New technology for more efficient pretreatment of seawater in advance of desalination was recently developed in Japan. It makes the membranes used to filter out salt less liable to plugging, and enables filtration at a flow rate ten times that at present. It is consequently projected to reduce the cost of pretreatment by about half. Sumitomo Electric Industries, Ltd., which developed it, plans to conduct proving tests and inject it into the market in fiscal 2012.
Sand and membranes are generally used to remove salt in the pretreatment process of seawater desalination. Sand filters, however, cannot exclude fine jelly-form particles contained in large quantities in seawater. Use of membranes results in a lowering of the flow rate due to membrane plugging. The incidence of plugging requires the installation of large-area membranes that drive up the cost.
The TT (TEP Trap) membrane developed by Sumitomo Electric Industries is made of polytetrafluoroethylene (PTFE). In structure, the technology consists of bundles of extremely fine fibers, and the membranes are less liable to plugging. In addition, a backwashing mechanism, which flushes the membranes with water flowing in the opposite direction, is used to remove particles affixed to the membrane.
