Direct observation of membrane cleaning via rapid backpulsing

Direct visual observation (DVO) was used to view membrane surfaces at different times in crossflow microfiltration of yeast suspensions with rapid backpulsing at varied backpulsing duration and pressure. The DVO photos show that the membranes are more effectively cleaned by longer backpulse durations and higher backpulse pressures. However, a tradeoff exists, as longer and stronger backpulses also have greater permeate loss during each backpulse. The net flux was increased two-fold and four-fold with backpulsing under optimum conditions for 0.2 mum Anopore and cellulose acetate membranes, respectively, fouled by 0.05 g/L washed yeast cells. Shorter, stronger backpulses resulted in higher net fluxes than did weaker, longer backpulses after 2 h of filtration.