•Potential of microalgae biorefinery for producing high value products is assessed.•Conventional processes of microalgae biorefinery are discussed.•Recent technologies on microalgae biorefinery are ...reviewed.•Techno-economic analysis and LCA assessment on microalgal biorefinery are addressed.•Advantages of microalgae biorefinery and derived high-value products are emphasized.
Microalgae have received much interest as a biofuel feedstock in response to the uprising energy crisis, climate change and depletion of natural sources. Development of microalgal biofuels from microalgae does not satisfy the economic feasibility of overwhelming capital investments and operations. Hence, high-value co-products have been produced through the extraction of a fraction of algae to improve the economics of a microalgae biorefinery. Examples of these high-value products are pigments, proteins, lipids, carbohydrates, vitamins and anti-oxidants, with applications in cosmetics, nutritional and pharmaceuticals industries. To promote the sustainability of this process, an innovative microalgae biorefinery structure is implemented through the production of multiple products in the form of high value products and biofuel. This review presents the current challenges in the extraction of high value products from microalgae and its integration in the biorefinery. The economic potential assessment of microalgae biorefinery was evaluated to highlight the feasibility of the process.
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•Persistent organic pollutants beget adverse effects on environment and ecosystem.•Conventional organic wastewater treatment is highly complex and expensive.•Microalgae-bacteria ...synergy shows several advantages to the economy and environment.•Microalgae-bacteria consortia is a latent wastewater treatment to remove POPs.•Mechanisms involved mainly via biosorption, bioaccumulation and biodegradation.
The litter of persistent organic pollutants (POPs) into the water streams and soil bodies via industrial effluents led to several adverse effects on the environment, health, and ecosystem. For the past decades, scientists have been paying efforts in the innovation and development of POPs removal from wastewater treatment. However, the conventional methods used for the removal of POPs from wastewater are costly and could lead to secondary pollution including soil and water bodies pollution. In recent, the utilization of green mechanisms such as biosorption, bioaccumulation and biodegradation has drawn attention and prelude the potential of green technology globally. Microalgae-bacteria consortia have emerged to be one of the latent wastewater treatment systems. The synergistic interactions between microalgae and bacteria could proficiently enhance the existing biological wastewater treatment system. This paper will critically review the comparison of conventional and recent advanced wastewater treatment systems and the mechanisms of the microalgae-bacteria symbiosis system.
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•Simple and rapid biphasic partitioning for phycobiliprotein purification.•Incorporation of bubbles assistance for purification improvements.•Optimization of process parameters for ...liquid biphasic flotation.•C-phycocyanin recovery of 90.4% with purification fold of 3.49.
Liquid biphasic flotation (LBF), an integrated process of liquid biphasic system (LBS) and adsorptive bubbles flotation, was used for the purification of C-phycocyanin from S. platensis microalgae. Various experimental parameters such as type of phase forming polymer and salt, concentration of phase forming components, system pH, volume ratio, air flotation time and crude extract concentration were evaluated to maximise the C-phycocyanin recovery yield and purity. The optimal conditions for the LBF system achieving C-phycocyanin purification fold of 3.49 compared to 2.43 from the initial LBF conditions was in polyethylene glycol (PEG) 4000 and potassium phosphate combination, with 250 g/L of polymer and salt concentration each, volume ratio of 1:0.85, system pH of 7.0, air flotation duration of 7 min and phycocyanin crude extract concentration of 0.625 %w/w. The LBF has effectively enhanced the purification of C-phycocyanin in a cost effective and simple processing.
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•An alternative and rapid approach for the recovery of astaxanthin from H. pluvialis.•Implementation of bubble-assisted technologies for the recovery of astaxanthin.•Optimization of ...various parameters for liquid biphasic flotation system.•Astaxanthin recovery of 78.38 ± 0.93 with extraction efficiency of 99.86 ± 0.05%
This work aimed to study the application of liquid biphasic flotation (LBF) for the efficient and rapid recovery of astaxanthin from H. pluvialis microalgae. The performance of LBF for the extraction of astaxanthin was studied comprehensively under different operating conditions, including types and concentrations of food-grade alcohol and salt, volume ratio, addition of neutral salt, flotation period, and mass of dried H. pluvialis biomass powder. The maximum recovery, extraction efficiency and partition coefficient of astaxanthin obtained from the optimum LBF system were 95.11 ± 1.35%, 99.84 ± 0.05% and 385.16 ± 3.87, respectively. A scaled-up LBF system was also performed, demonstrating the feasibility of extracting natural astaxanthin from microalgae at a larger scale. This exploration of LBF system opens a promising avenue to the extraction of astaxanthin at lower cost and shorter processing time.
Summary
Biofuel has emerged as an alternative source of energy to reduce the emissions of greenhouse gases in the atmosphere and combat global warming. Biofuels are classified into first, second, ...third and fourth generations. Each of the biofuel generations aims to meet the global energy demand while minimizing environmental impacts. Sustainability is defined as meeting the needs of the current generations without jeopardizing the needs of future generations. The aim of sustainability is to ensure continuous growth of the economy while protecting the environment and societal needs. Thus, this paper aims to evaluate the sustainability of these four generations of biofuels. The objectives are to compare the production of biofuel, the net greenhouse gases emissions, and energy efficiency. This study is important in providing information for the policymakers and researchers in the decision‐making for the future development of green energy. Each of the biofuel generations shows different benefits and drawbacks. From this study, we conclude that the first generation biofuel has the highest biofuel production and energy efficiency, but is less effective in meeting the goal of reducing the greenhouse gases emission. The third generation biofuel shows the lowest net greenhouse gases emissions, allowing the reduction of greenhouse gases in the atmosphere. However, the energy required for the processing of the third generation biofuel is higher and, this makes it less environmentally friendly as fossil fuels are used to generate electricity. The third and fourth generation feedstocks are the potential sustainable source for the future production of biofuel. However, more studies need to be done to find an alternative low cost for biofuel production while increasing energy efficiency.
• First generation biofuel has the highest biofuel yield and energy efficiency. However, the production of the biofuel opposed many sustainable development goals.
• Third and fourth generation biofuels show potential as a sustainable future green energy.
• Methods of lipid extraction of microalgae biofuel and environmental consequences of the fourth generation biofuel should be further explored.
Given their advantages of high photosynthetic efficiency and non-competition with land-based crops, algae, that are carbon-hungry and sunlight-driven microbial factories, are a promising solution to ...resolve energy crisis, food security, and pollution problems. The ability to recycle nutrient and CO2 fixation from waste sources makes algae a valuable feedstock for biofuels, food and feeds, biochemicals, and biomaterials. Innovative technologies such as the bicarbonate-based integrated carbon capture and algae production system (BICCAPS), integrated algal bioenergy carbon capture and storage (BECCS), as well as ocean macroalgal afforestation (OMA), can be used to realize a low-carbon algal bioeconomy. We review how algae can be applied in the framework of integrated low-carbon circular bioeconomy models, focusing on sustainable biofuels, low-carbon feedstocks, carbon capture, and advances in algal biotechnology.
Algae are promising players in the framework of an integrated circular bioeconomy.Wastewater and flue gas are alternative low-carbon feedstocks for algae cultivation.Bicarbonate-based integrated carbon capture and algae production system (BICCAPS), integrated algal bioenergy carbon capture and storage (BECCS), and ocean macroalgal afforestation (OMA) are algae-based carbon-capture technologies.The evolution of the biotechnology industry and government policies are promoting the growth of bioeconomies.
•Microalgae contains various nutritious and bio-active compounds.•Microalgae is capable of preventing or curing various acute and chronic diseases.•Microalgae is under-exploited crop due to its ...capital-intensive nature.•Microalgal biorefinery approach can enable sustainable growth in the market.
Microalgae has been consumed in human diet for thousands of years. It is an under-exploited crop for production of dietary foods. Microalgae cultivation does not compete with land and resources required for traditional crops and has a superior yield compared to terrestrial crops. Its high protein content has exhibited a huge potential to meet the dietary requirements of growing population. Apart from being a source of protein, presence of various bio-active components in microalgae provide an added health benefit. This review describes various microalgal sources of proteins and other bio-active components. One of the heavily studied group of bio-active components are pigments due to their anticarcenogenic, antioxidative and antihypertensive properties. Compared to various plant and floral species, microalgae contain higher amounts of pigments. Microalgal derived proteins have complete Essential Amino Acids (EAA) profiles and their protein content is higher than conventional sources such as meat, poultry and dairy products. However, microalgal based functional foods have not flooded the market. The lack of awareness coupled with scarce incentives for producers result in under-exploitation of microalgal potential. Application of microalgal derived components as dietary and nutraceutical supplements is discussed comprehensively.
The coexistence of algae and bacteria in nature dates back to the very early stages when life came into existence. The interaction between algae and bacteria plays an important role in the planet ...ecology, cycling nutrients, and feeding higher trophic levels, and have been evolving ever since. The emerging concept of algal-bacterial consortia is gaining attention, much towards environmental management and protection. Studies have shown that algal-bacterial synergy does not only promote carbon capture in wastewater bioremediation but also consequently produces biofuels from algal-bacterial biomass. This review has evaluated the optimistic prospects of algal-bacterial consortia in environmental remediation, biorefinery, carbon sequestration as well as its contribution to the production of high-value compounds. In addition, algal-bacterial consortia offer great potential in bloom control, dye removal, agricultural biofertilizers, and bioplastics production. This work also emphasizes the advancement of algal-bacterial biotechnology in environmental management through the incorporation of Industry Revolution 4.0 technologies. The challenges include its pathway to greener industry, competition with other food additive sources, societal acceptance, cost feasibility, environmental trade-off, safety and compatibility. Thus, there is a need for further in-depth research to ensure the environmental sustainability and feasibility of algal-bacterial consortia to meet numerous current and future needs of society in the long run.
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•Algal-bacterial consortia can tackle environmental issues.•Algae and bacteria are efficient in carbon capture and greenhouse gases mitigation.•Algal-bacterial technology fosters environmental sustainability in the green industry.•Industry 4.0 technologies can optimize performance and reduce ecological impacts.•In-depth research is vital to address the challenges of algal-bacterial biotechnology.
Rapidly increasing global energy consumption has caused depletion of fossil fuels, leading to the search of alternative energy resources. One of the potential solutions is utilizing algae biomass as ...the source of bioenergy. To fulfil the high biomass demands for biofuel production, it is of pivotal importance to develop feasible technologies to enable economic, efficient and high density cultivation of algae. Algae can be cultivated in either open or closed systems in the presence of nutrients and light intensity. The maximum yield, growth rate and composition of algae can be optimized according to cultivation conditions, such as temperature, pH, light intensity and nutrient concentration. The potential types of algae in contributing carbohydrate and lipids to produce biofuel such as biodiesel, bioethanol and bio-gas are reviewed. Economic feasibilities of algae based fuel production are discussed based on Life Cycle Analysis. Current challenges and future prospective are also presented to realize the use of algae as a feedstock for commercial and cost effective fuel production.
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