PT94028B - ALGAS CULTURE RESERVOIR AND PROCESS FOR THEIR UTILIZATION - Google Patents

Abstract

PURPOSE: To culture algae and more particularly Chondrus crispus at a high yield by arranging obstacles on the course of a liquid medium driven by the impellers of an alga culture tank. CONSTITUTION: The culture tank 10 which has a somewhat flat elliptic annular form delineated between an outside wall 11 and a central nucleus 12 and includes at least one of the radial impellers 14 and discharge pipes 22 consist of at least two groups of the obstacles 18, 20. The one 20 is arranged on the axis of the central nucleus 12 and another 18 is arranged downstream of the impellers 14. The obstacle 18 has an angle of 90 to 160 deg. with the flow and the length thereof, if longest, is equal to half the width of the fluid flow. The sea water is supplied to this culture tank 10 which is then replenished with a carbon source, nitrogen source and phosphorus source. The pH of the medium is maintained at 8 to 9. The pH of the medium is maintained at 8.5 to 8.8 by adding an inorg. acid to the tank in some cases during long-term photosynthesis.

Description

The present invention relates to a macroscopic algae culture reservoir (10) fed by water, having a more or less flattened crown shape, defined between an outer wall (11) and a central core (12), at least one wheel with loops (14) arranged radially and obstacles (18.20).

SANOFI

ALGAE CULTURE RESERVOIR AND PROCESS FOR THEIR USE.

The invention also relates to a process for obtaining Chondrus crispus, which consists of growing the algae in the said reservoir, fed by seawater, and with additional sources of carbon, nitrogen and phosphorus.

The present invention relates to an air reservoir for the cultivation of macroscopic algae, in which the algae float in seawater that circulates there and to a culture process that uses this reservoir.

Algae are widely used by the pharmaceutical, chemical and food industries as a source of raw materials; certain species are even eaten fresh or rehydrated in different countries; but the collection of wild algae, particularly on the French coasts, is decreasing, and it is desirable to produce algae - at least certain species - grown in reservoirs fed with seawater and located outdoors on the banks, far from storms and the phenomena of tides.

Thus, numerous species of algae can be cultivated, such as, Chondrus cripus, Gigartina stellata, Calliblepharis ciliata et lanceolata, Laminaria sp., Solieria Chordalis, Cystoclonium purpureum, Palmaria palmata, Gracilaria sp., Uiva sp., Enteromorpha sp. Bryopsis .

With regard to certain algae, such as Chondrus, a red algae from which carrageenans, food-grade thickener polysaccharides are extracted, and more particularly, Chondrus cripus whose stocks are important in Europe, it is also desirable to find economically competitive culture conditions.

Some teams of experts have already studied this issue, such as that of R.G.S. Bidwell, Canada, which he described in Botanica Marina Vol. XXVIII p. 87-97 (1985) a reservoir for the cultivation of Chondrus crispus, still called Irish moss, fed with sea water, nutrients and carbon dioxide, the seaweed bracelet being ensured by the formation of air bubbles from the bottom of the reservoir , about 80 cm deep.

According to the authors, this device ensures intermittent illumination of the algae, favorable to their development and regularly distributes sources of carbon and other necessary nutrients well known to the specialist, while the vane wheel system, previously used for agitation by Simpson et Coli. and disgrace in Bot. Mar. 21 p. 229 - 235 (1978) is frankly less effective and profitable because plants circulate poorly and have a tendency to settle at the bottom of the reservoir, resulting in a slower crossing and an easier development of spirits and diseases.

Therefore, it would be desirable to find another device, since the agitation of the reservoir due to air blasting presents several drawbacks, a high consumption of energy and carbon dioxide, as well as a higher cost of making the reservoirs: they must be equipped with non-corrosive air supply tubes, and its depth should be 4 to 5 times, that of light penetration in order to ensure a correct brazing.

The reservoir according to the invention, due to its shape and the presence of obstacles conveniently placed in the path of the liquid medium, set in motion by a wheel with blades, allows the cultivation of water, in particular Chondrus cripus, in a temperate zone. medium sunny, as in the Costas da Manbha and the Atlantic in France, with excellent yields.

Algae develop quickly, under classic growing conditions, such as those described by R.G.S. Bidwell in the aforementioned document, or by Neish and Col. in the Canadian Journal of Botany 55 p. 2263 - 2271 (1977).

-5Productivity per unit area is ten to fifteen times higher than when the seaweed is in its natural environment; on the other hand, there was a slight difference in aspect between wild and cultivated algae in the reservoirs according to the invention and, above all, a difference in composition, since in the cultivated algae, there is practically no determined division , precursor of the Rappa carrageenan, but only this carrageenan; this allows the extraction by macerating the plant in slightly alkalized water, even though a basic treatment with pH 12 is necessary in order to transform the precursors and extract all the carrageenan from the wild plant.

the reservoir, according to the invention, has the shape of an elliptical crown in the horizontal plane, flattened according to its great axis, defined between an outer wall and an inner core that can be reduced to a simple plane, located on the great axis of the ellipse; this plane would be materialized, for example, by a wall that is on each side at a distance from the outer wall of the reservoir approximately equal to the small axis of the ellipse, in such a way that the liquid medium can circulate continuously around the central core; an equivalent reservoir, although more uncomfortable on the ground and slightly less effective, and consisting of a cylindrical crown comprised between 2 substantially homotetic ellipses; it is preferable that the length of the large axis is 2 to 8 times that of the small axis and that the wall is reasonably thick enough to ensure its resistance, which means about 8 cm to 1.80 m, according to material (earth, concrete, cemented bricks).

the reservoir (10), illustrated by way of example, with a view in the horizontal plane in figure 1, has an elliptical elongated shape. Only half of the reservoir was illustrated, the other half being symmetrical in relation to a vertical transverse plane of line XX.

The reservoir is bounded by an outer wall (11) and a central core (12), reduced in this embodiment to a wall that is at a certain distance from the two ends of the reservoir, which defines in this last one, a closed flow circuit for the water contained in the reservoir.

reservoir can be resting on the ground, semi-buried or buried. On the other hand, they are equipped with at least one wheel with blades (14), whose rotation ensures the circulation of the liquid medium around the central core (12) of the reservoir; its axis is therefore confused with the radius of the reservoir at the point considered and its blades (16) plunge into the water to a depth sufficient to set the liquid medium in motion throughout its height.

The specialist will calculate, in any case, the dimension, the dimension of the blades, the height of submersion in water, the speed of rotation of the axis according to the characteristics of the shape and dimensions of the reservoir and, in particular, the height of the water, taking into account that the velocity of displacement of the liquid must be sufficient to avoid an important development of the parasitic macrophyte algae, that is to say, practically greater than 0.30 m / second.

It is preferred, due to the fact that there is no dead zone that is heavily braced, to have two wheels 14,14 'in the reservoir, in diametrically opposite positions, particularly in the crown reservoirs, or in the case of flattened central core reservoirs, in the elongated part of the ellipse and cutting the 2 chains in the opposite direction as shown in Fig. 1, but the wheels cannot be on the reservoir's symmetry axis.

The distance between its two axes can go up to 2/3 of the length of the reservoir.

The height of the water in the reservoir depends on the species of algae grown, their density and size as well as the average exposure to sunlight; it will, in general, be between 0.3 m and 1 m, preferably close to 0.40 m in order to ensure a satisfactory circulation of the liquid and the lighting over a maximum depth.

Finally, and this is an important feature of the invention, the reservoir is provided with at least 2 groups of obstacles (18), (20) located on the path of the liquid medium, constituted, for example, by two small vertical walls. or slightly inclined preferably, leveling the upper level of the liquid, the length of which is at most equal to half the width of the liquid stream, one of the groups being located approximately along the major axis of the reservoir, in the extension of the central core (12); the other, downstream of the wheel or wheels (14.14 '), makes the chain an angle between 90 ° and 160 ° and, preferably, 130 °.

These obstacles create eddies and accelerate the current locally ensuring a better homogenization of the environment and the rise of algae to the water surface, the productivity of the culture is greatly improved in the presence of some obstacles, conveniently placed, preferably in the areas where the current tends towards a laminar regime or those in which the current will be at the retarder. On the contrary, the multiplication of obstacles or their over-dimensioning is unfavorable.

Thus, in the case of the reservoir represented in Fig. 1, equipped with the 4 obstacles indicated, the average productivity in a year is 2.5 times that of a reservoir in the same way, but only clamped by wheels with paddles.

On the other hand, as in the classical reservoirs, there is an unrepresented sea water inlet and, preferably, at the other end, a water outlet duct (22); this outlet is advantageously located behind an obstacle, so that the density of algae in the area is low.

Water feeding can be continuous or sequential; it must be sufficient to take the quantity of trace elements and potassium necessary for the development of algae and compensate for natural evaporation.

The configuration of the reservoir makes it possible to avoid water recycling, which is often installed over rectangular reservoirs in order to create a current in the medium.

Another object of the invention is the process of obtaining macroscopic algae, which consists of cultivating them in a reservoir according to the invention, fed with sea water and supplemented by sources of carbon, nitrogen and phosphorus. The usual nutrients, nitrogen and phosphorus, are injected at regular intervals, preferably interrupting the seawater circuit, which improves the absorption of the compounds by the algae and prevents a major loss in the effluents.

It also introduces carbon into the culture medium in the form of carbon dioxide, a carbonate or an organic carboxylic acid; the pH of the culture medium is, in general, between 8 and 9, and preferably between 8.5 and 8.8 during important photosynthesis periods, a mineral acid can be introduced in the medium in order to keep within these limits.

According to another aspect, the process of the invention, is introduced into the reservoir during culture, when the rate of algae foreign to the culture resulting from the germination of spores brought by seawater becomes uncomfortable, an aqueous oxidizing solution containing a bipochloride alkali.

-9The amount of NaOCl depends on the characteristics of the reservoir and the quartz of algae present, and the specialist will have to determine it anyway.

A rapid treatment can be carried out, during which the oxidant is destroyed after a few minutes by the addition of a reducer, such as a thiosulfate or an alkali hydrogen sulfite or a simpler treatment in which the oxidaxt is left. .and eliminate itself spontaneously; It is evident that in the second case, its initial concentration should be weaker, 15 to 25 Z less.

In a reservoir with an elliptical shape of about 980 m, in which the large exxus and 7.2 times the small axis, 40 cm deep and comprising two obstacles of 1 m and two obstacles of 2 m in length, arranged as indicated in figure 1, re2 253 g / m in dry weight of red algae of the species Chondrus crispus were harvested in 4 weeks, from which carrageenan is extracted.

By way of comparison, in a small round reservoir of 3 m in diameter, braceleted by a strong bubbling of air, it was collected simultaneously with the same enriched marine environment, only at 234 g / m of algae and this for an operating cost frankly superior, being given the air bracelet.

Claims (8)

1 . - Macroscopic algae culture tank fed by water, characterized by having a more or less flattened elliptical crown shape defined between an outer wall and a central core comprising at least one radially arranged wheel with blades, and at least 2 groups of obstacles in which one is located on the axis of the central core and the other downstream of the wheels with blades, which) makes the chain an angle between 90 ° and 160 ° and in which the width is, at most, equal to half the length of the liquid stream. 2 . Reservoir according to claim 1, characterized in that the central core (12) is reduced to a plane * 3. Reservoir according to any one of claims 1 and 2, characterized in that the obstacles are vertical or inclined walls that level the upper level of the liquid. a ~ 4. - Process for obtaining Chondrus crispus, characterized by the cultivation of algae in a reservoir according to one of claims 1 to 3, fed by seawater and supplemented by sources of carbon, nitrogen and phosphorus. The - 5. Process according to claim 4, characterized in that the carbon source is carbon dioxide, a carbonate or a carboxylic acid. 11. A process according to claim 4 or 5, characterized in that the pH of the medium is maintained between 8 and 9. 7. Process according to claim 6, characterized in that the pH of the medium is maintained between 8.5 and 8.8 by the occasional addition of a mineral acid during important periods of photosynthesis. 8. Process according to one of claims 4 to 7, characterized in that it also comprises the addition of an alkaline hydrochloride in order to eliminate foreign algae. The 9. Process according to claim 8, characterized in that the hypochloride access is destroyed by the addition of a thiosulfate or an alkaline hydrogen sulfide. Lisbon, 14 May 1990