Comparison of ceramic microfiltration and ultrafiltration membranes for the clarification of simulated sebacic acid fermentation broth

Sebacic acid, an important chemical intermediate, is usually prepared by fermentation. However, the composition of the fermentation broth is complex, which causes significant difficulties in the purification of the product and is still a key problem in the industry. In this study, the application of ceramic membranes for the separation and purification of simulated fermentation broth was studied. Ceramic microfiltration (MF) and ultrafiltration (UF) membranes with average pore sizes of 100 and 6 nm, respectively, were systematically compared by analyzing their separation effects on different components in the fermentation broth and their permeation flux during filtration. Both ceramic MF and UF membranes can be used to clarify the fermentation broth with turbidity less than 0.01 NTU by the effective removal of emulsified oil and bacteria while allowing sodium sebacate to pass through freely. However, the ceramic UF membrane showed a higher protein rejection of more than 95%, whereas the removal rate of the MF membrane was only approximately 20%. In addition, the fouling process of ceramic UF membrane was analyzed. In the suitable operating conditions when the pH was 9.2, the temperature was 60 ℃, the pressure was 0.1 MPa and the cross-flow velocity was 1.8 m·s⁻¹, the membrane fouling process was dominated by the reversible cake formation. A ceramic UF membrane with a smaller pore size can effectively avoid pollution in pore channels, and thus exhibits a higher permeation flux in the filtration of the fermentation broth.