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Filtration Solutions


RO  Pretreatment 


A common requirement for the influent of RO surface water filtration is to have a 15-minute silt density index value (SDI 15 from ASTM D4189-07) of less than 3.0.  With a conventional cartridge filter, this requirement is not likely to be met. This is especially true when processing highly challenging water. The figure on the right shows the SDI of typical filtrate from a 1-micron cartridge filter processing feed water with an SDI of 6.7.


The Coiled Membrane Filter (CMF) from FSI is ideal for the RO pretreatment application. It can remove submicron solids in many water and wastewater treatment processes to provide a sustainable high-quality feed to improve RO system Reliability, Availability and Maintainability (RAM). CMF is the most cost-effective filtration system for removing high concentrations of submicron solids from water (up to 5% by weight) for industrial and municipal applications. For service with highly challenging surface water (SDI 15 = 6.7), the system can provide an effluent with 

SDI 15 < 2 and Turbidity <1.0 with no additives (i.e. coagulants).

The unique Dean Flow technology of the CMF system creates a self-cleaning mechanism resulting in an enhanced flux rate, longer membrane service life, and reduced energy footprint. With the high-quality output and minimum life cycle cost, CMF addresses the highest cost components of membrane Desalination and Wastewater Treatment, which are


1. Flux reduction and fouling of primary RO membrane downstream 

2. Production loss and higher O&M budgets due to necessary maintenance

3. CIP and downtime with conventional pretreatments including multi-              media and MF/UF filters

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