Global climate change has emerged as a pressing global issue in contemporary times. The primary contributors to this phenomenon are the rising levels of greenhouse gases, predominantly originating from human activities and the operations of power plants (Watanabe Y, et., al; 2017).

Human activities, such as fossil fuel usage and industrial production, as well as natural processes involving the Earth’s oceans, soil, plants, animals, and volcanoes, release greenhouse gases, including CO_2, CH₄, and N₂O, into the atmosphere. However, since the Industrial Revolution, human activities have emerged as the primary contributors to greenhouse gas emissions (Baba Mohammad et al., 2015; Mirzaei et al., 2015).

Specific Sources of CO₂ Emissions

According to Le Quere (Le Quere et al. 2013, 2015), the combustion of fossil fuels, namely coal, natural gas, and oil, is responsible for about 87% of human-produced CO₂ emissions. Among these fuels, coal combustion contributes to 43% of CO₂ emissions from fuel burning, followed by oil at 36% and natural gas at 20%. Power plants, vehicles, aircraft, and industrial facilities primarily use these fossil fuels to generate heat, electricity, and power. The largest share of man-made CO₂ emissions, approximately 41%, originates from power generation and heating activities. Transportation ranks as the second largest source, accounting for around 22% of CO₂ emissions resulting from fossil fuel burning. Industries contribute approximately 20% of CO₂ emissions from fossil fuel combustion. Other human-related sources include deforestation and land-use changes, contributing to roughly 9%, and industrial processes like cement manufacturing, which account for around 4%.

The emission of CO₂ into the atmosphere involves not only human activities but also natural processes. According to a study conducted by Denman et al. In 2007, researchers found that natural sources significantly contribute to CO2 emissions. The Earth’s oceans, through the exchange between the ocean and the atmosphere, account for a substantial 42.84% of these natural emissions. Additionally, sources like plant and animal respiration, soil respiration, and decomposition contribute to 28.56% of the total CO₂ emissions generated naturally.

CO₂: A major Green House Gas

Research efforts are ongoing and focused on tackling global warming by actively mitigating greenhouse gas emissions. While carbon dioxide naturally exists as a greenhouse gas, the concentration of CO₂ in the atmosphere has undergone a substantial increase because of industrialization and human activities (National Research Council et al.,2011; Siegenthaler U et al., 2005; Chang EH et al, 2003).

According to a report by the French National Center for Scientific Research, atmospheric CO₂ levels have soared to 380 parts per million (ppm), marking a twofold increase compared to the previous century (Morais and Costa, et al.,2007). The notable surge in CO₂ concentration directly attributes to the combination of population growth and industrialization. Future projections indicate that by 2100, CO₂ emissions in the atmosphere could reach a staggering 26 billion tons, surpassing the emissions recorded in the past century by 18.5 billion tons (Chiu et al., 2008).

Power plants play a significant role in releasing CO₂ into the atmosphere through the combustion of fossil fuels (Benemann JR et al., 1993). To tackle the challenge of CO₂ emissions from this source, it is imperative to prioritize efforts in enhancing the efficiency of power plant generation and transitioning towards cleaner and more sustainable alternatives.

Biological CO₂ Sequestration Technology/Method

In 1990, the Research Institute of Innovative Technology for the Earth (RITE) launched the Biological CO₂ Fixation and Utilization Project under the sponsorship of the Ministry of International Trade and Industry (MITI). The New Energy and Industrial Technology Development Organization (NEDO) commissioned this pioneering initiative (Murakami, N, et al., 1996).

Among the array of available CO₂ capture methods, the biological approach stands out as an attractive alternative. This approach harnesses the power of photosynthesis, which enables the conversion of carbon dioxide into organic matter, fueled by sunlight as an energy source. In this regard, photosynthetic microorganisms have emerged as a preferred choice, owing to their remarkable characteristics. These microorganisms possess the unique ability to assimilate CO₂ into carbohydrates, lipids, and proteins using solar energy. They exhibit higher rates of CO₂ fixation compared to land plants and offer better compatibility for integrating CO₂ removal systems into industrial processes when compared to other photosynthetic systems involving higher plants.

Algae potential players for CO₂ Sequestration.

Within the realm of photosynthesis, there are two fundamental processes at play: the light-dependent reaction, which entails a series of intricate steps reliant on the availability of light, and the light-independent reaction, also recognized as carbon fixation. In the context of microalgae, they have developed a specialized mechanism known as the CO₂ concentrating mechanism (CCM) to secure an ample reservoir of inorganic carbon required to support cellular growth and proliferation during the process of photosynthesis (Brueggeman et al., 2012).

The CO₂ concentrating mechanism (CCM) plays a crucial role in microalgae by effectively increasing the concentration of CO₂ at the active site of the enzyme Rubisco (ribulose-1,5-bisphosphate carboxylase oxygenase). These microorganisms possess specialized inorganic carbon transporters located in the plasma membrane and thylakoid membrane, each with varying affinities and flux rates for HCO₃ (bicarbonate) and CO₂ (Beardall and Raven, 2017). Carbonic anhydrase (CA) is responsible for converting HCO₃ into CO₂, and the proper functioning of both CA and the CCM is highly dependent on the availability of CO₂ (Zou et al., 2004; Zhou et al., 2016) See Fig 1.

As a result, the availability of CO2 intricately ties to the activity of these enzymes. While elevated CO₂ levels can promote the growth of algae, they may also impede the activity of carbonic anhydrase (CA) and the functioning of the CO₂ concentrating mechanism (CCM) (Xia and Gao, 2005).

Microalgae surpass terrestrial plants in their efficiency in converting CO₂ into organic compounds. They exhibit approximately 10 times greater efficacy in CO₂ fixation compared to land plants.

Algae cultivation in Wastewater an alternative approach for wastewater treatment & CO₂ Sequestration.

The combination of biological CO₂ fixation using microalgae and wastewater treatment presents significant advantages in terms of both economic feasibility and environmental sustainability. By cultivating microalgae in nutrient-rich wastewater, these microorganisms have ample access to the nutrients needed for their growth. As they flourish, microalgae absorb CO₂ and convert it into biomass, which can be utilized as a valuable feedstock for biofuel production (Kannan DC et., 2022, Magar et al., 2022).

The integration of CO₂ capture, wastewater treatment, and biofuel production creates a synergistic and compelling approach. It not only contributes to reducing CO₂ emissions by capturing and utilizing CO₂ but also addresses the crucial requirement for effective wastewater treatment. This combined strategy demonstrates a promising solution that not only helps mitigate climate change but also promotes the efficient utilization of resources while generating a valuable end product (Wang B et al., 2008).

The integration of microalgae in wastewater treatment presents a sustainable and eco-conscious solution that minimizes or eliminates the requirement for chemical treatments in wastewater plants. This groundbreaking technology utilizes the inherent abilities of microalgae to effectively extract nutrients, specifically nitrogen and phosphorus compounds, from wastewater. In addition to facilitating CO₂ capture through photosynthesis, this approach successfully tackles the pressing challenge of nutrient removal in wastewater.

Mechanism of Microalgae-based Wastewater Treatment

Microalgae offer an invaluable solution to address the challenge of microcontaminants found in wastewater effluents, which can pose significant risks when they enter drinking water treatment processes (Beelen ES et al., 2007). By efficiently eliminating these microcontaminants, microalgae greatly improve the overall quality of water. Additionally, microalgae play a vital role in reducing nutrient levels, such as carbon, nitrogen, and phosphorus, while simultaneously releasing significant amounts of oxygen. This dual action not only aids in the decomposition of organic matter by bacteria but also helps mitigate odor-related issues commonly associated with wastewater (De Pauw N et al., 1983).

The abundant availability of nutrients in municipal wastewater makes it an ideal resource for harnessing the potential of microalgae. Furthermore, the close proximity of wastewater treatment plants to power plants, which generate significant amounts of CO₂ in flue gases through the combustion of fossil fuels, further emphasizes the benefits of this approach. This strategic positioning enables the efficient utilization of readily available CO₂ resources.

Microalgae cultivation in wastewater presents versatile opportunities, allowing for the use of either open or closed systems. These approaches enable precise control over the growth media, optimizing the removal of nutrients from wastewater and maximizing the production of valuable microalgae biomass. This customized approach ensures effective and sustainable wastewater treatment while generating valuable resources in the form of microalgae biomass.

Open ponds

High-rate algal ponds, commonly known as HRAPs or raceway ponds, are the prevailing large-scale production systems in practice. These open, shallow ponds have been employed since the 1950s and utilize a paddle wheel to ensure the circulation of algae and nutrients. While raceway ponds are relatively affordable to construct and operate, their productivity is often hindered by challenges such as contamination, inadequate mixing, the presence of dark zones, and inefficient utilization of CO₂ (Chisti, 2007; Mata et al., 2010).

In theory, raceway ponds should achieve production levels of 50–60 g m−2 day−1, and there have been instances of reaching such levels in a single day (Sheehan et al., 1998). However, in practical applications, it proves difficult to attain even 10–20 g m−2 day−1 productivity (Shen et al., 2009). While the high evaporation rate of open ponds is often perceived as a limitation, it does provide some benefits by aiding in temperature regulation through evaporative cooling (U.S. DOE, 2010).

Moreover, the HRP system’s simplicity and symbiotic nature make it a perfect candidate for emulating natural ecosystems in laboratory and field settings, aligning harmoniously with the principles of ecological engineering (Cunningham M et al., 2010).

An important conclusion drawn from cost analysis studies conducted by the U.S. Department of Energy’s Aquatic Species Program was that there are limited prospects for alternative systems to replace the open pond approach, particularly when considering the need for low fuel costs (Sheehan et al., 1998).

Closed reactors

According to Chisti (2007), tubular photobioreactors are the exclusive type of closed systems used on a large scale. These reactors come in vertical, horizontal, and helical designs, with helical ones being regarded as the easiest to expand (Carvalho et al., 2006). In comparison to open ponds, tubular photobioreactors offer several advantages such as improved control over pH and temperature, better protection against contamination, enhanced mixing, reduced evaporation, and higher cell densities (Mata et al., 2010).

Reported productivities typically range from 20 to 40 grams per square meter per day (Shen et al., 2009). However, despite these benefits, tubular reactors have not gained significant usage due to various challenges. Issues such as the accumulation of toxic oxygen, unfavorable pH and CO₂ gradients, overheating, bio-fouling, and high material and maintenance costs have limited their widespread adoption (Mata et al., 2010; Molina Grima et al., 1999). Among these challenges, the removal of oxygen is considered one of the most difficult problems to overcome, particularly when scaling up the system. It effectively imposes limitations on the length of tubes or panels and necessitates a more complex or modular design (Carvalho et al., 2006

How Algae CO₂ Sequestration Potential is Calculated?

To tackle the challenge of reducing CO₂ emissions, researchers have explored various avenues, which can be broadly divided into two groups: (i) methods based on chemical reactions and (ii) biological methods (Benemann JR et al., 1993, Wang B et al.,2008). Among these, biological processes have emerged as compelling solutions to combat global warming, attracting significant attention from the scientific community (Yun YS et al., 1997).

Chisti emphasizes that microalgal biomass typically consists of around 50% carbon, allowing for the capture of approximately 1.83 kg of CO₂ per kilogram of biomass produced (Chisti et al., 2007). In the field of CO₂ capture using microalgae, many studies rely on measuring CO₂ concentrations at the inlet and outlet of cultivation reactors. However, this approach may pose challenges as it does not guarantee that all consumed CO₂ is solely attributed to the growth of microalgae. Alternatively, estimating the carbon content can provide a more precise assessment of the CO₂ consumption by microalgae cells, assuming that the culture medium does not contain carbon sources other than CO₂ (Yun YS et al., 1997; Tang D et al., 2011).

Based on this premise, researchers can estimate the rate of CO₂ capture (RCO₂) using the following formula.

RCO₂ = P·CCO₂·MCO₂/MC,

 where P represents biomass productivity (g L-1 day-1), CCO₂ denotes the carbon content of microalgae biomass obtained from CO₂, and MCO₂ and MC correspond to the molecular weights of carbon dioxide and carbon, respectively.

CO₂ concentration and CO₂ uptake efficiency of Microalgae

The cultivation of photoautotrophic microalgae relies on carbon dioxide (CO₂) as the primary source of carbon. Despite the physiological significance of CO₂ concentration on microalgae cell growth, researchers have conducted limited research to analyze CO₂ uptake under relevant process conditions, indicating the need for further investigation (Cheng L et al., 2006). Atmospheric air contains minimal amounts of CO₂, which cannot sufficiently support microalgae cell growth due to limited mass transfer driving forces. To overcome this challenge, researchers can obtain CO₂ from pure sources or harness it from flue gases, thereby addressing the environmental concern associated with CO₂ capture (Acién Fernández FG et al., 2012).

Microalgae and cyanobacteria have the ability to adapt their photosynthetic properties, including the carbon concentrating mechanism (CCM), to high concentrations of CO₂ (Baba et al., 2011). Certain microalgae and cyanobacteria species, such as Chlamydomonas reinhardtii, can quickly acclimate to a CO₂ concentration of 20% within a few days (Hanawa et al., 2007).

When developed at air-equilibrated CO₂ levels, microalgae and cyanobacteria can effectively utilize low levels of dissolved inorganic carbon (DIC). Cyanobacteria actively increase calcite deposition at higher CO₂ concentrations, which plays a crucial role in CO₂ removal. This increase leads to a 1.5- to 2.5-fold enhancement in CO₂ fixation rates (Ramanan et al., 2009, 2010; Badger and Price, 1994).

Enhancing CO₂ Mass Transfer with Microbubbles

Some of the important physical factors that change the mass transfer rate of CO₂ from the air to liquid are air bubble size, the pore size of the sparger, flow rate, air holding time of the liquid system, etc. Microbubble size is a very essential aspect to enhance the CO₂ mass transfer rate (McGinn PJ et al., 2011). However, high CO₂ concentrations hinder the growth of microalgae and cyanobacteria (Ramanan et al., 2010).

Previous research has reported that optimal CO₂ fixation occurs at concentrations ranging from 2% to 5% CO₂, with 3% CO₂ being approximately 489 times higher than the atmospheric CO₂concentration (Douskova et al., 2009; Ibn-Mohammed et al., 2013). These studies indicate that many algal strains may not require undermined haphazard high CO₂ feeding. Excess-supplied CO₂ mostly goes to waste, and it is necessary to determine the critical CO₂ concentration required by each strain.(Chaitanya Magar et al. 2019, Rambhiya, S. J. et al 2021).

Conclusion

In summary, the utilization of microalgae cultures presents a promising solution for both CO₂ capture and biomass production. By cultivating microalgae in wastewater media, it becomes possible to remove significant pollutants from the wastewater while efficiently capturing CO₂ and converting it into valuable biomass feedstock. The selection of suitable algae strains and optimization of key parameters such as pH, temperature, and CO₂ concentration is crucial in maximizing CO₂ fixation efficiency in biological systems. Certain algae species, such as Scenedesmus dimorphus, Scenedesmus incrassatulus, Chlorella sp., and Scenedesmus obliquus, demonstrate remarkable CO₂ fixation rates.

Moreover, integrating CO₂ capture from flue gases with microalgae-based wastewater treatment holds immense potential for sustainable biofuel production. This integrated approach offers the opportunity to address environmental concerns by capturing CO₂ emissions, treating wastewater, and producing valuable biofuel resources concurrently. To enhance the efficiency and effectiveness of microalgae cultivation, the development of comprehensive dynamic models becomes essential. These models should accurately depict the growth rates of microalgae under various limiting factors, enabling the design of optimized control systems and the identification of optimal operational conditions.

By advancing our understanding of the complex interactions and dynamics involved in microalgae-based systems, we can unlock the full potential of this technology. Ultimately, this will contribute to reducing reliance on fossil fuels, mitigating CO₂ emissions, and promoting a more sustainable and environmentally friendly approach to energy and wastewater management.

References:

Razzak SA, Ali SA, Hossain MM, deLasa H. Biological CO₂ fixation with production of microalgae in wastewater–a review. Renewable and Sustainable Energy Reviews. 2017 Sep 1;76:379-90.

Babamohammadi S, Shamiri A, Aroua MK. A review of CO₂ capture by absorption in ionic liquid-based solvents. Reviews in Chemical Engineering. 2015 Aug 1;31(4):383-412.

Le Quéré C. C., Andres, RJ, Boden, T., Conway, T.

Le Quéré C, Moriarty R, Andrew RM, Canadell JG, Sitch S, Korsbakken JI, Friedlingstein P, Peters GP, Andres RJ, Boden TA, Houghton RA. Global carbon budget 2015. Earth System Science Data. 2015 Dec 7;7(2):349-96.

Menon S, Denman KL, Brasseur G, Chidthaisong A, Ciais P, Cox PM, Dickinson RE, Hauglustaine D, Heinze C, Holland E, Jacob D. Couplings between changes in the climate system and biogeochemistry. Lawrence Berkeley National Lab.(LBNL), Berkeley, CA (United States); 2007 Oct 1.

National Research Council. Advancing the science of climate change. National Academies Press; 2011 Jan 10.

Siegenthaler U, Stocker TF, Monnin E, Luthi D, Schwander J, Stauffer B, Raynaud D, Barnola JM, Fischer H, Masson-Delmotte V, Jouzel J. Stable carbon cycle climate relationship during the Late Pleistocene. Science. 2005 Nov 25;310(5752):1313-7.

Chang EH, Yang SS. Some characteristics of microalgae isolated in Taiwan for biofixation of carbon dioxide. Botanical Bulletin of Academia Sinica. 2003;44.

De Morais MG, Costa JA. Biofixation of carbon dioxide by Spirulina sp. and Scenedesmus obliquus cultivated in a three-stage serial tubular photobioreactor. Journal of biotechnology. 2007 May 1;129(3):439-45.

Chiu SY, Kao CY, Chen CH, Kuan TC, Ong SC, Lin CS. Reduction of CO₂ by a high-density culture of Chlorella sp. in a semicontinuous photobioreactor. Bioresource technology. 2008 Jun 1;99(9):3389-96.

Benemann JR. Utilization of carbon dioxide from fossil fuel-burning power plants with biological systems. Energy conversion and management. 1993 Sep 1;34(9-11):999-1004.

References:

Murakami,M., N.Yamaguchil H.Murakami, T.Nishide, T.Muranaka, F.Yamada and Y.Takimoto (1996). Over-expression of carbonic anhydrase and its localization in carboxysome in cyanobacteria Synechococcus sp. PCC7942. Abstract Paper at the annual meeting of the Societ) for Fermentation and Bioengineering Japan. No. 1059.

Brueggeman AJ, Gangadharaiah DS, Cserhati MF, Casero D, Weeks DP, Ladunga I. Activation of the carbon concentrating mechanism by CO₂ deprivation coincides with massive transcriptional restructuring in Chlamydomonas reinhardtii. The Plant Cell. 2012 May;24(5):1860-75.

Beardall J, Raven JA. Cyanobacteria vs green algae: which group has the edge?. Journal of Experimental Botany. 2017 Jun 22;68(14):3697-9.

Zhou W, Sui Z, Wang J, Hu Y, Kang KH, Hong HR, Niaz Z, Wei H, Du Q, Peng C, Mi P. Effects of sodium bicarbonate concentration on growth, photosynthesis, and carbonic anhydrase activity of macroalgae Gracilariopsis lemaneiformis, Gracilaria vermiculophylla, and Gracilaria chouae (Gracilariales, Rhodophyta). Photosynthesis Research. 2016 Jun;128:259-70.

Kannan DC, Magar CS. Microalgal biofuels: Challenges, status and scope. InAdvanced Biofuel Technologies 2022 Jan 1 (pp. 73-118). Elsevier.

XIA JR, GAO KS. Impacts of elevated CO₂ concentration on biochemical composition, carbonic anhydrase, and nitrate reductase activity of freshwater green algae. Journal of Integrative Plant Biology. 2005 Jun;47(6):668-75.

Wang B, Li Y, Wu N, Lan CQ. CO₂ bio-mitigation using microalgae. Applied microbiology and biotechnology. 2008 Jul;79:707-18.

Beelen ES. Municipal wastewater treatment plant (WWTP) effluents: a concise overview of the occurrence of organic substances. Association of River Waterworks-RIWA; 2007.

De Pauw N, Van Vaerenbergh E. Microalgal wastewater treatment systems: potentials and limits. Phytodepuration and the Employment of the Biomass Produced. Centro Ric. Produz, Animali, Reggio Emilia, Italy. 1983:211-87.

Chisti Y. Biodiesel from microalgae. Biotechnology advances. 2007 May 1;25(3):294-306.

Mata TM, Martins AA, Caetano NS. Microalgae for biodiesel production and other applications: a review. Renewable and sustainable energy reviews. 2010 Jan 1;14(1):217-32.

References:

Sheehan J, Dunahay T, Benemann J, Roessler P. Look back at the US department of energy’s aquatic species program: biodiesel from algae; close-out report. National Renewable Energy Lab., Golden, CO.(US); 1998 Jul 1.

Doe US. National algal biofuels technology roadmap. US Department of Energy, Office of Energy Efficiency and Renewable Energy, Biomass Program. 2010 May.

Cunningham M, Heim C, Rauchenwald V. Algae production in wastewater treatment: prospects for Ballen. LoCal-RE Summer Research Program. 2010 Aug 26;15.

Carvalho AP, Meireles LA, Malcata FX. Microalgal reactors: a review of enclosed system designs and performances. Biotechnology progress. 2006;22(6):1490-506.

Fernández FA, Camacho FG, Chisti Y. Photobioreactors: light regime, mass transfer, and scaleup. InProgress in industrial microbiology 1999 Jan 1 (Vol. 35, pp. 231-247). Elsevier.

Shen Y, Yuan W, Pei ZJ, Wu Q, Mao E. Microalgae mass production methods. Transactions of the ASABE. 2009;52(4):1275-87.

Yun YS, Lee SB, Park JM, Lee CI, Yang JW. Carbon dioxide fixation by algal cultivation using wastewater nutrients. Journal of Chemical Technology & Biotechnology: International Research in Process, Environmental and Clean Technology. 1997 Aug;69(4):451-5.

Tang D, Han W, Li P, Miao X, Zhong J. CO₂ biofixation and fatty acid composition of Scenedesmus obliquus and Chlorella pyrenoidosa in response to different CO₂ levels. Bioresource technology. 2011 Feb 1;102(3):3071-6.

Cheng L, Zhang L, Chen H, Gao C. Carbon dioxide removal from air by microalgae cultured in a membrane-photobioreactor. Separation and purification technology. 2006 Jul 15;50(3):324-9.

Acién Fernández FG, González-López CV, Fernández Sevilla JM, Molina E. Conversion of CO 2 into biomass by microalgae: how realistic a contribution may it be to significant CO₂ removal?. Applied microbiology and biotechnology. 2012 Nov;96:577-86.

Baba M, Suzuki I, Shiraiwa Y. Proteomic analysis of high CO₂ inducible extracellular proteins in the unicellular green alga, Chlamydomonas reinhardtii. Plant and cell physiology. 2011 Aug 1;52(8):1302-14.

References:

Hanawa, Y., 2007. Study on a CO₂ Sensing Mechanism by the Expression Analysis of a High CO₂ Inducible H43 Gene In Chlamydomonas reinhardtii.

Ramanan R, Kannan K, Vinayagamoorthy N, Ramkumar KM, Sivanesan SD, Chakrabarti T. Purification and characterization of a novel plant-type carbonic anhydrase from Bacillus subtilis. Biotechnology and Bioprocess Engineering. 2009 Feb;14:32-7.

Ramanan R, Kannan K, Deshkar A, Yadav R, Chakrabarti T. Enhanced algal CO₂ sequestration through calcite deposition by Chlorella sp. and Spirulina platensis in a mini-raceway pond. Bioresource technology. 2010 Apr 1;101(8):2616-22.

Badger MR, Price GD. The role of carbonic anhydrase in photosynthesis. Annual review of plant biology. 1994 Jun;45(1):369-92.

McGinn PJ, Dickinson KE, Bhatti S, Frigon JC, Guiot SR, O’Leary SJ. Integration of microalgae cultivation with industrial waste remediation for biofuel and bioenergy production: opportunities and limitations. Photosynthesis research. 2011 Sep;109:231-47.

Douskova I, Doucha J, Livansky K, Machat J, Novak P, Umysova D, Zachleder V, Vitova M. Simultaneous flue gas bioremediation and reduction of microalgal biomass production costs. Applied microbiology and biotechnology. 2009 Feb;82:179-85.

Ibn-Mohammed T, Greenough R, Taylor S, Ozawa-Meida L, Acquaye A. Operational vs. embodied emissions in buildings—A review of current trends. Energy and Buildings. 2013 Nov 1;66:232-45.

Rambhiya, S. J., Magar, C. S., & Deodhar, M. A. (2021). Using seawater-based Na₂CO₃ medium for scrubbing the CO₂ released from Bio-CNG plant for enhanced biomass production of Pseudanabaena limnetica. SN Applied Sciences, 3(2), 1-17. (Link – https://link.springer.com/article/10.1007/s42452-021-04271-7)

Chaitanya Magar, Sagar Rambhiya and Manjushri Deodhar, 2019. Evaluation of CO₂ Removal Efficiency of Pseudanabaena limnetica (Lemm.) Komárek Grown in Na₂CO₃ Enriched Seawater Medium in 60 L Airlift Flat Panel Photobioreactor. Journal of Environmental Science and Technology, 12: 186-196. DOI: 10.3923/jest.2019.186.196 (URL: https://scialert.net/abstract/?doi=jest.2019.186.196)