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Understanding Cross Flow Filtration 

Cross flow filtration – a filtration process in which feed water flows tangentially across a membrane surface – is widely utilized in wastewater filtration. The turbulence created across the membrane surface provides optimal flux performance and prolongs filter functionally. 

Cross filtration works by introducing feed water under pressure across the membrane surface, instead of directly onto the filter. During filtration, any material smaller than the cross flow membrane pore passes through the membrane, while larger suspended particulates remain in the retentate stream. 

Cross Flow Filtration and Dead-End Filtration  

There are two major competing types of filtration technologies used in industrial processes: dead-end filtration vs cross flow filtration. In dead-end filtration, the solids collect on the surface of the filter media as a stable filter cake that grows in thickness and increases flow resistance. The filter media is usually a consumable component disposed of with the filtered solids.

In the cross flow filtration process, the concentrate feed water flows across the surface of a membrane filter media with minimal solids buildup and at constant low flow resistance. The membrane is not a consumable component. The differences in these two filtration processes are displayed in the graphic below.

Microfiltration and Cross flow Filtration 

Microfiltration is a separation process utilized to remove particles typically in the 0.1 to 10 micron range. Cross flow filtration can be utilized to achieve microfiltration and can be an ideal solution for processing in many industrial wastewater applications. Not only does cross flow result in higher quality and larger volumes of permeate, but cross flow can be used together with reverse osmosis (RO) systems to build energy efficient zero liquid discharge systems. By incorporating POREX® Filtration’s microfiltration membranes, system integrators can design filtration systems that achieve long-term reliability, maintainability, and ease of operation across many challenging applications.  

Porex and Cross Flow Filtration

Porex TMF™ products are available in 0.02, 0.05, and 0.1 micron pore sizes, which can be utilized as microfiltration and ultrafiltration membranes. Each membrane provides optimal cross flow filtration for a variety of applications, including RO reject recycling, metals finishing, semiconductor processes and fluoride reduction. For consistent, reliable cross flow filtration, Porex TMF membranes provide long operating life with ease of service and excellent filtration.  



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