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Journal ArticleDOI: 10.1080/01496395.2017.1296463

Magnetic harvesting of marine algae Nannochloropsis oceanica

04 Mar 2021-Separation Science and Technology (Taylor & Francis)-Vol. 56, Iss: 4, pp 730-737
Abstract: The harvesting of Nannochloropsis oceanica was studied using magnetic separation with naked iron oxide particles. Emphasis was given to the effect of pH on harvesting efficiency, while mixing time ...

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11 results found

Journal ArticleDOI: 10.1016/J.RSER.2018.04.083
Abstract: Economically viable microalgal biodiesel production is unrealistic and unsustainable owing to expensive harvesting or dewatering techniques. Hence, immense and meticulous exploration of harvesting process is essential to identify knowledge leads by which suitable harvesting technique could be ascertained for lucrative biodiesel production. With this in view, this review aims to collate and highlight the spectrum of harvesting techniques applied to microalgae, i.e., conventional – modern, high cost- inexpensiveness, energy efficient- energy consuming process. At the outset, global energy outlook and demand had been critically addressed, and the scientific ways to tackle or satiate the fuel demand had also been highlighted in this reveiw. This review manuscript has thrown widespread light on the physical harvesting methods namely centrifugation, sedimentation, filtration, flotation and technical advantages thereof. Due to the energy-intensive and cost barrier of physical harvesting techniques, chemical methods entailing organic, inorganic, and electroflocculation have come to limelight and in this regard, microalgae used, floc recovery and the dose of flocculants have been compared and presented in detail. Further, state of the art harvesting techniques viz., bioflocculation by microalgae/bacteria, flocculation by pH adjustment, and magnetic nanocomposite based microalgal harvesting had been critically articulated. Besides discussing the several methods, this paper has summarized the key challenges in conventional and advanced harvesting techniques and also provided the scope thereof. Hence, the key suggestions and findings given in this manuscript would positively offer a well-defined roadmap in choosing foreseeable harvesting technology for cost-effective microalgal biofuel development.

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114 Citations

Journal ArticleDOI: 10.1016/J.RSER.2020.110005
Shuangxi Li1, Tianyi Hu1, Yanzhe Xu1, Jingyi Wang1  +4 moreInstitutions (1)
Abstract: The energy demands and costs of harvesting microalgal biomass make it unrealistic and unsustainable for economically feasible microalgal biofuel production Therefore, meticulous exploration of the harvesting processes is essential to identify appropriate harvesting techniques for potentially commercialized microalgal biodiesel production Flocculation may be a superior method when considering harvesting efficiency, economic cost, energy consumption and technical feasibility This review sheds some light on the recent progresses of physical/chemical flocculation and bioflocculation applied in the microalgal biomass harvesting processes Physical flocculation techniques are energy-intensive and require special equipment, creating the cost barrier for microalgal biomass harvesting Magnetic particle flocculation is much more efficient and is also recyclable In contrast, chemical flocculation that involves the application of organic and inorganic flocculants, is now in the limelight The microalgae species applied, the dosages of flocculants as well as flocculation recovery efficiencies are compared and presented in detail in this review In addition, bioflocculation as a harvesting techniques is critically described, in particular the mechanisms of autoflocculation, a promising bioflocculation by co-cultivation of microalgae with microorganisms, are explored This review also disclosed the effects of flocculant application on downstream processes, especially when chemical flocculants are applied This review intends to provide guidance for the long-term adoption of these economically beneficial mature flocculation recovery technologies in the biofuel industry Despite of considerable progress, key challenges such as further reduction of costs and the minimization of downstream product pollution risks in conventional and advanced harvesting techniques, must be addressed This article also suggests the directions for future research in microalgae harvesting and argues that the production of microalgae biofuels under potential policy intervention should be carried out in a healthy and sustainable way

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38 Citations

Journal ArticleDOI: 10.1016/J.ALGAL.2019.101683
Madonna Roy1, Kaustubha Mohanty1Institutions (1)
Abstract: Microalgae are considered as a potential and sustainable feedstock for the production of biofuels, fine chemicals, nutraceuticals, and cosmetics. This is accredited to their high lipid and carbohydrate content, fast growth and rapid CO2 sequestration ability. However, large volumes of feedstock are required to extract and process biochemicals from microalgal biomass due to the small biomass to liquid ratio. This produces substantial challenges in attaining a sustainable energy balance in microalgae-based products process operations. Additionally, the small size of microalgal cells along with their negatively charged cell surface and cell density similar to the growth medium produces challenges in microalgae harvesting. The high cost associated with microalgae harvesting is a major bottleneck for commercialization of algae-based industrial products. Hence, microalgae harvesting is recognized as an area that needs to be explored and developed. This article aims to collate and present an overview of current harvesting strategies such as physical, chemical, biological, electrical and magnetic methods along with their future prospects. This review also highlights the evolution of microalgal harvesting and elucidates the fundamental phenomena of each technology in relation to key physical parameters such as morphology, size, density and surface charge. Besides throwing widespread light on various harvesting methods, this review article has also presented their advantages and disadvantages. Life cycle assessment (LCA) and technoeconomic analysis (TEA) was reviewed to assess the feasibility of various harvesting system for commercial application based on the environmental and technoeconomic impacts. Hence, the vital proposals provided in this review article would undeniably pave the way for choosing the appropriate harvesting strategy.

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29 Citations

Open accessJournal ArticleDOI: 10.1016/J.FBP.2018.10.006
Nurafifah Fuad1, Rozita Omar1, Suryani Kamarudin1, Razif Harun1  +2 moreInstitutions (1)
Abstract: The marine species microalgae are an attractive source of feedstock for biofuel production and other bio-products such as omega-3 fatty acids and aquaculture feeds. The prevailing main nutrients in seawater environment for their growth are believed to be more economical than freshwater in terms of their cultivation system which may lead to low cost for upstream processing. Hence, marine microalgae provide attractive potential to be further explored. However, harvesting process of microalgae is known to be too costly because of their dilute nature that accounts for 20–30% of the overall production costs rendering using microalgae as the raw material not economically feasible. Currently the various harvesting methods including centrifugation, flocculation, flotation, filtration and magnetic separation had been applied to harvest marine species. For instance, harvesting by electrolytic means that require less energy to harvest marine species compared to the freshwater species. This can potentially help to reduce the challenges related to the exploitation of microalgae biomass. However, different techniques have their own advantages and drawbacks, whereas their cost and energy requirement vary accordingly depending on the selection of marine microalgal strains, equipment used and/or the choice of harvesting aid (flocculants, surfactant). Thus far, no single technique may still be proposed. Therefore, this paper aims to provide further details of each method used focusing only for marine species of microalgae with their respective advantages and disadvantages.

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18 Citations

Open accessJournal ArticleDOI: 10.3390/PLANTS9050660
23 May 2020-
Abstract: The effect of iron, manganese, phosphorus and nitrogen on growth and lipid synthesis of the microalgae Nannochloropsis oceanica CCMP1779, as well as their impact on the magnetic harvesting efficiency, are examined under their depriving cell culture conditions. Herein, it is demonstrated that nitrogen and manganese depletion primarily reduced cell growth while phosphorus and iron restriction led to higher dry biomass. Subsequently, the role of those nutrients on fatty acids profile was examined. Phosphorus and nitrogen restriction resulted in lower and higher lipid content, respectively. High amounts of polyunsaturated fatty acids like eicosapentaenoic acid are produced under iron and manganese depletion. Phosphorus deprivation favors monounsaturated fatty acids such as C18:1 and C16:1, while nitrogen restriction favors saturated fatty acid production like C14:0, C16:0 and C18:0. Since the presence/absence of macro- and micro-elements may affect the overall electrostatic charges on the outmost microalgae surface, it was also analyzed how these elements affect the magnetic harvesting efficiency. Results showed that phosphorus deprivation led to the best magnetic harvesting efficiency of N. oceanica cells (93%) as compared to other nutrient starvation as well as standard medium.

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Topics: Saturated fatty acid (62%), Polyunsaturated fatty acid (58%), Phosphorus (56%) ... read more

6 Citations


33 results found

Journal ArticleDOI: 10.1016/J.BIOTECHADV.2007.02.001
Yusuf Chisti1Institutions (1)
Abstract: Continued use of petroleum sourced fuels is now widely recognized as unsustainable because of depleting supplies and the contribution of these fuels to the accumulation of carbon dioxide in the environment. Renewable, carbon neutral, transport fuels are necessary for environmental and economic sustainability. Biodiesel derived from oil crops is a potential renewable and carbon neutral alternative to petroleum fuels. Unfortunately, biodiesel from oil crops, waste cooking oil and animal fat cannot realistically satisfy even a small fraction of the existing demand for transport fuels. As demonstrated here, microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Like plants, microalgae use sunlight to produce oils but they do so more efficiently than crop plants. Oil productivity of many microalgae greatly exceeds the oil productivity of the best producing oil crops. Approaches for making microalgal biodiesel economically competitive with petrodiesel are discussed.

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Topics: Renewable fuels (68%), Biodiesel (59%), Sustainable biofuel (58%) ... read more

8,281 Citations

Journal ArticleDOI: 10.1139/M62-029
Abstract: Bacteria-free clones of the small centric diatom Cyclotella nana Hustedt were isolated, three from estuarine localities, one from Continental Shelf waters, and one from the Sargasso Sea. Detonula confervacea was isolated from Narragansett Bay. Morphology of all clones was studied with the light and electron microscopes. Morphological differences between clones of C. nana do not at present warrant separating any as distinct species.Clones of C. nana require only vitamin B12; D. confervacea has no vitamin requirement.Growth of the estuarine clones of C. nana was unaffected by salinity down to 0.5‰ and increased with temperature to 25 °C. The Shelf clone grew more rapidly at salinities above 8‰ and at temperatures between 10° and 20 °C. The Sargasso Sea clone did not survive below 15 °C or 17.5‰, while D. confervacea did not survive at temperatures above 15° or at salinities below 8‰. The physiological differences between clones correspond roughly to the conditions obtaining in nature where each was collected.

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6,560 Citations

Open accessJournal ArticleDOI: 10.1016/J.RSER.2009.07.020
Abstract: Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO 2 , wastewater treatment, in human health, as food additive, and for aquaculture.

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Topics: Culture of microalgae in hatcheries (59%), Algae fuel (57%), Biofuel (53%) ... read more

4,597 Citations

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