Nano NF filtration technology is a liquid filtration technology using a membrane filter based on some features of RO reverse osmosis technology. Water filtration efficiency is based on the difference between the pore size on the filter membrane. Unlike RO with high ability to remove almost all dissolved substances, NF nanofiltration has ionic filtration, so it can soften water by removing high valence ions, such as calcium, magnesium but little removal of low valence ions, such as chloride.
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What is Nanofiltration (Nanofiltration)?
NF has intermediate characteristics between UF ultrafiltration and RO . reverse osmosis filtration
Nanofiltration technology is the process in which water is passed through a membrane filter to remove dissolved substances with a size between 1-10 nanometers through microscopic holes in the membrane. Hence we have the term "nanofiltration", that is, filtering substances with a nano-size.
Comparison of filtration capacity based on solute size and weight:
RO (Reverse Osmosis) > NF (Nanofiltration) > UF (Ultrafiltration).
Nanofiltration NF can remove organic molecules with molecular weight greater than 200-400. Nanofiltration membrane can effectively remove a number of contaminants such as:
Dissolved organic matter
Endotoxins/pyrogens
Pesticides
Herbicide
Antibiotic
Nitrates
Street
Emulsions, colloids
Metal ions
NF nanofiltration also removes about 20-98% of some dissolved salts. Specifically, 20-80% for salts with divalent anions (such as Sodium Chloride or Calcium Chloride) and 90-98% for salts with divalent anions (such as Magnesium Sulfate). The transmembrane pressure is typically 50-225 psi (3.5-16 bar).
The ideal nanofiltration membrane has a very high permeability, but the ideal permeability of solutes can be close to zero or some higher value, depending on the solute and application. For example, an application may require near-zero permeability for pesticides and 50% permeability for calcium ions. domestic water purifier machine price in bangladesh
Typical applications of nanofiltration membrane systems:
Removal of color and total organic carbon (TOC) from surface water.
Remove hardness or radium from well water.
Reduce total dissolved solids (TDS).
Separation of organic matter from inorganic matter in a number of fields such as food, wastewater treatment applications.
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Learn about NF (Nanofiltration Technology)
Pressure and cross flow
Like reverse osmosis membranes, nanofiltration membranes used in separation systems use applied pressure to effectively overcome the osmotic pressure of the system, reversing the flow of solvents through a magnetic semi-permeable membrane. region of higher solute concentration to an area of lower concentration.
This "reversed" flow, and the degree of permeability of the Nano membrane, does not allow too large solutes to pass through the membrane, but rather traps it on the higher concentration side of the membrane. Whereas pure water contains the desired/allowed solutes to flow through.
Nanofiltration membranes are similar to RO membranes in another way: They use a cross-flow configuration. Cross-flow helps to minimize clogging, or the accumulation on the membrane of solutes that cannot pass through the semi-permeable membrane. In simple terms, in a pressurized feedwater cross-flow forcing water of lower concentration through the NF membrane, while a more concentrated stream of water moves across the membrane surface, carrying the removed salts and other impurities. Pure water is called osmotic water, while water with a higher concentration is called concentrated or wastewater.
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NF . nanofiltration membrane performance
Influential factors
The main performance parameters of nanofiltration membranes are the permeability flux and salt removal. Under specific reference conditions, these intrinsic properties are predictable. The permeability flux and rejection of a membrane system are influenced mainly by variable parameters, including:
Pressure: With increasing flow pressure, the amount of permeable dissolved solids will decrease while the seepage flux will increase.
Temperature: If the temperature is increased while all other parameters (pressure, recovery and salt concentration in the feed water) remain constant, the seepage flux and salt content will increase.
Recovery: Recovery is the ratio of seepage flow to feedwater flow. In the case of increased recovery, the seepage flux will decrease and stop if the salt concentration reaches a value where the osmotic pressure of the concentrate is as high as the feed water pressure. Salt removal will decrease with increasing recovery.
Salt concentration in feed water: With increasing salt concentration in feed water, seepage flux will decrease while salt content will increase.
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