Improved production and quality of biocrude oil from low-lipid high-ash macroalgae Enteromorpha prolifera via addition of crude glycerol

Enteromorpha prolifera (Ep), a dominant low-lipid marine macroalgae with about 30% ash content, is seasonally bloomed along the coast of eastern China, whereas crude glycerol is a main byproduct of biodiesel industry. This study focused on the biocrude production from Ep with crude glycerol, in comparison to those from Ep alone, and Ep with glycerol at different reaction temperatures (240 °C −360 °C). The highest biocrude yield of 38.71% was obtained at 320 °C using Ep with crude glycerol (mass ratio: 1:6), which was much higher than those using Ep alone (13.35%) and Ep with glycerol (16.14%) at the same ratios. After the optimization of the mass ratio of Ep to crude glycerol and retention time, the highest biocrude yield further reached 47.28% at a mass ratio (Ep to crude glycerol) of 1:5 and a retention time of 50 min. The addition of crude glycerol significantly improved biocrude production as well as reduced the oil nitrogen content. Elemental analysis indicated the nitrogen contents of biocrude oil from Ep with crude glycerol were nearly less than 1%, much lower than those under other conditions and similar to that of petroleum. This study suggested that the addition of crude glycerol could improve the yield and quality of the biocrude oil from eutrophic low-lipid high-protein algae.