Leveraging Nanotechnology for Next Generation Seawater Desalination (The International Desalination & Water Reuse Quarterly) - July 28, 2009
NanoH2O advanced membranes for reverse osmosis (RO) desalination represent a new material that enhances current polymerbased membranes with the benefits of nanotechnology. These nanocomposite RO membranes represent a step-change in productivity through improved permeability while maintaining requisite salt and contaminant rejection.
By leveraging existing membrane synthesis techniques, NanoH2O’s advanced thin-film nanocomposite TFN) membrane technology requires few modifications to existing commercial manufacturing facilities and fits within current desalination pressure vessels without alteration.
Proven polymer technology combined with novel nanomaterials during TFN synthesis are the key to proved NanoH2O membrane performance characteristics, including the potential for fouling resistance to reduce energy consumption, sustain higher system flux and limit chemical usage. TFN membranes allow systems to be engineered and operated in a more efficient manner – either through energy savings or higher productivity.
NanoH2O advanced early research performed at UCLA by Dr Eric Hoek to develop nanocomposite membranes. Dr Hoek’s mixed matrix membranes used zeolite nanoparticles dispersed within a traditional polyamide thin film. In his work, zeolite nanoparticles were dispersed in one of the two monomer solutions used to create the membrane by the interfacial polymerization process. Incorporation of these nanoparticles into a brackish water reverse osmosis (BWRO) membrane formulation increased permeability and altered surface properties potentially related to fouling, while maintaining salt rejection. Since the original publication of this concept, further development and optimization of this membrane technology for seawater reverse osmosis (SWRO) has resulted in an enhanced flux of more than double that of a 22.7 m3/d (6,000 gpd) commercial baseline with 99.7% salt rejection.
Recent seawater field testing of an industry-standard spiral-wound element module including the TFN material combined with a fabric support base topped with a microporous polysulfone layer has supported current laboratory research findings.
Performance and economic modeling demonstrate that a conventional 10 MGD (37,850 m3/d) plant using membrane elements with twice the flux of a standard 6,000 gpd element would produce up to 70% more water for the same size plant or the plant could be run at lower pressure and produce the same amount of water while consuming 20% less energy. Alternatively, a plant could be built that would produce the same amount of water as the conventional plant, but would be 40% smaller. NanoH2O’s initial SWRO TFN
membrane product will be commercially available in early 2010.