JP4780553B2 - Water treatment method and apparatus for wastewater containing ammonia - Google Patents

Description

  The present invention relates to a water treatment method and apparatus for denitrifying wastewater (raw water) containing ammonia, and more particularly to a water treatment method and apparatus for ammonia-containing wastewater using a polyvinyl alcohol (PVA) gel carrier. It is.

  In general, there are many applications that require reduction of ammonia in wastewater, such as sewage, human waste, leachate for final disposal of garbage, and various industrial wastewater.

  Conventionally, various physicochemical treatments and biological treatment techniques have been studied and used as wastewater treatment techniques for the purpose of ammonia reduction. In general, ammonia is reduced by finally converting to safe nitrogen gas and then releasing it into the atmosphere. However, in many of these cases, the conversion speed is too slow and the reaction tank is huge, increasing the equipment cost. Even so, there is nothing that can be satisfied.

  Among such situations, biological nitrification and denitrification methods are most frequently used. In this case, ammonia-containing wastewater is treated under aerobic conditions, converted to nitrite by nitrite bacteria (typically Nitrosomonas), which is also an autotrophic bacterium, and then nitrate bacteria that is also an autotrophic bacterium. It is converted to nitric acid by (typically Nitrobacter). After that, it is treated under anaerobic conditions, and nitric acid is converted into nitrogen gas by other vegetative denitrifying bacteria using organic matter as a hydrogen donor. This process is most widely used at present, but a large amount of oxygen is consumed in the nitrification stage, resulting in excessive aeration power, and the use of organic substances such as methanol as a hydrogen donor in the denitrification stage. In addition to the problem of running costs such as an excessive amount of addition, the conversion rate of nitrification / denitrification is low, so there is also a problem in equipment costs.

  Under such circumstances, a highly efficient process called Anaerobic Ammonium Oxidation: anammox method has been proposed, where development of a highly efficient biological nitrogen removal method has been desired for many years. Practical application is actively promoted. In this process, only about half of the ammonia in the raw water is oxidized to nitrous acid, and this nitrous acid and the remaining ammonia are supplied to the denitrification reactor in an anaerobic condition by the autotrophic anammox bacteria. Then, a denitrification reaction in which ammonia becomes a hydrogen donor and nitrous acid becomes a hydrogen acceptor occurs, and both are converted to nitrogen gas and removed.

The stoichiometric formula of the denitrification reaction by this anammox bacterium has been proposed as shown in the following formula (1) and has been confirmed experimentally.

1.0 NH ₄ ⁺ +1.32 NO ₂ ⁻ +0.066 HCO ₃ + 0.13H ⁺ =
1.02N ₂ + 0.26NO ₃ ⁻ + 0.066CH ₂ O _0.5 N _0.15 + 2.03H ₂ O (1)
By the way, anammox microorganisms are anaerobic bacteria and have a very slow growth rate. For this reason, as a measure for preventing the bacterial cells from flowing out of the reaction tank, flocking, self-granulating method, utilization of a carrier and the like are considered. There are many types of carriers, but when a polyvinyl alcohol (PVA) gel carrier that has a proven record in biological water treatment is used, not only the surface of the carrier but also the inside of the carrier enters and grows, The utilization efficiency of the carrier can be increased.

Heretofore, prior patent documents related to a method for biologically denitrifying raw water by an anaerobic ammonia oxidation method (anammox method) include the following.
Japanese Patent Laid-Open No. 2003-53385 discloses a denitrification process in which raw water containing ammonia nitrogen is used in the presence of nitrite nitrogen, ammonia nitrogen is used as an electron donor, and nitrite nitrogen is used as an electron acceptor. When biologically denitrifying by the action of microorganisms, the denitrifying microorganisms are comprehensively fixed using a polymer gel material, and kept at a high concentration while maintaining high activity in the denitrification reaction tank, which is stable and efficient. A biological denitrification apparatus for performing a denitrification process is disclosed. Japanese Patent Application Laid-Open No. 2001-170681 discloses an ammonia and phosphorus-containing wastewater treatment method and an apparatus thereof. In the third step reaction tank, the treated water in the second step reaction tank is subjected to anaerobic conditions. Ammonia components and nitrous acid components in the liquid phase are converted into nitrogen gas by contacting with a microorganism group, and ammonia contained in the wastewater is removed. Japanese Patent Application Laid-Open No. 2001-170684 discloses an ammonia-containing wastewater treatment method and an apparatus therefor, in which the ammonia-containing wastewater introduced from outside the system in a first step reaction tank is subjected to microorganisms in an aerobic state. The ammonia component contained in the liquid phase is oxidized to nitrous acid in contact with the group, and the treated water in the first step reaction tank is brought into contact with the microorganism group in the second step reaction tank under anaerobic conditions. It describes that an ammonia component and a nitrous acid component contained in a liquid phase are converted into nitrogen gas.

  In the inventions described in the above Patent Documents 1 to 3, it is disclosed that anammox bacteria are held by a polyvinyl alcohol (PVA) gel carrier in an anaerobic ammonia oxidation method (anammox method) denitrification reaction tank. According to the conventional methods described in Patent Documents 1 to 3, in any case, depending on the operation status of the denitrification reaction tank, a biofilm (microorganism film) is formed on the surface of the carrier, so There is a problem that the body is difficult to enter and the advantages of the carrier may not be utilized.

  An object of the present invention is to solve the above-mentioned problems of the prior art and suppress the formation of a biofilm (microorganism film) on the surface of a carrier in a method of biological denitrification of raw water by an anaerobic ammonia oxidation method (anammox method). It can be used not only near the surface of the PVA gel carrier but also inside the carrier to grow and increase the use efficiency of the carrier, which can achieve highly efficient nitrogen removal. An object of the present invention is to provide a wastewater treatment method and apparatus.

  As a result of intensive studies in view of the above points, the present inventor has provided an anoxic tank filled with polyvinyl alcohol (PVA) gel carrier in the denitrification reaction tank by anammox bacteria, and the carrier flows by upward flow. As a fluidization condition, the fluidized bed is fluidized so that the fluidized bed expands by about 50 to 50%, so that the pump power can be reduced compared to a fluidized bed in which the entire carrier is completely fluidized. We found that it can be made smaller. Also, by restricting the circulating water inflow part of the denitrification reaction tank and increasing the flow rate of water at the circulating water inflow part of the denitrification reaction tank, the formation of biofilm on the surface of the carrier is suppressed, and the inside of the carrier is efficiently The present inventors have found that cells can be grown and nitrogen removal can be performed with high efficiency, and the present invention has been completed.

In order to achieve the above-mentioned object, the invention of the water treatment method for ammonia-containing wastewater according to claim 1 is characterized in that the raw water (drainage) containing ammonia nitrogen is treated with ammonia nitrogen in the presence of nitrite nitrogen. A denitrification reaction vessel for biological denitrification by a denitrification microorganism using nitrite nitrogen as a hydrogen acceptor, and the denitrification microorganism is fixed to a polyvinyl alcohol (PVA) gel carrier in the denitrification reaction vessel, A PVA gel carrier to which denitrifying microorganisms are fixed is a water treatment method for ammonia-containing wastewater that forms a fluidized bed that circulates in an upward flow in a denitrification reaction tank, and a circulating water inflow portion of the denitrification reaction tank characterized by the flow rate of the influent water and 9500~20000m / h, locally increase the flow state of PVA gel carrier, to destroy biofilms (biofilm) which is formed on the PVA gel carrier surface in It is.

The invention of the water treatment apparatus for ammonia-containing wastewater according to claim 2 is characterized in that the raw water (drainage) containing ammonia nitrogen is in the presence of nitrite nitrogen, ammonia nitrogen is a hydrogen donor, and nitrite nitrogen is hydrogen. A denitrification reaction vessel for biological denitrification by a denitrification microorganism as a receptor, the denitrification microorganism is fixed to a PVA gel carrier in the denitrification reaction vessel, and the PVA gel carrier to which the denitrification microorganism is fixed is: A water treatment device for ammonia-containing wastewater that forms a fluidized bed that circulates in an upward flow in a denitrification reaction tank, and a circulation water discharge nozzle is provided at the circulating water inflow portion of the denitrification reaction tank, By setting the flow rate of the influent water discharged from the water discharge nozzle into the denitrification reaction tank to 9500-20000 m / h, the flow state of the PVA gel carrier is locally increased and formed on the surface of the PVA gel carrier. Biofilm (microbe membrane There has been characterized in that it is destroyed.

The invention of the water treatment apparatus according to claim 3 is the water treatment apparatus for ammonia-containing waste water according to claim 2, wherein the circulating water discharge nozzle provided at the bottom of the denitrification reaction tank includes a cylindrical peripheral wall and and comprising a top wall connected to this upper end, the cylindrical wall of the circulation water Ikidode nozzle and Deana Ikido required number of circulating water that opens or one horizontal direction radially viewed from the plane provided It is characterized by being.

The invention of the water treatment device according to claim 4 is the water treatment device for ammonia-containing waste water according to claim 2, wherein the circulating water discharge nozzle provided at the bottom of the denitrification reaction tank circulates in the circulation pipe. and dispensing main pipe connected to the water inlet side end portion, it is constituted by a planar Yorimi branch connected to comb Te Ikido extraction tube to the dispensing main, required number that opens downwardly to the respective branch Ikido extraction tube It is characterized in that a circulating water discharge hole is provided .

The water treatment method for ammonia-containing wastewater according to the present invention is a dewatering process in which raw water (drainage) containing ammonia nitrogen is used in the presence of nitrite nitrogen, ammonia nitrogen as a hydrogen donor, and nitrite nitrogen as a hydrogen acceptor.窒微organism by provided with a denitrification tank for biological denitrification, dehydration窒微organism is fixed in polyvinyl alcohol (PVA) gel carrier in the denitrification reactor, PVA gel carrier with a fixed denitrifying organisms, de A method for water treatment of ammonia-containing wastewater forming a fluidized bed that circulates in an upward flow in a nitriding reaction tank, wherein the flow rate of inflow water at the circulating water inflow portion of the denitrification reaction tank is 9500 to 20000 m / h by, locally increase the flow state of PVA gel carrier, since it is intended to destroy biofilms (biofilm) which is formed on the PVA gel carrier surface, according to the present invention, the support surface The formation of biofilms can be suppressed, and not only in the vicinity of the surface of the carrier, but also by entering and growing inside the carrier, the utilization efficiency of the carrier can be increased and highly efficient nitrogen removal can be achieved. There is an effect that can be achieved.

In addition, since the carrier is a PVA gel carrier, according to the present invention, an anoxic tank filled with the PVA gel carrier is provided in the denitrification reaction tank by the anammox bacteria, and the PVA gel carrier is fluidized by upward flow. And by restricting the circulating water inflow part of the denitrification reaction tank and increasing the flow rate of water at the circulating water inflow part of the denitrification reaction tank, the formation of biofilm on the surface of the PVA gel carrier is suppressed, and the PVA gel The cells can be efficiently propagated inside the carrier, and there is an effect that nitrogen can be efficiently removed.

Moreover, in the water treatment method for ammonia-containing wastewater according to the present invention, the flow rate of the influent water in the circulating water inflow portion of the denitrification reaction tank is 9500 to 20000 m / h. The formation of biofilms can be suppressed, and not only in the vicinity of the surface of the carrier, but also by entering and growing inside the carrier, the utilization efficiency of the carrier can be increased and highly efficient nitrogen removal can be achieved. In addition, the power of the circulating water feed pump can be reduced, and the equipment scale of the denitrification reaction tank can be reduced.

The invention of the water treatment apparatus for ammonia-containing wastewater according to claim 2 is characterized in that the raw water (drainage) containing ammonia nitrogen is in the presence of nitrite nitrogen, ammonia nitrogen is a hydrogen donor, and nitrite nitrogen is hydrogen. A denitrification reaction vessel for biological denitrification by a denitrification microorganism as a receptor, the denitrification microorganism is fixed to a PVA gel carrier in the denitrification reaction vessel, and the PVA gel carrier to which the denitrification microorganism is fixed is: A water treatment device for ammonia-containing wastewater that forms a fluidized bed that circulates in an upward flow in a denitrification reaction tank, and a circulation water discharge nozzle is provided at the circulating water inflow portion of the denitrification reaction tank, By setting the flow rate of the influent water discharged from the water discharge nozzle into the denitrification reaction tank to 9500-20000 m / h, the flow state of the PVA gel carrier is locally increased and formed on the surface of the PVA gel carrier. Biofilm (microbe membrane Therefore, according to the present invention, the formation of a biofilm on the surface of the carrier can be suppressed, and the bacterial cells can enter and proliferate not only near the surface of the carrier but also inside the carrier. Therefore, it is possible to increase the utilization efficiency of the carrier and to achieve an effect that nitrogen removal can be performed with high efficiency.

The invention of the water treatment apparatus according to claim 3 is the water treatment apparatus for ammonia-containing waste water according to claim 2, wherein the circulating water discharge nozzle provided at the bottom of the denitrification reaction tank includes a cylindrical peripheral wall and and comprising a top wall connected to this upper end, the cylindrical wall of the circulation water Ikidode nozzle and Deana Ikido required number of circulating water that opens or one horizontal direction radially viewed from the plane provided Therefore, according to the present invention, by setting the discharge direction of the circulating water in the horizontal direction, an effect of creating a vortex and causing the carrier to flow violently is produced, thereby suppressing the formation of biofilm on the surface of the carrier. In addition to the vicinity of the surface of the carrier, the cells enter and grow inside the carrier, so that the utilization efficiency of the carrier can be increased and high-efficiency nitrogen removal can be achieved. .

The invention of the water treatment device according to claim 4 is the water treatment device for ammonia-containing waste water according to claim 2, wherein the circulating water discharge nozzle provided at the bottom of the denitrification reaction tank circulates in the circulation pipe. and dispensing main pipe connected to the water inlet side end portion, it is constituted by a planar Yorimi branch connected to comb Te Ikido extraction tube to the dispensing main, required number that opens downwardly to the respective branch Ikido extraction tube those circulating water Ikido Deana of is provided, according to the present invention, the circulating water, and dispensing main, circulation of this dispensing main connected Te plane Yorimi the comb branch Ikido extraction tube By discharging the water from the water discharge hole and setting the discharge direction of the circulating water downward, an effect of creating a vortex and a violent flow of the carrier is produced, thereby suppressing the formation of biofilm on the surface of the carrier. And the bacteria enter not only near the surface of the carrier but also inside the carrier, I'll be fertilized, to be able to enhance the utilization efficiency of the carrier, it may play a highly efficient nitrogen removal. Further, since the circulating water discharge hole is opened downward in each branch extraction pipe, there is an effect that the circulating water discharge hole is not easily blocked by the carrier .

  Next, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  1 and 2 are flow sheets showing a first embodiment of an apparatus for carrying out the water treatment method for ammonia-containing waste water of the present invention.

  Referring to FIG. 1, the water treatment method of the present invention is a method for treating waste water (raw water) containing ammonia, and the aeration tank (1) as a primary treatment tank is operated by operating a pump (not shown). Drainage is supplied from the drainage supply pipe (3). For example, activated sludge derived from a sewage treatment plant is put into the aeration tank (1). The bottom of the aeration tank (1) is provided with a diffuser pipe (aeration means) to which air is supplied by the operation of an air pump. In the aeration tank (1), a part of ammonia in the raw water is biologically produced by ammonia oxidizing bacteria. It is oxidized and oxidized to nitrite. The primary treated water after the reaction is discharged from the primary treated water flow pipe (4) connected to the aeration tank (1) by the operation of a pump (not shown), and is removed as a secondary treatment tank as an anaerobic tank. It is sent to the nitrogen reaction tank (2).

  The waste water (raw water) may contain organic substances and nitrous acid together with ammonia.

  Although not shown, a precipitation tank is installed between the aeration tank (1) and the denitrification reaction tank (2), and the primary treated water discharged from the aeration tank (1) is solidified in the precipitation tank. Liquid separation is preferred.

  In the denitrification reaction tank (2), sludge containing denitrification microorganisms cultured for a long time under the conditions of anaerobic ammonia oxidation is introduced. In this denitrification reaction tank (2), nitrous acid in the primary treated water And denitrification from the remainder of the ammonia. That is, in the denitrification reaction tank (2), wastewater containing ammonia nitrogen is removed by a denitrification microorganism using ammonia nitrogen as a hydrogen donor and nitrite nitrogen as a hydrogen acceptor in the presence of nitrite nitrogen. Biological denitrification is performed, and wastewater is purified by the following anammox (anaerobic ammonia oxidation) reaction.

anammox (anaerobic ammonia oxidation) reaction NH ₄ ⁺ + NO ₂ ⁻ → N ₂ ↑ + 2H ₂ O
In the denitrification reaction tank (2), the denitrification microorganisms are immobilized on the PVA gel carrier (8), and the PVA gel carrier (8) on which the denitrification microorganisms are immobilized flows upward in the denitrification reaction tank (2). A fluidized bed that circulates in

  The treated water purified in the denitrification reaction tank (2) is discharged from a discharge pipe (7) connected to the top of the denitrification reaction tank (2). Further, a part of the purified water is circulated and returned to the denitrification reaction tank (2) through the circulation pipe (5) by the operation of the circulation pump (6).

  In the present invention, the flow state of the PVA gel carrier (8) is locally increased by increasing the flow rate of the influent water in the circulating water inflow portion of the denitrification reaction tank (2), and the surface of the PVA gel carrier (8) It destroys the biofilm (microbe membrane) formed.

The flow rate of inflow water in the circulating water inflow part of the denitrification reaction tank (2) is 9500 to 20000 m / h. Here, if the flow rate of the influent water in the circulating water inflow part of the denitrification reaction tank (2) is less than 9500 m / h, the biofilm (microbe membrane) formed on the surface of the PVA gel carrier (8) is destroyed. This is not preferable because a biofilm (microorganism film) remains formed on the surface of the PVA gel carrier (8). In addition, if the flow rate of the influent water in the circulating water inflow part exceeds 20000 m / h, the pressure loss of the pump (6) becomes excessive, and a large amount of power for operation is required, which is not preferable.

  The fluidized bed in which the PVA gel carrier (8) on which the denitrifying microorganisms are fixed circulates in an upward flow in the denitrification reaction tank (2) is the influent water in the circulating water inflow portion of the denitrification reaction tank (2). By increasing the flow rate, the volume expands by 1 to 50%, preferably 1.5 to 40%, desirably 20 to 30%.

As shown in detail in FIG. 2, one end of the circulation pipe (5) is connected to the center of the bottom wall (2a) of the denitrification reactor (2), and the circulating water inflow part at the end of the circulation pipe (5) is connected to the denitrification reaction tank (2). A circulating water discharge nozzle (10) is provided so as to cover it. The circulating water discharge nozzle (10) includes a cylindrical peripheral wall (11) and a conical top wall (12) connected to the upper end of the cylindrical peripheral wall (11), and the cylindrical peripheral wall (11) of the circulating water discharge nozzle (10). a) one or radially viewed from the planar horizontal direction to the opening was a diameter 1 to 3 mm, preferably 1.5 to 2.5 mm, preferably 5 to 20 to about 2 mm, preferably 8-12 cyclic A water drain hole (13) is formed.

  The cylindrical peripheral wall (11) of the circulating water discharge nozzle (10) has a circular shape when viewed from the plane, and the top wall (12) of the circulating water discharge nozzle (10) has a conical shape. In addition, the cylindrical peripheral wall (11) of the circulating water discharge nozzle (10) may be elliptical when viewed from the plane, or has a polygonal square cylindrical shape when viewed from the plane. May be. The top wall (12) of the circulating water discharge nozzle (10) has a conical shape as shown in the figure, but the top wall (12) of the circulating water discharge nozzle (10) has a conical shape. It may be trapezoidal or substantially hemispherical, and may have a pyramid shape or a truncated pyramid shape.

  As described above, according to the method for treating ammonia-containing wastewater according to the present invention, raw water (drainage) containing ammonia nitrogen is treated in the presence of nitrite nitrogen, ammonia nitrogen as a hydrogen donor, and nitrite nitrogen as hydrogen. In the denitrification reaction tank (2) for biological denitrification by the denitrification microorganisms as the acceptor, by increasing the flow rate of the influent water in the circulating water inflow part of the denitrification reaction tank (2), the PVA gel carrier (8) Since the fluid state is locally increased to destroy the biofilm (microbe membrane) formed on the surface of the PVA gel carrier (8), according to the present invention, the bio to the surface of the PVA gel carrier (8) is obtained. The formation of a film can be suppressed, and not only the surface of the gel carrier (8) but also the inside of the gel carrier (8) enters and proliferates, so that the utilization efficiency of the PVA gel carrier (8) is improved. To raise Tree, may play a highly efficient nitrogen removal.

  In the water treatment method of the present invention, the fluidized bed in which the PVA gel carrier (8) on which the denitrifying microorganisms are fixed circulates in the upward flow in the denitrification reaction tank (2) is the circulating water in the denitrification reaction tank (2). Increasing the flow rate of the influent water in the inflow part and fluidizing the PVA gel carrier (8) so that it expands by 10 to 50%, preferably about 20 to 30% as the fluidization condition of the PVA gel carrier (8). Therefore, the pump power can be reduced and the denitrification reaction tank (2) can be made smaller compared to a fluidized bed in which the entire PVA gel carrier (8) is completely fluidized.

  In the invention of the water treatment apparatus for ammonia-containing waste water of the present invention, a circulating water discharge nozzle (10) is provided at the circulating water inflow portion of the denitrification reaction tank (2), and denitrification is performed from the circulating water discharge nozzle (10). A biofilm formed on the surface of the PVA gel carrier (8) by locally increasing the flow state of the PVA gel carrier (8) by increasing the flow rate of the influent water spilled into the reaction tank (2). (Microbial membrane) is destroyed.

The circulating water Ikidode cylindrical peripheral wall of the nozzle (10) (11), have opened the required number of circulating water Ikido Deana (13) is provided on or One horizontal direction radially viewed from the plane, the circulating water By making the squeezing direction of the horizontal direction a vortex in the fluidized bed, an effect of causing the PVA gel carrier (8) to flow violently is born, and thereby the biofilm on the surface of the PVA gel carrier (8) The formation of the PVA gel carrier (8) not only near the surface of the PVA gel carrier (8) but also inside the PVA gel carrier (8) and proliferate, thereby increasing the efficiency of use of the PVA gel carrier (8). It is possible to enhance the nitrogen removal efficiency.

  The cylindrical peripheral wall (11) of the circulating water discharge nozzle (10) has a circular or elliptical shape or a rectangular tube shape when viewed from the plane, and the top wall (12) of the nozzle (10) has a conical shape. , Frustoconical, or substantially hemispherical, pyramidal or truncated pyramidal, all of which have a so-called pointed shape, and circulate in the denitrification reactor (2). The PVA gel carrier (8) that has fallen on the top wall (12) of the water discharge nozzle (10) can rise smoothly, and the fluidization of the carrier is performed quickly, so that the PVA gel carrier (8) ) The formation of a biofilm on the surface can be suppressed, and not only the vicinity of the surface of the PVA gel carrier (8) but also the inside of the PVA gel carrier (8) enters and grows, whereby the PVA gel carrier Increase usage efficiency of (8) Bet is made, it can play a highly efficient nitrogen removal.

  In the present invention, the carrier (8) may be a granular carrier (8) having pores and a particle size of 0.2 to 10 mm. According to the granular carrier (8) having such pores, the denitrification reaction tank (2) with anammox bacteria is provided with an oxygen-free tank filled with the granular carrier (8), and the granular carrier ( 8) and fluidizing the circulating water inflow part of the denitrification reaction tank (2) to increase the flow rate of water at the circulating water inflow part of the denitrification reaction tank (2). ) Suppresses the formation of biofilms on the surface, and can efficiently propagate the bacterial cells not only in the vicinity of the surface of the granular carrier (8) but also in the pores, so that highly efficient nitrogen removal is there.

FIG. 4 is an enlarged horizontal sectional view of a main part of a denitrification reaction tank showing a second embodiment of the apparatus for carrying out the water treatment method for ammonia-containing waste water of the present invention, and FIG. 5 is a denitrification reaction tank of the water treatment apparatus. FIG.

Referring to the figure, in the water treatment apparatus for ammonia-containing waste water according to the present invention, the circulating water discharge nozzle (15) provided at the bottom of the denitrification reaction tank (2) is fed into the circulating water (5). A distribution main pipe (16) connected to the side end portion and four branch extraction pipes (17) connected orthogonally to the distribution main pipe (16) are seen from a plane. have been made with the comb, Ikido each branch Ikido extraction tube required number of circulating water which is open downward (17) Deana (18) is provided Te.

According to the second embodiment of the present invention, the circulating water introduced from one end of the circulation pipe (5) is opened downward to the four branch extraction pipes (17) of the circulation water extraction nozzle (15). By squeezing downward from the circulated water spill hole (18), a so-called turbulent flow is created, and the effect that the carrier (8) flows violently is produced, thereby forming a biofilm on the surface of the carrier (8). In addition to the vicinity of the surface of the carrier (8), the microbial cells enter the inside of the carrier (8), and the microbial cells proliferate, thereby increasing the utilization efficiency of the carrier (8). Thus, highly efficient nitrogen removal can be achieved. Further, since the circulating water discharge hole (18) is opened downward in each branch discharge pipe (17), the circulating water discharge hole (18) is not easily blocked by the carrier (8). .

  The circulating water discharge nozzle (15) shown in the figure has two relatively short two outside the four branch discharge pipes (17) connected orthogonally to the distribution main pipe (16). Seven circulating water discharge holes (18) opened downward in the branch extraction pipe (17a) and 11 openings opened downward in the two relatively long branch extraction pipes (17b) inside A circulating water outlet hole (18) is opened.

  The circulating water discharge nozzle (15) only needs to have at least two branch discharge pipes (17) connected orthogonally to the distribution main pipe (16), and each branch discharge pipe ( The number of circulating water outlet holes (18) opened downward in 17) is not limited to that shown in the figure. Furthermore, the opening direction of the circulating water discharge hole (18) opened downward in each branch discharge pipe (17) may not be directly below (hanging direction) but may be obliquely downward. In short, the opening direction of the circulating water discharge hole (18) is preferably left or right obliquely downward or right below in the range of 10 ° to 90 ° with respect to the horizontal direction. Thus, since the circulating water discharge hole (18) is opened downward in each branch extraction pipe (17), the circulating water discharge hole (18) is blocked by the carrier (8). There is no such thing.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
Experiments for carrying out the water treatment method according to the present invention were conducted using the apparatus shown in FIGS.

  In Example 1, as waste water (raw water) containing ammonia, experimental waste water (raw water) was prepared with ammonium chloride and sodium nitrite and used. In general, wastewater (raw water) containing ammonia is oxidized in the aeration tank (1) to nitrite a part of the ammonia in the raw water by a biological oxidation reaction by ammonia-oxidizing bacteria.

  Next, the experimental waste water was introduced into the denitrification reaction tank (2). A PVA gel carrier (8) in which anammox (anaerobic ammonia oxidation) is sufficiently conditioned after being cultured for a long time is put into the denitrification reaction tank (2). Denitrification is performed from the nitrous acid and the remainder of ammonia in the wastewater, and the wastewater is purified by an anammox (anaerobic ammonia oxidation) reaction. The purified treated water was discharged from the discharge pipe (7).

  In FIG. 2, simply introducing experimental wastewater into the denitrification reaction tank (2) has a low diffusion effect. Therefore, in order to promote mixing and stirring of nitrous acid and ammonia in the experimental wastewater, The mixing effect is increased by adjusting the amount of influent water. That is, a part of denitrified water purified in the denitrification reaction tank (2) is dehydrated from the top of the denitrification reaction tank (2) by the operation of the circulation pump (6) through the circulation pipe (5). Internally circulating to the bottom of (2), adjusting the internal volume of the anammox (anaerobic ammonia oxidation) reaction system in the denitrification reactor (2), and mixing and stirring nitrous acid and ammonia in the wastewater for experiments Accelerated so that the microbial reaction can take place quickly.

One end of the circulation pipe (5) is connected to the center of the bottom wall (2a) of the denitrification reaction tank (2), and the circulating water is discharged so as to cover the circulating water inflow part at the end of the circulation pipe (5). A nozzle (10) is provided. The circulating water discharge nozzle (10) includes a cylindrical peripheral wall (11) and a conical top wall (12) connected to the upper end of the cylindrical peripheral wall (11), and the cylindrical peripheral wall (11) of the circulating water discharge nozzle (10). ), the Ikido 10 of the circulating water of open diameter 2mm on whether one horizontal direction radially viewed from the plane Deana (13) is opened.

The influent water in the circulation water inflow to Ikidode from radial or One horizontal direction of the circulating water Ikido Deana (13) as viewed from the bored plane cylindrical wall (11) of the circulating water Ikidode nozzle (10) The flow rate was 9500 m / h.

The graph of FIG. 3 shows the relationship between the number of days that the wastewater treatment experiment according to Example 1 of the present invention has been performed for 60 days and the nitrogen removal rate (g / m ³ / d) in the wastewater for the experiment.

  As is apparent from the results of the graph of FIG. 3, according to the present invention, in the denitrification reaction tank (2), by increasing the flow rate of the inflow water in the circulating water inflow portion of the denitrification reaction tank (2), PVA Since the flow state of the gel carrier (8) is locally increased, a biofilm (microbe membrane) is not formed on the surface of the PVA gel carrier (8), not only near the surface of the PVA gel carrier (8). As the cells enter the PVA gel carrier (8) and continue to grow, the nitrogen removal rate in the waste water for experiments is steadily increasing, and the utilization efficiency of the PVA gel carrier (8) can be increased. It was found that high-efficiency nitrogen removal can be achieved and good purified water can be obtained.

Comparative Example 1
For comparison, an experiment was performed using the water treatment apparatus having the conventional denitrification reaction tank (20) shown in FIG. 6 and the other points as in Example 1 above.

  In the conventional water treatment apparatus, one end of the circulation pipe (21) is connected to the center of the bottom wall (20a) of the denitrification reaction tank (20), and a predetermined upper portion of the circulation pipe (21) above the circulating water inflow portion. A perforated plate (22) made of punching metal is horizontally stopped at the height. The perforated plate (22) has 80 circulating water discharge holes (23) having a diameter of 2 mm opened upward. In this denitrification reaction tank (20), denitrification microorganisms are fixed to the PVA gel carrier (24), and the circulating water introduced from one end of the circulation pipe (21) to the lower end of the denitrification reaction tank (20) is The PVA gel carrier (24) flows upward in the denitrification reaction tank (20) through the circulating water discharge hole (23) of the perforated plate (22) made of punching metal. A fluidized bed that circulates in

  And when the experimental waste water adjusted with the ammonium chloride and potassium nitrite used in the said Example 1 was introduce | transduced into the conventional denitrification reaction tank (20) and it experimented, the bottom part of a denitrification reaction tank (20) The flow rate of water discharged from the circulating water discharge hole (23) of the perforated plate (22) made of punching metal was 1300 m / h.

  The experimental results of Comparative Example 1 are also shown in the graph of FIG. As is apparent from the results of the graph of FIG. 3, in Comparative Example 1, a biofilm (microorganism film) is formed on the surface of the PVA gel carrier (24) in the denitrification reaction tank (20). (24) Since only the surface has become a place where the bacterial cells grow, it becomes difficult for the bacterial cells to enter the gel carrier (24), and the nitrogen removal rate in the waste water for experiments increases after 20 days. In addition, the utilization efficiency of the PVA gel carrier (24) could not be increased, and sufficient nitrogen removal could not be performed.

Example 2
Experiments for carrying out the water treatment method according to the present invention were conducted using the water treatment apparatus shown in FIGS.

  Wastewater having an ammonia concentration of 250 mg / L was supplied at 30 L / d to an aeration tank (1) as a primary treatment tank having a volume of 10 L. The aeration tank (1) was charged with a carrier conditioned with activated sludge derived from a sewage treatment plant, that is, a carrier made of polyurethane resin for holding aerobic microorganisms and ammonia oxidizing bacteria. At the bottom of the aeration tank (1), an aeration pipe (aeration means) for supplying air from the air supply pipe by the operation of an air pump is provided, and DO (dissolved oxygen amount) adjustment is provided at the top of the aeration tank (1). An apparatus (not shown) was provided and the amount of dissolved oxygen in the aeration tank (1) was adjusted to 1 mg / L.

  In this aeration tank (1), the organic matter in the raw water was decomposed by an oxidation reaction by an aerobic microorganism, and a part of the ammonia was oxidized by a biological oxidation reaction by an ammonia-oxidizing bacterium to nitrite. The effluent after the reaction from the aeration tank (1) was introduced into the denitrification reaction tank (2) of the same type as in Example 1 above in which 3 L of PVA gel carrier (8) conditioned under the anammox conditions was introduced. The waste water treatment was performed in the same manner as in Example 1.

  As a result, in the denitrification reaction tank (2), denitrification is performed from the nitrous acid and the remaining ammonia in the effluent after the reaction from the aeration tank (1), and the wastewater is purified by an anammox (anaerobic ammonia oxidation) reaction. However, the purified treated water did not contain any ammonia.

  On the other hand, the effluent after the reaction from the aeration tank (1) was introduced into the denitrification reaction tank (20) shown in Comparative Example 1, and the waste water treatment was performed in the same manner as in Comparative Example 1. However, ammonia remained in the treated water after the reaction in the denitrification reaction tank (20).

It is a flow sheet which shows 1st Embodiment of the water treatment apparatus of the ammonia containing waste_water | drain by this invention. It is a principal part expanded sectional view of the denitrification reaction tank of the water treatment apparatus. It is a graph showing the relationship between the experiment elapsed days of wastewater treatment, and the ammonia removal rate in wastewater. It is a principal part expanded horizontal sectional view of the denitrification reaction tank which shows 2nd Embodiment of the water treatment apparatus of the ammonia containing waste_water | drain by this invention. It is a principal part expanded vertical sectional view of the denitrification reaction tank of the water treatment apparatus. It is a principal part expanded sectional view of the denitrification reaction tank of the conventional water treatment apparatus.

1: Aeration tank (primary treatment tank)
2: Denitrification reaction tank (secondary treatment tank)
3: Raw water inflow pipe 4: Primary treated water flow pipe 5: Circulating pipe 6: Pump 7: Secondary treated water drain pipe 8: PVA gel carrier 10: Circulating water discharge nozzle 11: Cylindrical peripheral wall 12: Conical top walls 13: circulation water Ikido Deana 15: plane Yorimi circulating water comb Te Ikidode nozzle 16: distributing main pipe 17: branch Ikido extraction pipe 18: circulating water Ikido Deana

Claims (4)

A denitrification reactor that biologically denitrifies raw water (drainage) containing ammonia nitrogen in the presence of nitrite nitrogen, denitrifying microorganisms using ammonia nitrogen as a hydrogen donor and nitrite nitrogen as a hydrogen acceptor. with which, dehydration窒微organism is fixed in polyvinyl alcohol (PVA) gel carrier in the denitrification reactor, PVA gel carrier with a fixed denitrifying organisms, flow circulating in upflow denitrification reactor A method for water treatment of ammonia-containing wastewater forming a layer, wherein the flow rate of the influent water at the circulating water inflow portion of the denitrification reaction tank is 9500-20000 m / h, whereby the flow state of the PVA gel carrier is locally A method for water treatment of ammonia-containing wastewater, characterized by destroying a biofilm (microorganism membrane) formed on the surface of a PVA gel carrier . A denitrification reactor that biologically denitrifies raw water (drainage) containing ammonia nitrogen in the presence of nitrite nitrogen, denitrifying microorganisms using ammonia nitrogen as a hydrogen donor and nitrite nitrogen as a hydrogen acceptor. The denitrifying microorganisms are fixed to the PVA gel carrier in the denitrification reaction tank, and the PVA gel carrier to which the denitrification microorganisms are fixed forms a fluidized bed that circulates upward in the denitrification reaction tank. An ammonia-containing wastewater treatment device, wherein a circulating water discharge nozzle is provided at the circulating water inflow portion of the denitrification reaction tank, and the inflow water discharged from the circulation water discharge nozzle into the denitrification reaction tank. By setting the flow rate to 9500 to 20000 m / h, the flow state of the PVA gel carrier is locally increased, and the biofilm (microorganism film) formed on the surface of the PVA gel carrier is destroyed. Water treatment of wastewater containing ammonia Location. The circulating water discharge nozzle provided at the bottom of the denitrification reaction tank has a cylindrical peripheral wall and a top wall connected to the upper end of the cylindrical peripheral wall. The water treatment apparatus according to claim 2, further comprising a required number of circulating water discharge holes opened horizontally. A circulating water discharge nozzle provided at the bottom of the denitrification reaction tank has a distribution main pipe connected to the circulating water inflow end of the circulation pipe, and a branch pipe connected to the distribution main pipe in a comb shape when viewed from the plane. The water treatment device according to claim 2, wherein a required number of circulating water discharge holes that are open downward are provided in each branch discharge pipe.

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