JP2011130685A - Closed circulation type culture method for fishes or shellfishes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for rearing fishes or shellfishes (cultured fishes) in a closed circulation type culture apparatus, by which the installation can be simplified to more largely lower the cost of the installation, and labors and costs for operation maintenance than those of conventional techniques, and the characteristic smells and flesh qualities of the cultured fishes can remarkably be improved. <P>SOLUTION: The method for rearing the cultured fishes or shellfishes in the closed circulation type culture apparatus for the fishes or shellfishes with a membrane separation activated sludge treatment device as a main device for separating or degrading suspended substances and excretory substances from circulated water containing left feeds and feces extracted from rearing tanks, and ammonia, organic feces, and the like excreted from reared fishes, includes adding particular activated carbon to an aeration tank of the membrane separation activated sludge treatment device and operating the culture device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an aquaculture method using a closed-circulation aquaculture device that raises seafood while purifying and circulating water in a breeding tank through a purification device. More specifically, the membrane-separated activated sludge treatment device is a device that decomposes and removes ammonia and organic excreta excreted by fish and shellfish, and cultivates edible fish and shellfish in aquaculture tanks on land by circulating the breeding water. The present invention relates to an aquaculture method using a closed circulation culture apparatus.
Background art

  Conventionally, on-shore aquaculture of edible fish and shellfish is drained while supplying a large amount of seawater or seawater-penetrated water into which the seawater has penetrated into the ground on land close to the sea. This is done by the “flowing method”. Alternatively, on the land adjacent to a river or lake, etc., it is carried out by a “flowing method” in which river water, lake water, groundwater, or the like is pumped and drained while being supplied to a breeding tank. The wastewater contains organic waste such as food residue, feces, and viscous substances. Therefore, especially when facing confined waters, it causes pollution of the seas and lakes, and not only has a significant adverse effect on the nearby natural biota, but also the farms that are pumped up as breeding water itself. As a result, it will be affected by the occurrence of fish diseases and poor growth.

  Furthermore, in the conventional “run-off method”, fish disease and bacteria that cause fish disease sometimes survive in the intake water, so fish disease often occurs and is seriously damaged. Especially recently, environmental pollution in the surrounding water area has generally progressed, and as a result, the number of causative bacteria for fish diseases has increased, causing serious damage to the aquaculture industry. In response to such problems, in addition to chemical substances that promote growth, pharmaceuticals such as synthetic fungicides and antibiotics are used in a considerable amount to combat fish diseases. In addition to problems, the release of chemical substances and pharmaceuticals into the environment is also a problem.

  In addition, it was difficult to cultivate seawater fish and shellfish at a place away from the sea with the “pour-off method”. Furthermore, when cultivating warm-water fish and shellfish such as shrimps, or when trying to maintain the optimum water temperature for the growth of fish and shellfish, the “pour-off method” has a problem that it requires a lot of energy for temperature control. It was.

  Therefore, in recent years, as a method that can solve the above-mentioned problems, various research and development related to closed-circulation aquaculture technology that uses purification water while circulating breeding water has been promoted. Production is starting to take place.

  Conventionally developed closed-circulation aquaculture devices are basically composed of the following devices. That is, the breeding water extracted from the breeding tank is introduced into the foam separation device via a sedimentation tank or a physical filtration device for removing suspended substances. Liquid cyclones and drum filters are used for physical filtration. The foam separation device removes fine suspended substances such as proteins and lipids, and the substances removed together with the foam are discharged out of the system. The breeding water that has passed through the foam separation device is subjected to biological treatment for the purpose of decomposing organic matter, and further supplied to a nitrification device that detoxifies ammonia excreted by the breeding fish. Biological treatment is used to decompose BOD and ammonia on tank surfaces filled with plastics and inorganic carriers, and on the carrier surfaces such as filter layers using sand and anthracite as filter media used for water purification treatment. Biological filtration is used to propagate microorganisms that act efficiently. The breeding water subjected to nitrification passes through the ultraviolet sterilization treatment device via the temperature control device, the dissolved oxygen concentration is adjusted by the oxygen infusion device, and is supplied to the breeding tank.

  Generally, the amount of breeding water is circulated so that the total amount of breeding water in the tank is changed once in 1 to 2 hours. In addition, if fresh water of about 5% of the breeding water is supplied and replaced, the nitrate ion concentration produced by nitrification of ammonia can be maintained at a level that does not affect the breeding fish. Is considered unnecessary. Furthermore, it is said that when the system is operated for a long period of time in a closed circulation culture method, the color of the breeding water advances. If it is difficult to replace breeding water, install a device to denitrify some circulating water in parallel with foam separation-biological treatment-nitrification treatment, and turn the treated water into circulated water after nitrification treatment A method of joining has also been proposed. Alternatively, there is a method in which BOD decomposition and nitrification are simultaneously performed in a biological filtration tank having sufficient capacity.

  Therefore, in the conventional closed-circulation aquaculture, in order to separate feces and residual food (residual food) and decompose metabolites such as ammonia, a complicated and large-scale purification treatment apparatus as described above is used. A combination is needed. As a result, there is a problem that construction costs and operation management costs are high, making it difficult to reduce the production cost of cultured fish. The operation of a large number of various facilities requires not only power costs but also excessive labor costs as well as repair equipment costs for maintenance. In particular, in the case of marine fish that require breeding water with a seawater composition, maintenance of metal parts, electrical systems, etc. becomes an important issue due to its corrosive nature. Furthermore, water exchange is one of the factors that increase the production cost of farmed fish. In other words, the cost of supplying fresh water is necessary. Especially in the case of land-based closed-loop culture using artificial seawater in consideration of the environment, the cost of salt used for artificial seawater is comparable to the production cost of cultured fish. Will occupy.

  In the case of closed-circulation aquaculture, in principle there is no risk of fish disease unless bacteria and viruses that cause fish disease are brought into the breeding water. However, because young fish or young fish potentially carry bacteria and viruses that cause fish disease, it is required to be kept economically at a high density, and depending on the fish species, the environment in which bacteria can easily grow Because it is driven by and fully fed, there is a problem that bacteria and the like are likely to grow. Therefore, conventionally, an ultraviolet germicidal lamp or an sterilization method using ozone treatment is often used.

  However, sterilization by ultraviolet rays has a limited effect in environments where there are many suspensions or organic matter that absorbs ultraviolet rays, such as breeding water. There is a problem that the sterilization effect is uncertain due to the influence of fluctuations in the concentration of organic matter. Also, although ozone has a high sterilizing ability, unlike breeding water, such as tap water, when BOD load is high, it is spent on the decomposition of BOD, ie organic matter, bromine and iodine in the seawater composition, etc. Reacts with other substances to produce various substances that adversely affect organisms. Therefore, it is necessary to finely adjust the amount of ozone added, and it is also necessary to add a process and equipment for treating such by-products by ozone treatment. Therefore, not only is the ozone generator expensive, but the cost further increases.

  Furthermore, it is a problem of cultured fish that is common to fish bred in the “flow-off method”, but especially in the case of fish bred in a closed-circulation culture method, It is said to be inferior. The reason for this is thought to be that the difference in the quality is due to the lack of movement of the cultured fish, and the difference in odor is thought to be due to the quality of the breeding water derived from the purification method of the circulating water However, it has not been confirmed yet.

  For example, according to the aquaculture device of Patent Document 1, the entire amount of water drawn from the breeding aquarium is introduced into the settling tank to separate sludge, and then passes through a pair of foam separation tank and nitrification tank. And after this, a part is returned to a sedimentation tank through a denitrification tank, and the remainder is returned to a breeding tank through an ultraviolet sterilizer. That is, all of the water returning to the breeding tank undergoes ultraviolet sterilization.

  In addition, as an example of implementation in this known example, highly concentrated water containing solids taken out from the lower part of the precipitation tank is separated by “solid-liquid separation means” using a filtration membrane, and then the separated water is separated. It shows how to return to the settling tank. In addition, in paragraph 0023 of Cited Document 1, since the hollow fiber membrane does not pass nitrifying bacteria and denitrifying bacteria, the activated sludge containing nitrifying bacteria and denitrifying bacteria is allowed to inhabit the portion outside the filtration membrane inside the separation tank. However, there is no description or suggestion about the operation method of adding activated carbon to the outer part of the filtration membrane.

  The aquaculture device of Patent Document 1 requires a large-scale ultraviolet sterilizer and a large-scale nitrification tank that allows the entire amount of circulating water to pass through. Therefore, it is difficult to reduce the equipment cost and the operation cost.

  On the other hand, Patent Document 2 employs a “precipitation tank” that produces a spiral flow and performs solid-liquid separation by centrifugal force as a precipitation device, and a “filter device” that includes a plastic net, etc. In addition, a purification device called a “biofilter (biological filtration tank)” made of a filter medium to which nitrifying bacteria or the like are attached is used. A heat pump is used for temperature adjustment. In the apparatus of Patent Document 2, the “biofilter (biological filtration tank)” apparatus is considerably large, which increases the cost, and also requires an ultraviolet sterilizer for passing the entire amount of circulating water. It is necessary to separately process the solid residue separated in “2.

  In Patent Document 3, “organic wastewater generated from fishing ports, fish markets, land farms, etc.” is introduced into a “membrane separation activated sludge treatment tank” and treated, and then treated water separated by a filtration membrane is used. In addition to discharging, it is described that surplus sludge is discharged into aquaculture tanks for treatment. According to the method of patent document 3, while processing the high concentration organic waste water in a fishing port, the excess sludge generated in this case can also be processed. However, this technique is suitable for treating a relatively small amount of high-concentration wastewater, and is not suitable for treatment by circulating a large amount of breeding water as in closed circulation culture. Moreover, no mention is made of a method of operating by adding activated carbon to the “membrane separation activated sludge treatment tank”.

In recent years, the membrane separation activated sludge treatment method has been gradually adopted in the fields of sewage treatment and industrial wastewater treatment (Non-Patent Document 1). However, as shown in Tables 4.2 and 4.5 of Non-Patent Document 1, in an operating environment of a general membrane separation activated sludge treatment apparatus (MBR: membrane bioreactor), the BOD volumetric load is several tens to several thousand g / m ^3. Therefore, high concentration BOD loading is considered as one of the essential conditions. Further, the internal MLSS (Mixed liquor Suspended Solid) in the activated sludge treatment tank (aeration tank) is several hundred to tens of thousands mg / L under general operating conditions.

However, the BOD volume load in the breeding water in the closed-circulation aquaculture method is several mg / L, which is much lower than the raw water treated by the membrane separation activated sludge method, which is usually practiced. When applied to the closed circulation culture method breeding water treatment, the internal MLSS will be 100mg / L or less. When the membrane separation activated sludge treatment device is operated with such extremely low MLSS, the suspended particles made of activated sludge ride on the upward flow driven by aeration and have the effect of washing the clogged layer on the membrane surface. It was not expected and clogging of the separation membrane was very likely to occur, and long-term stable operation was very difficult, and thus it was considered that it could not be applied to such treated raw water. Furthermore, there are almost no examples of applying the membrane separation activated sludge method to treated raw water having a high salt concentration such as seawater, and it was unclear whether it could be applied to breeding water having a seawater composition.

  That is, even if Patent Document 1 suggests that the membrane separation activated sludge method can be partially combined, it has been considered that practical use is difficult. For this reason, other than Patent Document 1, there is no known example suggesting that the membrane separation activated sludge method is applied to the closed circulation culture method. In addition, the proposal of patent document 1 arrange | positions a membrane-separation activated sludge processing apparatus in the high concentration sedimentation separation water of the collection system of a sedimentation tank in parallel with a nitrification tank.

  On the other hand, there is Non-Patent Document 2 as an example in which a technique considered to be a membrane separation activated sludge method is applied to a low concentration BOD. In this known example, biological activated carbon that is widely applied to the removal of trihalomethane and odorous substances in raw water in tap water purification treatment is applied, and turbidity and bacteria in the water are removed by immersion membrane filtration. It relates to experiments aimed at confirming the effect of the combination of biological activated carbon and membrane filtration on raw water for quality water purification. At that time, it diffuses for the purpose of creating a circulating flow that rises between the submerged membrane elements, and in addition, intermittently diffuses the dead water part to prevent the deposition of biological activated carbon, and happens to be membrane-separated activated sludge treatment. It was found and reported that it effectively works to suppress clogging when operated under the same conditions as the law. However, there is no mention or suggestion as to whether such a method can be applied to the purification of circulating water in closed-circulation aquaculture methods containing viscous substances and proteins excreted by domestic fish. Furthermore, there is no description that reminds us that, when activated carbon is added, the quality and smell of cultured fish are remarkably improved and no need for water replacement.

   In view of the above situation of the closed-circulation aquaculture method, we first developed a membrane-separated activated sludge method that has been greatly simplified by omitting the equipment that constitutes the conventional closed-circulation aquaculture device. A device for decomposing and removing ammonia and organic excreta excreted by fish and shellfish, circulating the breeding water and cultivating edible fish and shellfish in an aquaculture tank at a high density, equipment cost, operation maintenance and management A new closed-circulation aquaculture device and aquaculture method that significantly reduce costs were proposed. The present invention further improves this.

JP2002-223667 Patent 3769680 JP2005-074420

"Membrane Bioreactors for Wastewater Treatment" T. Steph enson, K. Brindle, S. Judd, B. Jefferson; IWA publishing, 01 June 200 0; ISBN: 9781900222075. : Koji Ishida, Shuzo Matsumura, Kiyoji Izumi; Japan Environmental Education Center, 2003.3.) “ACT21 3rd Research Committee Bring Research Final Report, Research on Biological Activated Carbon / Membrane Filtration System” (Water Technology Research Center, April 2002).

  The present invention has been made in view of the above problems, and provides an aquaculture method that significantly improves the quality and texture of fish produced using a closed circulation culture device. , Providing an improved operation method for a closed-circulation aquaculture system for seafood that uses a membrane-separated activated sludge process, which greatly simplifies the equipment configuration, to decompose and remove ammonia and organic excreta excreted by seafood To do.

  The present invention provides a membrane-separated activated sludge as an apparatus for separating or decomposing suspended substances and excreted substances from breeding water including residual food extracted from the breeding tank, feces and ammonia and organic excretions excreted by the breeding fish. When operating a fishery product closed circulation culture device equipped with a treatment device (MBR: membrane bioreactor), it is operated by adding particulate activated carbon to the aeration tank of the membrane separation activated sludge treatment device.

  As a closed-circulation aquaculture device for seafood equipped with a membrane-separated activated sludge treatment device, a sedimentation suspension material consisting of a rearing aquarium for rearing seafood and residual food or feces drawn from the lower end of the rearing aquarium A storage tank that temporarily stores a large amount of waste water, a membrane-separated activated sludge treatment device that purifies untreated breeding water drawn from the storage tank disposed downstream thereof, and a purified treated water disposed downstream thereof A closed-circulation aquaculture device equipped with a temperature-adjusting tank having a temperature control function and an oxygen infusion device for adjusting the dissolved oxygen concentration of the treated water fed from the conditioning tank and supplied to the breeding tank The present invention can be applied.

  Alternatively, a rearing tank for rearing seafood, a first suspended solids separating device for separating the drainage drawn from the lower end of the rearing tank into a liquid composed of sedimentary suspended solids and a primary supernatant, and an upper part of the rearing tank A second suspended solids separator for separating the suspended sediment in the breeding water extracted from the suspension and the remaining suspended suspended matter in the primary supernatant into a secondary supernatant; and the secondary supernatant. A distribution mechanism that distributes to the first to third distribution channels, a water tank that is disposed downstream of the second distribution channel, and includes activated sludge for treating ammonia, and suspended suspended solids and bacteria from the activated sludge-treated water. A membrane separation activated sludge treatment device (MBR) comprising a filtration membrane for separation, and a filtration membrane for separating suspended suspended solids and bacteria from the secondary top, which is arranged downstream of the third branch channel A membrane filtration device, a membrane separation activated sludge treatment device, and An adjustment tank that is disposed downstream of the membrane filtration device and stores treated water that has been purified; a reflux water supply port that forms the downstream end of the third branch channel and returns the secondary supernatant into the breeding water tank; A treated water return path for returning treated water in the tank to the breeding water tank, and an untreated water reservoir for storing the secondary supernatant, the primary supernatant, or the waste water, disposed upstream of the membrane separation activated sludge treatment apparatus. If it is a closed circulation culture device which consists of a tank, it can apply more preferably. With such a closed-circulation aquaculture device, it is possible to make the facility scale of the minimum membrane separation activated sludge treatment device commensurate with the amount of ammonia and organic waste to be treated, and at the same time, in the aeration tank Since the activated sludge concentration can be increased by increasing the concentration of organic matter supplied to the product, the amount of activated carbon added can be reduced to further reduce the production cost.

  The closed-circulation culture method for seafood of the present invention uses the closed-circulation culture apparatus described in the preceding paragraph (paragraph 0027) and immediately after feeding and / or during the period corresponding to the peak of excretion, from the adjustment tank to the breeding aquarium. The water level of the rearing tank is increased by increasing the amount of wastewater from the lower part of the breeding tank and increasing the amount of drainage between the amount of treated water and the amount of drainage during the period corresponding to the peak. Of course, there is no problem even if the vehicle is operated with increasing or decreasing. By controlling the amount of treated water supplied and discharged in proportion to or corresponding to water quality fluctuations (proportional control method), circulation during times when the concentration of substances to be treated, such as ammonia and organic excreta in untreated water, is low Since the amount of water sent to the membrane-separated activated sludge treatment apparatus can be reduced, the concentration of organic matter supplied into the aeration tank can be further increased to maintain the activated sludge concentration high. Therefore, when the present invention is adopted in combination with the operation method based on such a proportional control method, the membrane separation activated sludge treatment device (MBR) can be further miniaturized and the activated sludge concentration can be increased. Since the amount of activated carbon to be reduced can be further reduced, further cost reduction is possible.

  The closed-circulation culture method for seafood of the present invention is based on the amount of treated water containing activated carbon in the aeration tank in the aeration tank of the membrane separation activated sludge treatment apparatus provided in the above-mentioned closed-circulation culture apparatus. The dry carbon weight is 0.2 to 5.0%, preferably 0.4 to 2.5%. Since the particulate activated carbon is confined in the aeration tank, it is basically lost by being contained in the mist scattered with the aeration air, or it is crushed by the movement in the aeration tank and only functions as pulverized coal. Therefore, the rate of loss of particulate activated carbon is very small, but it can be sufficiently maintained and managed by appropriately supplementing the decrease.

  As the particulate activated carbon, granular activated carbon or powdered activated carbon used for the purpose of removing impurities in tap water purification or drinking water is preferably used. The activated carbon may be dry charcoal or wet activated carbon. The size of the particulate activated carbon is 20 mesh or less, preferably 100 mesh or less, and the cake layer is generated on the membrane surface without damaging the membrane surface of the MBR by riding on the water flow without settling in the aeration tank. Any material can be used as long as it can scrape off and prevent clogging of the film. From this point of view, soft wood-based powdered activated carbon which is hard to settle is particularly preferably used. In addition, when the particle size of particulate activated carbon is too small, the force which scrapes off the cake layer produced | generated on a film | membrane surface is weak, clogging of a film | membrane cannot be suppressed, and it is thought that it does not function well. Further, if the particle size is too large, it tends to settle, and it is difficult to flow in the aeration tank by riding on the water flow caused by aeration, and it is considered difficult to function to suppress clogging of the membrane.

  However, even if it is other than the above, there is no eluate that adversely affects domestic fish and humans, and it can be used if it is used in, for example, food production processes and has the above characteristics can do.

  According to the closed-circulation culture method for seafood of the present invention, the quality of the domesticated fish is improved and the smell peculiar to the cultured fish disappears compared to the cultured fish produced by the closed-circulation culture method according to the prior art. It is possible to produce cultured fish with a significantly improved texture.

  Furthermore, according to the closed-circulation aquaculture method for fish and shellfish of the present invention, the replacement of fresh water required in the closed-circulation aquaculture method is almost unnecessary. It is possible to greatly reduce the salt supply, which is a substantial proportion of the production cost, and to further reduce the production cost.

  In addition, according to the closed circulation culture method for seafood of the present invention, ammonia and organic excrement, suspended matter such as residual food and feces can be supplied to the membrane separation activated sludge treatment device and used as activated sludge, Since water exchange is virtually unnecessary, the amount of waste such as wastewater sludge discharged outside the system decreases to a level that can be ignored.

It is a block diagram which shows the basic composition of the closed circulation culture device applied preferably to one Embodiment of this invention. It is a typical section perspective view showing the example of composition of the 1st and 2nd hydrocyclone in the closed circulation type aquaculture device of Drawing 1.

  A closed circulation culture device that is preferably applied to an embodiment of the present invention will be described with reference to FIGS. The closed-circulation aquaculture apparatus 10 of the present embodiment is provided for each of the breeding aquariums 1-1, 1-2, and each of the breeding aquariums 1. First liquid cyclones 2-1, 2-2, etc. that receive the concentrated suspended solids, ie, sludge suspension B, and the supernatant discharged from the first liquid cyclones 2-1, 2-2, etc. (primary (Supernatant) C and one second liquid cyclone 3 that receives the breeding water A taken from each breeding tank 1-1, 1-2, ..., and the supernatant discharged from the second liquid cyclone 3 (secondary supernatant) A distribution mechanism 8 that distributes E to the first to third branch channels 81, 82, and 83, an untreated water storage tank 4 that is disposed at the downstream end of the second branch channel 82, and a membrane separation activated sludge downstream thereof Treatment device (MBR) 5, membrane filtration device 6 arranged at the downstream end of the third branch 83, purified water S from the membrane separation activated sludge treatment device 5, and membrane from the membrane filtration device 6 Filtered water I Is composed of an adjustment tank 7 for receiving and storing oxygen, and an oxygen infusion device 9 downstream thereof.

  The breeding tanks 1-1, 1-2,... Are gently inclined so that the bottom surface becomes deeper toward the center or a specific location, and the sludge suspension is formed in the deepest part thus formed. A discharge pipe 12 is connected. The rearing tanks 1-1, 1-2,... Are preferably circular, elliptical, or regular polygons such as regular octagons.

  In the present specification, for the sake of convenience, what is mainly separated by the first hydrocyclones 2-1 and 2-2 will be referred to as “sedimentable suspended matter” or “sludge”. That is, suspended matter (SS) floating in the water derived from residual food (food feed) or feces, etc., that can be collected from the bottom of the rearing tank 1-1, 1-2,. Will be referred to as “sedimentable suspended matter” or “sludge”. In addition, suspended substances other than “sedimentable suspended substances” will be referred to as “floating suspended substances”.

  In the upper part of the first hydrocyclone 2-1, 2-2,..., A sludge suspension B containing sludge at a high concentration flows in the tangential direction through the sludge suspension discharge pipe 12. From the lower ends of the first hydrocyclones 2-1, 2-2,..., Sludge M is sent to the untreated water storage tank 4 through the sludge discharge pipe 24. The sludge suspension J containing the sludge remaining in the supernatant water is also sent to the untreated water storage tank 4 from the lower end of the second hydrocyclone 3 through the sludge / SS discharge pipe 34.

  FIG. 2 schematically shows a configuration example of the first hydrocyclone 2-1, 2-2... And the second hydrocyclone 3. The second hydrocyclone 3 is larger than each first hydrocyclone 2, and has an inner diameter of 1.5 to 4.0 times, for example. The inner diameter of the first hydrocyclone 2 is, for example, 0.3 to 0.6 times the inner diameter of the rearing tanks 1-1, 1-2,.

  The first hydrocyclone 2 and the second hydrocyclone 3 can be appropriately provided with baffles on the inner wall surface. The baffle plate can be provided with an axially extending inner wall of the conical portion, and the cylindrical portion can be provided with a spiral or the like for enhancing the spiral flow. In particular, when the sedimentary suspended solids are difficult to settle, a baffle plate can be appropriately disposed.

  The primary supernatant C is discharged from the first hydrocyclones 2-1 and 2-2 to the second hydrocyclone 3 through the intercyclonic pipe 23. Also, the breeding water A is sent to the second hydrocyclone 3 through the breeding water discharge pipe 13 from the upper part of the breeding tanks 1-1, 1-2,. Here, as shown in the example of FIG. 2, the intercyclonic pipe 23 is joined to the breeding water discharge pipe 13, and the primary supernatant C and the breeding water in the breeding tanks 1-1, 1-2. A mixed supernatant D mixed with A is introduced tangentially into the upper part of the second hydrocyclone 3.

  The secondary supernatant discharge pipe 32 from the second hydrocyclone 3 is connected to the first three-way valve 85, and the first three-way valve 85 returns to the breeding tank 1-1, 1-2,. It is divided into the other flow path 81 and the other. The secondary supernatant G distributed to other than the first branch 81 is divided into a second branch 82 and a third branch 83 by a second three-way valve 86. The first and second three-way valves 85 and 86 and the third three-way valve 87 described later are preferably electric three-way valves, and may be electromagnetic three-way valves, manual valves, or a combination thereof.

  The membrane separation activated sludge treatment device (MBR) 5 was sent to the second branch 82 through the untreated water supply pipe 45 from the lower portion of the untreated water storage tank 4 to the sludge suspensions M and J. Next, a mixed liquid to which the supernatant N is added is supplied.

  The membrane separation activated sludge treatment apparatus (MBR) 5 includes an activated sludge treatment tank containing activated sludge, a separation membrane module immersed in the treatment tank, and a pump for sucking treated water through the separation membrane. The separation membrane here does not allow permeation of bacteria as well as fine suspended substances, and is preferably capable of removing most viruses.

  The activated sludge is composed of nitrified activated sludge that decomposes ammonia, and nitrified activated sludge that is adapted to seawater is used. Preferably, highly active digestion activated sludge obtained by a method (WO00 / 077171) for producing reduced-volume seawater-fed nitrification sludge developed by Vicom Corporation is used. The activated sludge exhibits high digestive activity even in fresh water.

  The manufacturing method of seawater-adapted nitrification sludge developed by Vicom Co., Ltd. is based on the nitrification bacteria consisting of a mixed system of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, and other activated bacteria. A method for producing a reduced-volume seawater-fed nitrification sludge containing a high concentration, comprising the following steps A-E. A: The activated sludge for human waste is diluted with seawater and added with digestion desorption liquid and / or sludge dehydrated filtrate generated at a sewage treatment plant, so that the concentration of ammonia is 100 to 300 mg / liter. In addition, when necessary, the pH is adjusted to 8.5 or less by adding dilute sulfuric acid to this seawater-diluted sludge. B: Prepare a mixed salt / water solution containing 0.4 to 0.8 mol of sodium bicarbonate to 0.4 to 0.7 mol of sodium carbonate. C: For 1 to 3 months, the seawater-diluted sludge was maintained in a single culture tank by (1) monitoring the pH and adding the mixed salt aqueous solution appropriately to maintain the pH at 7.5 to 8.5. 2) Adjust the amount of aeration so that the dissolved oxygen is 2-5mg / liter, (3) Keep the temperature at 20-40 ° C, and (4) Sequentially, the ammonia concentration will be 100-300mg / liter. As described above, the digestion and desorption liquid and / or the sludge dehydrated filtrate are added, and seawater is added as necessary. D: Nitrification with nitrifying bacteria attached around nuclei (for example, 20-100 μm granules) containing persistent organic matter derived from the killed bacteria. Bacterial flocs (eg 50-100 μm in diameter) are formed. E: By precipitating this nitrifying bacterial floc, the reduced volume of seawater-adapted nitrifying sludge is obtained. For example, activated sludge for human waste contains about 0.35% of nitrifying bacteria, and the seawater-adapted nitrifying sludge contains digestive bacteria at a content of about 10 times that of nitrifying bacteria. For example, the volume is reduced to 1/3 to 1/4 of the activated sludge for human waste. By adopting the above "proportional control method" and using such highly reduced seawater-adapted nitrification sludge, nitrification is highly efficient even under conditions where the ammonia concentration is much lower than that of normal sewage treatment. Processing can be performed.

  However, the nitrifying activated sludge used in the present invention is not limited to the above-mentioned seawater conditioned nitrifying sludge.

  The separation membrane module of the membrane separation activated sludge treatment apparatus (MBR) 5 may be either a flat membrane type or a hollow type. The flat membrane type separation membrane module is composed of a membrane element in which a spacer for securing a filtered water passage is wrapped with a flat filtration membrane (flat membrane), folded into an envelope shape, and the end is liquid-tightly sealed. A tube for collecting filtered water is attached to the upper end of the membrane element. A large number of such membrane elements are stacked so as to sandwich a spacer, and the membrane module is stacked at a constant interval. Aeration air supplied to the activated sludge rises through the gaps between the membrane elements immersed in the activated sludge treatment tank. In this way, by generating an accompanying flow in the water in which the activated sludge is suspended, the sludge deposit layer (cake layer) generated on the surface of the membrane element is washed away. In other words, the filtration rate is maintained at a constant level by such an effect.

  The hollow fiber type separation membrane module is configured to open both ends or one end of hollow fibers collected in a bundle and suck the filtered treated water into the hollow fiber membrane from the side of the hollow fiber membrane. Normally, a hollow fiber membrane module is installed in the vertical direction, and the sludge accumulation layer (cake layer) is washed away by the upward flow of aeration air similar to the above.

  In the present invention in which particulate activated carbon is added to the aeration tank, a membrane separation activated sludge treatment apparatus (MBR) comprising a flat membrane membrane module is more preferably applied. In the case of a hollow fiber type separation membrane module, the pulverized coal contained in the particulate activated carbon often enters the close parts of the both ends of the hollow fiber membrane and is difficult to remove even with a washing operation, etc. Therefore, the membrane separation activated sludge treatment device (MBR) consisting of a flat membrane membrane module is easier to use.

  When sludge containing a predetermined amount or more of particulate activated carbon is stored in the activated sludge treatment tank, it can be discharged from a discharge valve 54 provided in the activated sludge tank.

  In addition, a so-called outside tank type membrane separation activated sludge treatment apparatus (MBR) in which a membrane separation apparatus is disposed outside the aeration tank can also be used. In this method, treated water containing activated sludge extracted from the aeration tank by pump is introduced into a membrane separation device installed outside the tank, filtered water is taken out, and concentrated activated sludge water is returned to the aeration tank for circulation. It is. The method for taking out the filtered water may be a suction type or a pressure type, but the suction type is more preferable because it requires less power cost.

  As for the material of the separation membrane used in the membrane separation activated sludge treatment apparatus (MBR), a separation membrane made of a high molecular weight material is commonly used, but there is no particular restriction on the material. However, those having high strength and excellent chemical resistance are preferred because of their excellent durability. From the viewpoint of durability, a separation membrane made of ceramic is also preferably used.

  The membrane filtration device 6 comprises a filtration membrane similar to that used in the membrane separation activated sludge treatment device (MBR) 5, that is, a microfiltration membrane or an ultrafiltration membrane. The form of the filtration membrane module is the same as that of the membrane separation activated sludge treatment apparatus (MBR) 5. Moreover, as what can be preferably employ | adopted, the thing for hollow fiber type membrane modules, for example, a water purification process, can be mentioned. The hollow fiber membrane module may be a cross flow type as well as a total filtration type. In the case of the all-filtration type, the clogging substances are washed away by performing back-flushing and / or aeration as appropriate at regular intervals. The suspension L that comes out at the time of such washing is sent to the untreated water storage tank 4 together with the sludge concentrate J and the like.

  A simple filter made of a metal mesh, a filter cloth, or the like can be disposed upstream of the membrane filtration device 6 as necessary. This filter is for removing coarse dust. Suspended substances and the like captured by the filter are intermittently backwashed or removed from the system and washed for reuse. Backwash water or washing waste water washed outside the system is returned to the untreated water storage tank 4 or the membrane separation activated sludge treatment device (MBR) 5 for treatment.

  Purified treated water S treated through the membrane separation activated sludge treatment device (MBR) 5 and filtered treated water I treated through the membrane filtration device 6 are mixed treated water U in which they are mixed. While stored in the adjustment tank 7, the temperature is adjusted to a predetermined temperature by a temperature adjustment mechanism 75 attached to the adjustment tank 7. Further, in the treated water recirculation path 84, an oxygen infusion device 9 including an oxygen generator 95 is provided. The oxygen infusion device 9 may be a pressure type, a pressure reduction type (diffuser type or the like), and the oxygen source may be oxygen gas separated by a gas separation membrane (PSA), liquid oxygen, or the like.

  In the illustrated example, a third three-way valve 87 is further provided in the first branch flow path 81, and a branch path 88 extending to the oxygen infusion device 9 extends from there. Appropriately when there is little generation of ammonia, etc. and the ratio of circulating water passing through the membrane separation activated sludge treatment device (MBR) 5 and the membrane filtration device 6 is low, but it is necessary to keep the oxygen concentration in the breeding tank high By controlling the third three-way valve 87, a part of the water F in the first branch flow path 81 is sent to the oxygen infusion device 9.

  In addition, when seawater is used for breeding water and it is necessary to reduce the salinity, replenishment for adjusting the salinity with the adjustment tank 7 or backwash water of the membrane filtration device 6 together with the pH adjuster. Can supply water. Conversely, when it is necessary to increase the salinity, salts can be supplied to the breeding tanks 1-1, 1-2, 1-3, 1-4, or the untreated water storage tank 4. However, from actual operating experience, the salt concentration tends to increase, probably because water is evaporated and lost from the aeration tank, and it is necessary to replenish tap water.

  In the illustrated example, only the suction type attached to the membrane separation activated sludge treatment apparatus (MBR) 5 and the extrusion type attached to the membrane filtration apparatus 6 are arranged as the water flow pump 89. However, in addition to this, one or a plurality of water flow pumps are appropriately arranged as necessary for adjusting the difference in the water level of each water tank.

  In the closed circulation type aquaculture apparatus of the present embodiment, the suspended substance can be efficiently separated and concentrated by the double suspended substance separation apparatus. Therefore, the cultured fish is excreted in the membrane separation activated sludge treatment apparatus (MBR) 5. Efficiently supply organic pollutants such as feces and residual food to stabilize MBR function maintenance, and at the same time, reduce the load on the membrane filtration device 6 to prevent clogging and cleaning operations Can be minimized.

  In the membrane separation activated sludge treatment equipment (MBR) 5, not only the wastes such as ammonia and organic matter are decomposed, but also the bacteria are preyed and killed by the activated sludge. Since it can be removed efficiently, sterilization equipment such as an ultraviolet sterilizer can be omitted or the scale can be significantly reduced. Depending on the breeding method, ultraviolet sterilization equipment may be provided only on the path F in FIG.

  In the closed circulation type aquaculture device of this embodiment, the total amount of the secondary supernatant after removing suspended solids (SS) by the double suspended solids separator is the membrane separation activated sludge treatment device (MBR) 5 or membrane. Instead of sending it to the filtration device 6, it is a system that sends only the amount necessary for removing ammonia, SS, and bacteria. In one preferred embodiment, the amount L of the suspension sent to the membrane separation activated sludge treatment device (MBR) 5 side is 5 to 15% of the amount H of water sent to the membrane filtration device 6. Further, in one preferable operating condition, the amount of water F returning to the breeding tanks 1-1, 1-2,... Of the secondary supernatant E through the first diversion channel 81 and the membrane filtration device 6 Ratio of the amount of water H and the amount of water N sent to the membrane separation activated sludge treatment unit (MBR) 5 side, F / H / N is approximately 4-6% / 39-43% / 53-55% is there.

  Therefore, the equipment cost and operation cost for removing ammonia, bacteria, and suspended solids can be minimized. In order to remove bacteria and suspended suspended solids, not only membrane separation activated sludge treatment equipment (MBR) 5 but also membrane filtration equipment 6 can be used, so membrane separation activated sludge treatment equipment (MBR) 5) is sufficient if it has the capacity and size necessary for activated sludge treatment such as ammonia removal. In addition, about the secondary supernatant which came out through double hydrocyclone device, how much is sent to membrane separation activated sludge processing device (MBR) 5 and how much is sent to membrane filtration device 6 The breeding water drawn from 1 can be determined based on the measurement results by measuring the ammonia concentration, suspended solids (SS), the number of bacteria, and the like.

  In the closed circulation type aquaculture device of the present embodiment, particularly in a time zone in which the generation amount of ammonia and organic excrement is large in the breeding aquarium, wastewater with a high concentration of ammonia and organic excrement is temporarily stored. In addition, since it can be stably sent to the membrane separation activated sludge treatment device (MBR) 5, the efficiency of the activated sludge treatment device can be kept high. Furthermore, since the higher activated sludge density | concentration can be maintained, the particulate activated carbon to add can be decreased.

  In addition, the separation function of sedimentary suspended solids using the above hydrocyclone and the separation function of suspended suspended solids using a membrane filtration device reduce the scale of the membrane separation activated sludge treatment equipment (MBR) and at the same time activate sludge concentration. It is clear from the above description that the functional device is attached to maintain a high concentration in order to function efficiently and is not a necessary condition for applying the present invention. That is, depending on the scale of the entire aquaculture device, even a closed-circulation aquaculture device consisting of a simple process flow that supplies the total amount of circulating water to the membrane separation activated sludge treatment device (MBR), It is clear from the above description that the present invention can be preferably applied even to a closed circulation type aquaculture device provided with only a known physical filtration device or membrane filtration device.

  The closed-circulation aquaculture equipment that uses the membrane separation activated sludge treatment equipment (MBR) and hydrocyclone and / or membrane filtration equipment as the main purification treatment equipment has a simple structure compared to the closed-circulation culture equipment of the prior art. In addition to the ease of maintenance, the number of movable machinery is remarkably small, the use of equipment subject to corrosion such as seawater is remarkably low, and power and maintenance costs can be reduced. Since it is almost unnecessary, the production cost is further reduced.

  Next, the present invention will be described with reference to one example and a comparative example of the present invention, but the present invention is not limited to this example.

This example, 2 tank breeding aquarium capacity 4m ^3, reservoir of the 3.5 m ^3, a membrane separation activated sludge treatment apparatus 8m ³ (MBR), adjustment tank 3m ^3, and membrane area 12m ² membrane filtration Using a closed-circulation aquaculture device with the same configuration as shown in FIGS. 1 and 2 as an embodiment, 500 flounder larvae with an average weight of about 65 g are introduced, and the MBR has 0.65 as dry charcoal. It was operated and bred by adding particulate activated carbon of wt%. During the aquaculture period of this example, there was no water exchange and the artificial seawater concentration increased. Therefore, a pH adjuster was appropriately added to tap water to adjust the concentration. Therefore, there was no breeding water discharged outside the aquaculture system other than water taken out of the system when sampling for water quality analysis and the filtration membrane module was removed and washed. During the breeding period, the ammonia concentration is maintained at 0.1 to 3.1 mg-N / L (ammonia nitrogen amount per liter of breeding water) and the nitrous acid concentration is maintained at 0.00 to 2.3 mg-N / L. The level was satisfactory. In addition, the nitrate ion concentration was 176 mg-N / L on the 90th day of breeding and 268 mg-N / L on the 159th day, 71.6% and 59.4% of the theoretical value estimated from the feeding amount, It was maintained at a value sufficiently lower than the standard value of 600 mg-N /. The reason why the nitrate ion concentration is kept extremely low despite the lack of a denitrification device is not clear, but it is due to the performance of MBR operated by adding particulate activated carbon, or in the storage tank It is presumed that denitrification reaction is taking place or an additive effect of both biological reactions. Throughout the breeding period, the appearance of the breeding water was colorless and transparent. The number of general bacteria was the result of a simple measurement method, but 100% was removed from the membrane filtration device and 99% or more was removed from the MBR. In addition, in the case of this type of closed circulation aquaculture equipment, there are very few devices with drive devices that need to be inspected, monitored, and managed, and daily maintenance management includes feeding fish and observing their condition, and It was confirmed that it was possible to concentrate on water quality analysis and monitoring, and that management work was saved significantly.

  About 150 days later, when the average weight reached about 450 g, the first tasting evaluation was performed. Growth was slowed slightly because the amount of feed was limited for the time of the initial experimental conditions, but there was no problem in confirming the effect of the present invention.

  In the evaluation of the tasting, the feeding was stopped for several days and the animals were reared and then squeezed and sampled one day and night. As a result of selecting panelists from seafood aquaculture specialists, the total number of odors was 19 people, `` I do not feel smell '' 19 out of 20 people, `` I feel smell when I eat '' is 1 person there were. As for the texture, 19 people were “solid” and “slightly soft”, and 1 was “soft”. As for umami, the number of respondents who answered “delicious” and “had umami” was 14 people, “no taste” was rated 4 people, and “other” was 2 people.

  Two months later, 210 days after the start of breeding, a second sample of 720-770g sample fish close to the shipping size was evaluated. As a result, the total number of scents was 7 people, “no scent” was 7 out of 8 people and “smells when eaten” was 1 person. Regarding the texture, 8 people were “solid” and “slightly soft”, and 0 people rated “soft”. As for umami, seven respondents answered that it was “delicious”, “has umami”, and “had a sweetness”, and one was rated as “no taste”.

The comparative examples are 5 40m ³ breeding water tanks equipped with liquid cyclone type sedimentation suspended solids separation device, drum filter type physical filtration device, foam separation device, rotating disk bed type biological treatment device for organic matter decomposition, sand flow A commercial scale closed-circulation aquaculture device consisting of a bed-type ammonia nitrification device, an ultraviolet sterilization device, a temperature-regulating tank, and an oxygen infusion device that dissolves and adjusts oxygen produced by PSA in the breeding water. In use, two tanks with 4,000 flounder per tank, two tanks with 2,000 flounder, and spare flounder for adjusting the number of tails were put into one tank for trial production. During this breeding period, artificial seawater was replenished at a daily water change rate of about 5%. The water quality was controlled within the standard value range for each item, but the appearance was colored and some turbidity was observed.

  Although the growth rate is slightly inferior to conventional experience due to some problems in the adjustment of water quality conditions, there is no problem in comparing the effects of the present invention.

  Although the evaluation was made on a sample basis every 1 to 2 months, the data evaluated when the average body weight reached 450 g for comparison with the examples are as follows. In other words, there was no difference between the data of 4,000 flounder thrown and 2,000 flounder thrown, so both are shown. Panelists and evaluation methods are the same as in the examples. The total number of scents was 17 people out of 25, “no scent”, 5 “a little smell when eaten”, and 3 “a smell when eaten”. Regarding the texture, 21 people out of 26 were “solid” and “slightly soft”, and 5 people rated it as “soft”. As for umami, the number of respondents who answered “delicious” and “had umami” was 18 out of 26, 4 were “not tasteful”, 1 was “tasteless”, and 2 were “bad” One person was "Other".

  Further, in the evaluation of the Japanese flounder that reached about 800 g in the comparative example, although the odor and texture were slightly improved from the above-mentioned 450 g size, the evaluation results were almost the same.

  The above evaluation results show that the cultured fish bred by the method of the present invention is clearly improved in smell, texture and taste.

Claims (15)

  Suspended and excreted substances are separated or decomposed from rearing water, including residual food, feces, and ammonia and organic excretions excreted by the reared fish extracted from the rearing tank of the closed-circulation aquaculture equipment that rears seafood When raising cultured fish using a closed-circulation aquaculture device equipped with a membrane separation activated sludge treatment device as a treatment device, add particulate activated carbon to the aeration tank of the membrane separation activated sludge treatment device and operate. A method of raising seafood characterized by   2. The breeding method according to claim 1, wherein the closed-circulation aquaculture device comprises at least a breeding tank (1) for breeding fish and shellfish, and residual food or feces drawn from the lower end of the breeding tank (1). A storage tank (2) that temporarily stores wastewater containing a lot of suspended solids, a membrane-separated activated sludge treatment device (3) that purifies untreated breeding water drawn from a storage tank located downstream of the storage tank, and its downstream The adjustment tank (4) having a temperature adjustment function for storing treated water that has been subjected to purification treatment, and an oxygen infusion device that adjusts the dissolved oxygen concentration of the treatment water fed from the adjustment tank and supplied to the breeding tank (5). A method for raising seafood, comprising:   2. The breeding method according to claim 1, wherein the closed circulation type aquaculture apparatus is configured to suspend the aquatic tank (1) for cultivating seafood and the drainage (B) drawn from the lower end of the aquarium (1). A first suspended substance separation device (2) for separating the substance-containing liquid (M) and the primary supernatant (C), the breeding water (A) drawn from the upper part of the breeding tank (1), and the above 1 A second suspended material separator (3) for separating the secondary supernatant (C) into a liquid (J) containing the remaining sedimentary suspended solids and a secondary supernatant (E); and the secondary supernatant (E) A distribution mechanism (85, 86) that distributes water to the first to third distribution channels (81 to 83), a water tank that is disposed downstream of the second distribution channel (82), and that includes activated sludge for treating ammonia and the like; Membrane separation activated sludge treatment equipment (MBR: membrane bioreactor) consisting of filtration membranes for separating suspended suspended solids and bacteria from activated sludge treated water ) (5) and a membrane filtration device (6) which is arranged downstream of the third branch channel (83) and which comprises a filtration membrane for separating suspended suspended matter and bacteria from the secondary supernatant (E) An adjustment tank (7) that is disposed downstream of the membrane separation activated sludge treatment device (5) and the membrane filtration device (6) and stores treated water that has been subjected to purification treatment, and the first branch channel (81). Refrigerated water supply port (81A) that returns the secondary supernatant (E) into the rearing water tank (1) and the treated water in the adjustment tank (7) into the rearing water tank (1). A reflux path (84) and an untreated water storage tank (4) that is disposed upstream of the membrane separation activated sludge treatment device (5) and stores the secondary supernatant, the primary supernatant, or the waste water. A method of raising seafood characterized by The breeding method according to claim 1, wherein the amount of particulate activated carbon added is 0.2 to 5.0 wt% in dry weight with respect to the treated water containing activated sludge in the aeration tank. Method. The breeding method according to claim 1, wherein the amount of particulate activated carbon added is 0.4 to 2.5% by dry weight with respect to the treated water containing activated sludge in the aeration tank. Method. The breeding method according to claim 2, wherein the amount of particulate activated carbon added is 0.2 to 5.0 wt% in dry weight with respect to the treated water containing activated sludge in the aeration tank. Method. The breeding method according to claim 2, wherein the amount of particulate activated carbon added is 0.4 to 2.5% by weight in dry weight with respect to the treated water containing activated sludge in the aeration tank. Method. The breeding method according to claim 3, wherein the addition amount of the particulate activated carbon is 0.2 to 5.0 wt% in dry weight with respect to the treated water containing activated sludge in the aeration tank. Method. The breeding method according to claim 3, wherein the amount of particulate activated carbon added is 0.4 to 2.5% by dry weight with respect to the treated water containing activated sludge in the aeration tank. Method. 2. The method for breeding fish and shellfish according to claim 1, wherein the activated carbon is powdered activated carbon or granular activated carbon in which the particle size of the particulate activated carbon is 20 mesh or less. 3. The method for breeding fish and shellfish according to claim 2, wherein the activated carbon is powdered activated carbon or granular activated carbon in which the particle size of the particulate activated carbon is 20 mesh or less. 4. The method for breeding fish and shellfish according to claim 3, wherein the activated carbon is powdered activated carbon or granular activated carbon in which the particle size of the particulate activated carbon is 20 mesh or less.   Suspended and excreted substances are separated or decomposed from rearing water, including residual food, feces, and ammonia and organic excretions excreted by the reared fish extracted from the rearing tank of the closed-circulation aquaculture equipment that rears seafood When raising cultured fish using a closed-circulation aquaculture device equipped with a membrane separation activated sludge treatment device as a treatment device, a powder having a particle size of 20 mesh or less in the aeration tank of the membrane separation activated sludge treatment device A method for breeding seafood, characterized in that activated carbon or granular activated carbon is operated by adding 0.2 to 5.0% by weight in dry weight to treated water containing activated sludge in an aeration tank.   14. The breeding method according to claim 13, wherein the closed-circulation aquaculture device comprises at least a breeding tank (1) for breeding fish and shellfish, and residual food or feces drawn from the lower end of the breeding tank (1). A storage tank (2) that temporarily stores wastewater containing a lot of suspended solids, a membrane-separated activated sludge treatment device (3) that purifies untreated breeding water drawn from a storage tank located downstream of the storage tank, and its downstream An adjustment tank (4) that has a temperature adjustment function for storing treated water that has been subjected to purification treatment, and oxygen infusion that adjusts the dissolved oxygen concentration of the treated water fed from the adjustment tank and supplied to the breeding tank A method for raising seafood, characterized by comprising a device (5).   14. The breeding method according to claim 13, wherein the closed-circulation aquaculture apparatus is configured to suspend the aquatic tank (1) for cultivating seafood and the drainage (B) drawn from the lower end of the aquarium (1). A first suspended substance separation device (2) for separating the substance-containing liquid (M) and the primary supernatant (C), the breeding water (A) drawn from the upper part of the breeding tank (1), and the above 1 A second suspended material separator (3) for separating the second supernatant (C) into a liquid (J) containing the remaining sedimentary suspended solids (J) and a second supernatant (E); and the second supernatant (E) A distribution mechanism (85, 86) that distributes water to the first to third distribution channels (81 to 83), a water tank that is disposed downstream of the second distribution channel (82), and that includes activated sludge for treating ammonia and the like; Membrane-separated activated sludge treatment device (5) consisting of a filtration membrane for separating suspended suspended solids and bacteria from activated sludge-treated water, and below the third branch channel (83) A membrane filtration device (6) comprising a filtration membrane for separating suspended suspended matter and bacteria from the secondary supernatant (E), a membrane separation activated sludge treatment device (5), and a membrane filtration device ( 6) an adjustment tank (7) that is disposed downstream of the purified water to be treated, and the secondary supernatant forms the downstream end of the first diversion channel (81) into the breeding water tank (1). (E) Return water feed port (81A), treated water return channel (84) for returning treated water in the adjustment tank (7) to the breeding tank (1), and membrane separation activated sludge treatment device (5) A seafood rearing method comprising the secondary supernatant, the primary supernatant, or an untreated water storage tank (4) for storing the waste water.

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