Zero emissions system for fossil fuel desulfurization using Gordonia alkanivorans strain 1B

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Towards a zero emission system for liquid fuel desulfurization using Gordonia alkanivorans strain 1B

Publication . Silva, Tiago P.; Alves, Luís Manuel Gonçalves; Alves, Susana Maria Teixeira Paixão; Chambel, Lélia Mariana Marcão

Current desulfurization technologies are inefficient at dealing with complex sulfur-containing molecules abundant in many liquid fuels. Biodesulfurization is an alternative/complementary method that employs microorganisms as biocatalysts, targeting the sulfur contained in complex molecules at ambient conditions, without damaging fuel quality. However, biocatalyst production is expensive, biodesulfurization activity is low and inhibited by easy-access sulfur sources, requiring substantial amounts of biocatalysts and complex processing. Furthermore, most studies do not account for the applicability of the proposed methods, thus hindering the integration with fuel production. For biodesulfurization to be successfully implemented, it must be conjugated with the production of high-added value products to compensate the added costs. This work was centered on the biodesulfurizing bacterium Gordonia alkanivorans strain 1B and has the objective of developing a sustainable continuous biodesulfurization system, accounting for all process steps, from biocatalyst production to fuel separation, as well as potential by-product valorization. Results demonstrated that strain 1B can produce carotenoids and biosurfactant/bioemulsifier compounds, which can be targeted as high-added value products for the valorization of spent biomass and depleted culture medium, respectively. Additionally, it was possible to design a novel biodesulfurization system, that included continuous biocatalyst production using easy-access sulfur sources, while avoiding inhibition, directly integrated with continuous fuel biodesulfurization and separation. This allowed strain 1B to achieve its highest biodesulfurization rates, as well as 72 % desulfurization of a recalcitrant model fuel in <72 h, and sulfur reduction in two crude oils and a tire/plastic pyrolysis oil. Lastly, a continuous autotrophic photobioreactor was developed for the continuous sequestration of produced CO2, using the microalga Haematococcus pluvialis. This resulted in a process design that combines continuous biodesulfurization with valorization of spent biomass, depleted culture medium and produced CO2, potentially transforming desulfurization into an increased value bioprocess, making the production of fuels cleaner and more sustainable.

2024-03Tese de doutoramento

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Fundação para a Ciência e a Tecnologia

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SFRH/BD/104977/2014