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15 pages, 1837 KiB

Open AccessArticle

Glucose Conversion for Biobutanol Production from Fresh Chlorella sorokiniana via Direct Enzymatic Hydrolysis

by Jinzhi Yang, Di Cai, Xudong Liu, Liqi Zhu, Changwei Zhang, Qing Peng, Yanxia Han, Guozhen Liu and Ming Yang

Fermentation 2023, 9(3), 284; https://doi.org/10.3390/fermentation9030284 - 14 Mar 2023

Cited by 2 | Viewed by 2080

Abstract

Microalgae, which accumulate considerable carbohydrates, are a potential source of glucose for biofuel fermentation. In this study, we investigated the enzymatic hydrolysis efficiency of wet microalgal biomass compared with freeze-dried and oven-dried biomasses, both with and without an acidic pretreatment. With the dilute [...] Read more.

Microalgae, which accumulate considerable carbohydrates, are a potential source of glucose for biofuel fermentation. In this study, we investigated the enzymatic hydrolysis efficiency of wet microalgal biomass compared with freeze-dried and oven-dried biomasses, both with and without an acidic pretreatment. With the dilute sulfuric acid pretreatment followed by amy (α-amylase and amyloglucosidase) and cellulase hydrolysis, approximately 95.4% of the glucose was recovered; however, 88.5% was released by the pretreatment with 2% (w/v) sulfuric acid, which indicates the potential of the acids for direct saccharification process. There were no considerable differences in the glucose yields among the three kinds of materials. In the direct amy hydrolysis without any pretreatment, a 78.7% glucose yield was obtained, and the addition of cellulase had no significant effect on the hydrolysis to glucose. Compared with the oven-dried biomass, the wet biomass produced a substantially higher glucose yield, which is possibly because the cross-linked cells of the oven-dried biomass prevented the accessibility of the enzymes. According to the results, the fresh microalgal biomass without cell disruption can be directly used for enzymatic hydrolysis to produce glucose. The enzymatic hydrolysate of the wet microalgal biomass was successfully used for acetone–butanol–ethanol (ABE) fermentation, which produced 7.2 g/L of ABE, indicating the application potential of wet microalgae in the bioalcohol fuel fermentation process. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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12 pages, 1836 KiB

Open AccessArticle

Lipid Recovery from Microalgae Biomass Using Sugaring-Out Extraction in Liquid Biphasic Flotation System

by Nurul Syahirah Mat Aron, Kit Wayne Chew, Zengling Ma, Yang Tao, Malinee Sriariyanun, Inn Shi Tan, Cường Nguyễn Mạnh, Ao Xia, Tonni Agustiono Kurniawan and Pau Loke Show

Fermentation 2023, 9(3), 198; https://doi.org/10.3390/fermentation9030198 - 21 Feb 2023

Cited by 1 | Viewed by 1614

Abstract

The increase in global temperature calls for ambitious action to reduce the release of greenhouse gases into the atmosphere. The transportation sector contributes up to 25% of the total emissions released, mainly from the burning of vehicle fuel. Therefore, scientists from all around [...] Read more.

The increase in global temperature calls for ambitious action to reduce the release of greenhouse gases into the atmosphere. The transportation sector contributes up to 25% of the total emissions released, mainly from the burning of vehicle fuel. Therefore, scientists from all around the world are focusing on finding a sustainable alternative to conventional vehicle fuel. Biofuel has attracted much attention, as it shows great potential for the replacement of traditional fossil fuels. However, the main bottlenecks of biofuel are the ongoing controversial conflict between food security with biofuel production. Therefore, this study focuses on a sustainable extraction of lipids from microalgae for the production of biofuel using a liquid biphasic flotation system coupled with sugaring-out method. This is the first study to combine the methods of liquid biphasic flotation system with the sugaring-out technique. It represents a holistic study of optimum and effective conditions needed to extract lipids from the system and to understand the reliability of sugar solution as the agent of cell disruption. At the 15-min flotation time, 150 g/L of fructose solution with a 1:2 mass separating agent-acetonitrile ratio successfully extracted up to 74% of lipid from Chlorella sorokiniana CY-1. Two types of fatty acid methyl esters were recovered from the study, with C5:0 being the main component extracted. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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12 pages, 2155 KiB

Open AccessArticle

Synergistic Effect of Surfactant on Disperser Energy and Liquefaction Potential of Macroalgae (Ulva intestinalis) for Biofuel Production

by Rinsha Puthiya Veettil, Rabia, Dinesh Kumar Mathew, Rashmi Gondi, Kavitha Sankarapandian, Meganathan Kannan, Gopalakrishnan Kumar, Siham Y. Al-Qaradawi and Rajesh Banu Jeyakumar

Fermentation 2023, 9(1), 55; https://doi.org/10.3390/fermentation9010055 - 09 Jan 2023

Cited by 2 | Viewed by 1732

Abstract

The objective of this study was to evaluate the effect of surfactant on disperser homogenization pretreatment for macroalgae (Ulva intestinalis) to enhance biogas production. The macroalgae are subjected to surfactant coupled disperser pretreatment, which enhanced the liquefaction and improved the biomethane [...] Read more.

The objective of this study was to evaluate the effect of surfactant on disperser homogenization pretreatment for macroalgae (Ulva intestinalis) to enhance biogas production. The macroalgae are subjected to surfactant coupled disperser pretreatment, which enhanced the liquefaction and improved the biomethane production. The outcome of this study revealed that 10,000 rpm at 20 min with a specific energy input of 1748.352 kJ/ kg total solids (TS) are the optimum conditions for surfactant disperser pretreatment (SDP), which resulted in the liquefaction rate of 20.08% with soluble organics release of 1215 mg/L and showed a better result than disperser pretreatment (DP) with a liquefaction rate of 14%. Biomethane production through the SDP method was found to be 0.2 g chemical oxygen demand (COD)/g COD, which was higher than DP (0.11 g COD/g COD). SDP was identified to be a synergetic pretreatment method with an energy ratio and net profit of about 0.91 and 104.04 United States dollars (USD)/ton, respectively. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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13 pages, 3193 KiB

Open AccessArticle

Neural-Network-Inspired Correlation (N2IC) Model for Estimating Biodiesel Conversion in Algal Biodiesel Units

by Abdullah Bin Mahfouz, Abulhassan Ali, Mark Crocker, Anas Ahmed, Rizwan Nasir and Pau Loke Show

Fermentation 2023, 9(1), 47; https://doi.org/10.3390/fermentation9010047 - 06 Jan 2023

Cited by 5 | Viewed by 1346

Abstract

Algal biodiesel is of growing interest in reducing carbon emissions to the atmosphere. The production of biodiesel is affected by many process parameters. Although many research works have been conducted, the influence of each parameter on biodiesel production is not well understood when [...] Read more.

Algal biodiesel is of growing interest in reducing carbon emissions to the atmosphere. The production of biodiesel is affected by many process parameters. Although many research works have been conducted, the influence of each parameter on biodiesel production is not well understood when considering a complete system. Therefore, the experimental data from literature sources related to types of algae, methanol-to-algal-oil ratio, temperature, and time on the biodiesel production rate were reviewed and introduced into a neural-network-inspired correlation (N2IC) model to study the rate of transesterification. The developed N2IC model optimized for biodiesel production is based on the studied variables, specifically reaction time, temperature, methanol-to-algal-oil ratio, and type of algae. It was found from ANN analysis that the reaction time is the most significant parameter with 87% importance, followed by temperature (85%), alcohol-to-oil-molar ratio (75%), and type of algae (62%). Using error analysis, the results from the proposed N2IC model show excellent agreement with the experimentally obtained values with an overall 5% error. The results show that the N2IC model can be utilized effectively to solve the problem of industrial biodiesel production when various operating data are readily available. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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17 pages, 4955 KiB

Open AccessArticle

Algal Biomass Accumulation in Waste Digestate after Anaerobic Digestion of Wheat Straw

by Lyudmila Kabaivanova, Juliana Ivanova, Elena Chorukova, Veneren Hubenov, Lilyana Nacheva and Ivan Simeonov

Fermentation 2022, 8(12), 715; https://doi.org/10.3390/fermentation8120715 - 07 Dec 2022

Cited by 1 | Viewed by 1227

Abstract

Cultivation of microalgae in waste digestate is a promising cost-effective and environmentally friendly strategy for algal biomass accumulation and valuable product production. Two different digestates obtained as by-products of the anaerobic fermentation at 35 °C and 55 °C of wheat straw as a [...] Read more.

Cultivation of microalgae in waste digestate is a promising cost-effective and environmentally friendly strategy for algal biomass accumulation and valuable product production. Two different digestates obtained as by-products of the anaerobic fermentation at 35 °C and 55 °C of wheat straw as a renewable source for biogas production in laboratory-scale bioreactors were tested as cultivation media for microalgae after pretreatment with active carbon for clarification. The strains of microalgae involved were the red marine microalga Porphyridium cruentum, which reached 4.7 mg/mL dry matter when grown in thermophilic digestate and green freshwater microalga-Scenedesmus acutus, whose growth was the highest—7.3 mg/mL in the mesophilic digestate. During cultivation, algae reduced the available nutrient components in the liquid digestate at the expense of increasing their biomass. This biomass can find further applications in cosmetics, pharmacy, and feed. The nitrogen and phosphorus uptake from both digestates during algae cultivation was monitored and modeled. The results led to the idea of nonlinear dynamic approximations with an exponential character. The purpose was to develop relatively simple nonlinear dynamic models based on available experimental data, as knowing the mechanisms of the considered processes can permit creating protocols for industrial-scale algal production toward obtaining economically valuable products from microalgae grown in organic waste digestate. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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18 pages, 1521 KiB

Open AccessArticle

Resource Recovery of the Wastewater-Derived Nutrients into Algal Biomass Followed by Its Cascading Processing to Multiple Products in a Circular Bioeconomy Paradigm

by Muhammad Nabeel Haider, Chen-Guang Liu, Tanveer A. Tabish, Deepanraj Balakrishnan, Pau-Loke Show, Shaza Yehya Abdulhamed Qattan, Munazza Gull and Muhammad Aamer Mehmood

Fermentation 2022, 8(11), 650; https://doi.org/10.3390/fermentation8110650 - 17 Nov 2022

Cited by 5 | Viewed by 1599

Abstract

The cultivation of Plectonema terebrans BERC10 in wastewater and integrating the wastewater-derived biomass followed by its processing for multiple products in a biorefinery could help in achieving environmental sustainability and cost effectiveness. This study evaluated the resource recovery potential of the cyanobacterium Plectonema [...] Read more.

The cultivation of Plectonema terebrans BERC10 in wastewater and integrating the wastewater-derived biomass followed by its processing for multiple products in a biorefinery could help in achieving environmental sustainability and cost effectiveness. This study evaluated the resource recovery potential of the cyanobacterium Plectonema terebrans BERC10 from urban wastewater followed by the cascading processing of the biomass into multiple bioproducts. The annual biomass productivity ranged from 0.035–0.064 gL⁻¹d⁻¹ and contained 40–46% lipids and 20–38% protein. The cascading processing of the biomass resulted in multiple products, including 53 mgg⁻¹ of high-value pigments and high-quality biodiesel in accordance with American and European standards. The pigment-free and de-fatted residual biomass was used as a sole feedstock (30–70 gL⁻¹) to produce enzymes and mycoproteins via fungal fermentation employing Aspergillus niger and Aspergillus oryzae. Interestingly, A. oryzae produced 28 UmL⁻¹ of α-amylase and the final residues were mycoproteins after 96 h. Furthermore, the strain removed 80–90% of total phosphorous, 90–99% of total nitrogen, and significantly lowered the COD, BOD, and TDS of urban wastewater. The data demonstrated that P. terebrans has substantial potential for resource recovery and could become a candidate for a wastewater-derived algal biorefinery. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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16 pages, 1829 KiB

Open AccessArticle

Strategy Development for Microalgae Spirulina platensis Biomass Cultivation in a Bubble Photobioreactor to Promote High Carbohydrate Content

by Rohit Saxena, Rosa M. Rodríguez-Jasso, Mónica L. Chávez-Gonzalez, Cristóbal N. Aguilar, Guillermo Quijano and Héctor A. Ruiz

Fermentation 2022, 8(8), 374; https://doi.org/10.3390/fermentation8080374 - 07 Aug 2022

Cited by 6 | Viewed by 5532

Abstract

As a counter to climate change, energy crises, and global warming, microalgal biomass has gained a lot of interest as a sustainable and environmentally favorable biofuel feedstock. Microalgal carbohydrate is considered one of the promising feedstocks for biofuel produced via the bioconversion route [...] Read more.

As a counter to climate change, energy crises, and global warming, microalgal biomass has gained a lot of interest as a sustainable and environmentally favorable biofuel feedstock. Microalgal carbohydrate is considered one of the promising feedstocks for biofuel produced via the bioconversion route under a biorefinery system. However, the present culture technique, which uses a commercial medium, has poor biomass and carbohydrate productivity, creating a bottleneck for long-term microalgal-carbohydrate-based biofuel generation. This current investigation aims toward the simultaneous increase in biomass and carbohydrate accumulation of Spirulina platensis by formulating an optimal growth condition under different concentrations of nitrogen and phosphorous in flasks and a bubble photobioreactor. For this purpose, the lack of nitrogen (NaNO₃) and phosphorous (K₂HPO₄) in the culture medium resulted in an enhanced Spirulina platensis biomass and total carbohydrate 0.93 ± 0.00 g/L and 74.44% (w/w), respectively. This research is a significant step in defining culture conditions that might be used to tune the carbohydrate content of Spirulina. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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Review

Jump to: Research

47 pages, 946 KiB

Open AccessReview

From Microalgae to Bioenergy: Recent Advances in Biochemical Conversion Processes

by Sheetal Kishor Parakh, Zinong Tian, Jonathan Zhi En Wong and Yen Wah Tong

Fermentation 2023, 9(6), 529; https://doi.org/10.3390/fermentation9060529 - 29 May 2023

Cited by 2 | Viewed by 2649

Abstract

Concerns about rising energy demand, fossil fuel depletion, and global warming have increased interest in developing and utilizing alternate renewable energy sources. Among the available renewable resources, microalgae biomass, a third-generation feedstock, is promising for energy production due to its rich biochemical composition, [...] Read more.

Concerns about rising energy demand, fossil fuel depletion, and global warming have increased interest in developing and utilizing alternate renewable energy sources. Among the available renewable resources, microalgae biomass, a third-generation feedstock, is promising for energy production due to its rich biochemical composition, metabolic elasticity, and ability to produce numerous bioenergy products, including biomethane, biohydrogen, and bioethanol. However, the true potential of microalgae biomass in the future bioenergy economy is yet to be realized. This review provides a comprehensive overview of various biochemical conversion processes (anaerobic digestion, direct biophotolysis, indirect biophotolysis, photo fermentation, dark fermentation, microalgae-catalyzed photo fermentation, microalgae-catalyzed dark fermentation, and traditional alcoholic fermentation by ethanologenic microorganisms) that could be adapted to transform microalgae biomass into different bioenergy products. Recent advances in biochemical conversion processes are compiled and critically analyzed, and their limitations in terms of process viability, efficacy, scalability, and economic and environmental sustainability are highlighted. Based on the current research stage and technological development, biomethane production from anaerobic digestion and bioethanol production from traditional fermentation are identified as promising methods for the future commercialization of microalgae-based bioenergy. However, significant challenges to these technologies’ commercialization remain, including the high microalgae production costs and low energy recovery efficiency. Future research should focus on reducing microalgae production costs, developing an integrated biorefinery approach, and effectively utilizing artificial intelligence tools for process optimization and scale-up to solve the current challenges and accelerate the development of microalgae-based bioenergy. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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34 pages, 4893 KiB

Open AccessReview

Microalgal Feedstock for Biofuel Production: Recent Advances, Challenges, and Future Perspective

by Shoyeb Khan, Probir Das, Mohammed Abdul Quadir, Mahmoud Ibrahim Thaher, Chandan Mahata, Sami Sayadi and Hareb Al-Jabri

Fermentation 2023, 9(3), 281; https://doi.org/10.3390/fermentation9030281 - 13 Mar 2023

Cited by 10 | Viewed by 11136

Abstract

Globally, nations are trying to address environmental issues such as global warming and climate change, along with the burden of declining fossil fuel reserves. Furthermore, countries aim to reach zero carbon emissions within the existing and rising global energy crisis. Therefore, bio-based alternative [...] Read more.

Globally, nations are trying to address environmental issues such as global warming and climate change, along with the burden of declining fossil fuel reserves. Furthermore, countries aim to reach zero carbon emissions within the existing and rising global energy crisis. Therefore, bio-based alternative sustainable feedstocks are being explored for producing bioenergy. One such renewable energy resource is microalgae; these are photosynthetic microorganisms that grow on non-arable land, in extreme climatic conditions, and have the ability to thrive even in sea and wastewater. Microalgae have high photosynthetic efficiencies and biomass productivity compared to other terrestrial plants. Whole microalgae biomass or their extracted metabolites can be converted to various biofuels such as bioethanol, biodiesel, biocrude oil, pyrolytic bio-oil, biomethane, biohydrogen, and bio jet fuel. However, several challenges still exist before faster and broader commercial application of microalgae as a sustainable bioenergy feedstock for biofuel production. Selection of appropriate microalgal strains, development of biomass pre-concentrating techniques, and utilization of wet microalgal biomass for biofuel production, coupled with an integrated biorefinery approach for producing value-added products, could improve the environmental sustainability and economic viability of microalgal biofuel. This article will review the current status of research on microalgal biofuels and their future perspective. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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21 pages, 1109 KiB

Open AccessReview

Advancements in Microalgal Biorefinery Technologies and Their Economic Analysis and Positioning in Energy Resource Market

by Ishita Chanana, Parneet Kaur, Lokender Kumar, Pradeep Kumar and Sourabh Kulshreshtha

Fermentation 2023, 9(3), 202; https://doi.org/10.3390/fermentation9030202 - 21 Feb 2023

Cited by 8 | Viewed by 2623

Abstract

In the energy sector, bioenergy has been utilized as a replacement for non-renewable resources. Due to the depletion of resources, mankind may face adversities in the future. To overcome these challenges, sustainable and reliable bioenergy-based alternatives are to be used. Bioenergy sources are [...] Read more.

In the energy sector, bioenergy has been utilized as a replacement for non-renewable resources. Due to the depletion of resources, mankind may face adversities in the future. To overcome these challenges, sustainable and reliable bioenergy-based alternatives are to be used. Bioenergy sources are bio-based alternatives that have become acceptable in society for their renewability, sustainability, and environmentally friendly characteristics, but they still lag in the energy market due to their less cost-effective output of upstream and downstream processing in comparison with age-old fossil fuels. This review provides a detailed overview of their techno-economic and life cycle assessment, their positioning and competition in the energy market, and the strategies that might assist them in overcoming the market challenges. Microalgal bioenergy products have been lifting their market positioning at a slower rate that is almost unnoticeable, but their assistance in becoming a better solution against adversities of energy resource depletion in the future makes them quite promising. The new research alternatives for microalgal biomass conversion in biorefinery products for bioenergy production, which are based on combating pollution and reuse of waste products, along with the strategic application for combating the energy market competition, have also been highlighted. Full article

(This article belongs to the Special Issue Algae—the Medium of Bioenergy Conversion)

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