JP2008049251A - Apparatus for removing nitrogen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for removing nitrogen in which a DHS (Down-flow Hanging Sponge) reactor and a sulfur denitrification tank are combined and used, which has excellent nitrification capacity and in which organic matter and nitrogen can be removed continuously and easily. <P>SOLUTION: The apparatus 1 for removing nitrogen is provided mainly with: a nitrification reaction tank 2 in which residual organic matter contained in the secondarily treated water 3 of sewage is decomposed/removed and ammonia nitrogen is nitrified and converted into oxidized nitrogen; and the sulfur denitrification tank 6 for removing nitrogen gas 5 from the nitrified water 4 so that the organic matter contained in the secondarily treated water 3 of sewage can be removed and nitrification and denitrification can be performed continuously. The DHS reactor being one kind of water-sprinkling porous filter beds which is formed by using a spongy filter bed main body 8 consisting of a porous base stock is used as the nitrification reaction tank 2. The nitrified water 4 having a low C/N ratio can be discharged from the DHS reactor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a nitrogen removal apparatus, and more particularly to a nitrogen removal apparatus that can be used for so-called "high-level treatment" for treating sewage such as sewage secondary treated water containing organic matter, ammoniacal nitrogen, and phosphorus. It is.

  Conventionally, sewage such as domestic wastewater discharged from ordinary households or industrial wastewater (drainage) discharged from various factories, etc. is sewage that removes harmful substances contained in these sewage in advance before discharging into rivers. Processing is performed. However, in ordinary sewage treatment, organic substances still remain, nitrogen compounds mainly composed of ammonia nitrogen, or phosphorus compounds often remain. In general “sewage treatment”, these are completely removed. It is known that you can't.

  Release of treated water containing a large amount of ammonia nitrogen and the like to closed water areas such as rivers and lakes will eutrophicate the water areas, causing water pollution and ecology such as living organisms. The possibility of causing the destruction of the system is increased. Then, the advanced treatment which performs the process which further purifies the treated water which processed sewage etc. primarily by the aerobic activated sludge method, and removes the above-mentioned organic substance, ammonia nitrogen, etc. is performed. At this time, the advanced treatment decomposes and removes organic substances contained in the sewage, and also nitrifies a nitrification reaction tank that nitrifies ammoniacal nitrogen into oxidized nitrogen, and a denitrification tank that converts nitrified oxidized nitrogen into nitrogen gas, The two-stage processing is performed by the above, and the processing object is efficiently removed in each tank.

Here, the nitrification reaction tank can be roughly classified into two types depending on the difference in the method, and specifically, can be classified into a biofilm method and an activated sludge method. Examples of the biofilm method include, for example, a rotating plate contact method, a contact aeration method, a sprinkling filter method, and the like. On the other hand, examples of the activated sludge method include a long time aeration method and a standard activated sludge method. Etc. are known. Here, various types of filter media (filter beds) forming a part of the nitrification reaction tank used for nitrification have been developed according to the removal performance, the removal conditions, and the like. For example, polymer-processed zeolite, special charcoal, and polyethylene glycol are known. However, these filter media are generally required to keep microorganisms acting in the nitrification reaction at a concentration as high as possible, and any form or form is best for organic matter depending on various conditions. In many cases, it is not clear whether or not the decomposition action is exhibited. Here, as a general reaction performed in the nitrification reaction tank, as shown in the following formula (1), ammonia nitrogen is converted to oxidized nitrogen.

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

  Here, as shown in the above formula (1), the presence of oxygen is indispensable in order to convert ammoniacal nitrogen into oxidized nitrogen. In a general immersion type nitrification reaction tank, microorganisms are in contact with each other. Aerobic forcing oxygen (air) into the water by a blower is performed on the filter bed to activate the microorganisms.

  On the other hand, there has been proposed a nitrification reaction tank that does not require aeration and that can reliably support a group of microorganisms adhered to a filter bed. More specifically, a sponge-like object using a porous material (for example, foamed polyurethane resin) is cut into a polygonal shape such as a triangle or a quadrilateral, and is supported by hanging like a curtain. A DHS reactor (Down-flow Hanging Sponge Reactor) is used as a nitrification reaction tank that drops treatment target water (sewage secondary treated water, etc.) from the upper part and collects treated water from a discharge port provided at the lower end of the filter bed. Has been developed (see, for example, Patent Document 1).

  According to this, the water to be treated introduced (dropped) from the introduction port provided in the upper part travels through the sponge-like object that is the filter bed and gradually flows downward. At this time, since the filter bed has a porous property, a large amount of air (oxygen) easily enters the voids, so that the water to be treated comes into contact with a large amount of air (oxygen) when flowing down. As a result, forced (artificial) aeration as in the conventional method is not necessary. Furthermore, compared to the conventional method, a group of microorganisms having a microorganism concentration of 10 times or more can be supported in the filter bed of the sponge, whereby untreated organic matter is hardly discharged from the discharge port. .

On the other hand, as a denitrification tank for converting oxidized nitrogen into nitrogen gas and removing nitrogen from the water to be treated, for example, a heterotrophic denitrification tank or the like can be used. Here, the heterotrophic denitrification tank is performed on the nitrified water that has been subjected to nitrification treatment generated by the above-described nitrification reaction tank, and the reaction mainly represented by the following formula (2) is performed. . Here, in order to convert the oxidized nitrogen into nitrogen gas, it is necessary to add an organic substance such as methyl alcohol to the nitrification water as an electron donor as shown in the following formula (2). In addition, as another treatment method, a method using a sulfur denitrification tank for treating groundwater, drinking water, or the like is known.

(2) 6NO ₃ ⁻ + 5CH ₃ OH
→ 3N ₂ ↑ + 5CO ₂ ↑ + 7H ₂ O + 6OH ⁻

JP-A-11-285696

  However, in the case of the denitrification treatment using the heterotrophic denitrification tank described above, it was necessary to add an organic substance such as methyl alcohol to the nitrification water treated by the nitrification reaction tank as a previous step. In other words, in the nitrification reaction tank, it was necessary to add an appropriate amount of organic matter again in order to recover nitrogen gas even though the organic matter was once removed. In particular, when there is too much supply of organic matter, the organic matter that has not been consumed due to the reaction with oxidized nitrogen is surplus and mixed in the treated water discharged from the heterotrophic denitrification tank. For this reason, removal of organic substances by the nitrification reaction tank in the previous stage may be wasted. On the other hand, when the supply of the organic matter is too small, even if the organic matter is completely consumed, oxidized nitrogen remains, and nitrogen cannot be completely removed from the nitrification water. For this reason, the use of heterotrophic denitrification tanks requires that the amount of organic matter to be supplied be set strictly or that the circulation ratio for circulating these be appropriately set.

  On the other hand, the sulfur denitrification tank does not need to supply organic matter unlike the heterotrophic denitrification tank described above, and the treatment of nitrification water is relatively easy. However, as described above, the sulfur denitrification tank is mainly used for water having a low organic substance / oxidized nitrogen ratio (C / N ratio) such as groundwater and drinking water, and is a secondary treated water of sewage. It was rarely applied to water having a relatively high ratio of organic substances such as.

  Therefore, in view of the above circumstances, the present invention uses a DHS reactor having a high organic matter removal performance as a nitrification reaction tank, and further uses a sulfur denitrification tank as a denitrification tank, and combines them to provide excellent nitrification properties. An object of the present invention is to provide a nitrogen removing apparatus capable of continuously and easily removing organic substances and suspended substances and removing nitrogen.

  In order to solve the above-mentioned problem, the nitrogen removing apparatus according to the present invention uses a decomposition target and a nitrifying action of aerobic microorganisms to treat water containing organic matter and ammoniacal nitrogen to decompose and remove the organic matter. And a nitrification reaction tank for performing nitrification of the ammonia nitrogen to oxidized nitrogen, and a nitrification water containing the oxidized nitrogen nitrified by the nitrification reaction tank with a sulfur component that functions as an electron donor. And a sulfur denitrification tank for performing a denitrification treatment for contacting the main sulfur treatment agent and converting the oxidized nitrogen contained in the nitrification water into nitrogen gas.

  Therefore, according to the nitrogen removing apparatus of the present invention, a nitrification reaction tank for performing nitrification treatment on water to be treated containing organic matter and ammonia nitrogen is combined with a sulfur denitrification tank discharged through the nitrification reaction tank. Thus, organic substances and nitrogen can be removed relatively easily. As a result, compared to conventional heterotrophic denitrification tanks, there is no need to supply organic substances when converting from oxidized nitrogen to nitrogen gas, and the circulation ratio of these supply processes and the amount of organic substances to be supplied is adjusted. It is not necessary to perform complicated processing such as.

  Furthermore, the nitrogen removing apparatus according to the present invention has, in addition to the above configuration, “the nitrification reaction tank discharges the treated nitrification water and introduces the treated nitrification water, and is provided below the introduction port. Formed by a porous material having a plurality of voids capable of supporting the aerobic microorganisms, suspended or supported by the introduction port, and connecting between the introduction port and the discharge port. A porous filter main body for decomposing and removing the organic matter by flowing down the water to be treated introduced from the introduction port to the discharge port and converting the ammonia nitrogen to the oxidized nitrogen A watering-type porous filter bed equipped with "may be used."

  Therefore, according to the nitrogen removing apparatus of the present invention, a sprinkling porous filter bed is used as a nitrification reaction tank for performing nitrification treatment. Here, as the sprinkling porous filter bed, the above-described DHS reactor or the like can be used. Thereby, in the nitrification reaction tank, organic substances can be almost completely removed, and the nitrification rate can be almost 100%. As a result, since the nitrification water discharged from the nitrification reaction tank has a low C / N ratio, the nitrification water can be directly introduced into the sulfur denitrification tank. In other words, the sulfur denitrification tank, which was previously only capable of treating only high-quality treatment water (nitration water) such as groundwater, was nitrified with a relatively large amount of organic matter such as sewage secondary treated water. Even nitrification water can be denitrified with sulfur.

  Furthermore, according to the nitrogen removing apparatus of the present invention, in addition to the above-described configuration, “the nitrification water provided between the nitrification reaction tank and the sulfur denitrification tank and discharged from the nitrification reaction tank is supplied to the sulfur denitrification tank. The sulfur denitrification tank is provided in the vicinity of the lower end, and is provided in the vicinity of the upper end of the secondary inlet for introducing the nitrification water fed by the liquid pump. A nitrogen gas discharge port that discharges nitrogen gas generated by the denitrification process and a treated water discharge port that discharges the treated water after the denitrification process and a denitrification treatment space connected to each other are formed inside. The substantially cylindrical denitrification tank main body, and the sulfur-based treatment agent that fills at least a part of the denitrification treatment space and functions as an electron donor for the nitrification water ”. It is configured.

Therefore, according to the nitrogen removing apparatus of the present invention, the nitrification water fed from the nitrification reaction tank via the liquid feed pump is introduced from the secondary inlet near the lower end of the sulfur denitrification tank and is provided near the upper end. The gas is discharged separately through the nitrogen gas outlet or the treated water outlet. Here, since the nitrification water is introduced from the lower end of the sulfur denitrification tank, the nitrification water necessarily comes into contact with the sulfur-based treatment agent functioning as an electron donor in which the internal denitrification treatment space is at least partially filled. It will be. Thereby, gas is generated by the reaction according to the following formula (3).

(3) NO ₃ ⁻ + 5 / 8S ₂ O ₃ ²⁻ + 1 / 8H ₂ O

→ 1 / 2N ₂ ↑ + 5 / 4SO ₄ ^2- + 1 / 4H ⁺

  The reaction tank has an inlet for introducing the water to be treated, an outlet for discharging the treated nitrification water, a discharge port provided below the inlet, and a plurality of voids capable of supporting the aerobic microorganisms. The organic material is decomposed by being formed of a porous material, connecting the inlet and the outlet, and dropping the treatment target water introduced from the inlet to the outlet, It is also possible to use a sprinkling porous filter bed having a filter bed main body for converting the ammonia nitrogen to the oxidized nitrogen.

  Here, the nitrification reaction tank is a reaction capable of converting ammonia nitrogen contained in water to be treated such as secondary treated water of sewage into oxidized nitrogen such as nitrate ions using the action of oxygen and microorganisms. Is what you do. Here, since details of the method of the nitrification reaction tank and the like have already been described, for example, a sprinkling filter type DHS reactor can be employed, although omitted. Thereby, the water to be treated introduced from the upper part of the nitrification reaction tank propagates through the sponge-like filter bed suspended and supported in a curtain shape as a part of the DHS reactor, and gradually arrives at the lower discharge port. As a result, the water to be treated, introduced from the inlet and gradually reaching the outlet by dripping, contains a large amount of air due to the porous filter bed, and the organic matter contained by the action of microorganisms is almost completely contained. Can be removed.

  As an effect of the present invention, as described above, by adopting a DHS reactor which is a kind of sprinkling porous filter bed as a nitrification reaction tank, nitrification water discharged from the discharge port contains almost no organic matter. It is possible to perform treatment of advanced sewage secondary treated water or the like. In particular, there is no need for aeration forcibly sending oxygen (air) as in the conventional method, and energy saving and cost reduction can be achieved.

  Further, since the nitrification reaction of ammonia nitrogen can be carried out almost 100%, the nitrification water contains almost no ammonia nitrogen. Therefore, if the nitrification water having such a low C / N ratio is used, nitrogen can be removed by a sulfur denitrification tank that is simple and excellent in operability. As a result, by combining the nitrification reaction tank and the sulfur denitrification tank by the DHS reactor, it is possible to continuously perform the removal of organic substances, nitrification of ammonia nitrogen, and nitrogen gasification of oxidized nitrogen.

  Next, the nitrogen removal apparatus 1 of this embodiment is demonstrated based on FIG.1 and FIG.2. Here, FIG. 1 is an explanatory view schematically showing the schematic configuration of the nitrogen removing apparatus of the present embodiment, and FIG. 2 is an explanatory view schematically showing the configuration of the filter bed body 8 and the concept of nitrification treatment. . Here, the nitrogen removing apparatus 1 of the present embodiment adds ammonium chloride and sodium hydrogen carbonate in predetermined amounts to the septic tank treated water obtained by treating general waste water by the aerobic activated sludge method as the treatment target water, It illustrates about what treats the adjusted sewage secondary treated water 3. FIG. In the nitrogen removal apparatus 1, activated sludge was used as seeding. Moreover, the nitrogen removal apparatus 1 of this embodiment is processed under the temperature range of room temperature 10 degreeC-20 degreeC. Here, the sewage secondary treated water 3 corresponds to the water to be treated of the present invention.

  The nitrogen removing apparatus 1 of the present embodiment will be described in detail. As shown in FIG. 1, organic substances contained in the sewage secondary treated water 3 are decomposed and removed, and ammonia nitrogen is nitrified and converted to oxidized nitrogen. And a sulfur denitrification tank 6 for removing nitrogen gas 5 from the nitrification water 4 treated in the nitrification reaction tank 2.

  More specifically, the nitrification reaction tank 2 is connected to an inlet 7 for introducing the sewage secondary treated water 3 from above and one end of the inlet 7, and gradually introduces the introduced sewage secondary treated water 3. A sponge-like filter bed main body 8 to be flowed down and provided near the lower end of the filter bed main body 8, by flowing down the filter bed main body 8, organic substances contained in the sewage secondary treated water 3 are removed, and ammonia nitrogen is further added. A discharge port 9 for discharging the nitrification water 4 converted into oxidized nitrogen is mainly provided. Here, the filter bed body 8 uses a foamed urethane resin having a plurality of voids as a material, and a plurality of triangular prism sponges 8a (cross-sectional area: 0) cut to have a polygonal cross section (here, a triangular shape). .50 square centimeters, width: 20 centimeters, hole diameter: 0.56 millimeters), and the vinyl chloride resin plate 8b is bonded to each other while maintaining a slight distance between the upper and lower sides of each other to form a curtain. (See FIG. 2). Then, the upper end 10 of the filter bed main body 8 is connected to the introduction port 7, so that the filter bed main body 8 is suspended and supported by the introduction port 7. As a result, a DHS reactor having a sponge gap volume of 3.0 liters and a total height of 165 centimeters is formed.

  Moreover, since this urethane foam resin is formed of a soft material, it can be easily crushed by pressing the surface and can easily return to its original state by releasing the pressing. In addition, in order to prevent wind etc. hitting the filter bed main body 8 supported by suspension and moving the lower end 11 side of the filter bed main body 8, a part of the lower end 11 and a part of the discharge port 9 are connected, and the wind It may be one that suppresses movement (not shown). Moreover, in order to guide the sewage secondary treated water 3 to the introduction port 7, a commercially available liquid feed pump (not shown) may be provided.

  Therefore, when the sewage secondary treated water 3 is introduced from above, the sewage secondary treated water 3 gradually permeates into the inside of the porous (in other words, sponge-like) filter bed body 8, and the triangle It will flow down along the shape of the skeleton (see arrows A and B in FIG. 2). At this time, while slowly flowing down, it comes into contact with the surrounding oxygen O, and sufficient oxygen O is taken into the inside. And the aerobic microorganisms 12 previously attached to the sponge decompose the residual organic matter 13 contained in the sewage secondary treated water 3 by contacting with the sewage secondary treated water 3 to carbon dioxide or water. Along with the conversion, ammoniacal nitrogen can be converted to oxidized nitrogen according to the above formula (1).

  On the other hand, the sulfur denitrification tank 6 includes a secondary inlet 14 for introducing the nitrification water 4 treated by the nitrification reaction tank 2 and a nitrogen gas outlet for discharging the nitrogen gas 5 generated by the denitrification process. 16 and a denitrification treatment space provided with three entrances and exits of the treated water discharge port 18 for discharging the treated water 17 subjected to the denitrification treatment to the outside, and connected to the respective entrances 14, 16, and 18. The denitrification tank body 20 having a substantially cylindrical shape 19 formed therein, the sulfur-based treatment agent 21 filled in the denitrification treatment space 19, and the nitrogen gas discharge port 16 are connected via a gas pipe 22 to generate The nitrogen gas 5 is trapped and a trap 24 for preventing oxygen (air) from entering the sulfur denitrification tank 6 from the outside is provided. Moreover, between the nitrification reaction tank 2 and the sulfur denitrification tank 6, the treated nitrification water 4 is introduced from the lower end side of the sulfur denitrification tank 6, and is used for forcibly discharging from the upper end side. A liquid feed pump 25 is attached.

  Next, an example of nitrogen removal of the sewage secondary treated water 3 using the nitrogen removing apparatus 1 of the present embodiment will be described. First, the sewage secondary treated water 3 adjusted from the inlet 7 of the nitrification reaction tank 2 is introduced. Thereby, the organic substance and ammonia nitrogen contained in the sewage secondary treated water 3 are decomposed | disassembled by the effect | action of the aerobic microorganism 12, and it converts into oxidized nitrogen, such as a nitrate ion, by the effect | action mentioned above.

  Table 1 shows the measured values before inflow (introduction) and after outflow (discharge) according to the treatment status of the sewage secondary treated water 3 in the nitrification reaction tank 2 of the nitrogen removing apparatus 1 of the present embodiment. Here, from the start of operation of the nitrification reaction tank 2 to the 257th day, ammonium chloride was added at a rate of 20 mgN / L and after the 258th day, 40 mgN / L. The HRT (hydraulic residence time) was 2 hr from the start of operation to the 85th day, and 1 hr after 86 days. Furthermore, from the start of operation to the 346th day, control is performed so that the room temperature is 20 ° C. and from the 347th day to the 437th day, the room temperature is 15 ° C., and after the 438th day, the room temperature is not controlled and the temperature in the winter season (room temperature 15 (Below ℃).

  According to this, it is shown that the total BOD of the nitrification water 4 discharged from the discharge port 9 of the nitrification reaction tank 2 is 1 to 2 mg / L regardless of the room temperature, and the water quality of the nitrification water 4 is It was confirmed that it was extremely stable. Moreover, according to Table 1, it was shown that average BOD / CODcr is 0.33 in the sewage secondary treated water 3 before the treatment, whereas it is 0.14 in the nitrification treated water 4. That is, only the organic matter that is difficult to be decomposed by the aerobic microorganism 12 remains in the nitrification water 4, and the organic matter that can be decomposed by the aerobic microorganism 12 is almost consumed in the nitrification reaction tank 2. Is shown. Thereby, it was confirmed that the residual amount of the organic substance contained in the nitrification water 4 is extremely low.

  Moreover, the average total nitrogen of the sewage secondary treated water 3 was 63 mgN / L, of which ammonia nitrogen was 35 mgN / L. And as mentioned above, the addition amount of ammonium chloride was doubled after the 258th day from the start of operation, and the content of ammoniacal nitrogen contained in the sewage secondary treated water 3 was increased, but an average of 3 mgN / L The ammonia nitrogen removal rate showed a high result of 90% or more. The removal rate of ammonia nitrogen hardly changes even when the room temperature around the nitrification reaction tank 2 changes, that is, even under conditions of room temperature of 15 ° C. or less in winter and the like. It was confirmed that the activity of the aerobic microorganisms 12 adsorbed on the filter bed main body 8 can be exhibited even at a low temperature of 15 ° C. or lower. Further, as shown in Table 1, the presence of nitrite nitrogen was hardly confirmed, and it was confirmed as nitrate nitrogen. That is, ammonia nitrogen is completely oxidized. As a result, it was shown that the decomposition reaction by the aerobic microorganisms 12 was sufficiently carried out in sufficient contact with oxygen in the sponge-like filter bed main body 8 while flowing down from the inlet 7 to the outlet 9. .

  As shown above, by adopting the DHS reactor as the nitrification reaction tank 2, there is no need for forced aeration, high organic substance removal performance with almost no maintenance, and ammonia nitrogen is nitrate nitrogen. And excellent nitrification performance for oxidation to (oxidized nitrogen). As a result, the nitrification-treated water 4 discharged from the discharge port 9 can be treated water with almost no organic matter contained in the oxidized nitrogen, that is, a low C / N ratio. Therefore, the nitrogen removal process by the sulfur denitrification tank 6 mentioned later becomes possible.

  Thereafter, the nitrification water 4 is delivered to the denitrification treatment space 19 through the secondary introduction port 14 near the lower end of the sulfur denitrification tank 6 via the liquid feed pump 25. Here, the denitrification treatment space 19 is filled with a sulfur-based treatment agent 21 mainly composed of sulfur that functions as an electron donor for donating electrons to the nitrification treated water 4. Then, the nitrification water 4 sent from the secondary inlet 14 near the lower end to the denitrification space 19 is slowly pushed upward in the denitrification space 19 by the pressure of the liquid feed pump 25. At this time, by contacting with the sulfur-based treatment agent 21, the reaction is performed in the denitrification treatment space 19, and the oxidized nitrogen (nitric nitrogen) and the sulfur component react to generate nitrogen gas 5. The generated nitrogen gas 5 is discharged to the outside through a nitrogen gas discharge port 16 provided in the vicinity of the upper end of the sulfur denitrification tank 6. In addition, the generated nitrogen gas 5 is trapped in the middle of the gas pipe 22 extended from the nitrogen gas discharge port 16, and air (a trap 24 for preventing oxygen from entering) is provided in the sulfur denitrification tank 6 from the outside. On the other hand, the treated water 17 from which the nitrogen gas 5 has been removed by sulfur is discharged to the outside through the treated water discharge port 18. Here, the discharged treated water 17 is discharged from the nitrification treated water 4 described above. In the sulfur denitrification tank 6, organic matter or the like has not been added as in the prior art, so there is a particular problem even if it is discharged as it is as the stable treated water 17 to the outside. Absent.

  Here, when the water temperature, pH, organic substance concentration, and ammonia nitrogen concentration of the water to be treated (sewage secondary treated water 3) that can be treated in the nitrogen removing apparatus 1 of the present invention are exemplified, the water temperature is 10 to 30 ° C., The pH can be targeted in the range of 7 to 8.5, and the organic matter concentration contained in the water to be treated is 0 to 50 mg BOD / L, 0 to 100 mg CODcr / L, and the concentration of ammoniacal nitrogen is 100 mg N / L. It can be: In addition, when pH does not correspond to the said prescription | regulation range, it is also possible to adjust so that it may become the said range using a known pH adjuster.

  And although the nitrification reaction tank 2 showed what made HRT into the range of 1-2 hr in the said Example, it considers the whole processing time and it is preferable to set it to the range of 1-3 hr. Similarly, the treatment time of the sulfur denitrification tank 6 is preferably set in the range of 2 to 10 hr in consideration of the treatment time and the removal rate of the nitrogen gas 6. And the nitrification process water 4 discharged | emitted from the nitrification reaction tank 2 can make organic substance density | concentration 3 mgBOD / L or less, and also can suppress ammonia nitrogen concentration to 5 mgN / L or less.

  On the other hand, the treated water 17 discharged from the sulfur denitrification tank 6 does not require the addition of an organic substance as an electron donor as in the conventional heterotrophic denitrification tank, so the organic substance concentration does not change, and 3 mg BOD / L You can leave it below. And the sum total of the density | concentration of the oxidized nitrogen (or nitrate nitrogen) and ammonia nitrogen density | concentration converted by the nitrification reaction tank 2 can be 5 mgN / L or less.

  As described above, according to the nitrogen removing apparatus 1 of the present embodiment, a DHS reactor that does not require aeration can be used as the nitrification reaction tank 2, and the nitrification water 4 having a low C / N ratio can be discharged. Furthermore, by using a sulfur denitrification tank 6 that is suitable for water to be treated with a low C / N ratio and that can perform denitrification treatment relatively easily, organic matter removal, nitrification, and denitrification of the sewage secondary treated water 3 are performed. Can be performed continuously. Thereby, compared with the past, the operation and management of the nitrogen removing apparatus 1 can be simplified, and the maintenance cost required for the nitrogen removing process can be reduced. Moreover, since the organic matter and nitrogen are removed from the treated water 17 discharged to the outside, the discharge destination rivers and lakes are not eutrophied, and there is no possibility of destroying the ecosystem and the natural environment.

  The present invention has been described with reference to preferred embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention as described below. And design changes are possible.

  That is, in the nitrogen removal apparatus of the present embodiment, the DHS reactor has been described as the nitrification reaction tank 2, but the present invention is not limited to this, and the low C / N nitrification water 4 that can be treated in the sulfur denitrification tank 6. If it can discharge | emit, it will not specifically limit. However, a DHS reactor that can treat the sewage secondary treated water 3 with a low cost and a stable water quality that does not require aeration seems to be particularly suitable. Moreover, in this embodiment, although what processed the sewage secondary treated water 3 containing a residual organic substance was shown, it is not limited to this, You may process the treated water containing another organic substance. .

  Further, the DHS reactor employed in the nitrogen removing apparatus 1 of the present embodiment mainly comprises the filter bed main body 8 formed from a triangular prism-like sponge, but the shape, size, etc., of the filter bed main body 8 of such a DHS reactor, etc. Is not particularly limited. It can be appropriately changed according to the type, component, HRT, etc. of the water to be treated.

It is explanatory drawing which shows typically schematic structure of a nitrogen removal apparatus. It is explanatory drawing which showed typically the structure of the filter bed main body, and the concept of nitrification processing.

Explanation of symbols

1 Nitrogen removal equipment 2 Nitrification reaction tank (sprinkling porous filter bed)
3 Sewage secondary treated water (treated water)
4 Nitrified water 5 Nitrogen gas 6 Sulfur denitrification tank 7 Inlet 8 Filter bed body 9 Outlet 12 Aerobic microorganism 13 Residual organic matter (organic matter)
14 Secondary inlet 17 Treated water 19 Denitrification treatment space 20 Denitrification tank body 21 Sulfur-based treatment agent

Claims (3)

Nitrification reaction in which water to be treated containing organic matter and ammonia nitrogen is decomposed and removed by utilizing the decomposition and nitrification of aerobic microorganisms, and the nitrification of ammonia nitrogen to oxidized nitrogen is performed. A tank,
The oxidized nitrogen contained in the nitrified water is brought into contact with the nitrified water containing the oxidized nitrogen nitrified by the nitrification reaction tank, with a sulfur treating agent mainly comprising a sulfur component functioning as an electron donor. And a sulfur denitrification tank for performing a denitrification process for converting the gas into nitrogen gas. The nitrification reactor is
Porous material having a plurality of voids capable of supporting the aerobic microorganisms, an introduction port for introducing the treatment target water, a discharge port for discharging the treated nitrification water, and a discharge port provided below the introduction port The suspension port is supported by or filled in the introduction port, the connection between the introduction port and the discharge port, and the water to be treated introduced from the introduction port flows down to the discharge port, The sprinkling type porous filter bed having a porous filter bed main body for decomposing and removing organic substances and converting the ammoniacal nitrogen to the oxidized nitrogen is used. Nitrogen removal equipment. Provided between the nitrification reaction tank and the sulfur denitrification tank;
A liquid feed pump for feeding the nitrification water discharged from the nitrification reaction tank to the sulfur denitrification tank;
The sulfur denitrification tank is
A secondary inlet for introducing the nitrification water fed by the liquid pump, provided near the lower end, a nitrogen gas outlet for discharging nitrogen gas generated by the denitrification process, and a denitrification process A substantially denitrification tank main body having a denitrification treatment space connected to a treated water discharge port for discharging treated water afterwards,
The said sulfur type processing agent with which it fills at least one part of the said denitrification processing space, and functions as an electron donor with respect to the said nitrification water is further provided, The Claim 1 or Claim 2 characterized by the above-mentioned. Nitrogen removal equipment.

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