WO2010140037A1 - Procédé de séchage d'une biomasse algale - Google Patents

Procédé de séchage d'une biomasse algale Download PDF

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Publication number
WO2010140037A1
WO2010140037A1 PCT/IB2010/001230 IB2010001230W WO2010140037A1 WO 2010140037 A1 WO2010140037 A1 WO 2010140037A1 IB 2010001230 W IB2010001230 W IB 2010001230W WO 2010140037 A1 WO2010140037 A1 WO 2010140037A1
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Prior art keywords
algal biomass
process according
aqueous suspension
layer
ranging
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PCT/IB2010/001230
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English (en)
Inventor
Gianni Pandolfi
Roberta Miglio
Lino Carnelli
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Eni S.P.A.
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Publication of WO2010140037A1 publication Critical patent/WO2010140037A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
    • C12N1/005—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor after treatment of microbial biomass not covered by C12N1/02 - C12N1/08
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
    • C12N1/12—Unicellular algae; Culture media therefor
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
    • C12P7/00—Preparation of oxygen-containing organic compounds
    • C12P7/64—Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
    • C12P7/6436—Fatty acid esters
    • C12P7/6445—Glycerides
    • C12P7/6463—Glycerides obtained from glyceride producing microorganisms, e.g. single cell oil
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00—Technologies for the production of fuel of non-fossil origin
    • Y02E50/10—Biofuels, e.g. bio-diesel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/133—Renewable energy sources, e.g. sunlight

Definitions

  • the present invention relates to a process for the drying of algal biomass.
  • the present invention relates to a process for the drying of algal biomass, which comprises depositing a layer of a concentrated aqueous suspension of algal biomass on a hydrophobic surface and putting said layer in contact with hot air.
  • the dried algal biomass obtained through the above process can be advantageously used in the production of lipids.
  • Said lipids in turn, can be used in the production of biodiesel or green diesel.
  • said dried algal biomass can be advantageously used for the production of bio-oil or bio-crude.
  • said dried algal biomass can be advantageously used for the production of energy through thermal treatments such as, for example, combustion or gasification.
  • Algae in particular microalgae, are currently cultivated for the production of valuable compounds such as, for example, poly-unsaturated fatty acids [for example, eicosapentaenoic acid (EPA) , docosahexaenoic acid (DHA) , and the like] , vitamins (for example, ⁇ - carotene, and the like) and gelling agents, which are included in the nutritional, pharmaceutical and cosmetic fields.
  • poly-unsaturated fatty acids for example, eicosapentaenoic acid (EPA) , docosahexaenoic acid (DHA) , and the like
  • vitamins for example, ⁇ - carotene, and the like
  • gelling agents which are included in the nutritional, pharmaceutical and cosmetic fields.
  • microalgae for the above field is characterized by rather limited production capacities (in the order of hundreds-thousands of tons per year) and by a high added value of the compounds obtained (hundreds-thousands of euro per kilogram) . This is why complex and expensive production systems, particularly with respect to the concentration and drying of the biomass and to the extraction of products of interest, which must satisfy the strict regulations of the sanitary and nutritional type, typical of the above-mentioned fields, can be tolerated.
  • Molina Grima et al . describe the recovery of algal biomass and metabolites in the following article "Recovery of microalgal biomass and metabolites: process options and economics", published in "Biotechnology Advances” (2003), 20, pg. 491-515. In said article, it is specified the necessity of treating the algal biomass recovered, for example, by centrifugation, rapidly, as said biomass can be seriously damaged in a few hours in hot climates. In order to keep said algal biomass for longer periods of time, it is therefore useful to subject said biomass to drying. Suggested drying methods include: spray drying, drum drying, freeze drying, and sun drying.
  • United States Patent US 5,539,133 describes a method for obtaining lipids with a high quantity of poly-unsaturated fatty acids having from 20 to 22 carbon atoms through the extraction of a raw material of an animal or vegetable origin, said raw material having a water content of from 5% by weight to 50% by weight and a particles size of from 0.01 mm to 50 mm, said extraction being carried out using an organic solvent, preferably miscible with water (e.g., ethanol) , or through liquefied compressed gas (e.g., carbon dioxide, propane, or blends thereof) .
  • an organic solvent preferably miscible with water (e.g., ethanol)
  • liquefied compressed gas e.g., carbon dioxide, propane, or blends thereof
  • unicellular algae microalgae
  • macroalgae belonging to the family of red, brown o green algae are also indicated, said algae being previously dried.
  • partially dried products (“algae flour”) based on red or brown algae available on the market, can be used as raw material .
  • Said polyunsaturated fatty acids such as, for example, docosahexaenoic acid (DHA) , arachidonic acid, are particularly used in the food industry.
  • DHA docosahexaenoic acid
  • arachidonic acid are particularly used in the food industry.
  • Miao X. et al describe the production of biodiesel from algae in the following article: "Biodiesel production from heterotrophic microalgal oil” , published in “Bioresource Technology” (2006), 97, pg. 841-846.
  • algae of the species Chorella protothecoides grown under heterotrophic conditions, are collected by centrifugation, washed with distilled water and subsequently dried in a freeze drier.
  • the freeze-dried algae are subsequently pulverized in a mortar and subjected to extraction with hexane in order to extract the oil.
  • the extracted oil is subsequently .subjected to acid transesterification in the presence of methanol and sulphuric acid as transesterification catalyst in order to obtain biodiesel.
  • biodiesel from algae is also described by Hossain S. et . al . in the following article: "Biodiesel Fuel Production from Algae as Renewable Energy” , published in "American Journal of Biochemistry and Biotechnology” (2008), 4 (3), pg. 250- 254.
  • algae of the species Oedogonium and Spirogyra after being ground and chopped as much as possible, are dried in a thermostatic oven at 80 0 C, for 20 minutes, in order to eliminate the water.
  • a solution of hexane and ether is mixed with the dried algae to extract the oil.
  • the oil extracted is recovered by means of evaporation, under vacuum, from said hexane and ether solution.
  • the transesterification reaction of the oil thus obtained is carried out in the presence of a mixture of sodium hydroxide as transesterification catalyst and methanol (basic transesterification) .
  • United States Patent Application US 2006/0275863 describes a method for preserving the xanthophylls in algal cells, comprising: growing algal cells containing xanthophylls and subsequently recovering said algal cells; and drying the algal cells in order to obtain algal cells having a humidity content lower than or equal to 3% by weight. No particular limitations are indicated with respect to the drying process .
  • said algal cells can be dried through drum drying, hot air drying, freeze drying, spray drying. Spray drying is preferred and the temperature of the air at the outlet of the equipment used for said spray drying is regulated at 125 0 C or higher.
  • the above processes can have various critical aspects, however.
  • the mixture air/algal biomass powder which is formed can be explosive under certain conditions (temperature, dimension and concentration of the powder, residual humidity, etc.) which imposes particular restrictions for the spray drying equipment, with consequent economical expenses .
  • the algal biomass powder obtained by spray drying generally has fine dimensions and can therefore be potentially inhalable and harmful for the respiratory system of the operators. Consequently the installation of suitable filters is generally required in order not to harm the health of the operators with consequent additional economical expenses .
  • freeze drying process is a drying process capable of giving high-quality dried algal biomass, it is extremely onerous in energy and economic terms.
  • the Applicant has now found that the drying of algal biomass can be advantageously obtained by depositing a layer of a concentrated aqueous suspension of algal biomass on a hydrophobic surface and putting said layer in contact with hot air. Said process allows dried algal biomass to be obtained avoiding the formation of algal biomass powder and, consequently, the optional problems mentioned above. This process also allows dried algal biomass to be obtained having a high quality, equal to that obtained by means of freeze drying, but avoiding the costs of the freeze drying process .
  • this process allows to avoid the use of heated water and, consequently to simplify the drying process also with respect to the process known as Refractance Window ® described above, with a consequent economical advantage.
  • An object of the present invention therefore relates to a process for the drying of algal biomass, comprising: producing an aqueous suspension of algal biomass; - concentrating said aqueous suspension of algal , biomass in order to obtain a concentrated aqueous suspension of algal biomass; depositing a layer of said concentrated aqueous suspension of algal biomass on a hydrophobic surface, in order to obtain a layer having a thickness lower than or equal to 1 cm, preferably ranging from 0.2 to 0.6 cm; putting this layer in contact with hot air, said hot air being at a temperature ranging from 4O 0 C to
  • HO 0 C preferably ranging from 60 0 C to 9O 0 C in order to obtain a layer of dried algal biomass.
  • hydrophobic surface means a surface on which a drop of water forms a contact angle higher than 90° .
  • the production of said aqueous algal biomass can derive from the cultivation of algae, preferably unicellular (microalgae) , carried out in wastewater coming from industrial and/or civil wastewaters.
  • the algal cultivation metabolizes the substances containing nitrogen and/or phosphorous contained therein, contributing to their purification.
  • CO 2 necessary for algal growth that contained in industrial combustion gases (refineries, thermoelectric plants, hydrogen generation plants, etc.), can be used.
  • the production of said aqueous suspension of algal biomass can derive from the cultivation of algae, preferably unicellular (microalgae) , carried out in sea water.
  • the cultivation of said algae can be carried out under photo-autotrophic conditions, heterotrophic conditions, or under mixotrophic conditions.
  • the concentration of said aqueous suspension of algal biomass can be carried out through various processes such as, for example: gravitational separation by means of sedimentation and/or thickening apparatuses, typically used in the water treatment plants; flotation; - gravimetric separation by means of cyclones or spirals ; centrifugation,- filtration by means of membranes for ultra- or micro- filtration, or vacuum filtration; - treatment by means of filter presses or belt presses .
  • said aqueous suspension of algal biomass can be subjected to flocculation.
  • Said flocculation can be carried out by means of various processes, such as, for example : bio-flocculation (for example, by cultivating algae in culture mediums having a low nitrogen concentration) ; addition of at least one flocculating agent to said aqueous suspension of algal biomass.
  • said flocculation can be carried out by the addition of at least one flocculating agent.
  • Said flocculating agent is preferably selected from: metal salts such as, for example, iron chloride, aluminium sulphate, iron sulphate; cationic polyelectrolytes such as, for example, polyethylene imines, polyacrylamides, chitosane; or mixtures thereof.
  • metal salts such as, for example, iron chloride, aluminium sulphate, iron sulphate
  • cationic polyelectrolytes such as, for example, polyethylene imines, polyacrylamides, chitosane; or mixtures thereof.
  • the concentration of algal strains of fresh water can be particularly facilitated by the use of cationic polyelectrolytes, preferably polyacrylamides, adopted in a quantity of 2 ppm - 10 ppm (passage of the algal concentration from 0.2 g/1 to 30 g/1 - 40 g/1 in a few hours) .
  • said concentrated aqueous suspension of algal biomass can have a concentration of dry algal biomass ranging from 5% by weight to 25% by weight, more preferably from 8% by weight to 20% by weight, with respect to the total weight of the concentrated aqueous suspension of algal biomass .
  • said concentrated aqueous suspension of algal biomass can have a concentration of water ranging from 75% by weight to 95% by weight, more preferably ranging from 80% by weight to 92% by weight, with respect to the total weight of the concentrated aqueous suspension of algal biomass .
  • the water released from the concentration of said aqueous suspension of algal biomass can be recovered in a large quantity and re-used in the above-mentioned process as water in the production of said aqueous suspension of algal biomass (i.e. as cultivation water of the algae) .
  • said hydrophobic surface can include at least one hydrophobic polymer having a melting point higher than or equal to HO 0 C, preferably ranging from 120 0 C to 380 0 C.
  • said hydrophobic polymer can be selected from: polyolefins, such as, for example, polypropylene, polyethylene, ; polyesters, such as, for example, polyethylene terephthalate (e.g. Mylar of DuPont) ; halogenated polymers, such as, for example, polyvinylchloride, polytetrafluoroethylene (e.g. Teflon 0 of DuPont); polystyrenes; polysulfones , such as, for example, polyethersulfone; or mixtures thereof.
  • polypropylene, polyethylene, polyethylene terephthalate (e.g., Mylar* of DuPont), or mixtures thereof, are preferred.
  • said hydrophobic surface can have a thickness ranging from 0.2 mm to 5 mm, preferably ranging from 0.5 mm to 3 mm. Said hydrophobic surface can be smooth or wrinkled.
  • a conveyor belt In order to automate the depositing operations of said concentrated aqueous suspension of algal biomass on said hydrophobic surface, a conveyor belt can be advantageously used.
  • said hydrophobic surface can be a conveyor belt .
  • said hydrophobic surface can be applied on a conveyor belt.
  • said conveyor belt can be of polymeric material such as, for example, polyamides (e.g., nylon), rubbers, or mixtures thereof.
  • Said conveyor belt can operate batchwise, when the conveyor belt is kept in movement both during the depositing operations of the concentrated aqueous suspension of algal biomass on said conveyor belt and during the discharge of the dried algal biomass from said conveyor belt and is stopped during the drying operations of the algal biomass; or in continuous, when the conveyor belt is kept running during the whole process .
  • said conveyor belt can move at a rate ranging from 0.1 m/min to 130 m/tnin, preferably ranging from:
  • said hot air can be heated using solar energy, or waste vapours coming from other processings.
  • solar energy is preferred. It should be noted that if waste vapours are used, it is advantageous to adopt a heat exchanger.
  • said layer of concentrated suspension of algal biomass can be put in contact with hot air for a time ranging from 30 minutes to 10 hours; preferably from 1 hour to 6 hours.
  • said hot air can be anhydrous air.
  • anhydrous air refers to air having at room temperature (i.e. 25°C) , a relative humidity content lower than or equal to 70%, preferably ranging from 0% to 50%.
  • said hydrophobic surface can be placed a metal grid, or a net of polymeric material such as, for example, polyvinylchloride, said grid or net preferably with meshes having a dimension lower than 2 cm x 2 cm (h x
  • said grid, net or sheet of paper can be placed at a distance, with respect to said hydrophobic surface, lower than or equal to 5 cm, preferably ranging from 1 to 4 cm.
  • a further object of the present invention therefore relates to a process for the drying of algal biomass inside a substantially closed structure, said substantially closed structure including at least one hydrophobic surface, comprising: producing an aqueous suspension of algal biomass; concentrating said aqueous suspension of algal biomass in order to obtain a concentrated aqueous suspension of algal biomass; depositing a layer of said concentrated aqueous suspension of algal biomass on a hydrophobic surface, in order to obtain a layer having a thickness lower than or equal to 1 cm, preferably ranging from 0.2 cm to 0.6 cm; putting this layer in contact with hot air, said hot air being at a temperature ranging from 40 0 C to 110 0 C, preferably ranging from 60 0 C to 90 0 C in order to obtain a layer of dried algal biomass .
  • substantially closed structure means a structure equipped with a cover, which can optionally be opened, wherein the air enters from one side and exits from the opposite side.
  • said substantially closed structure can be equipped with slanting side panels (hut covering) , or by at least one upper panel (flat covering) and at least one side panel.
  • Said panels can be selected, for example, from glass; plastic materials such as, for example, plexiglass, polyacrylates, polycarbonates, polystyrene, polyolefins (e.g.
  • polyethylene, polypropylene) ; composite materials such as, for example, polyolefins reinforced with glass fibres; said plastic materials and/or said composite materials preferably being stabilized to UV rays by the addition of UV stabilizing agents, such as, for example, benzophenones, benzotriazoles, sterically hindered amines (HALS), or mixtures thereof.
  • UV stabilizing agents such as, for example, benzophenones, benzotriazoles, sterically hindered amines (HALS), or mixtures thereof.
  • said panels are made of UV-stabilized polyethylene.
  • said hydrophobic surface can be a conveyor belt.
  • said hydrophobic surface can be applied on a conveyor belt.
  • said conveyor belt can be made of polymeric materials, such as, for example, polyamides (e.g., nylon), rubbers, or mixtures thereof .
  • said conveyor belt can move at a rate ranging from 0.1 m/min to 130 m/min, preferably ranging from:
  • the movement of said hot air inside said substantially closed structure can be carried out by means of a chimney, or by means of a fan.
  • said hot air can move inside said substantially closed structure at a flow-rate ranging from 0.2 m/min to 10 m/min, preferably ranging from 0.3 m/min to 4 m/min.
  • said hot air can move inside said substantially closed structure at a flow-rate ranging from 15 Nm 3 / n to 250 Nm 3 /h, preferably from 18 Nm 3 /h. and 240 Nm 3 /h
  • said layer of dried algal biomass can generally have a thickness lower than or equal to 1/10 with respect to the thickness of the layer of the concentrated aqueous suspension of algal biomass deposited on said hydrophobic surface.
  • said layer of dried algal biomass can have a thickness lower than or equal to 0.1 cm, preferably ranging from 0.02 cm to 0.06 cm.
  • said layer of dried algal biomass can have a residual humidity content lower than or equal to 5% by weight, preferably ranging from 0.5% to 3% by weight, with respect to the total weight of said layer of dried algal biomass .
  • the aqueous suspension of algal biomass is produced through the cultivation of microalgae, carried out in wastewater coming from industrial discharges, or in sea water.
  • the production of microalgae for example, can be suitably carried out by combining cultivation systems such as photoreactors and open ponds .
  • the aqueous suspension of algal biomass thus obtained is concentrated by gravitational separation, preferably in the presence of a flocculating agent, obtaining a concentrated aqueous suspension of algal biomass (2) .
  • the water released from the concentration of the aqueous suspension of algal biomass can be mostly recovered and re-used in the above process as water in the production of said aqueous suspension of algal biomass (i.e. as cultivation water of algae) (not represented in Figure 1) .
  • the concentred aqueous suspension of algal biomass (2) is fed through a feeding pump (not represented in Figure 1) to a hopper (3) situated inside a substantially closed structure (1) , said substantially- closed structure comprising a frame (6) , sloping side panels (hut covering) (7) (the sloping is not shown in Figure 1) and supports (8) .
  • Said panels are preferably made of polyethylene stabilized to ultraviolet rays .
  • Said panels can be opened (not represented in the figure 1) .
  • a concentrated aqueous suspension of algal biomass, having a concentration of dry algal biomass preferably ranging from 8% by weight to 20% by weight with respect to the total weight of the concentrated aqueous suspension of algal biomass, is then fed to said
  • the concentrated aqueous suspension of algal biomass leaving the hopper is deposited on a conveyor belt, preferably of Mylar* of DuPont, in order to obtain a layer of concentrated aqueous suspension of algal biomass having a thickness preferably ranging from 0.2 cm to 0.6 cm.
  • Air is introduced into this substantially closed structure (1) , in countercurrent with respect to the conveyor belt (4) , by means of the fan (13) through the duct (14) .
  • the air can be heated with the use of solar energy or, as alternatively, it can be preheated using waste vapours coming from other processing, through the heat exchanger (12) .
  • said fan (13) can be activated using the energy [represented with the dashed line (17)] provided by a solar panel (16) .
  • Said solar panel (16) can include a photovoltaic device capable of collecting and converting the solar radiations into electric energy.
  • the air is heated to a temperature ranging from 6O 0 C to 90 0 C, using solar energy.
  • the fan (13) can be stopped, and the air circulation inside said substantially closed structure (1) , can be allowed by the presence of a chimney (5) .
  • Said chimney (5) also serves for eliminating the water vapour deriving from the drying of the concentrated aqueous suspension of algal biomass. Said water vapour, in fact, leaves the chimney (5) as humid air.
  • a metal net (15) is positioned above said conveyor belt (4), said net preferably having meshes with dimensions lower than 2 cm x 2 cm (h x 1) , at a distance preferably ranging from 1 cm to 4 cm with respect to said conveyor belt (4) .
  • a thin layer of dried algal biomass is obtained, having a thickness preferably ranging from 0.02 cm to 0.06 cm, which is detached from the conveyor belt (4) either naturally, or by means of a scraper (not represented in Figure 1) which can be situated at the end of the conveyor belt (4) , on the opposite side with respect to the hopper (3), fragmenting into pieces ("leaves") .
  • Said pieces ("leaves") are subsequently collected in a discharge hopper (9) .
  • Said pieces (“leaves”) can be directly sent for further treatment, such as, for example, lipid extraction, biodiesel or green diesel production, bio- oil or of "bio-crude” production, energy production, or they can be collected into sacks (not represented in Figure 1) and sent to storage.
  • Said sacks can be stored for long periods (in the order of months) .
  • the dried algal biomass obtained according to the process of the present invention can be subjected to further treatment.
  • Said dried algal biomass for example, can be subjected to lipid extraction.
  • Said extraction can be carried out by means of processes known in the art, such as, for example, mechanical extraction; extraction in the presence of organic solvents (for example, C 6 -C 8 hydrocarbons, alcohols or mixtures thereof, etc.) operating in liquid phase, or operating under supercritical conditions (for example, in the presence of carbon dioxide, propane, or mixtures thereof, etc.) .
  • organic solvents for example, C 6 -C 8 hydrocarbons, alcohols or mixtures thereof, etc.
  • supercritical conditions for example, in the presence of carbon dioxide, propane, or mixtures thereof, etc.
  • the extracted lipids can be subjected to transesterification in the presence of an alcohol having from 1 to 4 carbon atoms, preferably methanol, ethanol, and a catalyst, preferably an acid catalyst, in order to produce glycerol and alkyl esters, in particular methyl esters or ethyl esters (biodiesel) .
  • an alcohol having from 1 to 4 carbon atoms preferably methanol, ethanol, and a catalyst, preferably an acid catalyst, in order to produce glycerol and alkyl esters, in particular methyl esters or ethyl esters (biodiesel) .
  • the extracted lipid can be subjected to hydrogenation/deoxygenation in the presence of hydrogen and a catalyst for the production of green diesel.
  • Hydrogenation/deoxygenation processes are known in the art and are described, for example, in European patent application EP 1,728,844.
  • said dried algal biomass can be used for the production of bio-oil or bio-crude which can be carried out by means of thermal treatments such as, for example, liquefaction or pyrolysis.
  • said dried algal biomass can be used in the production of energy which can be carried out by means of thermal treatments such as, for example, combustion or gasification.
  • An aqueous suspension of algal biomass was used for this purpose, obtained from the algal strain of Scenedesmus sp. grown in a culture medium M4N indicated in literature for the cultivation of microalgae .
  • the aqueous suspension was subjected to determination of the concentration of algal bioraass which proved to be equal to 0.92 g/1.
  • aqueous suspension of algal biomass was then centrifuged in a disk centrifuge (Alfa Laval) obtaining an aqueous suspension of algal biomass having a concentration of dry algal biomass equal to 10 g/litre.
  • aqueous suspension of algal biomass was subsequently subjected again to centrifugation in a rotor centrifuge (Sorvall) until a concentrated aqueous suspension of algal biomass was obtained, having a concentration of dry algal biomass equal to 18% by weight with respect to the total weight of said concentrated aqueous suspension of algal biomass.
  • a sample of said concentrated aqueous suspension of algal biomass was poured onto a tray having dimensions equal to 50 cm x 50 cm covered by a polyester film
  • the tray was then covered by a metal grid having meshes with dimensions equal to 0.8 cm x 0.8 cm (h x 1) positioned at a distance of 2 cm with respect to said layer of concentrated aqueous suspension of algal biomass and was placed in a ventilated oven under the following operative conditions : air temperature 65°C; residence time: 4 hrs; air flow-rate: 20 Nm 3 /h..
  • the tray was extracted from the oven: the layer of dried algal biomass was in the form of "leaves" detached from the polyester film.
  • sample D A sample of algal biomass, dried as described in Example 1, was subjected to solvent extraction (sample D •
  • a sample of algal biomass obtained as described in Example 1 but dried through freeze drying, at -5O 0 C, for about 20 hrs, was subjected to solvent extraction (sample 2) .
  • both samples were subjected to extraction in a Soxhlet apparatus, using n-octane as extraction solvent, operating under the following conditions : n-octane/dried algal biomass ratio: 25 w/w,- temperature: 125 0 C; - time: 20 cycles of 15 minutes each.
  • Said concentrated aqueous suspension was diluted with deionized water in order to obtain a concentration of algal biomass equal to 0.200 g/1.
  • Said aqueous suspension of algal biomass was placed in a settler and left to settle for 2 hrs, after the addition, under strong stirring (500 rpm) , of 10 mg/1 of polyacrylamide .
  • the solid phase comprising a concentrated aqueous suspension of algal biomass having a concentration of dried algal biomass equal to 33 g/litre, was collected from the bottom of the settler.
  • said concentrated aqueous suspension of algal biomass was subjected to vacuum filtration and a concentrated aqueous suspension of algal biomass was obtained having a concentration of dried algal biomass equal to 10% by weight with respect to- the total weight of the concentrated aqueous suspension of algal biomass .
  • a sample of said concentrated aqueous suspension of algal biomass was poured onto a tray having dimensions equal to 50 cm x 50 cm, covered by a film of corrugated polypropylene, in order to obtain a layer of concentrated aqueous suspension of algal biomass having a thickness of 0.3 cm.
  • the tray was then covered with a metal grid having meshes with dimensions equal to 0.8 cm x 0.8 cm (h x 1) positioned at a distance of 2 cm with respect to said layer of aqueous suspension of algal biomass and was placed in a ventilated oven, under the following operative conditions: air temperature 75 0 C; residence time: 2 hrs ; At the end of the drying, the tray was extracted from the oven: the layer of dried algal biomass was in the form of "leaves" detached from the polyester film. Said "leaves” were collected and subjected to thermogravimetric analysis, with an operating temperature of 120 0 C, in order to determine the content of residual humidity which proved to be lower than 3% by weight with respect to the total weight of said layer of dried algal biomass.

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  • Tropical Medicine & Parasitology (AREA)
  • Biomedical Technology (AREA)
  • Virology (AREA)
  • Botany (AREA)
  • Sustainable Development (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Micro-Organisms Or Cultivation Processes Thereof (AREA)
  • Beans For Foods Or Fodder (AREA)
  • Preparation Of Compounds By Using Micro-Organisms (AREA)

Abstract

La présente invention concerne un procédé de séchage d'une biomasse algale, comprenant les étapes consistant à : - produire une suspension aqueuse d'une biomasse algale ; concentrer ladite suspension aqueuse de biomasse algale afin d'obtenir une suspension aqueuse concentrée de biomasse algale ; déposer une couche de ladite suspension aqueuse concentrée de biomasse algale sur une surface hydrophobe, afin d'obtenir une couche ayant une épaisseur inférieure ou égale à 1 cm, allant de préférence de 0,2 à 0,6 cm,- mettre en contact cette couche avec de l'air chaud, ledit air chaud étant à une température allant de 40 °C à 110 °C, de préférence allant de 60 °C à 90 °C afin d'obtenir une couche d'une biomasse algale sèche. La biomasse algale sèche obtenue par le biais du procédé mentionné ci-dessus peut être utilisée de manière avantageuse dans la production de lipides. Lesdits lipides peuvent être utilisés, à leur tour, dans la production de biodiesel ou de diesel vert. En variante, ladite biomasse algale sèche peut être utilisée de manière avantageuse dans la production de biocarburant ou de produit biologique brut. En variante, ladite biomasse algale sèche peut être utilisée de manière avantageuse dans la production d'énergie par des traitements thermiques tels que, par exemple, la combustion ou la gazéification.
PCT/IB2010/001230 2009-06-05 2010-05-18 Procédé de séchage d'une biomasse algale WO2010140037A1 (fr)

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US20170211038A1 (en) * 2016-01-26 2017-07-27 Jiangsu Provincial Academy Of Environmental Science Method for deep dehydration and desiccation of cyanobacteria
US10160673B2 (en) 2011-09-28 2018-12-25 General Electric Company Method for flocculating algae using polymers including tannin
US10488110B2 (en) 2015-09-14 2019-11-26 Ecoduna Ag Belt dryer and method for dewatering microalgae
FR3090834A1 (fr) * 2018-12-24 2020-06-26 Algeanova Dispositif de sechage

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CN110934220A (zh) * 2020-01-08 2020-03-31 济南大学 一种酥脆营养冰淇淋及其制备方法

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10160673B2 (en) 2011-09-28 2018-12-25 General Electric Company Method for flocculating algae using polymers including tannin
CN102604837A (zh) * 2012-04-16 2012-07-25 盐城工学院 一种微藻细胞絮凝采收的工艺
US10488110B2 (en) 2015-09-14 2019-11-26 Ecoduna Ag Belt dryer and method for dewatering microalgae
US20170211038A1 (en) * 2016-01-26 2017-07-27 Jiangsu Provincial Academy Of Environmental Science Method for deep dehydration and desiccation of cyanobacteria
US10457910B2 (en) * 2016-01-26 2019-10-29 Jiangsu Provincial Academy Of Environmental Science Method for deep dehydration and desiccation of cyanobacteria
FR3090834A1 (fr) * 2018-12-24 2020-06-26 Algeanova Dispositif de sechage

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IT1394412B1 (it) 2012-06-15

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