Clarification of raw rice wine by ceramic microfiltration membranes and membrane fouling analysis

Ceramic membrane capacity during the filtration of raw rice wine is typically limited by fouling, which can occur by pore blocking, pore constriction or caking. In this study three modified fouling models were used to describe flux decline behavior during microfiltration accounting for these three classical fouling mechanisms. The fouling mechanism was identified by estimation of the model parameter according to a nonlinear regression optimization procedure. Analysis by the models indicated cake filtration to be the dominant mechanism and pore constriction to be the secondary fouling mechanism. In the fixed operating conditions of transmembrane pressure (TMP) and cross-flow velocity (CVF), the fouling mechanism evolves from a pore constriction to a cake filtration. Membrane fouling was also investigated using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). FTIR analysis revealed that polysaccharides, long chain protein and some phenolics appear to be primarily responsible for fouling. The main physico-chemical characteristics of rice wine were evaluated in order to select membrane pore size and material that supply the highest permeation flux and best clarified rice wine.