JPH05169090A - Device for supplying nitrification bacteria in biological activated carbon treatment tower - Google Patents

Abstract

PURPOSE:To provide the device which enables early starting of a biological activated carbon treatment tower utilized for purifying treatment of water and also performs excellent treatment in removal performance of trace organic substance or the like and removal performance of ammoniac nitrogen. CONSTITUTION:A biological activated carbon treatment tower 2 packed with a granular activated carbon 3 is provided. Separately a nitrification bacterial culture tank 4 is provided. Moreover a mechanism for supplying oxygen to nitrification bacteria 6 in the tank and an agitating mechanism are equipped in the nitrification bacteria culture tank 4. Furthermore a device for supplying nitrification bacteria is equipped with both a return system 11 for feeding one part of granular activated carbon 3 to the culture tank 4 from the treatment tower 2 and a supply system 12 for feeding granular activated carbon 3 deposited with cultured nitrification bacteria 6 to the treatment tower 2 from the culture tank 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for supplying nitrifying bacteria to a biological activated carbon treatment tower (including a biological filtration treatment tower) used for purification of tap water.

[0002]

2. Description of the Related Art Generally, when purifying raw water or secondary sewage treated water taken from rivers, etc., first, a flocculant is injected and mixed in raw water in a flocculation sedimentation tank, and suspended substances in raw water are treated by stirring and retaining. (Sand, clay, algae, and other organic substances) are aggregated, precipitated, and separated. This process incorporates algae treatment and chlorine treatment for the purpose of removing chromaticity components such as iron and manganese. Particularly in the suburbs of large cities, rivers are highly polluted, so the content of ammonia and chromaticity components including humic substances, which are precursors of the carcinogenic THM (trihalomethane), is high. React to produce chloramine and consume more chlorine than necessary, resulting in a high chlorine injection rate and TH
Increases the ability to generate M (THMFP).

From such a background, in recent years, a method of incorporating an advanced water purification system into the water purification process has been used for the purpose of removing the above-mentioned substances. This advanced water purification method includes ozone treatment and biological activated carbon treatment. For example, as an alternative to chlorine treatment, ozone treatment is performed by an ozone treatment tower, and further a chromaticity component is removed by an activated carbon treatment tower or biological filtration tower. After that, it is filtered with a sand filter, etc. and sent to a water purification tank.

The granular activated carbon packed in the activated carbon treatment tower is
Microorganisms such as nitrifying bacteria are propagated on the surface, and not only the adsorption and removal of trace organic substances in the inflowing water,
It is also possible to remove ammonia. Further, by performing the ozone treatment before the biological activated carbon treatment, it is possible to improve the tolerance against load fluctuation and the life of the activated carbon.

[0005]

In the biological activated carbon treatment used in the above advanced water treatment system, it takes a long time to start up the activated carbon treatment tower. That is, at the time of starting the operation of the activated carbon treatment tower or restarting the operation after exchanging the activated carbon, it is necessary to perform the start-up operation in order to grow the microorganisms on the surface of the activated carbon and stabilize the biota.
And when the growth rate of microorganisms on the surface of activated carbon is decreased, in other words, when the activity of nitrifying bacteria is decreased,
In addition to the extension of the startup time, there is a problem that the removal rate of ammonia by microorganisms is significantly reduced.

It is known that the activity of the above nitrifying bacteria is also affected by the water temperature, and the water temperature is 1 when compared to the high water temperature in summer.
The activity of nitrifying bacteria decreases in the winter when the temperature falls below 0 ° C, and a phenomenon occurs in which the concentration of ammonia increases conversely as the amount of water in rivers decreases. In particular, the growth rate of nitrifying bacteria is considerably slower than that of other microorganisms that remove organic substances, etc., and it is necessary for at least about 1 to 3 days.
When the water temperature is 10 ° C., the time required for the stationary treatment may be more than twice as long as the time required for the steady ammonia removal process by nitrifying bacteria at the temperature of ℃. There is a problem that the processing efficiency is significantly deteriorated.

Further, the activated carbon having a biota formed on the surface is
There is a possibility that the biota may impair the adsorption and removal performance of trace organic substances, and it is necessary to take this into consideration when performing treatment with biological activated carbon.

In view of these problems, the present invention provides an apparatus which enables early startup of a biological activated carbon treatment tower, and which is capable of treating both trace organic substances and ammonia nitrogen with excellent removal performance. The purpose is.

[0009]

In order to achieve the above object, first, according to claim 1, a nitrifying bacteria culture tank is provided separately from a biological activated carbon treatment tower filled with granular activated carbon, and the nitrification is performed. The bacterial culture tank is provided with an oxygen supply mechanism and a stirring mechanism for nitrifying bacteria in the tank, and further, a return system for sending a part of the granular activated carbon from the biological activated carbon treatment tower to the nitrifying bacteria culture tank, and from the nitrifying bacteria culture tank A nitrifying bacteria supply device for a biological activated carbon treatment tower is provided with a supply system for feeding granular activated carbon to which the cultured nitrifying bacteria adhered to the biological activated carbon treatment tower. Further, according to claim 2, a biological filtration treatment tower filled with a biological filter medium having high microbial activity is used instead of the biological activated carbon treatment tower, and according to claim 3, the nitrifying bacteria culture tank is maintained at 20 ° C to 30 ° C. Placed in a constant temperature bath maintained in the range of ° C, further according to claim 4, in the nitrifying bacteria culture tank,
A raw water supply unit for supplying raw water containing ammonia is provided at regular intervals or continuously.

[0010]

According to this structure, during normal raw water treatment, the raw water is purified by the granular activated carbon or the biological filter medium in the biological activated carbon treatment tower or the biological filtration treatment tower, and at the same time, the granular activated carbon or the surface of the biological filter medium is propagated. Due to the action of nitrifying bacteria, not only the trace organic substances are adsorbed and removed, but also ammonia is removed.

Then, when a part of the granular activated carbon or the biological filter medium with the nitrifying bacteria adhered to the nitrifying bacteria culture tank is returned from the biological activated carbon treatment tower or the biological filtration treatment tower through the return system,
Due to aeration and agitation in the nitrifying bacteria culture tank, oxygen is supplied to the nitrifying bacteria which are aerobic bacteria and the nitrifying bacteria grow, and a large amount of the grown nitrifying bacteria adhere to the surface of the granular activated carbon or the biological filter medium. At this time, by supplying raw water containing ammonia from the raw water supply unit at regular intervals or continuously, the growth efficiency of nitrifying bacteria is improved.

Next, the activated carbon surface in the biological activated carbon treatment tower or the biological filtration treatment tower is returned to the biological activated carbon treatment tower or the biological filtration treatment tower by returning the granular activated carbon or the biological filtration medium having a large amount of nitrifying bacteria attached thereto through the supply system. The amount of attached microorganisms increases, and the activity of nitrifying bacteria increases, and as a result, the removal rate of ammonia in raw water is increased.

[0013]

EXAMPLES An example of a nitrifying bacteria supply device for a biological activated carbon treatment tower according to the present invention will be described below. In the schematic view of this embodiment shown in FIG. 1, 1 is a raw water, 2 is a biological activated carbon treatment tower into which the raw water 1 is introduced, and this biological activated carbon treatment tower 2
Granular activated carbon 3 is filled therein. It is also possible to use a biological filtration treatment tower in place of the biological activated carbon treatment tower 2, and in this case, a biological filter medium having a high microbial activity is filled in the biological filtration treatment tower.

On the other hand, 4 is a nitrifying bacteria culture tank which is arranged separately from the biological activated carbon treatment tower 2, and this nitrifying bacteria culture tank 4 is entirely arranged in a constant temperature tank 5. The nitrifying bacteria culture tank 4 is kept in the range of 20 to 30 ° C. by the constant temperature tank 5.

Into the nitrifying bacteria culture tank 4, nitrifying bacteria 6 adhering to the activated carbon or the biological filter medium are introduced and oxygen is supplied to the nitrifying bacteria which are aerobic bacteria. An air diffuser 7 is arranged. Air is sent to the air diffuser 7 from a blower 8 provided outside. Reference numeral 9 denotes a raw water supply unit for supplying raw water containing ammonia to the nitrifying bacteria culture tank 4 at regular intervals or continuously.

A nitrifying bacteria supply device 10 is constituted by the above-mentioned nitrifying bacteria culture tank 4, constant temperature tank 5, air diffuser 7 and blower 8.

Numeral 11 is a return system for feeding the granular activated carbon 3 or a part of the biological filter medium from the biological activated carbon treatment tower 2 to the nitrifying bacteria culture tank 4, and 12 is the reverse from the nitrifying bacteria culture tank 4 to the biological activated carbon treatment tower 2. It is a supply system for feeding the granular activated carbon 3 in which the nitrifying bacteria have been cultured or the biological filter medium. This supply system 12
A pump 13 and a flow rate adjusting valve 14 are provided in the middle of the area. Reference numeral 15 is a backwash drain, and 16 is a treated water outlet.

According to this structure, when the normal raw water treatment is carried out, the raw water 1 flows into the biological activated carbon treatment tower 2 or a biological filtration treatment tower (not shown) and is purified by the granular activated carbon 3 or the biological filter medium. At the same time, by the action of the granular activated carbon 3 and the nitrifying bacteria that propagate on the surface of the biological filter medium, not only the trace organic substances are adsorbed and removed, but also ammonia is removed. In addition, the life of the granular activated carbon 3 is improved by performing the ozone treatment before the biological activated carbon treatment.

On the other hand, in order to enhance the treatment capacity of the biological activated carbon treatment tower 2 or the biological filtration treatment tower, the nitrifying bacteria are transferred from the biological activated carbon treatment tower 2 or the biological filtration treatment tower to the nitrifying bacteria culture tank 4 through the return system 11. The granular activated carbon 3 or the part of the biological filter material attached with is returned. This nitrifying bacteria culture tank 4 is kept in a temperature range of 20 to 30 ° C. by a constant temperature tank 5.
Furthermore, by supplying air from the blower 8 arranged outside to the air diffuser 7 arranged at the inner bottom of the nitrifying bacteria culture tank, aeration and agitation are performed in the nitrifying bacteria culture tank 4, and aerobic bacteria are generated. Oxygen is supplied to a certain nitrifying bacterium 6, and the nitrifying bacterium 6 grows.

As shown in the schematic view of FIG. 2, a large amount of the grown nitrifying bacteria 6, 6 adhere to the surface of the granular activated carbon 3 or the biological filter medium (not shown) by the aeration and stirring. At this time, by supplying the raw water containing ammonia from the raw water supply unit 9 at regular intervals or continuously, the growth efficiency of the nitrifying bacteria 6 is improved.

Next, while operating the pump 13 provided in the supply system 12, by appropriately opening the flow rate adjusting valve 14,
Since the granular activated carbon 3 or the biological filter medium having a large amount of nitrifying bacteria 6 attached thereto returns to the biological activated carbon treatment tower 2 or the biological filtration treatment tower, the amount of microorganisms attached on the surface of the activated carbon in the biological activated carbon treatment tower 2 or the biological filtration treatment tower is As a result, the activity of nitrifying bacteria is improved, and as a result, the removal rate of ammonia in the raw water 1 can be increased.

The activity of the nitrifying bacteria 6 is also affected by the water temperature,
Since the activity of the nitrifying bacteria 6 tends to decrease in the winter when the water temperature falls below 10 ° C. as compared to the high water temperature in the summer, it is effective to use the nitrifying bacteria supply device 10 according to the present embodiment in the winter. Along with this, the time required to achieve the regular ammonia removal treatment by the nitrifying bacteria 6 when the water temperature drops is shortened. Then, the treated water flows out from the treated water outlet 16.

Further, when the operation of the biological activated carbon treatment tower 2 is started,
Alternatively, when the operation is restarted after the activated carbon is exchanged, the nitrifying bacteria 6 are supplied from the nitrifying bacteria supply device 10 even when the microorganisms are grown on the surface of the activated carbon and the startup operation for stabilizing the biota is performed. As a result, the growth rate of microorganisms is accelerated, and the start-up operation time can be shortened.

FIG. 3 is a schematic diagram showing the change in the thickness of the nitrifying bacteria layer in the biological activated carbon treatment tower 2, wherein A layer is the nitrifying bacteria layer and B layer is the THM-producing ability removing layer. As described above, when part of the granular activated carbon 3 having nitrifying bacteria adhered to the nitrifying bacteria culture tank 4 is returned from the biological activated carbon treatment tower 2 to the nitrifying bacteria culture tank 4, the thickness of the layer A, which is the nitrifying bacteria layer, becomes small, The amount of raw water that flows in is increased by that amount, and by increasing the thickness of the nitrifying bacteria layer A, the ammonia removal rate is increased by the activity of the nitrifying bacteria as described above. Therefore, in consideration of the state of raw water 1 and the treatment capacity of the biological activated carbon treatment tower 2, the granular activated carbon 2 for the nitrifying bacteria supply device 10
Alternatively, by determining the returned amount of the biological filter medium and the supplied amount of the nitrifying bacteria from the nitrifying bacteria culture tank 4 to the biological activated carbon treatment tower 2, it is possible to cope with the load fluctuation of the ammonia concentration.

Further, as shown in FIG. 3, as a result of monitoring the relationship between the ammonia removing ability and the THMFP removing ability,
It was confirmed that ammonia was mainly removed in the upper layer of the treatment tower, and THMFP was mainly removed from the middle layer to the lower layer of the treatment tower.

[0026]

As described above, according to the present invention,
The nitrifying bacteria grow in the nitrifying bacteria culture tank by returning part of the granular activated carbon or the biological filter material on which the nitrifying bacteria adhere to the nitrifying bacteria culture tank from the biological activated carbon treatment tower or the biological filtration processing tower through the return system. Therefore, by returning the granular activated carbon or biological filter medium with a large amount of nitrifying bacteria attached to the biological activated carbon treatment tower or the biological filtration treatment tower through the supply system, the microorganisms on the activated carbon surface in the biological activated carbon treatment tower or the biological filtration treatment tower are The activity of nitrifying bacteria is improved by increasing the adhered amount, and the ammonia removal rate of raw water can be increased. In particular, the activity of nitrifying bacteria is likely to decrease in the winter when the water temperature is lower than when the water temperature is high in the summer, so it is effective to apply the present invention in the winter, and accordingly, the steady state by the nitrifying bacteria at the time when the water temperature decreases It is possible to shorten the time for achieving the effective ammonia removal treatment.

Further, when the granular activated carbon or the filter medium to which the nitrifying bacteria adhere is erroneously discharged during backwashing of the biological activated carbon treatment tower or the biological filtration treatment tower, the nitrifying bacteria supply device according to the present invention can be used in a timely manner. By doing so, it is possible to immediately replenish the treatment tower with nitrifying bacteria and prevent a decrease in the ammonia removal rate.

Further, at the time of starting the operation of the biological activated carbon treatment tower or restarting the operation after exchanging the activated carbon, it is possible to accelerate the growth rate of microorganisms on the surface of the activated carbon, which makes it possible to shorten the startup operation time. In addition, an apparatus is provided that can perform a treatment that is excellent in the removal performance of trace organic substances and the like and the removal performance of ammonia nitrogen.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a nitrifying bacteria supply device for a biological activated carbon treatment tower according to the present invention.

FIG. 2 is a schematic diagram showing a state of adhesion of nitrifying bacteria to granular activated carbon.

FIG. 3 is a schematic diagram showing changes in the thickness of a nitrifying bacteria layer in a biological activated carbon treatment tower.

[Explanation of symbols]

1 ... Raw water, 2 ... Biological activated carbon treatment tower, 3 ... Granular activated carbon, 4
... Nitrifying bacteria culture tank, 5 ... Constant temperature tank, 6 ... Nitrifying bacteria, 7 ... Air diffuser, 8 ... Blower, 9 ... Raw water supply unit, 10 ... Nitrifying bacteria supply device, 11 ... Return system, 12 ... Supply system, 13 ... Pump, 14
... Flow rate adjusting valve, 15 ... Backwash drain port, 16 ... Treated water outlet.

Claims (4)

[Claims] 1. A nitrifying bacteria culture tank is provided separately from the biological activated carbon treatment tower filled with granular activated carbon, and the nitrifying bacteria culture tank is provided with an oxygen supply mechanism and a stirring mechanism for the nitrifying bacteria in the tank. A supply system that deploys and sends a part of the granular activated carbon from the biological activated carbon treatment tower to the nitrifying bacteria culture tank and a granular activated carbon to which the cultured nitrifying bacteria are attached from the nitrification bacteria culture tank to the biological activated carbon treatment tower A system for supplying nitrifying bacteria to a biological activated carbon treatment tower, comprising: 2. The nitrifying bacteria supply device for a biological activated carbon treatment tower according to claim 1, wherein a biological filtration treatment tower filled with a biological filter medium having a high microbial activity is used in place of the biological activated carbon treatment tower. 3. The nitrifying bacteria supply device for a biological activated carbon treatment tower according to claim 1, wherein the nitrifying bacteria culture tank is arranged in a constant temperature tank maintained in a range of 20 ° C. to 30 ° C. 4. The nitrifying bacteria supply device for a biological activated carbon treatment tower according to claim 1, wherein the nitrifying bacteria culture tank is provided with a raw water supply unit for supplying raw water containing ammonia at regular intervals or continuously.