AU8150787A - A method for improving recovery by centrifugation of microorganisms from suspension in aqueous solutions - Google Patents
A method for improving recovery by centrifugation of microorganisms from suspension in aqueous solutionsInfo
- Publication number
- AU8150787A AU8150787A AU81507/87A AU8150787A AU8150787A AU 8150787 A AU8150787 A AU 8150787A AU 81507/87 A AU81507/87 A AU 81507/87A AU 8150787 A AU8150787 A AU 8150787A AU 8150787 A AU8150787 A AU 8150787A
- Authority
- AU
- Australia
- Prior art keywords
- centrifugation
- feed
- shear
- centrifuge
- algae
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims description 19
- 238000005119 centrifugation Methods 0.000 title claims description 12
- 238000011084 recovery Methods 0.000 title description 5
- 239000000725 suspension Substances 0.000 title description 5
- 239000007864 aqueous solution Substances 0.000 title description 4
- 244000005700 microbiome Species 0.000 title 1
- 239000000463 material Substances 0.000 claims description 21
- 241000195493 Cryptophyta Species 0.000 claims description 14
- 241000195634 Dunaliella Species 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 9
- 238000007865 diluting Methods 0.000 claims description 2
- 230000000063 preceeding effect Effects 0.000 claims 2
- 210000004027 cell Anatomy 0.000 description 16
- 238000010790 dilution Methods 0.000 description 15
- 239000012895 dilution Substances 0.000 description 15
- 238000003306 harvesting Methods 0.000 description 11
- OENHQHLEOONYIE-UKMVMLAPSA-N all-trans beta-carotene Natural products CC=1CCCC(C)(C)C=1/C=C/C(/C)=C/C=C/C(/C)=C/C=C/C=C(C)C=CC=C(C)C=CC1=C(C)CCCC1(C)C OENHQHLEOONYIE-UKMVMLAPSA-N 0.000 description 6
- TUPZEYHYWIEDIH-WAIFQNFQSA-N beta-carotene Natural products CC(=C/C=C/C=C(C)/C=C/C=C(C)/C=C/C1=C(C)CCCC1(C)C)C=CC=C(/C)C=CC2=CCCCC2(C)C TUPZEYHYWIEDIH-WAIFQNFQSA-N 0.000 description 6
- 235000013734 beta-carotene Nutrition 0.000 description 6
- 239000011648 beta-carotene Substances 0.000 description 6
- 229960002747 betacarotene Drugs 0.000 description 6
- 239000012267 brine Substances 0.000 description 6
- 238000001914 filtration Methods 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 6
- OENHQHLEOONYIE-JLTXGRSLSA-N β-Carotene Chemical compound CC=1CCCC(C)(C)C=1\C=C\C(\C)=C\C=C\C(\C)=C\C=C\C=C(/C)\C=C\C=C(/C)\C=C\C1=C(C)CCCC1(C)C OENHQHLEOONYIE-JLTXGRSLSA-N 0.000 description 6
- 238000004062 sedimentation Methods 0.000 description 5
- 241000195633 Dunaliella salina Species 0.000 description 4
- 230000006378 damage Effects 0.000 description 4
- 230000004075 alteration Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000013505 freshwater Substances 0.000 description 3
- 239000001963 growth medium Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002609 medium Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 235000021466 carotenoid Nutrition 0.000 description 1
- 150000001747 carotenoids Chemical class 0.000 description 1
- 230000005779 cell damage Effects 0.000 description 1
- 208000037887 cell injury Diseases 0.000 description 1
- 210000000170 cell membrane Anatomy 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- -1 for example Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002054 inoculum Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000008267 milk Substances 0.000 description 1
- 210000004080 milk Anatomy 0.000 description 1
- 235000013336 milk Nutrition 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000010977 unit operation Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B15/00—Other accessories for centrifuges
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B11/00—Feeding, charging, or discharging bowls
Landscapes
- Micro-Organisms Or Cultivation Processes Thereof (AREA)
- Preparation Of Compounds By Using Micro-Organisms (AREA)
Description
A METHOD FOR IMPROVING RECOVERY BY CENTRIFUGATION OF FRAGILE MATERIALS FROM SUSPENSION IN AQUEOUS SOLUTIONS
The present invention relates to a method of obtaining naturally occurring fragile material to be used, for example, in the harvesting of marine or salt tolerant species. In particular, the present invention relates to harvesting unicellular algae, such as, for example, of the genus Dunaliella, from fluids, such as, for example, brine, in order to recover materials of som economic value, such as, for example, carotenoids, particularly beta-carotene from the harvested material. Although the present invention will be described with particular reference to the harvesting of algae of the genus Dunaliella, it is to be noted that the present invention is not so limited and extends to include other methods of obtaining the naturally occurring raw material, and to raw materials other than the specific genus described herein.
Previous attempts to recover algae from brine have not entirely been successful for one or other reasons. One previous attempt is the subject of Australian Patent No. 486,999, which discloses a filtration process for the recovery of caroteniferous algae from brine suspensions in which a filter aid is added to a suspension of the algae prior to the recovery of the combined filter aid and algae by filtration. However, one disadvantage of this process includes the tendency of the microscopic algae to block the filter, even in the presence of the filter aid, which reduces the flow rate through the filter material. A further disadvantage is that large volumes of filter aid must be mixed with the algae in order to obtain reasonable filtration from which the desired algae is not readily separable after filtration which adds a further step to the overall process of obtaining the algae in a usable form.
Centrifugation is another cell harvesting technique which has been attempted, but has been found unsatisfactory because the action of most centrifuges
will rupture the algal cell membrane, and because separation efficiency of the algal cells from the brine is poor.
In one broad form the invention comprises an apparatus for the centrifugation of fragile material from a liquid medium, so constructed as to cause minimum shear during the centrifugation.
In another form the invention comprises a method of separating fragile material from a liquid medium by means of diluting the material to be collected in filtering the material through a centrifuge with minimum shear.
In one embodiment of the present invention there is provided an improved method for harvesting algae of the genus Dunaliella, which eleviates the problems of previously attempted methods related to this material. According to the preferred embodiment of the present invention, there is provided a number of "alterations to conventional centrifugation practices. The combined effect of these alterations makes centrifugation cost effective for separating species of the genus Dunaliella and other materials.
The majority of industrial centrifuges cause unacceptably high levels of cell rupture to Dunaliella species, or any other fragile materials. Members of the genus Dunaliella do not have a cell wall, but are surrounded by a thin elastic membrane or periplast, this makes the cells particularly susceptible to rupture.
Shear and cavitation within the centrifuge are two major reasons for damage to fragile materials. The amount of damage can be minimised by alterations to the machine, and by choosing a machine with specific features to minimise shear. One or several or all of the following features help reduce damage to fragile materials: 1. Hermetic centrifuge design which restricts the entry of air thereby limiting cavitation. 2. Feed and discharge pumps, whether they be an integral part of the centrifuge or separate to the centrifuge, should be of a design which minimises
shear. 3. The liquid entering the machine should be gradually accelerated in angular velocity, to minimise shear as the liquid enters the bowl. Gradual acceleration in angular velocity can be achieved by introducing liquid into the bowl through a rotating hollow spindle as, for instance, found in certain hermetic milk separators.
Certain centrifuges can be altered to reduce cell rupture by removing feed and/or discharge paring discs.
The paring discs are centripetal pumps in the centrifuge, they create shear which damages fragile materials. When the feed paring disc is removed, it would be necessary to feed the machine using an external pump of a type which would cause minimal shear.
The separation efficiency of Dunaliella and other materials from brine or other media using a centrifuge can, in some circumstances, be improved dramatically by dilution of the media. Dilution of the media causes a number of changes to the physical characteristics of the algae and the continuous phase (media) which affect sedimentation velocity:
1. Dilution of the culture media causes lowering of the density of the media. The lowering of the density of the media should lead to an increase in the difference in density between the algal cells and the media, thereby increasing sedimentation velocity. 2. Viscosity of the media will be reduced by dilution, this will increase sedimentation velocity of algal cells. 3. Dilution of algal culture media is reported to cause swelling of the algal cells. The swelling of the algal cells effectively increases particle diameter, therefore increasing sedimentation velocity.
The increased sedimentation velocity caused by the dilution will lead to an improvement in separation
efficiency.
An application of the invention for commercial harvesting of Dunaliella species is represented in Figure
1. This manner of harvesting Dunaliella has a number of advantages over other harvesting methods, including filtration and flocculation methods. These advantages include:
1. Minimisation of the number of unit steps in harvesting. 2. The Dunaliella cells not recovered during the harvesting operation are not damaged, hence, they can be immediately returned to the growing ponds as seed inoculum.
3. Dilution of the culture, as recommended in this invention, is an advantage in most Dunaliella production situations. Dunaliella species are naturally occurring, and usually cultivated, in an environment where evaporation rate is extremely high. Hence, dilution of the growing media is necessary to maintain constant salinity. Dilution and mixing of the Dunaliella salina culture during the harvesting operation reduces the number of unit operations in algal production, and improves mixing of dilution water and brine before return into growing ponds.
EXAMPLE 1
Operating "Alfa Laval" Model 2181 centrifuge with and without feed paring disc.
4 A Dunaliella salina culture, containing 6.9 x 10 cells. Ml was pumped into an "Alfa Laval" Model 2181 centrifuge. The pump was a "Mono" helical rotor pump which was coupled to a "Toshiba" Inverter to allow accurate variable flow rate.
The centrifuge was first tested with the paring discs on the feed discharge removed. In the culture discharged from the centrifuge it was found that there was negligible cell damage.
The centrifuge was then tested with the feed paring disc inserted and the discharge paring disc removed. A
feed nozzle designed for maximum throughput was inserted into the feed paring disc. Culture from the discharge was examined microscopically. Ruptured cells and active cells were counted, and it was noted that significant cell rupture was caused when the centrifuge was operated with the feed paring disc inserted. The results are shown in Figure 2.
EXAMPLE 2
Separation efficiencies at different dilution. A Dunaliella salina culture, containing 7.2 x 10 cells, ml- , was pumped into an "Alfa Laval" Model
2181 centrifuge with both feed and discharge paring discs removed. Before entering the centrifuge the algal culture was mixed with freshwater in a "Lightnin" static mixer. Flowrates of fresh water and culture were controlled by identical variable speed "Mono" helical rotor pumps. A diagram indicating the equipment used in this test is given in Figure 3.
The amount of beta-carotene in the discharge from the centrifuge was determined (the beta-carotene concentration being proportional to the concentration of Dunaliella salina cells) . From these results the amount of beta-carotene recovered in the centrifuge was calculated. The results of this test are given in Figure 4. It can be seen that dilution of the culture increases separation efficiency markedly at flowrates over 500 litres. hr~ (for example, at a culture flowrate of 3,000 litres. hr~ with no dilution 3.6 grams of beta-carotene. hr~ was recovered. At a culture flowrate of 3,000 litres. hr~ with dilution of 1 part culture to 1 part freshwater 11.7 grams of beta-carotene, hr- was recovered) .
It should therefore be obvious that the present invention provides an improved method of recovery by centrifugation of fragile materials from suspension in aqueous solutions of about 30 parts per thousand or greater, which comprises the steps of:
(a) Dilution of the culture prior to feeding into the 'centrifuge to improve separation efficiency; and
(b) Utilising a centrifuge in which the shear is minimised.
This can be caused by the removing from conventional centrifuges of the feed paring discs, the feed nozzle and the discharge paring disc. Further, the feed to the centrifuge could be by way of a low shear pump as a distinct entity to that of the centrifuge, whereby the aqueous solution is gradually accelerated in angular velocity to approximately match up to that of the centrifuge itself.
Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall into its spirit and scope.
Claims (13)
1. An apparatus for the centrifugation of fragile material from a liquid medium so constructed as to cause minimum shear during the centrifugation.
2. An apparatus according to claim 1 comprising hermetic seals to restrict the entry of air therein to limit cavitation.
3. An apparatus according to claim 1 or 2, wherein the feed and discharge pumps are designed to minimise shear.
4. An apparatus according to any one of the preceeding claims wherein means are provided to gradually accelerate, in angular velocity, the liquid entering the apparatus.
5. An apparatus according to claim 4, wherein said means comprises a rotating hollow spindle.
6. An apparatus according to any one of the preceeding claims wherein the apparatus comprises external feed and discharge pumps of a type which causes minimal shear, and the apparatus has its paring discs removed.
7. A method for the centrifugation of fragile material from a liquid medium whereby the fragile material is separated from the medium with minimum shear during the centrifugation.
8. A method according to claim 7 including the step of gradually accelerating in angular velocity the liquid entering the apparatus.
9. An apparatus according to claim 7 or 8 using feed and discharge pumps which are designed to minimise shear.
10. A method according to any one of claims 7 to 9 including the step of restricting the entry of air to the apparatus to limit cavitation.
11. A method according to any one of claims 7 to 10 including the step of diluting of the media.
12. A method according to any one of claims 7 to 11 wherein the fragile material is unicellular algae.
13. A method according to claim 12 wherein the algae is of the genus Dunaliella.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPH8566 | 1986-10-17 | ||
| AUPH856686 | 1986-10-17 | ||
| AUPI0402 | 1987-02-17 | ||
| AUPI040287 | 1987-02-17 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU8150787A true AU8150787A (en) | 1988-05-06 |
| AU611869B2 AU611869B2 (en) | 1991-06-27 |
Family
ID=25643189
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU81507/87A Ceased AU611869B2 (en) | 1986-10-17 | 1987-10-16 | A method for improving recovery by centrifugation of microorganisms from suspension in aqueous solutions |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU611869B2 (en) |
| IL (1) | IL84197A (en) |
| WO (1) | WO1988002662A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104277976A (en) * | 2014-10-22 | 2015-01-14 | 临沂大学 | Purification and domestication method for dunaliella tertiolecta |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU486999B2 (en) * | 1973-08-16 | 1976-02-19 | Bayonet Pty. Ltd. | Recovery of algae from brine suspensions |
| SE393542B (en) * | 1975-09-17 | 1977-05-16 | Alfa Laval Ab | DEVICE AT CENTRIFUGAL SEPARATOR WITH OPERATING OPENABLE OUTLET AT THE PERIOD OF THE ROTOR AND WITH THE STATIONING SCALE BODY FOR DISPOSAL OF SEPARATED LIQUID |
| IL49726A (en) * | 1976-06-06 | 1979-09-30 | Yeda Res & Dev | Production of glycerol from algae |
| US4199895A (en) * | 1977-05-25 | 1980-04-29 | Yeda Research And Development Co. Ltd. | Production of glycerol, carotenes and algae meal |
| BR8207915A (en) * | 1981-10-07 | 1983-09-13 | Commw Scient Ind Res Org | SEAWEED HARVEST METHOD |
| AU6533186A (en) * | 1985-11-01 | 1987-05-14 | Commonwealth Of Australia, The | Cultivation of dunaliella salina for b-carotene production |
-
1987
- 1987-10-16 AU AU81507/87A patent/AU611869B2/en not_active Ceased
- 1987-10-16 WO PCT/AU1987/000354 patent/WO1988002662A1/en not_active Ceased
- 1987-10-18 IL IL84197A patent/IL84197A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| AU611869B2 (en) | 1991-06-27 |
| IL84197A0 (en) | 1988-03-31 |
| WO1988002662A1 (en) | 1988-04-21 |
| IL84197A (en) | 1992-01-15 |
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