Microfiltration Membrane Filtration

Water utilities worldwide are turning to advanced filtration to meet increasingly stringent drinking water regulations that require the removal of pathogens, finer particulates, disinfection by-product precursors, and disinfectant tolerant micro-organisms from both groundwater and surface water supplies.

In the USA, the 1986 Safe Drinking Water Act (SDWA) and the 1998 Enhanced Surface Water Treatment Rule (ESWTR) focused on control of microbial contaminants, particularly Cryptosporidium oocyst, and Giardia cyst in systems using surface water, or ground water under the direct influence of surface water.

In the mid-1980’s, low pressure microfiltration membrane filtration (MF) was proven to meet and surpass the requirements of these rules through extensive pilot studies, challenge tests and the USEPA/NSF Environmental Technology Verification (ETV) Program. In the late-1990’s, awareness and interest in MF gained further momentum as researchers found reliable integrity test methods for MF membrane fibers and full scale projects using MF were implemented.

MF membranes are capable of removing particles with sizes down to 0.1 – 0.2 microns. A similar membrane called Ultrafiltration (UF) has a lower cutoff rating of 0.005 – 0.01 microns. MF and UF membrane systems generally use hollow fibers that can be operated in the outside-in or inside-out direction of flow. Pressure (5 to 35 psi) or vacuum (-3 to -12 psi for outside-in membranes only) can be used as the driving force across the membrane. Typical flux (the rate of finished water permeate per unit membrane surface area) at 20° C for MF and UF ranges from 50 to 100 gallons per square foot (GFD). MF and UF membranes are most commonly made from various organic polymers such as cellulose derivatives, polysulfones, polypropylene, and polyvinylidene fluoride (PVDF).

AMTA is the only industry organization that focuses specifically on membrane processes including reverse osmosis (RO), nanofiltration (NF), microfiltration (MF), ultrafiltration (UF), electrodialysis reversal desalination (EDR), and membrane bioreactors (MBR). The AMTA website offers a wide range of proprietary Fact Sheets and a complete Digital Library of presentations, posters, and papers on all topics related to membrane treatment, membrane systems, and regulatory and compliance topics.

AMTA is the only industry organization that focuses specifically on membrane processes including reverse osmosis (RO), nanofiltration (NF), microfiltration (MF), ultrafiltration (UF), electrodialysis reversal desalination (EDR), and membrane bioreactors (MBR). The AMTA website offers a wide range of proprietary Fact Sheets and a complete Digital Library of presentations, posters, and papers on all topics related to membrane treatment, membrane systems, and regulatory and compliance topics.

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Microfiltration Membrane Filtration