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Toray Develops New RO Membrane Element that Has Twice as Much Water recovery

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Apr. 17, 2019

Toray Industries, Inc.

　Toray Industries, Inc. (head office: Chuo-ku, Tokyo; President: Akihiro Nikkaku; hereinafter referred to as “Toray”) announced today that it has developed a new small-sized reverse osmosis (RO) membrane element with dramatically improved water recovery*1. Highly efficient water generation with energy saving is enabled through a technology that limits the resistance of the feed water*2 and purified water*3 flowing through the RO membrane to the minimum, thus boosting the velocity of flow of feed water. Toray will carry out global demonstrations to expand the scale and apply the technology in large-scale, industrial use RO membrane elements.
　RO membrane elements are used in the purification of various types of water and development of the technology to further improve water recovery performance is required to respond to the worsening water problems around the world every passing year.
　An RO membrane element consists of an RO membrane sandwiched between the main elements of permeate side channel material and feed side channel material. To boost water recovery, it is necessary to lower the flow esistance*4 of the permeate side flow channel and reduce the ion concentration of RO membrane surface.
　The key technology points are as follows.

1. New design of the permeate side channel material using precision polymer processing technology
　Toray applied its fluid analysis, structural analysis technology and fiber processing technology it has cultivated over years to develop the new channel material. It succeeded in expanding the channels by forming in the striped shape while maintaining the required pressure resistance with fine and precise molding of molten resin. The technology realized a 50% reduced in flow resistance on the permeate side (Fig. 1).

2. Design of a new feed side channel material employing fluid analysis
　When RO membrane element is operated with improved water recovery (Fig. 2), ion concentration on the surface of the RO membranes rises resulting in diminished separation performance.
By making full use of fluid analysis, Toray succeeded in developing a new feed side channel material which has thinner and less number of nodes so that it can increase the flow velocity of feed water to more than twice and reduces the ion concentration on RO membrane surface by more than 30% compared with before (Fig. 3).

　By combining the above two innovative technologies, Toray succeeded in improving water recovery by as much as twice compared with existing RO membrane elements of various sizes (Fig. 4).

　In the Toray Group Sustainability Vision announced in July 2018, Toray declared contributing to solving the water scarcity faced by the world and reducing the burden on the environment by utilizing water treatment membrane technology as its mission. 　Toray plans to exhibit the RO membrane element using these technologies at the 2019 WQA CONVENTION & EXPOSITION, a tradeshow for RO products used in water purifiers, to be held from April 23 to 25 in Las Vegas, the U.S.

[Figures]
Fig. 1 Performance of the permeate side channel material used in this technology
Fig. 1 Performance of the permeate side channel material used in this technology
Fig. 2 Water recovery of RO membrane element
Fig. 2 Water recovery of RO membrane element
Fig. 3 Performance of the feed side channel material used in this technology
Fig. 3 Performance of the feed side channel material used in this technology
Fig. 4 Performance of RO membrane element used in this technology
Fig. 4 Performance of RO membrane element used in this technology

[Glossary]
*1 Water recovery
Volume of permeated water when the amount of feed water to RO membrane element is set as 100.

*2 and 3 Feed water and purified water
In the water treatment process using RO membranes, water that is passed through the element is called feed water and is distinguished from the water that emerges after passing through the membrane, which is called purified water.

*4 Flow resistance
Friction loss caused by contact with channel material when water flows through the channels in the RO membrane element. Flow amount can be increased when flow resistance is lowered, which increases the amount of water treated.

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