KR20140063454A - Apparatus and method for treatment wastewater - Google Patents

Abstract

Provided is a means for rapidly performing and stably continuing a treatment using anaerobic ammonia oxidation which is performed in treating nitrogen-containing wastewater. The wastewater treatment method used herein includes: a nitrous acid type oxidation step for oxidizing a part of ammonia nitrogen contained in wastewater into nitrite nitrogen in the presence of anaerobic ammonia oxidation bacteria; a dilution water supply step for supplying the oxidized wastewater with dilution water which reduces at least one of the concentration of the nitrite nitrogen and the concentration of the dissolved oxygen in the wastewater; and a denitrification step for converting the ammonia nitrogen and the nitrite nitrogen contained in the oxidized wastewater to nitrogen gas in the presence of the anaerobic ammonia oxidation bacteria.

Description

TECHNICAL FIELD [0001] The present invention relates to a wastewater treatment method,

The present invention relates to a wastewater treatment method and a wastewater treatment apparatus. More particularly, the present invention relates to a wastewater treatment method and a wastewater treatment apparatus that treat nitrogenous wastewater containing ammonia nitrogen by anaerobic ammonia oxidation reaction.

Wastewater from ordinary households or workplaces contains inorganic nitrogen such as ammonia, ammonium compounds, nitrite compounds, and nitric acid compounds, and organic nitrogen such as amino acids and proteins. Nitrogen wastewater containing such a nitrogen component causes eutrophication of the water environment and deterioration of dissolved oxygen, leading to deterioration of water quality pollution. Therefore, emissions to public water bodies are regulated based on drainage standards. Therefore, wastewater treatment for Nitrogen wastewater is being conducted mainly at large-scale business sites and wastewater treatment facilities.

In general, chemical treatment such as a method of removing nitrate nitrogen using ion exchange or a method of oxidizing and decomposing using an oxidizing agent such as ozone is often used as the treatment of nitrogen wastewater of low concentration. On the other hand, biological treatment using microorganisms is performed for the treatment of nitrogenous waste water at a high concentration.

In the biological treatment of the nitrogen-containing wastewater which is conventionally carried out, the treatment of the combination of the nitrification process and the denitration process becomes mainstream since most of the nitrogen component in the wastewater exists as ammonia. As the nitrification process, ammonia nitrogen is oxidized to nitrate nitrogen through nitrite nitrogen and ammonia nitrogen under aerobic conditions by using the oxidizing action of digestive bacteria such as bacteria of the genus Nitrosomonas and bacteria of the genus Nitrobacter And the subsequent denitrification process is a process for converting nitrate nitrogen into harmless nitrogen gas under anaerobic conditions using the reducing action of denitrifying bacteria such as Pseudomonas bacteria ought.

Recently, as a substitute for the treatment combining the nitrification process and the denitrification process, anaerobic ammonia oxidation (ANNAMOX; Anaerobic A mmonium Oxidation] is under way.

Anaerobic ammonia oxidation is a method of converting nitrite nitrogen into ammonia gas by reducing ammonia nitrogen with anaerobic conditions under the action of specific microorganisms. The reaction formula of this conversion is expressed by the following formula 1.

…(식 1)

... (Equation 1)

In the treatment by anaerobic ammonia oxidation, as shown in Equation 1, nitrite nitrogen is required as a substrate. Therefore, a nitrite type oxidation process for converting a part of ammonia nitrogen in the wastewater into nitrite nitrogen is converted into a combination of the former stage.

Conventionally, a combination of a nitriding process and a denitration process, which are generally performed, is difficult to improve the nitrogen treating rate, and a large-capacity treating tank is required for treatment of nitrogen nitrate waste water at a high concentration. In addition, since the denitrifying bacteria used in the denitrification process are generally dependent on nutrition, it is necessary to supply a carbon source, and in the nitrification process, oxygen aeration is required, which is a relatively high treatment cost .

On the other hand, the treatment using anaerobic ammonia oxidation is a promising wastewater treatment method capable of reducing the generation amount of sludge by supplying a carbon source and oxygen aeration, and capable of treating wastewater with high load Attention is being paid.

However, the anaerobic ammonia-oxidizing bacteria that perform the anaerobic ammonia oxidation reaction (ANAMMOX reaction) shown in Equation (1) have a characteristic that when the nitrite nitrogen serving as the substrate becomes high, the activity decreases, and the concentration of the nitrogen component, , Temperature, and C / N ratio, and it is not easy to start (start) the wastewater treatment steadily.

Therefore, as in Patent Document 1, it is possible to improve the operation stability over the long term in the anaerobic ammonia oxidizing apparatus, and it is possible to perform stable operation for a short period of time at the time of starting the operation, A method for operating an anaerobic ammonia oxidation apparatus capable of performing an anaerobic ammonia oxidation treatment, comprising the steps of: circulating the treated water treated in the anaerobic ammonia oxidation tank to the inlet of the anaerobic ammonia oxidation tank and / A technique for adjusting the raw water quantity of the raw water and performing the operation has been proposed.

Japanese Patent Laid-Open No. 2006-110511

The anaerobic ammonia oxidizing bacteria used in the wastewater treatment using anaerobic ammonia oxidation are classified into nitrite nitrogen produced by the nitrite type oxidation reaction combined with the pretreatment by the anaerobic ammonium oxidizing bacteria, ammonia nitrogen contained in the wastewater, By the effect, the activity is inhibited, and stable wastewater treatment can not be maintained. Particularly, when the wastewater treatment apparatus is influenced at the start-up operation, there is a problem that the period required for start-up is prolonged.

Accordingly, an object of the present invention is to provide a means for stably maintaining the treatment by the anaerobic ammonia oxidation carried out in the treatment of nitrogen wastewater with rapid operation.

The present invention, which solves the above problems,

A wastewater treatment method for treating nitrogen oxide wastewater by an anaerobic ammonia oxidation reaction,

A nitrite type oxidation process in which a part of ammonia nitrogen contained in wastewater is oxidized into nitrite nitrogen in the presence of aerobic ammonia oxidizing bacteria,

A diluting water supplying step of supplying diluted water for lowering nitrite nitrogen concentration or ammonia nitrogen concentration or dissolved oxygen concentration in the wastewater to the oxidized wastewater;

And a denitrification process for converting ammonia nitrogen and nitrite nitrogen contained in the oxidized wastewater into nitrogen gas in the presence of anaerobic ammonium oxidizing bacteria.

Further, as a wastewater treatment apparatus for treating nitrogen dioxide wastewater by an anaerobic ammonia oxidation reaction,

A nitrification tank for oxidizing a part of the ammonia nitrogen contained in the wastewater into nitrite nitrogen in the presence of aerobic ammonia oxidizing bacteria,

A diluting water supplying means for supplying a diluting water for lowering nitrite nitrogen concentration or ammonia nitrogen concentration or dissolved oxygen concentration in wastewater to the wastewater discharged from the nitrification tank;

And a denitrification tank for converting ammonia nitrogen and nitrite nitrogen contained in wastewater discharged from the nitrification tank into nitrogen gas in the presence of anaerobic ammonium oxidizing bacteria.

According to the present invention, the treatment by the anaerobic ammonia oxidation performed in the treatment of the nitrogen wastewater can be started quickly and stably.

For example, even if nitrite nitrogen at high concentration, ammonia nitrogen at high concentration, or dissolved oxygen at high concentration exist in the wastewater subjected to anaerobic ammonia oxidation treatment, the influence thereof on anaerobic ammonium oxidizing bacteria can be reduced, It is possible to shorten the time required for starting the operation of the processing apparatus and to continue the stable wastewater treatment in the normal operation after starting.

1 is a configuration diagram of a wastewater treatment apparatus according to an embodiment.
2 is a configuration diagram of a first modification of the wastewater treatment apparatus according to the embodiment.
3 is a configuration diagram of a second modification of the wastewater treatment apparatus according to the embodiment.

A wastewater treatment method, which is an embodiment of the present invention,

A wastewater treatment method for treating nitrogen oxide wastewater by an anaerobic ammonia oxidation reaction,

A nitrite type oxidation process in which a part of ammonia nitrogen contained in wastewater is oxidized to nitrite nitrogen in the presence of aerobic ammonium bacteria,

Supplying diluted water to the oxidized wastewater to reduce nitrite nitrogen concentration or ammonia nitrogen concentration or dissolved oxygen concentration in the wastewater; and supplying ammonia nitrogen and nitrite nitrogen contained in the oxidized wastewater to anaerobic In the presence of ammonia oxidizing bacteria, into a nitrogen gas.

This embodiment is applied to nitrogen-containing wastewater containing ammonia nitrogen as a nitrogen component, and the nitrogen component in the wastewater is converted into nitrogen gas harmless to the environment by the anaerobic ammonia oxidation reaction and treated.

In this embodiment, the treatment is applied to wastewater coming from a household or wastewater coming out of a business place. Specific examples of wastewater to be treated include drainage from a semiconductor factory such as an aqueous phase in which digested sludge is separated from a solid solution in drainage treatment, drainage from a scrubber for ammonia treatment, RCA cleaning wastewater, etc. , Drainage in a metal refinery, waste leachate, and the like.

Therefore, this embodiment is also applied to any of a wastewater treatment apparatus provided individually downstream of a specific drain line of various business sites, or a wastewater treatment apparatus provided in a large-scale wastewater treatment facility such as a sewage treatment plant.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a wastewater treatment method according to an embodiment of the present invention will be described in more detail with reference to the drawings, together with a wastewater treatment device used for carrying out the method.

Fig. 1 is a configuration diagram of a wastewater treatment apparatus 1 that performs a wastewater treatment method according to the embodiment. 1, the wastewater treatment apparatus 1 is a wastewater treatment apparatus composed of a nitrification tank 10 and an denitrification tank 20.

The wastewater containing ammonia nitrogen is first introduced into the nitrification tank 10 as shown by an arrow in Fig. 1, and is subjected to biological treatment under aerobic conditions for a predetermined time in the nitrification zone. Next, it flows out from the nitrification tank 10, flows into the denitrification tank 20 in the direction indicated by the arrow in Fig. 1, stays in the denitrification tank 20 for a predetermined time, and is further subjected to anaerobic ammonia oxidation under anaerobic conditions And the nitrogen component is treated. Thereafter, the wastewater is discharged from the denitrification tank 20 and drained to the outside of the wastewater treatment apparatus 1 as treated water.

A pipe line sucked from a supply source of waste water (not shown) is connected to the upstream end (left end in the figure) of the first treatment joining nitrification tank 10, and wastewater to be treated, And introduced into the wastewater treatment apparatus 1.

On this channel, a water feed pump and a wastewater flow meter (not shown) are provided. Waste water introduced into the wastewater treatment device 1 from the supply source is controlled by the driving force of the water feed pump under the monitoring of the wastewater flow meter. Alternatively, when the wastewater sent from the supply source is pressurized, the flow rate may be controlled by the opening of a water gate, a valve, or the like.

Examples of the source of the wastewater include a storage tank in which treated wastewater is stored and a treatment tank in which pretreatment is performed such as a first sedimentation tank.

The wastewater to be introduced into the wastewater treatment apparatus 1 is preferably subjected to treatment such as filtration, sedimentation and flocculation to remove the main suspended matter and solids, and sulfides and the like which may hinder the treatment It is preferable that it is removed.

Such wastewater may contain environmental factors that are not suitable for the microorganisms used in wastewater treatment, such as excessive concentrations of ammonia nitrogen, other organic components, inorganic components, and the like.

Therefore, when the operation of the wastewater treatment device is started, the start-up operation is usually performed for a predetermined period. It is possible to obtain better nitrogen component processing ability by performing microbial adaptation in starting operation and proliferating until sufficient microbial water is obtained. In the subsequent normal operation, the composition of the wastewater to be treated, temperature, pH conditions, etc. The stable processing can be continued.

The concentration of the ammonia nitrogen of the wastewater to be introduced into the wastewater treatment apparatus 1 is preferably 10 to 2000 mg-N / L, more preferably 40 to 1000 mg-N / L, More preferable.

On the other hand, when the concentration of ammonia nitrogen is excessively high during the start-up operation in which the microorganisms are not subjected to the justification, there is a possibility that the growth and treatment activity of the microorganisms used for wastewater treatment may be inhibited. May be introduced into the wastewater treatment apparatus 1. In this case, In this case, for example, the concentration of ammonia nitrogen is reduced by mixing tap water or the like into the wastewater before it is introduced into the wastewater treatment apparatus 1. With the progress of the microorganisms, the concentration of ammonia nitrogen in the wastewater to be introduced is gradually adjusted to a high concentration and becomes a concentration at the time of normal operation.

The concentration of ammonia nitrogen in the wastewater to be introduced into the wastewater treatment apparatus 1 and the concentration of other nitrogen components can be monitored by providing ammonia-nitrogen measuring means or total nitrogen measuring means on a pipe drawn from the supply source.

In this wastewater treatment device 1, the same microorganisms injected into the biological treatment tank are acclimatized while the same wastewater as the wastewater to be treated at the time of normal operation is introduced. Therefore, the construction of the wastewater treatment device 1 and the subsequent operation at the start of the start-up operation will be described below.

In the start-up operation of the wastewater treatment apparatus 1, the wastewater introduced into the wastewater treatment apparatus 1 first flows into the nitrification tank 10.

The nitrification tank 10 is a treatment tank in which a nitrite type oxidation process is performed in which a part of ammonia nitrogen contained in wastewater is oxidized to nitrite nitrogen in the presence of aerobic ammonia oxidizing bacteria.

Normally, since most of the nitrogen component contained in the wastewater is ammonia nitrogen, part of the ammonia nitrogen is oxidized to nitrite nitrogen, so that the ratio of the substrate in the anaerobic ammonia oxidation reaction shown in Formula 1 is realized . Therefore, in this step, at least a part of the ammonia nitrogen is oxidized to nitrite nitrogen, and a nitrite type oxidation reaction is performed in which nitrite nitrogen is not oxidized from nitrite nitrogen. This nitrite type oxidation reaction is represented by the following formula (2).

…(식 2)

... (Equation 2)

As shown in Formula 2, the nitrite type oxidation process is performed under aerobic conditions.

The nitrification tank 10 mainly includes an aeration means, a dissolved oxygen measurement means 81, a nitrogen component measurement means 91 and an aeration control unit 70.

Other measuring means such as a water temperature measuring means and a pH measuring means may be provided.

The aeration means is means for generating oxygen gas to the wastewater in the nitrification tank 10 so that the biological treatment in the nitrification tank 10 is performed under aerobic conditions.

As the aeration means, any one of a blowing device for performing acid rain in water and an apparatus for mixing air by mechanically stirring the water surface may be used. In this embodiment, as shown in Fig. 1, the blower 60 And is composed of a diffuser 61 and a conveying engine 62.

The blower 60 blows oxygen-containing gas supplied from an oxygen source (not shown) to the diffuser 61 through the air supply pipe 62. The oxygen source is not particularly limited as long as it is a gas containing oxygen gas at a certain concentration, such as air or oxygen enclosed in a tank or the like.

The diffuser 61 increases the dissolved oxygen concentration in the wastewater by oxidizing the blown oxygen gas in the nitrification tank 10 and sets the nitrification tank 10 as an aerobic condition.

1, the diffuser 61 may have any shape such as an air diffuser, an acid substrate, or the like, and the diffuser 61 may be either a film type or a hollow type. It is preferable that the acid mechanism of the diffuser 61 is arranged at a high density and dispersedly disposed in the bottom portion of the nitrification tank 10 so that the steam is stirred by the acid gas to maintain a uniform dissolved oxygen concentration.

The dissolved oxygen measuring means 81 measures the concentration of dissolved oxygen contained in the wastewater.

The dissolved oxygen measuring means 81 is provided in the vicinity of the outlet of the downstream end of the nitrification tank 10 so that dissolved oxygen generated in the treatment in the nitrification tank 10 can be measured And is connected to the aeration control unit 70 through a signal line as indicated by the broken line in Fig.

The dissolved oxygen measuring means 81 may be any of a diaphragm electrode type such as a galvanic type or a polarographic type, a fluorescent type, and the like.

The aeration control section 70 is a control device for controlling the amount of aeration in the nitrification tank 10.

The aeration control unit 70 is connected to the dissolved oxygen measurement unit 81, the nitrogen component measurement unit 91 and the blower 60 via a signal line as indicated by the broken line in Fig.

The aeration control unit 70 is configured to include an operation unit, a signal input / output unit, an A / D and D / A conversion unit, and an operation unit.

The arithmetic unit has arithmetic circuits for calculating proportional control, integral control, and differential control for performing PI control or PID control. Here, the concentration of dissolved oxygen and the conversion of the blower output are performed here.

The signal input / output section has signal input means for receiving the output signal of the measurement means and signal output means for outputting the control signal of the blower.

The A / D and D / A conversion section has a conversion circuit for performing digital conversion and analog conversion of input and output signals.

The operation unit has an input device for inputting a target value of the dissolved oxygen concentration.

The aeration control unit 70 performs feedback control of the dissolved oxygen concentration of the nitrification tank 10 measured by the dissolved oxygen measurement means 81 to the target value of the dissolved oxygen concentration in the aerobic condition of the nitrification tank 10 The control amount of the control is calculated, and the output control of the blower 60 is performed. When the blower 60 is subjected to output control, the amount of oxygen gas to be added to the nitrification tank 10 is increased or decreased, and the dissolved oxygen concentration in the nitrification tank 10 is maintained within the target value range.

In addition, for example, dissolved oxygen measurement means may be provided on a pipeline sucked from the supply source to the wastewater treatment apparatus 1, and the dissolved oxygen measurement means may be connected to the aeration control unit 70, It is possible to perform feedforward control or feedback control according to the dissolved oxygen concentration of the introduced wastewater.

The nitrogen component measuring means 91 measures the concentration of the nitrogen component contained in the wastewater.

The nitrogen component measuring means 91 has at least one of an electrolytic nitrogen system, ammonia nitrogen system and nitrite nitrogen system.

The nitrogen component measuring means 91 is provided near the outlet of the downstream end of the nitrification tank 10 so that the concentration of the total nitrogen component present in the nitrification tank 10 and the concentration of ammonia nitrogen Concentration, or the concentration of nitrite nitrogen produced by the nitrite type oxidation reaction.

Examples of the electrolytic electrolytes include electrolytic electrolyzers based on potassium peroxodisulfate decomposition and catalytic pyrolysis. Examples of the ammonia-nitrogen-based and nitrite-nitrogen-based electrolytes include ion-electrode-type and absorptiometric- .

Is calculated from the total nitrogen component concentration (C ₀ ) in the wastewater and the ammonia nitrogen concentration (C ₁ ) or the nitrite nitrogen concentration (C ₂ ) measured by the nitrogen component measuring means (91) , The nitrification rate R _N in the nitrification tank 10 is calculated.

…(식 3)

... (Equation 3)

As shown in Equation 1, in the anaerobic ammonia oxidation reaction, the ratio of ammonia nitrogen to nitrite nitrogen reacts at 1: 1.32, so that the nitrification rate R _N is about 56 to 57% The nitrite type oxidation reaction needs to be controlled.

As a method of controlling the nitrite type oxidation reaction, the wastewater flowing into the nitrification tank 10 and the wastewater for bypassing the nitrification tank 10 are distributed at a predetermined ratio upstream of the nitrification tank 10, ), There is a method in which the nitrite type oxidation reaction is completely advanced and the bypassed wastewater is remixed so as to achieve a ratio downstream of the nitrification tank 10.

There is also a method of controlling the progress of the nitrite type oxidation reaction so that the nitrification rate is achieved based on the measured values of the ammonia nitrogen and nitrite nitrogen concentrations in the nitrite type oxidation reaction.

Control of the progress of the nitrite type oxidation reaction can be performed by controlling the amount of bubbling, the supply of carbon source, the concentration of ammonia nitrogen, the amount of carrier, the pH, the water temperature and the like.

For example, since alkalinity is consumed by nitriding, an alkaline carbon source such as sodium carbonate or sodium hydrogencarbonate is supplied if necessary, but it can be controlled by the amount thereof.

In the present embodiment, a method of controlling the progress of the nitrite type oxidation reaction is employed in the nitrification tank 10, and the nitrification rate is controlled mainly by adjusting the amount of aeration by the aeration means.

The aeration control unit 70 can operate by inputting the target value of the dissolved oxygen concentration determined from the nitrogen component concentration measured by the nitrogen component measurement unit 91 or the dissolved oxygen concentration measured by the dissolved oxygen measurement unit 81, It is possible to perform control based on the nitrogen component concentration by being connected to the nitrogen component measuring means 91 via a signal line.

For example, by providing the aeration control unit 70 with a calculation unit that calculates the nitrification rate from the total nitrogen component concentration, the ammonia nitrogen concentration, or the nitrite nitrogen concentration measured by the nitrogen component measurement unit 91 according to the equation (3) The output of the blower can be controlled so that the nitrification rate in the nitrification tank 10 achieves the target value.

The operation in the nitrification tank 10 is performed as follows.

In the start-up operation of the wastewater treatment device 1, when the wastewater flows into the nitrification tank 10, the aeration means is driven first.

When the operation of the blower 60 constituting the aeration means is started, an oxygen-containing gas supplied from an oxygen source (not shown), for example, air is blown to the diffuser 61 through the air supply pipe 62, 61 in the nitrification tank 10 from wastewater stored in the nitrification tank 10.

At this time, the dissolved oxygen concentration of the wastewater in the nitrification tank 10 is monitored by the dissolved oxygen measuring means 81.

The measurement signal output from the dissolved oxygen measurement means 81 is input to the aeration control unit 70 and the aeration control unit 70 samples the input measurement signal at a predetermined sampling period.

As aerobic conditions in the nitrite type oxidation reaction performed in the nitrification tank 10, a dissolved oxygen concentration of about 1 to 5 mg / L is required.

Thus, the aeration control section performs feedback control calculation based on the dissolved oxygen concentration to be sampled. As the target value at this time, a predetermined concentration within a range of about 1 to 4 mg / L is set through the operation unit or through the calculation unit of the nitrification rate.

The control amount calculated by the dissolved oxygen concentration control unit is output as a control signal to the blower 60. When the blower 60 receives the control signal, the blowing output is increased or decreased to adjust the dissolved oxygen concentration of the wastewater in the nitrification tank 10 to An oxygen gas of a positive amount which is maintained at a predetermined value is diffused.

When the aeration of the wastewater by the acid of the oxygen gas is performed until the dissolved oxygen concentration of the wastewater is stabilized to a predetermined concentration within a range of about 1 to 5 mg / L, the nitrification tank 10 is continuously supplied with aerobic ammonia Oxidizing bacteria are added.

Aerobic ammonia bacteria are bacteria that convert nitrite nitrogen into nitrite nitrogen by carrying out a nitrite type oxidation reaction using ammonia nitrogen in wastewater as a substrate.

The aerobic ammonia bacteria are preferably immobilized so as not to flow out from the tank. As a method of immobilizing the aerobic ammonia-oxidizing bacteria in the nitrification tank 10, a method of immobilizing the aerobic ammonia bacteria on a carrier or a method of immobilizing the bacteria on a fixed bed Is used.

Examples of the carrier include, but are not limited to, gels such as polyvinyl alcohol, alginic acid, polyethylene glycol, agarose and acrylamide, and plastics such as cellulose, polyester, polypropylene, vinyl chloride and polyurethane.

As a method of immobilizing the support on a carrier, any method may be used, including a method of collectively immobilizing the cells in the carrier, and a method of immobilizing the carrier on the carrier surface.

The shape of the carrier is not particularly limited, but a porous or sponge-like shape molded into a spherical shape, a cylindrical shape, a cubic shape, or a rectangular parallelepiped shape is preferable.

The size of the carrier is preferably 1 to 10 mm, and the filling rate of the carrier is preferably 5 to 50% by volume with respect to the volume of the wastewater.

Examples of the stationary phase include, but are not limited to, plastics such as polyethylene, polyester, polypropylene, and vinyl chloride, activated carbon fibers, and the like.

The shape of the stationary phase is not particularly limited, but a flat plate, a corrugated plate, a fiber form, a chrysanthemum form, a honeycomb form, a stone form, or the like is used.

The porosity of the stationary phase is preferably 80% or more, and the filling rate of the stationary phase is preferably 30 to 80%, more preferably 40 to 80%, of the outer volume of the stationary phase to be charged in the tank.

As aerobic ammo acid bacteria, bacteria that perform a nitrite type nitrification reaction using ammonia as a substrate under aerobic conditions are used.

Examples of such bacteria include bacteria belonging to the genus Nitrosomonas, bacteria belonging to the genus Nitrosococcus, bacteria belonging to the genus Nitrosospira, bacteria belonging to the genus Nitrosovibrio, bacteria belonging to the genus Nitrosolobus, .

Aerobic ammonia-oxidizing bacteria can be isolated from a soil, a river, a lake, a marine environment, an underground water, sludge in drainage, or the like as a single bacterial flora.

In the case where a group of digestive bacteria conventionally used is used as the aerobic ammonia oxidizing bacteria and nitric oxide oxidizing bacteria for oxidizing nitrite are contained in the flour stock, nitric oxide oxidizing bacteria are selectively It is used after elimination processing is performed.

As a method for eliminating nitrite oxidizing bacteria, for example, there is a method using the difference in the behavior due to the presence of ammonia nitrogen between the aerobic ammonia oxidizing bacteria and the nitrite oxidizing bacteria and the difference in growth temperature range.

Concretely, the complex microbial sludge containing aerobic ammonium bacteria and nitrite oxidizing bacteria is subjected to a comprehensive immobilization and then heat-treated at 50 to 90 캜, preferably 60 to 80 캜 for about 2 hours to selectively kill the nitrite- , Or a treatment for selectively killing nitric oxide bacteria by immersing the bacterial flask in acid or alkali can be used. The acid treatment includes, for example, a treatment of immersing in an acid having a pH of 6 or less for 15 minutes or longer, and the alkali treatment is, for example, a treatment of immersing in an alkali of pH 9 or more for 20 minutes or longer.

As shown in Fig. 1, in the present embodiment, such aerobic ammonia-oxidizing bacteria are immobilized in a cuvette-type inclusion immobilization pellet 110 in the nitrification tank 10 and put in the vat 10.

When the aerobic ammonia-oxidizing bacteria are put into the nitrification tank 10 during the start-up operation of the wastewater treatment apparatus 1, the aerobic ammonia-oxidizing bacteria are carried out in the presence of ammonia nitrogen.

The pH of the wastewater in the nitrification tank 10 at this time is adjusted to about pH 6.0 to 8.5, and the water temperature of the wastewater is set to about 10 to 35 占 폚. Further, if necessary, an alkali or a carbon source is supplied.

The nitrogen component measuring means 91 measures the total nitrogen component concentration (C ₀ ), the ammonia nitrogen concentration (C ₁ ) or the nitrite nitrogen concentration (C ₂ ) in the wastewater, The starting operation is performed until the nitrification rate R _N calculated is stabilized at 56 to 57%.

Specifically, the nitrification rate is controlled by setting the target value of the nitrification rate within the range of 56 to 57%. When the nitrification rate is not more than the set range, the dissolved oxygen concentration is set to 5 mg / L, When the concentration is 2 mg / L or more, the dissolved oxygen concentration is set to 1 mg / L and the aeration amount is adjusted.

After the nitriding ratio R _N is stabilized at 56 to 57%, the operation is continued under the same conditions as the normal operation.

The wastewater flowing into the nitrification tank 10 from the starting operation start to the normal operation and staying in the nitrification tank 10 for a predetermined time is supplied to the screen 64 provided at the downstream end of the nitrification tank 10 And the solids are separated and removed by the passage, and are then discharged from the nitrification tank 10.

The wastewater discharged from the nitrification tank 10 then flows into the denitrification tank 20.

The denitrification tank 20 converts ammonia nitrogen contained in wastewater and nitrite nitrogen produced by oxidizing part of the ammonia nitrogen in the nitrification tank 10 into nitrogen gas in the presence of anaerobic ammonium oxidizing bacteria The denitrification process is performed.

In this step, the anaerobic ammonia oxidation reaction represented by the formula (1) is carried out under anaerobic conditions.

The denitrification tank 20 mainly comprises dilution water supply means 40 and 50, stirring means 65, dissolved oxygen measurement means 82 and nitrogen component measurement means 92.

Other measuring means such as a water temperature measuring means and a pH measuring means may be provided.

The diluting water supplying means supplies diluted water to the wastewater that lowers the nitrite nitrogen concentration or the ammonia nitrogen concentration or the dissolved oxygen concentration in the wastewater.

In the present embodiment, as shown in Fig. 1, the diluting water adjusting tank 40 and the diluting water supplying pump 50 are constituted by the diluting water adjusting tank 40 and the diluting water supplying pump 50. However, And a diluting water can be supplied to the wastewater.

The dilution water is supplied to the wastewater in order to alleviate the inhibition of the activity of the bacteria which are subjected to the wastewater treatment by the nitrogen component or the dissolved oxygen at a high concentration which may be contained in the wastewater to be treated. For example, in the anaerobic ammonia-oxidizing bacteria used in the denitrification tank 20, high concentrations of nitrite, ammonia, and dissolved oxygen introduced from the nitrification tank 10 are harmful, thereby obstructing the growth of bacterial water and stable wastewater treatment . By supplying the diluting water for lowering the concentration of these substances in the wastewater, the anaerobic ammonia bacteria injected into the denitrification tank 20 can be appropriately proliferated during start-up of the wastewater treatment apparatus, Waste water treatment can be continued.

The dilution water is not particularly limited as long as it is a liquid having a composition such as tap water, industrial water, industrial wastewater or the like that lowers nitrite nitrogen concentration, ammonia nitrogen concentration or dissolved oxygen concentration in wastewater. However, nitrite nitrogen and ammonia nitrogen Or a liquid in which dissolved oxygen gas is deaerated is preferable.

As such a diluted water, it is preferable to use tap water or industrial water which can be easily obtained because the effect on the wastewater treatment tank is small.

The dilution water adjusting tank 40 is a vessel or vessel for storing dilution water supplied from a dilution water supply source (not shown), and adjusting components, water temperature, pH and the like as necessary.

As the diluted water supply source, for example, water or industrial water may be mentioned.

As for the adjustment of the components, removal of harmful substances such as removal of nitrogen components, removal of dissolved oxygen, hydrogen donors such as methanol, organic nutrients, and useful substances such as inorganic nutrients may be added. In order to remove the nitrogen component or remove dissolved oxygen, an ion exchange membrane, a degassing means, or the like is used. In addition, by providing a degassing means that is later than the dilution water adjusting tank 40, the dissolved oxygen can be removed before mixing the diluted water into the wastewater.

The diluting water supply pump 50 is a pump for sending diluted water and is provided on a pipeline connecting the treating tank and the diluting water adjusting tank 40 or on a pipeline for directly connecting the treating tank and the diluting water supplying source.

As the diluting water supply pump 50, it is preferable to use a metering pump whose discharge amount is controlled.

When this dilution water supply pump 50 is driven, dilution water stored in the adjustment tank 40 is supplied into the treatment tank, and the wastewater in the treatment tank is mixed with dilution water and diluted.

The stirring means 65 stirs the wastewater in the denitrification tank 20 to homogenize the components, water temperature, pH, and the like.

The stirring means 65 shown in Fig. 1 is of the water-intake type, but may be provided on the bottom of the bath or on the bath wall.

If the wastewater locally stays in the tank, the treatment efficiency may be lowered due to inhibition by the nitrite, etc., and the anaerobic ammonium oxidizing bacteria may be reduced. Therefore, it is preferable that the wastewater is always operated during the denitrification process.

The dissolved oxygen measuring means 82 measures the concentration of dissolved oxygen contained in the wastewater and is the same as that provided in the nitrification tank 10.

The denitrification process performed in the denitrification tank 20 is performed under anaerobic conditions. Therefore, the dissolved oxygen measurement means 82 monitors the dissolved oxygen concentration in the denitrification tank 20.

The nitrogen component measuring means 92 measures the concentration of the nitrogen component contained in the wastewater and is the same as that provided in the nitrification tank 10.

The nitrogen component measuring means 92 is installed in the vicinity of the outlet of the downstream end of the denitrification tank 20 so that the concentration of the total nitrogen component present in the denitrification tank 20 and the concentration of ammonia nitrogen Concentration, or the concentration of nitrite nitrogen produced by the nitrite type oxidation reaction. The nitrogen component measuring means 92 measures the nitrogen removal rate which is the ratio of the nitrogen component converted into the nitrogen gas in the denitrification tank 20 and the ammonia nitrogen which can remain as untreated wastewater and can flow out as treated water, The concentration of nitrite nitrogen is monitored.

The operation of the denitrification tank 20 is performed as follows.

When wastewater flows into the denitrification tank 20 as a start-up operation of the wastewater treatment apparatus 1, firstly the agitating means 65 is driven, and the wastewater in the denitrification tank 20 starts convection in the tank.

In the diluting water adjusting tank 40 constituting the diluting water supplying means, diluted water is stored in advance.

Next, the diluting water supply pump 50 is driven, and the supply of the diluting water to the wastewater in the denitration tank 20 is started.

When the dilution water pressurized by the dilution water supply pump 50 is sent to the denitration tank 20, the wastewater and the dilution water are stirred in the denitration tank 20 by the operation of the agitation means 65, do.

The concentration of nitrite nitrogen in the wastewater to be treated at the time of normal operation in the wastewater treatment apparatus 1 of the present embodiment is expected to be relatively high at which the volume load is 0.1 to 5.0 kg-N / m3 / day . Therefore, the concentration of ammonia nitrogen to be introduced into the nitrification tank 10 is relatively high, and thereafter the nitrite nitrogen is oxidized into nitrite nitrogen from the nitrification tank 10 into the denitrification tank 20 The concentration is not suitable for the anaerobic ammonium oxidizing bacterium of the untreated. Therefore, at the time of starting the denitrification tank 20, the concentration of nitrite nitrogen in the wastewater in the denitrification tank 20 is reduced to a low concentration until the completion of the determination of the anaerobic ammonium oxidizing bacteria used in the denitrification tank 20 A positive dilution water is supplied. For example, after the diluted water supply pump 50 is operated until the measured value of nitrite nitrogen by the nitrogen component measuring means 92 is stabilized to about 70 mg-N / L, the operation is stopped.

The dissolved oxygen concentration and the nitrogen component concentration in the denitrification tank 20 at this time can be adjusted also by the inflow amount from the nitrification tank 10 to the denitrification tank 20 together with the adjustment by the diluting water supply means have.

When the dissolved oxygen concentration of the wastewater in the denitrification tank 20 measured by the dissolved oxygen measurement means 82 and the nitrite nitrogen concentration of the wastewater in the denitrification tank 20 measured by the nitrogen component measurement means 92 are high, The amount of dissolved oxygen and nitrite nitrogen introduced into the denitrification tank 20 can be suppressed to a low concentration and the supply amount of the diluted water can be reduced if necessary.

Anaerobic ammonia-oxidizing bacteria are introduced into the denitrification tank 20 in accordance with the dilution of the wastewater by the diluting water supply means. The introduction of the anaerobic ammonium oxidizing bacteria is not limited to the end of the dilution of the wastewater, but may be the supply of the diluted water before the supply of the diluted water is started.

The anaerobic ammonia bacteria are bacteria that convert anaerobic ammonia oxidation reaction to nitrogen gas using ammonia nitrogen and nitrite nitrogen in the wastewater discharged from the nitrification tank 10 as a substrate. A reaction is mainly performed using ammonia nitrogen remaining in the nitrification tank 10 without being subjected to nitrite-type oxidation and nitrite nitrogen generated by a nitrite type oxidation reaction in the nitrification tank 10 as a substrate.

The method of immobilizing the anaerobic ammonia bacteria in the denitrification tank 20 may be a method of immobilizing the anaerobic ammonia oxidizing bacteria on the carrier or a method of immobilizing the bacteria in a stationary phase, A method using self-assembled granules is used.

Examples of the carrier include, but are not limited to, gels such as polyvinyl alcohol, alginic acid, polyethylene glycol, agarose and acrylamide, and plastics such as cellulose, polyester, polypropylene, vinyl chloride and polyurethane.

As a method of immobilizing the support on a carrier, any method may be used, including a method of collectively immobilizing the cells in the carrier, and a method of immobilizing the carrier on the carrier surface.

The shape of the carrier is not particularly limited, but a porous or sponge-like shape molded in a spherical shape, a cylindrical shape, a cubic shape, or a rectangular parallelepiped shape is preferable.

The size of the carrier is preferably 1 to 10 mm, and the filling rate of the carrier is preferably 5 to 50% by volume with respect to the volume of the wastewater.

Examples of the stationary phase include, but are not limited to, plastics such as polyethylene, polyester, polypropylene, and vinyl chloride, activated carbon fibers, and the like.

The shape of the stationary phase is not particularly limited, but a flat plate, a corrugated plate, a fiber form, a chrysanthemum form, a honeycomb form, a stone form, or the like is used.

The porosity of the stationary phase is preferably 80% or more, and the filling rate of the stationary phase is preferably 30 to 80%, more preferably 40 to 80%, of the outer volume of the stationary phase to be charged in the tank.

In the method using granules, it is preferable to convect the wastewater so as to raise and circulate the settling granules in the tank.

For example, by connecting the flow path of the wastewater flowing into the denitration tank 20 from the nitrification tank 10 to the bottom of the denitrification tank 20, the granules are raised from the bottom of the tank by the wastewater flowing in do.

As the anaerobic ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria (ANAMMOX bacteria), which is an autotrophic anaerobic bacteria that utilize ammonia as a hydrogen donor for denitrification, is used.

Examples of such bacteria include bacteria belonging to the genus Brocadia, genus Scalindua, genus Kuenenia, and bacteria having ladderane lipid on the cell membrane.

The anaerobic ammonia oxidizing bacteria are obtained by performing an integrated culture using ammonium nitrogen and nitrite nitrogen as a substrate under anaerobic conditions at a temperature of about 37 ° C and a pH of about 6.5 to 8.0 using, for example, can do.

As shown in Fig. 1, in the present embodiment, such anaerobic ammonia-oxidizing bacteria are immobilized on the cube-like inclusion immobilization pellets 120 and put in the cuvette.

When the anaerobic ammonia-oxidizing bacteria are put into the denitrification tank 20 in the start-up operation of the wastewater treatment device 1, the anaerobic ammonium-oxidizing bacteria are sieved in the diluted wastewater.

At this time, the pH of the wastewater in the denitrification tank 20 is adjusted to about pH 6.0 to 8.5, and the water temperature of the wastewater in the denitrification tank 20 is about 10 to 35 캜. Further, acidity is consumed by denitrification, so that acid such as hydrochloric acid and sulfuric acid is supplied as needed.

During this time, the nitrogen component measuring means 92 monitors the fluctuation of the concentration of the nitrogen component, and the progress of the anaerobic ammonia oxidation reaction is managed. For example, the nitrite nitrogen concentration (C ₂ ) of the wastewater in the denitrifying tank 20 is measured.

When it is ascertained that the nitrite nitrogen concentration in the denitrification tank 20 shows a predetermined decrease, the nitrite nitrogen concentration in the denitrification tank 20 is increased stepwise to advance the anaerobic ammonia oxidizing bacteria.

For example, if it is confirmed that the nitrite nitrogen concentration in the diluted wastewater at the start of the cultivation is lowered to about 25 to 50%, the nitrite nitrogen concentration in the denitrification tank 20 is adjusted to 100 mg / L to 1000 mg / L , And the transfer of the anaerobic ammonia oxidizing bacteria to a higher concentration level. Thereafter, when it is confirmed that the nitrite nitrogen concentration again rises, the nitrite nitrogen concentration in the denitrification tank 20 is raised again.

Here, the increase of the nitrite nitrogen concentration is mainly performed by controlling the progress of the nitrite type oxidation in the nitrification tank 10 and controlling the supply amount of the diluting water.

By repeating such a process, the anaerobic ammonia-oxidizing bacteria are immediately subjected to the same operation, and the nitrogen removal rate in the denitrification tank 20 is increased to a speed required at the time of normal operation.

Thereafter, in the denitrification tank 20, normal operation continues at a predetermined volume load and a predetermined residence time.

When the nitrite nitrogen concentration or the ammonia nitrogen concentration or the dissolved oxygen concentration fluctuates at a high concentration even in the normal operation, dilute water is supplied to the wastewater so that nitrite nitrogen concentration in the denitrification tank 20 Or ammonia nitrogen concentration or dissolved oxygen concentration can be reduced. For example, the dilution water supply control unit for controlling the amount of diluting water to be supplied is connected to the diluting water supply unit, and the measured value of the nitrogen component measuring unit 92 is inputted to the diluting water supply control unit. In the dilution water supply control section, feedback control of the nitrite nitrogen concentration or ammonia nitrogen concentration in the denitrification tank 20 is performed to calculate the output of the dilution water supply pump 50 provided in the dilution water supply means . The dilution water supply control unit and the dilution water supply unit provided in the denitrification tank 20 are so constructed that the measurement values of the nitrogen component measurement unit 91 provided in the nitrification tank 10 are input to the dilution water supply control unit, The feedforward control based on the fluctuation of the nitrite nitrogen concentration or the ammonia nitrogen concentration in the nitrification tank 10 is performed.

The wastewater that has stayed in the denitrification tank 20 for a predetermined time passes through the screen 64 provided at the downstream end of the denitrification tank 20 to separate and remove solid matter from the denitrification tank 20. At the downstream end (the right end in the figure) of the denitrification tank 20, there is formed a drainage channel connected to the outside of the wastewater treatment device 1, and the wastewater from which the nitrogen component has been removed passes through the drainage treatment device 1 as the treated water.

According to the wastewater treatment apparatus 1 having such a diluted water supply means, the concentration of nitrite nitrogen and ammonia nitrogen in the denitrification tank 20 can be managed, and therefore, the denitration treatment can be stably continued.

Further, since the anaerobic ammonium-oxidizing bacteria are less susceptible to the nitrite nitrogen and ammonia nitrogen in the wastewater, the time required for the anaerobic ammonia-oxidizing bacteria to be homogenized is shortened and the time required for the start-up operation is inhibited can do.

Further, since the concentration of nitrite nitrogen and ammonia nitrogen in the wastewater brought into contact with the anaerobic ammonia-oxidizing bacteria put into the treatment tank can be freely increased or decreased by the operation of the diluting water supplying means, a special operating means or pure wastewater is required It is possible to start the wastewater treatment apparatus by using nitrogen wastewater with the same apparatus configuration as in the normal operation.

[Modified Example 1]

Next, a first modification of the embodiment of the present invention will be described.

2 is a configuration diagram of a first modification of the wastewater treatment apparatus according to the embodiment. 2, the wastewater treatment apparatus 2 is a wastewater treatment apparatus composed of three tanks in which a degassing tank 30 is additionally provided between the nitrification tank 10 and the denitrification tank 20 .

The wastewater containing ammonia nitrogen is first introduced into the nitrification tank 10 as shown by an arrow in Fig. 2, and is retained in the nitrification tank for a predetermined time to undergo biological treatment under aerobic conditions. Next, it flows out from the nitrification tank 10, flows into the degassing vessel 30 in the direction indicated by the arrow in FIG. 2, and stays in the degassing vessel 30 for a predetermined time to degas the dissolved oxygen. Next, the water is introduced into the denitrification tank 20, stays in the denitrification tank 20 for a predetermined time, and subjected to biological treatment by anaerobic ammonia oxidation under anaerobic conditions to treat the nitrogen component. Thereafter, the wastewater is discharged from the denitrification tank 20 and discharged to the outside of the wastewater treatment apparatus 2 as treated water.

This wastewater treatment apparatus 2 includes a nitrification tank 10 and an denitrification tank 20 having the same constitution in the wastewater treatment system 1.

(Not shown) is connected to the upstream end (left end in the figure) of the nitrification tank 10, and at the downstream end (right end in the drawing) of the denitrification tank 20, And a duct for receiving the water to be connected to the outside of the water tank 2 is formed.

The configuration of the wastewater treatment device 2 and the operation at the start of the start operation will be described below.

When the start-up operation of the wastewater treatment device 2 is started, the wastewater containing ammonia nitrogen, which is sent from the supply source, is first introduced into the nitrification tank 10, as in the wastewater treatment device 1.

In the nitrification tank 10, similarly to the wastewater treatment apparatus 1, the nitrite type oxidation process is controlled so that the nitrification rate is 56 to 57%, and the wastewater that has stayed in the nitrification tank 10 for a predetermined time , And flows out from the nitrification tank (10).

Subsequently, in the wastewater treatment apparatus 2, the wastewater flowing out of the nitrification tank 10 flows into the degassing tank 30.

The degassing vessel (30) is a treatment tank in which a degassing process for degassing dissolved oxygen in the wastewater is performed.

The oxygen supplied to the wastewater in the nitrite type nitrification process carried out under aerobic conditions is a factor inhibiting the reaction in the anaerobic ammonia oxidation reaction carried out under anoxic conditions.

Therefore, in this step, dissolved oxygen that has become high in concentration due to aeration in the nitrification tank 10 is deaerated, and the wastewater suited to the anaerobic conditions for performing the anaerobic ammonia oxidation is operated to be introduced into the denitrification tank 20.

The degassing vessel 30 is mainly provided with degassing means and dissolved oxygen measuring means 83.

Other measurement means such as a deaeration control unit (not shown), a nitrogen component measurement unit, a water temperature measurement unit, and a pH measurement unit may be provided.

The degassing means is a means for degassing the oxygen gas dissolved in the wastewater flowing into the degassing vessel (30).

As the degassing means, any of a degreasing type apparatus for providing a gas-permeable membrane at the vapor-liquid interface, a blow-in apparatus for performing oxygen gas oxygenation in water, an apparatus for adsorbing and removing oxygen, and an apparatus for adding an oxygen scavenger , And an apparatus based on an oxygen-free gas is preferred because oxygen in the air is less redissolved.

In the present embodiment, the degassing means is constituted by a blower 63, a diffuser 61, and a delivery pipe 62 as shown in Fig.

The blower 63 blows the oxygen-free gas supplied to the oxygen-free gas source (not shown) to the diffuser 61 through the air line 62. The oxygen-free gas is not particularly limited as long as it is a gas which does not substantially contain oxygen gas such as nitrogen gas, carbon dioxide gas, and rare gas and is a gas having relatively low solubility in wastewater.

The diffuser 61 reduces the solubility of oxygen in the wastewater by oxidizing the blown oxygenated gas into the degassing vessel 30, thereby performing degassing of the oxygen gas.

2, the diffuser 61 may have any shape such as an air diffuser, an acid substrate, or the like, and the diffuser 61 may be either a membrane type or a hollow type. It is preferable that the acid mechanism of the diffuser 61 is disposed at the bottom of the degassing vessel 30 at a high density and dispersedly so as to be uniformly degassed.

The dissolved oxygen measuring means 83 measures the concentration of dissolved oxygen contained in the wastewater and is the same as that provided in the nitrification tank 10.

The dissolved oxygen measuring means 83 is installed in the vicinity of the outlet of the downstream end of the degassing vessel 30 so as to measure the dissolved oxygen that can flow out to the downstream end.

The operation of the degassing vessel 30 is performed as follows.

When the wastewater flows into the degassing vessel 30, an oxygen-free gas, for example, carbon dioxide gas supplied from an oxygen-free gas source (not shown) And diffused into the wastewater stored in the degassing vessel 30 from the acid mechanism of the diffuser 61. [

Normally, the dissolved oxygen concentration in the anaerobic condition of the denitrification tank 20 is controlled to be 0.5 mg / L or less, preferably 0.2 mg / L or less, at 25 to 30 ° C water temperature.

Therefore, under the monitoring of the dissolved oxygen concentration by the dissolved oxygen measuring means 83, oxygen gas is diffused to such an extent that the dissolved oxygen of the wastewater in the degassing vessel 30 is completely removed.

The oxygen-containing gas can be generated at any time, intermittently in accordance with fluctuations in the measured value of the dissolved oxygen concentration in the wastewater, or adjusted by adjusting the amount of acid.

For example, by providing a deaeration control unit (not shown) connected to the blower 63 and the dissolved oxygen measurement unit 83 through a signal line, the amount of acid gas can be controlled based on the measured dissolved oxygen concentration.

The degassing control unit is configured to include an operation unit, a signal input / output unit, an A / D and a D / A conversion unit, and an operation unit. The dissolved oxygen concentration of the degassing vessel 30 measured by the dissolved oxygen measurement unit 83, The control amount of the feedback control to be controlled to the target value of the dissolved oxygen concentration in the anaerobic condition of the denitrification tank 20 is calculated and the output of the blower 63 is controlled. When the blower 63 is subjected to output control, the amount of oxygen gas to be supplied to the denitrification tank 30 is increased or decreased, and the dissolved oxygen concentration in the degassing vessel 30 is maintained within the target value range.

However, at the time of start-up, it is preferable to perform deaeration more than a predetermined amount until the progress of the anaerobic ammonia bacteria proceeds. When the anaerobic ammonia oxidation proceeds in the denitrification process, the concentration of the nitrogen gas increases, and the influence of the dissolved oxygen in the wastewater is alleviated. Therefore, the amount of deaeration may be controlled to a maximum value at the time of starting.

The wastewater which has stayed in the degassing vessel 30 for a predetermined time and the dissolved oxygen has been degassed then flows out from the degassing vessel 30 and flows into the denitration tank 20.

In the denitrification tank 20, the denitrification process by the anaerobic ammonia oxidation is performed in the same manner as in the wastewater treatment device 1.

First, the anaerobic ammonia-oxidizing bacteria are sown under the nitrite nitrogen concentration stepwise adjusted by the operation of the diluting water supply means, and then nitrogen removal is performed as normal operation for the wastewater having the nitrite nitrogen concentration that is pulled up .

The wastewater that has stayed in the denitrification tank 20 for a predetermined time flows out of the denitrification tank 20 and is discharged to the outside of the wastewater treatment device 2 through a drainage pipe connected to the outside of the wastewater treatment device 2 Respectively.

According to the wastewater treatment apparatus 2 having the degassing vessel 30, dissolved oxygen in wastewater having a high concentration in the nitrite type oxidation process can be reliably removed before being supplied to the anaerobic ammonia oxidation reaction, The denitration treatment can be continued.

Further, because the anaerobic ammonium-oxidizing bacteria are less susceptible to the influence of the dissolved oxygen in the wastewater, the time required for the anaerobic ammonium-oxidizing bacteria to be homogenized is shortened, and the prolonged time required for the start-up operation can be suppressed.

In addition, stable denitrification treatment can be continued in the treatment in which the amount of aeration is increased, for example, when treating a nitrogenous waste wastewater of high concentration.

[Modified example 2]

Next, a second modification of the embodiment of the present invention will be described.

3 is a configuration diagram of a second modification of the wastewater treatment apparatus according to the embodiment. 3, the wastewater treatment device 3 is provided between the nitrification tank 10 and the denitrification tank 20 in the same manner as the wastewater treatment device 2, And is a wastewater treatment device composed of a bath.

The wastewater treatment device 3 is different from the wastewater treatment device 2 in that the dilution water supply means is connected to the degassing vessel 30. [

As shown by an arrow in Fig. 3, the wastewater containing ammonia nitrogen is first introduced into the nitrification tank 10, is kept in the nitrification tank for a predetermined time, and is subjected to biological treatment under aerobic conditions. Next, it flows out from the nitrification tank 10, flows into the degassing vessel 30 in the direction indicated by the arrow in Fig. 3, and stays in the degassing vessel 30 for a predetermined time to degas the dissolved oxygen. Next, the water is introduced into the denitrification tank 20, stays in the denitrification tank 20 for a predetermined time, and subjected to biological treatment by anaerobic ammonia oxidation under anaerobic conditions to treat the nitrogen component. Thereafter, the wastewater is discharged from the denitrification tank 20 and discharged to the outside of the wastewater treatment apparatus 2 as treated water.

The wastewater treatment apparatus 3 includes a nitrification tank 10 having the same structure as the wastewater treatment system 2, a denitrification tank 20, and a degassing tank 30.

However, in the wastewater treatment system 2, the dilution water supply means provided in the denitrification tank 20 is provided in the degassing vessel 30 in the wastewater treatment device 3. In the degassing vessel 30, a nitrogen component measuring means 93 is provided.

A conduit to be sucked from a supply source of waste water (not shown) is connected to the upstream end (in the figure) of the nitrification tank 10, and a waste water treatment device 3 is connected to the outside of the main body.

The configuration of the wastewater treatment device 3 and the subsequent operation at the start of the start operation will be described below.

When the start-up operation of the wastewater treatment device 3 is started, the wastewater containing ammonia nitrogen sent from the supply source is first introduced into the nitrification tank 10, as in the wastewater treatment device 2.

In the nitrification tank 10, as in the wastewater treatment apparatus 2, the nitrite type oxidation process is performed so that the nitrification rate is controlled to be 56 to 57%, and the wastewater that has stayed in the nitrification tank 10 for a predetermined time , And flows out from the nitrification tank (10).

Next, the wastewater flowing out of the nitrification tank 10 flows into the degassing vessel 30.

At this time, in the dilution water adjusting tank 40 constituting the diluting water supplying means connected to the degassing tank 30, diluted water is stored in advance.

In the degassing vessel 30, a degassing step for degassing the dissolved oxygen in the wastewater is performed as in the wastewater treatment apparatus 2. In addition, the dilution water supply process is started at about the same time as the degassing of the dissolved oxygen.

The degassing is carried out so that the dissolved oxygen concentration in anaerobic conditions flowing into the denitrification tank 20 is 0.5 mg / L or less, preferably 0.2 mg / L or less, at 25 to 30 ° C water temperature, Degassing is performed under the monitoring of the measuring means 83. [

The diluting water in the degassing tank 30 is supplied in the same manner as in the wastewater treatment apparatus 2. [

The concentration of nitrite nitrogen in the wastewater flowing from the nitrification tank 10 into the denitrification tank 20 at the time of normal operation in the wastewater treatment apparatus 3 is set to a value A relatively high concentration is expected to be 0.1 to 5.0 kg-N / m3 / day. Therefore, the concentration of the ammonia nitrogen introduced into the nitrification tank 10 is relatively high, and thereafter the nitrite type oxidation is carried out from the nitrification tank 10 to the denitrification tank 20 via the degassing tank 30 The concentration of nitrite nitrogen in the effluent is at a concentration that is not suitable for the acute amount of anaerobic ammonia oxidizing bacteria. Therefore, until the anaerobic ammonia-oxidizing bacteria used in the denitrification tank 20 are completely used, a positive dilution water for reducing the nitrite nitrogen concentration in the wastewater flowing into the denitrification tank 20 at a low concentration, 30). For example, after the diluted water supply pump 50 is operated until the measured value of nitrite nitrogen by the nitrogen component measuring means 93 is stabilized to about 70 mg-N / L, the operation is stopped.

When the diluted water pressurized by the dilution water supply pump 50 is sent to the degassing vessel 30, the wastewater and the dilution water are stirred in the degassing vessel 30. Stirring is usually carried out by an acidification by means of a degassing means.

The wastewater which has been retained in the degassing vessel 30 for a predetermined time and diluted and dissolved oxygen is deaerated flows out of the degassing vessel 30 and flows into the denitration tank 20.

In the denitrification tank 20, as in the wastewater treatment apparatus 2, a denitration process by anaerobic ammonia oxidation is performed.

First, the anaerobic ammonia oxidizing bacteria are sieved in diluted wastewater in the degassing tank 30.

When it is ascertained that the nitrite nitrogen concentration in the denitrification tank 20 shows a predetermined decrease, the nitrite nitrogen concentration introduced into the denitrification tank 20 is increased stepwise to advance the anaerobic ammonia oxidizing bacteria.

For example, if it is confirmed that the nitrite nitrogen concentration in the diluted wastewater at the start of the cultivation is lowered to about 25 to 50%, the nitrite nitrogen concentration in the denitrification tank 20 is adjusted to 100 mg / L to 1000 mg / L , And the sludge of the anaerobic ammonium oxidizing bacteria is shifted to a higher concentration stage. Thereafter, when it is confirmed that the nitrite nitrogen concentration again rises, the nitrite nitrogen concentration in the denitrification tank 20 is raised again.

Here, the increase of the nitrite nitrogen concentration is mainly performed by controlling the supply amount of the diluting water in the degassing tank 30 and controlling the progress of the nitrite type oxidation in the nitrification tank 10.

By repeating such a process, the nitrogen removal rate in the denitrification tank 20 is increased to a speed required at the time of normal operation.

Thereafter, in the denitrification tank 20, normal operation continues at a predetermined volume load and a predetermined residence time.

In the case where the nitrite nitrogen concentration or the ammonia nitrogen concentration or the dissolved oxygen concentration fluctuates at a high concentration even in the normal operation, it is preferable that the dilution water is supplied to the wastewater in the degassing tank 30, The nitrite nitrogen concentration or the ammonia nitrogen concentration or the dissolved oxygen concentration in the storage tank 20 can be reduced. For example, in the degassing tank 30, a dilution water supply control unit for controlling the amount of diluting water to be supplied is provided so as to be connected to the dilution water supply unit, and the dilution water supply control unit is provided with the nitrogen component measurement unit 93 Value is input. In the dilution water supply control unit, feedback control of the nitrite nitrogen concentration or the ammonia nitrogen concentration in the degassing tank 30 is performed and the output of the dilution water supply pump 50 provided in the dilution water supply means . The dilution water supply control unit and the dilution water supply unit provided in the degassing tank 30 are so constructed that the measurement values of the nitrogen component measurement unit 91 provided in the nitrification tank 10 are input to the dilution water supply control unit, The feedforward control based on the fluctuation of the nitrite nitrogen concentration or the ammonia nitrogen concentration in the nitrification tank 10 is performed.

The wastewater which has stayed in the denitration tank 20 for a predetermined time is drained from the denitrification tank 20 to the outside of the wastewater treatment device 3 through a drainage channel connected to the outside of the wastewater treatment device 3 .

According to the wastewater treatment apparatus 3 provided with the degassing vessel 30, dissolved oxygen in wastewater having a high concentration by the nitrite type oxidation process can be reliably removed before being supplied to the anaerobic ammonia oxidation reaction, The denitration treatment can be continued.

In addition, since the anaerobic ammonium oxidizing bacteria are less susceptible to the influence of dissolved oxygen in the wastewater, the time required for the anaerobic ammonia oxidizing bacteria to be homogenized is shortened, and the time required for the start-up operation is prevented from being prolonged.

In addition, stable denitrification treatment can be continued in the treatment in which the amount of aeration is increased, for example, when treating a nitrogenous waste wastewater of high concentration.

By connecting the dilution water supply means to the degassing vessel 30, the dilution water can be deaerated in the degassing vessel 30, and the dissolved oxygen of the diluted wastewater flowing into the denitration vessel 20 can be further purified The concentration can be reduced.

{Example}

Next, embodiments of the present invention will be described in detail.

[Example 1]

As the first embodiment, the wastewater treatment apparatus 1 relating to the embodiment was used to conduct the wastewater treatment of the nitrogen-containing wastewater assumed to be in the starting operation.

As the raw water to be treated, synthetic wastewater simulating wastewater containing ammonia nitrogen was used.

The ammonia nitrogen concentration of this synthetic wastewater was increased stepwise from 150 mg-N / L to 1000 mg-N / L.

(Nitrite type oxidation process)

Initially, as a nitrite type oxidation process, approximately half of the ammonia nitrogen in the raw water was oxidized to nitrite nitrogen in the presence of aerobic ammonia oxidizing bacteria.

As the aerobic ammonia-oxidizing bacteria, sludge containing aerobic ammonium-oxidizing bacteria was added to the nitrification tank as a bulk immobilization support in a volume ratio of 20%.

The temperature of the nitrification tank was adjusted to 30 ° C, the pH thereof was adjusted to pH 7.6 using an aqueous solution of sodium hydrogencarbonate, and Mg, K, Na and phosphate were added as inorganic nutrients.

The volume load of the nitrification tank was operated at 1.0 to 3.0 kg-N / m3 / day.

The nitrification rate in the nitrification tank was calculated in accordance with Equation (3) by measuring the total nitrogen (C ₀ ) and the ammonia nitrogen concentration (C ₁ ) by providing the electrolyzer and the ammonium ion electrode.

In this example, the target value of nitrification rate in the nitrite type oxidation process was set to 56 to 57%, and the nitrification rate was controlled by adjusting the amount of dissolved oxygen by controlling the aeration amount. Specifically, when the measured nitrification rate is less than the target value range, the concentration of dissolved oxygen is controlled to be 5 mg / L, and when the nitrification rate is within the target value range, the dissolved oxygen concentration is controlled to be 2 mg / L, In the case of exceeding the value range, the concentration of dissolved oxygen was controlled to be 1 mg / L.

(Denitrification process)

Next, in the denitrification process, ammonia nitrogen and nitrite nitrogen in raw water were converted into nitrogen gas by anaerobic ammonia oxidation in the presence of anaerobic ammonium oxidizing bacteria.

As the anaerobic ammonium oxidizing bacteria, a small amount of sludge containing anaerobic ammonium oxidizing bacteria was used as a collective immobilization support, and the contents were added to the denitrification tank at a volume ratio of 20%.

The temperature of the denitrification tank was adjusted to 30 DEG C and the pH was adjusted to 7.6 using an aqueous solution of sodium hydrogencarbonate.

The volume load of the denitrification tank was operated at 0.1 to 5.0 kg-N / m3 / day.

Diluted water was supplied to the denitrifying raw water to dilute the nitrite nitrogen concentration to about 70 mg-N / L.

As dilution water, industrial wastewater having a dissolved oxygen concentration of about 7 mg / L was used.

When the concentration of nitrite in the denitrification tank is lowered to 20 mg-N / L due to the progress of the anaerobic ammonia oxidation, the nitrite nitrogen concentration after dilution is reduced to 200 mg-N / L such as 200 mg-N / L and 400 mg- , The ammonia nitrogen concentration of the synthetic wastewater was increased.

(result)

As a result, the nitrogen component removal rate after 120 days from the start of the start-up operation was 1.0 kg-N / m3 / day.

[Example 2]

As the second embodiment, the wastewater treatment apparatus 2 relating to the first modification example was used to conduct a wastewater treatment test on nitrogen-containing wastewater assumed to be in a starting operation.

As the raw water to be treated, synthetic wastewater simulating wastewater containing ammonia nitrogen was used.

The ammonia nitrogen concentration of synthetic wastewater was increased stepwise from 150 mg-N / L to 1000 mg-N / L.

(Nitrite type oxidation process)

First, the nitrite type oxidation process was carried out in the same manner as in Example 1.

(Degassing process)

Next, as the degassing step, the oxygen in the raw water that has undergone the nitrite type oxidation process is removed by degassing.

The degassing was carried out by producing carbon dioxide gas in raw water by a membrane diffuser provided at the bottom of the degassing vessel.

The water temperature in the degassing tank was 30 占 폚, the residence time was 30 minutes, and the deaeration was performed so that the dissolved oxygen concentration in the raw water after the degassing process was 0.5 mg / L or less.

(Denitrification process)

Subsequently, the denitration process was carried out in the same manner as in Example 1.

(result)

As a result, it was confirmed that the dissolved oxygen concentration of the raw water flowing into the denitrifying tank was reduced to about 0.5 mg / L by passing the degassing tank.

After 92 days from the start of the starting operation, the nitrogen component removal rate reached 4. O kg-N / m 3 / day, and the diluted water with relatively high dissolved oxygen concentration was supplied without degassing in Example 1 Compared with the results, it was recognized that, in a shorter period of time, high-speed nitrogen removal was achieved. These results indicate that the anaerobic ammonia-oxidizing bacteria are susceptible to the influence of dissolved oxygen at the time of start-up operation, suggesting that the removal of the dissolved oxygen of the raw water flowing into the denitrification tank is effective.

[Referential Example 1]

As a reference example 1, a wastewater treatment test for nitrogen wastewater wastewater assumed to be in a normal operation state was conducted using the wastewater treatment apparatus 1 according to the embodiment without supplying diluted water.

As the raw water to be treated, synthetic wastewater simulating wastewater containing ammonia nitrogen was used.

The ammonia nitrogen concentration of the synthetic wastewater was set to 1000 mg-N / L.

(Nitrite type oxidation process)

First, the nitrite type oxidation process was performed in the same manner as in Example 1. [ However, the comprehensively immobilized carrier containing aerobic ammo acid bacteria was used beforehand in a separate group before the purification.

(Denitrification process)

Next, the denitration process was carried out in the same manner as in Example 1. However, the inclusion immobilization support containing the anaerobic ammonium oxidizing bacteria was used after the pretreatment in the separate group in advance.

(result)

In this test, the nitrification tank and the denitrification tank were charged with a carrier which had been pretreated in a separate tank, so that the activity of the nitrite type oxidation reaction and the anaerobic ammonia oxidation reaction was obtained immediately after each carrier was charged. Therefore, the concentration of dissolved oxygen in the nitrification tank was controlled to be in the range of 2 to 5 mg / L by using the aeration means.

On the other hand, the measured value of the dissolved oxygen concentration in the nitrification tank fluctuates within a range of 1 to 6 mg / L, and the dissolved oxygen concentration in the nitrification tank may show a relatively high value exceeding the control target value .

As a result of the operation under these conditions, the nitrogen removal rate after the denitrification process was 70 to 84%, which was a relatively low value compared with the planned nitrogen removal rate.

This result is thought to be caused by the fact that the dissolved oxygen of the nitrification tank flows into the denitrification tank and the activity of the anaerobic ammonium oxidizing bacteria is locally inhibited by the dissolved oxygen.

[Reference Example 2]

As a reference example 2, the wastewater treatment test of the nitrogen-containing wastewater assumed to be in the normal operation was performed by using the wastewater treatment apparatus 2 according to the first modification, without supplying diluted water.

As the raw water to be treated, synthetic wastewater simulating wastewater containing ammonia nitrogen was used.

The ammonia nitrogen concentration of the synthetic wastewater was set at 1000 mg-N / L.

(Nitrite type oxidation process)

First, the nitrite type oxidation process was performed in the same manner as in Example 1. [ However, the comprehensively immobilized carrier containing aerobic ammo acid bacteria was used beforehand in a separate group before the purification.

(Degassing process)

Next, the degassing process was performed in the same manner as in Example 2. [

(Denitrification process)

Subsequently, the denitration process was carried out in the same manner as in Example 1. However, the inclusion immobilization support containing the anaerobic ammonium oxidizing bacteria was used after the pretreatment in the separate group in advance.

(result)

In this test, as in Reference Example 2, the nitrification tank and the denitrification tank were charged with a carrier in which pretreatment was carried out in a separate tank in advance, so that the concentration of dissolved oxygen in the nitrification tank was maintained at a range of 2-5 mg / And control was carried out using the means.

As a result of the operation under these conditions, the nitrogen removal rate after the denitrification process was stable within the range of 80 to 86% by passing the deaeration tank through.

This result shows that even when the dissolved oxygen concentration in the raw water in the nitrification tank fluctuates to the high concentration side, the dissolved oxygen concentration in the raw water flowing into the denitrifying tank is lowered by the degassing step, and the inhibition of the activity of the anaerobic ammonium oxidizing bacteria Was reduced.

1: Wastewater treatment system 2: Wastewater treatment system
3: wastewater treatment system 10: nitrification tank
20: denitrification tank 30: degassing tank
40: diluting water adjusting tank 50: diluting water supplying pump
60: blower 61: diffuser
62: transmission organ 63: blower
64: Screen 65: Agitating means
70: Aeration control section 81, 82, 83: Dissolved oxygen measurement means
91, 92, 93: Nitrogen component measuring means
110: Aerobic ammo acid bacteria immobilized support
120: Ammonia-oxidizing bacteria immobilized carrier

Claims (8)

A wastewater treatment method for treating nitrogen oxide wastewater by an anaerobic ammonia oxidation reaction,
A nitrite type oxidation process in which a part of ammonia nitrogen contained in wastewater is oxidized to nitrite nitrogen in the presence of aerobic ammonium bacteria,
A diluting water supplying step of supplying diluted water for lowering nitrite nitrogen concentration or ammonia nitrogen concentration or dissolved oxygen concentration in the wastewater to the oxidized wastewater;
And a denitrification process for converting ammonia nitrogen and nitrite nitrogen contained in the oxidized wastewater into nitrogen gas in the presence of anaerobic ammonium oxidizing bacteria. The method according to claim 1,
Further comprising a degassing step of degassing dissolved oxygen in the oxidized wastewater between the nitrite type oxidation step and the denitration step. 3. The method of claim 2,
Wherein the degassing step is performed together with the diluting water supplying step. 4. The method according to any one of claims 1 to 3,
Characterized in that the method is carried out at the start-up operation of a wastewater treatment apparatus for treating nitrogen-containing wastewater by an anaerobic ammonia oxidation reaction. A wastewater treatment apparatus for treating nitrogen oxide wastewater by an anaerobic ammonia oxidation reaction,
A nitrification tank for oxidizing a part of the ammonia nitrogen contained in the wastewater into nitrite nitrogen in the presence of aerobic ammonia oxidizing bacteria,
A diluting water supplying means for supplying a diluting water for lowering nitrite nitrogen concentration or ammonia nitrogen concentration or dissolved oxygen concentration in wastewater to the wastewater discharged from the nitrification tank;
And an denitrification tank for converting ammonia nitrogen and nitrite nitrogen contained in the wastewater discharged from the nitrification tank into nitrogen gas in the presence of anaerobic ammonium oxidizing bacteria. 6. The method of claim 5,
Further comprising a degassing vessel provided between the nitrification tank and the denitrification tank for degassing dissolved oxygen in the wastewater flowing out of the nitrification tank. The method according to claim 6,
Wherein the diluted water supply means is connected to at least one of the deaeration tank and the denitrification tank. 8. The method according to any one of claims 5 to 7,
Wherein the diluted water supply means is activated at the start-up operation of the wastewater treatment device.

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