Wagner2018_Article_HydrothermalConversionOfLipid-.pdf (843.09 kB)
Download file

Hydrothermal conversion of lipid-extracted microalgae hydrolysate in the presence of isopropanol and steel furnace residues

Download (843.09 kB)
journal contribution
posted on 15.10.2018, 10:38 by Jonathan WagnerJonathan Wagner, Julio Perin, Renato S. Coelho, Valeska P. Ting, Christopher J. Chuck, Telma Teixeira Franco
Purpose Microalgae have a high potential as a feedstock for the production of biofuels, either indirectly, through the extraction of lipids, which can be transformed into biodiesel, or directly via whole cell conversion using hydrothermal liquefaction (HTL). Both approaches have disadvantages, due to the high cost of cultivating microalgae with sufficient lipid content (>40%), while the whole cell conversion produces low quality oils, which require significant further upgrading. This work investigated the possibility of realising the benefits of both processes, by studying the liquefaction reaction of a lipid-extracted algae hydrolysate. Methods In order to enhance oil yields, the reaction was conducted in the presence of varying loadings of iso-propyl alcohol (IPA) and applied two waste steel furnace residues as potential liquefaction catalysts. Results Primarily, The lipid extraction process needs to be optimized to reduce the amount of acid contaminant within the liquefaction medium. For the HTL process, the addition of 50 vol% IPA resulted in remarkably high oil yields of up to 60.2 wt% on an organic basis, whereas the two furnace residues had no positive effect on the product distribution, and instead favoured the formation of solid reaction products. Nevertheless, the results suggested that the presence of iron potentially reduced the nitrogen and oxygen content of the bio-oil. Conclusions As such, HTL is a suitable method for valorising lipid-extracted algal biomass, where the bio-oil yields can be enhanced substantially by using IPA in conjunction with the water.


This work was funded by the Engineering and Physical Sciences Research Council (EP/G03768X/1) and the University of Bath Global Research Scholarship Scheme.



  • Aeronautical, Automotive, Chemical and Materials Engineering


  • Chemical Engineering

Published in

Waste and Biomass Valorization


WAGNER, J.L. ... et al, 2017. Hydrothermal conversion of lipid-extracted microalgae hydrolysate in the presence of isopropanol and steel furnace residues. Waste and Biomass Valorization, 9 (10), pp.1867–1879.


Springer Netherlands © The Author(s)


VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date


Publication date



This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.