JP2014240050A - Biological contact filtration apparatus - Google Patents

Abstract

A biological contact filtration device having a high filtration rate by a pressure filtration method is provided. A sealed filtration tank 11 into which raw water is supplied and treated water after filtration is discharged, a filter medium 14 capable of supporting microorganisms filled in the filtration tank 11, and a water level in the filtration tank 11 are measured. A water level meter 15, an exhaust valve 16 that exhausts the gas in the filtration tank 11, and a control unit 17 that controls the exhaust flow rate of the exhaust valve 16 so as to keep the water level at the target water level. Since the filtration tank 11 is a closed type, it can be filtered by a pressure filtration method and the filtration speed is fast. Since the water level in the filtration tank 11 is exhausted so as to keep the target water level, even if gas is discharged from the raw water, the water level does not drop or rise, and a continuous and stable operation can be performed. [Selection] Figure 1

Description

  The present invention relates to a biological contact filtration device. More specifically, the present invention relates to a biological contact filtration device that removes impurities such as iron, manganese, and ammonia nitrogen contained in raw water by the action of microorganisms such as iron bacteria, manganese bacteria, and nitrifying bacteria.

  In general, the raw water supplied to the biological contact filtration device is aerated in order to obtain a dissolved oxygen concentration suitable for the activity of microorganisms. Since a part of the air taken into the raw water is discharged as bubbles during the filtration, the conventional biological contact filtration device is constituted by a filtration pond or an open type filtration tank in which air can be freely discharged (for example, Patent Document 1). As described above, the conventional biological contact filtration device cannot use a sealed filtration tank, so it cannot adopt a pressure filtration method, and has a problem that a filtration rate is slow because filtration is mainly performed by a natural equilibrium method. .

JP 2003-290784 A

  In view of the above circumstances, an object of the present invention is to provide a biological contact filtration device having a high filtration rate by a pressure filtration method.

A biological contact filtration device according to a first aspect of the present invention is a sealed filtration tank in which raw water is supplied and treated water after filtration is discharged, a filter medium filled in the filtration tank and capable of supporting microorganisms, and in the filtration tank A water level meter for measuring the water level of the filter, an exhaust valve for exhausting the gas in the filtration tank, and a control means for controlling the exhaust flow rate of the exhaust valve so as to keep the water level measured by the water level meter at a predetermined target water level And.
In the biological contact filtration device according to the second invention, in the first invention, the target water level is a water level that does not reach the exhaust valve.

According to 1st invention, since a filtration tank is a closed type, the pressure in a filtration tank can be raised and it can filter by a pressure filtration system. Therefore, the filtration speed is fast. Moreover, since the water is exhausted so that the water level in the filtration tank is maintained at the target water level, the water level does not drop or rise even when gas is discharged from the raw water, and a continuous and stable operation can be performed.
According to the second invention, since the exhaust valve and the water surface are separated by the gas phase, it is possible to prevent the raw water from adhering to the exhaust valve and preventing the impurities in the raw water from adhering to the exhaust valve and causing malfunction.

It is the schematic of the water purification equipment by which the biological contact filtration apparatus which concerns on one Embodiment of this invention was used.

Next, an embodiment of the present invention will be described with reference to the drawings.
A biological contact filtration device 1 according to an embodiment of the present invention is used as a part of water purification equipment A as shown in FIG. In addition, the water purification equipment A is an illustration and the biological contact filtration apparatus 1 may be used for the water purification equipment of a structure different from the water purification equipment A.

First, the configuration of the water purification facility A will be described.
The water purification facility A is a water purification facility suitable for removing impurities such as iron, manganese, and ammonia nitrogen contained in well water and river water. Hereinafter, water to be treated such as well water and river water is referred to as “raw water”. The water purification equipment A includes a biological contact filtration device 1 for removing iron, ammonia nitrogen, and a part of manganese contained in raw water, and a manganese removal filtration device 2 for removing the remaining manganese. .

  The raw water pumped up by the pump 3 is aerated by self-sucking air by the ejector 4 while flowing through the supply pipe P1. The raw water whose dissolved oxygen concentration is adjusted by aeration is supplied to the biological contact filtration device 1. In the biological contact filtration device 1, iron contained in the raw water becomes a hydroxide, and a part of manganese is captured as an oxide. Ammonia nitrogen contained in the raw water is nitrified. In this way, intermediate treated water is generated by the biological contact filtration device 1. The intermediate treated water is sterilized by adding a chlorine agent such as sodium hypochlorite from the chlorinating agent injection unit 5 in the middle of flowing through the intermediate treated water pipe P2, and from the flocculant injecting unit 6 to polyaluminum chloride (PAC). A flocculant such as the above is added, and oxides, hydroxides and suspended substances that cannot be captured by the biological contact filtration device 1 are aggregated. Thereafter, the intermediate treated water is supplied to the manganese removal filter 2. The manganese removal filtration device 2 is a filter tank 21 in which a catalyst 22 coated with manganese dioxide is filled. In the manganese removal filtration device 2, manganese remaining in the intermediate treated water is oxidized by manganese dioxide and turbidity is removed to produce purified water. The manganese dioxide coated on the catalyst 22 is weakened in catalytic ability by oxidizing manganese remaining in the intermediate treated water, but is oxidized by the chlorinating agent added from the chlorinating agent injection unit 5 and based on the catalytic ability. Return. The chlorinating agent thus also has a function of activating the manganese dioxide of the catalyst 22. The purified water is guided and stored in the purified water tank 7 through the purified water pipe P3.

Next, the configuration of the biological contact filtration device 1 will be described.
The biological contact filtration device 1 includes a substantially cylindrical closed filtration tank 11. A supply port 12 is provided in the upper part of the filtration tank 11, and a discharge port 13 is provided in the lower part. A supply pipe P <b> 1 is connected to the supply port 12, and raw water is supplied to the filtration tank 11. An intermediate treated water pipe P <b> 2 is connected to the discharge port 13, and the filtered intermediate treated water is discharged from the filtration tank 11. The “intermediate treated water” corresponds to the “treated water” described in the claims. In addition, the “sealed filter tank” described in the claims means that the filter tank is configured to be airtight and liquid-tight except for a supply port to which raw water is supplied and a discharge port to which treated water is discharged. Means that The shape of the filtration tank 11 is not particularly limited, and may be a cylindrical shape, a rectangular tube shape, or a rectangular parallelepiped shape.

  The filter tank 11 is filled with a filter medium 14 in a partial region between the supply port 12 and the discharge port 13. The filter medium 14 is not particularly limited as long as it can support microorganisms used for biological contact filtration. For example, in addition to porous filter media such as zeolite, anthracite, garnet, pumice, activated carbon, etc., filter sand is used. be able to.

  Well water and river water contain microorganisms such as iron bacteria (iron-oxidizing bacteria), nitrifying bacteria (nitrifying bacteria), and manganese bacteria (manganese-oxidizing bacteria) that originally exist in the soil. By supplying the raw water to the biological contact filtration device 1, these microorganisms contained in the raw water adhere to the filter medium 14 and proliferate to exert a filtration function. By utilizing the biological treatment of the microorganisms supported on the filter medium 14, impurities such as iron, manganese, and ammonia nitrogen contained in the raw water are removed to generate intermediate treated water. Specifically, iron contained in the raw water becomes a hydroxide by the action of iron bacteria and is captured by the filter medium 14. Part of the manganese becomes an oxide by the action of manganese bacteria and is captured by the filter medium 14. Ammonia nitrogen is nitrified by the action of nitrifying bacteria.

  In addition, since it may take time for the microorganisms to grow, in order to shorten the period, the filter medium 11 previously loaded with the microorganisms may be filled in the filtration tank 11. Furthermore, since the biological contact filtration device 1 of the present embodiment is intended for treatment of well water and river water containing iron, manganese, and ammoniacal nitrogen, iron bacteria, manganese bacteria, Nitrifying bacteria are preferably used. However, the filter medium 14 may carry various microorganisms used for biological contact filtration in addition to the microorganisms. Moreover, the type may be one type or a plurality of types.

  The raw water supplied to the biological contact filtration device 1 is aerated in order to obtain a dissolved oxygen concentration suitable for the activity of the microorganisms supported on the filter medium 14. As described above, in the present embodiment, the raw water is aerated by the air sucked by the ejector 4. Note that a blower or a compressor may be connected to the ejector 4 to melt the air under pressure. In addition to the configuration in which the raw water is aerated before being supplied to the biological contact filtration device 1, a configuration in which a diffuser or the like is installed in the filtration tank 11 and the raw water is aerated in the biological contact filtration device 1 may be used. . Furthermore, instead of the configuration in which air is supplied to the raw water, a configuration in which oxygen is supplied to the raw water using an oxygen cylinder or the like may be used.

  A part of the gas (air or oxygen) taken into the raw water by aeration becomes bubbles inside the filtration tank 11 and is separated from the raw water and discharged. If the filtration tank 11 is a closed type as in this embodiment, the discharged gas accumulates in the upper part of the filtration tank 11 because there is no escape path. If the accumulated gas is not exhausted to the outside of the filtration tank 11, the pressure of the gas phase above the filtration tank 11 gradually increases, and the water level in the filtration tank 11 may be pushed down to be lower than that of the filter medium 14. If this happens, the raw water cannot be sufficiently filtered. To prevent this, the gas in the filtration tank 11 must be exhausted. The biological contact filtration device 1 of this embodiment is characterized by an exhaust mechanism that exhausts the gas in the filtration tank 11.

  An exhaust mechanism of the biological contact filtration device 1 includes a water level meter 15 that measures the water level in the filtration tank 11, an exhaust valve 16 that exhausts the gas in the filtration tank 11, and a control connected to the water level gauge 15 and the exhaust valve 16. Means 17. The water level meter 15 is not particularly limited as long as the measurement result can be input to the control means 17, and various water level meters such as a capacitance type, an ultrasonic type, a radio wave type, and a float type can be used.

  An exhaust pipe 18 is connected to the upper part of the filtration tank 11, and an exhaust valve 16 is provided in the exhaust pipe 18. By opening the exhaust valve 16, the gas in the filtration tank 11 can be exhausted through the exhaust pipe 18. The exhaust valve 16 is not particularly limited as long as the exhaust flow rate can be controlled by the control of the control means 17, and for example, an electric proportional control valve is used.

  The control means 17 is configured by a computer or an electronic circuit, and controls the exhaust flow rate of the exhaust pipe 18 based on the measurement result of the water level meter 15 as an input. Specifically, the control means 17 controls the exhaust gas flow rate by adjusting the opening of the exhaust valve 16 so as to keep the water level measured by the water level gauge 15 at a predetermined target water level. That is, feedback control is performed using the water level in the filtration tank 11 as a control amount and the exhaust flow rate of the exhaust pipe 18 as an operation amount.

  The exhaust mechanism of the biological contact filtration device 1 is configured as described above, and is exhausted so as to keep the water level in the filtration tank 11 at the target water level. Therefore, even if gas is discharged from the raw water, the gas phase pressure rises. The water level will not fall. Moreover, as the biological contact filtration device 1 continues the filtration process, oxides, hydroxides, and the like adhere to the filter medium 14 and the loss head gradually rises. However, even if the loss head increases, the water level does not increase due to the action of the exhaust mechanism. As described above, the gas phase pressure can be adjusted to an appropriate pressure while exhausting the gas in the filtration tank 11, so that the water level in the filtration tank 11 does not fall or rise and is continuously stable. Can do.

  Here, the target water level is set to a water level that does not reach the exhaust valve 16. In the configuration in which the exhaust valve 18 is provided in the exhaust pipe 18 as in this embodiment, the target water level is set to a water level that does not reach the connection between the filtration tank 11 and the exhaust pipe 18. In addition, it is preferable to set the target water level so that a gas phase having a predetermined thickness is provided between the exhaust valve 16 (connection portion between the filtration tank 11 and the exhaust pipe 18) and the surface of the raw water. The target water level is set such that the exhaust valve 16 and the water surface are separated from each other by a gas phase, and the raw water does not adhere to the exhaust valve 16 even if splashes fly due to an impact such as inflow of raw water.

  If raw water adheres to the exhaust valve 16, impurities such as oxides and hydroxides may adhere to the exhaust valve 16 and cause malfunction. However, by setting the target water level as described above, the exhaust valve 16 and the water surface are separated from each other by a gas phase, so that raw water does not adhere to the exhaust valve 16 and malfunction of the exhaust valve 16 can be prevented. Moreover, it is possible to prevent the raw water from being ejected from the exhaust pipe 18.

  Since the filtration tank 11 is a sealed type, the biological contact filtration device 1 can increase the pressure in the filtration tank 11 by pumping the raw water by the pump 3 and can be filtered by a pressure filtration method. Therefore, the filtration rate is faster than that of the natural equilibrium method. And since it exhausts so that the water level in the filtration tank 11 may be kept at a target water level, a water level does not fall or rise, but a stable operation can be performed continuously.

  Moreover, since the biological contact filtration apparatus 1 can be filtered by a pressure filtration system, the apparatus can be reduced in size as compared with a natural equilibrium system or the like, and the equipment cost can be reduced. For example, it is not necessary to set the height of the filtration tank 11 high in order to increase the water pressure in consideration of an increase in the loss head.

  Generally, like the water purification equipment A of this embodiment, the biological contact filtration device 1 is used in combination with other filtration devices such as the manganese removal filtration device 2. If the biological contact filtration device 1 is an open type, the dynamic pressure of the pump 3 that supplies the raw water cannot be applied to the treated water side. Therefore, the intermediate treated water discharged from the biological contact filtration device 1 is removed at the subsequent stage. In order to supply to the manganese filtration apparatus 2, it is necessary to provide another pump in the intermediate treated water pipe P2. However, since the biological contact filtration device 1 of the present embodiment can be filtered by the pressure filtration method, the intermediate treated water can be supplied to the manganese removal filtration device 2 and the purified water can be supplied to the water purification tank 7 only by the dynamic pressure of the pump 3. Thus, it is not necessary to install an extra pump, and the incidental equipment and the grounding place are unnecessary, so that the equipment cost can be reduced.

  In general, noise is generated in contact with gas and liquid in aeration of raw water. If the biological contact filtration device 1 is an open type, noise generated by aeration leaks to the outside as it is and noise becomes a problem. . In order to reduce the noise to the outside, it is conceivable to install the biological contact filtration device in the building, but in this case, there is a problem that the equipment cost becomes high. However, in this embodiment, aeration to the raw water is performed in the sealed space inside the supply pipe P1 or the biological contact filtration device 1, so that noise generated by aeration does not leak to the outside, and it is not necessary to install it in the building. Therefore, the equipment cost can be reduced.

  Well water was filtered using the water purification equipment A. Here, the filtration speed is 250 m / day, the continuous filtration time is 24 hours, and the target water level of the exhaust mechanism of the biological contact filtration device 1 is 1.35 m (water surface height) from the surface of the filter layer constituted by the filter medium 14. To 0.2 m in height from the top of the filtration tank 11 to the upper lid. The exhaust pipe 18 is connected to the upper lid of the upper end of the filtration tank 11.

The water purification equipment A is operated under the above conditions, the water level in the filtration tank 11 in operation, the amount of treated water of the biological contact filtration device 1, the intake amount from the ejector 4, the exhaust amount from the exhaust valve 16, the opening degree of the exhaust valve 16 The pressure in the filtration tank 11 was measured. The results are shown in Table 1.

  As shown in Table 1, it was found that the water level in the filtration tank 11 can be stably maintained at 1.35 m during continuous filtration for 24 hours. In addition, the amount of treated water, the amount of intake air, and the amount of exhaust during operation were almost constant. From this, it was found that the biological contact filtration device 1 can be operated continuously and stably.

  Moreover, it turned out that the opening degree of the exhaust valve 16 becomes small gradually with progress of filtration time, and the pressure in the filtration tank 11 becomes large gradually with progress of filtration time. This is because the loss head gradually increases as the filtration process is continued, and the water level rises when the pressure in the filtration tank 11 is constant. It is because the pressure in the filtration tank 11 is raised by decreasing and the water level is kept constant. From this, the biological contact filtration apparatus 1 adjusts the pressure of the gas phase to an appropriate pressure while exhausting the gas in the filtration tank 11, and keeps the water level in the filtration tank 11 constant and continuously stable. I found that I can drive.

A Water purification equipment 1 Biological contact filtration device 11 Filtration tank 12 Supply port 13 Discharge port 14 Filter medium 15 Water level meter 16 Exhaust valve 17 Control means 18 Exhaust pipe 2 Manganese filter 3 Pump 4 Ejector 5 Chlorine agent injection unit 6 Coagulant injection unit 7 Water purification tank

Claims (2)

A sealed filtration tank in which raw water is supplied and treated water after filtration is discharged;
A filter medium capable of supporting microorganisms, filled in the filtration tank;
A water level meter for measuring the water level in the filtration tank;
An exhaust valve for exhausting the gas in the filtration tank;
And a control means for controlling the exhaust flow rate of the exhaust valve so as to keep the water level measured by the water level meter at a predetermined target water level. The biological contact filtration device according to claim 1, wherein the target water level is a water level that does not reach the exhaust valve.