Effects of surfactant contamination on oxygen mass transfer in fine bubble aeration process

The effects of anionic, cationic, and non-ionic surfactants (SDS, SDBS, CTAB and Tween20) on oxygen mass transfer (OMT) in fine bubble aeration systems were investigated. The overall gas-liquid volumetric mass transfer coefficient (K_La), specific interfacial area (a), and liquid-side mass transfer coefficient (K_L) parameters were used to assess the influence of the surfactants. At the same concentration, the different surfactants were observed to influence the K_La value as follows: K_La (SDBS)>K_La (SDS)>K_La (tween20)>K_La (CTAB). For all used surfactants, the overall trends showed a significant decrease in the K_La value at low concentrations (0-5mg/L), while the K_La value recovered somewhat at high concentrations (10-20mg/L). The decrease to the K_L value was found to be much larger than increase in the a value in the presence of surfactants. Furthermore, a simple model was established that provides an OMT prediction for different surfactants