Effect of different contaminants on the α-factor: Local experimental method and modeling

Abstract

In this present paper, the effect of different contaminants (single and mixture) on the variation of α-factor (a ratio of processing water to clean water volumetric mass transfer coefficients, or k L a Process water/ k L a Clean water) was investigated. Tap water and aqueous solutions with surfactants, NaCl, glucose and inert microorganism were chosen as liquid phases and an elastic membrane with a single orifice as gas sparger. This study has clearly shown that the presence of these contaminants affects the bubble generation phenomenon, the interfacial area ( a) and the different mass transfer parameters, such as the volumetric mass transfer coefficient ( k L a) and the liquid-side mass transfer coefficient ( k L). The contamination of surfactants, even in small quantities, has shown the most significant effects. The determination of the α-factor in terms of interfacial area ( α a) and k L coefficient ( α k L ) was applied to understand details of the differences of the overall α-factor. The liquid surface tension and the α-factor as α a and α k L prove to be crucial for predicting the changes of α-factor in the mixture of various contaminants.