Ultrafiltration is used for the separation of suspended solids, colloids, bacteria and virus. This technique uses membranes with pore size between 1-100nm.

As the difficulty has been arising in continous removal of tiny particles using conventional watertreatment, and increased concerns about chlorine-resistant organisms, ultrafiltration is gaining popularity and becoming the preferred method of choice for municipal water treatment plants.

Ultrafiltration is very effective at removing very small particles which can quickly foul reverse osmosis membranes, and then resulting in reducing the silt density index of the water. For this reason, it frequently serves as pre-treatment for surface water, seawater, and biologically treated municipal water upstream of RO.

In ultrafiltration, thewater flow is directed through a membrane in a cross flow direction, and a portion of input water flows across the surface of the membrane at a precise rate of flow and pressure. This allows most contaminant stuffs to be removed, but also allows the membrane surface to stay clean, and eliminating the fouling that can leave other systems ineffective until manual cleaning occurs.

UF is particularly meant and effective for discarding the colloid (emulsion). It is an effective pre-treatment to Reverse Osmosis used in desalination.It can also be used as a pre-treatment for water that will go through a reverse osmosis system. Water that has been through the ultra-filtration process can also be used as drinkable water in hotels, resorts, recreational centres and the like.

The following applications use the contaminant-free water resulting from the ultra-filtration process: These include -

• Private Water Supplies

• Engineering Activities

• Bood Processing

• Brewing and Distillery, etc

Ultrafiltration process removes the highest sensitivity of conventional plant treatment steps of coagulation, sedimentation and filtration to variable influent turbidity and particle charges.UF is also taken into useby industries to separate suspended solids from solution. Industrial applications include power generation, food and beverage processing, pharmaceutical production, biotechnology, and semiconductor manufacturing. Examples of industrial applications include:

• Washwaters – Tramp Oils, Alkaline & Acidic Washwaters

• Stamping - Heavily Fortified Stamping Fluids & Washwaters

• Transportation - Oily Water from Vehicle Discharge

• Machining and Grinding - Water Soluble and Synthetic Coolants

• Die Casting - Mould Release Fluids & Washwaters

• Vibratory Deburring - Oil and Solid Laden Deburring Liquids

• Primary Metals - Rolling & Drawing Fluid, Coolants

Empty/hollow fibres of membrane material is used in ultrafiltration and the feed water flows either inside the shell, or in the lumen of the fibres. What is retained is the suspended solids and particles of high molecular weight, on the other hand, water and low molecular weight solutes pass through the membrane. Ultrafiltration is somewhat similar to reverse osmosis, microfiltration or nanofiltration, except in terms of the molecule size it retains. When comparing and strategically combining 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.