KR20150083435A - Operating method for wastewater treatment apparatus - Google Patents

Abstract

The present invention provides a method for operating a wastewater treatment apparatus which can stably remove nitrogen from nitrogen-containing waste water containing methanol. The waste wastewater treatment apparatus (1) continuously treats the nitrogen-containing waste water with anaerobic ammonia oxidation bacteria and includes: a concentration reducing means (12a, 12b) which reduce concentration of methanol included in the nitrogen-containing wastewater; and a nitrogen removal tank (30) which converts ammonia nitrogen included in the nitrogen-containing wastewater and nitrate nitrogen generated by partial oxidation of ammonia nitrogen, into nitrogen gas by anaerobic ammonia oxidation bacteria. The concentration reducing means (12a, 12b) reduces concentration of methanol included in the nitrogen-containing wastewater to be 30 mg/L if the concentration of methanol, included in the nitrogen-containing wastewater entering into the nitrogen removal tank (30), is greater than 30 mg/L.

Description

[0001] OPERATING METHOD FOR WASTEWATER TREATMENT APPARATUS [0002]

The present invention relates to a method of operating a wastewater treatment apparatus. More particularly, the present invention relates to a method of operating a wastewater treatment apparatus that treats nitrogen wastewater containing ammonia nitrogen by anaerobic ammonia oxidation.

Wastewater discharged from ordinary households or workplaces may contain nitrogen components such as ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and organic nitrogen. Such nitrogen-containing wastewater containing nitrogen components has a phenomenon in which direct drainage to a water environment is regulated because it causes nutrient enrichment and lowering of dissolved oxygen concentration in lakes and rivers, etc. . Therefore, at the time of discharging the nitrogen-containing wastewater, generally, a nitrogen-containing wastewater treatment for oxidizing and decomposing or removing the nitrogen component is performed. As a method for treating low nitrogen concentration wastewater, a method of removing an ion species containing a nitrogen component by ion exchange or a method of performing an oxidative decomposition treatment by using chlorine, ozone or the like is used. On the other hand, biological treatment using microorganisms is often employed as a method for treating nitrogenous waste water at a high concentration from a medium concentration.

Conventionally, as the biological treatment, the oxidation reaction of ammonia nitrogen using ammonia oxidizing bacteria belonging to the genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, And oxidation reaction of nitrite nitrogen with nitrite type oxidizing bacteria belonging to the genus Nitrobacter, Nitrospina, Nitrococcus and Nitrospira, The nitrification treatment is a nitrification denitrification treatment which is a combination of anaerobic denitrification using heterotrophic bacteria such as Pseudomonas denitrificans.

However, in the nitriding denitration treatment, a nitriding tank for performing an aerobic nitriding treatment is generally operated under a nitrogen load of 0.2 kg-N / m ³ / day to 0.3 kg-N / m ³ / day a denitrification tank for performing extent, the anaerobic denitrification process in, it is required to run in a nitrogen volume load 0.2kg-N / m ³ / day ~0.4kg-N / m the range of from ³ / day or so. In the case of treating general nitrogen wastewater having a total nitrogen concentration of 30 mg / L to 40 mg / L in a load of this range, the nitrification tank is maintained for 6 hours to 8 hours, the denitrification tank is maintained for 5 hours to 8 hours It is necessary to design a large-scale treatment tank in accordance with this, so that the treatment cost is high. In addition, since it is necessary to add an organic matter such as methanol in the anaerobic denitrification treatment, the operation cost is high.

Recently, as disclosed in Patent Document 1, development of a wastewater treatment method using an anaerobic ammonia oxidation reaction (ANAMMOX; Anaerobic Ammonium Oxidation) is underway. The anaerobic ammonia oxidation reaction is a reaction in which ammonia is used as a hydrogen donor and nitrite is used as a hydrogen acceptor to carry out denitrification at once under anaerobic conditions.

1.00NH 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 ··· ( scheme 1)

Since the anaerobic ammonia oxidation reaction is a reaction in which anaerobic ammonium bacteria as an autotrophic bacterium (anammox bacteria) react with ammonia as a hydrogen donor, it is necessary to add an organic substance such as methanol in the anaerobic denitrification using this reaction There is an advantage that the operation cost is reduced as compared with the conventional nitrification denitration treatment. It is also said that since the amount of growth of the anaerobic ammonium oxidizing bacteria is small through wastewater treatment, the amount of waste sludge can be suppressed. On the other hand, it is known that the activity of anaerobic ammonium oxidizing bacteria is inhibited by nitrous acid, pH, various organic substances, etc., and proper treatment conditions must be managed in order to maintain effluent treatment efficiency.

For example, Non-Patent Document 1 discloses an analysis of the influence of an organic compound on anaerobic ammonia bacteria in a batch processing test system, and it is disclosed that the activity of the anaerobic ammonium oxidizing bacteria is completely lost at a methanol concentration of 0.5 mM have.

Non-Patent Document 2 also describes the methanol inhibition effect in a continuous treatment test system. After raw water (raw water) having a methanol concentration of 1.7 mM is continuously treated for 80 hours, the activity of the anaerobic ammonium oxidizing bacteria It is reported that it has decreased to 46%.

In these Non-Patent Documents 1 and 2, it has been shown that even when the methanol exposure is stopped, the activity of the anaerobic ammonium oxidizing bacteria is not restored, and the inhibition of the activity by methanol is an irreversible action.

Japanese Patent Application Laid-Open No. 2001-037467

Guven D. et al., Propionate Oxidation and Methanol Inhibition of Anaerobic Ammonium-Oxidizing Bacteria, Applied and Environmental Microbiology (2005) vol. 71, No. 2, p. K. Isaka, Y. Suwa, Y. Kimura, T. Yamagishi, T. Sumino, S. Tsuneda, Anaerobic Ammonium Oxidation (anammox) irreversibly inhibited by methanol, Applied Microbiology and Biotechnology (2008) 81, p.379-385

As disclosed in Non-Patent Document 1 and Non-Patent Document 2, it is known that methanol, which is known to inhibit the denitrification activity of anaerobic ammonia-oxidizing bacteria, can be incorporated into the nitrogen wastewater to be treated wastewater. For example, ammonia production facilities exist as a place where large quantities of nitrogen wastewater are generated, but methanol is often produced in ammonia production facilities. This is because ammonia and methanol can be synthesized by using steam reforming, and many of them can be commonly used in the production facilities used for their synthesis. Therefore, the nitrogen-containing wastewater drained from the ammonia production facility is often mixed with methanol. In addition, as shown in the multistage wastewater treatment facility, a heterotrophic denitrification tank or an organic matter treatment tank using heterotrophic bacteria is disposed at the front stage of the denitrification tank that holds the anaerobic ammonium oxidizing bacteria, Or the heterotrophic denitrification tank is disposed at the downstream end of the denitrification tank and the treated water containing the heterotrophic denitrification tank is returned to the denitrification tank. Therefore, the methanol added as the hydrogen donor in the denitrification tank or the organic material treatment tank may be discharged without being magnetized, and may be introduced into the subsequent denitrification tank.

In the continuous treatment of nitrogen purge wastewater, when methanol of high concentration flows into the denitrification tank in this way, denitrification activity of the anaerobic ammonium oxidizing bacteria is inhibited and irreversible deterioration is shown. As the continuous treatment is continued, the level of the denitrification activity is lowered . However, it is known that the anaerobic ammonium oxidizing bacteria are prolonged in the induction period of proliferation and the proliferation rate is very slow, and it is difficult to complement the level of degraded denitrification activity by the proliferation of the cells. In addition, in order to prevent methanol from flowing in, an organic matter treatment tank is provided at the front end, and the organic matter treatment tank is operated so as to completely decompose methanol or to restrict the addition of methanol at the front end. It is not preferable from the viewpoint of processing efficiency and processing cost because the whole design is restricted. Therefore, in the wastewater treatment for treating nitrogen wastewater with anaerobic ammonia-oxidizing bacteria, it is possible to stably denitrify the nitrogen wastewater containing methanol by maintaining the activity of the anaerobic ammonia-oxidizing bacteria at a high level There is a need for a method.

Accordingly, an object of the present invention is to provide a method for operating a wastewater treatment apparatus capable of stably denitrifying nitrogen-containing wastewater containing methanol.

In order to solve the above problems, a method for operating a wastewater treatment apparatus according to the present invention is a method for operating a wastewater treatment apparatus that continuously treats nitrogenous wastewater containing ammonia nitrogen by anaerobic ammonia oxidizing bacteria, A concentration lowering means for lowering the concentration of methanol in the nitrogen-containing wastewater; a concentration reducing means for lowering the ammonia nitrogen contained in the nitrogen-containing wastewater and a nitrite nitrogen generated by oxidation of a part of the ammonia nitrogen to an anaerobic ammonia oxidizing bacteria Wherein the concentration lowering means reduces the concentration of methanol in the nitrogen-containing wastewater to a concentration lower than the concentration of the nitrogen-containing wastewater when the concentration of methanol in the nitrogen-containing wastewater to be introduced into the denitrification tank exceeds 30 mg / L To 30 mg / L or less.

Another aspect of a method of operating a wastewater treatment apparatus according to the present invention is a method for operating a wastewater treatment apparatus that continuously treats nitrogenous wastewater containing ammonia nitrogen by anaerobic ammonium oxidizing bacteria, Wherein the ammonia nitrogen contained in the nitrogen wastewater and the nitrite nitrogen generated by oxidation of a part of the ammonia nitrogen are introduced into the nitrogen wastewater by the anaerobic ammonia oxidizing bacteria, And the methanol supply means supplies methanol to the nitrogen-containing wastewater so that the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank is 0.5 mg / L or more and 30 mg / L or less .

According to the present invention, it is possible to provide a method of operating a wastewater treatment apparatus capable of stably denitrifying nitrogen-containing wastewater containing methanol.

1 is a schematic view showing an application example of a wastewater treatment apparatus for treating nitrogen-containing wastewater.
2 is a view showing a schematic configuration of a wastewater treatment apparatus to which an operation method according to the first embodiment is applied.
3 is a view showing a schematic configuration of a wastewater treatment apparatus to which an operation method according to the second embodiment is applied.
Fig. 4 is a diagram showing an example of a schematic configuration of a wastewater treatment apparatus according to a modification.
5 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Example 1-1.
6 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Example 1-2.
7 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Examples 1-3.
8 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Comparative Example 1. Fig.
9 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Example 2-1.
10 is a graph showing the relationship between the methanol concentration of the nitrogen-containing wastewater and the nitrogen removal rate in Example 2-2.

Hereinafter, a method of operating a wastewater treatment apparatus according to an embodiment of the present invention will be described in detail. In the drawings, the same parts are denoted by the same reference numerals, and a description of the overlapping parts is omitted.

A method of operating a wastewater treatment apparatus according to the present embodiment relates to a method of operating a wastewater treatment apparatus that continuously treats nitrogenous wastewater containing ammonia nitrogen by using anaerobic ammonium oxidizing bacteria. Nitrogen wastewater to be treated is generated, for example, at workplaces such as ammonia production facilities, sewage treatment plants, metal refineries, semiconductor factories, and general households, and contains ammonia nitrogen as a main nitrogen component. Nitrogen wastewater drained from a workplace or the like is pretreated in a precipitation separation tank, an oil water separation tank, another denitrification tank, an organic material treatment tank and the like, and then provided for denitrification treatment by anaerobic ammonium oxidizing bacteria as necessary. In the wastewater treatment apparatus to which the operation method related to the present embodiment is applied, such nitrogen wastewater is continuously introduced into an denitrification tank for holding anaerobic ammonium oxidizing bacteria, and ammonia nitrogen is converted into nitrogen gas by anaerobic ammonia oxidation Oxidation conversion and processing.

1 is a schematic view showing an application example of a wastewater treatment apparatus for treating nitrogen-containing wastewater.

As shown in Fig. 1 (a), a wastewater treatment apparatus for treating nitrogen wastewater using an anaerobic ammonia oxidation reaction is divided into a nitrification tank 20 and a denitrification tank (anaerobic ammonia oxidation tank) 30 and anaerobic ammonia oxidation A two-piece wastewater treatment apparatus for performing a reaction is generally used. In the nitrification tank 20, a part of the ammonia nitrogen contained in the raw water (nitrogen wastewater) to be introduced is partially oxidized to nitrite nitrogen so that the ratio of the ammonia nitrogen and nitrite nitrogen is changed to the denitrification tank 30 ). ≪ / RTI > In the denitrification tank 30, an ammonia nitrogen is used as a hydrogen donor, nitrite nitrogen generated in a nitrification tank is used as a hydrogen acceptor, anaerobic ammonia oxidation reaction is carried out, and most of the nitrogen component is denitrified by nitrogen gas. The remaining part of the nitrogen component is discharged in the form of nitrate nitrogen in the form of nitrogen remaining in the treated water.

When such a wastewater treatment apparatus is applied, the organic matter treatment tank 60 may be provided at the front end of the nitrification tank 20 as shown in Fig. 1 (b). In the organic matter treatment tank 60, a treatment for aerobic decomposition treatment of the organic matter contained in the raw water by using activated sludge or the like is performed to lower the biological oxygen demand (BOD) of the nitrogen waste water in advance. Further, as shown in Fig. 1 (c), a denitrifying tank (heterotrophic denitrifying tank) 70 may be provided. In the heterotrophic denitrification tank 70, the nitrogen component contained in the raw water is reduced by using the conventional heterotrophic denitrifying bacteria, and the treated water of the nitrification tank 20 or the denitrification tank 30 is returned as necessary A treatment for lowering the nitrogen component concentration of the nitrogen-containing wastewater is performed. 1 (d), the heterotrophic denitrification tank 70 may be provided at the downstream end of the denitrification tank (anaerobic ammonia oxidation tank) 30 as well. At the downstream end of the denitrification tank 30, the nitrate nitrogen generated by the anaerobic ammonia oxidation reaction is reduced.

In the continuous treatment of the wastewater, the source and dilution rate of the raw water (nitrogen wastewater) to be treated, the mixing ratio of raw water derived from a plurality of origins, the pretreatment conditions, and the like are changed so that the denitrification tank (anaerobic ammonia oxidation tank) The concentration of methanol in the nitrogen-containing wastewater to be introduced may fluctuate. For example, in the constitution of the wastewater treatment apparatus exemplified in Figs. 1 (a), (b) and (d), when methanol to be treated is contained in raw water to be treated, (30). 1 (b), untreated methanol is introduced into the denitrification tank 30 depending on the treatment conditions of the organic material treatment tank 60 and the methanol concentration. 1 (c) and 1 (d), when methanol is added as a hydrogen donor in the heterotrophic denitrification tank 70, the methanol is not reacted in the heterotrophic denitrification tank 70, It may be transferred to the tank 30 or transferred to the front end of the denitrifying tank 30. The operation method of the wastewater treatment apparatus according to the present embodiment is suitably applied to the wastewater treatment in which the nitrogen concentration wastewater, in which the methanol concentration is fluctuated in an irregular amount, is continuously treated with anaerobic ammonia bacteria.

[First Embodiment]

First, the configuration of a wastewater treatment apparatus (wastewater treatment apparatus according to the first embodiment) to which the operation method related to the first embodiment is applied will be described.

Fig. 2 is a view showing a schematic structure of a wastewater treatment apparatus to which an operation method related to the first embodiment is applied.

The wastewater treatment apparatus 1 according to the first embodiment is an apparatus for continuously treating nitrogen wastewater containing ammonia nitrogen with anaerobic ammonia oxidizing bacteria and is a treatment vessel using an anaerobic ammonia oxidation reaction, And is a two-piece wastewater treatment apparatus having a denitrification tank. 2, the wastewater treatment apparatus 1 mainly includes an adjusting tank 10, a methanol concentration measuring means 11, concentration reducing means 12a and 12b, a control device 16, a nitrification tank 20, and a denitrification tank 30. In addition, the scale of the wastewater treatment apparatus is not particularly limited, and includes a movable apparatus that is not settled on the land, or an apparatus composed of a scale corresponding to the wastewater treatment facility. In addition, in the construction of the wastewater treatment apparatus, other treatment vessels other than those shown in Fig. 1 and other vessels may be provided at the front end, the middle end, or the rear end.

In the waste water treatment apparatus 1, nitrogen waste water to be treated is introduced from a waste water supply source (not shown). Examples of the wastewater supply source include a storage tank for temporarily storing wastewater, a heterotrophic denitrification tank using heterotrophic denitrifying bacteria, a sulfur denitrification tank using sulfur oxidative denitrifying bacteria, and various other organic substances, sulfides, phosphorus, and the like And a treatment tank.

A pipeline drawn into the wastewater treatment apparatus 1 from a wastewater supply source (not shown) is connected to the adjustment tank 10. [ In this pipe, for example, a waste water supply pump (not shown) and a flow rate measuring means are provided.

The wastewater supply pump is an electromagnetic drive type pump, a motor drive type pump, and the like, which are provided for supplying nitrogen wastewater to the adjustment tank 10. The discharge amount of the wastewater supply pump is variably controlled based on the input of the control amount from the control device 16 so that the nitrogen wastewater sent from the wastewater supply source can be supplied to the adjustment tank 10 at a certain flow rate.

The flow rate measuring means is a measuring instrument or the like for measuring the flow rate of the nitrogen-containing wastewater supplied to the adjustment tank 10. As the flow rate measuring means, for example, a potential measuring flow meter, a differential pressure measuring flow meter, a mass flow meter, or the like can be used. The flow rate measuring means measures the quantity of nitrogen wastewater sent to the adjustment tank 10 and outputs the measurement signal to the control device 16.

The adjustment tank 10 is a treatment tank for adjusting in advance the concentration of methanol in the nitrogen-containing waste water introduced into the treatment tank at the downstream stage. 2, in the wastewater treatment apparatus 1, the adjustment tank 10 is provided at the front end of the denitrification tank 30 and at the front end of the nitrification tank 20, and immediately before the denitrification tank 30 Is simplified. The preparation 10 of this tank is mainly provided with methanol concentration measuring means 11, concentration reducing means 12a and 12b, stirring means 13, and the like.

The methanol concentration measuring means 11 is a measuring instrument for quantitatively determining the concentration of methanol in the nitrogen-containing wastewater. The methanol concentration measuring means 11 may be, for example, a gas chromatograph mass spectrometer. In addition, a total organic carbon (TOC) measuring instrument and a volatile organic compound (VOC) measuring instrument can be used. These measuring devices can be used in a fixed amount of methanol concentration with respect to nitrogen-containing wastewater which does not substantially contain volatile components or other organic components other than methanol. The methanol concentration measuring means 11 measures the methanol concentration (or the organic substance concentration substantially corresponding to the methanol concentration) of the nitrogen-containing wastewater in the adjusting tank 10 in accordance with the sampling period of the predetermined time interval, And outputs a signal to the control device 16. The methanol concentration measuring means may also be provided in front of the adjusting tank 10 so that the inlet concentration of the adjusting tank 10 is measured.

The concentration reducing means is an apparatus for lowering the concentration of methanol contained in the nitrogen-containing wastewater. In the wastewater treatment device 1, the concentration lowering means is activated to prevent the exposure of the high concentration of methanol to the anaerobic ammonium oxidizing bacteria. As shown in Fig. 2, for example, the concentration reducing means is constituted by a dilution water storage tank 12a for supplying diluted water to nitrogen-containing wastewater and a dilution water supply pump 12b.

The dilute water storage tank 12a is a container for temporary storage of diluted water for diluting nitrogen-containing waste water. As the diluted water, for example, tap water containing no methanol, industrial water, industrial water, nitrogen wastewater, and treated water after the organic material treatment are used. The diluted water transferred from the water supply pipe, the industrial water supply pipe, and the water storage tank to the dilution water storage tank 12a is temporarily stored in the diluted water storage tank 12a. When the concentration adjustment process is performed, 10, thereby lowering the methanol concentration of the wastewater in the adjustment tank 10.

The diluting water supply pump 12b is an electronically driven pump, a motor driven pump, or the like, which is provided to supply the dilution water to the adjustment tank 10. The dilution water supply pump 12b is provided in a channel connecting the dilution water storage tank 12a and the adjustment tank 10. [ The discharge amount of the dilution water supply pump 12b is set such that the amount of dilution water stored in the dilution water storage tank 12a can be supplied to the adjustment tank 10 at an arbitrary flow rate by inputting a control amount from the control device 16 As shown in Fig. Instead of the diluting water supply pump 12b, a flow regulating valve for supplying the diluted pressurized water at a constant flow rate may be used.

The agitating means 13 is an apparatus for homogenizing the nitrogen-containing wastewater staying in the adjusting tank 10 by stirring. The agitation means 13 may be any of a mechanical type by cyclic motion of a stirring blade, a water flow type by sucking and discharging nitrogenous wastewater, and an air flow type by gas injection. By providing the stirring means 13, the distribution of the methanol concentration of the nitrogen-containing waste water staying in the adjustment tank 10 can be made uniform.

The control device 16 is a device for performing the operation management of the wastewater treatment device 1 and particularly has a function of controlling the concentration adjustment process for adjusting the methanol concentration of the nitrogen removal wastewater. The control device 16 includes, for example, a display section for visually displaying various measured values such as an operation input section for setting an upper limit value or a target value of the methanol concentration of the nitrogen-containing wastewater, a methanol concentration of the nitrogen-containing wastewater, An output section for outputting a control signal to the concentration reducing means, a storage section for storing an upper limit value, a target value, various measured values, and the like, and an operation section for calculating a control input amount to the concentration lowering means . Further, as shown in Fig. 2, the methanol concentration measuring means 11 and the dilution water supply pump 12b are electrically connected to each other through a signal line. There is also a function of outputting a control signal to a wastewater supply pump or the like and a function of calculating a control input amount to a wastewater supply pump or the like.

The nitrification tank 20 is a microorganism treatment tank that performs a nitrite type oxidation reaction using ammonia as a substrate using nitrite type oxidizing bacteria. In the nitrite type oxidation reaction, a part of the ammonia nitrogen contained in the nitrogen wastewater is partially oxidized to the nitrite nitrogen, and the composition of the nitrogen wastewater supplied to the subsequent anaerobic ammonia oxidation reaction is changed to ammonia nitrogen and nitrite nitrogen Is included in a predetermined ratio range. The nitrite type oxidation reaction is represented by the following reaction formula (2).

NH ₄ ⁺ + 3 / 2O ₂ ^- > NO ₂ ^- + 2H ⁺ + H ₂ O (2)

In the nitrification tank 20, nitrite type oxidizing bacteria are retained. The nitrite type oxidizing bacteria are bacteria which undergo nitrite type oxidation reaction under aerobic conditions and generate nitrite ions using ammonia ion as a substrate. Specific examples of such bacteria include bacteria belonging to the genus Nitrobacter, the genus Nitrospina, the genus Nitrococcus, the genus Nitrospira, and the like.

It is preferable that the nitrite type oxidizing bacteria are retained in the microorganism treatment tank in the immobilized state. Examples of the form of immobilization include, for example, a microorganism-adhered carrier for immobilizing bacteria by attaching the microorganism to the surface of the carrier, and a collective immobilization carrier for immobilizing bacteria by immobilizing bacteria in the carrier.

Examples of the carrier include a gel carrier such as polyvinyl alcohol, alginic acid, polyethylene glycol and acrylamide, a plastic carrier such as cellulose, polyester, polypropylene, vinyl chloride and polyurethane, and a carrier such as activated carbon, diatomaceous earth and zeolite Inorganic carriers and the like. The carrier may be in the form of a fluidized bed, a sponge, a nonwoven, or a hollow form using a floating carrier formed into a suitable shape such as a sphere, a cylinder, a cylinder, a cube, Filter material) in a honeycomb shape, a wavy shape, a lattice shape, a fiber shape, a chrysanthemum shape, or the like. With respect to the fluidized bed, the size of the floating carrier is preferably in the range of 1 mm or more and 10 mm or less, and the filling rate is preferably in the range of 10 volume% or more and 40 volume% or less with respect to the treatment tank capacity. On the other hand, regarding the stationary phase, the filling rate is preferably in the range of 10 vol.% Or more and 50 vol.% Or less in terms of apparent occupation volume with respect to the treatment tank capacity, and the porosity thereof is preferably 80% or more. 2, the immobilizing microorganisms 25 in which the sludge containing the nitrite type oxidizing bacteria are carried on the floating support are held in the nitrification tank 20. [

The nitrification tank 20 is provided with aeration means 22 as shown in Fig. Further, a nitrogen component system, a dissolved oxygen system, a water temperature meter, a pH meter, a flow meter, and the like (not shown) are provided.

The nitrogen component system is an instrument for measuring the concentration of the nitrogen component contained in the nitrogen wastewater, such as a nitrocell system, an ammonia-nitrogen system, and a nitrite-nitrogen system. The total nitrogen concentration, the ammonia nitrogen concentration and the nitrite nitrogen concentration contained in the nitrogen wastewater are measured by the nitrogen component system. Then, the reaction rate (nitrification rate) of the nitrite type oxidation reaction is grasped based on at least one of the measured total nitrogen concentration, the ammonia nitrogen concentration, and the nitrite nitrogen concentration.

The aeration means 22 is an apparatus or the like for dissolving oxygen-containing gas such as air in the nitrogen-containing wastewater in the nitrification tank 20. As the aeration means 22, either an acid type or a stirring type may be used. By the aeration means 22 dissolving the oxygen gas in the nitrification tank 20, the nitrification tank 20 becomes an aerobic atmosphere. Further, the output of the aeration means is feedback-controlled based on the measured dissolved oxygen concentration and the nitrification rate, and the nitrification rate is adjusted within a predetermined range by adjusting the concentration of dissolved oxygen in the nitrification tank 20.

The denitrification tank 30 is a microorganism treatment tank that performs an anaerobic ammonia oxidation reaction using ammonia and nitrite as a substrate using anaerobic ammonium oxidizing bacteria. In the anaerobic ammonia oxidation reaction, the ammonia nitrogen contained in the nitrogen wastewater is converted into nitrogen gas by denitrifying nitrite nitrogen as a hydrogen acceptor. In addition, the anaerobic ammonia oxidation reaction is represented by the above reaction formula 1.

Anaerobic ammonia-oxidizing bacteria are retained in the denitrification tank (30). The anaerobic ammonium oxidizing bacteria are anaerobic ammonia oxidation reactions under anaerobic conditions and generate nitrogen gas using ammonia and nitrous acid as substrates. Such a bacterium can be obtained as a sludge microorganism group by collecting a sample from, for example, lake, river, soil, drainage sludge, ocean, and the like, and carrying out integrated culture using ammonia and nitrite as a substrate.

It is preferable that the anaerobic ammonium oxidizing bacteria are retained in the microorganism treatment tank in the immobilized state. Examples of the form of immobilization include, for example, a microorganism-bearing carrier for immobilizing and immobilizing bacteria on the surface of the carrier, a collective immobilization carrier for immobilizing bacteria by immersing bacteria in the carrier, and self-assembly in which bacteria are coagulated to form granules . The form, nature and condition of the carrier can be selected to be the same as for the above-mentioned nitrite type oxidizing bacteria. As the nucleus for forming the granules, the above carriers and other aggregated microorganisms can be used. 2, the immobilizing tank 30 holds the immobilizing microorganisms 35 in which sludge containing anaerobic ammonium oxidizing bacteria is carried on a floating support.

As shown in Fig. 2, the denitrifying tank 30 is provided with stirring means. Further, a nitrogen component system, a water temperature meter, a pH meter, a flow meter, and the like (not shown) are provided.

The nitrogen component system is an instrument for measuring the concentration of the nitrogen component contained in the nitrogenous waste water, such as an electrolytic system, an ammonia-nitrogen system, a nitrite-nitrogen system, and a nitrate-nitrogen system. The total nitrogen concentration, the ammonia nitrogen concentration, the nitrite nitrogen concentration, and the nitrate nitrogen concentration contained in the nitrogen wastewater are measured by the nitrogen component system. Based on the measured concentrations of these nitrogen components, the reaction rate (denitration rate) of the anaerobic ammonia oxidation reaction and the nitrogen removal rate through wastewater treatment are grasped.

The agitating means 33 is an apparatus for homogenizing the nitrogen-containing wastewater staying in the denitrification tank 30 by stirring. The stirring means 33 may be any of a water-jet type by suction and discharge of a mechanical type or nitrogen-containing wastewater by cyclic motion of a stirring blade, and a jet type by an oxygen-free gas jetting. By providing the agitating means 33, it is possible to maintain the level of the denitrification rate by stirring the nitrogen-containing wastewater staying in the denitrifying tank 30, irrespective of the aeration of the oxygen-containing gas.

A nitrate nitrogen treatment tank, a sludge recovery tank, and the like (not shown) are provided at the rear end of the denitrifying tank 30 as needed, and the treated water of the wastewater treatment device 1 is drained. The nitrate nitrogen treatment tank is composed of, for example, a microbial treatment tank for treating nitrate nitrogen to a nitrogen gas and treating it, and a chemical treatment tank having an ion exchange membrane, a reverse osmosis membrane, and an denitration catalyst. In addition, in the sludge recovery tank, sludge containing anaerobic ammonia-oxidizing bacteria and the like flowing out from the denitrification tank is separated and recovered.

Next, a method of operating the wastewater treatment apparatus according to the first embodiment will be described.

The operation method of the wastewater treatment apparatus according to the first embodiment is an operation method of the wastewater treatment apparatus 1 including the concentration reduction means 12a and 12b and the denitrification tank 30, 12b), the concentration adjustment process for lowering the methanol concentration of the nitrogen-containing wastewater is carried out. The concentration adjustment treatment is performed by lowering the methanol concentration of the nitrogenous waste water to 30 mg / L or less when the methanol concentration of the nitrogenous waste water introduced into the denitrifying tank 30 becomes a concentration exceeding 30 mg / L. The lowering of the methanol concentration is caused by diluting the nitrogen wastewater.

The methanol concentration of 30 mg / L is a critical concentration found by the present inventors in a continuous treatment apparatus for wastewater. In the continuous treatment apparatus, irreversible deterioration of the denitrification activity exhibited by the anaerobic ammonium oxidizing bacteria does not occur, Is the maximum allowable concentration of methanol that can be tolerated to maintain the level of. That is, in the continuous treatment apparatus, when the methanol concentration in the nitrogen-containing wastewater exceeds 30 mg / L (inhibitory concentration), the influence of inhibition by methanol appears, and the nitrogen removal rate in the wastewater treatment apparatus tends to decrease, In the case where the flow of the nitrogen-containing wastewater is continued, the nitrogen removal rate is further lowered. On the other hand, if the methanol concentration is 30 mg / L (inhibitory concentration) or less, the denitrification activity of bacterial group or sludge including anaerobic ammonium oxidizing bacteria is hardly deactivated, and the influence of inhibition by methanol is practically recognized It is confirmed that it is not.

In the method of operating the wastewater treatment apparatus according to the first embodiment, during the continuous treatment of the nitrogenous waste water, the methanol concentration of the nitrogenous waste water staying in the adjustment tank 10 is continuously measured, When the concentration of methanol exceeds 30 mg / L, the concentration is always adjusted by dilution. This concentration adjustment process reduces the concentration of methanol in the nitrogen-containing wastewater that remains in the adjustment tank 10 to at least 30 mg / L or less, whereby the nitrogen-containing wastewater discharged from the adjustment tank 10 and introduced into the denitration tank 30 The concentration of methanol in the denitrification tank 30 is maintained at 30 mg / L or less at all times, and the exposure of the methanol exceeding the inhibitory concentration to the anaerobic ammonium oxidizing bacteria maintained in the denitrification tank 30 is prevented.

In the control device 16 provided in the wastewater treatment apparatus 1 according to the first embodiment, the upper limit value of the methanol concentration is set in advance by the operator's input. The upper limit value means the maximum allowable value of the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 directly. For example, when the start-up operation is started, the influx of methanol And is set in advance. In the wastewater treatment apparatus, the methanol concentration in the nitrification tank 20 at the rear stage of the adjustment tank 10 is not substantially increased, and the nitrogen concentration wastewater of the methanol concentration exceeding the maximum allowable concentration, (30). Therefore, by limiting the methanol concentration in the adjustment tank 10, the methanol concentration of the nitrogen-containing wastewater introduced into the denitrifying tank 30 is indirectly limited.

Concretely, the upper limit value of the methanol concentration is set to an arbitrary concentration at which the methanol concentration is 30 mg / L or less, preferably at 0.5 mg / L or more and 30 mg / L or less, more preferably 30 mg / . As a result, when the concentration of methanol in the nitrogen-containing wastewater exceeds 30 mg / L, concentration adjustment by dilution is always performed, and the concentration of methanol in the nitrogen-containing wastewater is reduced to 30 mg / L or less. When the concentration is in the range of 0.5 mg / L to 30 mg / L, nitrogen-containing wastewater containing a certain amount of methanol is introduced into the denitrifying tank 30, and as described later, the anaerobic ammonia- Can be imparted with methanol non-sensitivity on the surface. In particular, when the upper limit value is set to 30 mg / L, the concentration adjustment process for diluting the nitrogen component concentration contained in the nitrogen-containing wastewater is minimized.

In the wastewater treatment device 1 in which the upper limit value of the methanol concentration is set, the nitrogen-containing wastewater which may contain methanol is introduced from the wastewater supply source. The nitrogen-containing wastewater is sent to the adjustment tank 10 at a predetermined flow rate by the wastewater supply pump while measuring the flow rate by the flow rate measurement means, for example, so that the concentration of the nitrogen component flowing into the adjustment tank 10 gradually increases Management. By controlling introduction into the adjustment tank 10, the microorganisms retained in each treatment tank are acclimatized with respect to the nitrogen component, and the rapid introduction of methanol into the denitrification tank 30 is also prevented.

In the adjustment tank 10, the methanol concentration measurement means 11 measures the methanol concentration of the nitrogen-containing wastewater. The methanol concentration measuring means 11 measures the methanol concentration of the nitrogenous wastewater staying in the adjustment tank 10 in accordance with the sampling period at predetermined time intervals and outputs the measured methanol concentration measurement signal to the control device 16 do. The concentration of methanol to be measured is not necessarily limited to the concentration of methanol itself. When the nitrogen-containing wastewater contains substantially no other organic component or volatile component, the concentration of methanol is preferably set to a total organic concentration , Concentration of organic substances in the volatile component, and the like.

When the methanol concentration measuring means 11 receives the measurement signal of the methanol concentration, the control device 16 compares the measured value of the methanol concentration with the upper limit value of the methanol concentration set in advance and measures the methanol concentration When the value exceeds the upper limit value, concentration adjustment processing by dilution is performed. Namely, based on the deviation between the measured value and the upper limit value, the control amount of the dilution water supply pump 12b is calculated, and the control signal of the calculated control amount is outputted to the dilution water supply pump 12b. The dilution water supply pump 12b which receives the input of the control signal changes the discharge amount of the dilution water in a positive operation based on the control amount calculated by the control device 16, Is supplied to the adjustment tank (10) at a predetermined flow rate.

In the concentration adjustment process, the quantity of nitrogen wastewater sent to the adjustment tank 10 is adjusted, together with the adjustment of the supply amount of the dilution water, based on the measured value of the quantity of nitrogen wastewater measured by a flow rate measuring means You can. The outlet flow rate of the adjustment tank 10 is obtained on the basis of the supply amount of the dilution water to be supplied to the adjustment tank 10 and the latest value of the flow rate value of the nitrogen oxide waste water stored in the control device 16, Accordingly, the amount of the nitrogen-containing wastewater to be transferred to the adjustment tank 10 can be adjusted and the supply amount of the diluting water can be set. Thus, it is possible to prevent the occurrence of overflow due to the supply of a large amount of dilution water. The concentration adjustment processing may be based on the integral value of the concentration displacement between predetermined measurement intervals or may be performed by a method of controlling the valve opening degree of the concentration reduction means by time division. The control amount of the feedforward control is calculated on the basis of the measured value measured by the other methanol concentration measuring means provided at the front end of the adjusting tank 10 and the control amount is corrected to the measured value measured by the methanol concentration measuring means 11 . The parameters of these controls are obtained, for example, in the previous test set under the same process conditions.

On the other hand, the control device 16 compares the measured value of the methanol concentration with the upper limit value of the predetermined methanol concentration, and when the measured value of the methanol concentration is equal to or less than the upper limit value, the concentration adjusting process by dilution is not performed. In this case, the diluted water supply pump 12b maintains the full closed state, and the supply of the nitrogen-containing wastewater to the adjustment tank is continuously performed by the wastewater supply pump, and the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 There is substantially no case where the dilution water is supplied to the adjustment tank 10 until the dilution water is again increased.

In this way, in the adjustment tank 10, the feedback control of the operation of the dilution water feed pump 12b is carried out in accordance with the fluctuation of the methanol concentration of the nitrogen-containing wastewater that is staying, Is lowered to at least 30 mg / L or less. Thereafter, the nitrogen-containing wastewater is sequentially introduced into the nitrification tank 20 and the denitrification tank 30.

In the nitrification tank 20, the microbial treatment is performed using the nitrite type oxidation reaction with the nitrite oxidizing bacteria. Concretely, the microbial treatment in the nitrification tank 20 is carried out by adjusting the pH of the nitrogen-containing wastewater to about pH 6.0 to 8.5 or less and adjusting the water temperature to about 10 to 40 ° C. In addition, in the nitrite type oxidation reaction, since the alkali is reduced by the consumption of ammonia nitrogen, alkali such as sodium hydroxide, sodium carbonate, sodium hydrogencarbonate or calcium carbonate is supplied if necessary.

In the nitrification tank, the total nitrogen concentration, the ammonia nitrogen concentration, the nitrite nitrogen concentration, and the like of the nitrogenous waste water are measured. By measuring these nitrogen component concentrations and calculating the ratio of ammonia nitrogen concentration or nitrite nitrogen concentration to total nitrogen concentration, the reaction rate (nitrification rate) of the nitrite type oxidation reaction can be confirmed.

The progress of the nitrite type oxidation reaction can be confirmed by oxidizing a part of the ammonia nitrogen contained in the nitrogen wastewater to nitrous acid by the ratio of ammonia nitrogen and nitrite nitrogen in the nitrogen wastewater, (1.00: 1.32) of ammonia nitrogen and nitrite nitrogen, that is, the nitrification rate is about 57%. The ratio of ammonia nitrogen and nitrite nitrogen can be adjusted mainly by increasing or decreasing dissolved oxygen concentration or pH. Further, the nitrogen-containing wastewater is distributed at a predetermined ratio at the upper end of the nitrification tank 20, a part of the nitrogen-containing wastewater is introduced into the nitrification tank 20 to treat the microorganisms with a predetermined nitrification ratio, , Or by bypassing them and then re-mixing them.

In the denitrification tank (30), microbial treatment is performed using the anaerobic ammonia oxidation reaction with the anaerobic ammonium oxidizing bacteria. Specifically, the microbial treatment in the denitrification tank 30 is carried out by adjusting the pH of the nitrogen-containing wastewater to about pH 6.0 to 8.5 or less and adjusting the water temperature to about 10 ° C to 40 ° C or so. In the anaerobic ammonia oxidation reaction, an acid such as sulfuric acid or hydrochloric acid is supplied as necessary in order to consume hydrogen ions.

In the denitrification tank 30, the total nitrogen concentration, ammonia nitrogen concentration, nitrite nitrogen concentration, nitrate nitrogen concentration, and the like of the nitrogenous waste water are measured. The rate of reaction (denitrification rate) of the anaerobic ammonia oxidation reaction can be confirmed by measuring the concentration of these nitrogen components and calculating the ratio of the ammonia nitrogen concentration, the nitrite nitrogen concentration or the nitrate nitrogen concentration from the nitrification tank 20 have. In addition, the nitrogen removal rate through wastewater treatment can be confirmed by matching with the measurement results of the front end.

The progress of the anaerobic ammonia oxidation reaction in the denitrification tank 30 is preferably controlled such that the outlet concentration of the nitrite nitrogen in the denitrification tank 30 which inhibits the anaerobic ammonia oxidation reaction is lower than a predetermined concentration Do. Thereafter, the treated water treated in the denitrification tank 30 is supplied to nitrate nitrogen treatment, if necessary, and then drained to the outside of the wastewater treatment apparatus 1. [ The nitrate nitrogen treatment can be carried out, for example, in a chemical treatment tank including a microbial treatment tank for reducing nitrate nitrogen to nitrogen gas, and an ion exchange membrane, reverse osmosis membrane, denitration catalyst and the like.

In this manner, the nitrogen-containing wastewater which is sequentially introduced into the adjustment tank 10, the nitrification tank 20, and the denitrification tank 30 is subjected to the continuous treatment while the concentration adjustment process of lowering the methanol concentration to at least 30 mg / It goes. In the wastewater treatment apparatus 1, when the nitrification rate, the denitration rate and the nitrogen removal rate with respect to the nitrogen load are stabilized, the nitrogen component concentration of the nitrogen-containing wastewater introduced into the wastewater treatment apparatus 1 is increased stepwise, Even in the normal operation in which the load has been reached, the operation is performed so that the concentration adjustment process is performed only when the concentration of methanol in the nitrogen-containing wastewater exceeds the upper limit value.

According to the operation method of the wastewater treatment apparatus according to the first embodiment described above, the concentration lowering means 12a and 12b provided at the front end of the denitrifying tank 30 can reduce the methanol concentration of the nitrogenous effluent water introduced into the denitrification tank 30 The concentration of methanol in the nitrogen-containing wastewater is always 30 mg / L or less. Therefore, the concentration of the nitrogen-containing wastewater is diluted so that the anaerobic ammonia oxidation The bacteria are not exposed to methanol having a concentration exceeding 30 mg / L, so that deterioration of the denitrification activity of the anaerobic ammonium oxidizing bacteria is prevented. Therefore, the nitrogen-containing wastewater containing methanol can be stably denitrified while maintaining the denitration activity of the anaerobic ammonium oxidizing bacteria at a high level. In addition, since the denitrification can be performed stably regardless of the methanol concentration of the nitrogen-containing wastewater to be introduced into the wastewater treatment apparatus 1, an organic matter treatment tank such as a re-aeration tank or the like is provided in front of the denitrification tank 30, There is an advantage that it is not necessary to operate the organic substance treatment tank so as to completely decompose the methanol contained in the wastewater. Further, when the heterotrophic denitrifying tank or heterotrophic denitrification tank using the heterotrophic bacteria is disposed at the front end of the denitrifying tank 30, it is advantageous that there is no need to limit the addition of methanol to them.

[Second Embodiment]

Next, the configuration of a wastewater treatment apparatus (wastewater treatment apparatus according to the second embodiment) to which the operation method related to the second embodiment is applied will be described.

Fig. 3 is a diagram showing an example of a schematic configuration of a wastewater treatment apparatus to which an operation method according to the second embodiment is applied.

The wastewater treatment apparatus 2 according to the second embodiment is similar to the wastewater treatment apparatus 1 according to the first embodiment in that the nitrogen wastewater containing ammonia nitrogen is continuously treated with anaerobic ammonia oxidizing bacteria And is a two-piece wastewater treatment apparatus having at least a nitrification tank and a denitrification tank as a treatment tank using an anaerobic ammonia oxidation reaction. The wastewater treatment apparatus 2 according to the second embodiment differs from the wastewater treatment apparatus 1 according to the first embodiment in that methanol capable of inhibiting the activity of the anaerobic ammonium bacteria is treated with nitrogen And methanol supply means for aggressively supplying the wastewater to the wastewater. 3, the wastewater treatment apparatus 2 mainly includes an adjustment tank 10, concentration reducing means 12a and 12b, methanol supply means 18a and 18b, a control device 16, A nitrification tank 20, and a denitrification tank 30.

The methanol supplying means is a device for increasing the concentration of methanol contained in the nitrogen wastewater by supplying methanol to the nitrogen wastewater. In the wastewater treatment device (2), the methanol supply means is activated during the start-up operation, so that the anaerobic ammonium-oxidizing bacteria are washed away from the nitrogen-containing wastewater containing methanol. As shown in Fig. 3, the methanol supply means is constituted by a methanol storage tank 18a for supplying methanol to the nitrogen-containing waste water and a methanol feed pump 18b.

The methanol storage tank 18a is a container for temporarily storing methanol supplied to the nitrogen-containing waste water. As the methanol, for example, a solution previously diluted with tap water, industrial water, nitrogen-containing wastewater or the like to a predetermined concentration may be used. Methanol temporarily stored in the methanol storage tank 18a is supplied to the adjustment tank 10 by the methanol supply pump 18b to increase the methanol concentration of the wastewater in the adjustment tank 10 when the concentration adjustment process is performed.

The methanol feed pump 18b is an electromagnetic driven pump, a motor driven pump, or the like, which is provided for supplying methanol to the adjustment tank 10. [ The methanol supply pump 18b is provided in a channel connecting the methanol storage tank 18a and the adjustment tank 10. [ The discharge amount of the methanol feed pump 18b is determined based on the input of the control amount from the controller 16 so that the methanol stored in the methanol storage tank 18a can be pumped to the adjustment tank 10 at a predetermined flow rate So as to be variably controlled. Instead of the methanol feed pump 18b, a flow rate adjusting valve for adjusting the amount of pressurized methanol to a constant amount may be used.

In the wastewater treatment apparatus 2 according to the second embodiment, by providing such methanol supply means 18a and 18b, nitrogen-containing wastewater containing substantially no methanol concentration or nitrogen- Methanol can be positively supplied. That is, the nitrogen-containing wastewater having an average concentration of methanol at a low level (for example, 0.5 mg / L or less) or a concentration of methanol is irregular and does not fluctuate by a fixed amount It is possible to use stable nitrogen purge wastewater for the concentration adjustment treatment.

The control device 16 is further provided with an output section for outputting a control signal to the methanol supply means and an operation section for calculating the control input amount to the methanol supply means in the wastewater treatment apparatus 2. Further, as shown in Fig. 3, the methanol concentration measuring means 11 and the methanol supplying means 18b are electrically connected to each other through a signal line.

Next, a method of operating the wastewater treatment apparatus according to the second embodiment will be described.

The operation method of the wastewater treatment apparatus according to the second embodiment is an operation method of the wastewater treatment apparatus 2 including the above methanol supply means 18a and 18b and the denitrification tank 30 and the methanol supply means 18a, 18b), the concentration adjustment process for increasing the methanol concentration of the nitrogen-containing wastewater to a predetermined concentration is carried out. The concentration adjustment treatment is performed by supplying methanol to the nitrogen-containing wastewater so that the methanol concentration of the nitrogen-containing wastewater fed into the denitrifying tank 30 is 0.5 mg / L or more and 30 mg / L or less.

The supply of methanol, which inhibits the activity of anaerobic ammonia-oxidizing bacteria, to the nitrogen-containing wastewater is advantageous in that the anaerobic ammonia-oxidizing bacteria are exposed to methanol with an inhibitory concentration (30 mg / L) It is based on the knowledge gained by the inventors. In the continuous treatment apparatus, if the methanol concentration of the nitrogen-containing wastewater flowing into the denitrifying tank 30 is equal to or lower than the inhibiting concentration, irreversible deterioration of the denitrification activity does not occur, and the influx of the nitrogen- It was confirmed that even when methanol having a concentration exceeding the inhibition concentration was introduced into the denitrifying tank 30, the decrease in the denitration activity was reduced. Namely, the nitrogen-containing wastewater containing methanol was introduced into the denitrifying tank 30 in a concentration range of 0.5 mg / L or more and 30 mg / L or less under a flow rate of a normal nitrogen load, whereby the methanol- It is intended that the anaerobic ammonia-oxidizing bacteria are provided with surface insensitivity to methanol.

In the method of operating the wastewater treatment apparatus according to the second embodiment, the concentration of methanol in the nitrogen-containing wastewater staying in the adjustment tank 10 is 0.5 mg / L or more and 30 mg / L or less when the wastewater treatment apparatus 2 is started The concentration adjusting process for supplying methanol to the nitrogen-containing wastewater is performed so as to have a predetermined concentration. By maintaining the concentration of methanol in the nitrogen-containing wastewater staying in the adjustment tank 10 within the range of 0.5 mg / L or more and 30 mg / L or less, the nitrogen-containing wastewater containing methanol at the inhibition concentration or lower Is introduced into the denitrification tank (30) from the regeneration tank (10) over a predetermined period of time, and an amorphous amount of anaerobic ammonia - oxidizing bacteria against the methanol in the nitrogenous wastewater below the inhibitory concentration is purified.

In the control device 16 provided in the wastewater treatment device 2 according to the second embodiment, the target value of the methanol concentration is set in advance by the operator's input. The target value means a control target value of the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10, and is set in advance at the start of the starting operation, for example. Methanol is not supplied to the nitrification tank 20 at the rear stage of the adjustment tank 10 and the amount of methanol deaeration by the aeration means 22 is also small in the wastewater treatment device 2 so that the methanol concentration is substantially increased or decreased substantially It does not. Therefore, by adjusting the methanol concentration in the adjustment tank 10, the methanol concentration of the nitrogen-containing wastewater introduced into the denitrifying tank 30 is indirectly adjusted.

As the target value of the methanol concentration, specifically, an arbitrary concentration at which the methanol concentration is 0.5 mg / L or more and 30 mg / L or less can be set. However, the higher the concentration in this concentration range, the shorter the period of the incubation of the anaerobic ammonium oxidizing bacteria. Therefore, it is preferable that the concentration is in the range of 1 mg / L to 30 mg / L or 20 mg / L to 30 mg / L Set the concentration.

In the wastewater treatment apparatus in which the target value of the methanol concentration is set, the nitrogen-containing wastewater is introduced from the wastewater supply source. The nitrogen-containing wastewater is introduced into the regeneration tank at a predetermined flow rate, for example, by measuring the flow rate by the flow rate measuring means, and introducing the nitrogen-containing wastewater while gradually controlling the concentration of the nitrogen component introduced into the regeneration tank. As the nitrogenous wastewater to be introduced during the start-up operation, wastewater containing substantially no methanol and wastewater having a methanol concentration of 0.5 mg / L or less are preferable, and the concentration of methanol is irregularly fluctuated And wastewater which is stable at a predetermined concentration is preferable. The target value is set so as to exceed the methanol concentration of such nitrogen wastewater.

In the adjusting tank 10, the methanol concentration measuring means 11 measures the methanol concentration of the introduced nitrogen wastewater. The methanol concentration measuring means 11 measures the methanol concentration of the nitrogenous wastewater staying in the adjustment tank 10 in accordance with the sampling period at predetermined time intervals and outputs the measured methanol concentration measurement signal to the control device 16 do. Also, as in the waste water treatment apparatus 1, the methanol concentration to be measured is not necessarily limited to the concentration of methanol itself.

When receiving the measurement signal of the methanol concentration output from the methanol concentration measurement means 11, the control device 16 compares the measured value of the methanol concentration with a predetermined target value of the methanol concentration, When the measured value is equal to or lower than the target value, concentration adjustment processing by supplying methanol is performed. That is, the control amount of the methanol feed pump 18b is calculated based on the deviation between the measured value and the target value, and the control signal of the calculated control amount is output to the methanol feed pump 18b. The methanol feed pump 18b that receives the input of the control signal changes the amount of methanol discharged by the forward operation based on the control amount computed by the controller 16 and feeds the methanol stored in the methanol storage tank 18a And supplied to the adjustment tank 10 at a predetermined flow rate. The concentration adjustment processing may be performed by a method of controlling the valve opening degree of the methanol supply means by time division or the like.

On the other hand, the control device 16 compares the measured value of the methanol concentration with the target value of the previously set methanol concentration, and when the measured value of the methanol concentration exceeds the target value, . In this case, the methanol feed pump 18b is kept in a fully closed state, and the wastewater supply pump continuously supplies the nitrogen wastewater to the adjustment tank 10, and the methanol of the nitrogen wastewater staying in the adjustment tank 10 The supply of methanol is stopped until the concentration is lowered.

Thus, in the adjustment tank 10, the methanol concentration of the nitrogen-containing wastewater to be introduced into the denitrifying tank 30 at the subsequent stage is controlled by feedback control of the operation of the methanol feed pump 18b in accordance with the methanol concentration of the nitrogen- To a predetermined concentration of 0.5 mg / L or more and 30 mg / L or less. Thereafter, the nitrogen-containing wastewater is sequentially introduced into the nitrification tank 20 and the denitrification tank 30.

In the operation method according to the second embodiment, in the nitrification tank and the denitrification tank, the microorganism treatment is performed under the condition similar to that of the wastewater treatment apparatus related to the first embodiment. Since the methanol concentration of the nitrogen-containing wastewater introduced into the denitrifying tank 30 is maintained at a predetermined concentration of 0.5 mg / L or more and 30 mg / L or less by performing the above concentration adjustment processing in the starting operation, the denitrification tank 30 ), The denitrification activity is not deteriorated, and the nitrate wastewater containing a certain concentration of methanol at the inhibiting concentration or less is washed away. When it is difficult to maintain the concentration of methanol in the adjustment tank 10 at 30 mg / L or lower only by supplying the nitrogen-containing wastewater to the adjustment tank 10 by the wastewater supply pump while the anaerobic ammonia-oxidizing bacteria are being flushed, The concentration adjusting process by dilution may be performed by the concentration reducing means 12a and 12b.

When the nitrogen-containing wastewater containing methanol is introduced into the denitrification tank 30 in which the amorous amount of the anaerobic ammonia-oxidizing bacteria is maintained in the concentration range of 0.5 mg / L to 30 mg / L over a predetermined period, The oxidizing bacterium becomes homologous to methanol on the surface and becomes methanol-insensitive. Therefore, when the denitrification rate does not decrease in response to the increase of the methanol concentration after the initiation of the continuous introduction of the methanol-containing nitrogen wastewater and the microbial treatment for a predetermined period of time, It is possible to end the execution of the concentration adjustment process.

In the starting operation, when the nitrogen component concentration of the introduced nitrogen wastewater is increased stepwise and the reaction rate of each treatment tank is stabilized, normal operation is performed under a nitrogen load in a predetermined range. In the normal operation, the target value set in the concentration range of 0.5 mg / L to 30 mg / L can be maintained, but the upper limit value of the methanol concentration can be reset by the operator's input in the same manner as the wastewater treatment device 1 . Specifically, as the upper limit value in the normal operation, an arbitrary concentration at which the methanol concentration is 30 mg / L or more, and preferably 30 mg / L or more and 200 mg / L or less can be set. Thus, in the case where the methanol concentration of the nitrogen-containing wastewater continuously treated varies to a concentration exceeding the upper limit value, concentration adjustment by dilution is carried out, so that the concentration of methanol introduced into the denitration tank 30 becomes excessive .

According to the operation method of the wastewater treatment apparatus according to the second embodiment as described above, the methanol supply means 18a and 18b provided at the front end of the denitrification tank 30 can control the methanol concentration of the nitrogen wastewater introduced into the denitrification tank 30 Of the anaerobic ammonia-oxidizing bacteria maintained in the denitrification tank 30 is lower than 30 mg / L in methanol having a concentration exceeding 30 mg / L. It is not exposed and is carried out in nitrogen-containing wastewater containing methanol, and becomes surface-insensitive to methanol. Generally, anaerobic ammonia-oxidizing bacteria, which are known to have a long induction period of proliferation and a very low propagation rate, are allowed to flow in advance to methanol, and thereby nitrogen-containing wastewater which can fluctuate in methanol concentration in an irregular amount , It becomes possible to perform the denitration treatment stably while maintaining the denitration activity of the anaerobic ammonium oxidizing bacteria at a high level. Also, since the denitrification activity is not easily lowered even if the anaerobic ammonia oxidizing bacterium is exposed to higher nitrogen concentration nitrogen wastewater, the concentration of methanol in the wastewater wastewater introduced into the wastewater treatment apparatus fluctuates stably It becomes possible to continue the denitration treatment.

[Modifications]

Next, another embodiment (a wastewater treatment apparatus according to a modified example) of the wastewater treatment apparatus to which the operation method related to the above-described embodiment is applied will be described.

Fig. 4 is a diagram showing an example of a schematic configuration of a wastewater treatment apparatus according to a modification.

The wastewater treatment device 3 related to the modified example is a treatment tank for performing a biological treatment using the anaerobic ammonia oxidation reaction in the same manner as the wastewater treatment device 2 described above and is composed of at least two types of wastewater Processing apparatus. The wastewater treatment apparatus 3 according to the modified example is different from the wastewater treatment apparatus 2 in that the adjustment tank 10 in which the concentration adjustment process for adjusting the methanol concentration of the nitrogen- And the shear is also provided at the rear end of the nitrification tank 20.

Like the wastewater treatment device 2 described above, the adjustment tank 10 is a treatment tank for previously adjusting the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank 30 at the downstream stage. 4, the adjustment tank 10 is mainly provided with a methanol concentration measuring means 11, concentration reducing means 12a and 12b, stirring means 13, methanol supplying means 18a and 18b, and the like .

The operation method of the wastewater treatment device 3 according to the modified example is performed in accordance with the wastewater treatment devices 1 and 2 described above. That is, the concentration-decreasing means 12a and 12b perform dilution-concentration adjustment processing based on the measurement of the methanol concentration of the nitrogen-containing wastewater by the methanol concentration measuring means 11, The concentration of methanol in the nitrogen-containing wastewater staying in the adjustment tank 10 is adjusted to the lower limit value or the target value by performing the concentration adjustment processing by the supply of methanol. The same is true for the starting and normal operating methods.

According to the wastewater treatment apparatus 3 described above, the adjustment tank 10 for performing the concentration adjustment treatment is provided at the rear end of the nitrification tank 20 in front of the denitrification tank 30, The nitrogen-containing wastewater to which the above concentration adjustment treatment is not applied is provided. Therefore, the nitrogen load on the nitrification tank 20 is not varied by the supply of the diluting water, and the nitrite type oxidation reaction is stably maintained. In addition, the BOD of the nitrification tank 20 is not fluctuated by the supply of methanol to the nitrogen-containing wastewater, and the amount of the generated sludge is reduced, so that the nitrite type oxidation reaction can be easily stabilized.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention, but the technical scope of the present invention is not limited thereto.

First, the influence of methanol on the continuous treatment of nitrogenous waste water was evaluated in a continuous treatment test system.

The continuous treatment test was conducted by passing nitrogen-containing wastewater containing methanol through the reactor into which the anaerobic ammonia-oxidizing bacteria were added, and the concentration of methanol was adjusted to 5 mg / L, 20 mg / L, 30 mg / The test was carried out in total of 4 types.

In each test, the reaction volume of the reactor was adjusted to 0.5 L, and the agglomerated immobilized carrier in an agar state in which anaerobic ammonium oxidizing bacteria were carried was charged at a filling rate of 20 vol% per reaction volume. The test conditions were anaerobic conditions of a water temperature of 30 ° C and a pH of 7.6. During the continuous treatment, pH was maintained by addition of hydrochloric acid, and stirring was continued with a stirrer. In each test, the composition of the synthetic wastewater used as nitrogenous waste water is shown in Table 1 below.

[Example 1-1]

As Example 1-1, continuous treatment of nitrogen wastewater having a methanol concentration of 5 mg / L was carried out. In Example 1-1, the nitrogen volume load of the wastewater passing through the reactor was set to be 4.0 kg-N / m ³ / d, the nitrogen-containing wastewater without methanol was passed through the wastewater, Treatment. Then, at the stage where the nitrogen removal rate with respect to the load was stabilized, the flow of nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started and monitoring of the nitrogen removal rate was continued. The results are shown in Fig.

5 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Example 1-1.

In FIG. 5, the horizontal axis represents the processing time (days), the left axis represents the nitrogen volume load and the nitrogen removal rate, and the right axis represents the methanol concentration of nitrogenous waste water. As shown in Fig. 5, even when the flow of the nitrogen-containing wastewater having the methanol concentration of 5 mg / L was started, the nitrogen removal rate with respect to the nitrogen load was not reduced, and the nitrogen removal rate was maintained during the passage.

[Example 1-2]

As Example 1-2, continuous treatment of nitrogen dioxide wastewater with a methanol concentration of 20 mg / L was carried out. In Example 1-2, in the same manner as in Example 1-1, the nitrogen volume load of the wastewater passing through the reactor was set to 4.0 kg-N / m ³ / d, and in the state in which methanol was not added Nitrogen wastewater was passed through and treated for a predetermined period of time. Then, at the stage where the nitrogen removal rate with respect to the load was stabilized, the flow of nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started and monitoring of the nitrogen removal rate was continued. The results are shown in Fig.

6 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Example 1-2.

In Fig. 6, the horizontal axis represents the processing time (days), the left axis represents the nitrogen volume load and the nitrogen removal rate, and the right axis represents the methanol concentration of nitrogenous waste water. As shown in Fig. 6, even when the nitrogen-containing wastewater having a methanol concentration of 20 mg / L was passed through, the nitrogen removal rate with respect to the nitrogen load was not reduced, and the nitrogen removal rate was maintained during the passage of water.

[Example 1-3]

As Example 1-3, continuous treatment of nitrogen wastewater with a methanol concentration of 30 mg / L was carried out. In Example 1-3, in the same manner as in Example 1-1, the nitrogen volume load of the wastewater passing through the reactor was set to 4.0 kg-N / m ³ / d, and in the state where no methanol was added Nitrogen wastewater was passed through and treated for a predetermined period of time. Then, at the stage where the nitrogen removal rate with respect to the load was stabilized, the flow of nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started and monitoring of the nitrogen removal rate was continued. The results are shown in Fig.

7 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Examples 1-3.

In Fig. 7, the horizontal axis represents the processing time (days), the left axis represents the nitrogen volume load and the nitrogen removal rate, and the right axis represents the methanol concentration of nitrogenous waste water. As shown in Fig. 7, when the flow of the nitrogen-containing wastewater having the methanol concentration of 30 mg / L was started, the nitrogen removal rate with respect to the nitrogen load was slightly lowered and the nitrogen removal rate was 4.0 kg-N / m ³ / , Day and time, 3.56 kg-N / m ³ / d. However, after that, the nitrogen removal rate showed a slight recovery tendency, and after a few days, the nitrogen removal rate recovered by about 5% to about 3.81 kg-N / m ³ / d. Thereafter, the flow of the nitrogen-containing wastewater containing methanol was stopped, and the flow of the nitrogen-containing wastewater without methanol was continued. The nitrogen removal rate was about 3.81 kg-N / m ³ / d Respectively.

[Comparative Example 1]

As Comparative Example 1, continuous treatment of nitrogen-containing wastewater with a methanol concentration of 40 mg / L was carried out. In Comparative Example 1, in the same manner as in Example 1-1, the nitrogen volume load of the wastewater passing through the reactor was set to 4.0 kg-N / m ³ / d, and the nitrogen- And wastewater treatment was performed for a predetermined period. Then, at the stage where the nitrogen removal rate with respect to the load was stabilized, the flow of nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started and monitoring of the nitrogen removal rate was continued. The results are shown in Fig.

8 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Comparative Example 1. Fig.

In FIG. 8, the horizontal axis represents the processing time (days), the left axis represents the nitrogen volume load and the nitrogen removal rate, and the right axis represents the methanol concentration of nitrogenous waste water. 8, the methanol concentration of 40mg / L phosphorus when initiating a water flow of the nitrogen wastewater, nitrogen removal rate is rapidly decreased ^{and, 3.8kg-N / m 3 /} d was approximately nitrogen removal rate for the nitrogen load After 3 days, it showed a drop of about 60% up to 1.5 kg-N / m ³ / d. Thereafter, the flow of the nitrogen-containing wastewater containing methanol was stopped, and the flow of the nitrogen-containing wastewater without methanol was continued, but the recovery of the nitrogen removal rate was not recognized.

From these results, it can be seen that, even in the case where the nitrogenous wastewater containing a high concentration of methanol is suddenly introduced or the methanol concentration of the nitrogenous wastewater is suddenly changed to the high concentration side in the continuous treatment of the nitrogenous waste water, / L or less, the denitrification activity of the anaerobic ammonium oxidizing bacteria is not easily lowered. Therefore, it has been confirmed that the denitration activity is maintained at a relatively high level by keeping the methanol concentration within the range of 30 mg / L or less, and it is possible to stably denitrify the nitrogen-containing wastewater containing methanol.

Next, the acclimatization (acclimatization) of the anaerobic ammonia-oxidizing bacteria to the nitrogen-containing wastewater containing methanol was evaluated.

[Example 2-1]

As Example 2-1, continuous treatment of nitrogen wastewater was carried out while gradually increasing the methanol concentration to 5 mg / L. In Example 2-1, the nitrogen volume load of the wastewater passing through the reactor was set to 4.0 kg-N / m ³ / d. First, the nitrogen-containing wastewater to which no methanol was added was passed through the reactor The wastewater treatment was continued. Then, at a stage where the nitrogen removal rate with respect to the load is stabilized, a synthetic wastewater containing methanol is added so that the methanol concentration is 5 mg / L. Thereafter, at the stage where the nitrogen removal rate with respect to the load is stabilized, the operation of passing the synthetic wastewater having the methanol concentration increased to 5 mg / L unit is gradually repeated, and finally the nitrogen removal is carried out until the methanol concentration reaches 60 mg / I continued to monitor the speed. The results are shown in Fig.

9 is a graph showing the relationship between the methanol concentration and the nitrogen removal rate of the nitrogen-containing wastewater in Example 2-1.

In Fig. 9, the abscissa represents the processing time (days), the left axis represents the nitrogen volume load and the nitrogen removal rate, and the right axis represents the methanol concentration of nitrogenous waste water. As shown in Fig. 9, when the concentration of methanol in the nitrogen-containing wastewater was increased by 5 mg / L, the nitrogen removal rate was not reduced, and even when the methanol concentration exceeded 30 mg / L, the activity of the anaerobic ammonium- Was maintained at a high level. Further, even in the nitrogen-containing wastewater having a methanol concentration of 60 mg / L, the nitrogen removal rate was not lowered, and it was confirmed that the anaerobic ammonium-oxidizing bacteria were homogenized with respect to methanol.

[Example 2-2]

As Example 2-2, continuous treatment of nitrogen wastewater was carried out while increasing the concentration of methanol to a pulse shape so that the concentration of methanol was increased to a high concentration for a predetermined period and the change in methanol concentration gradually increased. In Example 2-2, the nitrogen volume load of the wastewater passing through the reactor was set to 4.0 kg-N / m ³ / d. First, the nitrogen-containing wastewater to which no methanol was added was passed through the reactor for a predetermined period Wastewater treatment was carried out. Then, at a stage where the nitrogen removal rate with respect to the load was stabilized, the synthetic wastewater having a methanol concentration of 30 mg / L was started to flow, and after a few days, the synthetic wastewater having a methanol concentration of 30 mg / L was stopped, And the water was converted into the feed water of nitrogen-free waste water. Thereafter, the same operation was repeated so that the methanol concentration was increased to 40 mg / L, 50 mg / L, 100 mg / L and 200 mg / L, and monitoring of the nitrogen removal rate was continued. The results are shown in Fig.

10 is a graph showing the relationship between the methanol concentration of the nitrogen-containing wastewater and the nitrogen removal rate in Example 2-2.

In Fig. 10, the abscissa represents the processing time (days), the left axis represents the nitrogen volume load and the nitrogen removal rate, and the right axis represents the methanol concentration of the nitrogen-containing wastewater. As shown in Fig. 10, the nitrogen removal rate with respect to the nitrogen load temporarily decreased slightly at the time when the flow of synthetic wastewater having a methanol concentration of 30 mg / L was started, as in Example 1-3, The nitrogen removal rate showed a tendency to recover. Thereafter, even when the methanol concentration was increased to 40 mg / L, 50 mg / L, 100 mg / L, and 200 mg / L in pulses, no reduction in the nitrogen removal rate with respect to the load was recognized, and the anaerobic ammonium- .

From these results, it can be concluded that if the anaerobic ammonia-oxidizing bacteria are harvested from the nitrogen wastewater having a methanol concentration of 30 mg / L or less, then the nitrogen wastewater containing methanol at a concentration exceeding 30 mg / L suddenly flows, The denitrification activity of the anaerobic ammonium oxidizing bacteria is maintained at a relatively high level without deteriorating even if the methanol concentration of the nitrogen wastewater is rapidly changed to the high concentration side exceeding 30 mg / L, and the nitrogen containing wastewater containing methanol It is possible to stably perform the denitration treatment.

The denitrification activity of the anaerobic ammonium oxidizing bacteria is maintained because the other microorganisms mixed in the wastewater reproduce around the anaerobic ammonia oxidizing bacteria to form a biofilm and these microorganisms decompose methanol, It is considered that the exposure of the high-concentration methanol is prevented. Therefore, it is preferable that the anaerobic ammonia-oxidizing bacteria are held in the denitrification tank 30 in a fixed state so as to be easily protected by the biofilm by other microorganisms.

1: Wastewater treatment device
10: Regulation tank
11: Means for measuring methanol concentration
12a: Dilution water storage tank (concentration reducing means)
12b: diluting water supply pump (concentration reducing means)
13: stirring means
16: Control device
18a: Methanol storage tank (Methanol supply means)
18b: methanol feed pump (methanol feed means)
20: nitrification tank
22: aeration means
25: Immobilized microorganism
30: Denitrification tank
33: stirring means
35: Immobilized microorganism
60: Organic material treatment tank
70: Dependent nutrient denitrification tank

Claims (6)

1. A method for operating a wastewater treatment apparatus for continuously treating nitrogen wastewater containing ammonia nitrogen by anaerobic ammonium oxidizing bacteria,
The wastewater treatment apparatus includes:
Concentration reducing means for reducing the methanol concentration of the nitrogen-containing waste water;
And an denitrifying tank for converting the ammonia nitrogen contained in the nitrogen wastewater and the nitrite nitrogen generated by oxidation of a part of the ammonia nitrogen into nitrogen gas by the anaerobic ammonium oxidizing bacteria,
Wherein the concentration lowering means reduces the methanol concentration of the nitrogen-containing wastewater to 30 mg / L or less when the concentration of methanol in the nitrogen-containing wastewater to be introduced into the denitrifying vessel becomes a concentration exceeding 30 mg / L. A method of operating a processing apparatus. The method according to claim 1,
Wherein the concentration lowering means reduces the methanol concentration of the nitrogen-containing wastewater to 0.5 mg / L or more and 30 mg / L or less when the methanol concentration of the nitrogen-containing wastewater to be introduced into the denitrification tank reaches a concentration exceeding 30 mg / L And the operation of the waste water treatment apparatus is performed. 1. A method for operating a wastewater treatment apparatus for continuously treating nitrogen wastewater containing ammonia nitrogen by anaerobic ammonium oxidizing bacteria,
The wastewater treatment apparatus includes:
Methanol supply means for supplying methanol to the nitrogen-containing wastewater,
And an denitrifying tank for converting the ammonia nitrogen contained in the nitrogen wastewater and the nitrite nitrogen generated by oxidation of a part of the ammonia nitrogen into nitrogen gas by the anaerobic ammonium oxidizing bacteria,
Wherein the methanol supply means supplies methanol to the nitrogen-containing wastewater so that the methanol concentration of the nitrogen-containing wastewater to be introduced into the denitrifying tank is 0.5 mg / L or more and 30 mg / L or less . The method of claim 3,
Wherein the nitrogen-containing wastewater to which the methanol is supplied is introduced into the denitrification tank in which an amorphous amount of anaerobic ammonium-oxidizing bacteria is retained in methanol. 5. The method of claim 4,
The wastewater treatment apparatus further comprises a concentration lowering means for lowering the methanol concentration of the nitrogen-
Wherein the concentration lowering means reduces the methanol concentration of the nitrogen-containing wastewater to 30 mg / L or less when the concentration of methanol in the nitrogen-containing wastewater to be introduced into the denitrifying vessel becomes a concentration exceeding 30 mg / L. A method of operating a processing apparatus. 6. The method according to any one of claims 1 to 5,
Wherein the anaerobic ammonium oxidizing bacteria are immobilized in at least one form selected from the group consisting of a microorganism-adhered carrier, a collective immobilization carrier, and a self-assembly.

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