Biocrude Oil from Algal Bloom Microalgae: A Novel Integration of Biological and Thermochemical Techniques

Jamison Watson, Megan Swoboda, Aersi Aierzhati, Tengfei Wang, Buchun Si, Yuanhui Zhang

Research output: Contribution to journalArticlepeer-review


Algal bloom microalgae are abundant in polluted water systems, but their biocrude oil production potential via hydrothermal liquefaction (HTL) is limited. This study proposed a novel process that combined biological (dark fermentation) and thermochemical (HTL) techniques aimed at changing the feedstock characteristics to be more suitable for thermochemical conversion, herein named integrated dark fermentation-hydrothermal liquefaction (DF-HTL). DF-HTL conversion of algae significantly enhanced the biocrude oil yield (wt %), carbon content (mol), energy content (MJ), and energy conversion ratios by 9.8, 29.7, 40.0, and 61.0%, respectively, in comparison to the control. Furthermore, DF-HTL processing significantly decreased the aqueous byproduct yield (wt %), carbon content (mol), nitrogen content (mol), and ammonia content (mol) by 19.0, 38.4, 25.0, and 13.2%, respectively, in comparison to the control. Therefore, DF-HTL reduced the environmental impact associated with disposing of the wastewater byproduct. However, DF-HTL also augmented the nitrogen content (mol) of the biocrude oil by 42.2% in comparison to the control. The benefits of DF-HTL were attributed to the increased acid content, the incorporation of H2 as a processing gas, and the enhancement of the Maillard reaction, which shifted the distribution of reaction products from the aqueous phase to the biocrude oil phase. This article provides insights into the efficacy of a novel integrated biological-thermochemical processing method with distinct environmental and energetic advantages over conventional HTL that heightens the biocrude oil yield for feedstocks with a high carbohydrate and a high protein content.

Original languageEnglish (US)
Pages (from-to)1973-1983
Number of pages11
JournalEnvironmental science & technology
Issue number3
StatePublished - Feb 2 2021

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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