NTU’s membrane invention: Centrifugal Reverse Osmosis technology – featured in GWI Water Desalination Report
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The increase in demand for freshwater during the 20th century has led to a global water-scarcity crisis suffered by 40% of the population in the world. The situation is exacerbated by contamination of freshwater resources, global climate change, industrialization, and rapid population growth. Less than 0.008% of the water on this earth is available for its current population of 7.7 billion people. The only way to increase our available freshwater supply is through desalination of seawater. Desalination via reverse osmosis (RO) membrane technology now dominates the world market. However, an endemic problem of RO desalination is its high-cost relative to freshwater sources. A major contributor to this disparity is the high-pressure pumping cost for RO.
Centrifugal reverse osmosis (CRO) can significantly reduce the pumping cost for RO because it operates close to the minimum energy required for separating freshwater from saltwater. It does this by rotating a membrane module to cause a centrifugal pressure that increases with increasing distance from the axis-of-rotation. As such, the local pressure is only slightly higher than the minimum required for RO. In contrast, conventional RO desalination employs a high-pressure pump to operate the entire membrane module at the maximum pressure. This novel CRO technology can reduce the energy required for a 50% recovery of freshwater from a typical seawater feed by over 30%.