Concentric reactor for processing waste from land-based aquaculture systems

Abstract

End-of-pipe treatment does not enable significant water savings or reuse. [Solution] A system for removing compounds from a liquid, comprising: a plurality of ring-shaped channels that allow liquid to flow from one ring-shaped channel to another; an inlet connected to one of the ring-shaped channels that receives liquid containing compounds to be removed; a central container surrounded and connected by the plurality of ring-shaped channels; a tube connected to the central container that outputs the processed liquid from the system; a temperature device that regulates the temperature of the liquid in the plurality of ring-shaped channels; a carbon source reservoir and delivery system for supplying a carbon source to at least one of the plurality of ring-shaped channels; one or more sensors that collect information about the liquid in the plurality of ring-shaped channels; and a control device that receives information from one or more sensors and operates the carbon reservoir, temperature device and vertical lock according to the collected information.

Description

Technical Field

[0001] Field The present invention relates to the field of treating waste from an onshore aquaculture system.

Background Art

[0002] Background Recirculating aquaculture systems (RAS) are used for the onshore production of freshwater fish and seafood (e.g., fish, shrimp). In RAS, water exchange is limited and the use of biological filtration is required to reduce ammonia toxicity. [1] In many cases, other types of filtration and environmental control are also necessary to maintain clean water and provide a suitable habitat for fish. [2] The main benefit of RAS is that it can reduce the need for fresh and clean water while maintaining a healthy environment for fish.

[0003] Harmful nitrates and organic sludge often accumulate in large quantities in the environment from recirculating aquaculture systems. Furthermore, in many of these systems, geosmin and 2-methylisoborneol accumulate, which causes the fish to become unmarketable and leads to excessive water use and weight loss of the harvested fish.

[0004] Several technologies (denitrification reactors) for nitrate removal are commercially available and are mainly applied in wastewater treatment plants. Some aquaculture farmers have incorporated denitrification reactors into their farms to comply with the regulated nitrate levels in the effluent before discharge. In such systems, the denitrification reactor is not used for online treatment but is used as end-of-pipe treatment and uses an external carbon source as fuel. Sludge removal technologies in aquaculture are mainly for end-of-pipe treatment systems and are designed to mechanically concentrate and dry the sludge into a powdery by-product.

Summary of the Invention

Problems to be Solved by the Invention

[0005] End-of-pipe treatment, commonly used to remove sludge and nitrates from aquaculture effluent, does not enable significant water savings or reuse. Furthermore, its operating costs are considerably higher due to the need for an external carbon source (for denitrification) and energy-consuming sludge separation and concentration equipment. [Means for solving the problem]

[0006] Summary of the Invention This subject discloses a system for removing compounds from a liquid, the system comprising: a plurality of ring channels enabling the flow of liquid from one ring channel to another; an inlet connected to one of the ring channels for receiving liquid containing the compounds to be removed; a central container surrounded and connected by the plurality of ring channels; a tube connected to the central container and configured to discharge the processed liquid from the system; a temperature device configured to regulate the temperature of the liquid in the plurality of ring channels; a carbon source reservoir and delivery system for supplying a carbon source to at least one of the plurality of ring channels; one or more sensors configured to collect information about the liquid in the plurality of ring channels; and a control device configured to receive information from one or more sensors and to actuate the carbon reservoir, temperature device and vertical lock according to the collected information.

[0007] In some cases, the multiple ring-shaped channels are concentric. In some cases, the multiple ring-shaped channels and the central vessel include a base and side walls extending upward from the base. In some cases, the system further includes an outlet pipe connected to a tube, the outlet pipe configured to transfer the treated liquid from the central vessel to a remote tank. In some cases, the reactor is configured to operate in an aquaculture system operating at a water temperature of 10–30°C.

[0008] In some cases, the multiple ring-shaped channels include at least an outer ring surrounding an inner ring, with the inlet connected to the outer ring-shaped channel. In some cases, the outer ring includes a deflection plate positioned substantially close to the inlet, thereby regulating the direction of the liquid flow within the outer ring. In some cases, the outer ring and inner ring include one or more movable vertical locks configured to regulate the liquid flow within the ring.

[0009] This subject discloses a method for removing compounds from a liquid, the method comprising receiving a flow of wastewater into one of a plurality of ring-shaped channels, forcing the wastewater to flow in one direction along the plurality of ring-shaped channels, forming a sludge layer at the base of the plurality of ring-shaped channels, and digesting the sludge layer with fermenting bacteria in the lower part of the sludge layer.

[0010] In some cases, digestion further includes a fermentation process that results in the production of CO2 gas and volatile fatty acids (VFAs). In some cases, the method further includes the absorption of geosmin and 2-methylisoborneol into sludge particles in the sludge layer, followed by decomposition by terpene-degrading bacteria. In some cases, the method further includes maintaining the sludge within a given temperature range, detecting heating conditions of the sludge layer, and heating the sludge.

[0011] In some cases, the method further includes detecting the height of the sludge level and moving a vertical lock in response to the detection of the height of the sludge level. In some cases, one or more vertical locks move upward and downward, and the upward position of the vertical locks obstructs the passage of liquid in the ring. In some cases, the method further includes detecting carbon limiting conditions and injecting carbon into the sludge fermentation layer.

[0012] Brief explanation of the drawing Several embodiments of the present invention are described herein merely as examples with reference to the accompanying drawings. It is emphasized here, with particular detail reference to the drawings, that the illustrated details are illustrative and for explanatory purposes only, for the purpose of describing embodiments of the present invention. In this regard, by description together with the drawings, it will become clear to those skilled in the art how embodiments of the present invention can be carried out. [Brief explanation of the drawing]

[0013] [Figure 1] An exemplary embodiment of the present invention is shown, illustrating a concentric system for processing liquids in a closed environment. [Figure 2] A method for transferring liquid within a closed system, according to an exemplary embodiment of the present invention, is shown. [Figure 3] This describes a biological process that occurs in wastewater when it is transported within a closed system, according to an exemplary embodiment of the present invention. [Figure 4] A method for regulating the transfer of wastewater within a closed system, according to an exemplary embodiment of the present invention, is shown. [Modes for carrying out the invention]

[0014] A detailed description of embodiments of the present invention follows with reference to the accompanying drawings mentioned above. Dimensions of parts and features shown in the drawings have been selected for convenience or clarity and are not necessarily shown to scale. Wherever possible, the same reference numerals throughout the drawings and the following description refer to the same and similar parts.

[0015] Detailed explanation This invention discloses a concentric reactor in which effluent and sludge from fish tanks of a recirculating aquaculture system are treated to remove nitrates, sludge, and off-odor compounds, geosmin, and 2-methylisoborneol. By manipulating the water residence time, sludge level, oxidation-reduction potential (ORP), carbon / nitrogen ratio, and temperature in a compartmentalized concentric reactor, conditions are created in which the sludge is biologically digested into volatile fatty acids. These latter compounds function as carbon and energy sources, enabling the reduction of nitrates to elemental nitrogen gas by heterotrophic denitrifying bacteria. Incorporating this treatment step allows these recirculating systems to operate in a fully closed mode without the need to discharge nitrate-rich water and sludge.

[0016] The environmental conditions maintained within the reactor also enable the removal of aqueous geosmin and 2-methylisoborneol. The removal of these latter compounds is achieved through a combination of adsorption to sludge particles followed by decomposition by a specific terpene-degrading denitrifying bacterial consortium. This removal process ensures the sensory quality of farmed fish, thus eliminating the need to purge the fish before harvest.

[0017] This reactor is suitable for both marine and freshwater aquaculture systems operating at water temperatures of 10-30°C.

[0018] This invention discloses an online treatment system that enables controlled separation of sludge from aquaculture water and subsequent anaerobic digestion. Nitrates are effectively removed in the reactor by denitrifying bacteria that use their own carbon and energy sources as fuel. Aqueous off-odors in the reactor are decomposed by the native bacterial community.

[0019] Figure 1 shows a concentric system for processing liquids in a closed environment, according to an exemplary embodiment of the present invention.

[0020] This concentric system includes a plurality of ring-shaped channels that enable the flow of liquid therein. The rings surround a central container that is connected to a tube configured to output the processed liquid from the system. The central container has an output port 150 configured to be connected to an output tube that outputs the processed liquid. The rings are defined as having an elliptical, polygonal, or circular cross-sectional shape, allowing liquid to flow therethrough with minimal or no residue remaining on the sidewalls of the channels. The channels and the central container include a base and sidewalls extending upward from the base. The system may include two or more rings in addition to the central container.

[0021] Each of the plurality of ring-shaped channels and the central container has an inlet port and an outlet port. Liquid is supplied into the system at the inlet port 102 of the outer ring 100. The outer ring 100 is provided with a deflector plate 101 disposed substantially adjacent to the inlet port 102, whereby the deflector plate 101 can adjust the direction of the liquid flow within the outer ring 100. Liquid exits the outer ring 100 via an intermediate port 112 that forms a passage between the outer ring 100 and the central ring 110. Liquid exits the central ring 110 via an inner port 122 that forms a passage between the central ring 110 and the central container 120. The central container 120 has an outlet port 150 for outputting the processed liquid and returning it to the fish container.

[0022] The bases and sidewalls of the rings and the central container can be made of concrete, polypropylene, polyethylene and similar plastic-based polymers, fiberglass, glass-reinforced polymers, protruding fiberglass, galvanized steel, aluminum, and similar metal-based building materials desired by those skilled in the art.

[0023] The ring may include one or more movable vertical locks 125, 128. For example, the outer ring 100 may include the vertical lock 128, and the central ring 105 may include the vertical lock 125. The vertical locks 125, 128 regulate the flow of liquid within the ring. The vertical locks 125, 128 are movable up and down manually, by a person, or using mechanisms such as actuators, springs, pins, etc.

[0024] The system also includes an outlet pipe configured to transfer treated wastewater from the central container to a remote tank disposed outside the system. The remote tank may be a tank used to grow fish. In some cases, the outlet pipe is connected to the outlet port 150 of the central container 120.

[0025] The system also includes a temperature device 140 configured to regulate the temperature of the wastewater. The temperature device 140 may include a heat exchanger or another mechanism or device capable of heating and / or cooling the wastewater.

[0026] The system also includes a carbon source reservoir and a delivery system for supplying a carbon source to the wastewater. The carbon reservoir may be controlled by a control device that manages the processes implemented within the system.

[0027] The control device can receive signals from sensors disposed within the system, such as chemical sensors, cameras, temperature sensors, etc., and can operate modules within the system, such as the carbon reservoir 130, the temperature device 140, the vertical locks 125, 128, etc.

[0028] Figure 2 shows a method for transferring liquid within a closed system according to an exemplary embodiment of the present invention.

[0029] Step 210 discloses receiving wastewater discharged from a fish tank. The wastewater discharged may be supplied from the bottom of the tank. The wastewater discharged may contain organic solids (fish feces and leftover feed pellets). The wastewater discharged may be moved to the inlet port of the outer ring using gravity flow.

[0030] Step 220 discloses accepting a flow of wastewater through an inlet port of the outer ring. The inlet port of the outer ring is controllable and can enable and disable the discharge of wastewater into the outer ring.

[0031] Step 230 discloses forcing wastewater to flow in one direction along the outer ring. One direction may be defined as a clockwise or counterclockwise direction. Wastewater may be guided in a desired direction from the inlet port of the outer ring using an external deflection plate positioned between the inner walls of the outer ring and the intermediate ring. The deflection plate may be a wall or plate positioned close to the inlet port, extending upward from the base of the ring, and ensuring unidirectional movement of the wastewater so that the wastewater is forced in a direction opposite to the direction of the deflection plate.

[0032] Step 240 discloses that wastewater moves from the outer ring to the central ring via the intermediate port.

[0033] Step 250 discloses that wastewater moves along the intermediate ring according to the arrangement of the second deflection plate relative to the intermediate port. The flow may be clockwise or counterclockwise according to the system design.

[0034] Step 260 discloses that the treated wastewater moves from the intermediate ring to the central container via the inner port.

[0035] Figure 3 illustrates the biological processes that occur in wastewater when it is transported within a closed system, according to an exemplary embodiment of the present invention.

[0036] Step 310 discloses that wastewater flows within the system ring. This flow may be a unidirectional laminar flow defined by the base and side walls of the ring. The concentric design of the system creates suitable conditions for solids in the wastewater to settle, thus enabling the formation of a bottom sludge layer.

[0037] Step 320 discloses the formation of a sludge layer at the base of the ring. The height of the sludge layer can be limited to a specific height, for example, the maximum height from the base of the ring is 1 meter. The maximum height represents the steady-state condition for the height of the sludge layer.

[0038] Step 330 discloses the formation of an anaerobic state (i.e., absence of molecular oxygen) represented by an oxidation-reduction potential (ORP) of -400 to -200 mV. The anaerobic state is due to the formation of a sludge layer within the ring.

[0039] Step 340 discloses the development of a stable ORP-dependent bacterial population in the sludge layer.

[0040] Step 350 discloses the digestion of sludge by fermentative bacteria in the lower part of the sludge layer (fermentation layer). The fermentation process takes place at the bottom of the sludge layer. The fermentation process results in the production of CO2 gas and volatile fatty acids (VFAs). The produced CO2 moves to the upper gas layer and eventually into the atmosphere.

[0041] Step 360 discloses the consumption of VFA by denitrifying bacteria located in the upper fraction of the sludge layer (denitrification layer). The VFA consumption process results in the conversion of nitrates to elemental nitrogen gas and the oxidation of VFA to CO2 gas. Both nitrogen gas and CO2 gas move into the gas layer and ultimately into the atmosphere.

[0042] Step 370 discloses that geosmin and 2-methylisoborneol are adsorbed onto sludge particles in the devagination sludge layer and subsequently degraded by terpene-degrading bacteria.

[0043] Figure 4 shows a method for regulating the transfer of wastewater within a closed system according to an exemplary embodiment of the present invention.

[0044] Step 410 discloses maintaining the sludge within a given temperature range, for example, 25 degrees Celsius. This temperature control can be achieved using temperature sensors and heat exchangers located within the system (for example, fixed to the base and side walls of the ring and central container).

[0045] Step 420 discloses detecting heating conditions for the sludge layer. Heating conditions are defined as biological, chemical, or physical conditions that require the system to heat the sludge. Such heating conditions are when the denitrification rate of the sludge is 3 mg NO3-N / m³ 2 It may be less than / hour. Another optional heating condition is when the oxidation-reduction potential (ORP) of the sludge is higher than [-]200mV. Another optional heating condition is when the output pH level is lower than the inlet pH level.

[0046] Step 430 discloses heating the sludge. Heating can be performed in response to the detection of heating conditions. The heating process may differ depending on the heating conditions. For example, heating to 28 degrees Celsius when a first heating condition is detected, and heating to 30 degrees Celsius when a second heating condition is detected.

[0047] Step 440 discloses detecting the height of the sludge level. Detection can be performed using sensors such as image sensors, humidity sensors, temperature sensors, weight sensors, proximity sensors, laser beams, etc. These are controlled by various vertical locks.

[0048] Step 450 discloses moving a vertical lock in response to the detection of the height of the sludge level. For example, the vertical lock is normally closed. When the sludge layer reaches a height of 0.5 meters from the base of one of the rings, the vertical lock of the associated ring is released. The release may be carried out according to a set of rules. For example, the first release is at a height of 0.5 meters to 1 meter. This facilitates the movement of the sludge layer in the horizontal axis direction, and thus the sludge level in the vertical axis direction decreases. When the height of the sludge layer reaches 1 meter from the floor, the vertical lock is released to the 100% position, and the sludge layer at the base of each ring becomes further movable horizontally.

[0049] Step 460 discloses the detection of carbon limiting conditions. Carbon limiting conditions are defined as biological, chemical, or physical conditions that require the system to inject a carbon source into the sludge. Carbon limiting conditions may be detected using a chemical sensor that measures the carbon / nitrogen (C / N) ratio of the sludge, or using standard experimental apparatus. In some cases, the carbon limiting condition is when the C / N ratio of the sludge is less than 3 (COD / NO3-N(w / w)).

[0050] Step 470 discloses injecting carbon into the sludge fermentation layer. This injection may be carried out using a carbon source located near the system, for example near the outer ring, or above one of the rings or the central container, such as a tube connected to a carbon container.

[0051] The above description is merely illustrative, and various embodiments of the present invention can be devised with necessary modifications. It should be understood that features described in the above embodiments and features not described herein can be used separately or in any suitable combination; the present invention can be devised according to embodiments not necessarily described above.

[0052] While this disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various modifications are possible without departing from the scope of the invention, and that equivalents may be used instead of certain elements. Furthermore, many modifications can be made to adapt this teaching to specific situations or materials without departing from its essential scope. Accordingly, the subject matter disclosed is not intended to be limited to the specific embodiments disclosed as the best possible mode for carrying out the invention, but only to the following claims.

Claims

1. A system for removing compounds from a liquid, Multiple ring-shaped channels that allow liquid to flow from one ring-shaped channel to another, An inlet connected to one of the ring-shaped channels, which receives the liquid containing the compound to be removed, A central container surrounded and connected by the aforementioned plurality of ring-shaped channels, A tube connected to the central container, configured to output the processed liquid from the system, A temperature device configured to adjust the temperature of the liquid in the plurality of ring-shaped channels, A carbon source reservoir and delivery system for supplying a carbon source to at least one of the plurality of ring-shaped channels, One or more sensors configured to collect information about the liquid in the plurality of ring-shaped channels, A control device configured to receive the information from one or more of the sensors, the control device which operates the carbon reservoir, the temperature device and the vertical lock according to the collected information, A system that includes this.

2. The system according to claim 1, wherein the plurality of ring-shaped channels are concentric.

3. The system according to claim 1, wherein the plurality of ring-shaped channels and the central container include a base and side walls extending upward from the base.

4. The system according to claim 1, further comprising an outlet pipe connected to the tube, wherein the outlet pipe is configured to transfer the processed liquid from the central container to a remote tank.

5. The system according to claim 1, wherein the reactor is configured to operate in an aquaculture system operating at a water temperature of 10 to 30°C.

6. The system according to claim 1, wherein the plurality of ring-shaped channels include at least an outer ring surrounding an inner ring, and the entrance is connected to the outer ring-shaped channel.

7. The system according to claim 6, wherein the outer ring includes a deflection plate positioned substantially in close proximity to the inlet, thereby the deflection plate modulates the direction of the liquid flow within the outer ring.

8. The system according to claim 6, wherein the outer ring and the inner ring include one or more movable vertical locks configured to regulate the flow of liquid within the rings.

9. A method for removing a compound from a liquid, The wastewater flow is received into one of several ring-shaped channels, The wastewater is forcibly flowed in one direction along the plurality of ring-shaped channels, Forming a sludge layer at the base of the plurality of ring-shaped channels, The sludge layer is digested by fermentative bacteria in the lower part of the sludge layer, A method that includes this.

10. The aforementioned digestion further, CO 2 The method according to claim 9, comprising a fermentation process that results in the production of gas and volatile fatty acids (VFAs).

11. The method according to claim 9, further comprising absorbing geosmin and 2-methylisoborneol into sludge particles in the sludge layer, and subsequently decomposing them with terpene-degrading bacteria.

12. Maintaining the sludge within a given temperature range, To detect the heating conditions of the sludge layer, Heating the aforementioned sludge, The method according to claim 9, further comprising:

13. To detect the height of the sludge level, Moving the vertical lock in response to the detection of the height of the sludge level, The method according to claim 9, further comprising:

14. The method according to claim 13, wherein one or more of the vertical locks move upward and downward, and the upper position of the vertical locks obstructs the passage of liquid within the ring.

15. The method according to claim 9, further comprising detecting carbon restriction conditions and injecting carbon into the fermentation layer of the sludge.

Images