Carboxymethyl cellulose protects algal cells against hydrodynamic stress

The harmful effect of direct air sparging on Phaeodactylum tricornutum micr oalgal cultures was investigated in bubble columns and airlift photobioreac tors with various superficial air velocities and two types of spargers, whi ch generated different sizes of bubbles. Small bubbles bursting at the surf ace of the culture were apparently the main cause of cell damage in batch c ultures in laboratory-scale bubble columns. Other mechanisms of cell damage also were a contributing factor to the observed cell loss in outdoor pilot -scale bubble columns. Supplementation of the microalgal culture medium wit h carboxymethyl cellulose at concentrations of 0.02% and greater is shown t o protect the algal cells against aeration-induced hydrodynamic stress. (C) 2001 Elsevier Science Inc. All rights reserved.