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Biocrude Oil Production by Integrating Microalgae Polyculture and Wastewater Treatment: Novel Proposal on the Use of Deep Water-Depth Polyculture of Mixotrophic Microalgae

1
MoBiol Technologies Corporation, 1155-50 Kakioka, Ishioka 315-0116, Ibaraki, Japan
2
ABES, Faculty of Life and Environment Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8572, Ibaraki, Japan
*
Author to whom correspondence should be addressed.
Academic Editor: Alberto-Jesus Perea-Moreno
Energies 2021, 14(21), 6992; https://doi.org/10.3390/en14216992
Received: 8 September 2021 / Revised: 19 October 2021 / Accepted: 20 October 2021 / Published: 25 October 2021
(This article belongs to the Section H1: Fuel)
Microalgae have attracted significant attention worldwide as one of the most promising feedstock fossil fuel alternatives. However, there are a few challenges for algal fuels to compete with fossil fuels that need to be addressed. Therefore, this study reviews the R&D status of microalgae-based polyculture and biocrude oil production, along with wastewater treatment. Mixotrophic algae are free to some extent from light restrictions using organic matter and have the ability to grow well even in deep water-depth cultivation. It is proposed that integrating the mixotrophic microalgae polyculture and wastewater treatment process is the most promising and harmonizing means to simultaneously increase capacities of microalgae biomass production and wastewater treatment with a low land footprint and high robustness to perturbations. A large amount of mixotrophic algae biomass is harvested, concentrated, and dewatered by combining highly efficient sedimentation through flocculation and energy efficient filtration, which reduce the carbon footprint for algae fuel production and coincide with the subsequent hydrothermal liquefaction (HTL) conversion. HTL products are obtained with a relatively low carbon footprint and separated into biocrude oil, solid, aqueous, and gas fractions. Algae biomass feedstock-based HTL conversion has a high biocrude oil yield and quality available for existing oil refineries; it also has a bioavailability of the recycled nitrogen and phosphorus from the aqueous phase of algae community HTL. The HTL biocrude oil represents higher sustainability than conventional liquid fuels and other biofuels for the combination of greenhouse gas (GHG) and energy return on investment (EROI). Deep water-depth polyculture of mixotrophic microalgae using sewage has a high potential to produce sustainable biocrude oil within the land area of existing sewage treatment plants in Japan to fulfill imported crude oil. View Full-Text
Keywords: mixotrophic algae; polyculture; wastewater treatment; HTL; biocrude; nutrient recovery mixotrophic algae; polyculture; wastewater treatment; HTL; biocrude; nutrient recovery
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MDPI and ACS Style

Watanabe, M.M.; Isdepsky, A. Biocrude Oil Production by Integrating Microalgae Polyculture and Wastewater Treatment: Novel Proposal on the Use of Deep Water-Depth Polyculture of Mixotrophic Microalgae. Energies 2021, 14, 6992. https://doi.org/10.3390/en14216992

AMA Style

Watanabe MM, Isdepsky A. Biocrude Oil Production by Integrating Microalgae Polyculture and Wastewater Treatment: Novel Proposal on the Use of Deep Water-Depth Polyculture of Mixotrophic Microalgae. Energies. 2021; 14(21):6992. https://doi.org/10.3390/en14216992

Chicago/Turabian Style

Watanabe, Makoto M., and Andreas Isdepsky. 2021. "Biocrude Oil Production by Integrating Microalgae Polyculture and Wastewater Treatment: Novel Proposal on the Use of Deep Water-Depth Polyculture of Mixotrophic Microalgae" Energies 14, no. 21: 6992. https://doi.org/10.3390/en14216992

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