Sonication of microalgae and its precipitation

The paper deals with experimental data concerning the interaction of acoustical waves with microbial cells, like microalgae. It is shown that low frequency ultrasound causes stronger cell destruction than high frequencies. It was also found that low frequency sound could precipitate the cells in highly concentrated suspensions. The mechanisms of cell destruction and cell precipitation are studied. The phenomenon of precipitation can be explained by dissolution of micro-bubble CO₂ (carbon dioxide) and removal of gas bubbles. Cell destruction by ultrasound waves results in cavitating small bubbles. The collapsing bubbles yield a rarefied zone near the cells and the latter explode.