The influence of particles on biofouling behavior in spiral wound membrane elements

Spiral-wound membrane (SWM) elements for nanofiltration (NF) and reverse osmosis (RO) need pre-treatment to prevent clogging of the feed spacer channel by particles and/or biomass. Usually rapid sand filtration or ultrafiltration is applied for this purpose. The effect of (the removal of) particles on biofouling processes in spiral-wound membrane (SWM) elements was investigated in this work by using a pilot set-up consisting of three parallel SWM elements. Local tap water supplemented with acetate to promote biofouling was fed to (i) a reference element, (ii) an element with one hour of daily dosing of copper sulfate to control biofouling and (iii) a third element with an additional pre-filtration to eliminate particles from the feed water of the element. The additional filter element behaved similarly to the reference element with respect to membrane transfer coefficient (MTC) decrease and pressure drop increase. Also results for membrane autopsy for biological and organic parameters were similar. The results demonstrated that the applied particle removal did not have a significant effect on the biofouling behavior in SWRO elements.