Comparison of the efficiency of pulsed flow membrane cleaning in hollow fibre (HFM) and spiral-wound microfiltration membranes (SWM)

Abstract

Membrane cleaning is a particular issue for spiral-wound membranes (SWM), as their cleanability is limited due to spacer-induced flow shadows behind spacer filaments. One option to enhance membrane cleaning efficiency is applying pulsed flow, characterised by a cyclic transition between high and low flow rates. This study examined how the cleaning success in hollow fibre membranes (HFM) and spiral-wound membranes (SWM) can be enhanced by pulsed flow at varying concentrations of the cleaning agent NaOH. The cleaning success was determined by protein removal and flux recovery analyses as well as scanning electron microscopy (SEM) imaging of cleaned membrane surfaces. The highest increase in cleaning efficiency as a result of pulsed flow was found for SWM at cNaOH = 0.03% (pH 11.3), where protein removal was increased by 48% over steady flow cleaning. SEM analyses confirmed that this was due to the pulsation-induced turbulence allowing improved access to spacer-induced flow shadows. Overall, cleaning success with pulsed flow at cNaOH = 0.03% could be improved in both HFM and SWM over that of steady flow at cNaOH = 0.30%, implying distinct reductions in chemicals consumption or shortened cleaning times when applying pulsed flow.