Abstract:

The clarification of L-lactic acid containing fermentation supernatant by ultrafiltration is an important pretreatment step for the separation of L-lactic acid. In this study, spiral-wound membrane modules with molecular weight cut-offs (MWCO) of 1000 D and 3000 D were used to filtrate the L-lactic acid containing supernatant derived from Rhizopus oryzae AS3.819 fermentation, and the one with 3000 D MWCO was selected for the subsequent investigations due to larger membrane flux, in which, 4 process conditions (i.e., ultrafiltration time, operation pressure and temperature and protein concentration) affecting the membrane flux of the selected module were explored and a mathematical model was developed describing the relationship of the function with operation pressure and protein concentration. The membrane flux of the spiral-wound membrane module with 3000 D MWCO attenuated with prolonged ultrafiltration time and increasing protein concentration, but elevated with increasing operation pressure and temperature. The developed model revealed good reliability in predicting the membrane flux of the spiralwound membrane module with 3000 D MWCO.

Key words: L-lactic acid fermentation supernatant ultrafiltration, membrane flux, mathematical model