Hydrodynamic cavitation for energy efficient and scalable process of microalgae cell disruption

Abstract

Microalgae are likely to emerge as a sustainable source of biomass which can be utilized as food, feed, and fuel. Most of the valuable products in the microalgae are present intracellular. Microalgae cell wall is rigid and mainly composed of cellulose. Hence, it is essential to disrupt cells to extract intracellular products. Probe ultrasonication (US) and hydrodynamic cavitation (HC) were optimized for their operating parameters and various pre-treatments to obtain maximum cell disruption efficacy. Optimum conditions for maximum cell disruption using US were: solid load (1% w/v), duty cycle (80%), power input (54 W) and the US time 90 min. After pre-treatment with 0.5% w/v sodium hydroxide; the time required for the maximum cell disruption using US was reduced to 50 min. Optimum conditions for the maximum cell disruption using HC were cavitation device orifice over venturi, time (180 min), pressure (5 bar) and solid load (0.45% w/v). After pre-treatment with 0.5% w/v sodium hydroxide time required for maximum cell disruption using HC was reduced to 105 min. Further, the energy required for cell disruption using US and HC was calculated and, it was found that HC was significantly more energy efficient and scalable treatment for microalgae cell disruption.