JP2006035028A - Bio-deodorization method, bio-deodorization system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bio-deodorization system capable of preventing leak of malodor and lowering of deodorization performance with time, with superior cost performance. <P>SOLUTION: This bio-deodorization system 10 is provided with a bio-deodorization apparatus 11 of a circulating water spray type, a denitrification apparatus 12, an organic matter supply apparatus 13, and a control device 14. The control device 14 controls a pump 49 to adjust an amount of the organic matter O supplied from the organic matter supply apparatus 13, and to keep concentration of nitrate nitrogen and nitrite nitrogen contained in circulation water W2 less than 2,500 ppm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a biological deodorizing method and a biological deodorizing system in which ammonia is converted into nitric acid or the like by a microorganism having a nitrifying action and deodorized.

  Conventionally, equipped with a biological deodorizing device that biologically deodorizes malodorous gases (eg, ammonia gas) generated in composting plants for organic waste, sewage treatment plants, barns, food processing plants, etc. using microorganisms. Biological deodorization systems are well known. In general, a biological deodorization apparatus in this type of biological deodorization system includes a container into which ammonia gas is introduced, and the container is filled with a filling carrier carrying deodorizing microorganisms. The ammonia gas introduced into the container is deodorized by the action of deodorizing microorganisms (nitrification action) when passing through the packed carrier, and is then discharged out of the container through the exhaust duct. In addition, a sprinkler is disposed on the top of the filling carrier, and the activity of the deodorizing microorganisms is maintained by sprinkling water from the sprinkler to the filling carrier.

  Such a biological deodorization apparatus includes a non-circulating watering method in which water is thrown away and a circulating watering method in which water collected in the container is collected without being discarded and reused as water for watering. However, since the former non-circulating watering method has disadvantages in terms of cost and environment, the latter circulation watering method is currently considered to be preferable. However, when the circulating watering method is adopted, nitric acid and nitrous acid generated from ammonia by the nitrification action of microorganisms accumulate in the water for watering, so that the concentration gradually increases when used as it is. And when the water for spraying containing such high concentration nitric acid and nitrous acid is sprinkled, the activity of the deodorizing microorganisms decreases, and the deodorizing performance cannot be maintained over a long period of time.

Therefore, as a circulating watering-type biological deodorization device that can eliminate the above drawbacks, for example, a technique of replenishing and diluting fresh water according to the ion concentration of watering water, and performing watering by lowering the ion concentration of watering water to an appropriate concentration Has been proposed (see, for example, Patent Document 1).
JP 2000-42353 A (FIG. 1 etc.)

  However, in the case of the above prior art, it is necessary to replenish a large amount of new water in order to reduce the ion concentration of water for spraying to an appropriate concentration, and accordingly, a large amount of waste water is generated during operation of the biological deodorization apparatus. Therefore, there is a problem that the wastewater treatment cost and the water cost are increased, and the running cost becomes high. In addition, a large-scale waste water treatment facility is required separately, and there is a problem that the facility cost increases.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is a biological deodorization method and a biological deodorization system that can prevent malodor leakage and deodorization performance over time, and are excellent in cost. Is to provide.

  In order to solve the above-mentioned problems, the invention described in claim 1 is directed to a biological deodorizing apparatus of a circulating sprinkling operation system in which ammonia is converted into nitric acid and / or nitrous acid by a microorganism having a nitrification action, and the biological deodorizing apparatus. And a denitrification device that converts nitric acid and / or nitrous acid to nitrogen by a microorganism having a denitrification action, and supplies organic substances that serve as nutrients for the microorganism having the denitrification action. In a biological deodorization method using a biological deodorization system comprising an organic substance supply device and configured to circulate circulating water between the biological deodorization device and the denitrification device, nitrate nitrogen contained in the circulating water And a biological deodorizing method characterized in that control is performed to maintain the concentration of nitrous nitrogen at a value of 2500 ppm or less.

According to the invention described in claim 1, nitrate nitrogen and / or nitrous acid is changed to nitrogen by a microorganism having a denitrification action in the denitrification apparatus, and by controlling the nitrate nitrogen contained in the circulating water and The concentration of nitrite nitrogen is maintained at a value of 2500 ppm or less. As a result, the activity of the microorganisms in the biological deodorization device is maintained, and the deterioration of the deodorization performance with time is prevented. In addition, according to the present invention, it is possible to realize a closed system that does not require the circulation water to be discarded, and it is not necessary to supply a large amount of new water as in the prior art. Therefore, compared to the prior art, water costs are not required, and waste water treatment costs are not required. Therefore, running costs can be kept low. In addition, since a large wastewater treatment facility is not required separately, the facility cost can be kept low.
Here, “nitrate nitrogen and nitrite nitrogen contained in circulating water” means nitrate nitrogen and nitrite nitrogen (that is, nitrate ion and nitrite ion) normally contained as ions in the circulating water. means. The reason why the concentration of nitrate nitrogen and nitrite nitrogen is maintained at a value of 2500 ppm or less in the present invention is to maintain the activity of microorganisms in the biological deodorization apparatus. The concentration is preferably maintained at a value of 0 ppm to 1500 ppm, more preferably a value of 100 ppm to 1000 ppm, and most preferably a value of 300 ppm to 700 ppm.

  In the present invention, for example, nitrifying bacteria such as Nitrosomonas and Nitrosococcus are used as microorganisms having a nitrifying action, and denitrifying bacteria such as Alcaligenes and denitrificans are used as microorganisms having a denitrifying action.

  The invention according to claim 2 is the invention according to claim 1, wherein the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water is 2500 ppm or less by adjusting the amount of organic matter supplied from the organic matter supply device. The main point is to perform control to maintain the value of.

  According to the second aspect of the present invention, the concentration control of nitrate nitrogen and nitrite nitrogen can be performed by a relatively simple method such as adjustment of the amount of organic matter supplied from the organic matter supply device. The organic substance used here is not particularly limited as long as it can serve as a nutrient for microorganisms having a denitrifying action. For example, alcohols such as ethanol and methanol, sugars such as glucose, and organic acids such as citric acid are used. Is possible.

  The invention according to claim 3 is the biochemical oxygen demand of the circulating water discharged from the denitrification device by adjusting the amount of organic matter supplied from the organic matter supply device in claim 1 or 2. The gist is to perform control to maintain the amount at a value of 100 ppm or less.

  According to the invention described in claim 3, the biochemical oxygen demand of the circulating water can be controlled by a relatively simple method such as adjustment of the amount of organic matter supplied from the organic matter supply device. Moreover, by performing such control, it is possible to prevent excessive supply of organic matter to the denitrification apparatus. As a result, it is difficult for organic substances to flow from the denitrification device to the biological deodorization device, and the problem that the nitrification action is reduced by adversely affecting microorganisms in the biological deodorization device is also avoided. In addition, since a necessary amount of organic matter can be supplied, consumption of the organic matter can be reduced, and the running cost of the system can be suppressed.

  According to a fourth aspect of the present invention, the denitrification apparatus according to any one of the first to third aspects includes a carrier for supporting the microorganism having the denitrification action, and the carrier. The gist of the present invention is that it is a particulate material in which a bone component or calcium phosphate is contained in a ceramic porous body.

  According to the invention described in claim 4, the bone component or calcium phosphate contained in the carrier has a high affinity with microorganisms having a denitrifying action, and therefore has an excellent ability to activate the microorganisms. Contributes to the reduction of nitrite nitrogen. Further, since the ability of activating microorganisms is high in the denitrification apparatus, it is possible to reduce the filling amount of the carrier for supporting the microorganisms, and downsizing of the denitrification apparatus can be realized. The ceramic porous body used in the present invention is effective in improving the denitrification effect when at least one of silica and alumina is used as a main component. Further, as bone components, bone components such as cattle, horses, sheep, chickens, and fish, and bone phosphates and bone phosphate can be used. Bone phosphate is obtained by dissolving bovine bone with an acid, neutralizing with calcium hydroxide, and filtering, and is also used as a fertilizer.

  The invention according to claim 5 is provided separately from the biological deodorization apparatus of the circulating sprinkling operation method in which ammonia is converted to nitric acid and / or nitrous acid by a microorganism having a nitrification action and deodorized, and the biological deodorization apparatus, A denitrification device that converts nitric acid and / or nitrous acid into nitrogen by a microorganism having a denitrification effect, and an organic substance supply device that supplies organic matter as nutrients for the microorganism having the denitrification effect to the denitrification device, In a biological deodorization system configured so that circulating water circulates between a biological deodorization device and the denitrification device, supply amount adjusting means for adjusting the amount of organic matter supplied from the organic matter supply device, and the circulating water The concentration of nitrate nitrogen and nitrite nitrogen contained in the water is maintained at a value of 2500 ppm or less, and the biochemical oxygen demand of the circulating water discharged from the denitrification apparatus is 100 p. m to maintain the following values, the biological deodorization system characterized in that a control means for controlling the supply amount adjusting means and the gist thereof.

  According to the fifth aspect of the present invention, the amount of the organic substance supplied from the organic substance supply device is automatically adjusted without manual operation by the control means controlling the supply amount adjusting means. By adjusting the supply amount of this organic matter, the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water is maintained at a value of 2500 ppm or less, and the biochemical oxygen demand of the circulating water is 100 ppm or less. Maintained at the value. As a result, the activity of the microorganisms in the biological deodorization device is maintained, and the deterioration of the deodorization performance with time is prevented. In addition, according to the present invention, it is possible to realize a closed system that does not require the circulation water to be discarded, and it is not necessary to supply a large amount of new water as in the prior art. Therefore, in addition to not costing water as compared with the prior art, wastewater treatment costs are also reduced. As a result, the running cost can be kept low. In addition, since a large wastewater treatment facility is not required separately, the facility cost can be kept low.

  As described above in detail, according to the inventions described in claims 1 to 4, it is possible to prevent a malodorous leak and a degrading performance over time, and to provide a biological deodorizing method excellent in cost. Can do. In addition, according to the invention described in claim 5, it is possible to provide a biological deodorization system that can prevent a foul odor leakage and a decrease in the deodorization performance with time, and is excellent in cost.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment embodying the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, the biological deodorization system 10 of the present embodiment is a system for deodorizing odorous gas discharged from an organic waste composting plant, that is, odorous gas containing a lot of ammonia gas, A biological deodorization device 11, a denitrification device 12, an organic substance supply device 13, and a control device 14 are provided.

  The biological deodorization device 11 is a device that deodorizes by converting ammonia into nitric acid and / or nitrous acid by microorganisms having a nitrifying action, and the denitrification apparatus 12 converts nitric acid and / or nitrous acid to nitrogen by microorganisms having a denitrifying action. It is a device to change to. Moreover, the organic substance supply device 13 is an apparatus that supplies the organic matter that serves as nutrients for microorganisms having a denitrifying action to the denitrification device 12, and the control device 14 is configured to supply organic matter that is supplied from the organic matter supply device 13 to the denitrification device 12. It is a device for adjusting the amount.

  The biological deodorization apparatus 11 includes a deodorizing tank 15 having a vertically long cylindrical shape, and a carrier holding part 17 is formed at a substantially central portion in the deodorizing tank 15. The carrier holding part 17 is filled with a filling carrier 18 carrying nitrifying bacteria which are deodorizing microorganisms. In this embodiment, an aggregate of ceramic porous body particles having a large number of pores is used as the filling carrier 18. The average particle size of the particles of the ceramic porous body can be set to about 1 mm to 100 mm, and is set to about 1 mm to 5 mm here. Since the ceramic porous body has a large surface area, it contributes to the adsorption of ammonia and the propagation and activation of microorganisms.

  In addition, a gas introduction chamber 19 is provided immediately below the carrier holding portion 17 in the biological deodorization apparatus 11, and a gas introduction duct 20 leading to a composting plant (not shown) is connected to the gas introduction chamber 19. A fan 21 for pressure-feeding ammonia gas G1 generated by the composting plant to the gas introduction chamber 19 of the deodorization tank 15 is disposed in the middle of the gas introduction duct 20. Below the gas introduction chamber 19, a water storage tank 22 is provided in which the sprinkled water is stored. On the other hand, an upper region of the carrier holding portion 17 is a watering chamber 23, and a plurality of watering nozzles (not shown) for watering the filling carrier 18 are installed in the watering chamber 23. An exhaust duct 25 is connected to the watering chamber 23, and the deodorized gas G <b> 2 is discharged to the outside through the exhaust duct 25.

  The biological deodorization apparatus 11 includes a sprinkling pipe 31 outside the deodorization tank 15. The start end (lower end) of the water sprinkling pipe 31 is connected to the water storage tank 22, while the terminal end (upper end) of the water sprinkling pipe 31 is connected to the water spray chamber 23 of the deodorizing tank 15. A plurality of watering nozzles are attached to the end of such watering pipe 31. In the middle of the sprinkling pipe 31, a pump 32 is provided for pumping the sprinkling water W <b> 1 in the sprinkling pipe 31 from the start end side to the end side. Therefore, when the pump 32 is operated, the water W in the water storage tank 22 is collected as the water sprinkling water W1, and the water sprinkling water W1 is sprinkled from each watering nozzle toward the filling carrier 18. That is, the biological deodorization apparatus 11 of the present embodiment collects the water W accumulated in the deodorization tank 15 without discarding it, and circulates and supplies it through the sprinkling pipe 31, thereby reusing it as the sprinkling water W1. Is adopted.

  The basic operation of the biological deodorization apparatus 11 of the circulating sprinkling operation system configured as described above will be described.

The malodorous gas G1 introduced into the gas introduction chamber 19 through the gas introduction duct 20 advances in the deodorizing tank 15 upward. Since the nitrifying bacteria are propagated on the packed carrier 18, when the malodorous gas G1 passes through the packed carrier 18, the odorous component ammonia is oxidized and decomposed and is not brominated. The deodorized gas G2 that has not been brominated is passed through the water sprinkling chamber 23 and discharged to the outside from the exhaust duct 25. That is, in this biological deodorization apparatus 11, ammonia which is an odor component contained in the malodorous gas G1 is in the water sprinkled as nitrate ions (NO ³⁻ ) or nitrite ions (NO ²⁻ ) by nitrifying bacteria. Or dissolved in sprinkled water. Thus, the water containing nitrate ions, nitrite ions, etc. falls from the filling carrier 18 and is stored in the water storage tank 22. Therefore, the water W in the water storage tank 22 contains nitrate ions and the like. The water W in the water storage tank 22 contains, for example, ammonium ions (NH ⁴⁺ ) and ammonia in addition to nitrate ions and nitrite ions.

  When the pump 32 is operated, the water W in the water storage tank 22 is collected as the water for spraying W1 and reaches the watering nozzles through the watering pipes 31. And the water W1 for watering sprinkled from each watering nozzle falls and falls on the filling carrier 18. As a result, the activity of nitrifying bacteria is maintained. Watering to the filling carrier 18 is performed at predetermined intervals, for example, every 1 to 5 hours.

  By the way, when the water W1 containing high-concentration nitrate ions or the like is sprinkled on the filling carrier 18, the activity of the deodorizing microorganisms on the filling carrier 18 is lowered, and the deodorizing ability is not maintained. Therefore, denitrification (reduction of nitric acid or nitrous acid to nitrogen gas) is performed using the denitrification apparatus 12, and nitrate ions and nitrite ions (that is, nitrate nitrogen and nitrite nitrogen) contained in the water W1 for watering. ) Is suppressed.

  Next, the structure of the denitrification apparatus 12 which is incidental equipment provided separately from the biological deodorization apparatus 11 will be described.

  The denitrification apparatus 12 includes a denitrification tank 41 having a vertically long cylindrical shape, and a carrier holding portion 42 is formed at the approximate center of the denitrification tank 41. The carrier holding part 42 is filled with a filling carrier 43 that carries denitrifying bacteria as microorganisms. In the present embodiment, an aggregate of a granular material in which a bone component or calcium phosphate is contained in a ceramic porous body having a large number of pores is used as a filling carrier.

  Specifically, waste molding sand discharged from a foundry, bone phosphate powder, and water are appropriately blended, and a molded material is molded by pressurizing a mixed material obtained by mixing them. And the aggregate | assembly of the particle | grains of the porous sintered compact made porous by baking the molded object is used as the filling support | carrier 43. FIG. The average particle size of the particles of the porous sintered body can be set to about 0.5 mm to 30 mm, and is set to 1 mm to 10 mm which is a more preferable range here. The waste foundry sand as a raw material contains silica and alumina as main components, and also includes substances such as magnesia, iron oxide and carbonaceous powder particles. When heat treatment is performed, organic substances contained in the waste casting sand disappear, and the disappearance traces become pores. When pores are formed in this way, the surface area is increased by becoming a porous body, contributing to the propagation and activation of microorganisms. Bone phosphate has calcium phosphate as a main component and has high affinity with microorganisms, so that the microorganisms can be activated and contribute to the reduction of nitrate nitrogen and nitrite nitrogen using the microorganisms.

  The denitrification tank 41 of the denitrification apparatus 12 is connected to the water storage tank 22 of the biological deodorization apparatus 11 via pipes 45 and 46, and the water W stored in the water storage tank 22 is used as the circulating water W2 and the water storage tank. It is comprised so that it may circulate between tanks 22. Specifically, the starting end (lower end) of the pipe 45 is connected to the water storage tank 22, while the terminal end (upper end) of the pipe 45 is connected to the upper part of the denitrification tank 41. A pump 47 is provided in the middle of the pipe 45 to pump the water in the pipe 45 from the start end side to the end side. Therefore, when the pump 47 is operated, the water W in the water storage tank 22 is sucked up and supplied to the denitrification tank 41. The circulating water W2 is filtered through the packed carrier 43. At that time, nitrate nitrogen and nitrite nitrogen contained in the circulating water W2 are denitrified by the action of microorganisms in the packed carrier 43 and reduced to nitrogen gas. Is done.

  The starting end of the pipe 46 is connected to the lower part of the denitrification tank 41, and the end of the pipe 46 is connected to the water storage tank 22, and the circulating water W <b> 2 denitrified in the denitrification tank 41 is passed through the pipe 46. The water tank 22 is returned.

  Furthermore, the organic matter supply device 13 is connected to the denitrification device 12 via an organic matter supply pipe 48. A pump 49 is provided in the middle of the pipe 48, and the organic substance O is supplied from the organic substance supply apparatus 13 to the denitrification apparatus 12 by operating the pump 49. In the denitrification apparatus 12, when the organic substance O that serves as nutrients for the denitrifying bacteria is supplied, the denitrifying bacteria are activated and the denitrifying ability is maintained. In the present embodiment, methanol is used as the organic substance O supplied by the organic substance supply device 13.

  The control device 14 is configured around a known computer including a CPU, a ROM, a RAM, an input / output port, and the like. The control device 14 controls the pump 49 based on the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water W2 and the biochemical oxygen demand (BOD), thereby removing the organic substance supply device 13. The amount of organic matter supplied to the nitrogenation device 12 is adjusted.

  The water storage tank 22 is provided with a sensor (specifically, a known sensor for measuring electrical conductivity) 50 for measuring the concentrations of nitrate ions and nitrite ions contained in the circulating water W2. The control device 14 takes in the detection signal of the sensor 50 and calculates the concentrations of nitrate nitrogen and nitrite nitrogen based on the detection signal. Further, a known sensor 51 for measuring a chemical oxygen demand (COD) is provided in the vicinity of the outlet of the denitrification apparatus 12, that is, in the vicinity of the start end of the pipe 46. The control device 14 takes in the detection signal of the sensor 51 and obtains the COD based on the detection signal. The control device 14 stores in advance table data for conversion from COD to BOD value, and the control device 14 calculates the BOD value using the table data.

The control device 14 controls the drive of the pump 49 so that the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water W2 is 2500 ppm or less, and adjusts the amount of organic matter to be supplied. Moreover, the control apparatus 14 controls the drive of the pump 49 so that BOD of the circulating water W2 becomes a value of 100 ppm or less, and adjusts the quantity of the organic substance to supply. In addition, as a specific mode for controlling the driving of the pump 49, a control for increasing or decreasing the time for driving the pump 49 can be exemplified.
[Example 1]

  Next, Example 1 that further embodies the above embodiment will be described.

In the biological deodorization apparatus 11, 12 liters of ceramic porous body particles were filled in the carrier holding unit 17 of the deodorization tank 15. And the ammonia gas concentration (namely, inlet ammonia concentration) in the gas introduction duct 20 was set to 40 ppm, and the biological deodorizing apparatus 11 was operated. In this case, the LV value (empty linear velocity) was set to 0.06 m / s, and the SV value (space velocity) was set to 600 h ⁻¹ .

  On the other hand, in the denitrification apparatus 12, the ceramic porous body is made porous by firing a mixed material of waste foundry sand (80% by volume) and bone phosphoric acid (20% by volume) discharged from the foundry. One liter of the particles was filled in the carrier holding part 42 of the denitrification tank 41. In addition, Alcaligens family denitrifying bacteria extracted from the soil were supported on the packing carrier 43. Specifically, a loading method was used in which a carrier was introduced into a liquid obtained by shaking and denitrifying bacteria at 25 ° C. overnight using a liquid medium, and left for 2 hours before being used. And the filtration speed | rate was set to 5 m / d and the denitrification apparatus 12 was drive | operated. The organic substance supply device 13 was filled with a 10% methanol solution as the organic substance O, and a predetermined amount of the organic substance O was supplied to the denitrification apparatus 12 every day.

  Then, after a predetermined number of days have passed, the concentration of nitrate nitrogen and nitrite nitrogen in the water tank 22 and the concentration of ammonia gas contained in the deodorized gas G2 passing through the exhaust duct 25 (ie, the outlet ammonia concentration) The biochemical oxygen demand (that is, outlet BOD concentration) contained in the circulating water W2 discharged from the denitrification apparatus 12 was measured.

The results are shown in the table of FIG. 2 and the graphs of FIGS. As shown in FIGS. 2 and 3, in the first embodiment, the concentration of nitrate nitrogen and nitrite nitrogen in the water tank 22 is maintained at a substantially constant value (340 ppm to 680 ppm) centering on 500 ppm. I was able to. Further, as shown in FIGS. 2 and 4, the outlet ammonia concentration was 1 ppm or less, and a stable deodorizing ability could be obtained. That is, by suppressing the increase in the concentration of nitrate nitrogen and nitrite nitrogen, volatilization of ammonia was prevented and nitrifying bacteria were activated, thereby preventing leakage of ammonia gas. Further, as shown in FIG. 2 and FIG. 5, the BOD concentration at the outlet of the denitrification device 12 is also maintained at a value of 100 ppm or less, and an organic substance is supplied in a necessary amount so as not to flow into the biological deodorization device 11. It was confirmed.
[Comparative Example 1]

In Comparative Example 1, the organic substance was continuously supplied (excess supply) without adjusting the supply amount of the organic substance to the denitrification apparatus 12 (that is, without performing any control by the control apparatus 14). The other conditions were the same as in Example 1. In Comparative Example 1, since a large amount of organic matter was supplied to the denitrification apparatus 12, the BOD concentration increased rapidly (see FIG. 4). In other words, the organic matter is not decomposed in the denitrification apparatus 12 and flows into the biological deodorization apparatus 11 side, which adversely affects nitrifying bacteria and the deodorization ability is reduced. Moreover, the denitrification in the denitrification apparatus 12 abruptly occurred, the pH in the water storage tank 22 was increased, the ammonia was volatilized rapidly, and the outlet ammonia concentration was increased (see FIG. 5). From this, it was confirmed that it was necessary to maintain the BOD concentration at the outlet of the denitrification apparatus 12 at a value of 100 ppm or less. In the measurement of Comparative Example 1, since the deodorization could not be performed in the biological deodorization apparatus 11, the system operation was stopped halfway (25th day).
[Comparative Example 2]

  In Comparative Example 2, the denitrification apparatus 12 was not filled with the filling carrier 43, and denitrification was not performed. The operating state of the biological deodorizing apparatus 11 was the same as that in Example 1. As shown in FIGS. 3 and 4, in Comparative Example 2, the concentration of nitrate nitrogen and nitrite nitrogen is 2500 ppm in a predetermined period (in this example, a period of 60 days from the start) after the start of measurement. The deodorizing ability of the biological deodorizing apparatus 11 was stable because the outlet ammonia concentration was 1 ppm or less. However, it can be seen that the concentration of nitrate nitrogen and nitrite nitrogen increases and exceeds 2500 ppm after a predetermined period of time, and therefore the outlet ammonia concentration exceeds 1 ppm due to a decrease in the deodorizing ability of the biological deodorization apparatus 11. I understand. From this, in order to maintain the deodorizing ability of the biological deodorizing apparatus 11, it was confirmed that the concentration of nitrate nitrogen and nitrite nitrogen contained in the water W of the water storage tank 22 must be maintained at 2500 ppm or less. .

  Now, according to the embodiment described in detail above, the following effects can be obtained.

  (1) Since the denitrification of the circulating water W2 is performed in the denitrification apparatus 12, the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water W2 is maintained at a value of 2500 ppm or less. As a result, the activity of the nitrifying bacteria in the biological deodorizing device 11 is maintained, so that the deodorizing performance is prevented from decreasing over time, and the amount of ammonia volatilized during watering is reduced, so that bad odor leaks outside the deodorizing tank 15. Is prevented.

  (2) The biological deodorization system 10 of the present embodiment has a closed system configuration that does not require the circulating water W2 to be discarded, and a large amount of new water as in the case of the prior art is not required. Therefore, compared to the prior art, water costs are not required, and waste water treatment costs are not required. Therefore, running costs can be kept low. In addition, since a large wastewater treatment facility is not required separately, the facility cost can be kept low. Moreover, since it is not necessary to provide a wastewater treatment facility, the degree of freedom when installing the biological deodorizing system 10 is increased.

  (3) When the control device 14 controls the driving of the pump 49, the amount of the organic matter O supplied from the organic matter supply device 13 is automatically adjusted without manual operation, and the organic matter O is excessive in the denitrification device 12. It is prevented from being supplied. For this reason, the biochemical oxygen demand (BOD) contained in the circulating water W2 is maintained at a value of 100 ppm or less. As a result, it is possible to avoid the problem that the organic substance O flows into the biological deodorization apparatus 11, adversely affects the microorganisms in the biological deodorization apparatus 11, and the nitrification action by the microorganisms is reduced. Further, since the organic substance O can be supplied in a necessary amount, the consumption amount of the organic substance O is reduced, and the running cost can be suppressed.

  (4) Since bone phosphate contained in the filling carrier 43 of the denitrification apparatus 12 has high affinity with microorganisms having a denitrification action, the microorganisms can be activated, and nitrate nitrogen and nitrite nitrogen Can contribute to the reduction of Moreover, since the denitrification apparatus 12 has a high ability to activate microorganisms, the packed carrier 43 can be made small, and the denitrification apparatus 12 as ancillary equipment can be downsized, and the entire system can be made large. Can be avoided.

  (5) Since the waste foundry sand discarded from the foundry is effectively used as the raw material for the filling carrier 43, the cost of the filling carrier 43 can be reduced.

  The embodiment of the present invention may be modified as follows.

  In the above embodiment, the pump 49 is used as the supply amount adjusting means, but the present invention is not limited to this. For example, an electromagnetic valve may be provided in the middle of the pipe 48 and the supply amount of the organic substance O may be adjusted by opening / closing the electromagnetic valve.

  In the above embodiment, the BOD value is maintained at 100 ppm by adjusting the amount of the organic substance O supplied from the organic substance supply device 13, but the present invention is not limited to this. For example, a BOD reduction device (specifically, a reduction device that lowers the BOD value by sending oxygen into the circulating water W2 and bubbling) may be provided in the middle of the pipe 46. However, in this configuration, excess organic matter O is supplied to the denitrification apparatus 12, and therefore, the configuration in which the supply amount of the organic matter O is adjusted as in the above embodiment reduces the consumption cost of the organic matter O. It can be suppressed and is preferable in practical use.

  -As in Example 1 above, if the concentration of nitrate nitrogen and nitrite nitrogen in the water storage tank 22 can be maintained at a substantially constant value centered on 500 ppm, the value of BOD must be 100 ppm or less. It becomes. In this case, it is not necessary to monitor the BOD value, and the sensor 51 can be omitted.

  In the above embodiment, the sensor 50 for detecting the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water W2 is provided in the water tank 22, but is not limited to this. For example, it may be provided in the middle of the pipe 45.

  The control device 14 controls the drive of the pump 49 and adjusts the supply amount of the organic substance O. In addition to the pump 49, the entire system such as the pumps 32 and 47 and the fan drive 21 is integrated. You may comprise so that it may control.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below.

  (1) The electrical conductivity of the circulating water is detected by a sensor, and the concentration of nitrate nitrogen and nitrite nitrogen calculated based on the electrical conductivity is maintained at a value of 2500 ppm or less. The biological deodorization method according to 2.

  (2) The chemical oxygen demand of circulating water discharged from the denitrification device is detected by a sensor, and the biochemical oxygen demand calculated based on the chemical oxygen demand is maintained at a value of 100 ppm or less. The biological deodorizing method according to claim 3.

  (3) The biological deodorization method according to claim 4, wherein the ceramic porous body contains at least one of silica and alumina as a main component.

Schematic which shows the biological deodorizing system of embodiment which actualized this invention. The table | surface which shows the measurement result in Example 1 and Comparative Examples 1 and 2. FIG. The graph which shows the change of nitrate nitrogen and nitrite nitrogen concentration in Example 1 and Comparative Examples 1 and 2. The graph which shows the change of the ammonia concentration in Example 1 and Comparative Examples 1 and 2. FIG. The graph which shows the change of the BOD density | concentration in Example 1 and Comparative Examples 1 and 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Biological deodorizing system 11 ... Biological deodorizing apparatus 12 ... Denitrification apparatus 13 ... Organic substance supply apparatus 14 ... Control apparatus as control means 43 ... Filling carrier 49 ... Pump as supply amount adjustment means O ... Organic substance W2 ... Circulating water

Claims (5)

A biological deodorizing apparatus of a circulating sprinkling operation system that deodorizes by converting ammonia into nitric acid and / or nitrous acid by microorganisms having a nitrifying action, and the biological deodorizing apparatus are provided separately from each other. And / or a denitrification device that converts nitrous acid into nitrogen, and an organic substance supply device that supplies the organic matter serving as nutrients for the microorganisms having the denitrification action to the denitrification device, the biological deodorization device and the denitrification device, In a biological deodorization method using a biological deodorization system configured to circulate circulating water between
A biological deodorization method comprising controlling the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water to a value of 2500 ppm or less.   The control of maintaining the concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water at a value of 2500 ppm or less by adjusting the amount of organic matter supplied from the organic matter supply device. Item 2. The biological deodorization method according to Item 1.   By controlling the amount of organic matter supplied from the organic matter supply device, control is performed to maintain the biochemical oxygen demand of the circulating water discharged from the denitrification device at a value of 100 ppm or less. The biological deodorizing method according to claim 1 or 2.   The denitrification apparatus includes a carrier for supporting the microorganism having the denitrification action, and the carrier is a particulate material in which a ceramic porous body contains bone components or calcium phosphate. The biological deodorization method according to any one of claims 1 to 3, wherein the biological deodorization method is provided. A biological deodorizing apparatus of a circulating sprinkling operation system that deodorizes by converting ammonia into nitric acid and / or nitrous acid by microorganisms having a nitrifying action, and the biological deodorizing apparatus are provided separately from each other. And / or a denitrification device that converts nitrous acid into nitrogen, and an organic substance supply device that supplies the organic matter serving as nutrients for the microorganisms having the denitrification action to the denitrification device, the biological deodorization device and the denitrification device, In the biological deodorization system configured to circulate the circulating water between
A supply amount adjusting means for adjusting the amount of organic matter supplied from the organic matter supply device;
The concentration of nitrate nitrogen and nitrite nitrogen contained in the circulating water is maintained at a value of 2500 ppm or less, and the biochemical oxygen demand of the circulating water discharged from the denitrification device is a value of 100 ppm or less. A biological deodorizing system comprising control means for controlling the supply amount adjusting means.

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