JPH10165975A - Waste water treatment apparatus with carrier expansion phase - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve water quality of treated water by an apparatus wherein an aeration means for forming an aeration phase on the upper part of a deep tank type bioreactor and a circulation means for forming a static water phase between a carrier expansion phase formed in the lower part of the bioreactor and wherein a carrier carrying microorganism floats up slightly and an aeration phase are installed. SOLUTION: After waste water flowing into a bioreactor 16 is sufficiently aerated in an aeration phase 42 by means of an aeration device 18, it is lowered as a downward stream in a communication pipe 26 and is delivered to the bottom part of the bioreactor 16. The waste water delivered to the bottom part of this bioreactor 16 is elevated as a up-blow in the bioreactor 16 and by keeping linear velocity when it passes through a carrier expansion phase 46 formed on the lower part of the bioreactor 16 at 0.5-7cm/sec, a static water phase 48 with a flow velocity at which the carrier 14 can enough naturally settle is formed in the water region on the top side of the carrier expansion phase 46. In addition, aerobic atmospheres are formed in the upper part and the lower part of the bioreactor 16 and BOD ingredient and ammoniacal nitrogen are mainly nitrification-treated respectively in the aeration phase 42 and the carrier expansion phase 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating a carrier expanded phase wastewater, and more particularly to an apparatus for treating a carrier expanded phase wastewater which reduces BOD components, ammophilic nitrogen and the like contained in sewage and industrial wastewater.

[0002]

2. Description of the Related Art In recent years, as a part of environmental pollution prevention, it is required to improve the quality of treated water discharged from a sewage treatment plant for treating wastewater such as sewage. BO in wastewater
D. As one of the water treatment methods for reducing ammoniacal nitrogen, 6 to 20% by volume of a carrier entrapping and immobilizing microorganisms or a combined carrier is accommodated in a biological reaction tank, and air is blown from the entire bottom surface of the biological reaction tank. In this method, aeration is performed to form an aerobic atmosphere in the biological reaction tank, and the carrier is uniformly floated and flowed by the aerated air. In this method, the BOD component is oxidatively decomposed in an aerobic atmosphere mainly by activated sludge floating in water, and the ammonia nitrogen is sublimated in an aerobic atmosphere by nitrifying bacteria supported on a carrier and nitrifying bacteria in the activated sludge. Designed to be oxidized to nitric acid or nitric acid.

[0003] In urban areas, the site of a sewage treatment plant is narrow, so by increasing the depth of a biological reaction tank,
Even in the same site area, a deep tank type wastewater treatment apparatus capable of increasing the capacity of a reaction tank for performing an aerobic reaction is used. However, when an aerobic atmosphere is formed in a biological reaction tank by aerating air, the discharge pressure of a normal aeration device (blower) is about 7000 mm water column, and the discharge depth becomes larger due to an increase in water depth. When pressure is required, an aeration device with special specifications is required, and power consumption per aeration amount increases. In a standard sewage treatment plant, the power consumption of the aeration device reaches about half of the power consumption of all facilities, and any further increase in power consumption results in excessive operating costs.

For this reason, the water depth at which the aeration device is provided is 5 m.
It has been proposed to divide the biological reaction tank into upper and lower tanks so that the aerobic biological treatment is performed only in the upper tank of the biological reaction tank having the aeration device. In addition, a swirling channel is formed in the biological reaction tank by a vertically opened partition plate in the biological reaction tank of the deep tank type, and the wastewater is easily swirled by air from the aeration apparatus. It has been proposed to keep the discharge pressure from increasing.

[0005]

Therefore, when the biological reaction tank is made up of two upper and lower tanks, even if the biological reaction tank is made deep to increase the capacity of the reaction tank, it is aerobic only at the upper part of the biological reaction tank. This is disadvantageous in that the capacity of aerobic biological treatment is insufficient due to the inability to carry out biological treatment, and the quality of treated water cannot be improved. Furthermore, the greater the water pressure, the more easily the air aerated in the wastewater is dissolved in the wastewater, and the more efficiently the air is used for aerobic biological treatment. But,
When the biological reaction tank is composed of two upper and lower tanks, the water depth at which the aeration device is installed is within 5 m, so it is difficult to dissolve in wastewater and the efficiency used for biological treatment is low, and fine bubbles that did not dissolve Adhere to the carrier surface in large quantities. This has the disadvantage that the apparent specific gravity of the carrier is reduced, the carrier is densely packed near the liquid surface of the biological reaction tank, and the contact efficiency between the wastewater and the carrier is reduced. In particular, the carrier tends to collect at the outlet of the treated water provided with a screen for separating the carrier, so that the screen is blocked and the flow of the treated water is hindered.

Further, when a partition plate is provided in the biological reaction tank,
On the other hand, the carrier is easily swirled, but the carrier is rubbed against the inner wall of the biological reaction tank by the swirling of the carrier in the biological reaction tank,
There is a disadvantage that the carrier is worn out in a short time. The present invention has been made in view of such circumstances, and even if it is a deep tank type, a large capacity for aerobic biological treatment can be taken, so that the quality of treated water can be improved, and the power consumption required for aeration can be reduced. It is an object of the present invention to provide a carrier expansion phase wastewater treatment apparatus which can reduce the amount of the carrier, does not require a screen for preventing the carrier from flowing out, and can further reduce the wear of the carrier.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a deep biological reactor having an inlet for wastewater and an outlet for a liquid to be treated, An aeration means for forming an aeration gas of air at the top, and a liquid containing oxygen in the aeration gas being supplied to the bottom of the biological reaction tank through a communication pipe communicating the aeration gas and the bottom of the biological reaction tank. An upward flow having a predetermined linear velocity is generated from the bottom of the biological reaction tank to form a carrier expansion phase in which a carrier carrying microorganisms slightly floats in the lower part of the biological reaction tank, and the carrier expansion And a circulating means for forming a stationary aqueous phase in which the linear velocity of the upward flow after passing through the carrier expansion phase is lower than the natural sedimentation velocity of the carrier, between the phase and the exposed gas phase. I do.

According to the present invention, a carrier carrying microorganisms containing nitrifying bacteria is stored in the lower part of the biological reaction tank. Then, the liquid containing sufficient oxygen in the exposed gas phase at the top of the biological reaction tank is circulated to the bottom of the biological reaction tank via the communication pipe, and flows upward from the bottom of the biological reaction tank at a predetermined linear velocity. A swelling phase of the carrier is formed. In addition, by setting the upward flow to the predetermined linear velocity, a stationary water phase of a flow velocity castle where the carrier sufficiently settles naturally is formed in a water area between the carrier expansion phase and the exposed gas phase.

[0009] In the carrier expansion phase, nitrification treatment of mainly ammonia nitrogen in wastewater is performed in an aerobic atmosphere, and the ammonia nitrogen is oxidized to nitrite nitrogen or nitrate nitrogen. Further, in the aerated phase, oxidation treatment of mainly BOD components in wastewater is performed in an aerobic atmosphere, and BO
The D component is oxidatively decomposed. Further, if the treatment liquid treated in the biological reaction tank is discharged from the region of the exposed gas phase, the carrier does not flow out of the biological reaction tank along with the treatment liquid without providing a screen at the outlet.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of a carrier expansion phase wastewater treatment apparatus according to the present invention will be described in detail.
FIG. 1 is a sectional view for explaining a first embodiment of a carrier expansion phase wastewater treatment apparatus of the present invention.

As shown in FIG. 1, in a carrier expansion phase wastewater treatment apparatus 10 according to a first embodiment, wastewater such as sewage mainly flows in through a raw water inflow pipe 12 and a large number of carriers 14 are stored. Biological reaction tank 16 to be used, and biological reaction tank 16
An aeration device 18 for aerating air into the inside and a circulation device 20 for circulating the liquid at the top of the biological reaction tank 16 to the bottom.

The biological reactor 16 has a depth of usually 7 to 15 m.
It is formed in a deep tank. A large number of entrapping immobilized carriers 14 carrying microorganisms including nitrifying bacteria are contained in the biological reaction tank 16.
Alternatively, the binding carrier 14 is stored. The specific gravity of the carrier 14 is set in a range of 1.02 to 1.2, which can be settled in the wastewater in a stationary state and can slightly float by the upward flow formed in the biological reaction tank 16. In addition, carrier 14
Are formed in a dice shape or a spherical shape having a particle size of 0.5 to 5 mm. The raw water supply pipe 12 is connected to a raw water branch pipe 22 in the middle of the raw water supply pipe 12 when raw water containing waste ammonia containing ammoniacal nitrogen and a BOD component flows into the biological reaction tank 16. The raw water branch pipe 22 is connected via a valve 24 to an upper part of a communication pipe 26 described later. Further, a trough 28 is provided near the water surface of the biological reaction tank 16 where the processing liquid treated in the biological reaction tank 16 overflows, and the treated water flowing into the trough 28 is solidified through a treated water pipe 30. Water is sent to the liquid separation tank 32. In the solid-liquid separation tank 32, solids such as activated sludge and the like (which are contained in wastewater and flow into the biological reaction tank) that flowed out with the treated water are settled and separated, and returned to the biological reaction tank 16 via a return pipe 34. It is.

The aeration device 18 includes a plurality of diffuser tubes 36 disposed laterally above the biological reaction tank 16,
The air 40 is constituted by an air pipe 38 for supplying air to the air and a blower (not shown), and the air 40 is upwardly aerated from a number of air nozzles provided in the air diffuser 36. As a result, an exposed gas phase 42, which is a liquid region in which oxygen is sufficiently dissolved, is formed in the upper part of the biological reaction tank 16.

The circulation device 20 mainly includes the biological reaction tank 1
6 is constituted by a communication pipe 26 communicating the upper part (exposure gas phase) and the bottom part, and a circulation pump 44 provided in the middle of the communication pipe 26 and capable of controlling the amount of circulating water. Then, the liquid to which the air 40 has been aerated in the aerated gas phase 42 flows through the communication pipe 26 and is sent to the bottom of the biological reaction tank 16 to form an upward upward flow from the bottom of the biological reaction tank 16. The amount of circulation of the circulation pump 44 is controlled so that the upward flow has a predetermined linear velocity.
As a result, the large number of carriers 14 that have settled at the bottom of the biological reaction tank 16 form a carrier expansion phase 46 that slightly floats due to the upward flow, and a large number of carriers 1 are formed at the bottom of the biological reaction tank 16.
A carrier expansion phase 46, which is a region in which the particles 4 float in an aggregated state, is formed. The expansion height of the carrier expansion phase 46 is preferably not more than 60% of the effective depth of the biological reaction tank 16 (depth in which water is actually stored), and more preferably about 40%. The linear velocity of the upward flow for expanding the carrier is 0.5 to 7 cm / linear velocity when passing through the carrier expansion phase 46.
It is better to maintain the time in seconds, preferably 1 to 6 cm / second. When a carrier having a specific gravity of 1.02 to 1.2 and a particle size of 0.5 to 5 mm is placed in still water, the packing density becomes almost 60 to 70.
%, So if the area where the carrier exists is doubled,
The density of the carrier amounts to 30-35%. The carrier expansion phase 46 includes
60% or less of the effective depth of the biological reaction tank 16, preferably 4%
Since it is 0% or less, the carrier density is 12 to 21% when converted to the entire biological reaction tank 16.

By maintaining the upward flow in this linear velocity range, the stationary water phase, which is a flow velocity castle where the carrier 14 sufficiently settles naturally in the water area between the carrier expansion phase 46 and the exposed gas phase 42. 48 can be formed. That is, the stationary aqueous phase 48
In this case, the space per unit cross-sectional area is increased by the volume of the carrier 14 as compared with the carrier expansion phase 46, and the linear velocity of the upward flow is reduced. It grows and settles naturally.

A discharge port of an air supply pipe 50 is provided on the water suction side of the circulation pump 44 provided in the middle of the communication pipe 26. As a result, the air discharged from the air supply pipe 50 becomes finer in the circulation pump 44 and is easily dissolved in the liquid. Further, a discharge port of the lower air pipe 52 is provided also at the bottom of the biological reaction tank 16. These air supply pipes 5
The 0 and lower air pipes 52 may be used when air shortage occurs only with the aeration device.

Next, the operation of the first embodiment of the carrier expansion phase wastewater treatment apparatus configured as described above will be described. Raw water of wastewater flowing into the biological reaction tank 16 via the raw water supply pipe 12 is sent to the bottom of the biological reaction tank 16 through the communication pipe 26 after the air 40 is sufficiently aerated by the aeration device 18 in the aerated phase. . When the wastewater descends as the downward flow of the communication pipe, a large water pressure is applied to the wastewater, so that the dissolution of air in the wastewater is promoted, and the dissolved oxygen in the wastewater (hereinafter, referred to as “
DO). When the wastewater descends through the communication pipe 26, air is supplied from the air supply pipe 50 to further increase DO.
The concentration can be increased.

Next, the wastewater that has been sufficiently dissolved in the air and sent to the bottom of the biological reaction tank 16 flows upward and rises in the biological reaction tank 16. The linear velocity of the upward flow is 0.5 to 7 cm / in terms of the linear velocity when passing through the carrier expansion phase 46.
Seconds, preferably 1 to 6 cm / sec, so that the carrier expansion phase 4 has a suitable expansion height at the bottom of the biological reactor.
6 is formed, and a stationary water phase 48 is formed in the water body above the expansion phase 46 of the carrier, which is a flow velocity castle where the carrier 14 is sufficiently settled by itself. As a result, some of the carriers 14 that have risen from the carrier expansion phase 46 to the stationary aqueous phase 48 while riding on the upward flow are weakened by the decrease in the linear velocity of the upward flow in the stationary aqueous phase 48. , Spontaneously settle to the region of the carrier expansion phase 46.

That is, the carrier expansion phase wastewater treatment apparatus 1 of the present invention.
0, from the lower part to the upper part of the biological reaction tank 16, the carrier expansion phase 46 in which the carrier 14 and the wastewater are brought into contact with each other in an aerobic atmosphere to perform the nitrification treatment of ammonia nitrogen, and the carrier 14 is allowed to settle naturally to prevent the carrier 14 from flowing out. The following effects can be obtained by forming the aerated gas phase 42 having the stationary aqueous phase 48 for prevention and the aeration device 18 and mainly performing the oxidative decomposition of the BOD component in the wastewater.

An aerobic atmosphere is formed in the upper part (exposure gas phase) and the lower part (expansion phase of the carrier) of the biological reaction tank 16, and
Since the BOD component is mainly decomposed in step 2 and the ammonia nitrogen is mainly nitrified in the carrier expansion phase 46, the capacity for performing aerobic biological treatment even in the deep-type biological reaction tank 16. Can be increased. Therefore, the quality of the treated water can be improved.

Further, the wastewater aerated with the air in the aerated gas phase 42 is circulated to the carrier expansion phase 46 through the communication pipe 26, and the problem that the solubility of air in the wastewater becomes small when aerated at a shallow depth of water is reduced. The problem was solved by promoting the dissolution of air into the liquid by a large water pressure applied when the wastewater descends in the communication pipe 26. Also, a sufficient aerobic atmosphere can be formed in the carrier expansion phase 46 formed in the lower part of the biological reaction tank 16. This allows the aeration device 18 to be disposed above the biological reaction tank 16, for example, at a depth of 7 m or less from the surface of the water, so that a blower having a low discharge pressure can be used, and power consumption is greatly reduced. A significant reduction can be achieved.

The carrier expanded phase 4 in which the carrier 14 is present
Since the amount of dissolved oxygen dissolved in the liquid is higher when aerated in the aerated gas phase 42 without the carrier 14 than in the aerated gas phase 6, the wastewater in which the air is dissolved in the aerated gas phase 42 is circulated to the expanded carrier phase 46. Thus, a sufficient amount of air can be supplied to the carrier expansion phase 46 without aeration in the carrier expansion phase 46. If the amount of air is insufficient, an auxiliary air supply for supplementing only the insufficient amount can be added from the air supply pipe 50 or the lower air pipe 52.

In addition, a carrier expansion phase 46 is formed at the lower part of the biological reaction tank 16, and the treated water is discharged from the region of the aerated gas phase 42 formed at the upper part of the biological reaction tank. Since the stationary aqueous phase 48 is formed between the phases 42, the carrier 14 can be retained in the carrier expanded phase 46 without flowing out of the carrier 14 from the biological reactor 16. Therefore, there is no need for a screen for preventing the carrier from flowing out as in the conventional case.

The carrier 1 forms a carrier expansion phase 46 which does not flow violently in the biological reaction tank 16, thereby forming the carrier 1.
4 does not rub against the inner wall of the biological reactor 16. Therefore, the life of the carrier 14 can be extended.
Next, according to FIG. 2, the carrier expansion phase wastewater treatment apparatus 1 of the present invention
A second embodiment of the present invention will be described. The devices and members described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the second embodiment, an anaerobic tank 5 of the deep tank type having the same depth as the biological reaction tank 16 is provided adjacent to the biological reaction tank 16.
4 is provided to denitrify the nitrate nitrogen generated by the nitrification treatment of the biological reaction tank 16. The anaerobic tank 54 contains microorganisms including denitrifying bacteria, for example, activated sludge, and has a liquid suction slit 56A on the entire bottom surface at the bottom and a liquid outlet 56B on the upper surface. A stirrer 56 is provided. Between the biological reaction tank 16 and the anaerobic tank 54, a water channel 58 having an intake port in the exposed gas phase 48 of the biological reaction tank 16 and opening near the side surface of the underwater agitator 56 disposed in the anaerobic tank 54 is formed. is there.

A communication pipe 26 for communicating the upper part and the lower part of the biological reaction tank 16 is provided upright at the center of the biological reaction tank 16. A water intake 26A is formed in the region of the gaseous phase 42 of the communication pipe 26, and a liquid discharge slit 60 is formed on the entire peripheral surface of the communication pipe drain located near the bottom of the biological reaction tank 16.
A, and an underwater stirrer 60 having a liquid intake 60B on the upper surface is connected thereto. In the middle of the communication pipe 26, the communication pipe 26
An air supply pipe 50 capable of supplying air is provided therein. The underwater stirrer 60 installed in the biological reaction tank 16 is formed wider than the underwater stirrer 56 installed in the anaerobic tank 54, and the wastewater blown out from the underwater stirrer 60 is used for the entire cross section of the biological reaction tank 16. Upflow was set. Thus, the circulation pump in the first embodiment is omitted. The first
Also in the case of the embodiment, an underwater stirrer can be provided instead of the circulation pump.

In the case of the second embodiment, wastewater flows into the anaerobic tank 54 through the raw water supply pipe 12. Furthermore,
A circulation pipe 62 from the upper part of the anaerobic tank 54 to the biological reaction tank 16
Is provided, and a pump 64 is provided in the middle of the circulation pipe 62. Further, the treated water piping 66
Has branched. According to the second embodiment of the present invention,
The same effects as in the first embodiment can be obtained, and nitrate nitrogen generated by the nitrification treatment of the biological reaction tank 16 is surely converted to nitrogen gas by the denitrification treatment in the anaerobic tank 54 and removed. be able to. In addition, the anaerobic tank 54
The BOD component remaining in the biological reaction tank 16 is also reduced by the denitrification treatment in the above.

Next, a third embodiment of the carrier expansion phase wastewater treatment apparatus 10 of the present invention will be described with reference to FIG. The devices and members described in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted. In the third embodiment, a deep tank type anaerobic tank 54 having the same depth as the biological reaction tank 16 is provided beside the biological reaction tank 16, and the liquid to be treated taken from the stationary aqueous phase 48 of the biological reaction tank 16 is provided. Water is supplied to the anaerobic tank 54 and the liquid in the anaerobic tank 54 is supplied to an ejector 68 provided in an air pipe 38 for supplying air to the aeration device 18. In other words, the bottom of the anaerobic tank 54 has a discharge slit 70A for the liquid to be treated on the entire peripheral surface,
An underwater stirrer 70 having a liquid intake port 70B on the upper surface is provided. An intake 72A is provided in the region of the stationary aqueous phase 48 of the biological reaction tank 16, and the intake 7 of the underwater agitator 70 is provided.
A first water supply pipe 72 provided with a discharge port near 0B is provided. Therefore, the underwater stirrer 70 is activated and the water intake 70
When the liquid is sucked from B, a flow from the biological reaction tank 16 to the anaerobic tank 54 is formed in the first water supply pipe 72. This allows the liquid in the stationary aqueous phase 48 with reduced dissolved oxygen to be sent to the anaerobic tank 54, so that the anaerobic atmosphere in the anaerobic tank 54 can be maintained.

When an ejector 68 is provided in the middle of an air pipe 38 for supplying air to the aeration device 18, a second water intake port is provided in the anaerobic tank 54, and a discharge port is communicated with the ejector 68. Is provided. Accordingly, when the air of the aeration device 18 can be used as power for returning the liquid from the anaerobic tank 54 to the biological reaction tank 16, the air is dissolved in the liquid in the anaerobic atmosphere in the anaerobic tank 54 by the ejector 68. After that, the water is sent to the biological reaction tank 16, so that the aerobic atmosphere of the biological reaction tank 16 can be maintained. In this case, since the air nozzle of the air diffuser 36 discharges the liquid in which the air is dissolved, rather than blowing out the air, it is preferable to increase the size of the discharge hole in consideration of the clogging of the air nozzle.

In the third embodiment, the treated water is extracted by connecting the treated water extraction pipe 76 in the middle of the communication pipe 26 without providing a trough through which the treated water overflows. According to the third embodiment of the present invention, the second embodiment of the present invention
The same effect as that of the embodiment can be obtained,
Even if the liquid is circulated between the biological reaction tank 16 and the anaerobic tank 54, the aerobic atmosphere of the biological reaction tank 16 and the anaerobic atmosphere of the anaerobic tank 54 can be maintained.

Next, a fourth embodiment of the carrier expansion phase wastewater treatment apparatus 10 of the present invention will be described with reference to FIG. The fourth embodiment is a modification of the first embodiment, in which the entire biological reaction tank 16 is set to an aerobic atmosphere. still,
The same reference numerals are given to the devices and members described in the first embodiment, and description thereof will be omitted. In the fourth embodiment, instead of omitting the aeration device provided in the aeration gas phase 48 of the biological reaction tank 16, a pressurized air dissolving device 7 is provided in the communication pipe 26.
8 was provided, and the raw water supply pipe 12 was first supplied to the air dissolving device 78 so that the wastewater in which the air was sufficiently dissolved was sent to the bottom of the biological reaction tank 16.

The air dissolving device 78 is a closed pressurized container 80
The compressed air supply pipe 82 and the raw water supply pipe 12 communicate with the pressurized container 80. When the compressed air is bubbled into the wastewater in the pressurized container 80, the internal pressure in the pressurized container 80 increases, and the amount of oxygen dissolved in the wastewater increases. A mesh screen 84 through which the carrier 14 does not pass is provided near the bottom of the biological reaction tank 16.
Are disposed in a direction transverse to the biological reaction tank 16, and form a distribution region 86 of raw water at the bottom of the biological reaction tank 16. The raw water in which oxygen is sufficiently dissolved in the pressurized container 80 is supplied to the distribution area 8
6 and rises as an upward flow distributed over the entire cross section of the biological reaction tank 16 by the screen 84.

A plurality of flow regulating members 88 having a rhombic cross section are provided in the stationary aqueous phase 48 of the biological reaction tank 16.
6 are arranged in a plurality of stages in the horizontal direction. Thereby, even if the carrier 14 which has become light due to the attachment of bubbles and the like rises from the carrier expansion phase 46 to the stationary aqueous phase 48 in the upward flow, the carrier 14
In this case, the linear velocity of the upward flow in the stationary aqueous phase 48 is reduced, and the bubbles are separated from the flow straightening member 88, so that the rising force is reduced. Accordingly, the carrier 14 can be surely spontaneously settled to the region of the carrier expansion phase 46.

A trough 90 for flowing the treated water is provided in the center of the biological reaction tank 16 in the lateral direction. Trough 90
Is formed of an outer frame 92 having an opening 91 at the bottom and an inner frame 94 provided in the outer frame 92 and having upper and lower ends opened, and a treated water pipe 96 is communicated with the inner frame 94. Near the bottom of the opening 91 at the bottom of the trough 90, a baffle member 96 having a rhombic cross section is disposed along the opening 91. As a result, the upward flow rising in the biological reaction tank 16 is prevented by the baffle member 9.
Since it separates to the left and right from 6, the inflow from the opening 91 at the bottom of the trough 90 is prevented. Therefore, a flow is formed in which the liquid flowing into the trough 90 flows out from the opening 91 at the bottom of the trough 90. Even if the carrier 14 flows into the trough 90, the liquid is returned from the opening 91 at the bottom of the trough 90 into the biological reaction tank. be able to.

According to the fourth embodiment of the present invention, the DO concentration in the carrier expansion phase 46 is made higher than in the first embodiment by dissolving the air in the wastewater in a pressurized state. This is particularly effective for wastewater having a low BOD component concentration and a large ammonia nitrogen concentration. next,
A fifth embodiment of the present invention will be described with reference to FIG.

In the fifth embodiment, the stationary aqueous phase 48 with a small amount of oxygen formed in the biological reaction tank 16 is made anaerobic and utilized for denitrification. For this purpose, it is preferable to connect the raw water supply pipe 12 to the communication pipe 26 to supply raw water having a small amount of oxygen to the stationary aqueous phase. That is, in the stationary aqueous phase 48 of the biological reaction tank 16, a plurality of fixed carrier members 100 each having a cross section formed in a U-shape and having microorganisms containing denitrifying bacteria, for example, activated sludge attached thereto, 16 are arranged side by side in the horizontal direction. On the lower side of the fixed carrier member 100, a carbon source which is a nutrient source of the denitrifying bacteria,
For example, a carbon source supply pipe 102 for supplying methanol or the like is provided. In this case, when the concentration of the BOD component in the wastewater is large, as shown by a dotted line in the figure, a bypass pipe 104 connecting a part of the wastewater to the carbon source supply pipe 102 is provided, and The BOD component may be used as a nutrient source for denitrifying bacteria. As a result, the nitrate nitrogen generated by the nitrification treatment of the ammoniacal nitrogen in the carrier expansion phase 46 is transferred to the stationary aqueous phase 4.
At 8, it is denitrified and converted into nitrogen gas and removed from wastewater. By disposing the fixed carrier member 100 in the stationary aqueous phase 48, the sedimentation of the carrier 14 can be promoted in the same manner as in the above-described rectifying member.

The trough 28 and the exposed gas 42 provided near the water surface of the biological reaction tank 16 are separated from the carrier outflow preventing member 10.
6. Partitioned by 6. This carrier outflow prevention member 106 is
It comprises an enclosure 110 surrounding the trough 28 and having an opening 108 at its lower end, and a descending water passage 114 formed by a descending flow forming plate 112 erected between the enclosure 110 and the trough 28. In the vicinity of the lower end of the opening 108 at the lower end of the surrounding frame 110, a baffle member 11 having a triangular cross section is provided.
6 are arranged along the opening 108. As a result, the upward flow rising in the biological reaction tank 16 changes its flow from the baffle member 116 to the right in the drawing, so that the opening 1 at the lower end of the surrounding frame 110 is changed.
08. Thereby, the biological reaction tank 1
The treated water treated in 6 overflows the surrounding frame 110 and flows into the descending flow path 114, and descends as the descending flow path 114 to form a flow that flows out of the opening 108. Even if 14 flows into the enclosure 110, it can be returned into the biological reaction tank 16 through the opening 108 at the lower end of the enclosure 110.

According to the fifth embodiment of the present invention, the first
The same effect as that of the embodiment can be obtained,
The stationary aqueous phase 48 can be effectively used as a denitrification treatment section.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of a carrier expansion phase wastewater treatment apparatus of the present invention. (Embodiment 1) Embodiment 1 is an embodiment carried out using the carrier expansion phase wastewater treatment apparatus shown in FIG.

Secondary sewage water is used as raw water for wastewater,
Treated in a 10 m deep biological reactor. The ammonia nitrogen (NH ₄ -N) concentration of the raw water is 8 to 12 mg / l,
The residence time in the biological reactor was 2 hours. The carrier on which the nitrifying bacteria were immobilized was prepared using a material containing polyethylene glycol as a main component. The carrier used was a 3 mm square die having a specific gravity of 1.08. The volume of the carrier to be added is one of the volume of the biological reaction tank.
0%. At this time, in a stationary state where there is no liquid flow in the biological reaction tank, the height of the carrier expansion phase is 1.5 m. The supply of air to the biological reaction tank is performed only from the aerator installed at a depth of 5 m from the surface of the water, and a part of the liquid in which the air is dissolved in the aerated gas phase is circulated to the bottom of the biological reaction tank, and the biological reaction is performed. An upward flow was formed in the tank. At this time, the NH ₄ —N concentration of the treated water when the linear velocity of the upward flow passing through the carrier expansion phase was changed between 0.2 and 3 cm / sec, and the DO concentration at the top of the carrier expansion phase Are shown in FIGS. 6 and 7, respectively. The DO concentration of the exposed gas was adjusted to 6.5 mg / l.

As can be seen from FIGS. 6 and 7, by setting the linear velocity of the treated water passing through the expanded carrier phase to 0.5 cm / sec or more, preferably 1 cm / sec or more, D
It was possible to supply a liquid having a high O concentration, thereby obtaining treated water having a low NH ₄ —N concentration, that is, treated water having sufficiently advanced nitrification treatment. The line A in FIG. 8 is a result of examining the relationship between the linear velocity of the upward flow passing through the carrier expansion phase and the expansion height of the carrier expansion phase using the above-described carrier having a specific gravity of 1.08 and a size of 3 mm square. It is.

As can be seen from FIG. 8, in the case of the carrier shown by the line A, when the linear velocity becomes 0.3 cm / sec or more, the expansion height becomes 1.5 m in the stationary state (as indicated by the dotted line in FIG. 8). (Indicated height), and the expansion height at a linear velocity of 3 cm / sec reached about 4 m. At this time, no carrier rising into the exposed gas phase was observed. Here, the results obtained by examining the relationship between the linear velocity and the expansion height of the support expansion phase when the specific gravity and size of the support are changed are shown in lines B, C and D in FIG.
Line B is for a carrier having a specific gravity of 1.02 and 3 mm square, line C is for a carrier having a specific gravity of 1.05 and 0.5 mm square, and line D is for a carrier having a specific gravity of 1.2 and 3 mm square. is there. The specific gravity of the carrier was adjusted by changing the specific gravity and the concentration of the specific gravity adjusting agent immobilized simultaneously with the activated sludge. In addition, the shapes are all square (dice-like).

As can be seen from FIG. 8, in the carrier shown by the lines B and C, the expansion height of the carrier expansion phase increases in a sharp curve as the linear velocity of the upward flow increases. This means that when the linear velocity is increased to decrease the NH ₄ —N concentration of the treated water, the amount of the carrier that moves from the carrier expanded phase to the exposed gas phase increases. Therefore, when determining the specific gravity and size of the carrier from the viewpoint of reducing the NH ₄ —N concentration of the treated water and preventing the transfer of the carrier from the carrier expanded phase to the exposed gas phase, when the specific gravity of the carrier is 1.02, Size is 3mm or more, specific gravity is 1.0
In the case of 5, the size needs to be 0.5 mm or more. The carrier formed with the specific gravity and the size as described above has an expansion height of 2 at a linear velocity of 0.5 cm / sec which is the minimum necessary to reduce the NH ₄ —N concentration of the treated water to a satisfactory level. The carrier was maintained at 0.5 m or less, and no carrier was transferred to the exposed gas phase.

In general, the surface area of the carrier has a large effect on the nitrification rate of the carrier. The smaller the carrier, the larger the surface area per unit volume, and the higher the nitrification rate, the larger the size of the carrier. 5 mm is the limit. On the other hand, from the viewpoint of the molding of the carrier, the specific gravity is 1.2
And the carrier having a size of less than 0.5 mm and the carrier having a specific gravity of less than 1.02 have a difficulty in production,
As can be seen from the lines B and C, it is difficult to completely eliminate the carrier rising from the carrier expanded phase to the exposed gas phase.

Further, even if the specific gravity of the carrier is 1.2 and the size is 3 mm, as in the case of the line D, the expansion height is not likely to increase even if the linear speed is increased, the expansion height is higher than 8 cm / sec. Carriers that migrated from the carrier expanded phase to the exposed gas phase with a diameter exceeding 4 m were observed. That is, in the case of a biological reaction tank having a water depth of 10 m, the expansion height of the carrier expansion phase needs to be 6 m or less, preferably 4 m or less. This means
If the expansion height exceeds 6 m, a region of the stationary aqueous phase can hardly be formed between the carrier expansion phase and the exposure gas phase, and the carrier may flow out of the biological reaction tank when the carrier moves from the carrier expansion phase to the exposure gas phase. This is because the property is increased. From this,
The height of the carrier expansion phase is 60% or less, preferably 40% or less of the water depth of the biological reaction tank. When the upper limit of the expansion height of the carrier expansion phase is viewed at the linear velocity of the upward flow, the upper limit of the linear velocity is preferably 7 cm / sec in consideration of safety, and more preferably 6 cm / sec.

Therefore, based on the above results, the carrier has a specific gravity of 1.02 to 1.2 and a size of 0.5 to 5 mm.
It is necessary to The linear velocity of the upward flow is 0.5 to 7 cm / sec, preferably 1 to 6 cm / sec, from the viewpoint of improving the quality of the treated water and preventing the transfer of the carrier from the carrier expansion phase. (Example 2) Example 2 is an example in which wastewater having a high ammonia nitrogen concentration was used using the carrier expansion phase wastewater treatment apparatus shown in FIG.

As raw water used for the wastewater, a sludge treatment liquid discharged in the process of treating excess sludge is used.
The concentration is 100 mg / l and the NH ₄ -N concentration is about 20 mg / l. The residence time in the biological reactor was 7 hours. As in Example 1, the carrier on which the nitrifying bacteria were immobilized was manufactured using a material containing polyethylene glycol as a main component. The carrier is a square type having a specific gravity of 1.2 and a size of 3 mm. The volume of the carrier to be added is 15 times the volume of the biological reactor.
%. At this time, in the stationary state, the height of the carrier expansion phase was 2.2 m. The supply of air to the biological reaction tank is performed only from the aeration device arranged at a depth of 5 m from the water surface, and a part of the liquid in which the air is dissolved in the aerated gas phase is circulated to the bottom of the biological reaction tank, and the biological reaction is performed. An upward flow was formed in the tank. 9 and 10 show the NH ₄ —N concentration of the treated water and the DO concentration at the top of the carrier expansion phase when the linear velocity of the liquid passing through the carrier expansion phase was changed at 2 to 8 cm / sec.
Shown in The DO concentration in the exposed gas phase was kept at 6.5 mg / L.

As can be seen from FIGS. 9 and 10, by setting the linear velocity of the upward flow passing through the carrier expansion phase to 6 cm / sec or more, sufficient DO for nitrifying high-concentration ammonia nitrogen can be obtained. It was possible to supply a liquid having a concentration to the expanded carrier phase, whereby it was possible to obtain treated water in which the nitrification treatment had progressed by about 90%. Moreover, the linear velocity of the upward flow is 7 cm /
If the time is not more than seconds, there is no danger that the carrier having a specific gravity of 1.2 and a size of 3 mm will shift from the carrier expanded phase to the exposed gas phase. (Embodiment 3) Embodiment 3 is an embodiment in which a nitrogen component in sewage is subjected to nitrification and denitrification treatment using the carrier expansion phase wastewater treatment apparatus shown in FIG.

Both the anaerobic tank and the biological reaction tank are 10 m deep
It is. 2. Activated sludge is charged into the anaerobic tank and the residence time is set to 3.
5 hours. The bioreaction phase was filled with a carrier having a specific gravity of 1.08 and a size of 3 mm square in a volume of 10%, and a part of the liquid in which oxygen was dissolved in the exposed gas phase was led to the lower side of the carrier expansion phase. The residence time of the carrier reaction phase was 2.5 hours. The linear velocity of the upward flow passing through the carrier expansion phase is 2 cm / sec, and the liquid to be treated in the stationary aqueous phase is supplied to the anaerobic tank, and the amount of the supplied water is three times the raw water amount of the wastewater supplied to the anaerobic tank. Amount. In addition, a part of the liquid in the anaerobic tank was sent to an ejector provided in an air pipe of the aerator, and returned from the aerator to the biological reaction tank together with the air. The liquid flowing out of the exposed gas phase is guided to a solid-liquid separation tank (not shown), and the activated sludge is separated to obtain treated water. Part of the settled sludge was returned to the anaerobic tank. Water temperature varied between 15 and 25 ° C.

FIG. 11 shows the nitrogen (TN) load and the treated water T
The relationship between -N and the NH ₄ -N concentration of the treated water is shown. The nitrogen load was indicated per total volume of the anaerobic tank and the biological reaction tank.
Nitrogen load up to 0.15kg / m ³ / day, treated water TN
Was less than 10 mg / L. The NH ₄ -N concentration of the treated water always satisfies 1 mg / L or less,
Stable nitrification performance in the biological reactor was confirmed. (Embodiment 4) Embodiment 4 is an embodiment in which sewage secondary treatment water is subjected to nitrification and denitrification treatment using the carrier expansion phase wastewater treatment apparatus shown in FIG.

The NH ₄ —N concentration of the raw water of the wastewater is 8 to 12
mg / L, and the residence time was 4 hours in a 10 m biological reaction tank. The carrier has a specific gravity of 1.05 and a size of 3m
m is a square shape. The volume of the carrier to be added was 15% based on the total volume of the biological reactor, and was about 45% per the nitrification section described later. The supply of air to the biological reaction tank was performed from an aeration device provided at a depth of 3.3 m from the water surface, and a part of the liquid in which air was dissolved in the aerated gas phase was guided to the lower side of the carrier expansion phase. The linear velocity of the upward flow passing through the carrier expansion phase was 0.5 cm / sec.

In addition, a stationary carrier member having microorganisms containing denitrifying bacteria attached to the stationary aqueous phase is provided, and methanol as a carbon source is supplied from a carbon source supply pipe provided at a depth of 6 m from the water surface. Feed to the stationary aqueous phase. The concentration of microorganisms adhering to the fixed carrier member was about 20,000 mg / L per volume of the denitrification treatment section described later, and the concentration was 6600 mg / L with respect to the total volume of the biological reaction tank.

Thus, the biological reaction tank is composed of a nitrification treatment section of the carrier expansion phase, a denitrification treatment section of the stationary aqueous phase, and an aerobic treatment section of the aerated gas phase from the bottom, and the volume ratio of each section is 1: It was set to 1: 1.
FIG. 12 shows the relationship between the amount of methanol added (concentration per raw water) and the quality of treated water. As can be seen from FIG. 12, when the amount of methanol added is 25 to 30 mg / L, NH ₄ —N
Good results were obtained in which both the concentration and the NO ₃ -N concentration were 1 mg / L or less. (Embodiment 5) In Embodiment 5, leachate generated from a landfill of municipal garbage is treated using the carrier expansion phase wastewater treatment apparatus described in Embodiment 4. Leachate NH ₄ -N
Although the concentration is as high as 500-600 mg / L, BO
The concentration of the D component was 200 mg / L, and the BOD / N ratio used was as low as 0.2 to 0.4. For this reason, methanol was added from the carbon source supply pipe.

The nitrogen load of each section was 0.9
kg-N / m ³ · day, a result of the operation at a water temperature of 12 ° C, can the NH ₄ -N concentration in the treated water below 2 mg / L, also the total nitrogen concentration (T-N) below 50 mg / L, A high nitrogen removal rate of 90% or more could be obtained.

[0055]

As described above, according to the carrier expansion phase wastewater treatment apparatus of the present invention, the following effects can be obtained because the apparatus is configured as described above. Even a deep-type biological reaction tank can have a large capacity for performing aerobic biological treatment. Therefore, the quality of the treated water can be improved.

Further, an aeration device having a low discharge pressure can be used, and the power consumption can be greatly reduced. In addition, since the carrier expansion phase is formed at the lower part of the biological reaction tank, and a stationary aqueous phase is formed between the carrier expansion phase and the exposed gas phase, the carrier is maintained in the carrier expansion phase without flowing out of the carrier from the biological reaction tank. be able to. Therefore, there is no need for a screen for preventing the carrier from flowing out at the outlet of the treated water as in the prior art.

The life of the carrier can be prolonged by forming a carrier expansion phase in which the carrier does not violently swirl in the biological reaction tank.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a first embodiment of a carrier expansion phase wastewater treatment apparatus of the present invention.

FIG. 2 is a cross-sectional view for explaining a second embodiment of the carrier expansion phase wastewater treatment apparatus of the present invention.

FIG. 3 is a cross-sectional view illustrating a third embodiment of the carrier expansion phase wastewater treatment apparatus of the present invention.

FIG. 4 is a cross-sectional view illustrating a fourth embodiment of the carrier expansion phase wastewater treatment apparatus of the present invention.

FIG. 5 is a sectional view for explaining a fifth embodiment of the carrier expansion phase wastewater treatment apparatus of the present invention.

FIG. 6 is an explanatory diagram illustrating the relationship between the linear velocity of upward flow and the concentration of ammonia nitrogen in treated water.

FIG. 7 is an explanatory diagram for explaining a relationship between a linear velocity of an upward flow and a dissolved oxygen (DO) concentration in an upper part of a carrier expansion phase of treated water.

FIG. 8 is an explanatory diagram for explaining the relationship between the linear velocity of the upward flow and the expansion height of the carrier expansion phase when the specific gravity and size of the carrier are changed.

FIG. 9 is an explanatory diagram for explaining the relationship between the linear velocity of upward flow and the ammonia nitrogen concentration of treated water when a high concentration of ammonia nitrogen is treating wastewater.

FIG. 10 is an explanatory diagram for explaining the relationship between the linear velocity of upward flow and the concentration of dissolved oxygen in the upper part of the carrier expansion phase of treated water when a high concentration of ammonia nitrogen is treating wastewater.

FIG. 11 is an explanatory diagram for explaining the relationship between the nitrogen load, the total nitrogen concentration and the ammonia nitrogen concentration of the treated water.

FIG. 12 is an explanatory diagram illustrating the relationship between the amount of methanol added and the total nitrogen concentration of treated water when nitrification and denitrification treatment is performed by the carrier expansion phase wastewater treatment device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Carrier expansion phase wastewater treatment apparatus 12 ... Raw water supply pipe 14 ... Carrier 16 ... Biological reaction tank 18 ... Aeration apparatus 20 ... Circulation apparatus 26 ... Communication pipe 28, 90 ... Trough 40 ... Bubbles 42 ... Exposure gas phase 44 ... Circulation pump 46 ... carrier expansion phase 48 ... stationary aqueous phase 54 ... anaerobic tank 56, 60, 70 ... underwater stirrer 68 ... ejector 88 ... rectifying member 96, 116 ... baffle member 100 ... fixed carrier member 106 ... carrier outflow prevention member

Continuation of the front page (72) Inventor Yuki Nakamura 1-1-1 Uchikanda, Chiyoda-ku, Tokyo Inside the Hitachi Plant Construction Co., Ltd. (72) Inventor Masataka Kasai 1-11-1 Uchikanda, Chiyoda-ku, Tokyo Sun Standing Plant Construction Co., Ltd.

Claims (8)

[Claims] A deep-water type biological reaction tank having an inlet for wastewater and an outlet for liquid to be treated; aeration means for forming an aeration phase of air in an upper part of the biological reaction tank; A liquid containing oxygen in the exposed gas phase is fed to the bottom of the biological reaction tank through a communication pipe that communicates the phase with the bottom of the biological reaction tank, and a predetermined linear velocity is supplied from the bottom in the biological reaction tank. By generating an upward flow having, a carrier expansion phase in which the carrier carrying the microorganisms slightly floats at the lower part of the biological reaction tank, and passes through the carrier expansion phase between the carrier expansion phase and the exposed gas phase. And a circulating means for forming a stationary aqueous phase in which the linear velocity of the upward flow after the separation is lower than the natural sedimentation velocity of the carrier. 2. An anaerobic tank having activated sludge is provided adjacent to the biological reaction tank, and a liquid is circulated between the biological reaction tank and the anaerobic tank. Carrier expansion phase wastewater treatment equipment. 3. An anaerobic tank having activated sludge is provided adjacent to the biological reaction tank, a liquid taken from a stationary aqueous phase of the biological reaction tank is supplied to the anaerobic tank, and a liquid from the anaerobic tank is supplied to the anaerobic tank. The water is supplied to an ejector provided in an air pipe for supplying air to the aeration unit.
Expansion phase wastewater treatment equipment. 4. A supply means for supplying a carbon source to said denitrifying bacteria in addition to providing a fixed carrier member to which microorganisms containing denitrifying bacteria are attached in a stationary aqueous phase in said biological reaction tank. The carrier expansion phase wastewater treatment apparatus according to claim 1, wherein 5. The predetermined linear velocity of the upward flow is 0.5 to 7 cm at a linear velocity when passing through the carrier expansion area.
/ Sec.
3 or 4 carrier expansion phase wastewater treatment apparatus. 6. The carrier according to claim 1, wherein the specific gravity is 1.02 to 1.2 and the particle size is 0.5 to 5 mm.
2, 3, 4 or 5 carrier expansion phase wastewater treatment equipment. 7. The depth of the biological reaction tank is 7 to 15 m, and the depth of the carrier expansion phase is 60% of the water depth of the biological reaction tank.
Claims 1, 2, 3, 4, 5 characterized in that:
Or the carrier expansion phase wastewater treatment apparatus of 6. 8. An underwater stirrer for sucking a liquid in the communication pipe and blowing it out around the lower end of the communication pipe is provided. 6. The carrier expansion phase wastewater treatment apparatus according to 6 or 7.