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Cited by 99Algal biology and biofuel productionMicrobial Metabolic Engineering and BioproductionBioeconomy and Sustainability Development

A Holistic Approach to Circular Bioeconomy Through the Sustainable Utilization of Microalgal Biomass for Biofuel and Other Value-Added Products

Open access
Ezhumalai, Ganesan, Arun, Muthukrishnan, Manavalan, Arulmani, Rajkumar, Renganathan, Heese, Klaus·2024·Microbial Ecology
DOI 10.1007/s00248-024-02376-1PMC PMC11045622
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Abstract

Emissions from transportation and industry primarily cause global warming, leading to floods, glacier melt, and rising seas. Widespread greenhouse gas emissions and resulting global warming pose significant risks to the environment, economy, and society. The need for alternative fuels drives the development of third-generation feedstocks: microalgae, seaweed, and cyanobacteria. These microalgae offer traits like rapid growth, high lipid content, non-competition with human food, and growth on non-arable land using brackish or waste water, making them promising for biofuel. These unique phototrophic organisms use sunlight, water, and carbon dioxide (CO 2 ) to produce biofuels, biochemicals, and more. This review delves into the realm of microalgal biofuels, exploring contemporary methodologies employed for lipid extraction, significant value-added products, and the challenges inherent in their commercial-scale production. While the cost of microalgae bioproducts remains high, utilizing wastewater nutrients for cultivation could substantially cut production costs. Furthermore, this review summarizes the significance of biocircular economy approaches, which encompass the utilization of microalgal biomass as a feed supplement and biofertilizer, and biosorption of heavy metals and dyes. Besides, the discussion extends to the in-depth analysis and future prospects on the commercial potential of biofuel within the context of sustainable development. An economically efficient microalgae biorefinery should prioritize affordable nutrient inputs, efficient harvesting techniques, and the generation of valuable by-products. Graphical Abstract:

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TL;DR

This review argues that microalgal biomass can support a circular bioeconomy by coupling wastewater-based cultivation with biofuel production and valorization of de-oiled residues into feed, fertilizer, and biosorbents. It synthesizes lipid extraction, genetic engineering, biorefinery, and techno-economic/LCA challenges, concluding that commercial viability still depends on cheaper nutrients, efficient harvesting, and high-value by-products.

Key findings

  • Microalgae can produce oil yields 5–20 times higher than palm oil on an equal area basis, and biodiesel from microalgae oil can reduce CO₂ emissions by 78%; biomethane yields from microalgal biomass ranged from 140 to 380 mL CH₄/g volatile solids.
  • Lipid-extracted/de-oiled microalgal biomass can be valorized into bioethanol, biohydrogen, biomethane, biofertilizer, animal feed, and biosorbents; examples include up to 7.5% replacement of feed ingredients for pigs and poultry, up to 10% fishmeal/soy protein replacement for juvenile red drum, and 86% methylene blue removal within 24 h by Microspora sp. de-oiled biomass.
  • Techno-economic estimates show one tonne of algae costing $150–$6,000, biodiesel costs of $8.52–$18.10 per gallon from open ponds and $9.84–$20.53 per gallon from photobioreactors, and $2.80 per liter for 10,000 tonnes of microalgae with 30% lipids; genetically modified strains in fully lined open raceway ponds may cost up to 25% more than unlined counterparts, with air-supported greenhouse ponds estimated at $60,000 per hectare.
  • Biofertilizer potential includes Arthrospira sp. containing 6.70% N, 2.47% P, and 1.14% K; heavy-metal biosorption examples include Chlorella removing 65% of Cd at 5.62 mg Cd/L and Scenedesmus/Chlorella removing 48%/31% of 20 mg Cr/L.

Methods

  • Narrative review synthesizing contemporary literature on microalgal biofuels, lipid extraction methods, value-added products, genetic engineering, feed/fertilizer/biosorbent applications, and circular biorefinery approaches.
  • No primary experimental sample or new dataset is reported; the paper compiles and discusses prior studies and includes summary tables on microalgal biochemical content, lipid-extracted biomass utilization, and genetic engineering techniques.
  • Main analysis is qualitative synthesis, with techno-economic and life-cycle assessment findings cited from prior studies rather than newly modeled.

Limitations

  • The paper states that high production costs, scalability limits, lipid-extraction constraints, resource availability, regulatory/policy barriers, environmental concerns, market acceptance, R&D gaps, infrastructure integration, and long-term sustainability issues impede commercial microalgal biofuel adoption.
  • It also states that most wastewater-microalgae research remains lab-scale, with only a few pilot studies, and that more real-world practicality, economics, and LCA work are needed.
  • Evident from the text: as a narrative review, it does not describe a systematic search strategy, inclusion criteria, or meta-analysis, and many quantitative claims are drawn from secondary cited studies without independent validation.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1007/s00248-024-02376-1

Cites

140 of 140 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

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  • Premisecitation

    Microalgae can produce direct combustion crude algal oil for transportation fuels and biodiesel through solvent extraction and trans-esterification.

    “Microalgae can produce direct combustion crude algal oil for transportation fuels and biodiesel through solvent extraction and trans-esterification [15].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [15] Chisti Y (2007) Biodiesel from microalgae. Biotechnol Adv 25:294–306 source

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    Anaerobic processes like biohydrogen production, biogas digestion, and bioethanol generation can utilize microalgae.

    “Anaerobic processes like biohydrogen production, biogas digestion, and bioethanol generation can utilize microalgae [2].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Bhattacharya S, Maurya R, Mishra SK, Ghosh T, Patidar SK, Paliwal C, Chokshi K, Pancha I, Maiti S, Mishra S (2016) Solar driven mass cultivation and the extraction of lipids from Chlorella variabilis: a case study. Algal Res 14:137–142 source

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    Microalgae have significant potential as biological resources in industries like medicine, healthcare, feed, and fuel.

    “Microalgae have significant potential as biological resources in industries like medicine, healthcare, feed, and fuel.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [4] Purohit P, Chaturvedi V (2018) Biomass pellets for power generation in India: a techno-economic evaluation. Environ Sci Pollut Res 25:29614–29632. https://doi.org/10.1007/s11356-018-2960-8 source

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  • Premisecitation

    Aquatic algae have potential as a valuable feedstock for bioproducts due to their ability to capture carbon and remove nitrogen and phosphorus from wastewater.

    “Aquatic algae, found in freshwater, brackish, spring, and salt lake habitats, have potential as a valuable feedstock for bioproducts due to their ability to capture carbon and remove nitrogen (N) and phosphorus (P) from wastewater [6, 7].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [6] Barsanti L, Gualtieri P (2022) Algae: anatomy, biochemistry, and biotechnology. CRC press

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    • cites [7] Nishshanka GKSH, Anthonio RADP, Nimarshana PHV, Ariyadasa TU, Chang J-S (2022) Marine microalgae as sustainable feedstock for multi-product biorefineries. Biochem Eng J 187:108593 source

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  • Premisecitation

    Large-scale production of genetically modified algal biomass (fourth generation biofuel) is confronted by hurdles including ecological risks, high production costs, concerns about legitimacy, and suboptimal growth rates.

    “The realization of large-scale production of genetically modified (GM) algal biomass, referred to as fourth generation biofuel (FGB), is confronted by several hurdles including ecological risks, high production costs, concerns about legitimacy, and suboptimal growth rates, among other factors [20, 21].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [20] Abdullah B, Muhammad SA, Shokravi Z, Ismail S, Kassim KA, Mahmood AN, Aziz MM (2019) Fourth generation biofuel: a review on risks and mitigation strategies. Renew Sust Energ Rev 107:37–50. https://doi.org/10.1016/j.rser.2019.02.018 source

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    • cites [21] Leong W-H, Lim J-W, Lam M-K, Uemura Y, Ho Y-C (2018) Third generation biofuels: a nutritional perspective in enhancing microbial lipid production. Renew Sust Energ Rev 91:950–961. https://doi.org/10.1016/j.rser.2018.04.066 source

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    Premisecitation

    Eco-friendly technologies have reduced India's reliance on fossil fuels for power generation from 68 to 63.05%.

    “Eco-friendly technologies have reduced India’s reliance on fossil fuels for power generation from 68 to 63.05% [4].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4] Purohit P, Chaturvedi V (2018) Biomass pellets for power generation in India: a techno-economic evaluation. Environ Sci Pollut Res 25:29614–29632. https://doi.org/10.1007/s11356-018-2960-8 source

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    Premisecitation

    Global greenhouse gas emissions, primarily CO2, are projected to rise by 1.3% per year between 2005 and 2011.

    “However, this shift has increased global greenhouse gas emissions, primarily CO2, which are projected to rise by 1.3% per year between 2005 and 2011 [1, 5].”
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    • cites [1] Kothari R, Ahmad S, Pathak VV, Pandey A, Kumar A, Shankarayan R, Black PN, Tyagi VV (2021) Algal-based biofuel generation through flue gas and wastewater utilization: a sustainable prospective approach. Biomass Convers Biorefinery 11:1419–1442. https://doi.org/10.1007/s13399-019-00533-y source

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    • cites [5] Kadir WNA, Lam MK, Uemura Y, Lim JW, Lee KT (2018) Harvesting and pre-treatment of microalgae cultivated in wastewater for biodiesel production: a review. Energy Convers Manag 171:1416–1429. https://doi.org/10.1016/j.enconman.2018.06.074 source

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    Microalgae offer rapid growth, high photosynthetic efficiency, high biomass production, and high lipid content, requiring less land area and not competing with food sources.

    “They offer rapid growth, high photosynthetic efficiency, high biomass production, and a high lipid content, requiring less land area and not competing with food sources [12].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [12] Vo HNP, Ngo HH, Guo W, Nguyen TMH, Liu Y, Liu Y, Nguyen DD, Chang SW (2019) A critical review on designs and applications of microalgae-based photobioreactors for pollutants treatment. Sci Total Environ 651:1549–1568 source

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    Premisecitation

    Greenhouse gas emissions from industrial and transportation activities cause global warming, flooding, glacier melting, and rising sea levels.

    “Global warming, flooding, glacier melting, and rising sea levels are outcomes of greenhouse gas emissions from industrial and transportation activities.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Kothari R, Ahmad S, Pathak VV, Pandey A, Kumar A, Shankarayan R, Black PN, Tyagi VV (2021) Algal-based biofuel generation through flue gas and wastewater utilization: a sustainable prospective approach. Biomass Convers Biorefinery 11:1419–1442. https://doi.org/10.1007/s13399-019-00533-y source

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    Premisecitation

    Population growth and improved living standards have increased consumption of natural resources like wood, oil, and water, leading to water and air pollution from various sectors.

    “Population growth and improved living standards have increased the consumption of natural resources like wood, oil, and water, leading to water and air pollution from various sectors [3].”
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    • cites [3] Banu JR, Kavitha S, Gunasekaran M, Kumar G (2020) Microalgae based biorefinery promoting circular bioeconomy-techno economic and life-cycle analysis. Bioresour Technol 302:122822 source

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    Premisecitation

    Microalgal oil can be converted into biodiesel, with higher productivity per acre of land than conventional feedstocks, utilizing marginal water sources like wastewater and agricultural runoff.

    “Microalgal oil can be converted into biodiesel, with higher productivity per acre of land than conventional feedstocks, utilizing marginal water sources like wastewater and agricultural runoff [13].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [13] Maurya R, Chokshi K, Ghosh T, Trivedi K, Pancha I, Kubavat D, Mishra S, Ghosh A (2016) Lipid extracted microalgal biomass residue as a fertilizer substitute for Zea mays L. Front Plant Sci 6. https://doi.org/10.3389/fpls.2015.01266 source

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    Premisecitation

    Microalgae can grow in marginal terrain using water sources unsuitable for agriculture, with a potential oil yield 5-20 times higher than palm oil on an equal area basis.

    “Microalgae can grow in marginal terrain using water sources unsuitable for agriculture, with a potential oil yield 5–20 times higher than palm oil on an equal area basis [14].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] Rodolfi L, Chini Zittelli G, Bassi N, Padovani G, Biondi N, Bonini G, Tredici MR (2009) Microalgae for oil: strain selection, induction of lipid synthesis and outdoor mass cultivation in a low-cost photobioreactor. Biotechnol Bioeng 102:100–112 source

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    Remaining biomass from oil extraction can be used for biomethane, bioethanol, biosorbents for wastewater treatment, and biofertilizer.

    “The remaining biomass from oil extraction can be used for biomethane, bioethanol, biosorbents for wastewater treatment, and biofertilizer [11, 16–18].”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [11] Mata TM, Martins AA, Caetano NS (2010) Microalgae for biodiesel production and other applications: a review. Renew Sust Energ Rev 14:217–232 source

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    • cites [16] Maurya R, Ghosh T, Paliwal C, Shrivastav A, Chokshi K, Pancha I, Ghosh A, Mishra S (2014) Biosorption of methylene blue by de-oiled algal biomass: equilibrium, kinetics and artificial neural network modelling. PLoS One 9:e109545 source

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    • cites [17] Rashid N, Rehman MSU, Han J-I (2013) Recycling and reuse of spent microalgal biomass for sustainable biofuels. Biochem Eng J 75:101–107 source

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    • cites [18] Scott SA, Davey MP, Dennis JS, Horst I, Howe CJ, Lea-Smith DJ, Smith AG (2010) Biodiesel from algae: challenges and prospects. Curr Opin Biotechnol 21:277–286 source

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    Premisecitation

    Microalgae are versatile, used for energy, biofuels, nutrition, health, cosmetics, and wastewater treatment, fixing nitrogen, carbon, and heavy metals.

    “Microalgae are versatile, used for energy, biofuels, nutrition, health, cosmetics, and wastewater treatment, fixing nitrogen, carbon, and heavy metals [8].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [8] Mutum L, Janda T, Ördög V, Molnár Z (2022) Biologia Futura: potential of different forms of microalgae for soil improvement. Biol Futur 73(1):1–8. https://doi.org/10.1007/s42977-021-00103-2 source

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    Reliance on fossil fuels worsens climate change and drives the search for alternative energy sources.

    “This reliance on fossil fuels worsens climate change and drives the search for alternative energy sources [2].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [2] Bhattacharya S, Maurya R, Mishra SK, Ghosh T, Patidar SK, Paliwal C, Chokshi K, Pancha I, Maiti S, Mishra S (2016) Solar driven mass cultivation and the extraction of lipids from Chlorella variabilis: a case study. Algal Res 14:137–142 source

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    The use of fossil fuels for energy, driven by the industrial revolution, has led to climate change and energy insecurity.

    “The use of fossil fuels for energy, driven by the industrial revolution, has led to climate change and energy insecurity [1].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Kothari R, Ahmad S, Pathak VV, Pandey A, Kumar A, Shankarayan R, Black PN, Tyagi VV (2021) Algal-based biofuel generation through flue gas and wastewater utilization: a sustainable prospective approach. Biomass Convers Biorefinery 11:1419–1442. https://doi.org/10.1007/s13399-019-00533-y source

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    Microalgae have higher growth rates and yields than conventional plants.

    “Microalgae have been studied extensively as a viable alternative feedstock for biofuels [10], with higher growth rates and yields than conventional plants [11].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [11] Mata TM, Martins AA, Caetano NS (2010) Microalgae for biodiesel production and other applications: a review. Renew Sust Energ Rev 14:217–232 source

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    Microalgae have over 200,000 species and are the largest primary producers on Earth.

    “With over 200,000 species, they are the largest primary producers on Earth [4].”
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    • cites [4] Purohit P, Chaturvedi V (2018) Biomass pellets for power generation in India: a techno-economic evaluation. Environ Sci Pollut Res 25:29614–29632. https://doi.org/10.1007/s11356-018-2960-8 source

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    Algal biomass contains lipids, proteins, and carbohydrates, varying by species and cultivation.

    “Algal biomass contains lipids, proteins, and carbohydrates, varying by species and cultivation [13].”
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    • cites [13] Maurya R, Chokshi K, Ghosh T, Trivedi K, Pancha I, Kubavat D, Mishra S, Ghosh A (2016) Lipid extracted microalgal biomass residue as a fertilizer substitute for Zea mays L. Front Plant Sci 6. https://doi.org/10.3389/fpls.2015.01266 source

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    Research and development efforts must focus on addressing gaps in current knowledge and innovation to overcome existing challenges.

    “Research and development efforts must focus on addressing gaps in current knowledge and innovation to overcome existing challenges [31].”
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    • cites [31] Wang Q, Lu Y, Xin Y, Wei L, Huang S, Xu J (2016) Genome editing of model oleaginous microalgae Nannochloropsis spp. by CRISPR/Cas9. Plant J 88:1071–1081. https://doi.org/10.1111/tpj.13307 source

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    Typically, methanol or ethanol is used as the alcohol source in the transesterification reaction.

    “Typically, methanol or ethanol is used as the alcohol source in the transesterification reaction [42].”
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    • cites [42] Tan XB, Lam MK, Uemura Y, Lim JW, Wong CY, Lee KT (2018) Cultivation of microalgae for biodiesel production: a review on upstream and downstream processing. Chin J Chem Eng 26:17–30 source

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    Achieving market acceptance and consumer adoption requires overcoming perceptions of performance, safety, and compatibility with existing infrastructure.

    “Achieving market acceptance and consumer adoption requires overcoming perceptions of performance, safety, and compatibility with existing infrastructure [30].”
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    • cites [30] Stephens E, Ross IL, Mussgnug JH, Wagner LD, Borowitzka MA, Posten C, Kruse O, Hankamer B (2010) Future prospects of microalgal biofuel production systems. Trends Plant Sci 15:554–564. https://doi.org/10.1016/j.tplants.2010.06.003 source

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    Premisecitation

    Lipid-extracted algal biomass can be used for hydrogen and methane generation, fermentable sugar production, bioethanol development, biofertilizer creation, and animal feed production.

    “Lipid-extracted algal biomass can be used for hydrogen and methane generation, fermentable sugar production, bioethanol development, biofertilizer creation, and animal feed production [19].”
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    • cites [19] Tran D-T, Lee HR, Jung S, Park MS, Yang J-W (2018) Lipid-extracted algal biomass based biocomposites fabrication with poly (vinyl alcohol). Algal Res 31:525–533 source

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    Inexpensive alcohols like methanol and ethanol are suitable for synthesizing biodiesel due to their affordability and favorable properties.

    “Inexpensive alcohols like methanol and ethanol are suitable for synthesizing biodiesel due to their affordability and favorable properties [41].”
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    • cites [41] Karpagam R, Jawaharraj K, Gnanam R (2021) Review on integrated biofuel production from microalgal biomass through the outset of transesterification route: a cascade approach for sustainable bioenergy. Sci Total Environ 766:144236. https://doi.org/10.1016/j.scitotenv.2020.144236 source

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    Regulatory and policy barriers must be navigated to meet compliance with environmental standards and land use policies.

    “Regulatory and policy barriers must be navigated to meet compliance with environmental standards and land use policies [28].”
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    • cites [28] Lardon L, Hélias A, Sialve B, Steyer JP, Bernard O (2009) Life-cycle assessment of biodiesel production from microalgae. Environ Sci Technol 43:6475–6481. https://doi.org/10.1021/es900705j source

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    Addressing environmental concerns, such as impacts on water quality and biodiversity, is crucial for sustainable production practices.

    “Addressing environmental concerns, such as impacts on water quality and biodiversity, is crucial for sustainable production practices [29].”
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    • cites [29] Halim R, Danquah MK, Webley PA (2012) Extraction of oil from microalgae for biodiesel production: a review. Biotechnol Adv 30:709–732. https://doi.org/10.1016/j.biotechadv.2012.01.001 source

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    Microalgal lipid extraction has low costs but downsides like poor mass transfer, limited yield, and long extraction times.

    “While microalgal lipid extraction has low costs, it also has downsides like poor mass transfer, limited yield, and long extraction times [34].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [34] Kim J, Yoo G, Lee H, Lim J, Kim K, Kim CW, Park MS, Yang J-W (2013) Methods of downstream processing for the production of biodiesel from microalgae. Biotechnol Adv 31:862–876. https://doi.org/10.1016/j.biotechadv.2013.04.006 source

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    Long-term sustainability considerations, including land use competition and lifecycle environmental impacts, necessitate strategic planning and mitigation measures.

    “Long-term sustainability considerations, including land use competition and lifecycle environmental impacts, necessitate strategic planning and mitigation measures [32].”
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    • cites [32] Zaimes GG, Khanna V (2013) Microalgal biomass production pathways: evaluation of life cycle environmental impacts. Biotechnol Biofuels 6:88. https://doi.org/10.1186/1754-6834-6-88 source

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    Using wastewater nutrients for microalgae cultivation can reduce production costs and advance the industry.

    “To address this, it is important to explore using wastewater nutrients for microalgae cultivation, which can reduce production costs and advance the industry [49].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [49] Nagi M, He M, Li D, Gebreluel T, Cheng B, Wang C (2020) Utilization of tannery wastewater for biofuel production: new insights on microalgae growth and biomass production. Sci Rep 10:1530. https://doi.org/10.1038/s41598-019-57120-4 source

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    Premisecitation

    Ensuring economic viability entails developing cost-effective cultivation and processing methods, as well as strategies for generating revenue from by-products.

    “Ensuring economic viability entails developing cost-effective cultivation and processing methods, as well as strategies for generating revenue from by-products [27].”
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    • cites [27] Chisti Y (2008) Biodiesel from microalgae beats bioethanol. Trends Biotechnol 26:126–131. https://doi.org/10.1016/j.tibtech.2007.12.002 source

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    Premisecitation

    In Chlorella variabilis, nitrogen deprivation and long-chain alkenes/genome scale metabolic model targeting conversion of C16 to C18 fatty acid enhanced production of desirable fatty acids.

    “| 4 | Chlorella variabilis | 46.16 | Nitrogen deprivation and long-chain alkenes/Genome scale metabolic model | Converting C16 to C18 fatty acid | Genetic sequencing, lipid profiling | Endogenous promoters or heterologous expression constructs | Enhanced production of desirable fatty acids | Biofuel feedstock optimization | [92] |”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [92] Sorigué D, Légeret B, Cuiné S, Morales P, Mirabella B, Guédeney G, Li-Beisson Y, Jetter R, Peltier G, Beisson F (2016) Microalgae synthesize hydrocarbons from long-chain fatty acids via a light-dependent pathway. Plant Physiol 171:2393–2405. https://doi.org/10.1104/pp.16.00462 source

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    Biomethane production using agricultural waste is economically and environmentally sustainable, reducing competition for resources.

    “Others highlighted the economic and environmental sustainability of biomethane production using agricultural waste, reducing competition for resources [73].”
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    • cites [73] Housagul S, Sirisukpoka U, Boonyawanich S, Pisutpaisal N (2014) Biomethane production from co-digestion of banana peel and waste glycerol. Energy Procedia 61:2219–2223 source

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    The residual biomass resulting from the transesterification process serves as a by-product and can be repurposed for animal feed, containing glycerol, carbohydrates, and proteins.

    “Moreover, the residual biomass resulting from the transesterification process serves as a by-product and can be repurposed for animal feed, containing glycerol, carbohydrates, and proteins [67].”
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    • cites [67] Zahan KA, Kano M (2018) Biodiesel production from palm oil, its by-products, and mill effluent: A review. Energies 11:2132 source

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    Premisecitation

    Using pure and raw algal biomass can produce high-value products like biodiesel, bioethanol, biohydrogen, and biogas, as well as cosmetics, medicines, feed, and fertilizers.

    “Using pure and raw algal biomass can produce high-value products like biodiesel, bioethanol, biohydrogen, and biogas, as well as cosmetics, medicines, feed, and fertilizers [1].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Kothari R, Ahmad S, Pathak VV, Pandey A, Kumar A, Shankarayan R, Black PN, Tyagi VV (2021) Algal-based biofuel generation through flue gas and wastewater utilization: a sustainable prospective approach. Biomass Convers Biorefinery 11:1419–1442. https://doi.org/10.1007/s13399-019-00533-y source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Genetically modified microalgae exhibit heightened productivity, environmental tolerance, and resistance to insects.

    “For example, genetically modified microalgae exhibit heightened productivity, environmental tolerance, and resistance to insects [22].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] Shokravi H, Shokravi Z, Heidarrezaei M, Ong HC, Rahimian Koloor SS, Petrů M, Lau WJ, Ismail AF (2021) Fourth generation biofuel from genetically modified algal biomass: challenges and future directions. Chemosphere 285:131535. https://doi.org/10.1016/j.chemosphere.2021.131535 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    DMB composed of starch and cellulose can be easily hydrolyzed to yield monosaccharides, which are then fermented to produce ethanol.

    “DMB composed of starch and cellulose can be easily hydrolyzed to yield monosaccharides, which are then fermented to produce ethanol [80, 82, 83].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [80] Shokrkar H, Ebrahimi S, Zamani M (2018) Enzymatic hydrolysis of microalgal cellulose for bioethanol production, modeling and sensitivity analysis. Fuel 228:30–38 source

      Not checked in the free run.

    • cites [82] Laurens L, Nagle N, Davis R, Sweeney N, Van Wychen S, Lowell A, Pienkos P (2015) Acid-catalyzed algal biomass pretreatment for integrated lipid and carbohydrate-based biofuels production. Green Chem 17:1145–1158 source

      Not checked in the free run.

    • cites [83] Shokrkar H, Ebrahimi S, Zamani M (2017) Bioethanol production from acidic and enzymatic hydrolysates of mixed microalgae culture. Fuel 200:380–386 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    De-oiled microalgal biomass (DMB) has potential for creating value-added bioproducts and environmental benefits.

    “It is crucial to not only focus on algal-based biofuel technologies, as de-oiled microalgal biomass (DMB) has potential for creating value-added bioproducts and environmental benefits [1].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Kothari R, Ahmad S, Pathak VV, Pandey A, Kumar A, Shankarayan R, Black PN, Tyagi VV (2021) Algal-based biofuel generation through flue gas and wastewater utilization: a sustainable prospective approach. Biomass Convers Biorefinery 11:1419–1442. https://doi.org/10.1007/s13399-019-00533-y source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In Auxenochlorella protothecoides, genome scale and core metabolic model targeting biodiesel enhanced lipid productivity and increased lipid content.

    “| 1 | Auxenochlorella protothecoides | 22.92 | Genome scale and core metabolic model | Biodiesel | Sequencing, phenotypic characterization, lipid analysis | Endogenous promoters or heterologous expression constructs | Enhanced lipid productivity, increased lipid content | Biofuel production | [89] |”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [89] Gao C, Wang Y, Shen Y, Yan D, He X, Dai J, Wu Q (2014) Oil accumulation mechanisms of the oleaginous microalga Chlorella protothecoides revealed through its genome, transcriptomes, and proteomes. BMC Genomics 15:582. https://doi.org/10.1186/1471-2164-15-582 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Biomethane production from food waste and sewage sludge has higher energy efficiency and lower greenhouse gas emissions, making it an effective waste management strategy.

    “A study revealed higher energy efficiency and lower greenhouse gas emissions in biomethane production from food waste and sewage sludge, making it an effective waste management strategy [72].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [72] Cheng J, Ding L, Lin R, Yue L, Liu J, Zhou J, Cen K (2016) Fermentative biohydrogen and biomethane co-production from mixture of food waste and sewage sludge: effects of physiochemical properties and mix ratios on fermentation performance. Appl Energy 184:1–8 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationnone given

    A range of primary and by-products derived from algae are commercially viable, supporting a green economy.

    “A range of primary and by-products derived from algae are commercially viable, supporting a green economy (Table 1).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A range of lipid content has been observed in Chlamydomonas reinhardtii strain D1.

    “and a range of lipid content has been observed in Chlamydomonas reinhardtii strain D1 [60].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [60] Yu KL, Lau BF, Show PL, Ong HC, Ling TC, Chen W-H, Ng EP, Chang J-S (2017) Recent developments on algal biochar production and characterization. Bioresour Technol 246:2–11 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Food waste and sewage sludge had higher energy efficiency and lower greenhouse gas emissions than grass and agricultural waste for biohydrogen production.

    “They found that food waste and sewage sludge had higher energy efficiency and lower greenhouse gas emissions than grass and agricultural waste [75].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [75] Li M, Zhao Y, Guo Q, Qian X, Niu D (2008) Bio-hydrogen production from food waste and sewage sludge in the presence of aged refuse excavated from refuse landfill. Renew Energy 33:2573–2579 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Challenges in biomethane production include ammonia production from high N content, which can be mitigated through co-digestion and pre-treatment methods like enzyme-pre-treated DMB.

    “Challenges in biomethane production include ammonia production from high N content, which can be mitigated through co-digestion and pre-treatment methods like enzyme-pre-treated DMB [71].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [71] Kasinath A, Fudala-Ksiazek S, Szopinska M, Bylinski H, Artichowicz W, Remiszewska-Skwarek A, Luczkiewicz A (2021) Biomass in biogas production: pretreatment and codigestion. Renew Sust Energ Rev 150:111509 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Microalgae-based bioethanol reduces greenhouse gas emissions and water usage compared to traditional methods, enhancing economic and environmental sustainability and mitigating competition with food production.

    “Microalgae-based bioethanol also reduces greenhouse gas emissions and water usage compared to traditional methods, enhancing economic and environmental sustainability and mitigating competition with food production [80–82].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [80] Shokrkar H, Ebrahimi S, Zamani M (2018) Enzymatic hydrolysis of microalgal cellulose for bioethanol production, modeling and sensitivity analysis. Fuel 228:30–38 source

      Not checked in the free run.

    • cites [81] Chng LM, Lee KT, Chan DJC (2017) Synergistic effect of pretreatment and fermentation process on carbohydrate-rich Scenedesmus dimorphus for bioethanol production. Energy Convers Manag 141:410–419 source

      Not checked in the free run.

    • cites [82] Laurens L, Nagle N, Davis R, Sweeney N, Van Wychen S, Lowell A, Pienkos P (2015) Acid-catalyzed algal biomass pretreatment for integrated lipid and carbohydrate-based biofuels production. Green Chem 17:1145–1158 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Microalgae directly transform atmospheric CO2 into organic algal biomass, making them valuable sources of organic matter.

    “These microalgae directly transform atmospheric CO2 into organic algal biomass, making them valuable sources of organic matter [105].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [105] Guo S, Wang P, Wang X, Zou M, Liu C, Hao J (2020) Microalgae as biofertilizer in modern agriculture. Microalgae biotechnology for food, health and high value products, pp 397–411 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Nannochloropsis sp. is a potential source of essential fatty acid (EPA).

    “Nannochloropsis sp. is also a potential source of essential fatty acid (EPA) [100].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [100] Mitra M, Patidar SK, George B, Shah F, Mishra S (2015) A euryhaline Nannochloropsis gaditana with potential for nutraceutical (EPA) and biodiesel production. Algal Res 8:161–167 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In 24 microalgae strains, cis-zeatin is the most common cytokinin.

    “Concentrations of auxins and cytokinins were analyzed in 24 microalgae strains with cis-zeatin as the most common cytokinin [124].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [124] Stirk W, Bálint P, Tarkowská D, Novák O, Strnad M, Ördög V, Van Staden J (2013) Hormone profiles in microalgae: gibberellins and brassinosteroids. Plant Physiol Biochem 70:348–353 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Cyanobacteria can fix atmospheric nitrogen, reducing the need for nitrogen fertilizers in crops.

    “Cyanobacteria can fix atmospheric nitrogen, reducing the need for nitrogen fertilizers in crops [106, 107].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [106] Bhattacharjee R, Dey UK (2014) Biofertilizer, a way towards organic agriculture: a review. Afr J Microbiol Res 8:2332–2343 source

      Not checked in the free run.

    • cites [107] Chittora D, Meena M, Barupal T, Swapnil P, Sharma K (2020) Cyanobacteria as a source of biofertilizers for sustainable agriculture. Biochem Biophys Rep 22:100737. https://doi.org/10.1016/j.bbrep.2020.100737 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    An aqueous cell extract of Acutodesmus dimorphus increases seed germination rate, plant growth, and floral parts in Solanum lycopersicum L.

    “An aqueous cell extract of Acutodesmus dimorphus was utilized as a biofertilizer on Solanum lycopersicum L. plants. The results indicated an increase in seed germination rate, plant growth, and floral parts [117].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [117] Garcia-Gonzalez J, Sommerfeld M (2016) Biofertilizer and biostimulant properties of the microalga Acutodesmus dimorphus. J Appl Phycol 28:1051–1061. https://doi.org/10.1007/s10811-015-0625-2 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Chlorella kessleri extract improves germination, seedling growth, leaf surface area, pigment concentration, and sodium and potassium accumulation in roots and shoots of Vicia faba.

    “Another extract from Chlorella kessleri was applied to Vicia faba plants, showing a significant effect on improved germination, seedling growth, leaf surface area, pigment concentration, and sodium and potassium accumulation in roots and shoots [122].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [122] El-Naggar AH, Osman MEHE-S, Gheda SF (2005) Influence of the aqueous extracts of Ulva lactuca and Chlorella kessleri on growth and yield of Vicia faba. Algological Studies/Archiv f \ u r Hydrobiologie, Supplement Volumes, vol 116. pp 213–229. https://doi.org/10.1127/1864-1318/2005/0116-0213 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Spirulina platensis and Chlorella vulgaris enhance soil nutrients and promote crop development.

    “Microalgae like Spirulina platensis and Chlorella vulgaris enhance soil nutrients and promote crop development [103].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [103] Alobwede E, Leake JR, Pandhal J (2019) Circular economy fertilization: testing micro and macro algal species as soil improvers and nutrient sources for crop production in greenhouse and field conditions. Geoderma 334:113–123. https://doi.org/10.1016/j.geoderma.2018.07.049 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    DMB shows great promise in various applications, offering an alternative protein source, improved growth, and reduced reliance on traditional feed ingredients.

    “Despite this, DMB shows great promise in various applications, offering an alternative protein source, improved growth, and reduced reliance on traditional feed ingredients [102].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [102] Nagappan S, Das P, AbdulQuadir M, Thaher M, Khan S, Mahata C, Al-Jabri H, Vatland AK, Kumar G (2021) Potential of microalgae as a sustainable feed ingredient for aquaculture. J Biotechnol 341:1–20 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Improvement in nutrient uptake efficiency enhances tolerance to abiotic stresses, resulting in enhanced crop quality.

    “Consequently, this improvement in nutrient uptake efficiency enhances tolerance to abiotic stresses, resulting in enhanced crop quality [116].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [116] Drobek M, Frąc M, Cybulska J (2019) Plant biostimulants: importance of the quality and yield of horticultural crops and the improvement of plant tolerance to abiotic stress—a review. Agronomy 9:335 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    MBS do not function as MBF and do not directly provide nutrients to plants.

    “In this context, MBS do not function as MBF and do not directly provide nutrients to the plants.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [116] Drobek M, Frąc M, Cybulska J (2019) Plant biostimulants: importance of the quality and yield of horticultural crops and the improvement of plant tolerance to abiotic stress—a review. Agronomy 9:335 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Microalgae biomass improves germination, N uptake, and biomass accumulation in crops.

    “Microalgae biomass improves germination, N uptake, and biomass accumulation in crops [108].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [108] Nayak M, Swain DK, Sen R (2019) Strategic valorization of de-oiled microalgal biomass waste as biofertilizer for sustainable and improved agriculture of rice (Oryza sativa L.) crop. Sci Total Environ 682:475–484 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Sugarcane as a feedstock can diminish the global warming impact associated with biodiesel production.

    “In the investigation of microalgae cultivation, Orfield et al. [138] propose sugarcane as a feedstock, demonstrating its potential to diminish the global warming impact associated with biodiesel production.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [138] Orfield ND, Levine RB, Keoleian GA, Miller SA, Savage PE (2015) Growing algae for biodiesel on direct sunlight or sugars: a comparative life cycle assessment. ACS Sustain Chem Eng 3:386–395. https://doi.org/10.1021/sc5004117 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    Integrating processes in microalgae biorefineries using circular bioeconomy strategies boosts efficiency, profitability, and resource recovery.

    “Integrating processes in microalgae biorefineries using circular bioeconomy strategies boosts efficiency, profitability, and resource recovery.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Oil productivity attained through open ponds and PBR cultivation methods incurs costs ranging from $8.52 to $18.10 per gallon and $9.84 to $20.53 per gallon for biodiesel, respectively.

    “Specifically, the oil productivity attained through open ponds and PBR cultivation methods incurs costs ranging from $8.52 to $18.10 per gallon and $9.84 to $20.53 per gallon for biodiesel, respectively [134].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [134] Davis R, Aden A, Pienkos PT (2011) Techno-economic analysis of autotrophic microalgae for fuel production. Appl Energy 88:3524–3531. https://doi.org/10.1016/j.apenergy.2011.04.018 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    Microalgae have great potential for supporting long-term circular bioeconomy systems.

    “Microalgae have great potential for supporting long-term circular bioeconomy systems.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Incorporating an algal unit in a sugarcane biorefinery can save costs and reduce CO2 emissions by co-producing algal biofuel and biochar for enhanced sustainability.

    “Incorporating an algal unit in a sugarcane biorefinery can save costs and reduce CO2 emissions by co-producing algal biofuel and biochar for enhanced sustainability [142].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [142] De Bhowmick G, Sarmah AK, Sen R (2019) Zero-waste algal biorefinery for bioenergy and biochar: a green leap towards achieving energy and environmental sustainability. Sci Total Environ 650:2467–2482 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Scenedesmus and Chlorella strains demonstrate clearance rates of 48% and 31%, respectively, for 20 mg Cr/L.

    “Similarly, Scenedesmus and Chlorella strains demonstrated clearance rates of 48% and 31%, respectively, for 20 mg Cr/L [110, 126].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [110] Ammar EE, Aioub AA, Elesawy AE, Karkour AM, Mouhamed MS, Amer AA, El-Shershaby NA (2022) Algae as bio-fertilizers: between current situation and future prospective. Saudi J Biol Sci 29:3083–3096 source

      Not checked in the free run.

    • cites [126] Dhaliwal SS, Singh J, Taneja PK, Mandal A (2020) Remediation techniques for removal of heavy metals from the soil contaminated through different sources: a review. Environ Sci Pollut Res 27:1319–1333 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Protein hydrolysates, active components of plant biostimulants, enhance biological activity in crop growth and development.

    “Protein hydrolysates, active components of plant biostimulants, enhance biological activity in crop growth and development [125].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [125] Stirk WA, Ördög V, Novák O, Rolčík J, Strnad M, Bálint P, van Staden J (2013) Auxin and cytokinin relationships in 24 microalgal strains1. J Phycol 49:459–467 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Production of oil from microalgae is not competitive compared to other plant sources and fossil fuels due to heightened electricity consumption.

    “However, a separate LCA study, conducted by Jez et al. [139], underscores that the production of oil from microalgae is not competitive when compared to other plant sources and fossil fuels due to heightened electricity consumption.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [139] Jez S, Spinelli D, Fierro A, Dibenedetto A, Aresta M, Busi E, Basosi R (2017) Comparative life cycle assessment study on environmental impact of oil production from micro-algae and terrestrial oilseed crops. Bioresour Technol 239:266–275. https://doi.org/10.1016/j.biortech.2017.05.027 source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given

    Microalgae can capture CO2 and absorb nutrients from various waste forms like solids, liquids, and gases.

    “They can capture CO2 and absorb nutrients from various waste forms like solids, liquids, and gases.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Co-cultivating different microalgae species can enhance lipid content, thereby mitigating production costs.

    “However, the prospect of co-cultivating different microalgae species emerges as a potential strategy to enhance lipid content, thereby mitigating production costs [135].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [135] Judd SJ, Al Momani FAO, Znad H, Al Ketife AMD (2017) The cost benefit of algal technology for combined CO2 mitigation and nutrient abatement. Renew Sust Energ Rev 71:379–387. https://doi.org/10.1016/j.rser.2016.12.068 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Microalgal biorefineries offer biofuel recovery and other product production.

    “Microalgal biorefineries offer biofuel recovery and other product production [3].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] Banu JR, Kavitha S, Gunasekaran M, Kumar G (2020) Microalgae based biorefinery promoting circular bioeconomy-techno economic and life-cycle analysis. Bioresour Technol 302:122822 source

      Not checked in the free run.

61 of 61

  • The paper relies on this without support.

    Fossil fuels are non-renewable due to limited supply and rapid depletion from excessive consumption.

    “However, fossil fuels are non-renewable due to their limited supply and rapid depletion from excessive consumption.”

  • The paper relies on this without support.

    Utilization of GM strains in fully lined open raceway ponds may incur costs up to 25% higher than unlined counterparts.

    “The utilization of GM strains in fully lined open raceway ponds may incur costs up to 25% higher than their unlined counterparts.”

  • The paper relies on this without support.

    Implementation of a plastic hoop air-supported greenhouse for pond cultivation is estimated at $60,000 per hectare.

    “The implementation of a plastic hoop air-supported greenhouse for pond cultivation is estimated at $60,000 per hectare.”

  • The paper relies on this without support.

    The Soxhlet extraction method is generally considered the most effective, achieving 100% recovery of all lipids in microalgae.

    “The Soxhlet extraction method is generally considered the most effective, achieving 100% recovery of all lipids in microalgae.”

  • The paper relies on this without support.

    The methanol-chloroform mixture can extract both neutral and polar lipids, unlike hexane.

    “Unlike hexane, which selectively dissolves non-polar lipids, the methanol-chloroform mixture can extract both neutral and polar lipids.”

  • The paper relies on this without support.

    Transesterification is commonly used to lower the viscosity of microalgae oil by turning it into fatty acid methyl esters (FAME) or biodiesel.

    “Transesterification is commonly used to lower the viscosity of microalgae oil by turning it into fatty acid methyl esters (FAME) or biodiesel.”

  • The paper relies on this without support.

    The efficiency of transesterification and purification procedures is mainly based on the number of the biodiesel’s measurable characteristics, including water content, flash point, methanol concentration, and glyceride content.

    “The efficiency of the transesterification and purification procedures are mainly based on the number of the biodiesel’s measurable characteristics, which includes its water content, flash point, methanol concentration, and glyceride content.”

  • The paper relies on this without support.

    A catalyst is needed to facilitate the reaction between the parent oil (triglyceride) and the short-chain alcohol to produce FAME and glycerol.

    “A catalyst is needed to facilitate the reaction between the parent oil (triglyceride) and the short-chain alcohol to produce FAME and glycerol.”

  • The paper relies on this without support.

    Catalysts like acids, bases, or enzymes can enhance the reaction rate and product yield.

    “Catalysts like acids (hydrochloric, sulfuric, phosphoric, sulfonic), bases (sodium hydroxide, potassium hydroxide), or enzymes (lipase) can enhance the reaction rate and product yield.”

  • The paper relies on this without support.

    Heterogeneous catalysts like magnesium oxide, barium oxide, calcium oxide, and strontium oxide have successfully catalyzed transesterification reactions, being non-corrosive, environmentally friendly, and cost-effective.

    “Heterogeneous catalysts like magnesium oxide, barium oxide, calcium oxide, and strontium oxide have successfully catalyzed transesterification reactions, being non-corrosive, environmentally friendly, and cost-effective.”

  • The paper relies on this without support.

    Heterogeneous acid catalysts are unaffected by water and free fatty acids during transesterification.

    “Heterogeneous acid catalysts are also studied, unaffected by water and free fatty acids during transesterification.”

  • The paper relies on this without support.

    Lipid extraction from algal biomass is mainly used for biodiesel, but bioplastics can also be derived from lipids, proteins, and carbohydrates.

    “Lipid extraction from algal biomass is mainly used for biodiesel, but bioplastics can also be derived from lipids, proteins, and carbohydrates.”

  • The paper relies on this without support.

    Aqueous hydrolysate residues and cell debris from biofuel conversion can be used to make proteins, glucose, peptides, and amino acids.

    “Aqueous hydrolysate residues and cell debris from biofuel conversion can be used to make proteins, glucose, peptides, and amino acids.”

  • The paper relies on this without support.

    DMB can be used to make proteins for food and feed, bioplastics, foams, glue, and biocomposites.

    “DMB can then be used to make proteins for food and feed, bioplastics, foams, glue, and biocomposites.”

  • The paper relies on this without support.

    De-lipidified microalgae residue with a high C/N ratio aids in producing methane-rich biogas.

    “De-lipidified microalgae residue with a high C/N ratio aids in producing methane-rich biogas.”

  • The paper relies on this without support.

    Algae have great potential for biohydrogen production due to their fast growth, high biomass, and adaptability, and they reduce greenhouse gases and water usage compared to traditional methods.

    “Algae have great potential for biohydrogen production due to their fast growth, high biomass, and adaptability. They also reduce greenhouse gases and water usage compared to traditional methods.”

  • The paper relies on this without support.

    Biohydrogen production is still costly and limited by feedstock availability and conversion efficiency.

    “A study on cost and scalability showed that it is still costly and limited by feedstock availability and conversion efficiency.”

  • The paper relies on this without support.

    Pre-treating dried microalgae biomass is crucial for releasing cellular carbon, enabling microbes to produce hydrogen or methane.

    “Studies show that pre-treating dried microalgae biomass is crucial for releasing cellular carbon, enabling microbes to produce hydrogen or methane.”

  • The paper relies on this without support.

    De-oiled microalgal biomass is a by-product of microalgal biodiesel production, known for high protein content and essential nutrients.

    “De-oiled microalgal biomass is a by-product of microalgal biodiesel production, known for its high protein content and essential nutrients.”

  • The paper relies on this without support.

    DMB can replace fishmeal as a protein source for chickens, improving their growth and egg production.

    “A recent study found that it can replace fishmeal as a protein source for chickens, improving their growth and egg production.”

  • The paper relies on this without support.

    Using DMB in fish feed enhances growth performance and feed efficiency, reducing costs and environmental impacts.

    “Similarly, using it in fish feed enhances growth performance and feed efficiency, reducing costs and environmental impacts.”

  • The paper relies on this without support.

    The intricate composition of microalgal cell walls presents a challenge in digestion, complicating utilization of microalgal biomass as feed for prawns.

    “The intricate composition of microalgal cell walls presents a challenge in the digestion process, thereby complicating the utilization of this biomass as a feed source for prawns.”

  • The paper relies on this without support.

    Economic feasibility of using microalgal biomass for prawn feed is impeded by significant production costs.

    “Furthermore, the economic feasibility of such pursuits is impeded by significant production costs.”

  • The paper relies on this without support.

    Microalgae biomass is rich in micro- and macronutrients, especially nitrogen (N), phosphorus (P), and potassium (K), making it suitable as an organic slow-release fertilizer.

    “Microalgae biomass is rich in micro- and macronutrients, especially nitrogen (N), phosphorus (P), and potassium (K), making it suitable as an organic slow-release fertilizer.”

  • The paper relies on this without support.

    Arthrospira sp. contains nitrogen, phosphorus, and potassium concentrations of 6.70%, 2.47%, and 1.14%, respectively.

    “For example, Arthrospira sp. contains nitrogen, phosphorus, and potassium concentrations of 6.70%, 2.47%, and 1.14%, respectively.”

  • The paper relies on this without support.

    Arthrospira sp. biomass is lead-free, indicating its safety as a plant growth stimulant.

    “Importantly, Arthrospira sp. biomass is lead-free, indicating its safety as a plant growth stimulant.”

  • The paper relies on this without support.

    The microalgal species, metal ions, and growth system conditions (pH) influence metal absorption mechanisms.

    “The microalgal species, metal ions (such as Lead (Pb), Nickel (Ni), Cadmium (Cd), and Zinc (Zn)), and growth system conditions (pH) influence metal absorption mechanisms.”

  • The paper relies on this without support.

    Microalgae contain significant concentrations of brassinosteroids and gibberellins.

    “Microalgae also contain significant concentrations of brassinosteroids and gibberellins.”

  • The paper relies on this without support.

    Amino acids present in microalgae benefit plant growth and agricultural productivity, and mitigate abiotic damage.

    “Amino acids present in microalgae are well-known biostimulants that benefit plant growth and agricultural productivity, as well as mitigating abiotic damage.”

  • The paper relies on this without support.

    Microalgae are not typically recommended for consumption as they tend to absorb harmful metals.

    “Microalgae are not typically recommended for consumption as they tend to absorb harmful metals.”

  • The paper relies on this without support.

    Microalgae have exceptional ability to remove metals from water and other contaminants, making them valuable for bioremediation.

    “However, their exceptional ability to remove metals from water and other contaminants makes them valuable for bioremediation purposes.”

  • The paper relies on this without support.

    Scenedesmus is commonly used for heavy metal removal in bioremediation studies.

    “Scenedesmus is commonly used for heavy metal removal in bioremediation studies.”

  • The paper relies on this without support.

    Factors such as pH, temperature, contact time, and initial concentration influence the effectiveness of biosorption.

    “Factors such as pH, temperature, contact time, and initial concentration influenced the effectiveness of biosorption.”

  • The paper relies on this without support.

    Current large-scale processes relying on single or dual product systems are not economically feasible.

    “However, current large-scale processes relying on single or dual product systems are not economically feasible.”

  • The paper relies on this without support.

    Biodiesel from microalgae oil can reduce CO2 emissions by 78%.

    “Biodiesel from microalgae oil can reduce CO2 emissions by 78%.”

  • The paper relies on this without support.

    Biomethane from residual biomass can power biodiesel facilities.

    “Biomethane from residual biomass can power biodiesel facilities.”

  • The paper relies on this without support.

    Producing 10,000 tonnes of microalgae containing 30% lipids has an estimated cost of $2.80 per liter, rendering it more expensive than conventional fuels.

    “The economic implications become apparent when considering the production of 10,000 tonnes of microalgae containing 30% lipids, with an estimated cost of $2.80 per liter, rendering it more expensive than conventional fuels.”

  • The paper relies on this without support.

    Microalgae can capture CO2 and nutrients efficiently.

    “Microalgae can capture CO2 and nutrients efficiently.”
38 of 38

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Table 2 attributes an Auxenochlorella biogas result to a Scenedesmus biofuel study

    Minor

    The table cites reference [64] for biogas production from Auxenochlorella protothecoides, but the listed title of [64] identifies a study of biodiesel and bioethanol production from Scenedesmus bijugatus.

  • Soxhlet lipid-recovery claim conflicts with the stated solvent limitation

    Minor

    The paper describes Soxhlet extraction as using hexane and claims it recovers all microalgal lipids. It also says hexane selectively dissolves non-polar lipids, while another solvent mixture extracts both neutral and polar lipids; hexane-based extraction therefore cannot recover all lipids as claimed.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. Mahapatra DM, Chanakya H, Joshi N, Ramachandra T, Murthy G (2018) Algae-based biofertilizers: a biorefinery approach. Microorganisms for Green. Revolution: Volume 2: Microbes for Sustainable Agro-ecosystem, pp 177–196
  2. Aly M, Esawy MA (2008) Evaluation of Spirulina platensis as bio stimulator for organic farming systems. J Genet Eng Biotechnol 6:1–7

Cited by

Sorted by citations

Related

Authors
Ezhumalai, G., Arun, M., Manavalan, A., Rajkumar, R., & Heese, K.
Affiliations
  • Bharathiar University (IN)
  • Saveetha University (IN)
  • Hanyang University (KR)
Corresponding author
  • Rajkumar, Renganathan
  • Heese, Klaus
ORCID
Venue
Microbial Ecology
Publisher
Springer Science and Business Media LLC
Published
2024-04-25
Volume
87
Issue
1
Pages
61-61
ISSN
  • 0095-3628 (ISSN-L)
  • 1432-184X
DOI
10.1007/s00248-024-02376-1
PMC
PMC11045622
OpenAlex
W4395456586
Cited by
99
References
140
Citations by year
2026: 51 · 2025: 42 · 2024: 6
FWCI
2.06
Type
journal article
Language
en
Open access
Licence
Locations
  • Microbial Ecology (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • Saveetha Dental College
  • National Research Foundation
  • National Research Foundation of Korea
  • Council for Higher Education
  • Tamil Nadu State Council for Higher Education (27.04.2021)
Topics
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Algal biology and biofuel production
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Microbial Metabolic Engineering and Bioproduction
  • Life Sciences › Agricultural and Biological Sciences › General Agricultural and Biological Sciences › Bioeconomy and Sustainability Development
Keywords
microalgae, microalgal biofuels, circular bioeconomy, microalgal biomass, lipid extraction, microalgae biorefinery, value-added products, biofertilizers, feed supplements, biosorption, heavy metal removal, dye removal, industrial-scale production, greenhouse gas emissions
MeSH terms
Cyanobacteria, Carbon Dioxide, Seaweed, Biomass, Biofuels, Microalgae

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

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