Algal Biorefineries and the Circular Bioeconomy

Algal Products and Processes

Sanjeet Mehariya, Obulisamy Parthiba Karthikeyan, Shashi Kant Bhatia, Sanjeet Mehariya, Obulisamy Parthiba Karthikeyan, Shashi Kant Bhatia

• Publisher: CRC Press
• Year: 2022
• ISBN:
  9781000557473
• Edition: 1
• Topic: Scienze biologiche
• Subtopic: Biotecnologia

"Algae are mysterious and fascinating organisms that hold great potential for discovery and biotechnology."

—Dr. Thierry Tonon, Department of Biology, University of York

"Science is a beautiful gift to humanity; we should not distort it."

—A.P.J. Abdul Kalam

In this book, we emphasize the importance of algal biotechnology as a sustainable platform to replace the conventional fossil-based economy. With this focus, Volume 2 summarizes the up-to-date literature and knowledge and discusses the advances in algal cultivation, genetic improvement, wastewater treatment, resource recovery, commercial operation, and technoeconomic analysis of algal biotechnology.

FEATURES

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• Discusses in detail recent developments in algae cultivation and biomass harvesting

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• Provides an overview of genetic engineering and algal-bacteria consortia to improve productivity

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• Presents applications of algae in the area of wastewater treatment and resource recovery

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• Provides case studies and technoeconomic analysis to understand the algal biorefinery

Shashi Kant Bhatia, PhD, is an Associate Professor in the Department of Biological Engineering, Konkuk University, Seoul, South Korea.

Sanjeet Mehariya, PhD, is a Postdoctoral Researcher at the Department of Chemistry, Umeå University, Umeå, Sweden.

Obulisamy Parthiba Karthikeyan, PhD, is a Research Scientist and Lecturer (Adjunct) in the Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA.

1 Marine Macroalgal Biorefinery Recent Developments and Future Perspectives

Nitin Trivedi and Dhanashree Mone

DBT-ICT Centre for Energy Biosciences, Institute of Chemical Technology, Matunga, Mumbai, India

Arijit Sankar Mondal and Ritu Sharma

Department of Microbiology, Guru Nanak Institute of Pharmaceutical Science and Technology (Life Science), Kolkata, India

DOI: 10.1201/9781003188094-1

CONTENTS

1. 1.1 Introduction
2. 1.2 Green Macroalgae
3. 1.2.1 Advanced Green Macroalgae Cultivation Strategies to Uplift the Biorefinery System
4. 1.2.2 Essential Components in Green Macroalgae Important for Sequential Biorefinery Processes
5. 1.2.3 Green Macroalgae Biorefinery Protocol with the Advanced Extraction Process
6. 1.2.4 Potential Primary Products Obtained during the Biorefinery Process
7. 1.2.5 Potential Secondary Products Obtained during the Biorefinery Process
8. 1.2.5.1 Bioethanol
9. 1.2.5.2 Biohydrogen
10. 1.2.5.3 Biogas
11. 1.2.5.4 Biodiesel
12. 1.2.5.5 Other Miscellaneous Applications
13. 1.3 Red Macroalgae
14. 1.3.1 Cultivation of Red Macroalgae for a Biorefinery Approach
15. 1.3.2 Bioactive Components of Red Macroalgae for a Biorefinery Approach
16. 1.3.3 Primary Products Obtained during the Biorefinery Process
17. 1.3.4 Secondary Products Obtained during the Biorefinery Process
18. 1.3.4.1 Bioethanol
19. 1.3.4.2 Biodiesel
20. 1.3.4.3 Biohydrogen and Biogas
21. 1.3.4.4 Other Miscellaneous Products
22. 1.4 Brown Macroalgae
23. 1.4.1 Cultivation of Brown Macroalgae for a Biorefinery Approach
24. 1.4.2 Bioactive Components of Brown Macroalgae for a Biorefinery Approach
25. 1.4.3 Primary Products Obtained during Biorefinery Process
26. 1.4.4 Secondary Products Obtained during the Biorefinery Process
27. 1.4.4.1 Biogas
28. 1.4.4.2 Bioethanol
29. 1.4.4.3 Biohydrogen and Biomethane
30. 1.4.4.4 Other Miscellaneous Applications
31. 1.5 Future Perspectives
32. 1.6 Conclusion
33. Acknowledgments
34. References

1.1 Introduction

Marine macroalgae are one of the precious gems of the marine ecosystem. Based on the morphology and pigmentation, macroalgae have been classified into three types: red (Rhodophyceae), green (Chlorophyceae), and brown (Phaeophyceae). Macroalgae are a valuable bioresource with several added advantages over terrestrial crops, such as (a) no fertile land and freshwater requirement, (b) no pesticide and fertilizer requirement, (c) no competition with food, feed, and industrial crops, (d) speedy biomass production in several macroalgal species such as Ulva meridionalis (Tsubaki et al., 2020) and Saccharina latissima (Venolia et al., 2020), and (e) CO₂ sequestration and in-turn production of O₂ by the process of photosynthesis (Kraan, 2013).

Macroalgae are abundant sources of bioactive components, namely polysaccharides, minerals, fatty acids, vitamins, pigments, etc., which are useful in various industrial applications (cosmeceutical, pharmaceutical, food, feed, paint, fertilizer, and energy source). In addition, macroalgae are effective against numerous health conditions, such as diabetes, obesity, hypertension, inflammation, and viral infections (Ganesan et al., 2019; Kılınç et al., 2013). Although the global macroalgae production is massive, approximately, 32386.2 thousand tons wet weight (in 2018) (FAO (Food and Agricultural Organization), 2018), still there is a need for the efficient utilization of the biomass to fulfill the rising demands of macroalgae-based bioproducts. Earlier macroalgae were used to extract single components for specific applications, e.g., only carrageenan extraction from red macroalgae (Naseri et al., 2019). However, in the past decade, researchers across the globe have designed strategies to extract multiple value-added products in a sequential biorefinery process.

Biorefinery can be defined as the sustainable utilization of biomass for producing a wide range of biological products viz. food, feed, and chemicals as well as biofuel. The benefit of biorefinery includes the reduction in the energy and chemical requirements during the product extraction process, cost-effectiveness, and environmental friendliness, along with the production of multiple products within a cascading manner. Efficient utilization and production of the spectrum of products result in minimal waste generation and effortless effluent management (Mehariya et al., 2021a, 2021b, 2021c).

Over the past decades, increasing demand for macroalgae products has resulted in growing macroalgae waste and residual biomass; for example, before processing, feedstock gets rejected when quality standards are not met, or after processing, residual generation leads to the wastage of feedstock. To effectively utilize the macroalgae biomass, the residue from the first process could be taken into account as an input for another process. In this cascading approach, biomass is first used for producing value-added primary products, followed by secondary products. The optimization of the process for the re-utilization of the biomass yields multiple valuable products, such as pharmaceuticals and nutraceuticals, besides focusing on the traditional applications, such as phycocolloids. Further investigating the process for the effective utilization of the biomass can lead to zero waste generation (Torres et al., 2019b; Balina et al., 2017). Figure 1.1 illustrates the schematic flowchart of a complete sequential macroalgae biorefinery workflow.

Figure 1.1 The schematic flowchart of a possible sequential macroalgal biorefinery. CO₂, carbon dioxide; O₂, oxygen; MRLE, mineral-rich liquid extract; FAME analysis, fatty acid methyl ester analysis; GC-MS, gas chromatography-mass spectrometry; GC-FID, gas chromatography-flame ionization detector; MAE, microwave-assisted extraction; UAE, ultrasound-assisted extraction; EAE, enzyme-assisted extraction; SFE, supercritical fluid extraction; FT-IR, Fourier-transform infrared spectroscopy; SPs, sulfated polysaccharides; LC-MS, liquid chromatography-mass spectrometry; HPLC, high-performance liquid chromatography; PXRD, powder X-ray diffraction.

The circular bioeconomy focuses on economic development by minimizing resource consumption along with the reduction of waste generation. This process uses the circular approach of reuse, remanufacture, and recycle rather than the linear approach of make-use-waste. The biorefinery concept uplifts the circular economy resulting in the valorization of macroalgae biomass by drawing multiple value-added products from the same biomass and reducing waste generation (Ubando et al., 2020). Figure 1.2 demonstrates the possible model for circular bioeconomy through macroalgae biorefinery.

Figure 1.2 Macroalgal biorefinery as an important source for circular bioeconomy.

In the last decade, tremendous progress has been made in the area of macroalgal growth engineering for higher and quality biomass production, followed by process optimization for sequential extraction of multiple value-added products via biorefinery approach. However, demonstration of biorefinery process is still in progress. Biorefinery studies of green, red, and brown macroalgae, including different extraction methods and products obtained, are shown in Table 1.1.

Table 1.1 Examples of Extraction Methods/Processes for Obtaining Several Biorefinery Products from Different Macroalgae

Macroalgae	Extraction method/Process	Biorefinery products obtained	References
Green Macroalgae
Ulva rigida	Pulse electric field (PEF), microwave, and ultrasound treatments; acid and hydrothermal hydrolysis extraction; pyrolysis; anaerobic digestion; saccharification; and fermentation	Protein, ash (salt) removal, polysaccharides (ulvan, cellulose, etc.), feedstock, biofuel (bioethanol), and other bioenergy products	(Zollmann et al., 2019)
Ulva ohnoi	Aqueous, thermal, and chemical (acid/alkaline) treatment	Salt, pigment, ulvan, and protein	(Glasson et al., 2017)
Ulva fasciata	Mechanical treatment (grinding), aqueous and solvent extraction treatment, enzymatic hydrolysis, and fermentation	Mineral-rich liquid extract (MRLE) as liquid fertilizer, cellulose, ulvan, lipid, feedstock, and biofuel (bioethanol)	(Trivedi et al., 2016)
Ulva lactuca	Mechanical and heat treatment, solvent, alkali, and chemical extraction	MRLE, lipid, ulvan, protein, and cellulose	(Gajaria et al., 2017)
Ulva lactuca	Pretreatment, enzymatic hydrolysis, and fermentation	Biofuel (acetone, butanol, and ethanol)	(van der Wal et al., 2013)
Ulva lactuca	Aqueous, thermal, and chemical (acid/alkaline) treatment and anaerobic digestion	Sap, ulvan, protein, and biogas	(Mhatre et al., 2019)
Ulva lactuca	Mechanical, aqueous, and chemical treatment, hydrothermal, thermochemical (acid) and enzymatic hydrolysis, saccharification, and fermentation	Proteins, lipids, ulvan, cellulose, pigments, dietary food, feedstocks, and biofuel (biodiesel, bio-oil, bioethanol, acetone, and biogas	(Dominguez and Loret 2019)
Red Macroalgae
Eucheuma cottonii	Enzymatic hydrolysis, saccharification, and fermentation	Κ-carrageenan and biofuel (bioethanol)	(Tan and Lee 2014)
Gracilaria gracilis	Chemical (acid) treatment and pyrolysis	Polysaccharides, phycobilipr...