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

Increasing Performance of Spiral-Wound Modules (SWMs) by Improving Stability against Axial Pressure Drop and Utilising Pulsed Flow

“…With pulsed flow improving access to flow shadows [29,31,44,51,[55][56][57][58][59] and thus improving removal particularly in these areas, the reason for the absence of improvements in FRR could be due to the steady water flux measurements being prone to the same flow shadows behind spacer filaments as steady flow cleaning. As shown in a previous study for FSMs, fouling residues in areas subject to flow shadows could only partially be removed by steady flow cleaning, whereas no distinct residues in those areas could be observed for pulsed flow cleaning [29]. As these observations were only reflected by an increased protein removal but not an increase in FRR, it can be assumed that the additional protein removal near Regarding FRR, there were no significant differences between flow modes, with 90 ± 2% for steady and 87 ± 5% for pulsed flow.…”

“…Compared to CTMs and HFMs, SWMs offer the highest packing density, i.e., active membrane area per module, and thus the highest whey protein mass flow per module [ 28 ]. On the contrary, SWMs suffer from flow shadows behind spacer filaments [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ] and, therefore, limited cleanability [ 29 ] and mechanical stability. In SWMs, the membrane permeate pockets are formed by glueing together individual membrane sheets, which are then wrapped around a central permeate collection tube and fixed by an outer hull.…”

“…One example is applying pulsed flow, i.e., a non-steady flow defined by its amplitude, in other words the difference between maximum and minimum flow and pressure conditions, and its frequency. Several studies demonstrated the positive influence of pulsed flow on filtration [ 31 , 43 ] and cleaning performance [ 29 , 44 ] for various feed solutions, including milk. For membranes containing spacers, such as SWMs, particularly strong effects of pulsed flow on filtration and cleaning performance were reported due to pulsed flow reducing flow shadows due to enhanced turbulence [ 29 , 31 ] at high frequencies [ 44 , 45 , 46 , 47 , 48 , 49 ] and amplitudes [ 44 , 45 , 46 , 47 , 49 ].…”

“…Several studies demonstrated the positive influence of pulsed flow on filtration [ 31 , 43 ] and cleaning performance [ 29 , 44 ] for various feed solutions, including milk. For membranes containing spacers, such as SWMs, particularly strong effects of pulsed flow on filtration and cleaning performance were reported due to pulsed flow reducing flow shadows due to enhanced turbulence [ 29 , 31 ] at high frequencies [ 44 , 45 , 46 , 47 , 48 , 49 ] and amplitudes [ 44 , 45 , 46 , 47 , 49 ].…”

“…However, some aspects exacerbate the transferability of lab-scale results to industrial-scale SWM modules. Firstly, the approaches to pulsation creation used in previous lab-scale studies either included piston or bellows units [ 45 , 50 ] or specialised inductively controlled pumps that could create pulsed flow by rapidly increasing and decreasing pump capacity [ 29 , 31 , 44 ]. The former approach temporarily induced distinct back-pressure and is thus incompatible with SWMs.…”