Harvest and concentration process for microalgae species

1 . A method of obtaining microalgae from a liquid source material, wherein the microalgae have a concentration in a final concentrated solid-containing fraction of at least 10 wt %, based on the total weight of the final concentrated solid-containing fraction, wherein the method comprises:

introducing a liquid source material to an apparatus to yield the final concentrated solid-containing fraction, said apparatus comprising:

at least one leg for separating and concentrating a liquid source material to yield the final concentrated solid-containing fraction, wherein each leg comprises:

(i) a separation unit comprising at least one separation stage, wherein each separation stage comprises an apparatus that can dewater the liquid source material to yield a first liquid fraction and a separation stage solid-containing fraction, wherein when there is more than one separation stage, they are communicatively connected (I) in series, and a separation stage solid-containing fraction is serially moved through to a next separation stage in the series for additional dewatering, or (II) in parallel, wherein separation stage solid-containing fractions from each separation stage are combined, or (III) combination of both (I) and (II), eventually yielding a final separation solid-containing fraction; and

(ii) a concentration unit comprising at least one concentration stage, wherein each concentration stage comprises an apparatus that can concentrate the final separation solid-containing fraction to yield a second liquid fraction and a concentrated solid-containing fraction, wherein when there is more than one concentration stage, they are communicatively connected (I) in series, and a concentration stage solid-containing fraction is serially moved through to a next concentration stage in the series for additional concentration, or (II) in parallel, wherein concentration stage solid-containing fractions from each concentration stage are combined, or (III) combination of both (I) and (II), eventually yielding the final concentrated solid-containing fraction.

2 . The method of claim 1 , further comprising drying the final concentrated solid-containing fraction.

3 . The method of claim 1 , wherein prior to introduction to the apparatus, the liquid source material is introduced to at least one pre-filtration unit to remove unwanted materials from the liquid source material, wherein the at least one pre-filtration unit comprises a device selected from the group consisting of centrifuges, vibrating screens, mesh screening, belt filters, screw presses, hydrocyclones, HELLAN strainers, paddle strainers, and sieve bend screens.

4 . The method of claim 1 , wherein prior to introduction to the apparatus, the liquid source material is introduced to at least one invasive pest filtration unit to remove invasive pests from the liquid source material.

5 . The method of claim 1 , wherein the separation unit comprises from one to 50 separation stages.

6 . The method of claim 1 , wherein at least one separation stage comprises an inside-out hollow fiber filtration apparatus, wherein a feed is introduced inside of a hollow fiber lumen and a liquid fraction permeates from inside the hollow fiber lumen to outside of the hollow fiber lumen.

7 . The method of claim 1 , wherein a plot of flux rate in each separation unit as a function of dry matter content resembles an asymptotic curve.

8 . The method of claim 1 , wherein the concentration unit comprises from one to 50 concentration stages, wherein each concentration stage comprises a concentration device that is the same as, or different from, concentration devices in the other concentration stages.

9 . The method of claim 8 , wherein the concentration device is selected from the group consisting of a cross-flow filtration cassette, a centrifuge, an evaporator, and a filter press.

10 . The method of claim 9 , wherein the cross-flow filtration cassette comprises at least one assembly, wherein the at least one assembly comprises:

a multilaminate array of sheet members of generally rectangular and generally planar shape, each sheet of the array having a first end, a second end longitudinally opposite the first end, and a thickness, wherein the sheet members comprise in sequence in said array, a first retentate sheet, (a permeate pack and a second retentate sheet) n, wherein n=1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more, wherein the permeate pack comprises a first filter sheet, a permeate sheet, and a second filter sheet, wherein each sheet in each permeate pack has at least one fluid opening at the first end thereof and at least one fluid opening at the second end thereof, wherein corresponding fluid openings at the first end of each sheet in each permeate pack are in register with one another and corresponding fluid openings at the second end of each sheet in each permeate pack are in register with one another, wherein the first and second retentate sheets have at least one channel opening therein, each channel opening extending longitudinally between a first channel entrance positioned proximate to fluid openings at the first end of the permeate pack and a second channel entrance positioned proximate to fluid openings at the second end of the permeate pack in the array, and wherein the at least one channel opening is open through the entire thickness of the first and second retentate sheets to permit a fluid to contact adjacent filter sheets, and wherein the first and second retentate sheets are bonded to adjacent filter sheets about peripheral end and side portions thereof; and

two assembly end plates sandwiching the multilaminate array of sheets, each end plate having a first end and a second end corresponding to that of the multilaminate array of sheets, wherein the two assembly end plates comprise at least one fluid opening at the first end thereof and at least one fluid opening at the second end thereof, wherein fluid openings of the end plates are in register with corresponding fluid openings of the permeate pack,

wherein the at least one assembly further comprises at least one permeate passage opening at longitudinal side margin portions of the assembly.

11 . The method of claim 10 , wherein the cross-flow filtration cassette further comprises at least one of options (I), (II), (III), or (IV), or any combination of (I)-(IV):

(I) a cap positioned on at least a portion of at least one fluid opening of the permeate pack, wherein the cap is positioned proximate to channel entrances of the first and second retentate sheets;

(II) the fluid openings at the first end, the fluid openings at the second end, or both the fluid openings at the first and second end, are cut as an irregular pentagon having a “V” positioned proximate to the channel openings of the first and second retentate sheets;

(III) a first permeate screen spacer positioned between the first filter sheet and the permeate sheet, a second permeate screen spacer positioned between the second filter sheet and the permeate sheet, or both, wherein each permeate screen spacer has a first end and a second end corresponding to that of the multilaminate array of sheets, wherein the permeate screen spacers comprise at least one fluid opening at the first end thereof and at least one fluid opening at the second end thereof, wherein fluid openings of the permeate screen spacers are in register with corresponding fluid openings of the permeate pack;

(IV) the permeate sheet comprises a metal matrix or other reinforced porous material of requisite thickness.

12 . The method of claim 1 , wherein prior to introduction to the at least one leg, the microalgae are cultivated in at least one incubator.

13 . The method of claim 12 , wherein the at least one incubator comprises a Photobio Reactor (PBR) and/or an Open Raceway Pond (ORP).

14 . The method of claim 1 , wherein a portion of the final separation solid-containing fraction is directed to a low inoculation concentration algae storage container.

15 . The method of claim 1 , wherein at least 50% of the microalgae cells in the final separation solid-containing fraction are viable.

16 . The method of claim 1 , further comprising recycling the first liquid fraction, the second liquid fraction, or both, back to at least one incubator for reuse as cultivation media.