Bio-based flocculants for sustainable harvesting of microalgae for biofuel production. A review

Ogbonna, Christiana N.; Nwoba, Emeka G.

doi:10.1016/j.rser.2020.110690

Cited by 98 publications

(31 citation statements)

References 109 publications

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“…Microalgae flocculation can also occur naturally caused by extracellular polymers and/or info-chemicals secreted into the medium, and this is called bio-flocculation [49], with some species flocculating more readily than others [50]. Info-chemicals have been identified in terrestrial plants such as methyl jasmonate that signal herbivorous attack between plants [51].…”

Section: Flocculationmentioning

confidence: 99%

Key Targets for Improving Algal Biofuel Production

et al. 2021

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A number of technological challenges need to be overcome if algae are to be utilized for commercial fuel production. Current economic assessment is largely based on laboratory scale up or commercial systems geared to the production of high value products, since no industrial scale plant exits that are dedicated to algal biofuel. For macroalgae (‘seaweeds’), the most promising processes are anaerobic digestion for biomethane production and fermentation for bioethanol, the latter with levels exceeding those from sugar cane. Currently, both processes could be enhanced by increasing the rate of degradation of the complex polysaccharide cell walls to generate fermentable sugars using specifically tailored hydrolytic enzymes. For microalgal biofuel production, open raceway ponds are more cost-effective than photobioreactors, with CO2 and harvesting/dewatering costs estimated to be ~50% and up to 15% of total costs, respectively. These costs need to be reduced by an order of magnitude if algal biodiesel is to compete with petroleum. Improved economics could be achieved by using a low-cost water supply supplemented with high glucose and nutrients from food grade industrial wastewater and using more efficient flocculation methods and CO2 from power plants. Solar radiation of not <3000 h·yr−1 favours production sites 30° north or south of the equator and should use marginal land with flat topography near oceans. Possible geographical sites are discussed. In terms of biomass conversion, advances in wet technologies such as hydrothermal liquefaction, anaerobic digestion, and transesterification for algal biodiesel are presented and how these can be integrated into a biorefinery are discussed.

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Section: Flocculationmentioning

confidence: 99%

Key Targets for Improving Algal Biofuel Production

et al. 2021

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“…When flocculants are added into the microalgae culture medium, the surface charge is blocked so that microalgae cells can adhere to form stable flocs. The flocculants utilized must be low-cost, nontoxic, and effective in low application doses [84]. Several chemicals are identified to be utilized as flocculants for this purpose.…”

Section: Harvesting Of Microalgaementioning

confidence: 99%

Food Industries Wastewater Recycling for Biodiesel Production through Microalgal Remediation

et al. 2021

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This article is an overview of a biosystem of food-industry wastewater (WW) treatment using microalgae towards circular bioeconomy through biosynthesis of compounds of added-value. Focusing on circular bioeconomy with concern to environmental pollution, the management of water-resource and energy-crisis could be combined; by upgrading conventional WW treatment and simultaneously producing a renewable and sustainable source of energy algal-lipids for biodiesel production. Phyco-remediation of food WW using microalgae has revealed many advantages that can fulfill new demands for the WW treatment. WWs can be valuable resources of micronutrients and organic content (carbon source) for algal cultivation. In this review, prospective routes for the production of value-added compounds (polysaccharides, amino acids, biofuels, and biopigments) along with the bioremediation of food industry WW have been discussed. Furthermore, limitations and issues of phyco-remediation of WW using microalgae have also been reviewed with perspectives for further research and development.

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“…However, they also underlined that its commercialization is challenging for a while. Ogbonna and Nwoba [77] proposed bio-based flocculants for producing microalgae-based biofuels. They compared chitosan, aluminum sulfate, and Moringa oleifera.…”

Section: Algae-based Ethanol Productionmentioning

confidence: 99%

Economic Aspects and Sustainability of Ethanol Production—A Systematic Literature Review

Mizik

2021

Energies

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Meeting the increasing global energy demand in a sustainable way is a major challenge for humanity. One of the solutions in the transportation sector is ethanol, which is currently the only economically viable direct fuel substitute. In addition to the first-generation technology, which provides the vast majority of production, better results can be continuously realized by using advanced technologies. This study aims to investigate the economic aspects and sustainability issues of ethanol production with a systematic literature review. During the selection process, 64 studies from a total of 16,141 identified articles were analyzed in-depth. There is a consensus that first-generation production methods cannot result in a long-term solution. However, advanced technologies are currently immature, and ethanol production is more expensive with them. The use of wastes/residues and coproducts can improve both the economic outlook and sustainability of the advanced technologies. Overall, the newer generations of technological advancements are constantly improving the environmental performance, whereas the economic performance is deteriorating. Considering low oil prices (0.36 USD/L), none of the ethanol production methods can be competitive on a purely cost basis. This increases the importance of coproducts (further processing and more valuable coproducts). Regarding sustainability, a complex analysis is essential, which must cover at least the environmental, social, and economic aspects. At the methodology level, a complex life cycle analysis seems to be the best tool, as it can take into account these relevant aspects (environmental, economic, and social).

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Bio-based flocculants for sustainable harvesting of microalgae for biofuel production. A review

Cited by 98 publications

References 109 publications

Key Targets for Improving Algal Biofuel Production

Key Targets for Improving Algal Biofuel Production

Food Industries Wastewater Recycling for Biodiesel Production through Microalgal Remediation

Economic Aspects and Sustainability of Ethanol Production—A Systematic Literature Review

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