Direct visual observation of yeast deposition and removal during microfiltration

Periodic reverse flow through membranes is an effective technique to remove foulants from microfiltration (MF) membrane surfaces. This work explored direct visual observation (DVO) of yeast deposition and subsequent removal via backwashing and single backpulses using microvideo photography with cellulose-acetate (CA) and Anopore anodised-alumina (AN) MF membranes. Foulant deposited less uniformly on the surfaces of the CA membranes than on the AN membrane surfaces during forward filtration. Foulant cake layers of approximately 30 μm thickness formed on both membranes after forward filtration for 1–2 h, leading to fouled-membrane fluxes of only 15–25% of the clean-membrane fluxes.