Abstract
Biofouling of spiral-wound nanofiltration and reverse osmosis membranes was investigated. In-situ visual observations on fouling accumulation using the Membrane Fouling Simulator (MFS) window and in-situ observations on fouling accumulation and velocity distribution profiles using Magnetic Resonance Imaging (MRI) was performed. Full-scale and test-rig investigations showed that measurements of biological parameters in the water were not appropriate to quantify biofouling. Biofouling was a feed spacer channel problem. Biofouling on the feed spacer rather than the membrane itself caused most of the feed channel pressure drop increase. The results showed that restricted biomass accumulation on the feed spacer already had a strong impact on the flow velocity profile.