Degradation of off-flavor compounds in aquaculture systems

Abstract

A reacting canister utilizing transparent optical fiber technology coated with a photo-catalyst and a plasmonic layer, including yttrium aluminum garnet nanoparticles, disposed between the optical fiber and the photo-catalyst to degrade off-flavor compounds in aquacultured aquatic life. The degradation of off-flavored compounds—including 2-methylisoborneol—can be significantly enhanced by increasing the surface area of the catalyst. Coating individual transparent optical fibers and aligning those fibers in a canister configuration allows the treatment of large volumes of water in portable and scalable reactors. Once the fluid is treated, the fluid is returned to the reservoir containing the aquacultured aquatic life.

Claims

1. A method of preserving freshness and increasing the harvesting time of aquacultured aquatic life comprising: delivering a fluid from a reservoir to an inlet disposed within a housing of an aquaculture reacting canister wherein the aquaculture reacting canister comprises a plurality of transparent optical fibers, each coated with a photo-catalyst; and a plasmonic layer disposed between the transparent optical fiber and the photo-catalyst coating; passing the fluid through the aquaculture reacting canister, such that via an advanced oxidation process, off-flavor compounds within the fluid are degraded when an ultraviolet light is passed through the transparent optical fiber; and returning the fluid as it exits through an outlet disposed within the housing of the aquaculture reacting canister to the reservoir, thereby preserving the freshness and decreasing the harvesting time of fish.

2. The method of claim 1, wherein the plasmonic layer comprises yttrium aluminum garnet nanoparticles.

3. The method of claim 1, wherein the plurality of transparent optical fibers are packed and intercalated with an uncoated transparent optical fiber.

4. The method of claim 1, wherein the photo-catalyst is applied to the plurality of transparent optical fibers using a slurry-spray coating process to prevent the photo-catalyst from leaching into an environment surrounding the plurality of transparent optical fibers.

5. The method of claim 1, wherein the off-flavor compounds are 1,10-dimethyl-trans-9-decalol and 2-methylisoborneol.

6. The method of claim 1, having two or more aquaculture reacting canisters connected in parallel or in series.

7. The method of claim 1, wherein the plurality of coated transparent optical fibers are aligned and arranged in the aquaculture reacting canister in a configuration that maximizes a surface area of the photocatalyst.

8. The method of claim 1, wherein the method further comprises actuating the fluid through a bead column, the bead column comprising: cactus mucilage in fluid communication with the fluid as it exits the aquaculture reacting canister, whereby the off-flavor compounds are further removed from the fluid.

9. The method of claim 1, wherein the aquaculture reacting canister further comprises baffles to support the plurality of transparent optical fibers and restrict fluid flow through the aquaculture reacting canister, thereby increasing contact time between the fluid and the photo-catalyst.

10. The method of claim 1, wherein the ultraviolet light is a fluorescent black light blue bulb, whereby photons emitted from the fluorescent black light blue bulb reacts with the photo-catalyst, thereby removing off-flavor compounds from the fluid.

11. The method of claim 1, wherein the reacting canister further comprises a light reflective housing, thereby maximizing a number of photons reacting with the photo-catalyst.

12. The method of claim 1, wherein the photo-catalyst is titanium dioxide (TiO.sub.2).

13. A method of degrading 2-methylisoborneol in water using a recirculating aquaculture system, the method comprising the steps of: delivering the water from a reservoir to an inlet disposed within a housing of an aquaculture reacting canister; wherein the aquaculture reacting canister comprises a plurality of transparent optical fibers, each coated with a photo-catalyst; and a plasmonic layer disposed between the plurality of transparent optical fibers and the photo-catalyst coating; passing the water through the reacting canister, such that 2-methylisoborneol within the water is degraded via an advanced oxidation process when an ultraviolet light is passed through the plurality of transparent optical fibers; and returning the water as it exits through an outlet disposed within the housing of the reacting canister to the reservoir, thereby preserving the freshness and decreasing the harvesting time of fish.

14. The method of claim 13, wherein the plasmonic layer comprises yttrium aluminum garnet nanoparticles.

15. The method of claim 13, wherein the plurality of transparent optical fibers are packed and intercalated with an uncoated transparent optical fiber.

16. The method of claim 13, wherein the photo-catalyst is applied to the plurality of transparent optical fibers using a slurry-spray coating process to prevent the photo-catalyst from leaching into an environment surrounding the plurality of transparent optical fibers.

17. The method of claim 13, wherein the aquaculture reacting canister further comprises a bead-column, wherein the bead column includes cactus mucilage in fluid communication with the water exiting the reacting canister, whereby the 2-methylisoborneol is further removed from the water.

18. The method of claim 13, wherein the ultraviolet light is a fluorescent black light blue bulb, whereby photons emitted from the fluorescent black light blue bulb reacts with the photo-catalyst, thereby removing the 2-methylisoborneol from the water.

19. The method of claim 13, wherein the photo-catalyst is titanium dioxide (TiO.sub.2).

20. A method of degrading off-flavor compounds in a fluid using a recirculating aquaculture system, the method comprising the steps of: delivering a fluid from a reservoir to an inlet disposed within a housing of a first aquaculture reacting canister the first aquaculture reacting canister comprising a plurality of transparent optical fibers, each coated with a photo-catalyst; and a plasmonic layer disposed between the transparent optical fibers and the photo-catalyst coating; passing the fluid through the first aquaculture reacting canister, such that via an advanced oxidation process off-flavor compounds within the fluid are degraded when an ultraviolet light is passed through the plurality of transparent optical fibers of the first reacting canister; delivering the fluid as it exits through an outlet disposed within the housing of the first reacting canister to an inlet disposed within the housing of a second aquaculture reacting canister, the second aquaculture reacting canister comprising a plurality of transparent optical fibers coated with a photo-catalyst; and a plasmonic layer disposed between the transparent optical fiber and the photo-catalyst coating; passing the fluid through the second aquaculture reacting canister, such that via an advanced oxidation process off-flavor compounds within the fluid are degraded when an ultraviolet light is passed through the plurality of transparent optical fibers of the second aquaculture reacting canister; delivering the fluid as it exits through an outlet of the second aquaculture reacting canister to the reservoir, thereby preserving the freshness and degreasing harvesting time of fish.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:

(2) FIG. 1 is a schematic representation of ARC prototype for catalytic degradation of GSM and MIB.

(3) FIG. 2 is a schematic of the reactor design, according to an embodiment of the current invention.

(4) FIG. 3A depicts a reactor, according to an embodiment of the current invention.

(5) FIG. 3B depicts a reactor, according to an embodiment of the current invention.

(6) FIG. 4 is a schematic depicting the improvement of the photocatalytic process.

(7) FIG. 5A depicts Geosmin degradation with the TiO.sub.2 photocatalyst.

(8) FIG. 5B depicts Geosmin degradation with the TiO.sub.2+new plasmonic layer.

(9) FIG. 6A depicts MIB degradation with the TiO.sub.2 photocatalyst.

(10) FIG. 6B depicts MIB degradation with the TiO.sub.2+new plasmonic layer.

(11) FIG. 7 depicts the cactus mucilage (beads column×large size container).

(12) FIG. 8 is a schematic of the system connected to a production tank of a recirculating freshwater system at Mote Marine Laboratory.

(13) FIG. 9 is a schematic of the system connected to a purge tank of recirculating seawater system at Mote Marine Laboratory.

(14) FIG. 10A depicts MIB before (left bars), and after treatment with the system connected. The middle bars indicate concentrations after reactors, and the right bars indicate concentrations after the entire system. The system was connected to a purge tank of a recirculating freshwater system at Mote Marine Laboratory.

(15) FIG. 10B depicts Geosmin before (left bars), and after treatment with the system connected. The middle bars indicate concentrations after reactors, and right bars indicate concentrations after the entire system. The system was connected to a purge tank of a recirculating freshwater system at Mote Marine Laboratory.

(16) FIG. 10C depicts MIB before (left bars) and after treatment with the system connected. The middle bars indicate concentrations after reactors, and the right bars indicate concentrations after the entire system. The system was connected to a purge tank of a recirculating freshwater system at Mote Marine Laboratory.

(17) FIG. 10D is a line graph illustrating MIB before and after treatment with the system connected, concentrations after reactors, and concentrations after the entire system. The system was connected to a purge tank of a recirculating freshwater system at Mote Marine Laboratory.

(18) FIG. 11 depicts the removal of MIB and Geosmin from a production tank of a recirculating freshwater system at Mote Marine Laboratory after treatment with the system.

(19) FIG. 12A depicts MIB normalized concentration prior to treatment with the system connected to a purge tank of recirculating seawater system at Mote Marine Laboratory.

(20) FIG. 12B depicts Geosmin normalized concentration prior to treatment with the system connected to a purge tank of recirculating seawater system at Mote Marine Laboratory.

(21) FIG. 12C depicts MIB normalized concentration after treatment with the system connected to a purge tank of recirculating seawater system at Mote Marine Laboratory.

(22) FIG. 12D depicts Geosmin normalized concentration after treatment with the system connected to a purge tank of recirculating seawater system at Mote Marine Laboratory.

(23) FIG. 13A depicts the removal of MIB from a purge tank of recirculating seawater system at Mote Marine Laboratory after treatment with the current system.

(24) FIG. 13B depicts the removal of Geosmin from a purge tank of recirculating seawater system at Mote Marine Laboratory after treatment with the current system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(25) In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part thereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention.

(26) As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the context clearly dictates otherwise.

(27) The current inventors have studied the degradation of GSM and MIB previously, for example in “Removal of Off-Flavor Compounds in Aquaculture Food Products: Optimizing New Techniques for Sustainable Aquaculture Systems”, Final Academic Progress Report, December 2013, pp. 1-71, Fresh From Florida, which is incorporated herein by reference in its entirety.

(28) In an embodiment, the current invention is a catalytic reactor using catalyst-coated optical fiber technology that allows the control of light and its emission mode to optimize catalytic degradation of off-flavor compounds quantitatively. This degradation can be significantly enhanced by increasing the surface area of the catalyst. Coating individual transparent optical fibers and aligning them in a canister configuration allows the treatment of large volumes of water in portable and scalable reactors.

(29) Methods

(30) The current methodology proposes the design of a technology capable of removing off-flavor compounds at a larger scale (treating approximately 50-60 GPM) for RAS or intensified systems used by various aquaculture operations.

(31) Catalyst-coated fiber optics greatly enhance the surface contact area and degradation action of GSM and MIB via an advanced oxidation process (AOP). Fiber optics are now affordable technology and have greatly enhanced electronic communications and improved illumination technologies. An aquaculture reacting canister (ARC) was developed with flexible, transparent fibers coated with immobilized TiO.sub.2 photo-catalyst that is slurry-spray-coated onto the transparent fibers in two different configurations, permitting optimization of its effectiveness. See FIG. 4. In both configurations, a plasmonic layer that includes yttrium aluminum garnet (YAG) nanoparticles is positioned between the photo-catalyst and the substrate, as shown in FIG. 4.

(32) The coating process has been studied in the current inventors' previous research projects, and it has been determined that this technique is quite robust for underwater applications and where the catalyst does not leach out from the substrate. The first coating method involves covering entire transparent glass fibers with the catalyst. These fibers can be packed and intercalated with uncoated fibers emitting at the wavelength for the catalyst to activate its organic degradation potential. The light inside the fibers will undergo total internal reflection, so the fibers will act as waveguides and propagate in multiple-mode configurations to enhance intensity and light reflection.

(33) In the second coating method, a mesh can be used to mask the catalyst coating area, but all fibers are packed together.

(34) The effect of having light emitting through naked fibers into the coated fibers can be compared against the effect of having attenuated light from within the optical fiber to reflect on the catalyst-coated surface area. The effect that each method will have on the degradation of GSM and MIB can be a benchmark for determining which technique is more effective so that bundles of fibers can be incorporated into canisters that allow the flow needed for treating large amounts of water from the purging tanks.

(35) Since the thickness of fiber optics is not larger than a human hair, they can be coated effectively with this technique and packed into canisters, as shown in FIG. 1. See also FIG. 7. The water can be continuously recirculated and sampled at the vent outlets. In turn, an in situ off-flavor detection method using refractive index changes can be coupled with the ARC for improving its applicability. Baffles can be used to position and support the fiber bundles and restrict the water flow to increase the contact time inside the ARC. See FIGS. 1, 2, 3A, and 3B. The research parameters involved in the testing include the following variables: Packing density of fibers Staking of canisters Position of baffles Light intensity Modulation and phase of light Retention time Volume Reaction rate coefficient Water pressure drop Water flow patterns inside the tank

(36) Theoretical models will be used to simulate the response on the performance of the ARC unit and its operating conditions. ASPEN PLUS, COMSOL (engineering design software), or other suitable software can be used to determine model parameters, initial conditions of operation, final concentrations, volumes, temperature, pressure, and flows. See FIGS. 5A-5B and 6A-6B for theoretical results.

STUDY/EXAMPLE

(37) The system was tested on recirculating aquaculture system at Mote Marine Laboratory under two different conditions. A set of four (4) reactors and one (1) biobead column was connected to a production tank of the recirculating freshwater system. The production tank was continuously running and monitored for two (2) weeks (see FIG. 8). Another set of eight (8) reactors and two (2) biobead columns were connected to a purge tank of recirculating seawater system and continuously ran and monitored for 30 days (see FIG. 9).

(38) In the production tanks, the concentration of Geosmin and MIB was considerably higher than concentrations on the purge tanks. In the production tanks, there was a continuous production of off-flavors, and the initial concentrations before the system had a natural variation along the evaluated time, MIB (30 to 60 ng/L), and Geosmin (15 to 35 ng/L). Initial concentrations of MIB and Geosmin, on the purge tank, were 5.1 to 1.7 ng/L and 1.3 to 0.1 ng/L, respectively.

(39) Even though the input concentrations were as high as 60 ng/L, the system was always able to keep the concentrations of MIB and Geosmin below 10 ng/L (FIGS. 10A-10D; Tables 1-2). During evaluation time, the removal percentage of MIB and Geosmin on the freshwater production tank was always equal or higher than 80% (FIG. 11; Table 3).

(40) TABLE-US-00001 TABLE 1 Results: MIB GSM Sample ppt ppt A1h1 29.0 17.2 A2h1 31.1 17.4 B1h1 6.3 3.8 B2h1 5.9 2.4 C1h1 4.7 2.6 C2h1 5.0 1.8 A1h2 34.9 15.9 A2h2 34.1 18.8 B1h2 8.5 2.7 B2h2 6.5 2.7 C1h2 6.3 2.4 C2h2 5.1 1.8 A1D1 30.4 14.3 A2D1 36.3 19.7 B1D1 8.9 3.0 B2D1 7.2 3.3 C1D1 6.7 2.7 A1d2 53.4 30.3 A2d2 47.4 28.5 B1d2 9.5 6.6 B2d2 9.9 6.2 C1d2 8.6 5.4 C2d2 9.0 5.7 A1w1 62.7 34.1 A2w1 56.0 29.0 B1w1 9.8 5.6 B2w1 7.9 6.1 C1w1 7.8 5.8 C1w2 8.6 5.4 A1w2 46.5 27.1 A2w2 50.0 33.6 B1w2 8.4 5.9 B2w2 9.2 5.2 C1w2 8.6 5.4 C2w2 8.9 5.6

(41) TABLE-US-00002 TABLE 2 Average Concentration (ppt) sampling 1 1 2 2 24 24 48 48 168 168 336 336 point MIB GSM MIB GSM MIB GSM MIB GSM MIB GSM MIB GSM Before 30.1 17.3 34.5 17.3 33.4 17.0 50.4 29.4 59.3 31.6 48.3 30.3 After Reactors 6.1 3.1 7.5 2.7 8.1 3.2 9.7 6.4 8.9 5.8 8.8 5.6 After R + B 4.9 2.2 5.7 2.1 6.7 2.7 8.8 5.6 8.2 5.6 8.8 5.5 83.8 87.2 83.5 87.7 79.9 83.9 82.5 81.1 86.2 82.3 81.9 81.9

(42) TABLE-US-00003 TABLE 3 Removal (%) after 1 after 2 after 1 after 2 after 1 after 2 sampling hour hours day days week weeks point MIB GSM MIB GSM MIB GSM MIB GSM MIB GSM MIB GSM B after 79.6 82.1 78.3 84.3 75.8 81.4 80.7 78.3 85.1 81.6 81.7 81.7 reactors C after beads 83.8 87.2 83.5 87.7 79.9 83.9 82.5 81.1 86.2 82.3 81.9 81.9 Beads 4.2 5.1 5.2 3.4 4.1 2.4 1.8 2.8 1.1 0.7 0.1 0.2

(43) The system was able to treat 629 mL/min, and after 30 days of continuous operation, the water in the seawater purge tank was off-flavors free, with concentrations below the limit of detection (see FIGS. 12A-12B (initial concentrations) vs. FIGS. 12C-12D (after system)). Removal percentage equal to or higher than 90% was obtained during all evaluated times (FIGS. 13A-13B). See Tables 4-10.

(44) TABLE-US-00004 TABLE 4 Sample Dilution MIB GSM 1hA1 3 5.29 1.38 1hA2 3 4.85 1.28 1hB1 3 0.39 0.13 1hB2 3 0.31 0.10 1hC1 3 0.16 0.09 1hC2 3 0.24 0.03 2hA1 3 4.06 1.34 2hA2 3 5.76 1.18 2hB1 3 0.45 0.08 2hB2 3 0.29 0.14 2hC1 3 0.13 0.03 2hC2 3 0.14 0.07 2dA1 3 4.80 1.22 2dB1 1 0.32 0.10 2dC1 1 0.10 0.04 2wA1 1 2.62 0.52 2WA2 1 2.49 0.40 2WB1 1 0.03 0.00 2WB2 1 0.02 0.00 2WC2 1 0.00 0.00 2WC1 1 0.01 0.00 M1A1 1 1.41 0.15 M1A2 1 1.95 0.06 M1B1 1 0.02 0.00 M1B2 1 0.01 0.00 M1C1 1 0.02 0.00 M1C2 1 0.00 0.00

(45) TABLE-US-00005 TABLE 5 average average Location MIB Location GSM 1 h A 5.07 1 h A 1.33 B 0.35 B 0.11 C 0.20 C 0.06 2 h A 4.91 2 h A 1.26 B 0.37 B 0.11 C 0.14 C 0.05 2 d A 4.80 2 d A 1.22 B 0.32 B 0.10 C 0.10 C 0.04 2 w A 2.56 2 w A 0.46 B 0.02 B 0.00 C 0.01 C 0.00 1 M A 1.68 1 M A 0.11 B 0.01 B 0.00 C 0.01 C 0.00

(46) TABLE-US-00006 TABLE 6 average MIB Location 1 h 2 h 2 d 2 w 1 M A 5.07 4.91 4.80 2.56 1.68 B 0.35 0.37 0.32 0.02 0.01 C 0.20 0.14 0.10 0.01 0.01 average MIB days Location 0.1 0.2 2 15 30 A 5.07 4.91 4.80 2.56 1.68 B 0.35 0.37 0.32 0.02 0.01 C 0.20 0.14 0.10 0.01 0.01

(47) TABLE-US-00007 TABLE 7 average GSM Location 1 h 2 h 2 d 2 w 1 M A 1.33 1.26 1.22 0.46 0.11 B 0.11 0.11 0.10 0.00 0.00 C 0.06 0.05 0.04 0.00 0.00 average GSM days Location 0.1 0.2 2 15 30 A 1.33 1.26 1.22 0.46 0.11 B 0.11 0.11 0.10 0.00 0.00 C 0.06 0.05 0.04 0.00 0.00

(48) TABLE-US-00008 TABLE 8 removal % MIB Location 1 h 2 h 2 d 2 w 1 M reactors 93.15 92.45 93.32 99.16 99.16 R + B 96.02 97.22 97.88 99.74 99.50 Beads 2.87 4.77 4.56 0.58 0.34 removal % MIB days Location 0.1 0.2 2 15 30 Reactors 93.15 92.45 93.32 99.16 99.16 Beads 2.87 4.77 4.56 0.58 0.34

(49) TABLE-US-00009 TABLE 9 removal % GSM Location 1 h 2 h 2 d 2 w 1 M reactors 91.37 91.48 91.46 99.57 99.59 R + B 95.58 95.86 97.00 99.92 99.78 Beads 4.22 4.38 5.54 0.35 0.19 removal % GSM days Location 0.1 0.2 2 15 30 Reactors 91.37 91.48 91.46 99.57 99.59 Beads 4.22 4.38 5.54 0.35 0.19

(50) TABLE-US-00010 TABLE 10 MIB days 0.1 0.2 2 15 30 A 5.07 4.91 4.80 7.56 1.68 C/Co 1.00 0.97 0.95 0.50 0.33 C 0.20 0.14 0.10 0.01 0.01 C/Co 1.00 0.68 0.50 0.03 0.04 average GSM days Location 0.1 0.2 2 15 30 A 1.33 1.26 1.22 0.46 0.11 C/Co 1.00 0.95 0.91 0.35 0.08 C 0.06 0.05 0.04 0.00 0.00 C/Co 1.00 0.89 0.62 0.01 0.00

(51) The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

(52) It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.