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US-12617702-B2 - Method for producing biomass from a microalgae

US12617702B2US 12617702 B2US12617702 B2US 12617702B2US-12617702-B2

Abstract

A method for producing biomass from a microalgae includes culturing the microalgae in an effluent diluted in seawater. A method for bioremediating an effluent includes culturing a microalgae in the effluent diluted in seawater. The microalgae is at least one of a strain of the genus Nodularia, a strain of the genus Chrysoreinhardia, a strain of the genus Halochlorella, or combinations thereof. At the beginning of culturing, the diluted effluent exhibits concentrations of total nitrogen (N) in the range of 30-150 mg/l and concentrations of total phosphorus (P) in the range of 1-15 mg/l. The N/P quotient is in the range of 5-40.

Inventors

  • Agustín Portillo Hahnefeld
  • Antera Martel Quintana
  • Juan Luis Gómez Pinchetti

Assignees

  • UNIVERSIDAD DE LAS PALMAS DE GRAN CANARIA

Dates

Publication Date
20260505
Application Date
20210115
Priority Date
20200117

Claims (20)

  1. 1 . A method for producing biomass from a microalgae, comprising: culturing the microalgae in an effluent diluted in seawater, wherein the microalgae is at least one of a strain of the genus Nodularia , a strain of the genus Chrysoreinhardia , a strain of the genus Halochlorella , or combinations thereof, wherein, at the beginning of culturing, the diluted effluent exhibits: concentrations of total nitrogen (N) in the range of 30-150 mg/l; and concentrations of total phosphorus (P) in the range of 1-15 mg/l, wherein the N/P quotient is in the range of 25-40.
  2. 2 . The method according to claim 1 , wherein the strain of the genus Nodularia is at least one of a strain of the species Nodularia spumigena or a strain of the species Nodularia harveyana, wherein the strain of the genus Chrysoreinhardia is a strain of the species Chrysoreinhardia giraudii , and wherein the strain of the genus Halochlorella is a strain of the species Halochlorella rubescens.
  3. 3 . The method according to claim 2 , wherein the strain of the species Nodularia spumigena is BEA_IDA_0069B, wherein the strain of the species Nodularia harveyana is BEA_IDA_0070B, wherein the strain of the species Chrysoreinhardia giraudii is BEA_IDA_0071B, and wherein the strain of the species Halochlorella rubescens is BEA_IDA_0072B.
  4. 4 . The method according to claim 1 , wherein the concentration of ammonium (N-NH 4 + ) with respect to the concentration of total nitrogen (N) in the diluted effluent is at least 50%.
  5. 5 . The method according to claim 1 , wherein inoculation of the microalgae in the effluent diluted in seawater is carried out with at least 50 mg/l of dry biomass.
  6. 6 . The method according to claim 1 , further comprising: harvesting the biomass from the microalgae by filtration.
  7. 7 . The method according to claim 1 , wherein the culturing is carried out in photobioreactors under outdoor environmental conditions.
  8. 8 . The method according to claim 1 , wherein the culturing is carried out under a mean irradiation of at least 1750 μmoles photons/m 2 ·s.
  9. 9 . A method for bioremediating an effluent, comprising: culturing a microalgae in the effluent diluted in seawater, wherein the microalgae is at least one of a strain of the genus Nodularia , a strain of the genus Chrysoreinhardia , a strain of the genus Halochlorella , or combinations thereof, wherein, at the beginning of culturing, the diluted effluent exhibits: concentrations of total nitrogen (N) in the range of 30-150 mg/l; and concentrations of total phosphorus (P) in the range of 1-15 mg/l, wherein the N/P quotient is in the range of 5-4025-40.
  10. 10 . The method, according to claim 9 , wherein the strain of the genus Nodularia is at least one of a strain of the species Nodularia spumigena or a strain of the species Nodularia harveyana , wherein the strain of the genus Chrysoreinhardia is a strain of the species Chrysoreinhardia giraudii , and wherein the strain of the genus Halochlorella is a strain of the species Halochlorella rubescens.
  11. 11 . The method according to claim 10 , wherein the strain of the species Nodularia spumigena is BEA_IDA_0069B, wherein the strain of the species Nodularia harveyana is BEA_IDA_0070B, wherein the strain of the species Chrysoreinhardia giraudii is BEA_IDA_0071B, and wherein the strain of the species Halochlorella rubescens is BEA_IDA_0072B.
  12. 12 . The method according to claim 9 , wherein the concentration of ammonium (N-NH 4 + ) with respect to the concentration of total nitrogen (N) in the diluted effluent is at least 50%.
  13. 13 . The method according to claim 9 , wherein inoculation of the microalgae in effluent diluted in seawater is carried out with at least 50 mg/l of dry biomass.
  14. 14 . The method according to claim 9 , further comprising: harvesting the biomass from the microalgae by filtration.
  15. 15 . The method according to claim 9 , wherein the culturing is carried out in photobioreactors under outdoor environmental conditions.
  16. 16 . The method according to claim 9 , wherein the culturing is carried out under a mean irradiation of at least 1750 μmoles photons/m 2 ·s.
  17. 17 . A method for producing a processed material from microalgal biomass, comprising: (a) producing microalgal biomass according to the method of claim 1 , and (b) producing a processed material from the microalgal biomass.
  18. 18 . The method according to claim 17 , wherein the processed material is selected from the group consisting of a fertiliser, pesticide, feed, feed for fish, biofuel, jet fuel, biodiesel, pigment, surfactant, cosmetic, pharmaceutical agent, nutraceutical product, prebiotic product, probiotic product, functional food, health supplement, and bioplastics.
  19. 19 . A method for producing a biomass extract from a microalgae, comprising: i) culturing the microalgae in an effluent diluted in seawater, wherein the microalgae is at least one of a strain of the genus Nodularia , a strain of the genus Chrysoreinhardia , a strain of the genus Halochlorella , or combinations thereof, wherein, at the beginning of culturing, the diluted effluent exhibits: concentrations of total nitrogen (N) in the range of 30-150 mg/l; and concentrations of total phosphorus (P) in the range of 1-15 mg/l, wherein the N/P quotient is in the range of 25-40; ii) harvesting the biomass from the microalgae by filtration; iii) subjecting the microalgal biomass to a cellular breakage method; and iv) obtaining the extract resulting from cellular breakage.
  20. 20 . The method of claim 19 , wherein the cellular breakage method is carried out with a system selected from the group consisting of a ball mill, a system delivering microwaves, and a system delivering a pulsed electric field.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the United States national phase of International Application No. PCT/ES2021/070017 filed Jan. 15, 2021, and claims priority to Spanish Patent Application No. P202030030 filed Jan. 17, 2020, the disclosures of which are hereby incorporated by reference in their entirety. BACKGROUND Field The invention relates to the use of effluents from wastewater treatment as a source of nutrients for culturing microalgae. Description of Background Art Water contamination is one of the most serious problems for our planet, which, together with the limitations in the availability of water in large areas of the planet, can result in a danger to the health of the population. Currently, all wastewater in developed countries is treated in main treatment plants and, subsequently, the discharge thereof into the sea or rivers is allowed, after a series of complex purification treatments. In a wastewater purification process, the sludge accumulated in an initial filtration phase is treated in anaerobic digesters, to reduce the volume and toxicity thereof. This process mainly produces methane, dry sludge and reject water (effluent). Methane is reused as a source of energy in many treatment plants, dry sludge is generally reused as peat, but the fraction of reject water (effluent) returns to the treatment plant to be treated. This type of water is a big problem, since this effluent exhibits a very significant contaminant load, with high concentrations of nitrate, ammonium and phosphate, BOD and COD, as well as bacteria. The incorporation of this type of water in the flow of a wastewater treatment plant causes a severe problem since the effluent alters all the chemical parameters of the treated water. For this reason, in some treatment plants it is stored until favourable conditions are found for the purification thereof. The composition of the effluent varies considerably from one region to another and is always a function of the origin of the sludge being treated. Its high contaminant load, high concentrations of ammonia and bacteria, as well as numerous infectious agents harmful to the population, animals and plants are also evident. Currently, the removal of contaminants from this water is very costly and time consuming. However, this reject water (effluent) can be used as a source of nutrients for culturing microalgae, since it contains nutritional requirements of algae in an adequate proportion, in addition to a much lower bacterial concentration since the effluent is typically obtained under anaerobic conditions. In addition to being useful in the purification of this wastewater, the use of an effluent as a source of nutrients for culturing microalgae leads to the production of biomass with economic benefit. This biomass can be used as a source for a fertiliser, pesticide, feed, feed for fish, biofuel, jet fuel, biodiesel, pigment, surfactant, cosmetic, pharmaceutical agent, health supplement, or the manufacture of bioplastic. The use of wastewater treatment effluent as a source of nutrients for the production of microalgal biomass has been shown to be effective in many recent studies. The eukaryotic microalgae most frequently used in wastewater treatment are of the genus Chlorella, Scenedesmus, Muriellopsis, Botryococcus and Nannochloropsis and also the cyanobacterium Phormidium bohneri. However, the optimal effluent concentration that can be used as a source of nutrients in the production of microalgae has to be individually studied in each case. It must be taken into account that the effluent concentration varies widely from one treatment plant to another. Therefore, the growth rate and robustness of microalgal cultures are not in all cases sufficient to be efficient in water purification. Therefore, detecting, bioprospecting, identifying and characterising strains continues to be one of the fundamental objectives in this type of study, to search for the highest production rates, the ability to remove nutrients, resistance to pathogens and bacteria, and the optimisation of the biomass obtained. SUMMARY The inventors have found that the strains of eukaryotic microalgae Chrysoreinhardia giraudii BEA_IDA_0071B and Halochlorella rubescens BEA_IDA_0072B, and strains of cyanobacteria Nodularia spumigena BEA_IDA_0069B (according to a previous taxonomic study, the strain BEA_IDA_0069B had been identified with a species of Anabaena sp.) and Nodularia harveyana BEA_IDA_0070B (according to a previous taxonomic study, the strain BEA_IDA_0070B had been identified with a species of Dolichospermum sp.) exhibit significant rates of biomass production and removal of contaminants when cultured in a culture medium prepared by diluting an effluent from the Salto del Negro treatment plant (Gran Canaria, Spain) in seawater at 0.5%, in such a way that, in the diluted effluent, concentrations of N—total nitrogen (ammonium and nitrate)—of 106 mg/l and concentrations of P—total phosphorus (