In this article discussed about basic concepts of Membrane filtration technology of Micron Filtration, Ultrafiltration, Nanofiltration and Reverse Osmosis
Micron Filtration | Ultrafiltration | Nanofiltration | Reverse Osmosis
What is membrane filtration
Membrane filtration is one of the efficient and economical way of separation components that are dissolved or suspended particles in a liquid.
Membrane filtration process is a physical separation method described by the facility to separate molecules by its characteristics and different sizes.
The membrane is a physical obstruction that depending on their physical and/or chemical properties, allows certain compounds to pass through membrane. So membrane filtration is a physical procedure for particle separation of particles by means of semi-permeable membranes.
Membranes commonly consist of a thin dense layer on top and porous support layer with that forms the actual membrane.
Membrane technology facilitates to boost product quality and at the same time bring down overall production costs.
Types of membrane filtration
Types of Membrane filtration based on the pore size of membrane and There are 4 types of technologies and they are described as below
Micron Filtration
Ultrafiltration
Nanofiltration
Reverse Osmosis
Membrane filtration is a dynamic filtering (cross-flow filtration) process. The flow direction of the material ( liquid or gas) is horizontally through membranes but not vertically through the filter area.
Advantages and Disadvantages of membrane filtration
1) High performance
2) Simple operation and compact units
3) It occupies less space other than conventional treatment schemes
4) Membranes filtration technology can be used to separate many kinds of contaminants
5) Disinfection can be performed without chemicals
6) Membranes have to be replaced on a regular basis due to its fouling
7) Production of polluted water from reject or back washing
Microfiltration
Microfiltration is a physical separation process that removes contaminants like microorganisms from process fluids, fats and suspended solids.
Generally, Microfiltration may use in combination with other membrane technologies such as ultrafiltration, reverse osmosis or nano-filtration.
The material of construction for micro filters surface depending on the application area means they may be made from plastic, textile fabric or stainless steel. Some new technology membranes are made robust materials and large area format to provide excellent economy and extremely stable performance independent of variability in feed water.
MF membranes are capable of removing particles of more than 0.1 micron sizes
Crossflow microfiltration (MF) is a highly efficient way to remove large colloids, micro-organisms and small suspended solids from large volumes of water.
Operating pressures are lower than compared with other types of membrane filters. Typically used 1 to 2 bar working pressure and backwash and air scrubbing techniques are used for this system to minimize requirements for chemical regeneration or replacements of membrance.
Application and advantages of Microfiltration
a) Reduces silt density index (SDI) to protect reverse osmosis or nano-filtration membranes and ion exchange.
b) Removes turbidity, suspended solids, bioburden
c) This technology is capable to remove chlorine and other chemicals which may be present in feed
d) Negligible waste stream
e) Microfiltration is a stable filtrate and low chemical compared to other types of membrane filters
f) Low operating cost
Ultrafiltration
Ultrafiltration is a low pressure, cross flow separation technique used to remove very fine particles, macromolecules, colloidal particles, proteins, microbiological contaminants, and large organic molecules from the feed stream.
Ultrafiltration membranes are capable of removing particles of 0.1 to 0.01 micron sizes. All smaller molecules and dissolved salts are pass through this type of membrane. The UF membrane rejects proteins, colloids, large organic molecules and microbiological contaminants.
Reverse osmosis membranes are very sensitive to silica, colloidal particular and organic matter fouling, which results higher operating cycles and frequent replacement of membrance. Ultra filtration is the best pretreatment technology for cost effective Reverse osmosis performance. Pretreatment with UF reduces fouling and increase the life of the RO membrance.
The Ultrafiltration system works at 90% recovery. This means that 90% of the feed material will be available as permeate and the remaining 10% will carry all the rejected material that would be drained.
Applications, benefits and disadvantage include
a) The common applications of UF technology for pyrogen control in both low and high temperature distribution using both hollow fiber, pharmaceutical water processing are in pretreatment and ceramic technologies.
b) Ultrafiltration is used for such applications as metal recovery and wastewater cleaning in the field of metallurgy, separating proteins and cold sterilization in the pharmacy
c) UF system will retain particles, bacteria, viruses, pyrogens (endotoxins), colloids and large organic molecules.
d) Excellent protection for RO system when used in prefiltration treatment
e) Dissolved salts and smaller organic molecules pass freely through this ultrafiltration membranes system.
Nanofiltration (NF)
Nanofiltration is a specialty membrane process which rejects particles in the approximate size range of 0.001 micron means one nanometer, hence this membrane is termed as &#;nanofiltration.&#; Nanofiltration is a pressure-driven membrane processes.
Nanofiltration liquid separation technology operates in the realm between Ultrafiltration and reverse osmosis. It means this membrane is positioned between reverse and ultrafiltration.
When compare to reverse osmosis, nanofiltration uses lower pressures and filters with larger pore sizes. The particle size, which is retained in NF, is the size of single and divalent heavy metal ions.
Nanofilters are commonly referred to as membrane softeners because they will commonly reject the double-positively charged (i.e., calcium & magnesium) hardness ions fairly well but cannot reject the single-positive charged soft ions like sodium & potassium. Some type of NF membranes removal of monovalent ions varies between 50% to 90% depending on the material which is used for the membrane.
Nanofiltration membranes and systems are used for food & pharmaceutical and water softening applications.
You will get efficient and thoughtful service from ZHUAN LV.
Reverse Osmosis
Reverse osmosis (RO) is the finest level of membrane filtration technology to separation in liquids. The RO membranes system used an efficient separation of all dissolved salts and inorganic molecules as well as most organic compounds
Reverse Osmosis membranes are capable to separation of particles 0.001 micron (100 Daltons) sizes.
In the design and staging of Reverse Osmosis systems in single or multipass arrangements for low fouling performance, for extremely high recovery rates and stable system without the use of chemicals.
Advantages of RO system
a) RO system is a compact and modular design
b) No added chemicals
c) Maximum efficiency in throughput
d) We can get high recovery rates of 95%
e) Very high rejection rates producing high purity filtrate
Please go through the below link for more information regards Reverse Osmosis system
Levels of membrane separation
S.No
Type of membrane
Size of Particle
Typical Operating Pressure in Bar
Type of Particle
1
Microfiltration
> 0.1 micron
< 2
Large colloids, micro-organisms and suspended particles,
2
Ultra filtration
0.1 to 0.01 micron
1 to 10
Proteins, colloids, large organic molecules and microbiological contaminants &#; Macro molecules,
3
Nan filtration
0.01 to 0.001 micron
5 to 35
Double-positively charged (i.e., calcium & magnesium) hardness ions. Micro molecular organic compounds
4
Reverse Osmosis
< 0.001 µm
15 to 150
Dissolved salts and inorganic molecules
Related Articles
Mills and Diffusers Technology in Juice extraction systems of sugar industry
ETP | Sugar industry effluent treatment plant process philosophies
Activated Sludge Process for Wastewater Treatment | Anaerobic Digestion
Anaerobic Treatment Process for Industrial Waste Water | Anaerobic digester
CSTR Digester | Anaerobic Treatment for Raw Spent wash in Distillery
Pump Power Calculation Formula | Specific speed of a centrifugal pump
The membrane filter is widely used in today&#;s life, including ultrafiltration membrane, microporous membrane, nanofiltration membrane, microfiltration membrane, mesopore fiber ultrafiltration membrane, etc.
Known as surface filtration, membrane filtration is a process that the solid particles can be separated through a very thin filter medium. The particles are usually larger than the pore size of the membrane.
During separation, a semi-permeable membrane acts as a selective barrier retaining the particles bigger than the pore size, as the smaller molecules go through the pores. Removing all micro-organisms and particles reliably, without any effects on the ingredients during the whole process.
In terms of shape, filter membranes are usually divided into two types: disc membranes and roll membranes.
Hawach can supply a variety of raw materials for different materials to meet and adapt to the differentiated needs of production membrane manufacturers. The rolling membrane is rectangularly rolled together and is indicated by the width, with 254mm, 260mm, 270mm, 280mm, and 310 mm available. The inner core is 22mm.
The disc membrane filter that HAWACH can provide diameter is 13mm to 293mm, the hole diameter is 0.1μm to 10μm, etc., and other specifications of the membrane can be customized according to the needs of users.
Filter membrane materials include nylon, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), mixed cellulose (MCE), cellulose acetate (CA), glass fiber (GF), Polypropylene (PP), polyethersulfone (PES).
Its application includes HPLC sample preparation, routine QC analysis, protein deposit movement, dissolution test, food analysis, biofuel analysis, and environmental test. We choose some of them for a detailed introduction. For all membrane features and performance, please contact Hawach directly(: or : +86-29-).
The membrane filter is used for food, beverage, medical medicine, municipal water treatment, industrial high pure water, boiler water, seawater desalination, electronic industry ultra-pure water, wastewater treatment and reuse, material concentration and purification, and other industries.
The PP filter membrane has acid and alkali resistance, abrasion resistance, impact resistance, uniform micropore distribution, large filtration area, and good water permeability. Widely used in injection cleaning, medicinal liquid, medicinal wine, oral liquid, beverage, daily water, wastewater, air filtration, etc.
Due to the fiber material of the glass fiber membrane, it is not easy to clog, so it can provide excellent prefiltration functions for a series of filtration workflows. From basic liquid filtration to highly specialized gas and air filtration, it&#;s all covered. These properties also make it excellent as a direct filter for a buffer, reagent, and protein solution clarification, as well as for gravimetric analysis, air monitoring, and wastewater analysis. The 100% borosilicate structure of the glass fiber membrane not only gives it a pure white appearance but compared with standard cellulose membranes, even with continuous use, there will be no performance degradation due to increased filtration load.
Cellulose acetate(CA) filter membrane is mainly used for daily air pollution monitoring and special monitoring of solid pollutants, microorganisms, oil and acid mist in the air, efficient collection of fine particles, and water pollution analysis. It is an ideal product for collecting smoke and dust in the air and measuring it accurately. And it is used for the pre-filtration of the membrane to prevent the clogging of the membrane. Large surface area uses glass fiber membranes for excellent retention.
In addition to the wide range of applications in the pharmaceutical and biotechnology industries, PES membranes filter are also suitable for other fields such as medical, food and beverage and drinking water, microelectronics, fine chemicals, etc.
The nylon filter membrane material is aliphatic nylon, which has good hydrophilicity and resistance to acid and alkali of the appropriate concentration. It is not only suitable for aqueous solutions containing acid and alkali, but also for organic solvents, such as alcohols, hydrocarbons, ethers, esters, ketones, homologs of benzene and benzene, dimethyl formamide, dimethyl sulfoxide, etc., are one of the most widely applicable microporous membranes. (Belonging to the terminal filter membrane).
For the PVDF filter, as the pore size of the membrane continues to decrease, the membrane binds to low molecular weight proteins more firmly. The use of the PVDF membrane requires pretreatment. The purpose of treatment with methanol is to activate the positively charged groups on the membrane and make it easier to bind to negatively charged proteins.
NC membranes are used in Northern Blot, Southern Blot, and Western Blot. Hybridization techniques are divided into solid phase hybridization and liquid phase hybridization. The solid-phase hybridization technology is currently more commonly used. The nucleic acid to be tested is first bound to certain solid-phase support, and then hybridized with the labeled probe in the liquid phase. The solid support is usually the nitrocellulose membrane.
The MCE filter membrane has relatively uniform pore size, high porosity, no media shedding, thin texture, low resistance, fast filtration speed, minimal adsorption, and low cost, but it is not resistant to strong acid & alkali solutions and organic solutions.
The PTFE filter membrane is made of PTFE, through a special process, two-way stretching, using the unique node fibril properties of the PTFE film, smooth surface, chemical resistance, air and water impermeability, large air permeability, flame retardant, high temperature resistance. The product is resistant to strong acids and alkali, non-toxic, etc., with high filtration efficiency, up to 99.99%, near zero emission; low running resistance, fast filtration speed; long service life, and reusable, thereby reducing operating costs.
Hydrophilic PTFE filter membrane has wide applications, like the flue gas filtration of various industrial furnaces, for instance, the chemical industry, metallurgy, power generation, cement, etc.
Hawach filter membranes have two types: round disc membrane filters and roll type ones. They can be used for filtration and sterilization of liquids, gas, and other samples.
Contact us to discuss your requirements of membrane pleated filter. Our experienced sales team can help you identify the options that best suit your needs.