JPH03280821A - Purifier for fish culture water - Google Patents

Abstract

PURPOSE:To obtain the subject device with high reliability capable of removing pathogenic germs and molds contained in water and providing normal raising by arranging a biological treating tank and pressure driving separation membrane module in a purifying process. CONSTITUTION:Fish culture water 111 is overflowed from an overflow wall 37 of a fish culture tank 30 equipped with a gas diffusing pipe 31, connected through pipes 39 and 40 to, e.g. a biological treating vessel having a fixed bed 41 using, e.g. active carbon or sand as a filtration bed 46, then stored in, e.g. a storage tank 44, passed through a pump 56 and a pipe 93 and returned to the fish culture tank 30. The water is then passed through the storage tank 44, a pipe (62c), an ultrafiltration membrane module 64 and a pipe 80 to remove microorganisms by timer operation. The resultant water is then circulated and returned to the storage tank 44.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a fish farming water purification technique for circulating and purifying water in tanks, ponds, and rivers in which fish and shellfish are raised.

(Prior Art) FIG. 3 shows a schematic configuration of a conventional fish farming water purification device.

A diffuser pipe 2 is arranged at the lower part of the fish tank 1, and a pipe 4. Air is supplied into the fish tank 1 through the aeration pipe 2 in order. On the other hand, makeup water 5 is supplied into the fish tank 1 through a pipe 6, and fish 7 are raised therein.

Overflow water from the fish culture tank 1 is injected into a fixed bed 9 via a pipe 8,
Water that has been biologically treated and filtered in this fixed bed 9 is supplied to a settling tank 11 via a pipe 10. The liquid in the sedimentation tank 11 is returned to the fish culture tank 1 through the pipe 13 by operating the pump 12, and the fish culture water is circulated and purified through these treatments.

(Problem to be Solved by the Invention) However, in such a conventional fish farming water purification device, if pathogenic bacteria or mold gets mixed into the fish tank 1 and grows, the pathogenic bacteria or mold cannot be captured by the fixed bed 9. It floats in the sedimentation tank 11 and is further returned to the fish culture tank 1. Even if the purification operation was carried out in this state, pathogenic bacteria and mold were always present in the fish culture tank 1 and multiplied, causing problems such as the fish 7 becoming sick and dying.

If the fish tank 1 is contaminated with pathogenic bacteria or mold in this way,
Fish culture tank 1 and fixed bed 9. All the piping systems had to be sterilized and restarted, making the running costs of breeding extremely high.

Furthermore, as pathogenic bacteria and molds multiply and consume dissolved oxygen in the liquid in the fish culture tank 1, the dissolved oxygen concentration necessary for the growth of the fish 7 decreases, causing the problem that the fish 7 die.

The present invention has been made to solve the above-mentioned drawbacks, and its purpose is to provide highly reliable fish farming water purification that removes pathogenic bacteria and mold contained in the water and allows normal fish breeding. The goal is to provide equipment.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, we have conducted intensive studies and found that in a fish farming water purification device that circulates and purifies fish farming water, a biofilm treatment tank and pressure-driven separation are used in the purification process. By installing a membrane module and biologically treating fish culture water in a biofilm treatment tank, and then filtering it with a pressure-driven separation membrane, pathogenic bacteria and mold can be removed from the fish culture water, resulting in fish culture water that can be used to raise fish normally. It has been found.

(Function) In other words, by biologically treating the fish culture water in a biofilm treatment tank, substances that inhibit fish growth such as ammonia and organic matter in the fish culture water are removed, and by filtration with a pressure-driven separation membrane, pathogenic bacteria and fungi are removed. removed. For example, if this filtered water is returned to the fish tank and circulated and purified, pathogenic bacteria and
There is no mold and good water quality is maintained where fish can grow normally.

[Example] FIG. 1 shows an embodiment of the invention.

An aeration pipe 31 is disposed in the lower part of the fish culture tank 30, and the aeration pipe 31 is connected to an air source 33 via a pipe 32.

A pipe 34 is provided at the upper end of the fish tank 30, and an on-off valve 35 is provided at the bottom.
A tube 36 having a diameter is provided, respectively. Further, an overflow wall 37 is provided at the upper part of the fish culture tank 30.

An on-off valve 3 is installed on the side of the fish tank 3o where the overflow wall 37 is located.
8 is connected to the pipe 39, and this pipe 39 is connected to the upper end of a fixed bed 41, which is a biofilm treatment tank, via a pipe 40.
Further, the pipe 39 is connected to the upper end of a storage tank 44 via a pipe 43 having an on-off valve 42 .

The fixed bed 41 includes an upper gap 45, a filter bed 46, and a support material 47.
and a lower gap 48, and the filter bed 46 is filled with a material such as activated carbon, zeolite, sand, or ceramics.

A pipe 50 is connected to the overflow wall 49 on the side surface of the storage tank 44 . Further, a pipe 52 having an on-off valve 51 is connected to the bottom of the storage tank 44 .

The lower part of this storage tank 44 and the lower gap part 4 of the fixed bed 41
It is connected to the 8th side by a pipe 54 having an on-off valve 53.

Further, the side surface of the storage tank 44 is connected to a pipe 55. Pump 56, 95
7. 58. 59. 60. Hr14 valve 61
The ultrafiltration membrane module (hereinafter abbreviated as UF membrane module) 64, which is one of the pressure separation drive membranes, is passed through the valve pipes 12a, 62b, the sponge ball collector 63, and the pipe 62c in sequence.
It is connected by piping to the inlet side 65 of.

The concentrate outlet side 66 of this UF membrane module 64 is connected to the pipe 7
0. Sponge ball collector 71-2 pipe 72゜73.
Open/close valve 74. Tube 75. 76, control valve 77, pipe 78. Flow meter 79. Piping is connected to the bottom of the storage tank 44 via pipes 80 in sequence.

On the other hand, the filtered acid outlet side 81 of the UF membrane module 64 is connected to the upper end of the fish culture tank 30 via a pipe 83 and a pipe 84 having a flow meter 82 in this order.

The connecting portion between the pipe 57 and the pipe 58 is a pipe 86 having an on-off valve 85.
are connected to the bottom of the fixed bed 41 via pipes 58 and 59
The connection part is the pipe 87. Control valve 88° pipe 89. Open/close valve 90.
Tube 91. Flowmeter 92. It is connected to the upper end of the fish tank 3o via a pipe 93 and a pipe 84 in this order.

The connecting portion between the pipe 59 and the pipe 60 is a pipe 95 having an on-off valve 94.
is connected to the joint between pipe 72 and pipe 73 through pipe 62a.
The connecting portion between the pipe 62b and the pipe 62b is a pipe 96° opening/closing valve 99. tube 100
It is connected to the connecting portion of the pipe 75 and the pipe 76 through the pipe 75 and the pipe 76 in sequence.

Note that a level controller 101 is arranged above the storage tank 44 and is electrically connected to the pump 56. Further, a sponge ball 102 for cleaning the UF membrane is housed in the sponge ball collector 71.

Further, although not shown, a timer electrically connected to the on-off valve and the pump 56 is provided.

Next, the operation of this embodiment will be explained by dividing it into four steps: (1) normal operation process, (2) UF membrane operation process, (2) UF membrane cleaning process, and (2) fixed bed cleaning process.

■ Normal operation process Supplying makeup water 110 into the fish tank 30 through the pipe 34,
The fish culture water 111 is overflowed from the overflow wall 37.

Air source 33 to tube 32. Air is blown into the fish tank 30 through the aeration pipe 31 in order to bring the dissolved oxygen concentration to a saturated state (8
1g/1 or more). In this state, there is one fish in the fish tank 30.
12 and raise the fish.

In addition, by opening on-off valves 38 and 53 and closing all other on-off valves, overflow water can be removed from pipe 39 and on-off valve 38.
．． A fixed bed 41 is supplied via a pipe 40 in turn.

The overflow water injected into the upper gap 45 is biologically treated by aerobic microorganisms and nitrifying bacteria on the surface of the filter medium while passing through the filter bed 46 . Ammonia is nitrified by nitrifying bacteria, and organic matter is also biodegraded aerobically. Suspended solids with large particle sizes (hereinafter abbreviated as SS) are also retained in the bed.

The biologically treated water descends through the support member 47 and the lower gap 48, and passes through the pipe 54. It is supplied to the storage tank 44 via the on-off valve 53.

When the water in the storage tank 44 overflows through the pipe 55, the on-off valve 90 is opened and the pump 56 is activated. As a result, the liquid in the storage tank 44 is transferred to the pipe 87° regulating valve 88. Tube 89.
Open/close valve 90. Tube 91. Flowmeter 92. Tube 93. The fish are returned to the fish tank 30 through the same 84 in sequence. Note that the level controller 101 functions as an interlock for the pump 56.

Circulating purification is performed by repeating the above operations.

This operation is continued for t1 time as shown in FIG. 2, and after the t1 time has elapsed, a timer (not shown) switches to the next step, the UF membrane operation step.

In this normal operation, the SS of the fish water 111 in the fish tank 30 is
and the ammonia concentration gradually decreases as shown in FIG. The SS concentration gradually decreases from Co and is maintained at a constant value C1. The ammonia concentration gradually decreases from AO and is maintained at a constant value A.

This constant value A1 is the limit concentration that does not inhibit the growth of the fish 112. In addition, a constant value CI is a concentration that does not inhibit the growth of pathogenic bacteria in a short period of time.

The concentration is such that microorganisms such as mold are present, making long-term operation dangerous. Therefore, in this state, the next UF membrane operation step will be started.

(2) UF membrane operating process If the normal operating process described above is continued for a long period of time, microorganisms such as pathogens and molds in the fish farming water 111 will proliferate in large quantities because the fish farming water 111 is aerated. In addition, micro SS is fish culture water 1
As the SS remains in the fish water 111, it becomes larger due to aeration, and the SS concentration in the fish culture water 111 gradually increases. This process uses these microorganisms.

This is a step of removing minute SS.

First, the pump 56 is stopped by a timer operation, and the on-off valve 90 is closed. Next, the on-off valves 61 and 74 are opened to operate the pump 56. The liquid in the storage tank 44 is transferred to the pipe 55. Pump 56. Tube 57. 58. 59, 60. Open/close valve 61.
Tubes 62a and 62b.

Sponge ball collector 63. tube 62c, UF membrane module 64. Tube 70. Sponge ball collector 71, tube 72.
Same 73. Open/close valve 74. Tube 75. 76, control valve 77, pipe 78. Flow meter 79. It is returned to the storage tank 44 through the pipe 80 and circulated therein.

The water that has been cross-flow filtered and sterilized by the UF membrane module 64 is sent to the pipe 83. Flow meter 82. The water is returned to the fish tank 30 through the pipe 84 in order, and the UF membrane module 64 is operated in circulation.

This circulation operation is performed for t2 hours as shown in FIG.

As shown in FIG. 2, in this step, the SS concentration of the fish culture water 111 gradually decreases from the value C1 to the value C2 and becomes constant. Also, the ammonia concentration hardly changes. The value C2 is SS
The concentration is below the detection limit and contains almost no microorganisms such as pathogenic bacteria and mold. Therefore, at this concentration, the fish 112 in the fish culture tank 30 can grow extremely normally without getting sick.

Furthermore, when this UF membrane operation step is completed, the process returns to the normal operation step, and these two operations are performed alternately.

As shown in FIG. 2, by alternate operation, the ammonia concentration can be maintained at the A1 value that does not inhibit the growth of the fish 112, and the SS concentration can be maintained at the C2 to C1 value, so that the fish 112 can be reared intermittently.

(2) UF membrane cleaning step With the cross-claw filtration in the UF membrane operating step, solids in the stock solution accumulate on the stock solution side of the UF membrane to form a cake layer. This cake layer reduces the filtration flux and reduces the filtration rate. This process is aimed at recovering flux.

First, after the UF membrane operation step is completed, the on-off valve 61. Same 74. Closing 90, 94. Same 9
9 to operate the pump 56.

By this operation, the water flow inside the UF membrane module 64 is reversed, and the concentrate outlet side now becomes the inlet side. This flow causes the sponge balls 102 stored in the sponge ball collector 71 to flow through the UF membrane module 64, thereby peeling off the cake layer. The sponge ball 102 is placed in the sponge ball collector 63 again. Here, the pump 56 is stopped, the on-off valves 94 and 99 are closed, and the on-off valves 61. Same 7
4 is opened to operate the pump 56, the flow is reversed again and the sponge balls 102 move from the sponge ball collector 63 to the same 71. The flux is restored by repeating this operation about 5 to 20 times.

This step is performed with a timer at a frequency of 1 to 3 times/day.

Further, the sediment in the lower part of the storage tank 44 is periodically drained through the pipe 52 by opening the on-off valve 51.

■ Fixed bed cleaning process This process is a process of peeling off and cleaning excess biofilm adhering to the filter bed 46 and support material 47 of the fixed bed 41, and restoring the flow rate passing through the fixed bed 41, that is, the amount of water in the pipe 54. be.

First, the on-off valves 38 and 42 are opened, and the fish culture water 111 is supplied into the storage tank 44. When the liquid in the storage tank 44 overflows through the pipe 50, the on-off valves 42 and 85 are opened, all other on-off valves are closed, and the pump 56 is operated. By this operation, the liquid in the storage tank 44 is supplied to the bottom of the fixed bed 41, thereby generating an upward flow in the filter bed 46. The biofilm peels off due to contact between this upward flow and the biofilm. The detached biofilm is sent to the storage tank 44 and settles at the bottom thereof.

Thereafter, by closing the on-off valves 42 and 85, stopping the pump 56, and opening the on-off valve 51, the sediment in the lower part of the storage tank 44 is drained.

Furthermore, the on-off valve 38. Same 53. Open the same 90 and pump 5
6 and return to the normal operation process, or open/close valve 38.
Same 53. 61. Open the same 74 and operate the pump 56,
Return to the UF membrane operation step and restart the operation.

As explained above, according to this embodiment, the following effects can be obtained.

(1) Since the fixed bed 41 is used as the biofilm treatment tank, nitrification occurs as well as the removal of organic matter, making it possible to remove harmful substances such as ammonia, nitrite, and organic matter to fish.

Moreover, relatively coarse SS which is larger than the gap between the three materials can also be removed.

(2) Since the UF membrane module 64 used as a pressure-driven separation membrane has a large filtration area, a high flux can be maintained and pathogens can be efficiently removed.

(3) The storage tank 44 and pump 56 are in normal operation, UF
In addition to membrane operation, fixed bed 41 and UF membrane module 64
It can also be used for backwashing, so there is no need to install a new tank or pump for backwashing.

(4) Since the on-off valve is configured as an automatic on-off valve, it is easy to control opening and closing.

(5) Since sponge ball cleaning is used to clean the UF membrane module 64, the filtration part will not open for a long period of time.

Note that the present invention is not limited to the embodiment shown in FIG. 1, but includes other embodiments as follows.

The biofilm treatment tank is not limited to the fixed bed 41, but may be a fluidized bed.

A swollen bed may be used, and it does not matter whether it is aerobic or anaerobic. Furthermore, the backwashing mechanism and peeling method are not limited to those shown in Fig. 1, and the aeration method 1
Mechanical stirring, etc. is possible.

Further, the pressure-driven separation membrane is not limited to the UF membrane, and hollow fiber membranes and reverse osmosis membranes (RO membranes), which are microfiltration membranes, can also be applied.

Furthermore, the number of the biofilm treatment tank and the pressure-driven separation membrane is not limited to one each. A plurality of them can be combined in parallel or in series.

In addition, it is also possible to use the above biofilm treatment tank and pressure-driven separation membrane in combination with other treatment techniques.

In other words, it is also possible to combine these two treatments with treatments such as ozone, ultraviolet rays, or soil treatment.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a highly reliable fish farming water purification device that can remove pathogenic bacteria and mold from fish farming water and allow fish to grow normally.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of a fish farming water purification device according to the present invention, Fig. 2 is an explanatory diagram showing the operation process in the same embodiment, and Fig. 3 shows an example of a conventional fish farming water purification device. It is a schematic block diagram. 30... Fish culture tank 41... Biofilm treatment tank (fixed bed) 64... Pressure-driven separation membrane (UF membrane module) 111
...Fish water

Claims (1)

[Scope of Claim] A fish farming water purification device comprising: a biological treatment tank for biologically treating fish farming water; and a pressure-driven separation membrane module for filtering pathogenic bacteria, mold, etc. contained in the fish farming water after biological treatment.