Throughout the module, Membrana’s UltraPES™ membrane is stabilized by its Multifiber P.E.T.®Technology. Groups of hollow fiber membranes are interlaced with a robust PET yarn, which is potted together with the membranes. This provides additional mechanical strength for the hollow-fiber in the axial direction as well as during backflushing when the fibers can experience some flexing . At the same time hydrodynamics during the back wash is improved as the yarn acts as spacer between small bundles of hollow fiber membranes. This ensures better access for the flushing water to reach all areas of the membrane sections even in the central area of a membrane segment.