Nanofiltration is a relatively recent membrane process used most often with low total dissolved solids water such as surface water and fresh groundwater, with the purpose of softening (polyvalent cation removal) and removal of disinfection by-product precursors such as natural organic matter and synthetic organic matter [1] [2].
Nanofiltration is also becoming more widely used in food processing applications such as dairy for simultaneous concentration and partial (monovalent ion) demineralisation.
In much of the developing world, clean drinking water is hard to come by, and nanotechnology provides one solution. While nanofiltration is used for the removal of other substances from a water source, it is also commonly used for the desalination of water. As seen in a recent study in South Africa, tests were run using polymeric nanofiltration in conjunction with reverse osmosis to treat brackish groundwater. These tests produced potable water, but as the researchers expected, the reverse osmosis removed a large majority of solutes. This left the water void of any essential nutrients (calcium, magnesium ions, etc.), placing the nutrient levels below that of the required World Health Organization standards. This process was probably a little too much for the production of potable water as researchers had to go back and add nutrients to bring solute levels to the standards levels for drinking water. On another note, providing nanofiltration methods to developing countries, to increase their supply of clean water, is a very inexpensive method compared to conventional ones. However, there remain issues as to how these developing countries will be able to incorporate this new technology into their economy without creating a dependency on foreign assistance. [3]
References
- ^ Water Quality & Treatment, 5th Ed. American Water Works Association, 1999.
- ^ Nanofiltration Membranes and Applications
- ^ Hillie, Thembela; Hlophe, Mbhuti (2007). "Nanotechnology and the challenge of clean water". Nature Nanotechnology 2: 663-664. doi:10.1038/nnano.2007.350.
See also
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