Volumetric mass transfer coefficient (kLa) study with Pressure Swing Rotating Bubble Cap (PSRBC) sparger in a semi-batch bubble column

The present investigation is focused on evaluating the effect of sparger rotation on the mass transfer performance in terms of volumetric mass transfer coefficient ( k L a ) in a semi-batch Bubble Column equipped with a Pressure Swing Rotating Bubble Cap (PSRBC) sparger. In semi-batch mode operation, compressed air was introduced through the PSRBC sparger into the stationary water column, where the variation of dissolved oxygen (DO) concentration with time at varied liquid heights (H l ) and superficial air velocities (v sa ) was monitored utilizing a DO meter. Experimental values were measured at regular time intervals to determine the k L a and also to develop predictive empirical correlations for DO concentration under both static and rotating PSRBC configurations. The results clearly manifest that rotation of the PSRBC sparger promotes enhanced air dispersion and more uniform bubble distribution throughout the liquid volume, resulting in a higher oxygen dissolution rate compared with the static configuration. The empirical model equations developed for the DO concentration prediction with the PSRBC sparger have exhibited close agreement with the experimental findings, with a correlation coefficient exceeding 0.98. The k L a for the rotational PSRBC sparger was found to be up to 16% greater than that obtained from the stationary configuration in the present range of investigation. Thus, mass transfer in bubble column can be significantly enhanced by the controlled sparger rotation. The outcomes of the current investigation highlight the potential insights for the design of sparged vessels, including bubble columns, deaerator tanks, and bioreactors, where DO is an intricate parameter influencing overall process performance.