Dilute acid hydrolysis of microalgal biomass for bioethanol production: an accurate kinetic model of biomass solubilizaion, sugars hydrolysis and nitrogen/ash balance

In this paper, acidic hydrolysis (0–5 vol%) was performed on Chlorella vulgaris biomass using a range of temperature (100–130 C) and reaction time (0–60 min) with high biomass load (10%—100 g L-1), in order to characterize the kinetic of biomass solubilization, hydrolysis of sugars, proteins and ash release, and to verify the main divergences and similarities in relation to lignocellulosic biomass. More than 90% of the sugars present in the biomass was hydrolyzed and later satisfactorily fermented by S. cerevisiae. The inclusion of acid concentration in the kinetic model for biomass solubilization and sugar hydrolysis led to a modified Michaelis–Menten equation able to simulate efficiently the acidic extraction/hydrolysis data of all experimental runs. Main divergences in relation to lignocellulosics were related to higher reaction order and lower activation energy, reveling better susceptibility of microalgal biomass to acidic treatment. The proposed process is promising and can be easily scaled up at industrial level.