxic denitrification process to remove it. At this time, the denitrification process is induced by a hydrogen donor (hydrogen doner) to convert the nitrate obtained in the nitrification process to nitrogen gas by biological reduction, which will be described in more detail as follows.

In the nitrification process, ammonia nitrogen (NH ₄ ⁺ -N) is converted into nitrite nitrogen (NO ₂ ^-- N), and in the form of nitrate nitrogen (NO ₃ -N) by biological oxidation. Microorganisms involved in this metabolic process appear anywhere in the oxygen-rich aerobic state where organic matter is converted and ammonium is released.

In the first stage of nitrification, ammonia nitrogen is oxidized to nitrite nitrogen, and the energy obtained by the microbial oxidation of ammonium makes carbon dioxide fix on microorganisms and is used for metabolism. On the other hand, the oxidation of the nitrite nitrogen to nitrate nitrogen is also made in the same manner.

As such, the two stages of metabolism are caused by different kinds of bacteria, the oxidation of ammonia nitrogen is carried out by microorganisms belonging to the family Nitrosomonas, and the oxidation of nitrite nitrogen is carried out by microorganisms belonging to the family Nitrobacter (Bitton, 1994)

Nitrosomonas

^{_{NH 4 + + 1.5O 2 → NO}} 2 - + H 2 O + 2H + (1)

Nitrobacter

^{_{NO 2 - + 0.5O 2 → NO}} 3 - (2)

Therefore, the overall reaction is represented by the following equation.

NH ₄ ⁺ + 2O ₂ → NO ₃ + 2H ⁺ + H ₂ O (3)

Carbon dioxide is used as the carbon source for both microbial groups, and their energy is obtained from the oxidation of inorganic nitrogen compounds (chemolithoautotrophy), while other microorganisms in activated sludges derive energy from the oxidation of organic carbon compounds, and these components are also used as carbon sources. Use (heterotrophy).

In addition, the denitrification process is a process of reducing and removing nitrates (NO ₃ ⁻ ) and nitrites (NO ₂ ⁻ ) instead of oxygen by nitrogen gas in the absence of oxygen (Anoxic). (NO ₃ ^-), and nitrite (NO ₂ ^-) acts as an electron acceptor (electron acceptor) to indicate the physicochemical nitrate (or nitrite), the reduction reaction is reduced to nitrogen gas, proceeding according to the same order as the equation (4) below do.

e ^- e ^- e ^- e ^-

_{^{NO 3 - → NO 2 - →}} NO → N 2 O → N 2 (4)

As described above, in order to reduce the nitrate nitrogen to nitrogen gas through the denitrification process, an electron donor is required, and as the electron donor used, various organic materials (for example, Acetic acid, citric acid, acetone, methyl alcohol, and glucose). In addition to the greatest reduction in cell synthesis, economical methyl alcohol is widely used (Barnes et al., 1983).

The denitrification reaction takes place in two stages of reaction as follows.

^{_{NO 3 - + 0.33CH 3 OH →}} NO 2 - + 0.67H 2 O (5)

^{_{0.5CH 3 OH + NO 2 - →}} 0.5CO 2 + 0.5H 2 O + 0.5N 2 + OH - (6)

Therefore, the entire reaction formula is as shown in equation (7).

^{_{NO 3 - + 0.833CH 3 OH →}} 0.5N 2 + 1.167H 2 O + 0.833CO 2 + OH - (7)

Ignoring cell synthesis in the denitrification reaction, the amount of methyl alcohol required to reduce 1 mg of nitrate and nitrite nitrogen was 1.90 mg and 1.14 mg, respectively, and increased to 2.47 mg and 1.53 mg when considering cell synthesis. Done. Thus, the amount of methyl alcohol required to denitrate nitrate and nitrite nitrogen is shown in Eq. (8) (U.S. EPA, 1993).

C_m= 2.47 NO₃ ^--N + 1.53NO₂ ^--N + 0.87DO (8)

C _m : required methanol concentration (mg / L)

DO: dissolved oxygen removed (mg / L)

As described above, biological treatment processes (hereinafter, referred to as advanced treatment processes) that simultaneously treat nitrogen and phosphorus removal by appropriately mixing them include A ₂ / O processes, Bandenpho processes, and the University of Cape Town. ) Process, VIP (Virginia Initiative Plant) process, etc. If this is described in more detail as follows.

The A ₂ / O method, as shown in Figure 1A, the sedimentation treatment in the primary sedimentation tank 100, the inflow of sewage and waste water from which the suspended solids are removed anaerobic reaction tank 200, anoxic reaction tank (300) ), And by discharge through the aerobic reactor 400, the secondary precipitation tank 500, the residence time of the oxygen-free reaction tank 300 takes about 1 hour. In the anoxic reactor 300, there is no dissolved oxygen, but chemically bonded oxygen in the form of nitrate and nitrite is introduced from the aerobic reactor into the nitrified MLSS (Mixed Liquor Suspended Solids: suspension solids mixed solution) to denitrify nitrogen nitrate. Phosphorus discharged from the anaerobic reactor 200 is excessively absorbed by the aerobic reactor 200 in the rear stage and removed through sludge disposal, and the inflow water from the secondary precipitation tank 500 in the anaerobic reactor 200. 0.5 times of return sludge is returned and flowed in.

In addition, the modified Badenpho method, as shown in FIG. 1B, is a modification of the A ₂ / O method to increase the removal efficiency of phosphorus and nitrogen, wastewater through the first settling tank 100 Anaerobic reactor 200, the first anoxic reactor 300, the first aerobic oxidation tank 400, the second anoxic reactor 500, the second aerobic reactor 600 and the second precipitation tank 700, etc. Through a series of processing through the discharge. At this time, the first aerobic oxidation tank 400 conveys four times the amount of inflow water, and the second settling tank 700 conveys the return sludge of 0.5 times the inflow water to the anaerobic reactor 200.

In addition, the UCT (University of Cape Town) method, as shown in Figure 1C, the sludge conveyed inlet water, such as wastewater through the first settling tank 100 anaerobic reactor 200, anoxic reactor 300, aerobic Processed and discharged in series through the reactor 400, the second settling tank 500, in this case, in order to reduce the interference caused by NOx of the return sludge, the anaerobic reaction tank 300 is anaerobic 1 to 2 times the amount of inlet water. In the aerobic reaction tank 400, the aerobic reaction tank 400 is returned to the oxygen-free reaction tank 300, and in the second precipitation tank 500, the return sludge is 0.5 times the inflow water. 200).

In addition, the VIP (Virginia Initiative Plant) method, as shown in Figure 1D, anaerobic reactor 200, anoxic reactor 300, aerobic reactor 400, the inflow of sewage, such as wastewater through the first settling tank 100 , And discharged after treatment through the second settling tank 500, in which the oxygen-free reaction tank 300 is returned to the anaerobic reactor 200, 1-2 times the amount of inflow water, the aerobic reactor 400 and the first In the two-precipitation tank 500, the conveying sludge 1 times the amount of inflow water is returned to the oxygen-free reaction tank 300.

However, when comparing the above formula (1) and formula (3) in the nitrification reaction as described above, when ammonia nitrogen is oxidized to nitrite nitrogen, oxygen consumption is 25% less than that of nitrate nitrogen. It can be seen. Therefore, the method of oxidizing with nitrate nitrogen (NO ₃ ^-- N) rather than nitrous nitrogen as in the conventional nitrogen removal process, and then denitrified by nitrogen gas to remove the problem that the oxygen requirements are relatively increased do.

In addition, as shown in Equation (8) of the denitrification reaction, when the nitrogen is removed by denitrification in the existing nitrate nitrogen state, the methyl alcohol requirement is 2.47, which is about 40% of that of 1.53 when denitrification is carried out directly in the nitrite nitrogen state. There is a problem that the requirements of the carbon source is relatively increased.

Therefore, this nitrate to solve the conventional problems (NO ₃ ^- -N) the incoming waste water without oxidation to nitrite ^- after inducing the oxidation of (NO ₂ -N), it immediately denitration The SHARON process was developed, which will be described in more detail as follows.

In the Sharon method, Nitrobacter grows faster than Nitrosomonas during wastewater treatment at room temperature (5 to 20 ° C), and nitrification is carried out so that ammonia nitrogen (NH ₄ ⁺ -N) is converted into nitrate nitrogen (NO ₃ ^-- N). At high temperatures (35 ° C), Nitrosomonas grows faster than Nitrobacter, leading to a wash-out of Nitrobacter and allowing only Nitrosomonas to be present in the reactor, thereby nitrousizing ammonia nitrogen (NH ₄ ⁺ -N). The principle is to oxidize only to nitrogen (NO ₂ ^-- N). In this case, in the case of the Sharon method, the loading of ammonia nitrogen (NH ₄ ⁺ -N) is 1kg / m ³ in a 35 ℃ single reaction tank, the cyclic aeration type (90%) of the nitrification rate of about 90% Indicated.

However, the conventional Sharon method as described above should be provided with a separate heating device to maintain a high temperature of more than 35 ℃ to use the oxidation of nitrous nitrogen (NO ₂ ^-- N), and to drive and maintain it There was a problem that causes an increase in management costs.

In addition, the conventional Sharon method is used for denitrification as well as about 70% of the methyl alcohol injected by taking a batch operation method of repeating the nitrification-denitrification reaction through a cyclic aeration in the same reaction tank during operation. Even if the supply is blocked, there is a problem that denitrification efficiency decreases because a certain time passes without going directly to anoxic state.

In addition, the conventional Sharon method has a problem in that only the pure nitrogen oxide microorganism in the reactor by operating a high concentration of nitrogen containing wastewater having a very low solids concentration by centrifugation in advance in the sludge treatment process.

An object of the present invention is to solve the conventional problems as described above, in particular, it is possible to reduce the amount of oxygen required for nitrification by directly denitrifying and inducing nitrite only up to nitrite nitrogen using FA (free ammonia). In addition, the present invention provides a method and apparatus for removing biological nitrogen of high concentration wastewater, which can reduce consumption of external carbon sources required for denitrification.

In addition, another object of the present invention is to induce denitrification by nitrification of nitrous nitrogen (NO ₂ ^-- N) to remove the biological nitrogen of the high concentration wastewater to reduce the residence time required by improving the reaction rate during denitrification A method and apparatus are provided.

In addition, another object of the present invention is not equipped with a return line compared to the conventional nitrogen removal process can not only simplify the treatment system, thereby reducing the biological nitrogen of the high concentration wastewater to reduce the maintenance costs required for operation A method and apparatus are provided.

In order to achieve the above object, the biological nitrogen removal method of the high concentration wastewater of the present invention and the device are the biological nitrogen removal method of the high concentration wastewater of the present invention by using FA (free ammonia) to selectively inhibit the activity of Nitrobacter nitrate nitrogen It can be operated at room temperature by inhibiting nitrification to (NO ₃ ^-- N) and causing accumulation of nitrite nitrogen (NO ₂ -N).

In addition, the biological nitrogen removal apparatus of the high concentration wastewater of the present invention oxidizes nitrogen to nitrite nitrogen (NO ₂ -N) through a first aerobic oxidizing tank and then first denitrifies using a carbon source of raw water in a first anoxic denitrification tank. The excess nitrogen is oxidized to nitrite nitrogen (NO ₂ -N) in a series of aerobic oxidation tanks, and then denitrified using an external carbon source in a second anoxic denitrification tank.

1 is a schematic diagram illustrating a general biological denitrification and dephosphorization process.

1A shows an A ₂ / O process,

Figure 1B shows a Badenpo process,

1C shows the UCT process,

1D shows the VIP process.

Figure 2 is a schematic diagram showing a biological nitrogen removal process of the present invention.

Figure 3 is a graph showing the inhibition (inhibition) to nitrification of the present invention,

Figure 3A shows the measurement results at 20 ℃,

3A shows the measurement results at 35 ° C.

Figure 4 is a graph showing the nitrogen behavior according to the SRT of the first aerobic oxidation tank of the present invention.

Figure 5 is a graph showing the nitrification rate according to the NH ₄ -N loading (loading) of the present invention.

Figure 6 is a graph showing the nitrite oxidation rate according to the inflow SCOD / NH4 + -N ratio.

Figure 7 is a graph showing the nitrite oxidation rate according to the SRT change at 20 ℃ and 35 ℃.

<Explanation of symbols for the main parts of the drawings>

10: storage tank 20: first aerobic oxidation tank

30: first anoxic denitrification tank 40: second aerobic oxidation tank

50: second anoxic denitrification tank 60: sedimentation tank

Hereinafter, the present invention configured as described above will be described in detail with reference to the drawings according to the technical idea of the biological nitrogen removal method and apparatus of the high concentration wastewater. Figure 2 is a schematic diagram showing a biological nitrogen removal process of the present invention, Figure 3 is a graph showing the suppression of the nitrification of the present invention, Figure 4 shows the nitrogen behavior according to the SRT of the first aerobic oxidation tank of the present invention Figure 5 is a graph showing the nitrification rate according to the NH ₄ -N loading (loading) of the present invention, Figure 6 is a graph showing the nitrite oxidation rate according to the inflow SCOD / NH4 + -N ratio, Figure 7 The graph shows the nitrite oxidation rate according to the SRT change at 20 ℃ and 35 ℃.

The present invention provides a Nitrobacter by storage tank 10 for adjusting the inflow load by adjusting the inflow load and appropriately replenishing alkalinity, and FA (free ammonia; NH ₃ ) of raw water uniformly introduced by the storage tank 10. Of the first aerobic oxidizer 20 to control nitrification to nitrite nitrogen and the first anoxic nitrate to denitrify the influent nitrified with nitrite nitrate in the first aerobic oxidizer 20 by its own carbon source. Nitrous acid not only removed in the first aerobic oxidizing tank 20 but also in ammonia contained in raw water in which organic matter decomposition occurred in the denitrification tank 30 and the first anoxic denitrification tank 30 using its own carbon source. A second anaerobic denitrification which denitrates by a second aerobic oxidizing tank 40 which is oxidized with nitrogen and an external carbon source which is selectively administered by oxidizing nitrous oxide which is oxidized in the second aerobic oxidizing tank 40 It consists of a tank (50), and a precipitation tank (60) for selectively removing chemically treated raw water denitrated in the second anoxic denitrification tank (50) to precipitate out and remove some unremoved particulate nitrogen. Explained as follows.

NaOH or NaHCO ₃ is administered to the storage tank 10 to maintain an alkalinity / NO ₄ ^-- N ratio of 7.14.

Media is selectively administered to the second aerobic oxidizer 40 to maintain stable nitrification.

Alkalinity is optionally supplemented to the second aerobic oxidizer 40.

In addition, the denitrification tank 30 is distributed from the storage tank 10 to the first anoxic denitrification tank 30 so that denitrification can be performed using its own carbon source of influent.

In addition, the inflow amount distributed from the storage tank 10 to the first anoxic denitrification tank 30 is introduced at 25 to 75% of the inflow flow rate depending on the inflow organic matter / nitrogen ratio and the loading of ammonia nitrogen.

In addition, the precipitation tank 60 is selectively administered with aluminum sulfate (Alum), ferric chloride (Ferric Chloride) to remove the phosphorus.

In addition, the present invention adjusts the SRT (or HRT) according to each temperature to prevent Nitrobacter from acclimation to FA, so that nitrogen is nitrite in aerobic state to be denitrified by nitrification of nitrous nitrogen (NO ₂ -N). After oxidizing with nitrogen (NO ₂ -N), the primary denitrification is carried out using an influent carbon source in anoxic state, and the excess nitrogen is oxidized with nitrite nitrogen (NO ₂ -N) in aerobic state, and then oxygen free. Denitrification by selectively using an external carbon source in the state, which will be described in more detail as follows.

The present invention does not require a transport facility by operating hydraulic retention time (HRT) and sludge retention time (SRT) in the same manner.

In the present invention, the sludge residence time (SRT) is 12 hours to 10 days.

Next will be described in more detail with reference to the embodiment of the present invention configured as described above. These examples are intended to illustrate the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited to these examples.

2 is a schematic diagram of a method for removing biological nitrogen of a high concentration wastewater according to the present invention and a device for implementing the device, wherein 10 is a storage tank, 20 is a first aerobic oxidation tank, 30 is a first anoxic denitrification tank, and The second aerobic reactor, 50 is the second anoxic denitrification tank and 60 is the precipitation tank.

The storage tank 10 has a lower concentration of Alkalinity / NH ₄ ⁺ -N of raw water than 7.14, which is required for nitrous oxidation, due to the high concentration of NH ₄ ⁺ -N in waste nitrogen-containing waste liquors. ) Is a limiting factor, and nitrite oxidation gradually decreases when the Alkalinity / NH ₄ ⁺ -N ratio is lower than 7.14. Therefore, NaOH or NaHCO ₃ is injected from the storage tank 10 to replenish the alkalinity so that the Alkalinity / NH ₄ ⁺ -N ratio is 7.14.

In addition, in the first aerobic oxidizing tank 20, Nitrobacter utilizes inhibition by FA (free ammonia (NH ₃ )) in nitrifying microorganisms to induce accumulation of nitrite nitrogen (NO ₂ ^-- N). by suppressing the nitrification to the ^- (NO ₃ -N) nitrite nitrogen, nitrate nitrogen in ^- (NO ₂ -N) nitrite nitrogen ^- is the accumulation of the (NO ₂ -N) occurs. At this time, by appropriately adjusting the sludge residence time (SRT) according to the temperature, it is possible to prevent Nitrobacter from acclimation to FA, thereby enabling stable nitrite oxidation. For this purpose, the hydraulic retention time (HRT) was operated almost equal to the sludge retention time (SRT) by not having a separate sludge residence time.

As described above, the effects of the temperature in the first aerobic oxidation tank 20 in which organic matter decomposition and NO ₂ -N nitrification of ammonia occur are as follows.

First, the ammonium uptake rate (AUR) value when the temperature of the first aerobic oxidizing tank 20 is 35 ° C. in pig waste water is 14.5 mg NH ₄ ⁺ hour as a result of using digested effluent water in which organic matter is almost decomposed. were -N / L, the organic material containing a piggery was the result per 13.1㎎NH ₄ ⁺ -N / L with the raw water, in the experiments with wastewater treatment plant wake water digestion supernatant was 9.3-16.3㎎NH ₄ ⁺ -N / L per hour . On the other hand, the first ammonia removal rate (AUR) values when the temperature is 20 ℃ aerobic oxidation tank 20 were respectively 12㎎NH ₄ ⁺ -N / L and 7.1㎎NH ₄ ⁺ -N / L per hour, When digestive supernatant of sewage treatment plant was used, it was 3.6-4.0mgNH ₄ ⁺ -N / L per hour.

In addition, the specific nitrification rate (SNR) when the temperature of the first aerobic oxidizing tank 20 is 35 ° C. in pig waste water was 15.8 mg NH 4 -N / gMv per hour as a result of using digestive effluent, The results of the experiment were 9.4mgNH4-N / gMv per hour, and the experimental results using digestive supernatant in the sewage treatment plant was 1.9-20.3mgNH4-N / gMv per hour. On the other hand, the specific nitrification rate (SNR) when the temperature of the first aerobic oxidizing tank 20 is 20 ° C. was 14.4 mgNH4-N / gMv and 5.9 mgNH4-N / gMv per hour, respectively. The experimental result was 0.6 mg NH 4 -N / gMv per hour. At this time, the alkalinity consumption of the first aerobic oxidizer 20 was similar to both 35 ℃ and 20 ℃, an average of 6.6 mg Alkalinity / mg NH ₄ ⁺ -N was lower than the theoretical value of 7.14.

The first anoxic denitrification tank 30 denitrates nitrogen nitrated with nitrite nitrogen (NO ₂ -N) in the first aerobic oxidation tank 20 using its own carbon source distributed and introduced from the storage tank 10. . At this time, as a result of the experiment using the pig waste water, the specific denitrification rate (SDNR) was very high as 19.8 mgNO ₂ ^-- N / gMv at 35 ℃ per hour, 14.9 mgNO ₂ ^-- N / gMv at 20 ℃ . Further, the sewage treatment plant wake each experimental results using the digestion supernatant water per hour 3.35㎎NO ₂ ^- found to -N / gMv ^- -N / gMv and 2.37㎎NO _2.

The second aerobic oxidizing tank 40 uses ammonia nitrogen (NO) not only removed in the first aerobic oxidizing tank 20 but also ammonia contained in raw water from which organic matter decomposition occurs using its own carbon source in the anoxic denitrification tank. ₂ -N). Optionally, media can be optionally added to achieve stable nitrification. In general, media can help the growth of microorganisms with slow growth rate, and various microbial species form clusters, which have the advantage of excellent ability to cope with temperature, pH fluctuations, impact loads, and incompatibilities. In this case, the use of such media is selectively determined according to the raw water to be processed and the operating conditions.

In addition, in the second aerobic oxidation tank 40, as shown in FIG. 6, the SCOD / NH ₄ ⁺ -N ratio is adjusted lower than that of the first aerobic oxidation tank 20, so that an improvement effect for the nitrous oxidation reaction is advantageous. Will be.

The second anoxic denitrification tank 50 denitrates the nitrite nitrogen (NO ₂ -N) oxidized in the second aerobic oxidation tank 40 using an external carbon source. In order to calculate the required amount of carbon source during operation of the second anoxic denitrification tank 50, the amount of methyl alcohol injected was determined according to Equation (8).

For -N removal ratio was ^{_{35 ℃ 1.45~2.38 ㎎SCOD / ㎎NO 2 -}} - wherein the second operation during the anaerobic denitrification tank (50) SCOD consumption / NO ₂ -N (1.24~1.59㎎ methyl alcohol / ₂ ㎎NO ^- -N), 20 ℃ the 1.74~2.35㎎SCOD / ㎎NO ₂ ^- -N (1.16~1.57㎎ methyl alcohol / ㎎NO ₂ ^- as -N), which common NO ₃ ^- -N SCOD during denitrification consumption / 50% of the NO ₃ ^-- N removal ratio of 3.75 to 4.50 mg SCOD / mg NO ₂ ^-- N (1.16 to 1.57 mg methyl alcohol / mg NO ₂ ^-- N) was significantly reduced in the consumption of carbon sources. Denitrification has been shown to be very economical. In the denitrification, alkalinity recovery was 3.16 mgAlkalinity / mg NO ₂ ^-- N at 35 ° C, and 2.91mgAlkalinity / mgNO ₂ ^-- N at 20 ° C.

The sedimentation tank 60 is selectively treated with aluminum sulfate (Alum), ferric chloride (Ferric Chloride), etc. to separate and treat raw water with sediment sludge and treated water.

In the present invention, as a result of the study on the factors that induce nitrite oxidation, the biggest factor inducing nitrite oxidation to nitrite is Nitrobacter (NH ₃ ) due to the inhibition of nitrobacter (NH ₃ ) to free ammonia (NH ₃ ) This is because nitrification to ₃ ^-- N is suppressed and nitrous nitrogen (NO ₂ ^-- N) is accumulated. Therefore, by appropriately adjusting the SRT (or HRT) according to the temperature and inflow characteristics, Nitrobacter can be prevented from complying with FA, thereby inducing stable nitrous oxidation. Therefore, in the case of the present method it is possible to apply not only 35 ℃ but also at room temperature of 20 ℃.

In the present invention, the nitrous oxidation efficiency is improved by adjusting the SCOD / NH ₄ ⁺ -N ratio. That is, the second aerobic oxidizer 40 is configured to take influent with a lower SCOD / NH ₄ ⁺ -N ratio compared to the first aerobic oxidizer 20.

As above, look at the inhibition by FA that causes nitrite is as follows.

Figure 3 shows the experimental values of the laboratory in the graph proposed by Athonisen in 1976 to explain the inhibition on nitrification. As shown in the experimental results of the present invention, as shown in Figure 3, most appear in the region 2, FA causes the inhibition of Nitrobacter activity to accumulate nitrite nitrogen (NO ₂ ^-- N). In other words, the FA is an important factor for inducing nitrification by causing inhibition in Nitrobacter. At this time, region 1 shows inhibition against Nitrobacter and Nitrosomonas, region 2 shows inhibition to Nitrobacter, region 3 shows complete nitrification, and region 4 shows inhibition to Nitrobacter by FNA.

First, as a result of testing the digester digestion supernatant at 35 ℃, the effect on SRT in the inhibition of nitrous oxidation by FA is as follows. If the SRT is longer, as shown in FIG. 4, complete nitrification, rather than nitrous oxidation, occurs, in particular, optimal nitridation was observed in 2 to 4 days, and was completely in excess of 6 to 8 days. Nitrification proceeded. In this case, as shown in FIG. 7, the SRT that is completely nitrified instead of nitrous oxide is changed depending on the temperature of the study, so that the SRT according to the temperature as well as the inhibition by FA in the present process using the biological nitrous oxide reaction. Control is an important process factor. On the other hand, Figure 5 shows the nitrification rate according to NH ₄ ⁺ -N loading (loading) when operating in HRT 4 days using pig waste water at 20 ℃.

Next, the effects of SCOD / NH ₄ ⁺ -N ratio on the inhibition of nitrite oxidation by FA are as follows. As shown in FIG. 6, the SCOD / NH ₄ ⁺ -N ratio shows a tendency that the nitrite oxidation rate decreases as it is increased, in particular, when the nitrite oxidation rate is 2 or less, about 30% more than that of 5 or more. Able to know. This is caused by the fraction of nitrifying microorganisms in the total MLSS decreased relatively as the SCOD / NH ₄ ⁺ -N ratio increases. The nitrite oxidation rate by the SCOD / NH ₄ ⁺ -N ratio is selectively applied according to the denitrification efficiency and influent of the nitrogen removal system of the present invention.

The present invention targets high concentration nitrogen-containing wastewater, such as livestock wastewater, leachate, sewage treatment plant return water, etc. The following is a design example based on experimental results using livestock wastewater.

The abbreviation used in the present invention is as follows.

HRT: Hydraulic Retention time

BOD: Biological Oxygen Demand Biochemical Oxygen Demand

COD: Chemical Oxygen Demand

TN: Total Nitrogen Total Nitrogen

TP: Total Phosphorus

FA: Free Ammonia Free Ammonia

FNA: Free Nitrous Acid

MLSS: Mixed Liquor Suspended Solid Activated Sludge Concentration

SDNR: Specific Denitrification Rate

SNR: Specific Nitrification Rate Specific Nitrification Rate

AUR: Ammonium Uptake Rate Ammonia Removal Rate

Example

1. Livestock Wastewater Treatment

And the inlet flow 100m ³ / d, an inflow BOD 6,000㎎ / L, and the concentration of the suspended solids and the inlet 6,000㎎ / L, the inlet and the concentration of total nitrogen 4,000㎎ / L, a concentration of ammonium nitrogen inlet 3300 Mg / L and the concentration of influent total phosphorus is 250 mg / L.

2. The first aerobic oxidation tank

As 50% of the storage tank 10 is distributed to the first denitrification tank, 50 m ³ / d of raw water, which is 0.5Q, flows into the first aerobic oxidation tank 20. In addition, since the ratio of BOD: N: P in cell synthesis is 100: 5: 1, the concentration of nitrogen is 300 mg / L at an inflow BOD of 6,000 mg / L. Therefore, the pure nitrogen nitrate is 150 kg and the loading of nitrogen is 0.5 kg. The volume of the reaction tank is 300 m ³ , and the actual concentrations of nitrate nitrogen and BOD are 600 mg / L and 80 mg / L, respectively. Becomes

0.5Q inflow (50m ³ / d)

Cell Synthesis BOD: N: P = 100: 5: 1 = 6000: N: P

N synthesis = 300 mg / L, P synthesis = 60 mg / L

Nitrate target N = (3300-300) = 3000mg / L ⇒3000mg / L * 50m ³ = 150kg

Nitriding efficiency 80% when N loading is 0.5kg / m ³

0.5kg / m ³ = N loading is 0.5kg / m ³ ⇒V = 300m ³

(HRT 6day for inflow 0.5Q)

NH ₄ -N _eff = 3000 mg / L * 20% = 600 mg / L

BOD _eff = = 80 mg / L (K _m = 0.5 per hour)

3. First anoxic denitrification tank using its own carbon source

0.5Q of the first aerobic oxidizing tank 20, which is directly distributed and flowed in from the storage tank 10, and the first aerobic oxidizing tank 20 having the nitrification efficiency of 80% are combined, so that the pure denitrification target nitrogen becomes 120 kg. In addition, the inflow BOD is 304 kg including the first aerobic oxidation tank 20. Therefore, the actual concentration of ammonia nitrogen is 1800 mg / L, and the BOD is 640 mg / L.

0.5Q (50m ³ ) Raw Water + 0.5Q (50m ³ ) Nitrous Oxide Outflow = 100m ³

Nitrogen to be denitrated = (3000-600) = 2400 mg / L = 2400 mg / L * 50 m ³ = 120 kg (1200 mg / L)

HRT = '0.85day'∼⇒1day (V = 100m ³ )

Inflow ^{BOD = 80㎎ / L * 50m 3} + 6000㎎ / L * 50m 3 = 304kg BOD

NH ₄ -N _eff = = 1800 mg / L

BOD _eff = = 640 mg / L

4. No.2 Aerobic Oxidation Tank

In this reactor, nitrification occurs relatively fast in the absence of organic matter. When the concentration of ammonia nitrogen introduced is 1800 mg / L and the N loading is 0.5kg / m ³ , the nitrification efficiency is 90%. The volume of the reactor is 360 m ³ , and the actual concentrations of nitrate nitrogen and BOD are 180 mg / L and 13 mg / L, respectively.

Inflow NH ₄ -N = 1800 mg / L

Nitrating efficiency 90% when N loading is 0.5kg / m ³

0.5kg / m ³ = ⇒V = 360m ³ (HRT = 3.6day) ⇒4day

NH ₄ -N _eff = 1800 * 10% = 180 mg / L

BOD _eff = = 13 mg / L

5. Second anoxic denitrification tank using external carbon source

The actual denitrification target of this reactor is 162 kg when 180 mg / L is not nitrified from 1800 mg / L of ammonia nitrogen introduced into the second aerobic oxidation tank 40, and thus, the external carbon source administered is 324 kg. BOD is injected.

Denitrification target = 1800-180 = 1620mg / L = 1620mg / L * 100m ³ = 162kg

HRT = '1.16day' to ⇒ 1.5day (150m ³ )

6. Precipitation Tank

Selective administration of Alum, Ferric Chloride, etc. to the reactor or the inflow channel to precipitate and remove not only phosphorus but also some of the unremoved nitrogen. During cell synthesis, the inlet BOD is 6000mg / L and the concentration of phosphorus 60mg / L As a result, the total phosphorus to be settled is 19kg, and the chemical requirement is 6.65kg.

Cell synthesis amount = 60 mg / L

Sedimentation target = 250-60 = 190mg / L = 190mg / L * 100m ³ = 19kg

Chemical requirement = 0.35kgFe ³⁺ / kgP _removed * 19kgP = 6.65kgFe ³⁺

HRT = 12 hours

7. Final discharge water quality

The concentration of the treated water discharged from the settling tank 60 is shown as follows.

BOD _eff = 30 mg / L or less

TN _eff = 180 mg / L

TP _eff = 8 or less

SS _eff = 30 or less

Total stay time = storage tank (1.5 days) + first oxidation tank (3 days) + denitrification tank (1 day) + second oxidation tank (4 days) + denitrification tank (1.5 days) + sedimentation (0.5 days) = 11.5 days

As described above, the biological nitrogen removal method of the high concentration wastewater of the present invention and the apparatus thereof are additionally supplied with its own carbon source in accordance with the ratio of influent organic matter / nitrogen and nitridated in the first aerobic oxidizing tank, and the first anoxic denitrification tank. Nitrates the influent wastewater, which is denitrified to its own carbon source, and relatively low in organic concentration, in the second aerobic oxidizer, and denitrified using a separate external carbon source in the second anoxic oxidizer, thereby reducing the external carbon source, oxygen demand, and residence time. It will be effective to reduce the.

In addition, the present invention is that the aerobic oxidation tank and the anoxic denitrification tank are separated from each other to operate in a continuous manner to improve the denitrification efficiency.

In addition, the present invention is not provided with a conveying line is to simplify the system and to reduce the maintenance costs required for its operation is to be effective.

In addition, the present invention has the effect that does not require a separate treatment cost by operating by injecting into the reaction tank as it is without separating the solids of the raw water during operation.

Claims (13)

In the biological nitrogen removal device of high concentration wastewater, A storage tank 10 for storing inflow water to adjust the inflow load and to adequately supplement alkalinity; A first aerobic oxidizing tank (20) for inhibiting Nitrobacter's activity by FA (free ammonia; NH ₃ ) of the raw water constantly introduced by the storage tank (10) to control nitrification to nitrite nitrogen; A first anoxic denitrification tank (30) for denitrifying the inflow water nitrified with nitrite nitrogen in the first aerobic oxidation tank (20) by its own carbon source; An agent for oxidizing not only ammonia nitrogen contained in raw water in which organic matter decomposition occurs in the first anoxic denitrification tank 30 using organic carbon decomposition, but also ammonia not removed in the first aerobic oxidation tank 20 to nitrite nitrogen. An aerobic oxidation tank 40; A second anoxic denitrification tank (50) for denitrifying nitrous acid nitrogen oxidized in the second aerobic oxidation tank (40) by an external carbon source to be selectively administered; The biological nitrogen of the high concentration wastewater, characterized in that it comprises a sedimentation tank 60 for selectively removing the denitrified particulate nitrogen as well as phosphorus by selectively treating the denitrified raw water in the second anoxic denitrification tank (50) Removal device. The method of claim 1, Biological nitrogen removal apparatus of the high concentration wastewater, characterized in that the distribution to the first anoxic denitrification tank (30) so that denitrification can be made using the carbon source of the influent water from the storage tank (10). The method according to claim 1 or 2, The inflow amount distributed from the storage tank 10 to the first anoxic denitrification tank 30 is introduced at 25 to 75% of the inflow flow rate according to the SCOD / NH4 + -N ratio and the loading of ammonia nitrogen. Biological nitrogen removal device of high concentration wastewater. The method according to claim 1 or 2, Biological nitrogen removal apparatus of high concentration wastewater, characterized in that NaOH or NaHCO ₃ is administered to maintain the alkalinity / NH ₄ ^-- N ratio 7.14 to the storage tank (10). The method of claim 1, Biological nitrogen removal apparatus of high concentration wastewater, characterized in that the media (media) is selectively administered to maintain a stable nitrification to the second aerobic oxidation tank (40). The method according to claim 1 or 5, Biological nitrogen removal apparatus of high concentration wastewater, characterized in that the second aerobic oxidation tank 40 is selectively supplemented with alkaline (alkalinity). The method of claim 1, The settling tank (70) is a biological nitrogen removal apparatus of high concentration wastewater, characterized in that the aluminum sulfate (Alum), ferric chloride (Ferric Chloride) is selectively administered to remove the phosphorus. The method of claim 1, Biological nitrogen removal apparatus for high concentration wastewater, characterized in that the hydraulic retention time (HRT) is operated in the same manner as the sludge retention time (SRT), so no return facility is required. The method of claim 1, Sludge residence time (SRT) is a biological nitrogen removal device of high concentration wastewater, characterized in that 12 to 10 days depending on the influent. The method of claim 1, A biological nitrogen removal apparatus of high concentration wastewater, characterized in that for selectively controlling the nitrous oxidation efficiency so that the SCOD / NH ₄ ⁺ -N ratio is less than 2. In the biological nitrogen removal method of high concentration wastewater, Properly adjust SRT (or HRT) according to influent and temperature to prevent Nitrobacter acclimation to FA and denitrify by nitrification of nitrite nitrogen (NO ₂ -N). Oxidize to ₂ -N) and denitrify it first using an influent carbon source in anoxic state, and then the excess nitrogen is oxidized to nitrite nitrite (NO ₂ -N) in aerobic phase and then to external carbon source in anoxic state. Biological nitrogen removal method of high concentration wastewater, characterized in that the secondary denitrification using selectively. The method of claim 8, A method for removing biological nitrogen of high concentration wastewater, characterized in that the hydraulic retention time (HRT) is set to be equal to the sludge retention time (SRT) with 12 hours to 10 days depending on the influent. The method of claim 8, A method for biological nitrogen removal of high concentration wastewater, characterized in that selectively controlling the nitrous oxidation efficiency such that the SCOD / NH ₄ ⁺ -N ratio is less than 2.