JP4507173B2 - Nitrite-type nitrification method and apparatus, and wastewater treatment apparatus - Google Patents

Description

  The present invention relates to a nitrite-type nitrification treatment method and apparatus and a wastewater treatment apparatus, and more particularly to a nitrification technique using a nitrite-type nitrification carrier that preferentially accumulates ammonia-oxidizing bacteria that nitrify ammonia to nitrite.

  In the conventional nitrification treatment method, ammonia in ammonia wastewater is nitrified (oxidized) to nitrite by ammonia-oxidizing bacteria, a kind of nitrifying bacteria, and nitrite is converted to nitric acid by nitrite-oxidizing bacteria, which is a kind of nitrifying bacteria. Until nitrification. The nitrogen component is removed from the ammoniacal wastewater by reducing the nitric acid produced by nitrification to nitrogen gas by denitrification.

  Thus, the conventional nitrification method nitrifies ammonia to nitric acid via nitrous acid, but if nitrite type nitrification treatment that stops the nitrification reaction at the nitrous acid stage can be performed, nitrous acid In addition to reducing the amount of oxygen supplied when converting from nitric acid to nitric acid, the amount of hydrogen donor (eg, methanol) used is reduced by reducing nitrous acid to nitrogen gas rather than reducing nitric acid to nitrogen gas in the denitrification process. it can. However, since nitrite-oxidizing bacteria have a faster growth rate than ammonia-oxidizing bacteria, nitrite-type nitrification treatment has been difficult.

  Against this background, the present applicant inactivates the nitrite-oxidizing bacteria by heat-treating at least a microorganism group (for example, activated sludge) in which ammonia-oxidizing bacteria and nitrite-oxidizing bacteria survive. The present inventors have invented a nitrite type nitrification carrier in which ammonia-oxidizing bacteria are preferentially accumulated, and proposed to use this nitrite type nitrification carrier to perform nitrite type nitrification treatment (for example, Patent Document 1).

However, when the nitrification treatment equipment using this nitrite type nitrification support is applied to actual wastewater treatment, nitrite oxidation bacteria are mixed in the ammoniacal wastewater and mixed into the nitrification treatment equipment. When bacteria adhere to and grow on the carrier, the nitrification activity as a nitrite-type nitrification carrier decreases. Therefore, in order to recover the nitrification activity of the nitrite-type nitrification carrier, it is necessary to deactivate the nitrite-oxidizing bacteria attached and grown by periodically heating the nitrite-type nitrification carrier. For this reason, Patent Document 1 proposes to heat-treat the nitrite type nitrification carrier once every 3 to 12 months.
JP 2003-2111177 A

  However, when the nitrite-type nitrification carrier is heat-treated, nitrite-oxidizing bacteria are inactivated, but at the same time, ammonia-oxidizing bacteria are inactivated to a small extent. Therefore, if the nitrite type nitrification carrier is heat-treated together at a rate of once every 3 to 12 months, the nitrite type nitrification performance of the nitrification tank will temporarily decline sharply, and the ammonia oxidizing bacteria will return to the original nitrification again. Until the activity is recovered, there is a period in which the nitrite type nitrification reaction cannot be sufficiently performed, and there is a disadvantage that the nitrite type nitrification treatment cannot be stably performed.

  Moreover, in order to heat-treat a large amount of nitrite type nitrification supports at once, a large-capacity heating device and a heat retaining device are required, and there is a problem that the heating device becomes large.

  Recently, a wastewater treatment method using an anaerobic ammonia oxidation method has attracted attention (for example, JP-A-2001-37467). This anaerobic ammonia oxidation method is a method in which ammonia is used as a hydrogen donor, nitrous acid is used as a hydrogen acceptor, and ammonia and nitrous acid are simultaneously denitrified by an anaerobic ammonia oxidizing bacterium according to the following reaction formula.

1.0 NH ₄ + 1.32NO ₂ + 0.066HCO ₃ + 0.13H ⁺ → 1.02N ₂ + 0.26NO ₃ + 0.066CH ₂ O _0.5 N _0.15 + 2.03H ₂ O
According to this method, since ammonia is used as a hydrogen donor, there are merits such as greatly reducing the amount of methanol used for denitrification and reducing the amount of sludge generated. It is considered to be an effective method. However, as can be seen from the above formula, this method requires that the ratio of ammonia and nitrous acid be 1: 1.32. In order to stably form this ratio, the nitrite type nitrification performance is It is necessary that the fluctuation is small. Therefore, if there is a nitrification treatment method and apparatus that can reduce the fluctuation of nitrite type nitrification performance, it is suitable for obtaining water to be treated for wastewater treatment of anaerobic ammonia oxidation.

  Further, if there is a nitrification treatment method or apparatus that can reduce the fluctuation of nitrite type nitrification performance, it is effective in normal biological denitrification treatment (or denitrification treatment by autotrophic bacteria). In normal nitrification / denitrification treatment, a hydrogen donor such as methanol is required, and nitrous acid is converted into nitrogen gas via nitric acid. However, by denitrifying from nitrous acid, the amount of methanol used when reducing from nitrous acid via nitric acid can be reduced, and the amount of drug used can be reduced.

  The present invention has been made in view of such circumstances, and the fluctuation in nitrification performance due to heat treatment for recovering the nitrification activity of the nitrite-type nitrification carrier can be reduced, so that stable nitrification treatment can be performed. It is suitable for obtaining water to be treated for wastewater treatment of anaerobic ammonia oxidation method, and is suitable for ordinary biological denitrification treatment, and the heat treatment apparatus can be made compact. An object of the present invention is to provide a nitric acid type nitrification method and apparatus and a wastewater treatment apparatus.

In order to achieve the above object, claim 1 of the present invention is an ammoniacal nitrification tank in which a large number of nitrite-type nitrification carriers in which ammonia-oxidizing bacteria that nitrify ammonia to nitrite are preferentially accumulated are introduced. In the nitrite type nitrification method for nitrifying ammonia in wastewater into nitrite, a net-like container through which the nitrite type nitrification carrier does not pass is provided in a metering / heating tank as one tank, and the nitrification tank A metering step of metering the nitrite-type nitrification carrier in such a manner that the withdrawal amount is within a range of 0.5 to 2.5% of the total carrier amount by pulling out the nitrite-type nitrification carrier so that the container is full; -A heating process for recovering nitrite type nitrification activity by supplying warm water into the heating tank and heating the nitrite type nitrification support in the container; and the nitrite type nitrification support treated with the heat treatment Returning process to , Characterized by comprising a.

  According to claim 1, a part of the total amount of the nitrite-type nitrification carrier in the nitrification tank is periodically withdrawn and subjected to heat treatment, and then returned to the nitrification tank. Restores nitrification activity. At this time, the heat treatment for recovering the nitrification activity of the nitrite type nitrification carrier by controlling the withdrawal amount per day drawn from the nitrification tank within the range of 0.5 to 2.5% of the total carrier amount. Therefore, stable nitrification treatment can be performed. The inventors found that the ratio of the amount of extraction per day withdrawn from the nitrification tank to the total amount of carrier is an extremely important condition for stabilizing the treatment performance of the nitrite type in the nitrification tank. Is. That is, when the amount of extraction per day extracted from the nitrification tank is less than 0.5% of the total amount of the carrier, the nitrite oxidizing bacteria attached to the nitrite type nitrification carrier cannot be sufficiently sterilized when viewed from the whole nitrification tank. . As a result, the nitrite-type nitrification performance of the nitrification tank is lowered, so that nitric acid is generated in the treated water. On the other hand, if the daily withdrawal amount from the nitrification tank exceeds 2.5% of the total carrier amount, nitrite-oxidizing bacteria are sufficiently sterilized, but some ammonia-oxidizing bacteria are also sterilized. The nitrification activity of the nitric acid type nitrification carrier is reduced, and the nitrification performance of the nitrification tank is greatly reduced. Therefore, the nitrification performance of the nitrification tank is greatly reduced while the nitrite-type nitrification carrier having reduced activity is acclimatized to the original activity again.

  In the present invention, the ammoniacal wastewater means wastewater mainly composed of ammonia as a nitrogen component in the wastewater, and the same applies hereinafter.

  A second aspect of the present invention is characterized in that in the first aspect, the nitrite-type nitrification carrier is withdrawn every day. This is because the nitrite type nitrification carrier in the nitrification tank is partly extracted and heat-treated periodically to reduce the nitrification activity as if the entire carrier amount was heat-treated at once. However, if the interval between periodic withdrawals becomes longer, the ratio of nitrite-type nitrification carriers that have recovered nitrification activity gradually decreases in the nitrification tank, and the nitrification performance of the nitrification tank gradually decreases. is there. Therefore, it is preferable to carry out the heat treatment by extracting from the nitrification tank within a range of 0.5 to 2.5% every day.

  A third aspect is characterized in that, in the first or second aspect, the nitrite type nitrification carrier is a entrapping immobilization carrier. As fixing methods, there are adhesion fixation and entrapping fixation. In the case of adhesion fixation, a step of removing the nitrite type nitrification carrier from the nitrification tank, a step of heat treatment, a heat treatment of the nitrite type nitrification carrier There is a risk that microorganisms attached during the process of returning to the nitrification tank may be detached from the carrier. In that respect, since the entrapping immobilization includes the microorganisms in the gel, the nitrification activity can be further stabilized without the possibility that the microorganisms are detached from the carrier even after the above process.

According to a fourth aspect of the present invention, in order to achieve the above object, in a nitrification tank in which a large number of nitrite-type nitrification carriers that preferentially accumulate ammonia-oxidizing bacteria that nitrify ammonia to nitrite are introduced, In a nitrite-type nitrification apparatus for nitrifying ammonia into nitrite, a drawing line for drawing the nitrite-type nitrification carrier from the nitrification tank and a net-like container through which the nitrite-type nitrification carrier does not pass are in one tank. By pulling out the nitrite type nitrification carrier provided in a certain weighing / heating tank and drawn out by the drawing line so that the container is full, the drawing amount is 0.5 to 2.5% of the total carrier amount. a metering means for metering to be in the range of, has a hot water supply means for supplying hot water to said metering-heating chamber, heating means for heating the nitrite type nitrification carrier in the container, heated The physical and nitrite-type nitrification carrier is characterized in that and a return line back to the nitrification tank.

  Claim 4 is configured as an apparatus for carrying out the method of claim 1.

A fifth aspect of the present invention is characterized in that, in the fourth aspect, the measuring means includes a detecting means for detecting that the nitrite type nitrification carrier is full in the container.

  Thus, when the container is filled with the extracted nitrite type nitrification carrier, the extraction amount per day withdrawn from the nitrification tank should be within the range of 0.5 to 2.5% of the total carrier amount. In addition, an appropriate amount of nitrite-type nitrification carrier can be automated with a simple configuration.

  A sixth aspect is characterized in that in the fourth or fifth aspect, a cooling means for cooling the heated nitrite type nitrification carrier is provided in the return line. This is because the nitrite type nitrification carrier shrinks immediately after the heat treatment and the volume is reduced. That is, a screen for separating the nitrite-type nitrification carrier is usually provided at the treated water outlet of the nitrification tank. However, when the nitrite-type nitrification carrier is returned to the nitrification tank while being contracted, the nitrite-type nitrification carrier is visible on the screen. It may cause troubles such as clogging.

  According to a seventh aspect of the present invention, in order to achieve the object, ammonia and nitrous acid are simultaneously desorbed by anaerobic ammonia-oxidizing bacteria after the nitrite type nitrification treatment apparatus according to any one of the fourth to sixth aspects. An anaerobic ammonia oxidation apparatus for nitriding is provided.

  As described above, if an anaerobic ammonia oxidation apparatus is provided after the nitrite type nitrification apparatus of the present invention, the ratio of ammonia and nitrous acid suitable for performing the anaerobic ammonia oxidation method in the nitrification apparatus is high. The water to be treated of 1: 1.32 can be stably generated.

  As described above, according to the nitrite type nitrification method and apparatus of the present invention, fluctuations in the nitrite type nitrification performance due to heat treatment for recovering the activity of the nitrite type nitrification carrier can be reduced, so that it is stable. Nitrification treatment can be performed.

  In addition, according to the wastewater treatment apparatus of the present invention, the anaerobic ammonia oxidation apparatus is arranged after the nitrite type nitrification apparatus of the present invention, so that the wastewater treatment for the anaerobic ammonia oxidation method is performed. Treated water can be obtained appropriately. Furthermore, the present invention is effective in normal biological denitrification treatment (or denitrification treatment by autotrophic bacteria) because the amount of hydrogen donor such as methanol in the denitrification treatment can be reduced.

  Preferred embodiments of a nitrite type nitrification method and apparatus and a wastewater treatment apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 is a conceptual diagram of a nitrite type nitrification apparatus of the present invention.

  As shown in FIG. 1, a nitrite type nitrification apparatus 10 is mainly composed of a nitrite type nitrification tank 12 and a heat treatment apparatus 14 that heat-treats the nitrite type nitrification carrier 20 in the nitrification tank 12. Composed.

  Ammonia waste water (raw water) flows into the nitrification tank 12 by a raw water pump 18 through a raw water pipe 16. In the nitrification tank 12, a large number of nitrite-type nitrification carriers 20, 20... In which ammonia-oxidizing bacteria that nitrify ammonia to nitrite are preferentially accumulated are introduced. Ammonia waste water, nitrite-type nitrification carrier, Is contacted under aerobic conditions, and ammonia in the ammoniacal wastewater is nitrified to nitrous acid. The nitrification water that has been subjected to nitrite-type nitrification in the nitrification tank 12 is discharged out of the system through the treatment water pipe 22. A screen 24 is provided at the inlet position of the treated water pipe 22 in the nitrification tank 12, thereby preventing the nitrite type nitrification carrier 20 from flowing out along with the nitrification treated water.

  As the nitrite type nitrification carrier 20 to be introduced into the nitrification tank 12, either a entrapping immobilization carrier in which microorganisms are entrapped and immobilized inside the carrier or an adhesion immobilization carrier in which microorganisms are attached around the carrier can be used. . However, from the viewpoint of difficulty in detaching microorganisms during the heat treatment, the entrapping immobilization carrier is more preferable than the adhesion immobilization carrier.

  As a method for producing the entrapped immobilization type nitrite-type nitrification carrier 20, sludge of a complex microbial system having nitrification performance containing at least ammonia-oxidizing bacteria and nitrite-oxidizing bacteria was heat-treated in a range of 40 to 100 ° C. Thereafter, it is comprehensively fixed to either the monomer or the prepolymer. The heat treatment time is 60 minutes or more when the heat treatment temperature is 40 ° C. or more and less than 60 ° C., and 40 minutes or more when the heat treatment temperature is 60 ° C. or more and less than 80 ° C. In the range of 80 ° C. or more and 100 ° C. or less, it is preferably 20 minutes or more. As the monomer material, acrylamide, methylenebisacrylamide, triacryl formal and the like are preferable. The prepolymer material is preferably polyethylene glycol diacrylate or polyethylene glycol methacrylate, and derivatives thereof can be used. The shape of the nitrite type nitrification carrier is spherical or cylindrical inclusion carrier, string inclusion carrier, porous inclusion, non-woven fabric, honeycomb, sponge, etc. inclusion carrier with many irregularities improves contact efficiency and improves nitrification performance . In addition, heat treatment may be performed after the sludge is comprehensively fixed to either the monomer or the prepolymer, and in this case, heat treatment is preferably performed in the range of 30 to 90 ° C for 1 hour or longer. Thereby, a nitrite-type nitrification carrier in which ammonia-oxidizing bacteria that nitrify ammonia to nitrite are preferentially accumulated can be produced. Examples of complex microbial sludge include sludge from lakes, rivers, and sea, soil from the surface, sewage treatment wastewater, and factory wastewater.

  As a method for producing an adhesion-immobilized nitrite-type nitrification carrier, the composite microorganism sludge is heat-treated in the range of 40 to 100 ° C. and then adhered and fixed to the adhesion-immobilizing material. In adhesion fixation, fixing materials having many irregularities such as spherical or cylindrical carrier materials, string-like materials, gel-like carriers, non-woven materials, and the like are easily adhered, and the nitrification performance is improved. Furthermore, a granule type nitrite type nitrification carrier utilizing self-organization of microorganisms may be used.

  The heat treatment apparatus 14 mainly heats the extraction pipe 26 for extracting the nitrite type nitrification carrier 20 from the nitrification tank 12, the measuring tank 28 for measuring the extraction amount of the nitrite type nitrification carrier 20, and the nitrite type nitrification carrier 20. A heating tank 30 to be processed, a cooling tank 32 for cooling the nitrite type nitrification carrier 20, and a return pipe 34 for returning the nitrite type nitrification carrier 20 to the nitrification tank 12 are configured. In addition, the measuring tank 28 and the heating tank 30, and the heating tank 30 and the cooling tank 32 are connected by a first water pipe 36 and a second water pipe 38, respectively. The extraction pipe 26, the first water supply pipe 36, the second water supply pipe 38, and the return pipe 34 are provided with a drawing pump 40, a first feed pump 42, a second feed pump 44, and a return pump 45, respectively.

  A container 46 formed of a metal mesh or a plastic mesh is provided in the measuring tank 28, and one end of the extraction pipe 26 is inserted into the container 46 from the upper surface, and the lower surface can be opened and closed by an opening / closing drive unit 48. It is formed. It is necessary for the mesh of the stitches of the container 46 not to pass the nitrite type nitrification carrier 20. The capacity of the container 46 is such that when the nitrite type nitrification carrier 20 is filled in the container 46, the withdrawal amount withdrawn from the nitrification tank 12 is in the range of 0.5 to 2.5% of the total carrier amount. It is formed to become. Further, a sensor 50 for detecting that the inside of the container 46 is filled with the nitrite type nitrification carrier 20 is provided at the upper surface position of the container 46, and a detection signal of the sensor 50 is input to the control device 52. Further, the control device 52 also performs the ON / OFF control of the drawing pump 40, the first feed pump 42, the second feed pump 44, and the return pump 45 and the opening / closing control of the opening / closing drive unit 48.

  According to the heat treatment apparatus 14 configured as described above, when the control device 52 turns on the extraction pump 40, the nitrite type nitrification carrier 20 in the nitrification tank 12 is discharged from the nitrification tank 12 via the extraction pipe 26. And flows into the container 46 together, and only the nitrite type nitrification carrier 20 is stored in the container 46. When the sensor 50 detects that the nitrite-type nitrification carrier 20 is full in the container, a detection signal is sent to the control device 52, and the control device 52 turns off the extraction pump 40. Thereby, the extraction amount per day extracted from the nitrification tank 12 can be measured. When the extraction amount of the nitrite type nitrification carrier 20 is measured, the control device 52 controls the opening / closing drive unit 48 to open the lower surface of the container 46 and turn on the first feed pump 42 to turn on the nitrite type in the container 46. The nitrification carrier 20 is sent to the heating tank 30 together with the waste water in the measuring tank 28. When the feeding is completed, the first feed pump 42 is turned off. The metering of the nitrite type nitrification carrier 20 in the metering tank 28 is not limited to the above-described method, and the above-described withdrawal amount is obtained when the container 46 is hung on a weighing scale and reaches a predetermined weight. May be within the range of 0.5 to 2.5% of the total carrier amount. In short, any method can be used as long as it can automatically measure the amount of extraction from the nitrification tank 12 per day.

  A heater 54 is provided in the heating tank 30 to heat the nitrite type nitrification carrier 20 sent from the measuring tank 28. The heat treatment conditions at this time are the same as the heat treatment conditions at the time of manufacturing the nitrite type nitrification carrier 20 described above. By this heat treatment, the nitrite oxidizing bacteria adhering to the nitrite type nitrification carrier 20 mixed with the waste water in the nitrification tank 12 are sterilized. When the heat treatment in the heating tank 30 is completed, the control device 52 turns on the second feed pump 44 to cool the nitrite-type nitrification carrier 20 in the heating tank 30 together with the waste water in the heating tank 30 to the cooling tank 32. Send to. When the feeding is finished, the second feed pump 44 is turned off.

  Above the cooling tank 32, a cold water supply pipe 56 for supplying cold water is extended, and the cold water is supplied to the cooling tank 32, whereby the nitrite type nitrification carrier 20 heated in the heating tank 30 is supplied to the nitrification tank 12. It is cooled to the same level as the temperature of the nitrite type nitrification carrier 20 inside. In this case, it is preferable to provide a discharge pipe 58 for discharging only the warm waste water from the heating tank 30 without discharging the nitrite type nitrification carrier 20 at the bottom of the cooling tank 32. When the cooling of the nitrite-type nitrification carrier 20 in the cooling tank 32 is completed, the control device 52 turns on the return pump 45 to put the nitrite-type nitrification carrier 20 cooled in the cooling tank 32 into the cooling tank 32. It is sent to the nitrification tank 12 together with cold water. When the feeding is completed, the return pump 45 is turned off.

  Note that the heating frequency is not necessarily performed once a day. For example, the heating frequency may be performed once every two days, or the heat treatment for two days may be performed collectively. Further, the nitrite-type nitrification carrier 20 to be heated for one day may be heat-treated in several times. However, if the heat treatment interval is too long, the ratio of the nitrite-type nitrification carrier 20 whose nitrification activity has been recovered gradually decreases in the nitrification tank 12, and the nitrification performance of the nitrification tank 12 gradually decreases. . Therefore, it is preferable to carry out the heat treatment by extracting from the nitrification tank 12 once a day within a range of 0.5 to 2.5%.

  As described above, according to the present invention, a part of the total amount of the nitrite type nitrification carrier 20 in the nitrification tank 12 is periodically extracted and subjected to heat treatment, and then returned to the nitrification tank 12 to thereby form the nitrite type. The nitrification activity of the nitrification carrier 20 was restored, and the extraction amount per day withdrawn from the nitrification tank 12 was controlled within the range of 0.5 to 2.5% of the total carrier amount. Thereby, since the fluctuation | variation of the nitrification performance of the nitrification tank 12 by the heat processing for recovering the nitrification activity of the nitrite type nitrification carrier 20 can be reduced, stable nitrite type nitrification treatment can be performed. Further, since the cooling tank 32 is provided so that the nitrite type nitrification carrier 20 whose volume is contracted by the heat treatment in the heating tank 30 is returned to the original volume, the nitrite type nitrification carrier 20 is a screen of the nitrification tank 12. No troubles such as clogging 24 occur.

  FIG. 2 is an explanatory view of a metering / heating tank 60 in which metering and heating of the nitrite type nitrification carrier 20 can be performed in the same tank. In addition, the same member as the member of FIG. 1 is attached | subjected and demonstrated.

  As shown in FIG. 2, it is the same that a container 46 for storing the nitrite type nitrification carrier 20 drawn out from the nitrification tank 12 is provided in the measurement / heating tank 60. An extraction pipe 26 for extracting the nitrification carrier 20, a hot water supply pipe 62 for supplying hot water, and a discharge pipe 66 with a valve 64 for discharging waste water flowing together with the nitrite type nitrification carrier 20 from the nitrification tank 12 are provided. When the nitrite type nitrification carrier 20 is subjected to heat treatment, the nitrite type nitrification carrier 20 in the nitrification tank 12 is pulled out by the pump 40 through the extraction pipe 26 until the inside of the container 46 becomes full. When the drawing is completed, the valve 64 of the discharge pipe 66 is opened to discharge the waste water from the metering / heating tank 60 to the nitrification tank 12. The discharge destination may be other than the nitrification tank 12. Next, hot water is supplied from the hot water supply pipe 62 into the metering / heating tank 60, and the nitrite type nitrification carrier 20 drawn into the container 46 is heated. Thereby, the measurement and heating of the nitrite type nitrification support | carrier 20 can be performed in the same tank, and it contributes to size reduction of the heat processing apparatus 14. FIG.

  FIG. 3 is a conceptual diagram of the wastewater treatment apparatus 70 of the present invention, and anaerobic ammonia oxidation in which ammonia and nitrous acid are simultaneously denitrified by anaerobic ammonia oxidizing bacteria at the subsequent stage of the nitrite type nitrification apparatus 10 described above. A device 72 is provided. In addition, the same code | symbol is attached | subjected to the member already demonstrated with the nitrite type nitrification apparatus 10, and description is abbreviate | omitted. In addition, although only the main structure was illustrated in the heat processing apparatus 14 of FIG. 3, it is the same as that of the heat processing apparatus 14 demonstrated in FIG.

  As shown in FIG. 3, a diverter 74 is provided in front of the nitrification tank 12 to divert ammonia waste water into two parts, the nitrification apparatus 10 and the anaerobic ammonia oxidation apparatus 72. That is, the raw water pipe 16 is branched into two at the outlet of the flow divider 74, one branched raw water pipe 16 a is connected to the nitrification tank 12, and the other branched raw water pipe 16 b reaches the anaerobic ammonia oxidizer 72. Connected in the middle of the treated water pipe 22.

  In order to remove the nitrogen component in the ammonia waste water by the anaerobic ammonia oxidation method in the waste water treatment apparatus 70, 57% of the ammonia waste water is diverted to the nitrite type nitrification apparatus 10 by the flow divider 74, and the remaining 43 % Is diverted to flow directly into the anaerobic ammonia oxidizer 72. Then, by nitrifying ammonia in the ammoniacal wastewater into nitrous acid by the nitrification apparatus 10, the ratio of the ammonia to the treated water flowing into the anaerobic ammonia oxidation apparatus 72 and nitrous acid is 1: 1.32. Control to the ratio of ammonia oxidation method. In this case, by using the nitrite type nitrification apparatus 10 of the present invention, the nitrification performance of nitrifying ammonia in ammonia wastewater to nitrite can be stabilized, so that it flows into the anaerobic ammonia oxidation apparatus 72. It is possible to stably control the ratio of ammonia and nitrous acid to be treated to the ratio of the anaerobic ammonia oxidation method of 1: 1.32. Therefore, the nitrogen removal performance by the anaerobic ammonia oxidation device 72 is improved.

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

(Comparative example)
As shown in FIG. 4, the comparative example is a case where a nitrite type nitrification test was conducted in a conventional nitrification tank 80 in which the heat treatment of the nitrite type nitrification carrier 20 is performed collectively. The heat-treated nitrite type nitrification carrier 20 (encapsulated immobilization carrier) was put into a nitrification tank 80, and ammonia waste water was passed through. Industrial wastewater was used as ammoniacal wastewater (raw water). As the nitrite type nitrification carrier, a nitrite-type nitrification carrier formed into a cube shape with a side of 3 mm was previously heated in a hot water bath at 60 ° C. for 1 hour. The ammonia nitrogen concentration (NH ₄ —N) of this industrial wastewater was 350 to 440 mg / L. The pH of the wastewater was controlled to 7.0 to 8.0 by a pH controller, and the dissolved oxygen concentration (DO) was set to 1.0 to 2.0 mg / L by a DO controller.

The water quality result of the treated water in the comparative example is shown in FIG. As can be seen from the ammonia nitrogen concentration (NH ₄ -N) and nitrite nitrogen concentration (NO ₂ -N) of the treated water, nitrification activity rises about 3 to 4 weeks after the start of operation, and nitrite type nitrification reaction Started. It was confirmed that a stable nitrite-type nitrification reaction was maintained until about 210 days after the start of operation. However, from 210 days after the start of operation, the concentration of nitrite nitrogen (NO ₂ -N) decreased rapidly. This is because the nitrite-oxidizing bacteria that flowed into the nitrification tank 80 together with the industrial wastewater adhered to and propagated on the nitrite-type nitrification carrier, and the nitrite oxidation activity rose. Was detected. Therefore, on the 240th day, all of the nitrite-type nitrification carrier in the nitrification tank 00 was recovered, and the attached nitrite-oxidizing bacteria were sterilized by heat treatment again. The heat treatment conditions were performed by crushing in a hot water bath at 60 ° C for 1 hour. As a result, the performance could be recovered from about the 258th day, and a nitrite type nitrification reaction could be performed.

  However, as apparent from FIG. 5, a large amount of ammonia remained in the treated water from the 240th day to the 258th day after the start of operation. This is because the heat treatment of the nitrite type nitrification carrier also slightly affected the ammonia oxidizing bacteria, and the nitrite type nitrification activity decreased. From the results of this comparative example, it is clear that when the nitrite type nitrification carrier 20 in the nitrification tank 80 is pulled out at a time and subjected to heat treatment, a period during which nitrite type nitrification cannot be performed at all will occur. became.

(Example)
In the example, a nitrite type nitrification test was performed using the same industrial wastewater and nitrite type nitrification carrier 20 as in the comparative example, using the nitrite type nitrification apparatus 10 of the present invention of FIG. Is. The nitrite-type nitrification carrier 20 is periodically withdrawn from the nitrification tank 12 at a rate of once a day, heat-treated with the heat treatment device 14 and returned to the nitrification tank 12, and the amount of carrier withdrawal (%) at one time is nitrification. Tested as 0.1% to 4% of the total amount of carrier in tank 12. That is, a plurality of nitrification tanks 12 were prepared, and the carrier withdrawal amount (%) was set differently within the range of 0.1% to 4% carrier withdrawal amount (%) for each nitrification tank.

  FIG. 6 shows the relationship between the nitrite type nitrification rate (%) and the extraction amount (%) of the nitrite type nitrification carrier.

  Here, the amount of carrier withdrawal (%) shown on the horizontal axis is the ratio of the nitrite type nitrification carrier 20 drawn per day to the total amount of carrier in the entire nitrification tank, and the nitrite type nitrification shown on the vertical axis. The rate (%) was calculated by the following formula.

Nitrite nitrogen concentration in treated water (NO ₂ -N)
Nitrite-type nitrification rate (%) ＝ ───────────────────── × 100
Ammonia nitrogen concentration of wastewater (NH ₄ -N)
As can be seen from FIG. 6, when the carrier withdrawal amount (%) from the nitrification tank 12 is increased, the nitrite type nitrification rate (%) increases rapidly, and the carrier withdrawal amount (%) is 0.5%. At that time, the nitrite type nitrification rate (%) reached a maximum of about 90%. When the carrier withdrawal amount (%) is further increased, the nitrite type nitrification rate (%) gradually decreases, and when the carrier withdrawal amount (%) is 2.5%, the nitrite type nitrification rate (%) It becomes about 75% and then decreases rapidly. Thus, when the amount of extraction per day extracted from the nitrification tank 12 is less than 0.5% of the total amount of the carrier, nitrite oxidizing bacteria adhering to the nitrite type nitrification carrier 12 when viewed from the entire nitrification tank 12 are sufficiently obtained. It cannot be sterilized. Thereby, since the nitrite type nitrification performance of the nitrification tank 12 is lowered, nitric acid is generated in the treated water. On the contrary, if the amount of extraction per day that is extracted from the nitrification tank 12 exceeds 2.5% of the total amount of the carrier, nitrite oxidizing bacteria are sufficiently sterilized, but part of ammonia oxidizing bacteria is also sterilized. The proportion of the nitrite-type nitrification carrier 20 that is being acclimatized in the nitrification tank 12 increases, and the nitrification performance of the nitrification tank 12 decreases. That is, even if the carrier withdrawal amount (%) is less than 0.5% and is too small or more than 2.5%, the nitrite type nitrification rate (%) is lowered and the nitrification performance of the nitrification tank 12 is reduced. It turns out that it gets worse.

  As a result of this example, a part of the total carrier amount of the nitrite type nitrification carrier in the nitrification tank 12 is periodically extracted and heat-treated, so that the whole carrier amount is heat-treated at the same time as in the comparative example. Although there is no decrease in nitrification activity like this, it means that if the amount of extraction per day is wrong, the nitrification performance of the nitrification tank 12 decreases. Accordingly, the nitrite-type nitrification carrier 20 is periodically extracted and heat-treated, and the heat-treated nitrite-type nitrification carrier 20 is returned to the nitrification tank 12, and the extraction amount per day in the nitrification tank 12 is extracted. It is important to control the amount within the range of 0.5 to 2.5% of the total carrier amount, whereby a high nitrite nitrification rate can be obtained.

  In addition, as for the hot water amount (heat amount) of the heating tank 30 used during the heat treatment, the maximum value of the carrier withdrawal amount (%) is set to 2.5%, so a small heating tank 30 is sufficient, and the equipment is greatly reduced. Can be planned.

Conceptual diagram of nitrite type nitrification apparatus of the present invention Schematic diagram of a metering / heating tank that allows the nitrite-type nitrification carrier to be drawn and weighed in one tank. Conceptual diagram of the wastewater treatment apparatus of the present invention Conceptual diagram of conventional nitrite type nitrification equipment The figure which showed the result of the comparative example which heat-processed the nitrite type nitrification support | carrier collectively with the conventional nitrite type nitrification apparatus. The relationship between the nitrite type nitrification rate (%) and the extraction amount (%) of the nitrite type nitrification carrier when the nitrite type nitrification carrier is periodically heat-treated with the nitrite type nitrification device of the present invention was shown. Figure

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Nitrite type nitrification apparatus, 12 ... Nitrification tank, 14 ... Heat processing apparatus, 16 ... Raw water piping, 18 ... Raw water pump, 20 ... Nitrite type nitrification support, 22 ... Treatment water piping, 24 ... Screen, 26 ... Pull-out pipe, 28 ... measuring tank (measuring means), 30 ... heating tank (heating means), 32 ... cooling tank (cooling means), 34 ... return pipe, 36 ... first water pipe, 38 ... second water pipe, 40 DESCRIPTION OF SYMBOLS ... Extraction pump, 42 ... 1st feed pump, 44 ... 2nd feed pump, 45 ... Return pump, 46 ... Container, 48 ... Opening / closing drive part, 50 ... Sensor, 52 ... Control apparatus, 54 ... Heater, 56 ... Cold water supply Piping, 58 ... Discharge pipe, 60 ... Metering / heating tank, 62 ... Warm water supply pipe, 64 ... Valve, 66 ... Discharge pipe, 70 ... Waste water treatment device, 72 ... Anaerobic ammonia oxidation device, 74 ... Shunt

Claims (7)

Nitrite-type nitrification that nitrifies ammonia in ammonia wastewater to nitrite in a nitrification tank in which a large number of nitrite-type nitrification carriers that preferentially accumulate ammonia-oxidizing bacteria that nitrify ammonia to nitrite In the processing method,
A net-like container through which the nitrite-type nitrification carrier does not pass is provided in a weighing / heating tank which is one tank, and by pulling out the nitrite-type nitrification carrier in the nitrification tank so that the container is full, A metering step of weighing so that the withdrawal amount is in the range of 0.5 to 2.5% of the total carrier amount;
A heating step of recovering the nitrite type nitrification activity by supplying hot water into the metering / heating tank and heating the nitrite type nitrification carrier in the container;
And a step of returning the heat-treated nitrite-type nitrification carrier to the nitrification tank . 2. The nitrite type nitrification method according to claim 1, wherein the nitrite type nitrification carrier is withdrawn every day. 3. The nitrite type nitrification treatment method according to claim 1, wherein the nitrite type nitrification carrier is a entrapping immobilization carrier. Nitrite-type nitrification that nitrifies ammonia in ammonia wastewater to nitrite in a nitrification tank filled with a large number of nitrite-type nitrification carriers that preferentially accumulate ammonia-oxidizing bacteria that nitrify ammonia to nitrite In the processing device,
An extraction line for extracting the nitrite-type nitrification carrier from the nitrification tank;
A net-like container through which the nitrite-type nitrification carrier does not pass is provided in a weighing / heating tank, which is a single tank, and the nitrite-type nitrification carrier pulled out by the drawing line is pulled out so that the container is full. A weighing means for weighing so that the withdrawal amount is in the range of 0.5 to 2.5% of the total carrier amount,
A heating means for supplying hot water into the weighing / heating tank, and heating means for heat-treating the nitrite type nitrification carrier in the container;
A nitrite-type nitrification treatment apparatus, comprising: a return line for returning the heat-treated nitrite-type nitrification carrier to the nitrification tank. The weighing means includes
5. The nitrite type nitrification apparatus according to claim 4, further comprising detection means for detecting that the nitrite type nitrification carrier is full in the container. 6. The nitrite type nitrification apparatus according to claim 4 or 5, wherein a cooling means for cooling the heated nitrite type nitrification carrier is provided in the return line. An anaerobic ammonia oxidizing apparatus for simultaneously denitrifying ammonia and nitrous acid by anaerobic ammonia oxidizing bacteria is provided downstream of the nitrite type nitrification treatment apparatus according to any one of claims 4 to 6. Wastewater treatment equipment.

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