Ultrafiltration
Encyclopedia
Ultrafiltration is a variety of membrane filtration
in which hydrostatic pressure forces a liquid against a semipermeable membrane
. Suspended solids
and solute
s 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.
Consists of large consecutive layers of membrane and support material rolled up around a tube.
Maximizes surface area.
Less expensive, however, more sensitive to pollution.
Tubular membrane:
The feed solution flows through the membrane core and the permeate is collected in the tubular housing.
Generally used for viscous or bad quality fluids.
System is not very compact and has a high cost per m2 installed
Hollow fiber membrane:
The modules contain several small (0.6 to 2 mm diameter) tubes or fibers.
The feed solution flows through the open cores of the fibers and the permeate is collected in the cartridge area surrounding the fibers.
The filtration can be carried out either “inside-out” or “outside-in”
TMP (transmembrane pressure) is generated in the feed by a pump, while the permeate stays at atmospheric pressure.
Pressure-vessels are generally standardized, allowing the design of membrane systems to proceed independently of the characteristics of specific membrane elements.
Immersed system:
Membranes are suspended in basins containing the feed and open to the atmosphere.
Pressure on the influent side is limited to the pressure provided by the feed column.
TMP is generated by a pump that develops suction on the permeate side.
Ultrafiltration, like other filtration methods can be run as a continuous or batch process
Membrane technology
The membrane technology covers all process engineering measures for the transport of substances between two fractions with the help of permeable membranes...
in which hydrostatic pressure forces a liquid against a semipermeable membrane
Semipermeable membrane
A semipermeable membrane, also termed a selectively permeable membrane, a partially permeable membrane or a differentially permeable membrane, is a membrane that will allow certain molecules or ions to pass through it by diffusion and occasionally specialized "facilitated diffusion".The rate of...
. Suspended solids
Suspended solids
Suspended solids refers to small solid particles which remain in suspension in water as a colloid or due to the motion of the water. It is used as one indicator of water quality....
and solute
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
s of high molecular weight are retained, while water and low molecular weight solutes pass through the membrane. This separation process
Separation process
In chemistry and chemical engineering, a separation process, or simply a separation, is any mass transfer process used to convert a mixture of substances into two or more distinct product mixtures, at least one of which is enriched in one or more of the mixture's constituents. In some cases, a...
is used in industry and research for purifying and concentrating macromolecular (103 - 106 Da
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
) solutions, especially protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
solutions. Ultrafiltration is not fundamentally different from microfiltration
Microfiltration
Microfiltration is a membrane technical filtration process which removes contaminants from a fluid by passage through a microporous membrane. A typical microfiltration membrane pore size range is 0.1 to 10 micrometres...
, nanofiltration
Nanofiltration
Nanofiltration is a relatively recent membrane filtration process used most often with low total dissolved solids water such as surface water and fresh groundwater, with the purpose of softening and removal of disinfection by-product precursors such as natural organic matter and synthetic organic...
or gas separation
Gas separation
Gas mixtures can be effectively separated by synthetic membranes. For other methods see adsorption, absorption, cryogenic distillation.Membranes are employed in:* separation of nitrogen or oxygen out of air...
, 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.
Process
Ultrafiltration systems eliminate the need for clarifiers and multimedia filters for waste streams to meet critical discharge criteria or to be further processed by wastewater recovery systems for water recovery. Efficient ultrafiltration systems utilize membranes which can be submerged, back-flushable, air scoured, spiral wound UF/MF membrane that offers superior performance for the clarification of wastewater and process water.Membrane geometries
Spiral wound module:Consists of large consecutive layers of membrane and support material rolled up around a tube.
Maximizes surface area.
Less expensive, however, more sensitive to pollution.
Tubular membrane:
The feed solution flows through the membrane core and the permeate is collected in the tubular housing.
Generally used for viscous or bad quality fluids.
System is not very compact and has a high cost per m2 installed
Hollow fiber membrane:
The modules contain several small (0.6 to 2 mm diameter) tubes or fibers.
The feed solution flows through the open cores of the fibers and the permeate is collected in the cartridge area surrounding the fibers.
The filtration can be carried out either “inside-out” or “outside-in”
Ultrafiltration module configurations
Pressurized system or pressure-vessel configuration:TMP (transmembrane pressure) is generated in the feed by a pump, while the permeate stays at atmospheric pressure.
Pressure-vessels are generally standardized, allowing the design of membrane systems to proceed independently of the characteristics of specific membrane elements.
Immersed system:
Membranes are suspended in basins containing the feed and open to the atmosphere.
Pressure on the influent side is limited to the pressure provided by the feed column.
TMP is generated by a pump that develops suction on the permeate side.
Ultrafiltration, like other filtration methods can be run as a continuous or batch process
Applications
- DialysisDialysisIn medicine, dialysis is a process for removing waste and excess water from the blood, and is primarily used to provide an artificial replacement for lost kidney function in people with renal failure...
and other bloodBloodBlood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
treatments - Concentration of milkMilkMilk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...
before making cheeseCheeseCheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms.... - Fractionation of proteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s - Clarification of fruit juice
- Recovery of vaccineVaccineA vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
s and antibioticAntibioticAn antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s from fermentationIndustrial fermentationIndustrial fermentation is the intentional use of fermentation by microorganisms such as bacteria and fungi to make products useful to humans. Fermented products have applications as food as well as in general industry.- Food fermentation :...
broth - Laboratory grade water purificationWater purificationWater purification is the process of removing undesirable chemicals, materials, and biological contaminants from contaminated water. The goal is to produce water fit for a specific purpose...
- Wastewater treatmentWastewater TreatmentWastewater treatment may refer to:* Sewage treatment* Industrial wastewater treatment...
- Drinking waterDrinking waterDrinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
disinfectionDisinfectionDisinfectants are substances that are applied to non-living objects to destroy microorganisms that are living on the objects. Disinfection does not necessarily kill all microorganisms, especially nonresistant bacterial spores; it is less effective than sterilisation, which is an extreme physical...
(including removal of virusVirusA virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es) - Removal of endocrines and pesticidePesticidePesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s combined with Suspended Activated CarbonActivated carbonActivated carbon, also called activated charcoal, activated coal or carbo activatus, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions.The word activated in the name is sometimes replaced...
pretreatment
External links
- www.kontekecology.com- Kontek Ecology Systems Inc. Specialist in wastewater treatment
- www.microfiltusa.com- MicrofiltUSA Sales and Service Inc. Specialist in Housings for Ultrafiltration
- www.jdiinc.com- JDI, Inc. INFINITEX Ultrafiltration (U/F) Systems