Macroalgae biomass production

Abstract

The present invention relates to systems and methods for the cultivation and processing of high quality macroalgae, particularly for the cultivation of edible seaweed on a commercial scale.

Claims

1. A land-based system for the production of macroalgae, the system comprising: a. a reservoir containing pristine seawater, wherein the pristine seawater is obtained from at least one coastal well, and is filtrated through sand and rock layers separating the coastal well from the sea, b. at least one inoculum tank comprising at least one of a gas distribution system, a jet water system or a combination thereof, the at least one inoculum tank containing a culture medium and pieces of a macroalgae young thalli, wherein the culture medium comprises pristine seawater from the reservoir; and c. at least one cultivation pond comprising at least one of a gas distribution system, a jet water system or a combination thereof, the at least one cultivation pond containing a culture medium and macroalgae, wherein the culture medium comprises pristine seawater from the reservoir.

2. The land-based system of claim 1, wherein the system further comprises a mesh covering the at least one inoculum tank and/or cultivation pond.

3. The land-based system of claim 1, wherein the temperature of the pristine seawater is from about 2 C. to about 30 C.

4. The land-based system of claim 3, wherein the temperature of the pristine seawater is a constant temperature of from about 20 C. to about 25 C.

5. The land-based system of claim 4, wherein the temperature of the pristine seawater is about 22 C.

6. The land-based system of claim 1, wherein the pristine seawater is essentially free from pollutants and pathogens.

7. The land-based system of claim 6, wherein the pristine seawater is rich in essential minerals selected from the group consisting of calcium, magnesium, carbonates and any combination thereof.

8. The land-based system of claim 1, wherein the pristine seawater is obtained from a deep costal well.

9. The land-based system of claim 1, wherein the pristine seawater is purified seawater obtained from a water treatment system.

10. The land-based system of claim 9, wherein the seawater treatment system comprises a sand filter, ozonation tank and active carbon filter.

11. The land-based system of claim 1, wherein the culture medium consists of the pristine seawater.

12. The land-based system of claim 1, wherein the culture medium further comprises at least one additional nutrient selected from the group consisting of nitrogen, phosphate and a combination thereof.

13. The land-based system of claim 1, wherein the inoculum tank has a half-ball shape.

14. The land-based system of claim 13, wherein the inoculums tank has a volume of 0.5-3 cubic meters (m.sup.3).

15. The land-based system of claim 1, wherein the opening of the cultivation pond has a quadrangle configuration, a U shape or cube shape.

16. The land-based system of claim 1, wherein the gas distribution system comprises a gas source device and a plurality of gas tubes comprising at least one gas inlets and a plurality of gas outlets, wherein the plurality of gas tubes is positioned along the base of the cultivation pond.

17. The land-based system of claim 1, wherein the pH of the culture medium is kept below 9.5.

18. The land-based system of claim 1, wherein the macroalgae is of a genus selected from the group consisting of Ulva, Porphyra, Laminaria, Undaria, Eucheuma, Gracillaria, Sargassum, Codium, Furcellaria, Cladophora, Ascophyllum and Palmaria.

19. A method for cultivating macroalgae, the method comprising: a. providing at least one inoculum tank having a volume of 0.5-3.0 cubic meter (m.sup.3), containing a culture medium comprising pristine seawater; wherein the pristine seawater is obtained from at least one coastal well, and is filtrated through sand and rock layers separating the coastal well from the sea; b. inoculating the inoculum tank with about 100-200 g of fragmented young thalli of a macroalgae; c. growing the macroalga within the inoculums tank to reach a macroalgae inoculum total fresh mass of about 2-15 kg; d. transferring the macroalgae inoculum mass or a part thereof to a cultivation pond having a volume of 5-10 m.sup.3 comprising operating gas distribution system and/or operating array of jet water pipes, containing a culture medium comprising pristine seawater; e. growing the macroalgae inoculum mass within the 5-10 m.sup.3 cultivation pond to reach a macroalgae total fresh mass of about 10-60 kg; f. transferring the macroalgae mass or a part thereof to a cultivation pond having a volume of 20-30 cubic meter comprising operating gas distribution system and/or operating array of jet water pipes, containing a culture medium comprising pristine seawater; g. growing the macroalgae within the 20-30 m.sup.3 cultivation pond to reach a macroalgae total fresh mass of about 100-200 kg; h. harvesting the macroalgae mass; or optionally i. transferring at least part of the macroalgae mass of the 20-30 m.sup.3 cultivation pond to a cultivation pond having a volume of 200-500 m.sup.3 comprising operating gas distribution system and/or operating array of jet water pipes, containing culture medium comprising pristine seawater; j. growing the macroalgae within the 200-500 m.sup.3 cultivation pond to reach a macroalgae total fresh mass of at least 400-1,000 kg; and k. harvesting the macroalgae fresh mass.

20. The method of claim 19, wherein step (i) comprises (1) transferring at least part of the macroalgae mass of the 20-30 m.sup.3 cultivation pond to a cultivation pond having a volume of 40-70 m.sup.3 comprising operating gas distribution system and/or operating array of jet water pipes, containing culture medium comprising pristine seawater; (2) growing the macroalgae within the 40-70 m.sup.3 cultivation pond to reach a macroalgae fresh mass of about 100-200 kg; (3) harvesting the macroalgae mass; or optionally (4) transferring at least part of the macroalgae mass of the 40-70 m.sup.3 cultivation pond to a third cultivation pond having a volume of 200-500 cubic meter comprising operating gas distribution system and/or operating array of jet water pipes, containing culture medium comprising pristine seawater.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a schematic presentation of a cultivation pond.

(2) FIG. 2 is a schematic presentation of typical design of cultivation ponds.

DETAILED DESCRIPTION OF THE INVENTION

(3) Referring to FIG. 1, providing a top cross section of an exemplary cultivation pond, the cultivation pond of 200 m.sup.3 (2) contains gas distribution system (4) comprising a plurality of gas tubes (6) located on the base (8) of the cultivation pond at a distance of 40 cm from each other (10). The cultivation pond (2) further contains a plurality of liquid inlet ports (12) and outlet ports (14).

(4) Referring to FIG. 2, a typical design of cultivation ponds contains a first cultivation pond having a volume of 6 m.sup.3 (16), a second cultivation pond having a volume of 18 m.sup.3 (18) and a third cultivation pond having a volume of 200 m.sup.3 (2).

(5) Pristine Seawater

(6) The water used throughout the system of the present invention is high quality seawater typically obtained from deep costal well. The principal advantage of using seawater from costal wells is in the natural filtration of the water through the sand and rock layers separating the well from the sea. The main benefit of using well seawater is that the water obtained is essentially free from pollutants such as heavy metals, PCBs, dioxins (2,3,7,8-tetrachlorodibenzo para dioxin (TCDD) and chemically related polychlorinated dibenzo para dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)) and from any flora or fauna species that can interfere with the culture of the target macroalgae, including pathogenic or parasitic flora and/or fauna. As used herein, the term essentially free from heavy metal refers to heavy metals content within the acceptable limits for drinking water.

(7) According to certain exemplary embodiments, the system of the present invention further comprises a deep costal well.

(8) Inoculum Growth

(9) Having high quality algal inoculums is a key feature in successful growth of macroalgae. Its growth in the system of the present invention ensures a constant source of high quality algae for all stages.

(10) 100-200 liter tanks at a shape of half-ball are used. Before each growth cycle the tanks are cleaned from any organic remains, typically with water, or with water and chlorine. The tanks are inspected not to include any remaining of parasitic or other non-desired algae or phytoplankton organisms. Typically, inoculum growth starts at a small tank of 100 liter filled with pristine seawater to a height of at least about 50 cm (measured at the half-ball center). It is of high importance that the algae used for starting the inoculums are also clean from any other organism. The macroalgae are therefore typically washed with water and/or brushed gently. Clean algae are then placed in the tank and the water flow is adjusted to 10-35 liters/hour for the first three days. Thereafter, the water flow rate is adjusted according to the algae growth rate and water pH. Typically, the water flow rate is elevated to 100 liter/h. It is however should be explicitly understood that the time of growth and the water flow rate depended on the algae species grown and the environmental conditions, particularly the water and ambient air temperature and the duration and intensity of sunlight.

(11) It is further of high importance to keep young thalli of the macroalgae in the inoculum. This is achieved by hand fragmentation of the growing algal mass.

(12) Optionally, when the algae within the inoculum tank reach a mass of at least 0.6 Kg, typically between 0.6 Kg and 1.0 Kg, the algal mass is transferred to a larger inoculums tank of 200 liter, containing pristine seawater at a height of at least about 30 cm (measured at the half-ball center). The water flow rate in the 200 liter inoculum tank is adjusted to 70-110 liter/h for the first 3 days of algal growth, and adjusted thereafter according to the observed algae growth rate and water pH. Growth is continued until the algae reach a mass sufficient to inoculate a 5-10 m.sup.3 cultivation pond. Typically, when the algae reach a total mass of at least 2 Kg, typically between 3 Kg to 6 kg, the algae are harvested to serve as the inoculums of the 5-10 m.sup.3 cultivation pond.

(13) At times, the inoculum growth requires the addition of nitrogen and phosphorous. Amounts added are those added to the inoculum tank(s) of 2 g nitrogen per m.sup.2 per day and 0.6 g phosphorous per m.sup.2 per day. Nitrogen is added as ammonium sulfate (NH.sub.4).sub.2SO.sub.4 (21% N) and phosphorous as mono-ammonium phosphate (NH.sub.4H.sub.2PO.sub.4) using a dripping system.

(14) 5-10 m.sup.3 Cultivation Pond

(15) The cleansing requirements of the cultivation ponds and of the algae should be kept throughout the growth process, i.e. the ponds and the algae must be cleaned from any organic remaining and/or non-desired organisms.

(16) The cultivation pond having a volume of 5-10 m.sup.3, typically having a volume of 6 m.sup.3 is filled with pristine seawater from the reservoir such that the water height is not exceeding 100 cm, typically the height being about 85 cm. Algae inoculum of at least 3 Kg is added. The 5-10 m.sup.3 cultivation pond can receive inoculum of 3-10 Kg while keeping good growth rate and obtaining algae at a good quality. Optimal inoculum mass is typically between 4-5 Kg.

(17) Algal circulation, suspension and uniform distribution are achieved by the operation of the gas distribution system typically at air supply rate of 2.5-3.0 m.sup.3/m.sup.2 and/or, by the operation of jet water pipes, typically at a jet water flow of 1-3 m.sup.3/h. When required, nitrogen and phosphorous are added as described for the inoculum tank above. Macroalgae are grown in the 5-10 m.sup.3 cultivation pond to reach fresh mass of 10-60 Kg. Water flow to support optimal growth is set to 1 m.sup.3/h. The duration required to reach the desired algal mass depend on the environmental conditions, particularly on the day length. Typically, the algal mass is reached within about 7 days of growth in Israel during summertime and within about 14 days in Israel during wintertime. Typically, 10-50 Kg of fresh algal mass is harvested from the 5-10 m.sup.3 cultivation pond.

(18) 20-30 m.sup.3 Cultivation Pond

(19) The cultivation pond having a volume of 20-30 m.sup.3, typically having a volume of 18 m.sup.3 is filled with pristine seawater from the reservoir. As for the 5-10 m.sup.3 cultivation pond, the seawater height is kept at up to 100 cm, typically the height being about 85 cm, and water flow is set to 2 m.sup.3/h. Macroalgae grown in the 20-30 m.sup.3 cultivation pond may form the starting material for the larger, 40-70 m.sup.3 and/or for the 200-500 m.sup.3 cultivation ponds or can be harvested for further processing of the macroalgae product. Partial harvest may be also performed such that the remaining material in the 20-30 m.sup.3 cultivation pond forms a starter for a second harvest from the same pond. Several harvest rounds can be performed in the 20-30 m.sup.3 cultivation pond; the number of harvests depends on the algal growth rate and on the quality of the macroalgae produced. Typically, algal fresh mass of about 100-200 Kg is produced within 7 days (Israel summertime) or within 14-21 days (Israel wintertime).

(20) Algal circulation, suspension and uniform distribution and nutritional addition are performed as described above.

(21) 40-70 m.sup.3 Cultivation Pond

(22) Optionally, a cultivation pond having a volume of 40-70 m.sup.3 also forms part of the systems and methods of the present invention. The cultivation pond, typically having a volume of 54 m.sup.3, is filled with pristine seawater from the reservoir. As for the previous cultivation ponds, the seawater height is kept at up to 100 cm, typically at about 85 cm. Water flow is set to about 0.8 m.sup.3/h (Israel wintertime) or to 2 m.sup.3/h (Israel summertime). The algal mass harvested from the 40-70 m.sup.3 cultivation pond may serve as starting material to additional pond(s) or may be harvested. Typically, macroalgae grown in the 40-70 m.sup.3 cultivation pond form the starting material for the largest 200-500 m.sup.3 cultivation ponds or can be harvested for further processing of the macroalgae product. Partial harvest may be also performed such that the remaining material in the 40-70 m.sup.3 cultivation pond forms a starter for a second harvest from the same pond. Several harvest rounds can be performed in the 40-70 m.sup.3 cultivation pond; the number of harvests depends on the algal growth rate and on the quality of the macroalgae produced. Typically, the average algal fresh mass obtained yearly from this cultivation pond is about 300-400 Kg.

(23) Algal circulation, suspension and uniform distribution and nutritional addition are performed as described above.

(24) 200-500 m.sup.3 Cultivation Pond

(25) The 200-500 m.sup.3 cultivation pond forms the largest growth volume in the system of the present invention. The volume of this cultivation pond is typically about 200 m.sup.3, but larger ponds of 500 m.sup.3 and up to 1,000 m.sup.3 can be also used. Water flow is typically set to 1.4 m.sup.3/h. The algal mass harvested from the 20-30 m.sup.3 and/or from the 40-70 m.sup.3 cultivation pond serves as the starting material. Macroalgae are grown in the 200-500 m.sup.3 cultivation pond at algal density of about 1.5-2 Kg/m.sup.2, which provides for several harvests. Typically, algal fresh mass of about 500-600 Kg is produced within about 6 weeks (summertime) or within 12 weeks (wintertime) in cultivation at a volume of 200 m.sup.3.

EXAMPLES

Example 1

Production of Ulva Batch GH 6/7

(26) Growth was started in a small inoculum tank of 0.5 m.sup.3. 150 gr of the algae at an average size of 2-15 cm.sup.2 were inoculated in the small tank and left to grow for 13 days. Manual fragmentation of the growing algae to keep the size at 2-15 cm.sup.2 was made as necessary, typically once a day. Average growth rate was 510 gr/m.sup.2/day. The algae reached weight of 2.15 Kg. 700 gr of this mass were transferred to a larger inoculum tank (1.5-2 m.sup.3) and growth continued for additional 10 days. The measured growth rate was 440 gr/m.sup.2/day and total algal weight of 4.24 Kg was produced. On the 11.sup.th day, all the algal mass was transferred to a first cultivation pond of 6 m.sup.2. Algae were grown in this cultivation pond for 13 days at an average growth rate of 200 gr/m.sup.2/day. After total of 36 days of growth the complete algal mass (20 Kg) was transferred to a second cultivation pond of 18 m.sup.2. After additional 18 days of growth at an average growth rate of 120 gr/m.sup.2/day algae were harvested. Total yield of 70 Kg after a total growth period (from the first inoculum) of 54 days was obtained.

Example 2

Production of Ulva Batch GH 3/4

(27) Growth was started in a small inoculum tank of 0.5 m.sup.3. 150 gr of Ulva (batch GH 3/4) at an average size of 2-15 cm.sup.2 were inoculated in the small tank and left to grow for 15 days. Fragmentation of the growing algae to keep the size at 2-15 cm.sup.2 was made manually as necessary, typically once a day. Average growth rate was 180 gr/m.sup.2/day. On day 16 the algae reached the weight of 950 gr. 150 gr of this mass were transferred to a larger inoculum tank and growth continued for additional 20 days. The measured growth rate was 180 gr/m.sup.2/day and total algal weight of 4.63 Kg was produced. On the 21.sup.st day, all the algal mass was transferred to a first cultivation pond of 6 m.sup.2. The algae were grown in the first cultivation pond for 18 days at an average growth rate of 110 gr/m.sup.2/day. The complete algal mass obtained (17 Kg) was transferred to a second cultivation pond of 18 m.sup.2. After additional 21 days of growth at an average growth rate of 80 gr/m.sup.2/day algae were harvested. Total yield of 56.4 Kg after a total growth period (from the first inoculum) of 74 days was obtained.

(28) The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without undue experimentation and without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The means, materials, and steps for carrying out various disclosed functions may take a variety of alternative forms without departing from the invention.