TUBULAR MEMBRANE FILTRATION FOR LIME SOFTENING WATER TREATMENT

摘要

High levels of silica and total hardness are problematic for applications requiring large amountsof water reuse, or in a zero liquid discharge (ZLD) system. This includes the reuse of coolingtower blow-down water and other influent streams that may feed an RO system as part of arecycling process. Scaling and other issues can render a system ineffective if not addressed aspart of the process.Tubular Membrane Filtration (TMF) is an alternative to traditional settling methods and mayoffer advantages, particularly in cases of high levels of silica and hardness. The effectiveness ofTMF compared to a gravity clarification model is discussed in this paper.The TMF system used in this comparison is a cross-flow designed tubular composite filtrationmedia comprised of a sintered porous plastic supporting structure with PVDF membrane. ThePVDF membrane is embedded in the sintered porous plastic matrix and covers the internalsurface of the sintered porous plastic tube. The module made from this composite tubularfiltration media shows high efficiency for water treatment with high solids content (typically 3-5%, but can go as high as 18%).