Mass algal culture system

Claim 2

A gas lift pump mechanism for circulating a liquid medium containing an algal culture and for facilitating the separation of suspended substances from said liquid medium comprising: a substantially vertical stand pipe having a liquid medium inlet and a medium outlet located above said inlet; first gas inlet means for introducing a sufficient volume of gas into liquid medium inside said pipe to cause said medium to rise therein; and second gas inlet means, separate from said first gas inlet means, for introducing a stream of minute gas bubbles into said liquid medium inside said pipe which bubbles adhere to suspended substances in said liquid medium and increase the buoyancy of said substances.

Claim 3

The pump mechanism of claim 1 further comprising heat exchange means associated with said vertical stand pipe to adjust the temperature of liquid medium as it moves through said pipe.

Claim 4

The pump mechanism of claim 1 wherein said first and second gas inlet means are located at different elevations inside said stand pipe.

Claim 5

The pump mechanism of claim 3 wherein said first gas inlet means is located above said second gas inlet means.

Claim 6

The pump mechanism of claim 1 further comprising: means for supplying a stream of air to said first gas inlet means and means for supplying a stream of CO 2 to said second gas inlet means.

Claim 7

A process for separately removing impurity substances and suspended algal cells from a continuously recirculating liquid algal culture medium which contains said impurity substances and said cells, said process comprising: bringing algal cells and impurity substances carried in a continuously recirculating liquid medium into contact with gas bubbles to increase the buoyancy of said cells and of said impurity substances; moving said liquid medium through a trough at such a rate that the gas bubbles carry relatively small and light impurity substances to the surface of said medium and that said algal cells, which are relatively large and heavier, and which have adsorbed said gas bubbles but are carried downstream by the current and do not rise to said surface; removing said light impurity substances from said surface at a first location along said trough; at a second location downstream of said first location, reducing the rate at which said liquid medium moves through said trough so that algal cells with adsorbed gas bubbles rise to said surface at said second location; and removing a fraction of the algal cells circulating in said medium from said surface at said second location.

Claim 8

A process for separately removing impurity substances and suspended algal cells from a continuously recirculating liquid algal culture medium which contains said impurity substances and said cells, said process comprising: bringing algal cells and impurity substances carried in a continuously recirculating liquid medium into contact with gas bubbles to increase the buoyancy of said cells and of said impurity substances; moving said liquid medium through a trough at such a rate that the gas bubbles carry relatively small and light impurity substances to the surface of said medium and that said algal cells, which are relatively large and heavier, and which have adsorbed said gas bubbles but are carried downstream by the current and do not rise to said surface; removing said light impurity substances from said surface at a first location along said trough; at a second location downstream of said first location, reducing the rate at which said liquid medium moves through said trough so that algal cells with adsorbed gas bubbles rise to said surface at said second location; and removing a fraction of the algal cells circulating in said medium from said surface at said second location.

Claim 9

The process of claim 6 wherein the impurity substances comprise dissolved organic substances which, when contacted with gas bubbles, form a foam that rises to the surface of the medium.

Claim 12

A system as defined in claim 8 and comprising means for reducing the rate of flow of said medium adjacent said harvesting means to facilitate rise of said algal cells.

Claim 13

A system as defiend in claim 8 wherein said harvesting means is located at the opposite end of said trough from said gas lift.

Claim 14

A system as defined in claim 10 wherein said discharge means for said medium is connected to said inlet of said gas lift to recirculate said medium.

Claim 17

A continuous process for mass culture of a selected species of marine microalgae comprising: filling an algal culture container with a liquid culture medium precursor comprising sea water in which is dissolved a mixture of nutrient salts which consists essentially of HNO 3 , H 3 PO 4 , KCl, Na 2 EDTA, and trace amounts of FeCl 3 .6H 2 O, (NH 4 ) 6 Mo 7 O 24 .4H 2 O, H 3 BO 3 , ZnCl 2 , CuCl 2 .2H 2 O and MnCl 2 .4H 2 O; adding an amount of KOH to said precursor sufficient to adjust its pH to a level which facilitates a desired reproduction and growth pattern for a selected algal species and to complete said precursor's nutrient content whereby a liquid medium suitable for the growth of said algal species is formed; innoculating said medium with a culture of said algal species; circulating said innoculated medium through an open trough of shallow depth by withdrawing medium from one end of the trough and replacing it in the other end; maintaining the temperature of said innoculated medium within a range conducive to the growth and reproduction of said algal species; channeling the flow of innoculated medium from said one end of said trough through the vertical stand pipe of a gas lift pump mechanism equipped for the introduction of minute gas bubbles comprising substantial amounts of carbon dioxide into liquid medium passing therethrough to: a. accomplish said circulating; and b. bring organic substances and the cells of said algal culture into contact with a stream of minute gas bubbles which are adsorbed thereon to increase the buoyancy of said organic substances and said microalgae so that they tend to rise to the surface of medium in the trough; moving liquid medium containing dissolved organic substances and algal cells with adsorbed minute gas bubbles through said trough at a rate such that the relatively small and light organic substances with adsorbed gas bubbles rise to the surface of said medium and the relatively large and heavier algal cells with adsorbed gas bubbles are carried by the current and not allowed to rise to said surface; skimming said organic substances from said surface; subsequently slowing the rate at which said liquid medium moves through said trough so that algal cells with adsorbed gas bubbles rise to said surface; skimming algal cells from said surface; exposing the surface of medium in the trough to sunlight which has been filtered sufficiently to facilitate the photosynthesis of the microalgae by removing light wavelengths which inhibit algal growth and reproduction, while transmitting photosynthetically active wavelengths; alternately positioning individual cells of the algae in portions of said medium distant and adjacent to said medium surface and thus alternately exposing the cells to maximum light intensity when adjacent to said surface and decreasing light intensity when progressively more distant from said surface; replenishing nutrient salts in the medium as they are consumed by said microalgae so that sufficient nutrients are maintained in said medium to sustain desired algal growth and reproduction rates; and injecting CO 2 into said medium in sufficient quantity to maintain a desired alkalinity and nutrient carbon content in said medium.

Claim 18

A continuous process for mass culture of a selected species of marine microalgae comprising: filling an algal culture container with a liquid culture medium precursor comprising sea water in which is dissolved a mixture of nutrient salts which consists essentially of HNO 3 , H 3 PO 4 , KCl, Na 2 EDTA, and trace amounts of FeCl 3 .6H 2 O, (NH 4 ) 6 Mo 7 O 24 .4H 2 O, H 3 BO 3 , ZnCl 2 , CuCl 2 .2H 2 O and MnCl 2 .4H 2 O; adding an amount of KOH to said precursor sufficient to adjust its pH to a level which facilitates a desired reproduction and growth pattern for a selected algal species and to complete said precursor's nutrient content whereby a liquid medium suitable for the growth of said algal species is formed; innoculating said medium with a culture of said algal species; circulating said innoculated medium through an open trough of shallow depth by withdrawing medium from one end of the trough and replacing it in the other end; maintaining the temperature of said innoculated medium within a range conducive to the growth and reproduction of said algal species; channeling the flow of innoculated medium from said one end of said trough through the vertical stand pipe of a gas lift pump mechanism equipped for the introduction of minute gas bubbles comprising substantial amounts of carbon dioxide into liquid medium passing therethrough to: a. accomplish said circulating; and b. bring organic substances and the cells of said algal culture into contact with a stream of minute gas bubbles which are adsorbed thereon to increase the buoyancy of said organic substances and said microalgae so that they tend to rise to the surface of medium in the trough; moving liquid medium containing dissolved organic substances and algal cells with adsorbed minute gas bubbles through said trough at a rate such that the relatively small and light organic substances with adsorbed gas bubbles rise to the surface of said medium and the relatively large and heavier algal cells with adsorbed gas bubbles are carried by the current and not allowed to rise to said surface; skimming said organic substances from said surface; subsequently slowing the rate at which said liquid medium moves through said trough so that algal cells with adsorbed gas bubbles rise to said surface; skimming algal cells from said surface; exposing the surface of medium in the trough to sunlight which has been filtered sufficiently to facilitate the photosynthesis of the microalgae by removing light wavelengths which inhibit algal growth and reproduction, while transmitting photosynthetically active wavelengths; alternately positioning individual cells of the algae in portions of said medium distant and adjacent to said medium surface and thus alternately exposing the cells to maximum light intensity when adjacent to said surface and decreasing light intensity when progressively more distant from said surface; replenishing nutrient salts in the medium as they are consumed by said microalgae so that sufficient nutrients are maintained in said medium to sustain desired algal growth and reproduction rates; and injecting CO 2 into said medium in sufficient quantity to maintain a desired alkalinity and nutrient carbon content in said medium.

Claim 21

A continuous process for mass culture of a selected species of marine microalgae comprising: filling an algal culture container with a liquid culture medium precursor comprising sea water in which is dissolved a mixture of nutrient salts which, in grams per 100 liters of sea water, consists essentially of 50.7 g. HNO 3 , 7.8 g. H 3 PO 4 , 4.3 g. KCl. 1.86 g. Na 2 EDTA, 0.020 g. FeCl 3 .6H 2 O, 0.00368 g. (NH 4 ) 6 Mo 7 O 24 .4H 2 O, 0.00105 g. H 3 BO 3 , 0.00040 g. ZnCl 2 , and lesser amounts of both CuCl 2 .2H 2 O and MnCl 2 .4H 2 O; adding an amount of KOH to said precursor sufficient to adjust its pH to a level which facilitates a desired reproduction and growth pattern for a selected marine algal species and to complete said precursor's nutrient content whereby a liquid medium suitable for the growth of said marine algal species is formed; innoculating said medium with a culture of said algal species; circulating said innoculated medium through an open trough at an average depth of between 0.5 and 5.0 cm. by withdrawing medium from one end of the trough and replacing it in the other end; maintaining the temperature of said innoculated medium within a range conducive to the growth and reproduction of said algal species; channeling the flow of innoculated medium from said one end of said trough through the vertical stand pipe of a gas lift pump mechanism equipped for the injection of minute gas bubbles into liquid medium passing therethrough to: a. accomplish said circulating; and b. bring organic substances and the cells of said algal culture into contact with a stream of minute gas bubbles which are adsorbed thereon to increase the buoyancy of said organic substances and said microalgae so that they tend to rise to the surface of medium in the trough; moving liquid medium containing dissolved organic substances and algal cells with adsorbed minute gas bubbles through said trough at a rate such that the relatively small and light organic substances with adsorbed gas bubbles rise to the surface of said medium and the relatively large and heavier algal cells with adsorbed gas bubbles are carried by the current and not allowed to rise to said surface; skimming said organic substances from said surface; subsequently slowing the rate at which said liquid medium moves through said trough so that algal cells with adsorbed gas bubbles rise to said surface; skimming algal cells from said surface; exposing the surface of medium in the trough to sunlight which has been filtered by passage through a thin layer of an aqueous solution consisting essentially of water in which is dissolved an amount of CuSO 4 .5H 2 O sufficient to facilitate the photosynthesis of the microalgae by removing at least ninety-nine percent of all radiation below 350 nanometers and above 700 nanometers from the incident sunlight; alternately positioning individual cells of the algae in portions of said medium distant and adjacent to said medium surface and thus alternately exposing the cells to maximum light intensity when adjacent to said surface and decreasing light intensity when progressively more distant from said surface; replenishing nutrient salts in the medium as they are consumed by said microalgae so that sufficient nutrients are maintained in said medium to sustain desired algal growth and reproduction rates; and injecting into said medium at least 235 g. of CO 2 per 100 liters of medium per day.

Claim 22

A continuous process for mass culture of a selected species of marine microalgae comprising: filling an algal culture container with a liquid culture medium precursor comprising sea water in which is dissolved a mixture of nutrient salts which, in grams per 100 liters of sea water, consists essentially of 50.7 g. HNO 3 , 7.8 g. H 3 PO 4 , 4.3 g. KCl. 1.86 g. Na 2 EDTA, 0.020 g. FeCl 3 .6H 2 O, 0.00368 g. (NH 4 ) 6 Mo 7 O 24 .4H 2 O, 0.00105 g. H 3 BO 3 , 0.00040 g. ZnCl 2 , and lesser amounts of both CuCl 2 .2H 2 O and MnCl 2 .4H 2 O; adding an amount of KOH to said precursor sufficient to adjust its pH to a level which facilitates a desired reproduction and growth pattern for a selected marine algal species and to complete said precursor's nutrient content whereby a liquid medium suitable for the growth of said marine algal species is formed; innoculating said medium with a culture of said algal species; circulating said innoculated medium through an open trough at an average depth of between 0.5 and 5.0 cm. by withdrawing medium from one end of the trough and replacing it in the other end; maintaining the temperature of said innoculated medium within a range conducive to the growth and reproduction of said algal species; channeling the flow of innoculated medium from said one end of said trough through the vertical stand pipe of a gas lift pump mechanism equipped for the injection of minute gas bubbles into liquid medium passing therethrough to: a. accomplish said circulating; and b. bring organic substances and the cells of said algal culture into contact with a stream of minute gas bubbles which are adsorbed thereon to increase the buoyancy of said organic substances and said microalgae so that they tend to rise to the surface of medium in the trough; moving liquid medium containing dissolved organic substances and algal cells with adsorbed minute gas bubbles through said trough at a rate such that the relatively small and light organic substances with adsorbed gas bubbles rise to the surface of said medium and the relatively large and heavier algal cells with adsorbed gas bubbles are carried by the current and not allowed to rise to said surface; skimming said organic substances from said surface; subsequently slowing the rate at which said liquid medium moves through said trough so that algal cells with adsorbed gas bubbles rise to said surface; skimming algal cells from said surface; exposing the surface of medium in the trough to sunlight which has been filtered by passage through a thin layer of an aqueous solution consisting essentially of water in which is dissolved an amount of CuSO 4 .5H 2 O sufficient to facilitate the photosynthesis of the microalgae by removing at least ninety-nine percent of all radiation below 350 nanometers and above 700 nanometers from the incident sunlight; alternately positioning individual cells of the algae in portions of said medium distant and adjacent to said medium surface and thus alternately exposing the cells to maximum light intensity when adjacent to said surface and decreasing light intensity when progressively more distant from said surface; replenishing nutrient salts in the medium as they are consumed by said microalgae so that sufficient nutrients are maintained in said medium to sustain desired algal growth and reproduction rates; and injecting into said medium at least 235 g. of CO 2 per 100 liters of medium per day.