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Ultrafiltration and Reverse Osmosis

Paper Type: Free Essay Subject: Biology
Wordcount: 1462 words Published: 29th May 2018

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Ultrafiltration is a variety of membrane filtration in which hydrostatic pressure forces a liquid against a semipermeable membrane. 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 microfiltration, nanofiltration or gas separation, except in terms of the size of the molecules it retains. Ultrafiltration is applied in cross-flow or dead-end mode and separation in Ultrafiltration undergoes concentration polarization.

The main deference between Ultrafiltration and Reverse Osmosis is that the Ultrafiltration membranes have larger pore size than the Reverse Osmosis ranging from 1 -100 nm.

Ultra-Filtration System (UF) is a modern process technology to purify water for a wide range of applications, including semiconductors, fisheries, food processing, biotechnology, pharmaceuticals, power generation, seawater desalting, and municipal drinking water.

Ultra-Filtration System is the cost effective water purification system it is an immediate source of pure water. The process of Ultra-Filtration System (UF) represents the finest level of liquid filtration available today. And though the term sounds mysterious, Ultra-Filtration System isn’t really that complicated.

Ordinary water filters use a screen to separate particles from water streams. The holes that these Filters have are fairly large. This allows just about everything that is dissolved in the water to pass through as well. An Ultra-Filtration System employs a semi-permeable membrane. The membrane is a thin, multi-layered sheet with pores so small that water molecules can pass through, but it acts as a barrier to dissolved solids like salts and other chemicals. Thus even Bacteria and viruses are trapped and not allowed to pass through.

Maximum purity is attained by reducing 99% of the organics (including pyrogens) and bacteria

Ultra-Filtration Systems remove salts, micro-organisms and high molecular weight organics. The System capacity depends on three major factors.

The feed water temperature

Total Dissolved Solids in feed water ( TDS )

Operating pressure and the over all recovery of the system.

For waters with Total Dissolved Solids of 700 ppm or more, Ultra-Filtration System is less expensive than Ion Exchange. Even on comparable water it has better sediment and organic removal capabilities. Compared with Distillation, Ultra-Filtration System uses only a fraction of the total energy and does not have high temperature problems, scaling and corrosion.

Compared with other conventional water treatment processes, Ultra-Filtration System has proven to be the most efficient means of removing salts, chemical contaminants and heavy metals, such as lead, from drinking water.

A simple illustration to show how Ultra-Filtration System works to purify water is provided.

Ultra-Filtration System is a membrane separation process in which feed water flows along the membrane surface under pressure. Purified water permeates the membrane and is collected, while the concentrated water, containing dissolved and undissolved material that does not flow through the membrane, is discharged to the drain.


With cross-flow filtration, the feed stream continuously flows across the membrane; anything that does not go through the membrane gets carried off with the cross-flow and is sent to the reject port. In this way the “Reverse Osmosis” process can continue non-stop without clogging the membrane.

Ultra-Filtration System can treat a wide variety of health and aesthetic contaminants that cause unpleasant taste, color, and odor problems like a salty or soda taste caused by chlorides or sulfates. Ultra-Filtration System can also be effective for treating health contaminants like arsenic, herbicides/pesticides, lead, mercury, nitrate, and radium.

Detailed Product Description

Ultra-filtration Water Purifier System

Ultra-filtration Water Purifier System

100% SUS 304 Stainless Steel Body

UF membrane pore size 0.01 micron

Ultra-filtration Water Purifier System

100% SUS 304 Stainless Steel Body

UF membrane pore size 0.01 micron

Max Water Flow : 2,500 Liters / Hour

Constructed with 3800 – 4000 pcs of high quality Seven Multi-hole PVC UF Alloy Membrane.

99.99% bacteria & virus free

Preserve mineral

Turbidity 0.1 NTU.

Micro filtration and ultra filtration

Membrane technology

The principle of micro filtration and ultra filtration is physical separation. The extent to which dissolved solids, turbidity and microorganisms are removed is determined by the size of the pores in the membranes. Substances that are larger than the pores in the membranes are fully removed. Substances that are smaller than the pores of the membranes are partially removed, depending on the construction of a refuse layer on the membrane.

Micro filtration and ultra filtration are pressure-dependent processes, which remove dissolved solids and other substances from water to a lesser extent than nano filtration and Reverse Osmosis.

Micro filtration

Membranes with a pore size of 0.1 – 10 µm perform micro filtration. Microfiltration membranes remove all bacteria. Only part of the viral contamination is caught up in the process, even though viruses are smaller than the pores of a micro filtration membrane. This is because viruses can attach themselves to bacterial biofilm.

Micro filtration can be implemented in many different water treatment processes when particles with a diameter greater than 0.1 mm need to be removed from a liquid.

Examples of micro filtration applications are:

  • Cold sterilization of beverages and pharmaceuticals
  • Clearing of fruit juice, wines and beer
  • Separation of bacteria from water (biological wastewater treatment)
  • Effluent treatment
  • Separation of oil/ water emulsions
  • Pre-treatment of water for nano filtration or Reverse Osmosis
  • Solid-liquid separation for pharmacies or food industries

Ultra filtration

For complete removal of viruses, ultra filtration is required. The pores of ultra filtration membranes can remove particles of 0.001 – 0.1 µm from fluids.

Examples of fields where ultra filtration is applied are:

  • The dairy industry (milk, cheese)
  • The food industry (proteins)
  • The metal industry (oil/ water emulsions separation, paint treatment)
  • The textile industry

Protection of membranes

Ultra filtration can also be applied for pre-treatment of water for nano filtration or Reverse Osmosis.

Pre-treatment of water is very important when these filtration techniques are applied, because membrane fouling can easily disturb the purification process. Pre-treatment is not only important for nano filtration and Reverse Osmosis processes, but also for the above-mentioned microfiltration and ultra filtration processes. Pre-treatment needs to be determined as soon as the composition of the wastewater is known.

To prevent plugging or damaging of membranes by hard and sharp particles from the feed water, water needs to be pre-filtered before micro filtration or ultra filtration processes take place. The pores of the pre-filtration unit need to be between 0.5 and 1.0 mm, depending on the composition of the wastewater. Further pre-treatment will not be necessary when micro filtration or ultra filtration is performed.

Further treatment

When wastewater is treated it needs to answer certain demands. It depends on these demands whether or not permeates need additional treatment after microfiltration or Ultrafiltration.

Purification techniques that are eligible for additional treatment are:

  • Disinfection techniques
  • Quick filtration
  • Active carbon filtration

Nano filtration and Reverse Osmosis (RO)






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