Recent advances in ultrasound-assisted technologies for improved bioproduct recovery in lignocellulosic and microalgal biorefineries

Ultrasound irradiation is a promising green technology that facilitates waste biomass fractionation, contributing to the net zero carbon emissions and a sustainable circular economy. The current review underscores the role of ultrasound as a complementary technique to the existing biomass pretreatment methods that triggers thermochemical reactions, leading to improved bioproducts recovery. The cavitation effects of ultrasound such as shock waves and microjets, which enhance structural modifications in the waste biomass are highlighted. The green pretreatment methods assisted by ultrasonication could improve the rate of enzymatic hydrolysis up to 40% and achieve lignin removal rates by nearly 80%. Further, it boosts lipid extraction from microalgal biomass by 150% and improves carbohydrate recovery by over 50%, highlighting its potential to disrupt cell walls effectively. The review also emphasizes on the life cycle assessment of ultrasound-assisted processes that offers significant advantages, including improved biomass conversion efficiency, lower energy consumption, and compatibility with green solvents.