Microfiltration of biomass and biofluids: Effects of membrane morphology and operating conditions

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Abstract
Fundamental studies carried out at the Centre for Membrane and Separation Technology (Australia) considered the effect of membrane surface properties and ionic strength using biomass microfiltration on controlled suspensions of Escherichia Coli . Anopore, Nuclepore and Millipore (hydrophilic and hydrophobic) membranes of similar pore size (0.2 μm) were characterised and subjected to flux tests with E.Coli suspension at different ionic strengths and transmembrane pressures. Membrane recovery after shear was also monitored and analysis using Scanning Electron Microscopy was performed on the cake formation. It was found that both ionic strength and membrane surface properties affected flux significantly and influenced recovery. The more porous and smooth hydrophilic Anopore membrane returned higher fluxes than the less porous Nuclepore and the rough Millipore membranes. High ionic strength solutions resulted in lower fluxes which can be explained using the colloid double-layer theory. Membrane recovery was easier for low pressure operation and low ionic strength suspensions.