JP7738231B2 - Marine life food generator - Google Patents

Description

The present invention relates to a marine organism food production device that uses a filtration device to produce food for marine organisms such as shellfish and seaweed.

Until now, in marine areas where shellfish, seaweed, and other marine organisms live, oligotrophy has occurred due to a lack of nutrients such as nitrogen and phosphorus. This oligotrophy has led to a decrease in plankton, causing problems such as the inability of oysters, which feed on plankton, to grow sufficiently, and discoloration of seaweed, which grows by absorbing nutrients, causing problems for the aquaculture industry.

Patent Document 1 discloses a technology that uses a filtration device with an alternating layer structure of filter media/culture medium layers and void layers as a feed concentration device, and describes how plankton attached to the filter media/culture medium layers is used as feed for bivalve mollusks such as clams and mussels.

Patent Document 2 discloses a technology in which nitrogen and phosphorus components are dissolved from a fertilizer into water, suspended solids are filtered from the resulting eluate, and the filtered eluate is then supplied to seaweed such as Enteromorpha spp. and Sargassum spp.

Japanese Patent Application Laid-Open No. 2015-171353 Patent No. 6316579

Traditionally, seaweed grows by absorbing nutrients, so it can be said that it has a close relationship with oysters, which feed on phytoplankton that feed on nutrients. Therefore, there has been a desire to develop a feed production system that uses equipment that can simultaneously produce nutrients and plankton, and can feed the produced feed to seaweed and oysters separately.

Patent Document 1 discloses a technology for concentrating seawater and using the plankton attached to the filter media and culture medium layers as food. However, the inside of the filtration device used has a complex structure with alternating filter media layers and void layers, and because it is used submerged, inspection of the device is time-consuming. Furthermore, because aquatic organisms are cultivated inside the device, the device becomes larger. Furthermore, in marine areas where oligotrophy is a serious problem, there are limits to how much plankton can be concentrated using the capacity of the filtration device alone.

Patent Document 2 discloses a technology for supplying seaweed with leaching water containing nitrogen and phosphorus components leached from a fertilizer, thereby maintaining an appropriate concentration of nutrients in seawater. However, this requires the fertilizer to be prepared separately to generate the leaching water, which is costly.

The present invention was made in consideration of the above-mentioned problems, and provides a food production device for marine organisms. Seawater is pumped from a sewage discharge area into which treated sewage containing nutrients such as nitrogen and phosphorus generated in the final settling tank of a water treatment facility is discharged. The seawater is then supplied to a filtration device, and the treated liquid containing plankton and nutrients obtained after the filtration process is fed to oysters and seaweed, respectively.

This marine life feed production system uses seawater from an area of the ocean where treated sewage treated at a water treatment facility is discharged to cultivate marine life. It includes a conveying unit that takes in seawater from the sewage discharge area and supplies it to a filtration device; a filtration device that separates the seawater into suspended matter and treated liquid; a feeding unit that feeds the treated liquid to seaweed in a seaweed cultivation area; and a feeding unit that feeds suspended matter detached by a cleaning fluid supplied from a cleaning fluid supply pipe connected to the filtration device, together with the cleaning discharge liquid, to shellfish in a shellfish cultivation area. This allows food for seaweed and shellfish to be produced simultaneously using a single filtration device.

The feeding section is configured to supply suspended matter detached by backwashing the filter media layer to the shellfish cultivation area along with the cleaning wastewater, allowing suspended matter detached from the filter media layer to be efficiently fed to the shellfish cultivation area.

The filtration device is configured so that a foam separation device is installed below the seawater supply pipe connected above, and the foam obtained by foam separation of the supplied seawater is supplied to the shellfish cultivation area from the feeding section, allowing suspended matter contained in the stable foam to be fed to the shellfish cultivation area.

The feed production device of the present invention produces feed for seaweed and shellfish by filtering seawater pumped from a sewage discharge area where treated sewage from a water treatment facility is discharged. This single device can produce feed for multiple marine organisms. The generated feed is fed to the aquaculture area, not inside the filter device, so the device does not become too large. Furthermore, the filter device has a simple configuration with filter media filled inside, making maintenance easy. It can also be easily applied to existing fishing grounds, as it only requires installation in any sea area. Furthermore, because the treated liquid is seawater from an area where treated sewage containing nutrients is discharged, there is no need to prepare additional fertilizers, etc. This eliminates the need for separate fertilizers, and allows for the production of a treated liquid with the desired amount of plankton and the desired concentration of nutrients, even in oligotrophic sea areas. Furthermore, the device is configured to perform foam separation during the filtration process, which prevents clogging of the filter media by suspended solids and allows for continuous filtration over long periods of time, enabling continuous feed production.

1 is a schematic diagram of a feed production device according to the present invention. FIG. It is also a downward flow filtration device.

FIG. 1 is a schematic diagram of a feed production apparatus according to the present invention, and FIG. 2 is a downward flow type filtration apparatus according to the present invention.
As shown in Figure 1, the feed production device 1 of this embodiment includes a transport unit 3 that takes in treated liquid (seawater) from a sewage discharge area into which treated sewage treated in a water treatment facility is discharged and supplies it to a filtration device 2, the filtration device 2 that separates seawater into suspended matter and a treated liquid, a feeding unit 4A that feeds the treated liquid to seaweed in a seaweed cultivation area, and a feeding unit 4B that feeds suspended matter detached by a cleaning fluid supplied from a cleaning fluid supply pipe 5 connected to the filtration device 2 together with the cleaning wastewater to shellfish in the shellfish cultivation area. Each component will be described in detail below.

The transport unit 3 consists of a seawater pump (not shown) installed within the sewage discharge area and a seawater supply pipe 6 connected to the seawater pump at one end and the filtration device 2 at the other end, and is configured to pump up seawater within the sewage discharge area and supply it to the filtration device 2.

Treated sewage discharged into sewage discharge areas is a liquid that has undergone biological treatment after solids have been removed from wastewater containing nutrients (nitrogen, phosphorus, etc.), such as human waste, sewage, and wastewater from food production and processing. Specifically, the liquid to be treated flowing into a sewage treatment plant is separated by sedimentation in a primary sedimentation tank, and the separated supernatant liquid is biologically treated in an oxygen-supplied reaction tank, after which it is further separated by sedimentation in a final sedimentation tank. The supernatant liquid may be disinfected and then used as treated sewage.

The supernatant liquid discharged from water treatment facilities is generally discharged into oceans, etc., but the treatment methods described above cannot completely remove the nutrients contained in the treated liquid. For this reason, it can be said that sewage discharge areas into which treated sewage is discharged have relatively higher nutrient concentrations than other ocean areas. In addition, sewage discharge areas with high nutrient concentrations also see the proliferation of phytoplankton (hereinafter referred to as plankton), which feed on nutrients, resulting in high plankton concentrations.

In this embodiment, seawater is pumped from a sewage discharge area where concentrations of nutrients and plankton are high, and the pumped seawater is supplied to the filtration device 2. Note that the sewage discharge area in this embodiment is a closed body of water with little water flowing in or out of the area, and is an area where nutrients tend to accumulate.

As shown in Figure 2, the filtration device 2 is a downward flow filtration device in which a seawater supply pipe 6 is connected above the filtration tank 7, and seawater is supplied from above the filtration tank 7 and discharged from below. Inside the filtration tank 7, a filter media outflow prevention screen 8 is placed at a predetermined height from the bottom of the tank, and a filter media layer 9 of a predetermined thickness is formed above the screen.

The filter layer 9 is formed by filling it with irregularly shaped granular fiber filter media, and captures suspended matter contained in seawater supplied from above the filter layer 9. Since suspended matter in seawater includes plankton, plankton can be obtained in the filter tank 7 by filtering the seawater. Suspended matter in seawater also includes organic matter derived from the remains and feces of living organisms, but in this embodiment, the purpose is to obtain plankton, which serves as food for marine organisms (bivalves).

The filter material is not limited to fiber material; other filter materials such as resin filter material and sand may also be used. The diameter, shape, etc. may also be selected appropriately depending on the application. Depending on the conditions, the filter device 2 may also be placed on a raft or the like to make it a floating type.

A cleaning fluid supply pipe 5 is connected below the filter tank 7, allowing cleaning fluid to be supplied from below the filter tank 7 when cleaning the filter media. In this embodiment, a cleaning liquid supply pipe is used as the cleaning fluid supply pipe 5, and seawater (cleaning liquid) is supplied from below the filter tank 7 to clean the filter media, but if necessary, compressed air, agitator blades, etc. may also be used in combination to agitate and clean the filter media. Furthermore, the cleaning fluid is not limited to seawater.

Furthermore, the filtration device 2 has a foam separation device 10 installed above the filtration tank 7. The foam separation device 10 is located below the seawater supply pipe 6 connected above the filtration tank 7, and is configured to perform foam separation on the seawater supplied from the seawater supply pipe 6.

The foam separation device 10 consists of an air diffuser pipe connected at one end to an air supply source such as a blower or compressor (not shown). By driving the air supply source, fine bubbles are sprayed into the seawater from numerous nozzle holes 12 formed at the top of the air diffuser pipe. By supplying fine bubbles to the seawater, suspended matter in the seawater floats up and separates, forming stable foam on the water surface.

The stable foam is supplied to the shellfish cultivation area from the feeding section 4B, which will be described in detail later. Since this stable foam contains plankton, the recovery rate of plankton can be increased by performing foam separation. Note that the foam separation device 10 is not limited to the aeration tube type, as long as it generates fine bubbles.

The feeding section 4A is a pipe connected at one end to the bottom of the filtration tank 7 and at the other end to the seaweed cultivation area, and is configured to supply seawater (treated liquid) discharged after filtration to the seaweed cultivation area. The treated liquid supplied to the seaweed cultivation area has a high concentration of nutrients because it is seawater pumped from a sewage discharge area and filtered, where the concentration of nutrients is relatively high.

Nori grown in seaweed farming areas grows by absorbing nutrients, so supplying a treatment solution with a high concentration of nutrients promotes the growth of the nori. This allows for the production of high-quality nori that does not fade.

On the other hand, the feeding section 4B is a pipe connected at one end to the top of the filtration tank 7 and at the other end to the shellfish cultivation area, and is configured to supply the plankton contained in the stable foam and the plankton detached during cleaning of the filter media layer 9 to the shellfish cultivation area together with the cleaning wastewater. The cleaning wastewater supplied to the shellfish cultivation area has a high plankton concentration because it is made by filtering seawater pumped from a sewage discharge area where the plankton concentration is relatively high.

Oysters cultivated in shellfish farming areas grow by capturing plankton, so supplying the effluent, which has a high concentration of this plankton, promotes oyster growth.

The feed production method according to this embodiment will be described in detail below with reference to FIGS. 1 and 2.
<Discharge process>
In the discharge process, the treated sewage (supernatant) obtained after gravity settling in the final settling tank of the water treatment facility is discharged into any seawater (sewage discharge area).

<Transportation process>
In the transport process, seawater is pumped up from the sewage discharge area by driving a seawater pump installed in the sewage discharge area, and the seawater is supplied to the filtration device 2 via the seawater supply pipe 6. At this time, the valve V1 installed in the seawater supply pipe 6 and the valve V2 installed in the feeding unit 4A are open.

<Filtration process>
In the filtration process, the pumped seawater is supplied to the filtration device 2 for filtration. Seawater is supplied from the seawater supply pipe 6 into the filtration tank 7, and fine bubbles are supplied from the nozzles 12 of the foam separator 10 toward the top of the filtration tank 7, while suspended solids are captured by the filter layer 9 filled in the filtration tank 7. At this time, the valve V3 installed in the feeding section 4B is open.

The many fine bubbles ejected adsorb suspended matter mixed in the seawater supplied from above, as well as suspended matter that has naturally detached from the filter layer 9 due to the influence of water pressure, and rise to the water surface. The bubbles, which have adsorbed the suspended matter that rises one after another, then gather at the water surface, forming a stable foam on the water surface.

The stable foam formed on the water surface is supplied to the shellfish cultivation area from the feeding section 4B connected above the filtration tank 7. Because the stable foam contains plankton, which serves as food for the shellfish, it can be said that by performing foam separation during the filtration process, the food can be efficiently supplied to the shellfish.

Foam separation is performed continuously during the filtration process, but the timing for starting the supply of compressed air is determined as appropriate. The method for supplying stable foam from the feeding section 4B to the shellfish cultivation area can be selected as appropriate, for example, by maintaining a constant water level in the filtration tank 7 and discharging it by overflow during the filtration process. Depending on the conditions, the foam separation device 10 may be omitted and only the normal filtration process may be performed.

During the filtration process, plankton contained in the seawater passing through the filter layer 9 gradually accumulates on the filter layer 9. Meanwhile, the seawater that has passed through the filter layer 9 is supplied as treated liquid from the feeding unit 4A to the seaweed cultivation area. The treated liquid supplied to the seaweed cultivation area from the feeding unit 4A contains fine bubbles sprayed from the foam separation device 10, and supplying this treated liquid to the seaweed cultivation area promotes the growth of seaweed.

In this embodiment, feed is produced using a downflow filtration device, but an upflow filtration device may also be used. In this case, the liquid to be treated (seawater) is supplied from below the filtration tank 7, the treated liquid discharged from above the filtration tank 7 is supplied to the seaweed cultivation area, and plankton detached from the filter material by the cleaning liquid (seawater) supplied from above is supplied from below the filtration tank 7 to the shellfish cultivation area.

<Filter cleaning process>
In the filter media cleaning process, the filter media layer 9 packed in the filter tank 7 is cleaned. A cleaning liquid is supplied from the downstream side of the filter media layer 9, and water is passed through the filter media layer 9, and then discharged from the upstream side. This backwashing detaches the plankton captured by the filter media layer 9. The detached plankton, together with the cleaning wastewater (seawater that has passed through the filter media layer 9) discharged from upstream of the filter media layer 9, is supplied to the shellfish cultivation area via the feeding section 4B.

The filter media cleaning process is performed, for example, when the filtration pressure increases due to clogging caused by suspended matter captured in the filter media layer 9 during the filtration process, when the cumulative operating time reaches a predetermined time or a predetermined time, or when the treatment liquid no longer meets a predetermined standard. When cleaning the filter media, valves V1 and V2 are closed, and valve V4 installed in the cleaning liquid supply pipe 17 is opened.

Since seawater is used for cleaning, if a compressed air supply line is added below the cleaning fluid supply pipe 5, foam separation of the seawater supplied from the cleaning fluid supply pipe 5 will occur simultaneously with agitation and cleaning. Plankton is removed from the filter media by agitation and cleaning, and stable foam containing plankton can be supplied from the feeding section 4B to the shellfish cultivation area, allowing for efficient production of feed.

In this embodiment, seaweed and oysters are listed, but the invention can also be applied to other marine organisms that feed on nutrients and plankton.

The present invention is not limited to the embodiments described above. Modifications and variations are possible without departing from the spirit of the present invention.

This invention is a feed production device that filters seawater pumped from a sewage discharge area into which treated sewage containing nutrients is discharged, to obtain nutrients and plankton that serve as feed for seaweed and shellfish. Because a single filter can simultaneously produce feed for two or more types of marine organisms, this technology is effective for the aquaculture of all marine organisms that feed on nutrients and plankton. Furthermore, because it can be implemented using existing filter equipment, it can be easily applied to existing fishing grounds.

2 Filtration device 3 Conveying section 4A, 4B Feeding section 5 Cleaning fluid supply pipe 6 Seawater supply pipe 9 Filter layer 10 Foam separation device

Claims (3)

A marine organism feed production system that uses seawater from an area of the ocean into which treated sewage treated at a water treatment facility is discharged for the cultivation of marine organisms,
a conveying section (3) that takes in seawater from a sewage discharge area and supplies it to a filtration device (2);
a filtration device (2) for separating seawater into suspended solids and a treated liquid;
a feeding unit (4A) that feeds the treated liquid to seaweed in the seaweed cultivation area;
A feeding unit (4B) that feeds suspended matter detached by a cleaning fluid supplied from a cleaning fluid supply pipe (5) connected to the filtration device (2) to shellfish in a shellfish cultivation area together with the cleaning wastewater. The marine organism food production device according to claim 1, characterized in that the feeding section (4B) is configured to supply suspended matter detached by backwashing of the filter layer (9) together with the washing effluent to the shellfish cultivation area. The marine organism feed production device described in claim 2, characterized in that the filtration device (2) is configured such that a foam separation device (10) is installed below the seawater supply pipe (6) connected above, and the foam obtained by foam separation of the supplied seawater is supplied to the shellfish cultivation area from the feeding section (4B).