Backwashing of tubular ceramic microfilters fouled with milk protein isolate feeds

Abstract

The effect of BW upon the operational performance of a tubular ceramic membrane was investigated for the MF of a high solids content (15 wt %) MPI feed inoculated with Bacillus mycoides spores. Three tubular ceramic Membralox™ (Pall Filtration, Bazet, France) MF membranes of pore sizes 0.8, 2.0 and 12.0 μm pore diameters were tested. A 10-s backflush every 5 min was found to be the most effective protocol during filtration experiments. Membrane cleaning using a combination of a long rinsing backflush at 1 bar, and acid and alkali steps without BW were found to be most effective after MPI filtration. Application of this protocol resulted in a flux recovery of 99.6%. PRACTICAL APPLICATIONS Pasteurization is an energy intensive process that can also affect the organoleptic properties of milk and dairy products. MF offers the possibility of replacing a thermal process with a physical (size exclusion) based one and is particularly attractive when the bacterial removal challenge involves thermophiles that resist heat treatment. While the application of MF for filtering low viscosity diary feeds is relatively well established, the filtration of high solids content, high viscosity feeds has not become well established because of low fluxes and poor transmission of solids. This article extends previous work in our laboratory that demonstrated the viability of this technology for bacterial removal from high solids content diary feeds. Here, the effect of membrane BW during both filtration and cleaning cycles is quantified, and a BW protocol is optimized. This is essential information for the practical operation of a membrane unit for this filtration application. © 2012 Wiley Periodicals, Inc.