Description:ASTAXANTHIN PRODUCING PHOTO BIOREACTOR (PBR) FOR MICROALGAE CULTIVATION
FIELD OF THE INVENTION
[0001] This invention generally relates to a field of bio-process engineering, more particularly to an astaxanthin producing photo bioreactor (PBR) for microalgae cultivation.
BACKGROUND
[0002] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.
[0003] Photo bioreactors (PBRs) are widely used for cultivating microalgae and other photosynthetic organisms, but conventional designs may face significant challenges that impact efficiency and sustainability. Existing PBRs are primarily made of glass or high-grade plastics that are expensive and suffer from transparency issues due to biofilm formation, necessitating frequent cleaning, which is both labour-intensive and time-consuming. Additionally, these PBR reactors require careful handling to prevent breakage, increasing maintenance costs. Biomass harvesting poses another challenge, as exposure to external contaminants during the process may compromise culture integrity. Furthermore, the production of glass for PBR construction may contribute to greenhouse gas emissions due to the high-energy melting process, further exacerbating environmental concerns.
[0004] Furthermore, the artificial media like BG-11 and Bold Basal Medium provide a controlled environment for astaxanthin production and their high cost may limit the large-scale applications. Further, the high organic content may also lead to microbial competition, reducing the efficiency of astaxanthin production. Moreover, proper management is needed to prevent issues like biofouling and reactor clogging, which could increase maintenance efforts.
[0005] According to a patent application “US20150252391A1” titled “Method using microalgae for high-efficiency production of astaxanthin” discloses a novel method for producing astaxanthin by using microalgae. The method comprises: heterotrophic cultivation of microalgae, dilution, photo-induction, collection of microalgal cells, and extraction of astaxanthin. The method according to the present invention takes full advantages of rapid growth rate in the heterotrophic stage and fast accumulation of astaxanthin in the photo-induction stage by using a large amount of microalgal cells obtained in the heterotrophic cultivation stage, so as to greatly improve the astaxanthin production rate and thereby achieve low cost, high efficiency, large scale production of astaxanthin by using microalgae. The method not only provides an important technical means to address the large-scale industrial production of astaxanthin through microalgae but also ensures an ample source of raw material for the widespread utilization of astaxanthin.
[0006] According to a patent application “KR20140078187A” discloses photo bioreactor for culturing micro algae” a structure of a photobioreactor for microalgae culturing in which the microalgae incubator is provided with a closed structure by using rollers and water pressure to increase the fixing efficiency of carbon dioxide (CO2) by microalgae and reduce the installation cost. More particularly, the present invention relates to a culture tank for storing cultured water containing microalgae, comprising a culture tank into which carbon dioxide (CO 2) is introduced, a water tank formed in at least one side of the culture tank and storing water (H2O) And a cover covering an upper portion of the culture tank, wherein a channel is formed in the culture tank and the lower part of the water tank.
[0007] However, the existing PBR reactors require careful handling to prevent breakage, increasing maintenance costs. Biomass harvesting poses another challenge, as exposure to external contaminants during the process may compromise culture integrity. Furthermore, the production of glass for PBR construction may contribute to greenhouse gas emissions due to the high-energy melting process, further exacerbating environmental concerns.

OBJECTIVES OF THE INVENTION
[0009] The objective of present invention is to provide an astaxanthin producing photo bioreactor (PBR) for microalgae cultivation
[0010] Further, the objective of present invention is to provide the photo bioreactor that utilizes acrylic sheets for enhanced light entrapment, durability, and cost-effectiveness compared to conventional glass-based bioreactors.
[0011] Furthermore, the objective of the present invention is to provide the photo bioreactor that utilizes dairy wastewater (DWW) blended with BG-11 media, thereby reducing dependence on expensive synthetic growth media.
[0012] Furthermore, the objective of the present invention is to provide the photo bioreactor that ensures that the acrylic-based PBR has a durability of more than 10 years, reducing maintenance costs.
[0013] Furthermore, the objective of the present invention is to provide the photo bioreactor to implement UV-Vis spectroscopy or equivalent analytical methods to assess biomass accumulation and pigment synthesis.
SUMMARY
[0014] According to an aspect, the present embodiments an astaxanthin producing photo bioreactor (PBR) for microalgae cultivation. Further, the bioreactor comprises a bioreactor body crafted with plurality of acrylic sheets, wherein the plurality of acrylic sheets is configured to provide higher strength, flexibility, and transparency. Further, at least one tap having a micro-filter, integrated within the bioreactor body, wherein the at least one tap enables a user daily biomass growth observation and harvesting of final product. Further, at least one motorized shaking mechanism attached within the body of bioreactor for agitating algae cultures to prevent settling of culture and biomass growth.
[0015] According to another aspect, a method for producing astaxanthin using the photo bioreactor comprising filtering dairy wastewater (DWW) using cellulose membrane filtration to remove undesirable particulates and impurities. Further, subjecting the pre-filtered DWW to vacuum filtration to the medium for enhanced microalgae growth. Further, using the filtered DWW as a culture medium for microalgae cultivation using the photo-bioreactor. Further, agitating the culture using the motorized shaking mechanism at regular intervals to prevent sedimentation and ensure uniform growth. Further, harvesting biomass through at least one tap. Further, monitoring microbial growth using UV-Vis spectroscopy to facilitate real-time observation of biomass accumulation and astaxanthin (i.e., pigment) synthesis.

BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the invention. Any person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g. boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It may be that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another, and vice versa. Furthermore, elements may not be drawn to scale. Non-limiting and non-exhaustive descriptions are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles.
[0002] FIG. 1 illustrates an isometric view of an astaxanthin producing photo bioreactor (PBR) for microalgae cultivation, according to an embodiment of the present invention;
[0003] FIG. 2 illustrates a method for producing astaxanthin using the photo bioreactor, according to an embodiment of the present invention;
[0004] FIG. 3 illustrates a tabular representation of a blends of BG11 and dairy waste water, according to an embodiment of the present invention;
[0005] FIG. 4 illustrates a graphical representation of growth of the microalgae, according to an embodiment of the present invention;
[0006] FIG. 5 illustrates a tabular representation of biochemical analysis of extracted pigment, according to an embodiment of the present invention; and
[0007] FIG. 6 illustrates a tabular representation of a mineral analysis of the extracted pigment, according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0017] Some embodiments of this invention, illustrating all its features, will now be discussed in detail. The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.
[0018] Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred, systems and methods are now described. Embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples among other possible examples.
[0019] The present invention discloses a novel and effective astaxanthin producing photo bioreactor (PBR) for microalgae cultivation.
[0020] FIG. 1 illustrates an isometric view of an astaxanthin producing photo bioreactor (PBR) for microalgae cultivation, according to an embodiment of the present invention.
[0008] In first embodiment, the bio-reactor (100) (100) comprises a bioreactor (100) body (102) crafted with plurality of acrylic sheets (104), at least one tap (106) having a micro-filter, integrated within the bioreactor body (102), and at least one motorized shaking mechanism (108) attached within the body (102) of bioreactor (100).
[0009] Further, the bioreactor (100) comprises plurality of acrylic sheets (104) to form the bioreactor body (102). The use of acrylic sheets (104) offers higher strength, flexibility, and transparency compared to traditional materials such as glass. The structural advantage ensures better light entrapment, which enhances photosynthetic efficiency for improved biomass production. Additionally, acrylic is durable (more than a 10 year) and lightweight, making the bioreactor (100) a cost-effective, long-term solution for industrial and research applications in algal biotechnology.
[0010] Furthermore, the bioreactor (100) comprises at least one tap (106) integrated with a micro-filter, allowing users to observe daily biomass growth and harvest the final product with minimal contamination risks. The at least one tap (106) feature may ensure that microalgae cultivation is both efficient and controlled, reducing manual handling and contamination risks. The presence of a micro-filter within the tap (106) may enable the selective extraction of culture medium or biomass, preventing unwanted microbial intrusion while ensuring sterile and efficient harvesting of microalgae for biofuel, pharmaceutical, or nutraceutical applications.
[0011] In some embodiments, in order to prevent culture settling and promote uniform growth, the bioreactor (100) is equipped with at least one motorized shaking mechanism (108). The at least one motorized shaking mechanism (108) may ensure continuous agitation of the algae culture that helps to maintain uniform nutrient distribution and prevents cell clumping. By providing a controlled mixing environment, the bioreactor (100) optimizes gas exchange and light exposure in order to enhance the overall biomass yield. The integration of CO2 and oxygen supply, coupled with real-time monitoring using pH and temperature sensors making the bio reactor (100) ideal for high-efficiency micro-algal cultivation under varied environmental conditions.
[0012] In some embodiments, the bioreactor (100) is integrated with at least one tap (106) with a micro-filter (0.2µm) to enable daily biomass growth observation and sterile harvesting, minimizing contamination risks. Additionally, a motorized shaking mechanism (108) is incorporated within the system to agitate algae cultures, preventing culture settling and ensuring uniform nutrient distribution. The bioreactor (100) further includes a CO2 inlet, gas mixer, and oxygen pump to maintain optimal gas exchange, alongside pH and temperature sensors for real-time monitoring. A detachable lid and media inlet port facilitate controlled nutrient addition and maintenance, making the bioreactor (100) ideal for biofuel production, wastewater treatment, and pigment extraction in an economically viable and sustainable manner.
[0013] FIG. 2 illustrates a method (200) for producing astaxanthin using the photo bioreactor (100), according to an embodiment of the present invention. FIG. 3 illustrates a tabular representation (300) of a blends of BG11 and dairy waste water, according to an embodiment of the present invention.
[0014] In some embodiments, dairy wastewater (DWW) is filtered using cellulose membrane filtration to remove undesirable particulates and impurities, at step 202. The process of filtering dairy wastewater (DWW) using cellulose membrane filtration involves passing the wastewater through a cellulose-based membrane in order to remove undesirable particulates, suspended solids, and impurities while retaining essential nutrients required for microalgae cultivation. Further, the microalgae strain used corresponds to Scenedesmus abundans. The filtration step enhances the clarity and sterility of the wastewater, preventing contamination and enabling better nutrient absorption by microalgae. The cellulose membrane may ensure the removal of large organic matter, bacteria, and debris, making the filtered DWW a suitable, cost-effective, and eco-friendly alternative to synthetic growth media in microalgae-based bioprocesses.
[0015] In some embodiments, the pre-filtered DWW is subjected to vacuum filtration to the medium for enhanced microalgae growth, at step 204. The pre-filtered dairy wastewater (DWW) undergoes vacuum filtration to further purify the medium in order to ensure optimal conditions for microalgae growth. The process involves using a vacuum pump to create a pressure differential that accelerates the removal of fine particulates, residual bacteria, and unwanted impurities, resulting in a sterile and nutrient-rich medium. Vacuum filtration enhances micro-algal uptake of essential elements, leading to higher biomass productivity and efficient cultivation in the photo bioreactor (100).
[0016] In an example embodiment, the filtered dairy wastewater (DWW) media is inoculated under laminar airflow (LAF) conditions to maintain sterility and minimize contamination risk during microalgae cultivation, at step 206. The LAF is configured to provide a controlled, particle-free environment by directing HEPA-filtered air over the workspace in order prevent the entry of airborne contaminants, bacteria, and unwanted microbes. By conducting inoculation in an aseptic environment, the risk of culture spoilage and competition with unwanted microorganisms is significantly reduced, thereby enhancing the reliability and reproducibility of the cultivation process.
[0017] In an example embodiment, the inoculated microalgae are cultured in outdoor conditions by utilizing natural sunlight as the primary energy source for photosynthesis, making the process cost-efficient and sustainable, at step 208. By harnessing ambient environmental conditions, the need for artificial lighting and controlled indoor setups is minimized in order to reduce energy consumption and operational costs. Outdoor cultivation may also facilitate large-scale microalgae production, making it ideal for applications such as biofuel generation, wastewater treatment, and high-value bio-product extraction in an economically viable and eco-friendly manner.
[0018] In some embodiments, the filtered DWW is used as a culture medium for microalgae cultivation using the photo-bioreactor (100). The filtered dairy wastewater (DWW) is utilized as a culture medium for microalgae cultivation in a photo-bioreactor (100), where it is blended with BG-11 media in varying ratios to optimize growth conditions. The blends comprise DWW 100 (100% DWW, 0% BG-11), DWW 80 (80% DWW, 20% BG-11), DWW 60 (60% DWW, 40% BG-11), DWW 40 (40% DWW, 60% BG-11), DWW 20 (20% DWW, 80% BG-11), and DWW 0 (0% DWW, 100% BG-11). These varying compositions allow for an evaluation of nutrient sufficiency in DWW in order to determine the optimal blend that supports maximum microalgae growth and biomass productivity. Further, utilization of DWW as a substitute for BG-11 reduces the cost of cultivation, promotes wastewater bioremediation, and enhances the sustainability of microalgae-based bioprocesses.
[0019] In some embodiments, the culture is agitated using the motorized shaking mechanism (108) at regular intervals to prevent sedimentation and ensure uniform growth. In order to maintain optimal microalgae growth, the culture in the photo-bioreactor (100) is agitated at regular intervals using a motorized shaking mechanism (108). The process of agitation may prevent sedimentation of microalgae cells in order to ensure homogeneous distribution of nutrients, light, and gases throughout the medium. Furthermore, continuous agitation enhances gas exchange, allowing efficient CO2 absorption for photosynthesis and oxygen release in order to prevent localized nutrient depletion.
[0020] In some embodiments, biomass is harvesting through at least one tap (106). The harvesting of micro-algal biomass in the photo-bioreactor (100) is facilitated through at least one tap (106) for efficient and contamination-free extraction. The at least one tap (106) is equipped with a micro-filter (0.2µm) to allow the removal of cultivated biomass while preventing the entry of unwanted contaminants. Regular harvesting through the tap (106) enables continuous monitoring of biomass growth, minimizes manual handling, and ensures easy collection of microalgae for downstream applications such as biofuel production, pigment extraction, and wastewater treatment. The automated and controlled harvesting mechanism (108) may improve process efficiency, reduces operational costs, and enhances the scalability of microalgal cultivation.
[0021] In some embodiments, the monitoring of microbial growth in the photo-bioreactor (100) is performed using UV-Vis spectroscopy to facilitate real-time observation of biomass accumulation and astaxanthin synthesis, at step 210. The technique measures the optical density (OD) of the culture at specific wavelengths, allowing quantification of microalgal growth and pigment production over time. By tracking absorbance at relevant wavelengths (e.g., 750 nm for biomass and 480–530 nm for astaxanthin), researchers may assess cell concentration, metabolic activity, and carotenoid accumulation without disrupting the culture.
[0022] Furthermore, the cultivated microalgae produce astaxanthin that is a red-colored pigment with extensive commercial applications in nutraceuticals, cosmetics, and aquaculture. The extraction process comprises multiple steps to ensure high-purity pigment recovery. First, biomass harvesting is performed using a tap (106)-integrated filtration system to collect the microalgal cells. Next, cell disruption techniques such as ultrasonication, bead milling, or enzymatic digestion are applied to break the cell walls and release intracellular astaxanthin. Finally, the solvent extraction method using solvents like acetone, ethanol, or supercritical CO2 is employed to efficiently extract and purify the pigment.
[0023] FIG. 4 illustrates a graphical representation (400) of growth of the microalgae, according to an embodiment of the present invention.
[0024] The FIG. 4 illustrates the growth curves of microalgae cultivated in different ratios of Dairy Wastewater (DWW) and BG-11 media over eight days. The biomass accumulation trends indicate that DWW supplementation significantly enhances growth as compared to BG-11 alone. The DWW 60 and DWW 40 blends exhibit the highest biomass production demonstrating an optimal nutrient balance for microalgae cultivation. Further, DWW 80 blend also shows strong growth, indicating that partially supplementing dairy wastewater with BG-11 provides sufficient nutrients. Further, the DWW 100 blend (pure dairy wastewater) shows slower growth, possibly due to the presence of inhibitory compounds or nutrient imbalances. The DWW 0 blend (pure BG-11) demonstrates the lowest growth, reinforcing that dairy wastewater acts as an effective and cost-efficient nutrient source.
[0025] The results highlight that combining dairy wastewater with BG-11 media in appropriate proportions optimizes micro-algal growth while reducing reliance on commercial culture media. The DWW 60 and DWW 40 blends appear to provide the best growth conditions, indicating that microalgae may efficiently utilize the nutrients in dairy wastewater.
[0026] FIG. 5 illustrates a tabular representation (500) of biochemical analysis of extracted pigment, according to an embodiment of the present invention.
[0027] In some embodiments, the pigment extraction is carried out using a physical method (i.e., sonication) to break open the micro algal cells and release the intracellular components. The extracted pigment is then subjected to biochemical analysis to evaluate its composition and potential applications. The total phenolic content is measured at 1.30 mg/ml, indicating the presence of antioxidant compounds that contribute to the pigment's stability and bioactivity. The total flavonoid content is high at 225.8 mg/ml, illustrating a strong potential for pharmaceutical and nutraceutical applications. Further, the carbohydrate content is determined to be 1.50 mg/ml, illustrating the presence of energy-rich biomolecules, while the protein content was found to be 0.063 g/g, indicating the presence of essential amino acids.
[0028] FIG. 6 illustrates a tabular representation (600) of a mineral analysis of the extracted pigment, according to an embodiment of the present invention.
[0029] In some embodiments, the mineral composition analysis of the extracted pigment illustrates the presence of essential nutrients. Calcium is recorded at 87.32 ± 0.071 mg/ml that is essential for cellular metabolism and structural stability. Iron, an essential component for enzymatic functions and oxygen transport that is present at 0.8025 ± 0.00 mg/ml. Further, the potassium concentration is 142.6 ± 0.57 mg/ml, highlighting its role in maintaining osmotic balance and metabolic activities. Magnesium, a vital cofactor for enzymatic reactions, is found at 33.39 ± 0.19 mg/ml. Further, the manganese is essential for antioxidant defense and enzyme activation and is present at 0.0861 ± 0.00 mg/ml. Sodium plays a key role in ion transport and cellular functions and is measured at 110.4 ± 0.99 mg/ml.
[0030] It should be noted that the astaxanthin producing photo bioreactor (100) (PBR) for microalgae cultivation, in any case could undergo numerous modifications and variants, all of which are covered by the same innovative concept; moreover, all of the details can be replaced by technically equivalent elements. In practice, the components used, as well as the numbers, shapes, and sizes of the components can be of any kind according to the technical requirements. The scope of protection of the invention is therefore defined by the attached claims.

Dated this 11th Day of March, 2025
Ishita Rustagi (IN-PA/4097)
Agent for Applicant
, C , Claims:CLAIMS
We Claim:
1. A astaxanthin producing photo bioreactor (100) (PBR) for microalgae cultivation, comprising:
a bioreactor (100) body (102) crafted with plurality of acrylic sheets (104), wherein the plurality of acrylic sheets (104) is configured to provide higher strength, flexibility, and transparency;
at least one tap (106) having a micro-filter, integrated within the bioreactor (100) body (102), wherein the at least one tap (106) enables a user daily biomass growth observation and harvesting of final product;
at least one motorized shaking mechanism (108) attached within the body (102) of bioreactor (100) for agitating algae cultures to prevent settling of culture and biomass growth.

2. A method (200) for producing astaxanthin using the photo bioreactor (100) comprising:
filtering dairy wastewater (DWW) using cellulose membrane filtration to remove undesirable particulates and impurities.
subjecting the pre-filtered DWW to vacuum filtration to the medium for enhanced microalgae growth;
using the filtered DWW as a culture medium for microalgae cultivation using the photo-bioreactor (100);
agitating the culture using the motorized shaking mechanism (108) at regular intervals to prevent sedimentation and ensure uniform growth;
harvesting biomass through at least one tap (106); and
monitoring microbial growth using UV-Vis spectroscopy to facilitate real-time observation of biomass accumulation and astaxanthin (i.e., pigment) synthesis.

3. The method (200) as claimed in claim 1, wherein the culture medium comprises a blend of dairy wastewater (DWW) with BG-11 media at different ratios.
4. The method (200) as claimed in claim 1, wherein the microalgae strain used corresponds to Scenedesmus abundans.
5. The method (200) as claimed in claim 1, wherein the filtered DWW media is inoculated under laminar airflow (LAF) conditions to ensure sterility and minimizing contamination risk.
6. The method (200) as claimed in claim 1, wherein the inoculated microalgae are cultured in outdoor conditions leading to cost-efficient biomass production by means of natural sunlight for photosynthesis.
7. The method (200) as claimed in claim 1, wherein cultivated microalgae produce astaxanthin, a red-colored pigment which is extracted for commercial applications.
8. The method (200) as claimed in claim 1, wherein the extraction process of astaxanthin comprises biomass harvesting, cell disruption, and solvent extraction, yielding a high-purity pigment.
9. The method (200) as claimed in claim 1, wherein the extracted pigment is subjected to biochemical analysis, and mineral analysis.

Dated this 11th Day of March, 2025
Ishita Rustagi (IN-PA/4097)
Agent for Applicant