JPH1076284A - Water purifying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water purifying apparatus which indicates good performance for removing nasty odors (mold odor, etc.) in raw water for tap water, trihalomethane precursors, etc., can use active carbon effectively, and has only a small number of columns and tanks. SOLUTION: A purified water treatment apparatus is equipped with a biological contact filtration tank 10 having a biological filtration layer 12, air spouting pipe 15 to aerate the layer 12, etc., a biological contact filtration treatment water storage tank 16 for storing biological contact filtration treatment water, and a communication valve 17 for making the tank 10 and the tank 16 communicate with each other through the bottom parts. The raw water is introduced from a raw water supply pipe 14 into the tank 10 and subjected to biological filtration treatment, and dirty substances to be mixed into the biological filtration treatment water are removed by active carbon in the tank 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water purification treatment apparatus provided with a powdered activated carbon adsorption treatment means used for removing off-flavors (mould odor, etc.) in raw tap water and pollutants such as trihalomethane precursors. In addition, the biological contact filtration treatment water storage tank can also be used as a powdered activated carbon adsorption treatment tank, and at the same time as the backwashing, it is performed with the biological contact filtration treatment water into which the powdered activated carbon has been injected, and the powdered activated carbon is regenerated. The present invention relates to a water purification device capable of effectively using activated carbon.

[0002]

2. Description of the Related Art In recent years, in tap water, the tendency of generation of off-flavor due to deterioration of water source water quality is remarkable, and certain algae (Anabaena
macrospora, Phormidium tenue, Oscillatoria tenu
is, etc.), the problem of unpleasant taste of tap water due to the odorous substances produced by the odorous substances is becoming apparent. In addition, the contamination of tap water by organic substances, such as trihalomethane precursors, is becoming more serious.In the existing water purification process, chlorine used for sterilization and disinfection reacts with the trihalomethane precursor to convert trihalomethane. There is a concern that tap water may be contaminated by such substances. A technique for addressing these problems is a so-called advanced water purification technique, and powdered activated carbon adsorption processing is one of the advanced water purification techniques.

In the powdered activated carbon adsorption treatment, as shown in FIG. 3, raw water is introduced into a powdered activated carbon contact tank 1, and powdered activated carbon is injected according to the concentration of a substance to be removed contained in the raw water for a predetermined time. This is a process in which the substance to be removed dissolved in the raw water is stirred and retained, adsorbed on the powdered activated carbon, sent to the coagulation sedimentation tank 2, passed through the sand filtration tank 3, and removed from the raw water. The substances to be removed include off-flavors (such as musty odor) and trihalomethane precursors. The activated carbon powder to which the substance to be removed is adsorbed is removed by a solid-liquid separation process such as a coagulation sedimentation tank 2 and a sand filtration tank 3 at the subsequent stage to obtain treated water. In this powdered activated carbon adsorption treatment, since the treatment capacity is controlled by controlling the amount of powdered activated carbon to be injected, it is an effective treatment method when the concentration of pollutants in the water to be treated changes with the season. However, in this powdered activated carbon adsorption treatment method,
Some soluble substances such as ammonia nitrogen and suspended substances such as algae cannot be removed.

Further, in the solid-liquid separation process of the subsequent coagulation sedimentation tank 2, sand filtration tank 3, etc., it is necessary to remove powdered activated carbon, and therefore, the injection amount of powdered activated carbon has an upper limit depending on the processing capacity. If the amount of the substance to be removed contained in the water to be treated exceeds the powdered activated carbon adsorption treatment capacity, the polluted substance will not be completely removed by the powdered activated carbon adsorption treatment but will remain. Was sometimes a problem. In addition, when a certain type of algae is generated in large quantities, the subsequent coagulation and sedimentation process becomes impossible to coagulate, and in particular, the removal of suspended solids in the subsequent solid-liquid separation process becomes insufficient, The solid-liquid separation process may become inoperable.

Further, powdered activated carbon is expensive depending on its type. In the water treatment using powdered activated carbon, if the powdered activated carbon cannot be used effectively, the cost of the treated water will rise and the economy will be lost. Therefore, in order to effectively use the powdered activated carbon, it is necessary to maintain a sufficient contact time with the powdered activated carbon. Therefore, there was a problem that the powdered activated carbon contact tank was enlarged.

On the other hand, biological treatment facilities and the like are used for advanced treatment for removing ammonia nitrogen, off-flavor (mold odor, etc.), algae and the like. Biological treatment has the advantage of low cost and the advantage that even when a high concentration of pollutants flows in, a removal rate of approximately 70% can be obtained in the case of 2-methylisoborneol, a kind of odorant, for example. There is. However, in the case of biological treatment, there is a problem that it is difficult to remove 100% of off-flavors and trihalomethane precursors.

As a treatment method for sufficiently removing ammonia nitrogen, off-flavors, algae, and trihalomethane precursors and suppressing an increase in operating costs due to the addition of powdered activated carbon as much as possible, a powdered activated carbon treatment is conducted in the first stage, and a biological treatment is conducted in the second stage. There was a method of performing a filtration treatment. As shown in FIG. 4, this treatment method includes a powdered activated carbon adsorption treatment facility including a powdered activated carbon storage tank 4, a powdered activated carbon supply pump 5, a powdered activated carbon contact tank 1, and the like, a biological contact filtration tank 7, and a biological water for backwashing water storage. Contact filtered water storage tank 8, backwashing water supply equipment 9, and backwashing blower 6
Since it is necessary to install a biological contact filtration equipment comprising in series and to remove the powdered activated carbon by a solid-liquid separation process comprising a coagulation sedimentation tank 2, a sand filtration tank 3, etc.
There was a problem that many tower tanks were required.

The present invention has been made in order to solve the above-mentioned problems, and has an objectionable odor (such as moldy odor) in tap water.
It is an object of the present invention to provide a water purification treatment device that exhibits excellent treatment performance for removing pollutants such as trihalomethane precursors, enables effective use of activated carbon, and requires fewer towers.

[0009]

Means for Solving the Problems The present invention has been made to achieve the above object, and the invention according to claim 1 is a water purification treatment apparatus for performing biological filtration, wherein the biological filtration layer and the biological filter are provided. A biological contact filtration tank provided with an air blowing pipe for aerating the filtration layer, a biological contact filtration treatment water storage tank provided with a powdered activated carbon injection pipe for injecting powdered activated carbon into the biological contact filtration treatment water, and aeration of the biological filtration layer And a back washing means for flowing the biological contact filtration water into which the powdered activated carbon in the biological contact filtration water storage tank is injected into the biological contact filtration tank to wash the biological filtration layer. It is a water purification device.

The invention according to claim 2 is a water purification treatment apparatus for performing biological filtration, wherein a biological contact filtration tank and a biological contact filtration treatment water storage tank for storing biological contact filtration treatment water are arranged. A biological contact filtration tank, a biological filtration layer filled on a support layer provided in the biological contact filtration tank, an air blowing pipe provided on the support layer and performing aeration when the biological filtration layer is washed, A washing drain valve for discharging water, an intermediate drain valve for lowering the water level in the biological contact filtration tank at the time of washing, a powdered activated carbon injection pipe disposed at the bottom of the biological contact filtration treatment water storage tank, And a communication valve for communicating the biological contact filtration tank and the biological contact filtration treatment water storage tank with each other.

According to a third aspect of the present invention, there is provided the water purification apparatus according to the first or second aspect, wherein the biological contact filtration treatment water in the treated water storage tank and the powder injected from the powder activated carbon injection pipe. It is a water purification treatment device having a stirrer for stirring activated carbon.

The invention described in claim 4 is the first invention.
4. The water purification apparatus according to item 2 or 3, wherein a rectifier for promoting contact between the powdered activated carbon and the pollutant is provided in the treated water storage tank.

[0013] The invention described in claim 5 is the first invention.
5. The water purification apparatus according to 2, 3, or 4, wherein the powdered activated carbon has a particle size of several μm to several tens μm.

[0014] The water purification apparatus of the present invention comprises a biological filtration layer in which a support layer provided in a biological contact filtration tank main body is filled with a particulate filter medium, and a raw water provided above the biological filtration layer is subjected to biological filtration in a downward flow. A biological contact filtration tank composed of a raw water supply pipe for supplying the bed, an air blowing pipe for performing aeration for washing the biological filtration layer provided inside the support layer, and temporarily treating the biological contact filtration treatment water. A biological contact filtration treatment water storage tank to be stored in, a powdered activated carbon injection pipe provided at an arbitrary position on the bottom of the biological contact filtration tank, a communication valve for communicating the biological contact filtration tank with the biological contact filtration treatment water storage tank, A treated water outflow pipe for discharging treated water from the biological contact filtration treated water storage tank, a washing drain valve for discharging washing wastewater generated during washing of the biological filtration layer from the biological contact filtering tank, and a water level in the biological contact filtering tank during washing. For lowering An intermediate drainage valve to be used, and a water purification treatment device comprising: a biological contact filtration tank and a biological contact filtration treatment water storage tank which are integrally formed and connected with a communication valve, and a biological contact filtration treatment water storage tank A powdered activated carbon injection tube is provided at an arbitrary position at the bottom of the biological contact filtration tank, and a biological filtration layer provided in the biological contact filtration tank is aerated from an air blowing tube provided at a lower portion thereof and treated with biologically contacted filtered water containing powdered activated carbon. It is characterized by being made to wash. INDUSTRIAL APPLICABILITY The water purification treatment device of the present invention has excellent treatment performance for removing pollutants such as off-flavors (mold odor) and trihalomethane precursors in tap water, and can effectively utilize activated carbon, and has biological contact filtration. Since the treated water storage tank can be used as a powdered activated carbon treatment tank, the number of tower tanks is small and the water purification apparatus is excellent in economic efficiency.

[0015] Although not necessarily required, a stirrer for stirring the biologically contacted filtered water and the powdered activated carbon in the biologically contacted filtered water storage tank is installed, so that the pollution contained in the biologically contacted filtered water is provided. This is a water purification device that can more efficiently adsorb substances and activated carbon.

Although not always required, the storage of the powdered activated carbon in the biological contact filtration treatment water storage tank is sufficient so that the powdered activated carbon is positively brought into contact with the pollutant. By installing a weir or a flow straightening plate in the tank, it is a water purification treatment device capable of more efficiently adsorbing pollutants and activated carbon of biological contact filtration treatment water. Furthermore, by providing both a stirrer and a weir or a rectifier plate in the biological contact filtration treatment water storage tank, the water purification treatment apparatus can more efficiently absorb pollutants by activated carbon. In addition, by using powdered activated carbon having a particle size of several μm to several tens of μm, the biological filtration layer can be washed in a state where the powdered activated carbon is mixed in the biological contact filtration treatment water at the time of backwashing, and regeneration of the powdered activated carbon can be performed. It is a possible water purification treatment device.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a diagram showing an embodiment of the water purification apparatus of the present invention. In the figure, a biological filtration layer 12 filled with a ceramic porous filter medium having an average particle diameter of 4 mm as a granular filter medium with a layer thickness of about 1.5 m is filled on a support layer 13 in a rectangular biological contact filtration tank 10. And the support layer 13
Is provided with an air blowing pipe 15 for performing aeration when the biological filtration layer 12 is washed. A raw water supply pipe 14 for supplying raw water into the biological contact filtration tank 10 in a downward flow is provided on the upper part of the biological contact filtration tank 10. 1
A washing drain valve 19 for discharging water from 0 and an intermediate drain valve 20 used for an operation for lowering the water level in the biological contact filtration tank 10 at the time of washing are provided.

The biological contact filtration treatment water storage tank 16 is a storage tank for temporarily storing the biological contact filtration treatment water treated in the biological contact filtration tank 10, and the biological contact filtration treatment water storage tank 1
6, a treated water outflow pipe 18 for allowing treated water to flow out,
A powdered activated carbon injection pipe 21 provided at an arbitrary position on the bottom of the biological contact filtration treatment water storage tank 16 and a stirrer 22 for stirring the inside of the biological contact filtration treatment water storage tank 16 are provided. A communication valve 17 for communicating with the biological contact filtration treatment water storage tank 16 is provided at the bottom of the biological contact filtration tank 10 and the biological contact filtration treatment water storage tank 16. From the treated water discharged from the treated water outflow pipe 18, powdered activated carbon is removed by a solid-liquid separation process such as the coagulation sedimentation tank 2 and the sand filtration tank 3.

The biological contact filtration tank 10 and the biological contact filtration treatment water storage tank 16 are formed adjacent to each other, and are connected to each other by a communication valve 17 provided at the bottom. It may be divided by a partition plate, and the partition plate may be provided with a communication valve 17 so as to communicate with each other. Furthermore, the existing biological contact filtration tank and the biological contact filtration treatment water storage tank may be modified to form the water purification treatment device of the embodiment.

The composition of the particulate filter material used for the biological filtration layer 12 may be any filter material such as ceramics, plastics, sand, and anthracite.
The filter medium may have any shape such as a columnar shape, a cylindrical shape, a spherical shape, and a porous shape. Of course, the composition, shape, etc. of the particulate filter medium are not limited to these embodiments, and all the known particulate filter mediums as well as the granular filter medium having a good biofiltration performance to be developed in the future can be used. Is also good. In addition, the structure of the biological filtration layer 12, the thickness of the filtration layer, and the like may be a single-layer, multi-layer, or any other filtration layer, and a filtration layer of any thickness may be used.

The type of powdered activated carbon is coal-based (bituminous coal, peat, lignite, etc.), palm shell-based, dry coal, or the like.
Any type of wet charcoal may be used, and the powdered activated carbon having a particle size of about several μm to several tens μm is used. Of course, it is not limited to the following examples.

Next, the water purification process of this embodiment will be described with reference to FIG. First, during normal operation, tap water is continuously flowed downward from the raw water supply pipe 14 into the biological contact filtration tank 10. Raw tap water is biological filtration layer 12
The pollutants (for example, ammonia nitrogen, off-flavor, algae, etc.) contained in tap water are removed by the biological purification function of the biofilm attached to the surface of the granular filter medium and the filtration function of the filter layer. The biologically contacted filtered water treated in the biologically contacted filtration tank 10 flows into the biologically contacted filtered water storage tank 16 via a communication valve 17 that communicates between the biologically contacted filtration tank 12 and the biologically contacted filtered water storage tank 16. And the biological filtration layer 12
Is stored as washing water for washing. Powdered activated carbon is injected from a powdered activated carbon injection pipe 21 provided at the bottom of the biological contact filtration treatment water storage tank 16 in accordance with the concentration of the substance to be removed contained in the treatment water. Is temporarily stored. During the temporary storage, the treated water and the water-powder activated carbon are stirred and mixed by the stirrer 22, and the biological contact filtration treated water is a substance to be removed remaining in the treated water while remaining in the storage tank. It is adsorbed by activated carbon powder. Then, the powdered activated carbon to which the substance to be removed has been adsorbed is removed from the treated water by a solid-liquid separation process such as a coagulation sedimentation tank 2 and a sand filtration tank 3 at the subsequent stage. Through such a treatment step, a part of the substance to be removed contained in the water to be treated is subjected to biological treatment to render it harmless or low-molecular, and changes to a form easily adsorbed by powdered activated carbon. The water quality of the water purification apparatus is superior to the water quality obtained by the conventional powdered activated carbon adsorption treatment without biological treatment.

Next, the washing of the biological filtration layer 12 will be described with reference to FIG. Biological contact filtration treatment water storage tank 16
The biological contact filtration treatment water stored in the tank stops supply of the raw water from the raw water supply pipe 14, discharges the raw water in the biological contact filtration tank 10 from the intermediate drain valve 20, and the water level in the biological contact filtration tank 10 Lower. After that, the injection of the powdered activated carbon from the powdered activated carbon injection pipe 16 is stopped, and the communication valve 17 is opened, whereby the biological contact filtration treatment water in the storage tank 16 flows into the biological contact filtration tank 10. At this time, the air is sent to the air blowing pipe 15 and aerated, whereby the biological filtration layer 1 is formed.
The second particulate filter medium is washed. This washing water is a washing drain valve 1
It is discharged through 9.

A part of the powdered activated carbon contained in the backwash water flows into and accumulates in the biological filtration layer 12, so that the residence time of the powdered activated carbon in the treatment device is prolonged and the accumulated powdered activated carbon is also increased. At least a part of the layer is capable of exhibiting an adsorption function for a long period of time by receiving a biological regeneration action in the biological filtration layer 12. Therefore, in the water purification treatment device of the present embodiment, a system using biological treatment having no filtration function unlike a biological contact filtration treatment device such as a honeycomb contact treatment device or a rotating disk treatment device as a pretreatment of tap water is used. In comparison, activated carbon can be used more effectively, which is economical.

Further, in this embodiment, the powdered activated carbon adsorption treatment is carried out by injecting the powdered activated carbon into the biological contact filtration treatment water storage tank 16 and using the biological contact filtration treatment water. In addition, back washing of the biological contact filtration device 10 is performed with biological contact filtration water mixed with powdered activated carbon. Therefore, it is not necessary to newly provide a powdered activated carbon contact tank at the subsequent stage of the biological contact filtration treatment apparatus having the existing biological contact filtration treatment water storage tank. Compared with a conventional water purification treatment apparatus that simply combines a biological contact filtration treatment and a powdered activated carbon adsorption treatment, the apparatus is more compact, the facility cost is lower, and it is more economical.

The biological filtration layer 12 is washed with biological contact filtration water containing powdered activated carbon. However, since the particle size of the powdered activated carbon particles is as small as several μm to several tens μm, the biological filtration layer 12 is When backwashing, there is no fear that powdered activated carbon is excessively accumulated in the biological filtration layer 12 and cannot be backwashed.

As in the prior art, as a pretreatment of raw water, a water purification treatment apparatus for performing biological treatment after performing a powdered activated carbon adsorption treatment or a water purification treatment apparatus for performing biological treatment other than the biological contact filtration method as in this embodiment. In addition, since water purification treatment cannot be performed using both the powdered activated carbon contact tank and the biological contact filtration treatment water storage tank, the number of tower tanks cannot be reduced. Further, in the conventional powdered activated carbon adsorption treatment equipment, since the pollutant load on the injected powdered activated carbon is high, the consumption amount of the powdered activated carbon becomes large, so that it is possible to exhibit the economical efficiency as in the apparatus of the present invention. Can not.

That is, the water purification treatment apparatus of the present invention comprises a biological contact filtration treatment apparatus of a self-water washing type, and a powder activated carbon injection pipe for injecting fine powdered activated carbon into a biological contact filtration treatment water storage tank. This is a water purification treatment device comprising a biological contact filtration treatment water storage tank used as an activated carbon contact tank. In addition, it is clear that the biological filtration layer can be washed without impairing the biological filtration function by constantly feeding a predetermined amount of air into the air blowing pipe provided in the biological contact filtration treatment apparatus to aerate the biological filtration layer.

Next, the results of the present invention and the conventional water purification apparatus will be described with reference to Table 1. Since the conventional water purification apparatus does not perform biological treatment as pretreatment of raw water, it is a water purification treatment in which powder activated carbon adsorption treatment is performed, and an example of the treatment result is shown. As is clear from Table 1, it is shown that the purified water treatment apparatus of the present invention can provide higher quality treated water than the conventional one.

As shown in Table 1, in raw water, soluble KM
The nO ₄ consumption is 5.4 [mg / L], and the soluble trihalomethane generating ability is 26 [μg / L]. On the other hand, according to the apparatus of the present invention, the consumption of soluble KMnO ₄ is 1.7 [mg / L], and the ability to produce soluble trihalomethane is 10 [μg / L]. In particular, the solubility of trihalomethane in the conventional apparatus was 16 [μg / L], indicating that the apparatus of the present invention was extremely effective.

[0031]

[Table 1] (Conditions for powdered activated carbon adsorption treatment) Powdered activated carbon injection rate: 20 mg / L, contact time: 40 minutes,

Next, another embodiment of the water purification apparatus according to the present invention will be described with reference to FIG. In the figure,
In addition to the apparatus of the embodiment shown in FIG. 1, the powdered activated carbon injected into the biological contact filtration treatment water storage tank 16 is retained in the storage tank 16 or the contact between the powdered activated carbon and the pollutant is promoted. A weir and a flow straightening plate 23 having an action are provided in the biological contact filtration treatment water storage tank 16. Since the other configuration is the same, the description of the configuration is omitted. Although not necessarily required, adsorption of pollutants is further promoted by providing a stirrer 22 that stirs the biological contact filtration treatment water and the powdered activated carbon.

Further, by installing a weir or a flow straightening plate in the biological contact filtration treatment water storage tank 16, the activated carbon powder injected as necessary is retained in the biological contact filtration treatment water storage tank 16. It also has the function of discharging the activated carbon powder that has sufficiently adsorbed the pollutants to the coagulation sedimentation tank when discharging the treated water. With such a configuration, the adsorption treatment of the polluted substance by the powdered activated carbon can be surely performed, and the injected powdered activated carbon can be used effectively, so that the cost of purified water of the water purification treatment device is reduced.

[0034]

As described above, the present invention is a water purification treatment apparatus in which a powdered activated carbon adsorption treatment for removing pollutants is performed after a biological contact filtration treatment is performed as a pretreatment. There is an advantage that the load on pollutants is lower than that of a conventional water purification treatment apparatus using a powdered activated carbon adsorption treatment that does not perform pretreatment, and there is an advantage that tap water raw water can be treated with a relatively small amount of powdered activated carbon, and good treated water can be obtained. At the same time, since the injected powdered activated carbon can be used effectively, there is an advantage that water treatment can be performed at low cost and a water purification apparatus excellent in economy can be provided.

The water purification treatment apparatus of the present invention is an apparatus which can be easily constituted by an existing biological contact filtration tank and its storage tank, and a powdered activated carbon injection pipe for injecting powdered activated carbon into the bottom of the storage tank is optional. There is an advantage that it can be easily configured by disposing it at a position and providing a communication valve at the bottom of the biological contact filtration tank and the storage tank.

Further, according to the present invention, as compared with a conventional water purification treatment apparatus in which a biological contact filtration treatment facility and a powdered activated carbon adsorption treatment facility are simply installed in series, the apparatus is more compact, and the tower tanks and the like are more compact. Therefore, there is an advantage that the cost can be reduced, the facility cost can be reduced, and a water purification apparatus excellent in economy can be provided.

Further, according to the present invention, when washing the biological filtration layer provided in the biological contact filtration tank, fine powdered activated carbon is passed through the biological filtration layer to wash the biological filtration layer and to remove the powdered activated carbon. Since regeneration can be achieved at the same time, there is an advantage that expensive powdered activated carbon can be effectively used and the cost of water purification can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a water purification apparatus according to the present invention.

FIG. 2 is a diagram showing another embodiment of the water purification apparatus according to the present invention.

FIG. 3 is a diagram showing an outline of a conventional water purification treatment device.

FIG. 4 is a diagram showing an outline of a conventional water purification treatment device provided with an activated carbon treatment device as a pretreatment.

[Explanation of symbols]

 2 Coagulation sedimentation tank 3 Sand filtration tank 10 Biological contact filtration tank 12 Biological filtration layer 13 Support layer 14 Raw water supply pipe 15 Air blowing pipe 16 Biological contact filtration treatment water storage tank 17 Communication valve 18 Treated water outflow pipe 19 Washing drain valve 20 Intermediate Drain valve 21 Powder activated carbon injection pipe 22 Stirrer 23 Rectifier plate

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kenichiro Mizuno 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (5)

[Claims] 1. A water purification treatment apparatus for performing biological filtration, comprising: a biological contact filtration tank having a biological filtration layer and an air blowing tube for aerating the biological filtration layer; and a powder activated carbon injection for injecting powdered activated carbon into biological contact filtration treatment water. A biological contact filtration treatment water storage tank provided with a pipe, and a biological contact filtration treatment water into which the biological activated filtration powder is injected into the biological contact filtration treatment water storage tank while aerating the biological filtration layer. And a back washing means for washing the biological filtration layer by flowing into the water purification apparatus. 2. A water purification treatment device for performing biological filtration, comprising a biological contact filtration tank and a biological contact filtration treatment water storage tank for storing biological contact filtration treatment water, wherein the biological contact filtration tank is provided with biological contact filtration. A biological filtration layer filled on a support layer provided in a tank, an air blowing pipe provided on the support layer and performing aeration at the time of washing the biological filtration layer, a cleaning drain valve for discharging cleaning water, An intermediate drain valve for lowering the water level in the biological contact filtration tank during washing, a powdered activated carbon injection pipe disposed at the bottom of the biological contact filtration treatment water storage tank, the biological contact filtration tank and the biological A water purification treatment device comprising: a communication valve that communicates with a contact filtration treatment water storage tank. 3. The water treatment apparatus according to claim 1, further comprising a stirrer for stirring the biological contact filtration treatment water in the treatment water storage tank and the powdered activated carbon injected from the powdered activated carbon injection pipe. A water purification treatment device characterized by the above-mentioned. 4. The water purification treatment device according to claim 1, wherein a rectification device that promotes contact between the powdered activated carbon and the pollutant is provided in the treated water storage tank. apparatus. 5. The water treatment apparatus according to claim 1, wherein the powdered activated carbon has a particle size of several μm to several tens μm.