JP2015192627A - Closed type culture system and culture water purification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a closed type culture system capable of reducing running cost by reducing used amount of water quality regulator (ORP regulator) and extending a use period of active carbon; and a purification method of culture water.SOLUTION: The closed type culture system 1 has a culture water tank 2 for culturing fish and shellfish and an ozone treatment part 4 for decomposing and removing ammonia contained in culture water 3 extracted from the culture water tank 2. The closed type culture system 1 includes an active carbon treatment part 5 which reduces oxidation-reduction potential (ORP) of the culture water 3 increased by the ozone treatment through treatment with active carbon.

Description

  The present invention relates to a closed-type aquaculture system that purifies and cultivates fishery products while circulating aquaculture water.

  In aquaculture farms, farms and aquarium aquaculture, excrements and residual food from fish and shellfish are decomposed by microorganisms in the water, and ammonia nitrogen (hereinafter simply referred to as “ammonia”) accumulates in the water. Go. Since this ammonia is highly biologically toxic, it causes serious respiratory disturbances in fish and shellfish. Therefore, in the case of long-term breeding or high-density aquaculture, ammonia easily accumulates in the aquaculture water, which is a big problem.

  The simplest method for removing ammonia in the aquaculture water is to pour fresh seawater into the aquaculture tank and exchange the fresh seawater with the aquaculture water containing ammonia. However, the drainage has many problems in that the environmental load is high and the cost for water replacement is necessary. If the aquaculture water is recycled, these problems do not occur. In that case, the ammonia contained in the aquaculture water must be decomposed and removed in the aquaculture facility.

  Conventionally, in water tanks that are used while circulating aquaculture water, a biological treatment method has been performed in which ammonia is removed by biodegradation using microorganisms. The biological treatment method is a method using the metabolism of microorganisms, and is the most frequently used method because it does not cause any harm to fish and shellfish and does not require advanced facilities and operation techniques. In this method, after changing ammonia into nitrous acid and nitric acid by an aerobic ammonia nitrifying bacterium, nitric acid is changed into nitrous acid and nitrogen by an anaerobic denitrifying bacterium and released into the air. .

  However, this biological treatment method requires a very long period of several weeks to several months to propagate ammonia nitrifying bacteria that can sufficiently decompose ammonia in water. It is easy, and when the water temperature is low, the activity of ammonia nitrifying bacteria is significantly reduced, so that detailed operation management according to the state of the load is necessary to maintain an environment in which organisms can act appropriately, denitrification treatment Is performed in an oxygen-free state, the aeration pump that prevents oxygen-free aquaculture water from being sent to the aquaculture tank is a large and expensive process, and the flow rate drop due to clogging of the treatment tank is eliminated. Therefore, there is a problem that it is necessary to periodically clean the biological treatment tank.

In recent years, a method using ozone has been proposed as a method for efficiently decomposing and removing ammonia in aquaculture water without these problems. When ozone is injected into seawater or brackish water composed of seawater and fresh water (hereinafter simply referred to as “seawater”) and dissolved, bromide ions present in the seawater are oxidized by ozone and hypobromite ions ( This produces oxidants such as BrO ⁻ ) and bromate ions (BrO ₃ ⁻ ). Hypobromite ions (BrO-) generated by ozone dissolution react with ammonia, and ammonia is directly converted into nitrogen gas and discharged into the air, so that ammonia in the aquaculture water can be removed. This method is a simple method because bromine ions present in seawater can be used as they are.

  In addition, ozone and oxidants such as hypobromite ions and bromate ions have a strong bactericidal power and can kill almost all pathogenic microorganisms such as bacteria, viruses and parasites. Removal and breeding can be prevented. However, ozone and oxidants have a bactericidal effect, but they are toxic to humans and seafood, so it is necessary to prevent residual ozone from remaining in the aquacultured water and to remove the generated oxidants. There is.

  By measuring the oxidation-reduction potential (hereinafter simply referred to as “ORP”) of the water to be treated, which is related to the amount of ozone injected, it is possible to grasp the decomposition status of ammonia in the water to be treated by ozone and It is known that residual ozone can be prevented from being generated in the water to be treated by controlling the amount.

  In addition, a technique for removing oxidants (oxidative products) generated by ozone treatment of ammonia in aquaculture water has been proposed.

  In Patent Document 1, in order to almost completely decompose ammonia, an oxidation-reduction potential measuring electrode for measuring ORP of ozone-treated seawater is provided near the exit of the ozone contact tower, and the ORP falls within the range of 450 to 650 mV. In order to bring the concentration of ammonia close to zero, the ORP of the ozone-treated seawater is in the range of 550 to 650 mV. It is described that it is preferable to control the ozone injection amount.

  In Patent Document 2, the cultured water is first purified and disinfected by ozone treatment, then the residual oxidizing product is removed by a small amount of activated carbon treatment, and then the residual oxidizing substances are removed by returning to the cultivation water tank. A rearing device that can be used is disclosed.

Japanese Patent Laid-Open No. 5-64533 JP-A-3-21820

  However, in the breeding facility described in Patent Document 1, the amount of ozone injection is controlled so that the ORP of the aquaculture water is kept in the range of 450 to 600 mV. In general, the amount of ammonia generated in the aquaculture water by seafood is Since it varies greatly depending on the aquaculture environment and varies depending on the quality of the aquaculture water to be treated, a variety of aquaculture can be achieved simply by controlling the ozone injection amount so that the ORP of the aquaculture water is kept in the range of 450 to 600 mV. Ammonia cannot be effectively decomposed and removed in accordance with the environment and water quality.

  The decomposition and removal of ammonia by ozone is performed at a stage where the ORP of the culture water is in the range of 450 mV to 550 mV, but the OPR of the culture water after decomposing and removing ammonia is about 800 mV. The underwater ORP suitable for the survival of seafood varies depending on the type of seafood. It is 350-400 mV for saltwater fish, 200-260 mV for freshwater fish, 350-400 mV for invertebrates, and the average value of the natural sea is around 350 mV. Although it is widely known, the aquaculture water after the ozone treatment has an ORP of about 800 mV, and is not suitable for the survival of seafood.

  In the breeding apparatus described in Patent Document 2, most of the remaining oxidant (oxidative product) generated and remained in the culture water by ozone injection can be removed by performing activated carbon treatment. Although it is described that the pollutant component can be removed and the pH value of the aquaculture water after the activated carbon treatment is adjusted to a predetermined value, there is no mention of the ORP of the aquaculture water raised by the ozone treatment. Absent. As described above, since the OPR of the aquaculture water after removing ammonia is about 800 mV, the aquaculture water obtained by decomposing and removing ammonia by this breeding apparatus is not suitable for aquaculture.

  Moreover, about the raise of ORP of the culture water after ozone treatment, it can respond by adding an ORP regulator to the culture water after ozone treatment. Suitable ORP regulators include, for example, vitamin C and its derivatives, vitamin P and its derivatives, amino acids, polyphenols, flavonoids, catechins, dicarboxylic acids, gallic acid, citric acid and other hydroxy acids and their derivatives, or mixtures thereof ing. These antioxidants are water-soluble and are not industrial reducing agents for which toxicity is a concern, so there is no adverse effect on fish and shellfish. However, in order to cope with the increase in ORP of the aquaculture water after the ozone treatment, the addition of the ORP regulator is a factor that increases the running cost of the aquaculture.

  The present inventors have conducted various experiments and studies in order to solve these problems and put a method of decomposing ammonia contained in aquaculture water with ozone into practical use. As a result, it was found that not only residual oxidants can be removed by treating activated water of the cultured water after the ozone treatment, but also the ORP of the cultured water increased by the ozone treatment can be greatly reduced. . That is, in the ozone treatment of the aquaculture water, the aquaculture water ORP rises as the ammonia in the aquaculture water is decomposed and removed, and becomes a value that is not suitable for fishery products. The reduced ORP can be lowered. In particular, while activated charcoal is functioning sufficiently, the present inventors have found that the ORP of cultured water after ozone treatment can be lowered to a level that does not cause any problems in the presence of seafood by simply treating the activated carbon.

  In addition to this, it was confirmed that the pH value of the aquaculture water before ozone treatment with ozone greatly affects the amount of bromic acid generated during the ozone treatment. That is, the present inventors have found that the amount of bromic acid generated after ozone treatment is suppressed when the pH of the aquaculture water before ozone treatment is within a predetermined range.

  The present invention has been developed to solve the above-mentioned problems based on these findings. The object of the present invention is to reduce the amount of water quality regulator (ORP regulator) used and to reduce the amount of activated carbon. An object of the present invention is to provide a closed-type aquaculture system and a method for purifying aquaculture water that can reduce running costs by extending the period of use.

  In order to achieve the above object, the invention according to claim 1 is a closed-type aquaculture having an aquaculture tank for culturing seafood and an ozone treatment unit for decomposing and removing ammonia contained in the aquaculture water extracted from the aquaculture tank. The system includes an activated carbon treatment unit that reduces the redox potential (ORP) of the cultured water that has been raised by the ozone treatment by treating the cultured water extracted from the aquaculture tank with ozone and then treating with activated carbon. This is a closed-type aquaculture system.

  The invention which concerns on Claim 2 is a closed type aquaculture system provided with the ORP meter which measures the oxidation reduction potential (ORP) of the said culture water before the culture tank after the said activated carbon treatment part.

  The invention which concerns on Claim 3 is a closed type aquaculture system provided with the ORP meter which measures the oxidation reduction potential (ORP) of the said culture water immediately after the said ozone treatment part.

  The invention which concerns on Claim 4 measures the water quality of the said aquaculture water which the ozone treatment was complete | finished, and after adjusting water quality so that the quality of the said aquaculture water may become an tolerance | permissible range, the water quality adjustment part made to return to the said aquaculture tank is provided. It is a closed aquaculture system.

  The invention which concerns on Claim 5 is a closed type aquaculture system which has the aquaculture tank which cultures seafood, and the ozone treatment part which decomposes | disassembles and removes the ammonia contained in the aquaculture water extracted from the aquaculture tank. A method for purifying aquaculture water comprising the step of reducing the oxidation-reduction potential (ORP) of the aquaculture water increased by the ozone treatment by decomposing and removing ammonia contained by the ozone treatment and then treating with activated carbon. is there.

  The invention which concerns on Claim 6 is the purification method of culture water which has the process of lowering | hanging the pH of the said culture water prior to the said ozone treatment of culture water.

  According to the invention according to claim 1, since the ORP of the aquaculture water that has been raised by decomposing and removing ammonia by the ozone treatment can be greatly reduced to a level at which fish and shellfish can be grown only by the activated carbon treatment, The amount of the ORP regulator added to adjust the quality of the aquaculture water after the treatment can be greatly reduced, and the running cost required for the operation of the closed aquaculture system can be reduced.

  According to the invention which concerns on Claim 2, since it has the ORP meter which measures the oxidation reduction potential (ORP) of culture water after returning to an aquaculture tank after activated carbon treatment, first, ORP of culture water after activated carbon treatment is Whether it is low enough to return to the aquaculture tank can be judged. When the ORP value measured by this ORP meter is too high, the ORP value can be adjusted by adding an ORP adjusting agent or the like before returning to the aquaculture tank. In addition, by providing such an ORP meter, it is possible to determine whether or not the processing ability of activated carbon is sufficiently maintained. The activity of activated carbon decreases as the cultured water after the ozone treatment is processed. However, when the activity of the activated carbon decreases, the degree of decrease in the ORP value of the cultured water due to the activated carbon treatment tends to decrease. Therefore, by measuring the ORP value of the aquaculture water after the activated carbon treatment, it is possible to grasp the decline in the treatment capacity of the activated carbon, and it is possible to appropriately determine the time for maintenance or replacement of the activated carbon.

  According to the invention which concerns on Claim 3, since the ORP meter which measures the oxidation-reduction potential (ORP) of culture water is provided immediately after an ozone treatment part, the change of ORP of culture water by ozone treatment is detected sharply. Since it is possible to grasp the decomposition state of ammonia contained in the aquaculture water, it is possible to accurately grasp the time point when the decomposition and removal of ammonia is completed, and to end the ozone treatment, thereby preventing unnecessary ozone treatment.

  According to the invention of claim 4, since the quality of the aquaculture water after the ozone treatment is adjusted to be within an acceptable range and then returned to the aquaculture tank, the water quality can be maintained in a good state in the aquaculture tank. it can.

  According to the invention according to claim 5, since the ORP of the cultured water that has been raised by the ozone treatment can be greatly reduced to a level at which fish and shellfish can be grown simply by the activated carbon treatment, the quality of the cultured water after the ozone treatment can be reduced. It is possible to greatly reduce the amount of ORP regulator added for adjustment.

  According to the invention which concerns on Claim 6, since the generation amount of bromic acid by ozone treatment can be suppressed by lowering the pH of the culture water prior to the ozone treatment, bromic acid contained in the culture water after ozone treatment can be reduced. The use period of the activated carbon for removal can be extended, and the consumption can be reduced.

It is a schematic diagram which shows one Example of the closed type aquaculture system in this invention. It is a schematic diagram which shows the other Example of the closed type aquaculture system in this invention. It is a schematic diagram which shows the further another Example of the closed type aquaculture system in this invention. It is a schematic diagram which shows the test apparatus which confirms the effect of activated carbon treatment. It is a test result which shows that ORP of culture water falls by activated carbon treatment. It is a test result which shows that pH of culture water rises by activated carbon treatment. It is a schematic diagram which shows the test apparatus which confirms the influence which the difference in pH of culture water has on an ozone treatment result. It is a test result which shows the ozone treatment condition of ammonia by the difference in pH of culture water. It is a test result which shows that the generation amount of the bromic acid produced by ozone treatment changes with the difference in pH of culture water. It is a schematic diagram which shows the test apparatus which confirms the relationship between the capability fall of activated carbon, and ORP.

Hereinafter, embodiments of a closed-type aquaculture system and a culture water purification method according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of the closed type aquaculture system of the present invention. The closed-type aquaculture system 1 includes an aquaculture tank 2 for culturing seafood, an ozone treatment section 4 for ozone treatment of the aquaculture water 3 extracted from the culture tank 2, and an activated carbon treatment section for activated carbon treatment of the culture water 3 after the ozone treatment. 5, water quality adjustment tank 6 that measures the water quality of cultured water 3 that has been treated with activated carbon, adjusts the water quality as needed, and returns to the culture water tank, pipe 14 that connects these, and pipe 14 The water pump 15 and a control unit (not shown) are included.

  The aquaculture tank 2 and the ozone treatment unit 4 are connected by a pipeline 14a, and a water pump 15a is provided in the middle of the pipeline 14a. The ozone treatment unit 4 and the water quality adjustment tank 6 are connected by a pipeline 14b, and a water pump 15b and the activated carbon treatment unit 5 are provided in the middle of the pipeline 14b. A pipe 14c is provided between the water quality adjusting unit 6 and the aquaculture tank 2, and a water supply pump 15c is provided in the middle of the pipe 14c. With such a configuration, a part of the aquaculture water 3 can be taken out from the aquaculture tank 2, purified, and returned to the aquaculture tank 2.

  The aquaculture tank 2 is an aquarium that stores aquaculture water 3 (seawater) and cultures seafood, and a pipe 14a that connects the aquaculture tank 2 and the ozone treatment unit 4 is connected to the bottom of the aquarium. A water supply pump 15 a whose operation is controlled by the control unit is provided in the middle of the pipe line 14 a, and a part of the aquaculture water 3 stored in the aquaculture tank 2 is taken out and supplied to the ozone treatment unit 4. Can do. The aquaculture tank 2 is provided with an ORP meter 11a for measuring the ORP of the aquaculture water 3, a pH meter 12a for measuring the pH, and a water temperature meter 13 for measuring the water temperature. These measurement data are sent to the control unit. It is done. In this example, the aquaculture tank 2 having an internal capacity of 2 tons was used.

  The ozone treatment unit 4 generates an ozone treatment tank 7 for storing the aquaculture water extracted from the aquaculture tank 2, a diffusion tower 8 for aeration injection of ozone into the aquaculture water, and ozone supplied to the diffusion tower 8 The ozone generation part 9 is made to irradiate the aquaculture water into which the ozone has been injected with ultraviolet rays to decompose the ozone remaining in the aquaculture water. In addition, the ozone treatment tank 7, the air diffusion tower 8, the UV reaction tank 10, and the ozone treatment tank 7 are connected by a pipeline 14d that circulates them, and a water pump 15d is provided in the middle of the pipeline 14d. It has been.

  Inside the ozone treatment tank 7, an ORP meter 11b for measuring the ORP of the stored aquaculture water and a pH meter 12b for measuring the pH are provided, and these measurement data are sent to the control unit. In this embodiment, the ozone treatment tank 7 having an internal capacity of 0.5 tons was used.

  The air diffusion tower 8 diffuses and injects the ozone supplied from the ozone generator 9 into the aquaculture water fed from the ozone treatment tank 7 by the water pump 15d, reacts the ammonia in the aquaculture water with ozone, and decomposes and removes the ammonia. To do.

  The ozone generator 9 separates nitrogen from air, which is a raw material gas, by an oxygen concentrator (PSA: Pressure Swing Adsorption) to generate oxygen gas having a purity of 90% or more, and this oxygen gas is ozone-generated by a silent discharge method with an ozonizer. Into the diffuser tower 8.

  In the UV reaction tank 10, the culture water is irradiated with ultraviolet rays by a UV lamp for sterilization to kill germs and viruses contained in the culture water and decompose residual ozone remaining in the culture water without reacting with ammonia. .

  In addition, an ORP meter 11d is provided in the pipe line 14d immediately after the UV reaction tank 10, and the ORP of the aquaculture water immediately after the ozone treatment is measured. By providing the ORP meter 11c immediately after the UV reaction tank 10, the change in the ORP of the aquaculture water due to the ozone treatment can be detected sensitively, and the ozone treatment can be quickly controlled based on the ORP.

  The activated carbon treatment unit 5 is a container containing activated carbon, and by passing the culture water after ozone treatment, the activated water contained in the culture water is filtered and removed by activated carbon, and the culture water increased by the ozone treatment Activated carbon treatment is performed to reduce the ORP. In this example, activated carbon was filled in a cylindrical container having an internal capacity of 60 liters in an amount of about 13.5 kg (packing density 0.49 g / ml) to constitute the activated carbon treatment unit 5. Moreover, the raw material of this activated carbon is coconut husk, and used the above thing of loss on drying 0.8%, pH5.9, iodine adsorption performance 1120mg / g, particle size 4.75-2.63mm, or more.

  The water quality adjustment tank 6 is a container for storing aquaculture water that has been subjected to ozone treatment and activated carbon treatment, and includes an ORP meter 11c and a pH meter 12b. The measurement data of the ORP meter 11c and the pH meter 12b is sent to the control unit, and it is determined whether or not the quality of the aquaculture water that has been subjected to the ozone treatment and the activated carbon treatment is within an allowable range. In addition, the water quality adjusting tank 6 is provided with a metering pump (not shown), and a water quality adjusting agent (sodium hydroxide (NaOH), hydrochloric acid (Hcl), ascorbic acid, etc.) is added to the aquaculture water, followed by ozone treatment and activated carbon treatment. The water quality can be adjusted so that the quality of the aquaculture water that has been completed is adjusted to a water quality that enables the cultivation of seafood in the aquaculture tank 2. In this embodiment, the water quality adjustment tank 6 has the same internal capacity as the ozone treatment tank 7 of 0.5 tons.

The operation of the closed type aquaculture system 1 configured as described above will be described in detail below.
When the concentration (g / L) of ammonia contained in the aquaculture water in the aquaculture tank 2 is measured by an appropriate method, and this concentration exceeds a value that is thought to affect the growth and life and death of seafood It is determined that the ammonia concentration is excessive, and the purification process is started.

  First, a control part takes out a part (300L) of the aquaculture water 3 from the bottom part of the aquaculture water tank 2 via the pipe line 14a, and transfers it to the ozone treatment tank 7 of the ozone treatment part 4 with the pump 15a. Since the internal volume of the ozone treatment tank 7 is 0.5 ton, the entire amount of the aquaculture water (300 L) taken out from the aquaculture tank 2 can be stored. In addition, the arrow in a figure shows the direction through which culture water flows.

  When the storage of the aquaculture water in the ozone treatment tank 7 is completed, the control unit stops the operation of the water pump 15a and starts the operation of the water pump 15d, the ozone generation unit 9, and the UV reaction tank 10. When the water pump 15d is activated, the culture water in the ozone treatment tank 7 flows through the pipe line 14d and the direction indicated by the arrow 17 between the ozone treatment tank 7, the air diffusion tower 8, the UV reaction tank 10, and the ozone treatment tank 7. It circulates to. At this time, in the ozone diffuser tower 8, ozone supplied from the ozone generator 9 is diffused and injected into the culture water, and the ozone decomposes ammonia contained in the culture water.

  In the UV reaction tank 10 next to the air diffusion tower 8, the germs and viruses contained in the culture water are killed by the ultraviolet rays emitted from the UV lamp for sterilization, and the residue remaining in the culture water without being used for decomposing ammonia. Decomposes ozone. Thereafter, the aquaculture water returns to the ozone treatment tank 7 after the ORP immediately after the ozone treatment is measured by the ORP meter 11d.

  Since the aquaculture water stored in the ozone treatment tank 7 is gradually decomposed and removed while circulating in the ozone treatment section 4, the diffuser tower 8 and the UV reaction tank are used until the ozone treatment is completed. Even immediately after passing through 10, ammonia still remains in the aquaculture water. Since the ORP of the aquaculture water from which the ammonia has been decomposed and removed is different from the ORP of the aquaculture water remaining without being decomposed, the ORP meter 11d measures the ORP of the aquaculture water immediately after the ozone treatment. It is possible to detect the change of the ORP sensitively and control the ozone treatment appropriately and quickly.

  The circulating water diffuser tower 8, the UV reaction tank 10, and the ozone treatment tank 7 stored in the ozone treatment tank 7 are circulated through an ORP meter 11 d installed immediately after the UV transfer tank 10 in the pipe line 14 d. This measurement value is continued until it becomes a value at which it can be determined that ammonia has been sufficiently decomposed and removed. In the decomposition of ammonia by ozone, harmful oxidants (such as bromic acid) may be generated if the reaction proceeds excessively. Therefore, in the present embodiment, the state in which ammonia has been sufficiently decomposed and removed is a state in which a large amount of ammonia has been decomposed and removed, but the ammonia remains to the extent that no harmful components due to excessive reaction occur. means. When the measured value of the ORP meter 11d reaches a value at which it can be determined that the ammonia has been sufficiently decomposed and removed, the control unit stops the operation of the water pump 15d, the ozone generation unit 8, and the UV reaction tank 10, and the ozone treatment tank Then, the ORP meter 11b measures the ORP of the aquaculture water stored therein, reconfirms the decomposition and removal of ammonia, and then terminates the processing in the ozone processing unit 4.

  Next, the control unit starts the operation of the water pump 15b, and the aquaculture water from which ammonia is decomposed and removed by the ozone treatment stored in the ozone treatment tank 7 is passed through the activated carbon treatment unit 5 through the conduit 14b. Transfer to the water quality adjustment tank 6. At this time, the flow rate of the aquaculture water flowing through the pipeline 14b is adjusted so that the SV value described later becomes 15. (The flow rate of the aquaculture water in this example is 30 L / min)

  The aquaculture water that has passed through the activated carbon of the activated carbon treatment unit 5 provided in the middle of the pipe line 14b is filtered to remove residual oxidant generated during the ozone treatment in the ozone treatment unit 4, and the pH rises. Will decline. In particular, while the activated carbon is functioning sufficiently, the ORP of the aquaculture water that has risen to the extent that seafood cannot be inhabited by ozone treatment simply by passing the activated carbon to a level where there is no problem in the habitat of seafood. Can be reduced.

  While the oxidant is filtered and removed by the activated carbon treatment unit 5, the aquaculture water in which the ORP is lowered is stored in the water quality adjusting tank 6. Since the internal volume of this water quality adjustment tank 6 is 0.5 ton which is the same as the internal volume of the ozone treatment tank 7, all the culture water (300L) transferred from the ozone treatment tank 6 can be stored. When the total amount of the aquaculture water is stored in the water quality adjustment tank 6, the ORP meter 11c and the pH meter 12b provided in the water quality adjustment tank 6 measure the ORP and pH of the culture water and send the data to the control unit.

  Based on the data from the ORP meter 11c and the pH meter 12b, the control unit has the water quality (ORP, pH) of the aquaculture water stored in the water quality adjusting tank 7 after the ozone treatment and the activated carbon treatment are within an allowable range. It is determined whether or not there is. For example, it is determined whether or not the water quality of the aquaculture tank is not greatly changed compared to the water quality of the aquaculture tank 2. If the water quality is within the allowable range, the control unit operates the water supply pump 15c to return the entire amount of the aquaculture water in the water quality adjustment tank 6 to the aquaculture tank 2 through the conduit 14c. If the water quality is not within the allowable range, the control unit adds a water quality adjusting agent to the aquaculture water from a metering pump (not shown), adjusts the water quality within the allowable range, and then operates the water pump 15c to adjust the water quality. The entire amount of the aquaculture water in the tank 7 is returned to the aquaculture tank 2 via the pipe line 14c.

  In the water quality adjustment tank 6, since the ORP of the aquaculture water treated with activated carbon is measured, if the ORP of the aquaculture water is not sufficiently reduced, it is determined that the activated carbon capacity of the activated carbon treatment unit 5 has been reduced. It is possible to take measures to replace it with new activated carbon.

  The closed-type aquaculture system 1 purifies the entire aquaculture water 3 in the aquaculture tank 2 by repeating the above operation until the ammonia concentration contained in the aquaculture water 3 in the aquaculture tank 2 reaches a predetermined concentration. Water quality suitable for habitat can be maintained.

  The closed-type aquaculture system 1 is characterized in that the ozone treatment process and the activated carbon treatment process performed after the ozone treatment are completely separated. That is, in the ozone treatment process performed in the ozone treatment unit 4, the aquaculture water extracted from the culture water tank 2 and stored in the ozone treatment tank 7 is ozone-treated while circulating in the ozone treatment unit 4. It is transferred to the activated carbon treatment unit 5 after confirming that the ammonia contained in the aquaculture water has been sufficiently decomposed and removed by measuring the ORP of the aquaculture water inside. The aquaculture water treated with activated carbon in the activated carbon treatment unit 5 is stored in the water quality adjustment tank 6 and then measured for the ORP and pH after the activated carbon treatment. If the water quality is within the acceptable range, it remains within the acceptable range. If not, the water quality is adjusted and then returned to the aquaculture tank 2. Thus, since it transfers to the following process, after confirming that the process was reliably performed for every important process process, the purification process of culture water can be performed reliably.

  Moreover, the ORP of the aquaculture water increased by ozone treatment can be reduced by the activated carbon treatment, and while the activated carbon is functioning sufficiently, the ORP is greatly reduced to a level where there is no problem in the habitat of seafood. Therefore, the water quality adjusting agent (ORP adjusting agent) added in the water quality adjusting tank 6 in order to reduce the ORP of the aquaculture water is usually unnecessary. In addition, when the ORP of the aquaculture water treated with activated carbon is insufficiently reduced, it indicates that the ability of the activated carbon is decreasing, so the addition of a water quality modifier (ORP regulator) or the replacement of activated carbon It can be determined that it is necessary.

Next, another embodiment will be described with reference to FIG. In addition, about the part which is common in embodiment shown in FIG. 1, the same code | symbol is used and description is abbreviate | omitted.
FIG. 2 is a schematic diagram showing another embodiment of the closed type aquaculture system of the present invention. The closed type aquaculture system 21 includes an aquaculture tank 2 for culturing seafood, an ozone treatment unit 4 for ozone treatment of the aquaculture water 3 taken out from the culture tank 2, and an activated carbon treatment unit for activated carbon treatment of the culture water 3 after the ozone treatment. 5, the quality of the aquaculture water to be returned to the aquaculture tank 2 is measured, and if necessary, the water quality adjustment unit 22 that returns the water to the aquaculture tank 2 after adjusting the water quality, a pipeline 14 connecting them, and a pipeline 14 It is comprised from the provided water pump 15 and the control part which is not shown in figure.

  In the closed type aquaculture system 21, a pipeline 14e that circulates upward from the bottom of the aquaculture tank 2 is disposed, and a water pump 15e is provided in the middle of the pipeline 14e. Further, the pipe line 14f is branched from the branch part 23 of the pipe line 14e, and the pipe line 14f is joined to the pipe line 14e at the junction part 24. The pipeline 14f is provided with the ozone treatment unit 4 and the activated carbon treatment unit 5, and the ORP meter 11e is provided immediately after the ozone treatment unit of the pipeline 14f, and the ORP meter 11f is provided immediately after the activated carbon treatment unit 5. .

  Further, a valve 25 is provided in the pipe line 14e immediately after the branch part 23, and a valve 26 is provided in the pipe line 14f immediately after the branch part 23, and the branching is performed by appropriately adjusting the opening degree of the valves 25 and 26. The flow rate of the aquaculture water flowing into the pipeline 14f via the part 23 can be adjusted.

  The water quality control unit 22 determines whether or not the quality of the aquaculture water to be returned to the aquaculture tank 2 is within an allowable range. The water quality control unit 22 includes, for example, a pH meter 12c and a metering pump (not shown), and when the pH of the aquaculture water is not within the allowable range or when the ORP meter 11f determines that the ORP is too high. The quality of the aquaculture water is adjusted within an allowable range by adding a pH adjusting agent or an ORP adjusting agent.

The operation of the closed type aquaculture system 21 configured as described above will be described in detail below.
When the concentration (g / L) of ammonia contained in the aquaculture water in the aquaculture tank 2 is measured by an appropriate method, and this concentration exceeds a value that is thought to affect the growth and life and death of seafood It is judged that the ammonia concentration is excessive, and the ozone treatment is started.

  First, the control unit operates the pump 15e to continuously take out the aquaculture water 3 from the bottom of the aquaculture tank 2 through the conduit 14e. The aquaculture water 3 flowing through the pipeline 14e is branched into a flow flowing through the pipeline 14e and a flow flowing through the pipeline 14f at the branching portion 23 of the pipeline 14e. The ratio of the flow rate through the pipe line 14e and the flow rate through the pipe line 14f can be set by appropriately adjusting the opening degree of the valves 25 and 26.

  The aquaculture water that has flowed into the pipe line 14f is subjected to ozone treatment by the ozone treatment unit 4 to decompose and remove ammonia. The ORP of the aquaculture water immediately after the ozone treatment is measured with the ORP meter 11e, and the decomposition state of ammonia is confirmed. If the decomposition of ammonia is insufficient, the opening of the valves 25 and 26 is adjusted to adjust the line 14f. The flow rate of the aquaculture water flowing into the water is reduced so that the ozone treatment unit 4 can completely decompose and remove ammonia.

  Thereafter, the aquaculture water is filtered by the activated carbon treatment unit 5 and the residual oxidant generated during the ozone treatment in the ozone treatment unit 4 is removed, and the ORP is lowered. In particular, while the activated carbon is functioning sufficiently, the ORP of the aquaculture water that has risen to the extent that seafood cannot be inhabited by ozone treatment simply by passing the activated carbon to a level where there is no problem in the habitat of seafood. Can be reduced.

  After the activated carbon treatment in the activated carbon treatment unit 5 is finished, the ORP of the aquaculture water is measured by the ORP meter 11f. Therefore, when the aquaculture water ORP is not sufficiently reduced, the flow rate of the aquaculture water to be treated is too large. Or the capacity of the activated carbon is reduced, so the flow rate to be introduced into the pipe line 14f is adjusted or replaced with new activated carbon.

  Thereafter, the aquaculture water merges with the pipeline 14e at the junction 24f in the pipeline 14f, and the culture water that has not been subjected to ozone treatment and the aquaculture water that has undergone ozone treatment are mixed and pH when flowing through the water quality control unit 22. When the pH is measured by the total 12c and the pH is not within the allowable range, or when the ORP is too high, the pH adjusting agent or the ORP adjusting agent is added by a metering pump (not shown) and then returned to the aquaculture tank 2 .

  The closed-type aquaculture system 21 purifies the entire aquaculture water 3 in the aquaculture tank 2 by continuing the above operation until the ammonia concentration contained in the aquaculture water 3 in the aquaculture tank 2 reaches a desired concentration, and fishery products. The water quality suitable for the habitat of can be maintained.

  Since this closed type aquaculture system 21 continuously takes out the aquaculture water from the aquaculture tank 2, performs ozone treatment, and recirculates it to the aquaculture tank 2. There is an advantage that changes in stored aquaculture water can be reduced and the influence on fishery products can be reduced.

Next, still another embodiment will be described with reference to FIG. In addition, about the part which is common in embodiment shown in FIG. 1, the same code | symbol is used and description is abbreviate | omitted.
FIG. 3 is a schematic view showing still another embodiment of the closed type aquaculture system of the present invention. The closed type aquaculture system 21 includes an aquaculture tank 2 for culturing seafood, an ozone treatment unit 4 for ozone treatment of the aquaculture water 3 taken out from the culture tank 2, and an activated carbon treatment unit for activated carbon treatment of the culture water 3 after the ozone treatment. 5, a pipe 14 connecting them, a water pump 15 provided in the pipe 14, and a control unit (not shown). That is, the closed-type aquaculture system 31 does not include a water quality adjustment tank that finally adjusts the quality of the aquaculture water to be returned to the aquaculture tank 2, unlike the closed-type aquaculture system 1. This is because the treatment of activated water with activated carbon used the effects of lowering the ORP of the cultured water and increasing the pH.

  In the closed-type aquaculture system 31, as in the above-described closed-type aquaculture system 1, the aquaculture tank 2 and the ozone treatment unit 4 are connected by a pipeline 14a, and a water pump 15a is provided in the middle of the pipeline 14a. It has been. In the ozone treatment unit 4, as in the closed culture system 1, the ozone treatment tank 7, the air diffusion tower 8, the UV reaction tank 10, and the ozone treatment tank 7 are connected by a pipeline 14 d that circulates them. A water pump 15d is provided in the middle of the pipeline 14d.

  On the other hand, in the ozone treatment part 7 of the closed type aquaculture system 31, a branch part 32 is provided in the pipe line 14d between the water pump 15d and the air diffusion tower 8, and the pipe line 14g is branched. Further, a valve 33 is provided between the branch portion 32 and the air diffusion tower 8.

  The pipe 14g branched from the pipe 14d is provided with a valve 34 and a valve 35, and the tip thereof extends into the aquaculture tank 2. A branch portion 36 is provided between the valve 34 and the valve 35 of the pipe line 14g, and the pipe line 14h is branched.

  A pipeline 14h branched from the pipeline 14g at the branching section 36 is connected to the ozone treatment tank 7, and an activated carbon treatment section 5 is provided between the branch section 36 and the ozone treatment tank 7, and a valve 37 is provided between the branch sections 36. Is provided.

The operation of the closed type aquaculture system 31 configured as described above will be described in detail below.
When the concentration (g / L) of ammonia contained in the aquaculture water in the aquaculture tank 2 is measured by an appropriate method, and this concentration exceeds a value that is thought to affect the growth and life and death of seafood It is judged that the ammonia concentration is excessive, and the ozone treatment is started.

  First, a control part takes out a part (300L) of the aquaculture water 3 from the bottom part of the aquaculture water tank 2 via the pipe line 14a, and transfers it to the ozone treatment tank 7 of the ozone treatment part 4 with the pump 15a. When the storage of the aquaculture water in the ozone treatment tank 7 is completed, the control unit stops the operation of the water pump 15a and adjusts the pH of the transferred aquaculture water from neutral to slightly acidic (about pH 6-7). Add agent to adjust. In addition, the pH of the aquaculture water suitable for aquaculture is normally neutral to weakly alkaline. In this embodiment, the pH of the aquaculture water 3 in the aquaculture tank 2 is around 8. Therefore, in this system, the process of lowering the pH of the aquaculture water is performed prior to the ozone treatment.

  After confirming that the pH of the aquaculture water stored in the ozone treatment tank 7 has been adjusted by the pH meter 12b, the valve 33 is set to the open position, the valves 34, 35, and 37 are set to the closed position, and then the water supply pump 15d, The operation of the ozone generator 8 and the UV reaction tank 9 is started.

  When the water pump 15d is activated, the culture water in the ozone treatment tank 7 flows through the pipeline 14d, and the direction indicated by the arrow 37 between the ozone treatment tank 7, the diffusion tower 8, the UV reaction tank 10, and the ozone treatment tank 7 is shown. It circulates to. At this time, in the ozone diffuser tower 8, ozone supplied from the ozone generator 9 is diffused and injected into the culture water, and the ozone decomposes ammonia contained in the culture water.

  This ozone treatment is continued until the measured value of the ORP meter 11d installed immediately after the UV reaction tank 10 in the pipe line 14d reaches a value at which it can be determined that ammonia has been sufficiently decomposed and removed. When the measured value of the ORP meter 11d reaches a value at which it is determined that the ammonia has been sufficiently decomposed and removed, the control unit stops the operation of the water pump 15d, the ozone generation unit 9, and the UV reaction tank 10, and the ORP of the ozone treatment tank 7 After measuring the ORP of the aquaculture water stored inside by a total 11b and reconfirming the decomposition and removal of ammonia, the process in the ozone treatment unit 4 is terminated.

  Next, the controller starts the operation of the water pump 15d after setting the valves 33 and 35 to the closed position and the valves 34 and 36 to the open position. When the water pump 15d is activated, the aquaculture water stored in the ozone treatment tank 7 flows through the pipe line 14d, flows into the pipe line 14g from the branch part 32, and flows into the pipe line 14h from the branch part 36. After passing through the part 5, the flow returning to the ozone treatment tank 7 is circulated in the direction of the arrow 38, and the activated carbon treatment is continued. At this time, the flow rate of the aquaculture water flowing from the ozone treatment tank 7 through the pipe line 14d is adjusted so that the SV value becomes 15. (The flow rate of the aquaculture water in this example is 30 L / min)

  By the activated carbon treatment in the activated carbon part 5, the ORP of the aquaculture water raised by the ozone treatment is lowered, and the pH of the aquaculture water lowered by the pH adjustment before the ozone treatment is raised. These values are measured by the ORP meter 11b and the pH meter 12b of the ozone treatment tank 7, and the activated carbon treatment is continued until the quality of the aquaculture water is suitable for the inhabiting of seafood. Moreover, since the ORP of the aquaculture water immediately after the activated carbon treatment is measured by the ORP meter 11g provided between the activated carbon treatment portion 5 and the ozone treatment tank 7 in the pipe line 14h, the activated carbon of the activated carbon treatment portion 5 is determined from the ORP reduction state. It is possible to confirm a decrease in the ability.

  Based on the data from the ORP meter 11b and the pH meter 12b, the control unit can maintain the quality of the aquaculture water (ORP, pH) stored in the water quality adjustment tank 7 after the treatment with ozone and activated carbon has been completed. It is determined whether or not there is. When the water quality reaches an allowable range, the control unit closes the valves 33 and 36 and opens the valves 34 and 35, and operates the water pump 15d to perform ozone treatment and activated carbon treatment in the ozone treatment tank 7. The finished aquaculture water is refluxed to the aquaculture tank 2 via the pipelines 14d and 14g.

  The closed-type aquaculture system 31 purifies the entire aquaculture water 3 in the aquaculture tank 2 by repeating the above operations until the ammonia concentration contained in the aquaculture water 3 in the aquaculture tank 2 is below the reference concentration, and the fishery products The water quality suitable for the habitat of can be maintained.

  Since this closed-type aquaculture system 31 has a conduit that can be circulated so that the aquaculture water after ozone treatment passes through the activated carbon treatment section a plurality of times, ORP can be sufficiently reduced by a single activated carbon treatment. Even if it is not possible, the ORP can be sufficiently reduced by performing the processing a plurality of times. In addition, even when activated carbon is deteriorated, the effect of raising the pH of the aquaculture water and lowering the ORP is finally achieved by circulating the aquaculture water and performing the activated carbon many times. Can do. Furthermore, since pH of culture water is adjusted to about 6-7 before ozone treatment, generation | occurrence | production of the bromic acid in ozone treatment can be suppressed effectively, and deterioration of the activated carbon in activated carbon treatment can be suppressed.

  In addition to this, the closed-type aquaculture system 31 also has an effect that the system can be configured by reducing the tank and the pH sensor one by one because the water quality adjustment tank 6 and the ozone treatment tank 7 are combined.

  In the above description of the embodiment of the closed type aquaculture system, the control unit has explained the situation in which each component is automatically operated. However, the measurement values of the ORP meter, the pH meter, etc. are displayed on the display device, It is of course possible to manually operate the closed aquaculture system based on the display.

  Next, a method for treating cultured water in the present invention will be described. The present inventors have conducted experiments and studies to solve the problem that the ORP of the aquaculture water rises due to the ozone treatment and becomes unsuitable for the seafood. As a result, the aquaculture water after the ozone treatment is treated with the activated carbon. Thus, it was found that not only the residual oxidant can be removed, but also the ORP of the aquaculture water increased as a result of the ozone treatment can be greatly reduced.

  In addition to this, if the relationship between the flow rate of the aquaculture water to be treated with activated carbon and the capacity of the activated carbon is within an appropriate range, the ORP of the aquaculture water that has increased as a result of ozone treatment only with the activated carbon treatment will be adjusted to a value suitable for the habitat of seafood. It was confirmed that it can be greatly reduced. That is, it is found that the ORP of the aquaculture water increased by the ozone treatment can be sufficiently reduced by providing an activated carbon treatment step in which the relationship between the flow rate of the aquaculture water to be activated and the capacity of the activated carbon is set in an appropriate range. It was. Here, in order to clarify the relationship between the flow rate of the aquaculture water treated with activated carbon and the capacity of the activated carbon, a value obtained by dividing the flow rate of the aquaculture water treated with activated carbon by the capacity of the activated carbon is defined as an SV value (flow rate / activated carbon capacity).

〔Example〕
Hereinafter, “OPR reduction and pH increase effect by activated carbon treatment, and relationship between SV value and ORP reduction in activated carbon treatment”, “Effect of pH difference in aquaculture water on generation amount of bromic acid after ozone treatment”, and “ The “determination of activated carbon capacity reduction based on ORP measurement results” will be described based on experimental results.

  First, “OPR reduction and pH increase effect by activated carbon treatment, and relationship between SV value and ORP reduction in activated carbon treatment” will be described. FIG. 4 shows a test apparatus used in an experiment for confirming the effect of lowering the OPR and raising the pH by the activated carbon treatment. The test apparatus 51 stores the test water 53 in the test water tank 52 and supplies the test water 53 to the ozone treatment part 58 constituted by the air diffusion tower 55, the ozone generation part 56, and the UV reaction tank 57 by the water supply pump 54. After the treatment, the test water tank 52 was refluxed. Further, by appropriately operating the valves 59, 60, 61, and 62, the activated carbon treatment unit 63 can treat the test water after the ozone treatment with the activated carbon. Further, the test water after the activated carbon treatment can be taken out into the bucket 64 by operating the valve 62.

  The test water 53 was set to 100 L, and the water temperature was set to 20 to 25 ° C. Further, 3.8 g of ammonium chloride (1.0 g as ammonia nitrogen) was added as an ammonia component and dissolved.

Ozone was separated from PSA by nitrogen in the ozone generator 56 to generate oxygen gas having a purity of 90% or more, converted into ozone by a silent discharge method with an ozonizer, and then supplied to the diffuser tower 55. In addition, the amount of ozone generation in this experiment is 30.0-33.0 g / m < ³ > (atmospheric release concentration).

  The SV value during the experiment was set by fixing the activated carbon capacity to 20 L and changing the flow rate of the test water. This experiment was performed for four types of SV values = 15, 30, 50, and 75. As the SV value increases, the capacity of test water to be treated in one pass increases, and the burden of activated carbon increases.

  The experiment was performed according to the following procedure. As Step 1, after setting the valve 59 to the open position and the valves 60, 61, 63 to the closed position, the water pump 54 is operated, the test water 53 is transferred to the ozone treatment unit 58, and the test water tank 52 is subjected to ozone treatment. Circulation treatment was performed for 15 minutes. Thereafter, the water pump 54 was stopped and the operation of the ozone treatment unit was stopped, the test water 53 in the test water tank 52 was collected, and ORP was measured.

  In step 2, after setting the valves 59 and 61 to the closed position and the valves 60 and 62 to the open position, the water pump 54 is operated, and the test water 53 is passed through the activated carbon treatment unit 63 for one pass and collected by the bucket 64. Water and measure ORP.

  As Step 3, the test water subjected to one pass treatment is returned to the test water tank 52, the valves 59 and 62 are set to the closed position, and the valves 60 and 61 are set to the open position. After circulating 63, it returned to the test water tank 52, and continued until the measured value of the ORP meter 65 reached 300 mV.

  The above procedure was repeated under the conditions of SV value = 15, 30, 50, 75, and the ORP and pH of the test water were measured.

  FIG. 5 shows ORP of test water before and after the activated carbon treatment, and FIG. 6 shows measurement data of pH of the test water before and after the activated carbon treatment. From FIG. 5, the ORP of the test water, which was about 600 mV before the activated carbon treatment, is 300 mV or less when the SV value = 15, 30, is approximately 300 mV when the SV value = 50, and the SV value = In the case of 75, it turns out that it falls to about 400 mV. In addition, since the capacity of the test water that passes through the activated carbon surface increases as the SV value increases, the contact time between the test water and the activated carbon decreases, and the effect of lowering the ORP decreases. Therefore, when the SV value = 75 It seems that the decrease in ORP is less.

  As described above, since the average value of the ORP in the natural sea is about 350 mV, as described above, if the SV value is up to about 50, the activated carbon treatment is performed even for the aquaculture water in which the ORP is increased by the ozone treatment. It shows that there is an effect of reducing ORP in a range suitable for the growth of seafood alone. In other words, by providing a process for activated carbon treatment of the cultured water after ozone treatment with an SV value in an appropriate range, it is possible to inhabit the seafood simply by treating the ORP of the cultured water raised by ozone treatment with activated carbon. Can be greatly reduced. Therefore, by providing a process for activated carbon treatment of the aquaculture water after ozone treatment with an SV value in an appropriate range, when the activated carbon capacity is sufficient, the use of a water quality adjusting agent in the water quality adjustment tank becomes unnecessary. Even when the capacity is lowered, the amount of water quality regulator used can be reduced.

  Moreover, although the same experiment was performed using the activated carbon from which the kind of raw material differs, the test result is substantially the same as shown in Table 1, and the remarkable difference by the kind of activated carbon raw material was not recognized.

  From FIG. 6, it can be seen that before and after the activated carbon treatment, the pH of the test water rises by about 0.1 for all the SA values tested. As is clear from the figure, not only the increase in pH was observed for all the SA values set as test conditions, but the increase in pH was substantially the same for all SV values.

  The present inventors have developed a phenomenon in which the amount of bromic acid generated after ozone treatment of ammonia differs depending on the pH of the aquaculture water, together with the phenomenon that the ORP of the aquaculture water decreases due to the activated carbon treatment and the phenomenon that the pH rises. It was confirmed. That is, the lower the pH of the aquaculture water before the ozone treatment, the smaller the amount of bromic acid generated in the ammonia ozone treatment. Therefore, prior to the ozone treatment for decomposing ammonia, by reducing the pH of the aquaculture water and providing a process, the amount of bromic acid generated in the ozone treatment is reduced and the consumption of activated carbon in the subsequent activated carbon treatment is reduced. It becomes possible to do. Hereinafter, “the influence of the pH of the aquaculture water on the amount of bromic acid generated after the ozone treatment” will be described based on the experimental results.

  FIG. 7 shows a test apparatus used in this test. The test apparatus 71 stores the test water 73 in the test water tank 72, and supplies the test water 73 to the ozone treatment part 78 constituted by the air diffusion tower 75, the ozone generation part 76, and the UV reaction tank 77 by the water supply pump 74. After the treatment, the test water tank 72 was refluxed.

  The test water 53 was set to 100 L, and the water temperature was set to 20 ° C. Further, 19.23 g of ammonium chloride (5.0 g as ammonia nitrogen) was added as an ammonia component and dissolved. Moreover, after dissolving ammonium chloride, a pH adjuster was added to the test water to prepare three types of test water having pHs of 6, 7, and 8.

Ozone was supplied to the diffuser tower 75 after supplying commercially available oxygen cylinder oxygen gas having a purity of 99% to the ozone generator 76, converted into ozone by a silent discharge method with an ozonizer. In addition, the amount of ozone generation in this experiment is 30.0-33.0 g / m < ³ > (atmospheric release concentration).

  The experiment was performed according to the following procedure. First, the water supply pump 74 was operated, the test water 73 was supplied to the ozone treatment unit 78, and the circulation treatment for returning to the test water tank 72 after ozone treatment was performed for 8 hours. Meanwhile, test water 73 was sampled from the test water tank 72 every 2 hours, and ammonia nitrogen and bromic acid contained in the test water 73 were measured.

  The above procedure was performed for three types of test water adjusted to pH 6, 7, and 8, and data was acquired for each. FIG. 8 shows a decrease state of ammonia nitrogen contained in the test water with respect to the passage of the ozone treatment time, and FIG. 9 shows an increase state of bromic acid contained in the test water with respect to the passage of the ozone treatment time.

  From FIG. 8, it can be seen that there is a difference in the ammonia decomposition rate between the case where the test water is pH 8, pH 6, and pH 7, and the lower the pH, the higher the ammonia decomposition rate tends to be. Moreover, it shows that ammonia contained in the test water can be decomposed and removed by ozone treatment regardless of the pH of the test water. Further, FIG. 9 shows that there is a difference in the amount of bromic acid generated when the test water is pH 8, pH 6, and pH 7, and the lower the pH, the smaller the amount of bromine generated.

  From the above, it can be seen that the treatment with neutrality or weak acidity (pH 6 to 7) is desirable in consideration of the ammonia decomposition ability and the amount of bromic acid generated. That is, ozone treatment after reducing the pH of the test water to this level not only increases the rate of ammonia decomposition, but also reduces the amount of bromic acid generated in ozone treatment compared to the case of treatment without adjustment. And there exists an effect which can suppress the capability fall of the activated carbon in subsequent activated carbon treatment.

  In addition, as described above, the activated carbon treatment has the effect of increasing the pH of the test water. Therefore, if the pH of the aquaculture water is lowered prior to the ozone treatment to suppress the generation of bromic acid in the ozone treatment, the ozone treatment is performed. Not only can the amount of activated carbon used in the activated carbon treatment to remove oxidants such as bromic acid later be used and the trial period can be extended, but also the pH of the aquaculture water can be raised simply by the activated carbon treatment. . Therefore, by providing a process for lowering the pH of the aquaculture water prior to the ozone treatment, the ozone treatment time can be shortened and the consumption of activated carbon in the activated carbon treatment can be reduced. The amount of water quality regulator used can be reduced.

  In addition to the above knowledge, the present inventors confirmed by the following experiment that "determination of the capability fall of activated carbon based on the measurement result of ORP" is possible.

  First, the test water was subjected to ozone treatment using an ozone treatment device 81 shown in FIG. The ozone treatment device 81 stores the test water 83 in the test water tank 82, and supplies the test water 83 to the ozone treatment unit 88 constituted by the diffusion tower 85 and the ozone generation unit 86 by the water feed pump 84 to perform the ozone treatment. After that, it was configured to return to the test water tank 82.

  The test water 83 had a water volume of 40 L and a water temperature of 20 to 25 ° C. Further, 0.2 g of ammonium chloride (0.052 g as ammonia nitrogen) was added as an ammonia component and dissolved.

  Ozone was separated from PSA by nitrogen in the ozone generation unit 86 to generate oxygen gas having a purity of 90% or more, converted into ozone by a silent discharge method with an ozonizer, and then supplied to the diffuser tower 85. In addition, the ozone generation amount in this experiment is 30.0-33.0 g / m3 (atmospheric release concentration).

  In the ozone treatment, first, the water supply pump 84 was operated, the test water 83 was supplied to the ozone treatment unit 88, and the circulation treatment for returning to the test water tank 84 after ozone treatment was performed for about 30 minutes. The test water after this treatment was collected. Next, the test water after the ozone treatment was subjected to a test of treating with activated carbon after measuring the ORP. The activated carbon treatment was performed by placing test water after ozone treatment in a container, immersing the activated carbon in the vessel, stirring, and then filtering. And ORP of the test water after activated carbon treatment was measured.

  In this test, the test was performed while changing the type of activated carbon, the amount of activated carbon used, the amount of treated water, and the time of immersion and stirring of the activated carbon in the test water. As the activated carbon, activated carbon A (new article), activated carbon B (used article), and activated carbon C (activated carbon B further treated with hypochlorous acid) were used. That is, the deterioration of the activated carbon C is most advanced.

  First, for activated carbon A, B and C, 25 g (dry weight) of activated carbon and 50 mL of test water are mixed in a water sampling bottle, and the immersion / stirring time is 1.0 min, 1.8 min, 3.5 min or 10 The test was conducted for 7 minutes. These conditions correspond to SV values = 50, 30, 15, or 5 as the time of contact with water, respectively. The ORP value of the test water before the activated carbon treatment was 528 mV for all. The obtained results are shown in Table 2.

  For activated carbon A and B, a test is performed in which 60 mL of activated carbon and 800 mL of test water are mixed in a water sampling bucket and immersed and stirred for 5 minutes (about SV = 10) or 7 minutes (about SV = 7). It was. In addition, ORP of the test water before activated carbon treatment was 513 mV. The obtained results are shown in Table 3.

  From Table 2, it can be seen that unless the activated carbon load has an equivalent SV value of 50, the degree to which the ORP of the test water decreases due to the activated carbon treatment decreases as the activated carbon deteriorates. It can be seen that the same result can be obtained by changing conditions such as the amount of activated carbon and test water. From this, it can be said that the degree to which the ORP value is reduced by the activated carbon treatment indirectly indicates the deterioration state of the activated carbon. Therefore, by measuring the ORP of the aquaculture water after the activated carbon treatment, it is possible to determine the state of decrease in the ability of the activated carbon, and it is possible to confirm the appropriate maintenance or replacement time.

  In a closed aquaculture system, if the ORP of the aquaculture water raised by the ozone treatment is returned to the aquaculture tank without sufficiently reducing it, there is a risk of killing the fish and shellfish bred in the aquaculture tank . For this reason, it is extremely important to be able to quantitatively and objectively determine the deterioration state of the activated carbon, which is a main means for reducing the ORP of the aquaculture water that has been raised by the ozone treatment.

  As described above, the closed-type aquaculture system and the method for purifying aquaculture water according to the present invention have the phenomenon that the ORP of the aquaculture water increased by the ozone treatment is greatly reduced by treating the aquaculture water after the ozone treatment with activated carbon. In the preferred case, it is based on the phenomenon that reducing the pH of the aquaculture water prior to the ozone treatment suppresses the amount of bromic acid produced by the ozone treatment, so water quality adjustment compared to conventional closed aquaculture systems As well as being able to reduce the amount of agent used (ORP adjuster, pH adjuster), it is possible to extend the use period or reduce the amount of use of the activated carbon in the activated carbon treatment section, Running cost can be reduced.

  In addition, by measuring the culture water ORP after the activated carbon treatment, it is possible to grasp the decline in the activated carbon capacity of the activated carbon treatment unit and confirm the replacement time, so it is possible to stably fish seafood. So its value is very big.

DESCRIPTION OF SYMBOLS 1 Closed-type aquaculture system 2 Aquaculture tank 3 Aquaculture water 4 Ozone treatment part 5 Activated carbon treatment part 6 Water quality adjustment tank 7 Ozone treatment tank 8 Aeration tower 11 ORP meter 12 pH meter 14 Pipe line 15 Water supply pump

Claims (6)

A closed aquaculture system having an aquaculture tank for culturing seafood, and an ozone treatment unit for decomposing and removing ammonia contained in the aquaculture water extracted from the aquaculture tank,
It comprises an activated carbon treatment unit that lowers the redox potential (ORP) of the aquaculture water that has been raised by the ozone treatment by treating the aquaculture water extracted from the aquaculture tank with ozone and then treating with activated carbon. Closed aquaculture system.   The closed-type aquaculture system according to claim 1, further comprising an ORP meter that measures an oxidation-reduction potential (ORP) of the aquaculture water after the activated carbon treatment unit and before the aquaculture tank.   The closed-type aquaculture system according to claim 1, further comprising an ORP meter that measures an oxidation-reduction potential (ORP) of the aquaculture water immediately after the ozone treatment unit.   The water quality adjustment part which measures the water quality of the said culture water which the ozone treatment was complete | finished, adjusts the water quality so that the quality of the said culture water becomes an allowable range, and is made to return to the said culture water tank is provided. 4. The closed type aquaculture system according to any one of 3 above.   In a closed-type aquaculture system having an aquaculture tank for culturing seafood and an ozone treatment unit for decomposing and removing ammonia contained in the aquaculture water extracted from the aquaculture tank, the ammonia contained in the aquaculture water is decomposed by ozone treatment. A method for purifying aquaculture water, comprising a step of reducing the oxidation-reduction potential (ORP) of the aquaculture water increased by the ozone treatment by performing an activated carbon treatment after the removal.   The method for purifying aquaculture water according to claim 5, further comprising a step of lowering the pH of the aquaculture water prior to the ozone treatment of the aquaculture water.

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