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Hollow Fiber Ultrafiltration Membrane Modules

Water resources continue to be one of the top environmental concerns around the world, leading to increased water recycling efforts in water and wastewater treatment facilities globally and reducing the consumption of fresh water. Getting wastewater to an acceptable level of purification for water reuse can be challenging as it requires several steps. On the other hand, it is important to have access to pure drinking water free from suspended solids and harmful pathogens. Ultrafiltration (UF) has shown demonstrated success in both applications.

UF is a process using a physical barrier to separate water and suspended solids, turbidity, silt, bacteria, and viruses from the feed water. In a system using pressurized PureULTRA II hollow fiber modules, the feed water may come from different sources such as surface water, groundwater, secondary or tertiary treated industrial wastewater, or other sources like tertiary treated municipal wastewater.

PureULTRA II UF modules are constructed using highly hydrophilic modified PVDF hollow fiber membrane with a tight nominal pore size of 0.025 micron. The outside-in flow configuration contributes to easier cleaning as it keeps the solids, pathogens, and other foulants on the outside of the fibers. The fiber is designed to handle most feed water sources and tolerate solids loadings while operating within an optimal flux range. These fibers offer 30% higher fiber tensile strength and elongation compared to state-of-the-art fibers on the market. They reject particulate matter, Giardia cysts, and Cryptosporidium oocysts, and can help in virus removal.


With PureULTRA II, most particles larger than 0.025 micron are rejected while much finer molecules (e.g., water and dissolved solids) pass through the tight pores of the hollow fiber membrane. Our unique permanently hydrophilic membrane is formed using PVDF polymer that is inert, to a great degree, to strong oxidants, allowing the hollow fiber to be cleaned aggressively during chemical cleaning cycles.

The membrane module design and hydraulics of PureULTRA II allow complete solids removal during drain cycles and therefore minimal fouling or chance of continual solids accumulation. These UF modules are designed to run at very low pressure (~0.02 Mpa / 3.0 psi) while operating at optimum fluxes. While the air diffuser installed in the modules leads to very high air penetration, the soft potting allows for fiber movement. Combining these features results in effective solids removal and minimal fiber breakage.


The expanded PureULTRA II portfolio increases the filtration area for the three module sizes to 60m², 80m² and 107m² respectively, resulting in a smaller overall footprint.

PureULTRA II modules can be operated at low pressures and optimum flux, leading to lower operating costs. The ability to clean the membrane and the overall module design leads to increased membrane life, lowering module replacement costs.


  • RO pretreatment
  • Surface water treatment (plant influent)
  • Water reuse
  • Tertiary wastewater treatment
  • Seawater treatment

Case Study

In this case study, a multi-tech system designed with PureULTRA II UF modules provides feed water to MICRODYN RO elements, demonstrating its effectiveness by:
  • Removing Total Suspended Particles (TSS),
  • significant reduction of Total Dissolved Solvents (TDS),
  • and chemical-free, high-purity feed water.

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