Hydrothermal liquefaction of harvested high-ash low-lipid algal biomass from Dianchi Lake: Effects of operational parameters and relations of products

Abstract

Hydrothermal liquefaction (HTL) allows a direct conversion of algal biomass into biocrude oil, not only solving the environmental issues caused by the over-growing algae but also producing renewable energy. This study reports HTL of algae after separation from eutrophicated Dianchi Lake in China. Conversion efficiency was studied under different operational conditions via an orthogonal design, including holding temperature (HT) (260–340°C), retention time (RT) (30–90min) and total solid (TS) (10–20%). A highest biocrude oil yield (18.4%, dry ash-free basis, daf) was achieved at 300°C, 60min, and 20% (TS), due to the low contents of lipids (1.9%, daf) and proteins (24.8%, daf), and high contents of ash (41.6%, dry basis) and carbohydrates (71.8%, daf). Operational parameters significantly affected the biocrude yields, and chemical distribution of HTL products. The biocrude production also related to other HTL products, and involved chemical reactions, such as deoxygenation and/or denitrogenation.