Ultrasound enhanced ethanol production from Parthenium hysterophorus: A mechanistic investigation

• Mechanistic investigations in ultrasonic bioethanol fermentation using SHF mode.
• Approach of coupling experimental results to mathematical model.
• 2-Fold enhancement in productivity of ethanol and cell mass with ultrasound.
• Model parameters give mechanistic insight into effect of ultrasound.
• Beneficial effect of ultrasound due to generation of strong micro-turbulence.

This study presents mechanistic investigations in ultrasound-assisted bioethanol fermentation using Parthenium hysterophorus biomass. Ultrasound (35 kHz, 10% duty cycle) has been used for sonication. Experimental results were fitted to mathematical model; the kinetic and physiological parameters in the model were obtained using Genetic Algorithm (GA) based optimization. In control experiments (mechanical shaking), maximum ethanol titer of 10.93 g/L and cell mass concentration of 5.26 g/L was obtained after 18 h. In test experiments (mechanical shaking and intermittent sonication), ethanol titer of 12.14 g/L and cell mass concentration of 5.7 g/L was obtained in 10 h. This indicated ∼2× enhanced productivity of ethanol and cell mass with sonication. Trends in model parameters obtained after fitting of model to experimental data essentially revealed that beneficial influence of ultrasound on fermentation is a manifestation of enhanced trans-membrane transportation and dilution of toxic substances due to strong micro-convection induced by ultrasound.