Hiroyuki Yamamura

High recovery/high pressure membranes for brine conversion SWRO process development and its performance data

Toray Industries and Toray Engineering have developed a new type reverse osmosis (RO) membranes and its process for seawater desalination, which brings advantages of high water recovery, low energy cost and lower plant installation cost. The new type RO membranes, “Brine Conversion Reverse Osmosis Membrane (SU-820BCM)”, shows a superb performance at a high pressure of more than 9.0 MPa and a high salt concentration more than 5.8% concentrated seawater. The newly developed “Brine Conversion Seawater Reverse Osmosis Desalination System (BCS system)” takes the fresh water from the concentrated brine water (salt concentration 5.8%, produced under 6.5 MPa) of first stage RO modules. The newly developed “Brine Conversion Seawater Reverse Osmosis Desalination System” (BCS system) can obtain 60% recovery of fresh water, taking from the concentrated brine water (salt concentration 5.8%, produced under 6.5 MPa) of first stage RO modules in addition to a conventional system desalination (40% recovery). The cost of producing fresh water can be saved approximately 15–20%. The space of plant is also reduced approximately 30% due to reducing the space of the pretreatment process. The continuous operating performance with SU-820BCM has proved to be in good conditions in the BCS pilot plant in Japan for more than 2 years. The total capacity of this plant is 210 m3/d with 60% recovery, and the quality of the produced fresh water has been maintained at the level of less than 200 ppm TDS, which satisfies their designed specifications for drinking water.

Operation and reliability of very high-recovery seawater desalination technologies by brine conversion two-stage RO desalination system☆

Abstract A reverse osmosis (RO) seawater desalination system has many advantages such as saving energy and using less installation space, and has become regular technology to obtain fresh water from seawater. A significant way to lower energy and installation space is to raise system recovery, and we have developed a new RO seawater desalination system which provides 60% recovery of fresh water for 3.5% seawater. The new technology is called a brine conversion two-stage SWRO system (BCS). This system includes several new technologies such as system configuration, energy recovery, operating condition, etc.; high-performance membrane technology; anti-biofouling technology and a new analysis method. A pilot plant has been operated successfully at Torays Ehime plant site since 1997. The first commercial plant of 4500m3/d (1.2 mgd) has been operating successfully since March 1999 in Mas Palomas (Gran Canaria, Spain). The Tortola and Curacao plants in the Caribbean have been installed with the full BCS (first-+second-stage RO system), and also operated under good conditions. A new application of the BCS, installed at the Muroto plant in Japan, has been in operation to obtain bottled drinking water and high concentrated mineralized water from deep seawater. Furthermore, other plants are under construction in Spain and the Caribbean. The BCS is presumed to be the standard SWRO system for the 21st century.