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About Ultrafiltration (UF)

 

UF Water Purifier in Bangladesh is widely using now a days and UF Water Purifier is most common and Popular Water Purification Technology in Bangladesh also, Ultrafiltration (UF) is a variety of membrane filtration in which forces like pressure or concentration gradients lead to a separation through a semipermeable membrane. Suspended solids and solutes of high molecular weight are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in the permeate. This separation process is used in industry and research for purifying and concentrating macromolecular (103 – 106 Da) solutions, especially protein solutions. Ultrafiltration is not fundamentally different from microfiltration. Both of these separate based on size exclusion or particle capture. It is fundamentally different from membrane gas separation, which separate based on different amounts of absorption and different rates of diffusion. Ultrafiltration membranes are defined by the molecular weight cut-off (MWCO) of the membrane used. Ultrafiltration is applied in cross-flow or dead-end mode.

How ultrafiltration (UF) systems work ?

Ultrafiltration uses hydrostatic pressure to force water through a semi-permeable membrane. The pore size is usually 103-106 Daltons. Ultrafiltration may use spiral wound membranes that utilize cross-flow separation, hollow fiber membranes, or from the outside-in using a vacuum to purify water. The membranes remove very small particles such as chlorine-resistant organisms, bacteria, organics, sediment, high molecular weight solutes and other suspended solids. 

Ultrafiltration is a membrane filtration process that is removes suspended solids, bacteria, viruses, endotoxins and more to produce high purity water with low silt density. Ultrafiltration membranes are tighter than microfiltration but looser than nanofilters and reverse osmosis. Lower pressure is used to force fluid through the membrane which results in lower operating costs. Also, it is very effective at removing tiny particles which can quickly foul reverse osmosis membranes and therefore used as pretreatment upstream of RO.

What is Ultrafiltration (UF) in terms of Membrane Filter Technology?

Ultrafiltration (UF) is a type of membrane filtration in which hydrostatic pressure forces a liquid against a semipermeable membrane. A semipermeable membrane is a thin layer of material capable of separating substances when a driving force is applied across the membrane. Once considered a viable technology only for desalination, membrane processes are increasingly employed for removal of bacteria and other microorganisms, particulate material, and natural organic material, which can impart color, tastes, and odors to the water and react with disinfectants to form disinfection byproducts (DBP). As advancements are made in membrane production and module design, capital and operating costs continue to decline.

filter technologyUltrafiltration uses hollow fibers of membrane material and the feed water flows either inside the shell, or in the lumen of the fibers. Suspended solids and solutes of high molecular weight are retained, while water and low molecular weight solutes pass through the membrane. This separation process is used in industry and research for purifying and concentrating macromolecular (103 – 106 Da) solutions, especially protein solutions. Ultrafiltration is not fundamentally different from reverse osmosis, microfiltration or nanofiltration, except in terms of the size of the molecules it retains. When strategically combined with other purification technologies in a complete water system, UF is ideal for the removal of colloids, proteins, bacteria, pyrogens, proteins, and macromolecules larger than the membrane pore size from water. The primary removal mechanism is size exclusion, though surface chemistry of the particles or the membrane may affect the purification efficiency. UF can be used as pretreatment for reverse osmosis systems or as a final filtration stage for deionized water.

The primary advantages of low-pressure UF membrane processes compared with conventional clarification and disinfection (post chlorination) processes are:

  • No need for chemicals (coagulants, flocculates, disinfectants, pH adjustment);
  • Size-exclusion filtration as opposed to media depth filtration;
  • Good and constant quality of the treated water in terms of particle and microbial removal;
  • Process and plant compactness; and
  • Simple automation.

Features of Ultrafiltration (UF)

  • High solids tolerance is capable of handling high turbidity spikes and coagulant doses
  • Lower chemical usage over comparable systems
  • Ability to retrofit other ultrafiltration (UF) and microfiltration (MF) systems
  • Simple, automated operation
  • Packaged and custom designs for greenfield or retrofit solutions
  • Produce high-quality feed water to enable Reverse Osmosis systems to operate at peak performance with reduced fouling and less cleaning
  • Enhance treated effluent quality from secondary wastewater treatment process

Principles of Ultrafiltration

Ultrafiltration (UF) is an important water purification technology used for production of high-purity water. UF is effective in the removal of colloids, proteins, bacteria, pyrogens (e.g. gram-negative bacterial endotoxins), and other organic molecules larger than 0.1 – 0.2 Micron in size. How Ultrafiltration membranes work

Basic Principles of Ultrafiltration

Ultrafiltration is a pressure-driven purification process in which water and low molecular weight substances permeate a membrane while particles, colloids, and macromolecules are filtered. The primary removal mechanism is size exclusion. A properly designed UF cartridge allows efficient rising of ionic redidue from the cleaning and rapidly returns to optimal resistivity and organic purity (see figures 1 and 2). Reagent-grade sodium hydroxide has proven to be and effective cleaning agent with the following benefits:

  • Effective bacterial destruction
  • Effective depyrogenation (endotoxin reduction)
  • Efficient destruction of organic contamination
  • Reduced occurrence of chemical by-product formation
  • Minimal residue of chemical interference
  • Economical and easy-to-use cleaning age

Ultrafiltration membrane sanitation tables

The Unique Features of Ultrafiltration Module

Altough there are many products on the markets using hollow fibre membranes this particular product is unique in that it has a build in mesh filter or activated carbon filter to protect the membrane itself and that it has a build back flush functionality. In combination with low minimum working pressure requirement of only 2 bar this filter is ideal in decentralised and renewable powered applications.

Minimum working pressure: 2.0 bar (30psi)
Maximum working pressure: 6.9 bar (100psi)
Maximum water temperature: 38°C
Minimum water temperature: 0°C