JP7089859B2 - Water treatment equipment and water treatment method - Google Patents

Description

The present invention relates to a water treatment apparatus and a water treatment method for treating breeding water from an aquarium for breeding aquatic organisms.

The breeding water in the aquarium in which aquatic organisms are bred may be used by circulating the breeding water from the viewpoint of reducing running costs and the like. Conventionally, when the breeding water is recycled, sand filtration is installed in the circulation route of the breeding water, and the breeding water is filtered by sand filtration to remove suspended solids and the like in the breeding water. ..

For example, Patent Document 1 describes a method of circulating and purifying breeding water through a filtration step, in which the filtration step includes a biological attachment carrier layer in which a biological attachment carrier other than sand is filled in the upper part and a sand layer in which sand is filled in the lower part. Disclosed is a method of passing breeding water in a downward flow through a multi-layer filtration layer having the above.

JP-A-2015-23841

By the way, in order to efficiently remove suspended solids and the like in breeding water, membrane filtration treatment using a filtration membrane is preferable to sand filtration. However, in the case of membrane filtration treatment, the power consumption of the pump for passing the breeding water through the filtration membrane may affect the power consumption required for operating the device, which may lead to an increase in running cost.

Therefore, an object of the present invention is to provide a water treatment device and a water treatment method capable of efficiently removing suspended solids in breeding water by sand filtration while suppressing the power consumption required for the operation of the device. Is.

The present invention has a membrane filtration means for filtering the breeding water from a water tank for breeding aquatic organisms using an extraneous filtration membrane or a precision filtration membrane, and at least a part of the treated water filtered by the membrane filtration means is described above. A water treatment device that returns to the water tank, a storage tank that stores the breeding water from the water tank, a water level gauge installed in the storage tank, and a circulation pump that sends the breeding water in the water tank to the storage tank. , And a control unit that controls the operation / stop of the circulation pump based on the water level in the storage tank measured by the water level gauge, and the membrane filtration means is installed at a position higher than the water tank. The storage tank is a water treatment device that is installed at a position higher than the membrane filtration means and allows the breeding water from the storage tank to pass through the membrane filtration means by gravity.

Further, the water treatment apparatus has a storage tank for storing the breeding water from the water tank, the membrane filtration means is installed at a position higher than the water tank, and the storage tank is higher than the membrane filtration means. It is preferable that the breeding water installed at the position is passed through the membrane filtration means by gravity.

Further, the water treatment apparatus has a backwashing means for backwashing the membrane filtration means, and when the water level of the breeding water in the storage tank reaches a predetermined water level or higher, the backwashing means causes the membrane. It is preferable to backwash the filtration means.

Further, in the water treatment apparatus, the number of times of circulation of the breeding water in the aquarium per day is preferably 6 times / day or more.

Further, the present invention has a membrane filtration step of filtering breeding water from a water tank for breeding aquatic organisms by a membrane filtration means having an ultrafiltration membrane or a precision filtration membrane, and the treated water filtered by the membrane filtration step. It is a water treatment method in which at least a part of the above is returned to the water tank, and in the membrane filtration step, the breeding water is passed through the membrane filtration means by gravity.

Further, in the water treatment method, the membrane filtration means is installed at a position higher than the water tank, and the storage tank for storing the breeding water from the water tank is installed at a position higher than the membrane filtration means. Then, it is preferable to pass the breeding water from the storage tank through the membrane filtration means by gravity.

Further, in the water treatment method, it is preferable to have a backwashing step of backwashing the membrane filtration means when the water level of the breeding water in the storage tank reaches a predetermined water level or higher.

Further, in the above water treatment method, it is preferable that the number of circulations of the breeding water in the aquarium per day is 6 times / day or more.

According to the present invention, it is possible to efficiently remove suspended solids in breeding water by sand filtration while suppressing the power consumption required for operating the apparatus.

It is a schematic block diagram which shows an example of the water treatment apparatus which concerns on this embodiment.

Embodiments of the present invention will be described below. The present embodiment is an example of carrying out the present invention, and the present invention is not limited to the present embodiment.

FIG. 1 is a schematic configuration diagram showing an example of a water treatment apparatus according to the present embodiment. The water treatment device 1 shown in FIG. 1 includes a storage tank 10, a membrane filtration device 12 having an ultrafiltration membrane or a microfiltration membrane as a membrane filtration means, a treatment water tank 14, a circulation pump 16, and pipes 18a, 18b, 18c, 18d. , The backwash pump 20, the backwash pipes 22a and 22b, and the control unit 24 are provided. A water level gauge 26 is installed in the storage tank 10 shown in FIG.

In the water treatment device 1 shown in FIG. 1, the treatment water tank 14 and the membrane filtration device 12 are installed at a position higher than the water tank 28 in which aquatic organisms are bred, and the storage tank 10 is installed at a position higher than the membrane filtration device 12. .. That is, a head difference occurs between the membrane filtration device 12 and the storage tank 10 due to the difference in position between the membrane filtration device 12 and the storage tank 10. In the water treatment device 1 shown in FIG. 1, there is a head difference between the treated water tank 14 (film filtration device 12) and the water tank 28 due to the difference in position between the treated water tank 14 (film filtration device 12) and the water tank 28. Has occurred.

In the water treatment device 1 of FIG. 1, the outlet of the water tank 28 and the inlet of the storage tank 10 are connected by a pipe 18a via a circulation pump 16. Further, the outlet of the storage tank 10 and the primary side of the membrane filtration device 12 are connected by a pipe 18b, and the secondary side of the membrane filtration device 12 and the inlet of the treatment water tank 14 are connected by a pipe 18c. Further, the outlet of the treatment water tank 14 and the inlet of the water tank 28 are connected by a pipe 18d. Further, the backwash outlet of the treatment water tank 14 and the secondary side of the membrane filtration device 12 are connected by the backwash pipe 22a via the backwash pump 20, and the backwash pipe 22b is connected to the primary side of the membrane filtration device 12. It is connected.

The control unit 24 is electrically connected to the water level gauge 26 and each pump. The control unit 24 has a function of controlling the operation / stop of each pump based on the water level measured by the water level meter 26 of the storage tank 10.

The operation of the water treatment apparatus 1 according to the present embodiment will be described.

In the aquarium 28, aquatic organisms such as fish are bred in the breeding water. Examples of the breeding water include an exhibition tank installed in an aquarium, aquaculture tank, aquarium water such as a live fish tank, and the like, and may be fresh water or seawater. Breeding water usually contains suspended solids and the like with the breeding of aquatic organisms.

The breeding water in the water tank 28 is stored in the storage tank 10 through the pipe 18a by the circulation pump 16. The breeding water in the storage tank 10 passes through the pipe 18b and is passed through the membrane filtration device 12 by gravity (water head difference), and suspended substances and the like in the breeding water are filtered by an ultrafiltration membrane or a microfiltration membrane. (Membrane filtration process). The treated water from which suspended solids and the like have been filtered is stored in the treated water tank 14 through the pipe 18c. Further, at least a part of the treated water in the treated water tank 14 is returned to the water tank 28 through the pipe 18d and recycled as breeding water in the water tank 28. In the water treatment device 1 shown in FIG. 1, the treated water is also supplied from the membrane filtration device 12 to the treated water tank 14 and from the treated water tank 14 to the water tank 28 due to the head difference.

As described above, in the water treatment device 1 shown in FIG. 1, the breeding water from the water tank 28 is filtered by the membrane filtration device 12 having an ultrafiltration membrane or a microfiltration membrane. Compared with filtration by sand filtration, it is possible to efficiently remove suspended substances and the like in breeding water.

Further, as in the water treatment device 1 shown in FIG. 1, the breeding water is passed through the membrane filtering device 12 by gravity (head difference), so that the breeding water is passed through the membrane filtering device 12 by gravity (difference). As illustrated below, the power consumption of the circulation pump 16 is reduced as compared with the case where the water head difference is not used.

When the breeding water from the water tank 28 is passed through a membrane filtration device having an ultrafiltration membrane or a microfiltration membrane without using gravity (water head difference), the breeding water uses the ultrafiltration membrane or the microfiltration membrane. The pump power required to pass through is required. For example, when the number of circulations is 6 times / day for a 10 m ³ water tank, the power consumption of the circulation pump when gravity is not used is as follows.

<When not using gravity>
The pressure loss of ultrafiltration is 0.2 MPa (considering when blocked), the circulation flow rate is 2.5 m ³ / h (= 6 times / day), the pressure loss due to piping is 0.1 MPa, and the flow rate is 2. Assuming 5 m ³ / h and a lift of 30 m (corresponding to 0.3 MPa), the power consumption of the circulation pump (for example, CRN1-8 manufactured by Grundfoss) is 0.75 kW. Further, assuming that the operating time of the circulation pump is 24 (h / day) and 365 (day / year), 0.75 (kW) x 24 (h / day) x 365 (day / year) = 6.6 MWh / year. Will be.

On the other hand, when the breeding water from the water tank 28 is passed through the membrane filtration device 12 having an ultrafiltration membrane or a microfiltration membrane by gravity (head difference) as in the present embodiment, the power of the circulation pump 16 is Pump power is sufficient to pull up the breeding water until a given head difference occurs. For example, as described above, when the number of circulations is 6 times / day for a 10 m ³ water tank, the power consumption of the circulation pump when gravity is used is as follows.

<When using gravity>
The circulation flow rate is 2.5 m ³ / h (= 6 times / day), the pressure loss due to piping is 0.1 MPa, the pressure loss of ultrafiltration is applied by the head difference, and the flow rate is 2.5 m ³ as the required pump capacity. Assuming / h and a lift of 10 m (corresponding to 0.1 MPa), the power consumption of the circulation pump (for example, CRN1-8 manufactured by Grundfoss) is 0.55 kW. Further, assuming that the operating time of the circulation pump is 24 (h / day) and 365 (day / year), 0.55 (kW) x 24 (h / day) x 365 (day / year) = 4.8 MWh / year. Will be.

In this way, the power consumption of the circulation pump is reduced by passing the breeding water through the membrane filtration device 12 by gravity (head difference). As a result, the power consumption required for operating the device can be suppressed, and eventually the increase in running cost can be suppressed. The water head difference (difference in position between the storage tank 10 and the membrane filtration device 12 in FIG. 1) when the breeding water is passed through the membrane filtration device 12 is the ultrafiltration membrane used in the membrane filtration device 12. Although it depends on the performance of the microfiltration membrane and the like, in consideration of the pressure loss of the membrane, for example, it is preferably in the range of 1 m to 30 m, and preferably in the range of 5 m to 20 m.

Further, in the water treatment device 1 shown in FIG. 1, since the treated water from the membrane filtration device 12 is returned to the water tank 28 by gravity (head difference), the power consumption of the circulation pump 16 required for circulation of the breeding water is consumed. Will be further reduced.

By the way, in the water treatment apparatus 1 shown in FIG. 1, when the membrane filtration step is continued, suspended substances and the like in the breeding water are deposited on the membrane surface of the ultrafiltration membrane and the microfiltration membrane, and the pores of the filtration membrane are closed. It is preferable to carry out a backwashing step as it may cause fouling. For example, after stopping the circulation pump 16, the backwash pump 20 is operated to use at least a part of the treated water in the treated water tank 14 as backwash water, and the backwash pipe 22a is passed through the secondary side of the membrane filtration device 12. The filtration membrane is washed by passing the liquid through the primary side (backwashing step). Then, the backwash drainage on the primary side of the membrane filtration device 12 is discharged from the backwash pipe 22b.

Normally, when a suspended substance or the like is deposited on the membrane surface of an ultrafiltration membrane or a microfiltration membrane, the amount of breeding water passing through the filtration membrane decreases, so that the water level of the breeding water in the storage tank 10 rises. Therefore, it is desirable to carry out the backwashing step when the water level of the breeding water in the storage tank 10 reaches a predetermined water level or higher. In the water treatment apparatus 1 shown in FIG. 1, for example, the water level data measured by the water level gauge 26 installed in the storage tank 10 is transmitted to the control unit 24, and is preset with the transmitted water level data by the control unit 24. The predetermined value is compared. Then, when the water level data is equal to or higher than a predetermined value, the control unit 24 controls the operation / stop of each pump, and the backwashing step described above is carried out. The predetermined value may be set as appropriate.

Further, the backwashing step may be performed at predetermined time intervals. That is, the cycle of performing the membrane filtration step for a predetermined time and then performing the backwashing step for a predetermined time may be repeated. Further, when the water level of the breeding water in the storage tank 10 reaches a predetermined water level or higher during the membrane filtration step of this cycle, it is preferable to carry out the backwashing step.

The number of times of circulation of the breeding water in the aquarium 28 per day is preferably 6 times / day or more, and more preferably 6 times / day to 24 times / day. The number of times the breeding water in the water tank 28 is circulated is the number of times that the breeding water in the water tank 28 passes through the circulation route (pipes 18a to 18d) per day, and is expressed by the following formula.
Number of circulations (times / day) = 24h / day x circulation flow rate (m ³ / h) ÷ water tank volume (m ³ )

By setting the number of circulations of the breeding water in the aquarium 28 per day to 6 times / day or more, it is possible to efficiently remove suspended solids and the like in the breeding water, and the breeding water in the aquarium 28 is clarified. It becomes easy to maintain the state. Generally, a sand filtration device is used to remove suspended substances, and in order to maintain a clear state, the number of circulations must be 24 or more, but in the present application, the filtration accuracy is higher than that of the sand filtration device. Since it is a membrane filtration device with a high value, it is possible to maintain a clear state with a smaller number of circulations than a conventional sand filtration device. Further, in the water treatment device 1 shown in FIG. 1 in which the breeding water is passed through the membrane filtration device 12 by gravity (head difference), the number of circulations of the breeding water in the water tank 28 per day is set to 6 times / day or more. However, the power consumption of the circulation pump 16 can be suppressed.

In the water treatment device 1 shown in FIG. 1, the membrane filtration device 12 is installed at a position higher than the water tank 28, and the storage tank 10 is installed at a position higher than the membrane filtration device 12. It is not limited to the above as long as it is an installation form in which the liquid of breeding water can be passed by gravity (water head difference). Although the description in the figure is omitted, for example, the storage tank 10 is installed at a position lower than the water tank 28 in which aquatic organisms are bred, and the membrane filtration device 12 and the treatment water tank 14 are installed at a position lower than the storage tank 10. It may be in the form. Even with such a configuration, a water head difference occurs between the membrane filtration device 12 and the storage tank 10 due to the difference in the positions of the membrane filtration device 12 and the storage tank 10, so that the breeding water in the storage tank 10 is used. Due to gravity (water head difference), the liquid is passed through the membrane filtration device 12, and suspended substances and the like in the breeding water are filtered by an ultrafiltration membrane or a microfiltration membrane (membrane filtration step). Since the treated water from which the suspended solids and the like have been removed is located at a position lower than the water tank 28, it is necessary to return it to the water tank 28 by the circulation pump 16.

As for the installation form of the storage tank 10 and the membrane filtration device 12, the installation form in which the membrane filtration device 12 is installed at a position higher than the water tank 28 and the storage tank 10 is installed at a position higher than the membrane filtration device 12 is the storage tank. It is preferable to install the membrane filtration device 12 at a position lower than the water tank 28 and the membrane filtration device 12 at a position lower than the storage tank 10 in terms of reducing the overload on the building frame. In recent years, aquariums and the like may be operated as tenants such as commercial facilities, and water treatment facilities may be distributed to higher floors. In the installation mode in which the storage tank 10 is installed at a position lower than the water tank 28 and the membrane filtration device 12 is installed at a position lower than the storage tank 10, the water tank 28 having a large volume such as a breeding water tank is replaced with a storage tank 10 or a membrane having a small capacity. It may have to be installed on a higher floor than the filtration device 12. In this case, it is necessary to strengthen the design strength in consideration of the excessive load on the building frame, and there is a possibility that the cost to the building frame will increase.

In the water treatment device 1 of the present embodiment, the storage tank 10 is not an indispensable configuration, but the timing of carrying out the backwashing step for the membrane filtration device 12 is determined from the water level of the breeding water in the storage tank 10 and the like. It is desirable to install a storage tank 10. Even if there is no storage tank 10, if the breeding water is pulled up to a position where a head difference is formed by the pipe 18a, the breeding water can be passed through the membrane filtration device 12 by gravity (head difference). ..

Although the treated water tank 14 is not an essential configuration in the water treatment device 1 of the present embodiment, it is desirable to install the treated water tank 14 in terms of carrying out a backwashing step for the membrane filtration device 12.

The membrane filtration device 12 may be any as long as it has an ultrafiltration membrane (UF membrane) or a microfiltration membrane (MF membrane), and is not particularly limited.

In the water treatment device 1 according to the present embodiment, an ozone treatment device or an activated carbon treatment device including an ozone generator may be installed in the circulation path (pipes 18a to 18d). The breeding water in the water tank 28 may contain organic substances, ammonia nitrogen, etc. in addition to suspended solids due to the breeding of aquatic organisms. Since organic matter, ammonium nitrogen, and the like can be efficiently treated, clearer breeding water can be returned to the water tank 28.

The water treatment device 1 of the present embodiment is used in an aquarium, a farm, or the like for treating the breeding water used for breeding aquatic organisms, and is particularly used in an inland aquarium. Suitable. Since inland aquariums are often buildings consisting of multiple floors, if the storage tank 10 and the membrane filtration device 12 are distributed and arranged on each floor, the head difference for passing breeding water to the membrane filtration device 12 Can be easily formed. If the storage tank 10 and the membrane filtration device 12 cannot be distributed and arranged on each floor, for example, the storage tank 10 is placed on a pedestal or the like having a predetermined height and placed on the membrane filtration device 12. It suffices to secure a head difference for passing the breeding water.

1 water treatment device, 10 storage tank, 12 membrane filtration device, 14 treatment water tank, 16 circulation pump, 18a-18d piping, 20 backwash pump, 22a, 22b backwash piping, 24 control unit, 26 water level gauge, 28 water tank.

Claims (7)

It has a membrane filtration means that filters the breeding water from the aquatic tank that breeds aquatic organisms using an ultrafiltration membrane or a microfiltration membrane, and returns at least a part of the treated water filtered by the membrane filtration means to the tank. It is a water treatment device
A storage tank for storing the breeding water from the water tank, a water level gauge installed in the storage tank, a circulation pump for sending the breeding water in the water tank to the storage tank, and the storage measured by the water level gauge. It has a control unit that controls the operation / stop of the circulation pump based on the water level in the tank.
The membrane filtration means is installed at a position higher than the water tank, the storage tank is installed at a position higher than the membrane filtration means, and the breeding water from the storage tank is passed through the membrane filtration means by gravity. A water treatment device characterized by It has a backwashing means for backwashing the membrane filtration means.
The water treatment apparatus according to claim 1 , wherein when the water level of the breeding water in the storage tank reaches a predetermined water level or higher, the membrane filtration means is backwashed by the backwashing means. The water treatment apparatus according to any one of claims 1 to 2 , wherein the number of times of circulation of the breeding water in the aquarium per day is 6 times / day or more. It has a membrane filtration step of filtering the breeding water from a water tank for breeding aquatic organisms by a membrane filtration means having an ultrafiltration membrane or a precision filtration membrane, and at least a part of the treated water filtered by the membrane filtration step is described above. It is a water treatment method that returns to the water tank.
In the membrane filtration step, a water treatment method comprising passing the breeding water through the membrane filtration means by gravity. The membrane filtration means is installed at a position higher than the aquarium, and the storage tank for storing the breeding water from the aquarium is installed at a position higher than the membrane filtration means.
The water treatment method according to claim 4, wherein in the membrane filtration step, the breeding water from the storage tank is passed through the membrane filtration means by gravity. The water treatment method according to claim 5 , further comprising a backwashing step of backwashing the membrane filtration means when the water level of the breeding water in the storage tank reaches a predetermined water level or higher. The water treatment method according to any one of claims 5 to 6 , wherein the number of times of circulation of the breeding water in the aquarium per day is 6 times / day or more.

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