Conwed, a plastic netting manufacturer, collaborated in a water research study that developed a method to obtain accurate three-dimensional (3D) geometry representations for any feed spacer design from X-ray computed tomography (CT) scans. The study titled “Characterization of feed channel spacer performance using geometries obtained by X-ray computed tomography” and published by Elsevier – Journal of Membrane Science, Volume 522, (2017), 124-139 – is an example of the reverse osmosis (RO) collaborative efforts Conwed pursues with industry and academic researchers and scientists to expand the knowledge about RO feed spacers and their impact on pressure drop, membrane damage and biofouling; the top three challenges in every RO system.

Conwed manufactures feed spacers for industrial, sea water reverse osmosis (SWRO) and brackish water reverse osmosis (BWRO) systems. In recent years, the technology and innovation team at Conwed has proactively looked for alternative technologies to help address pressure drop, membrane damage and biofouling from a feed spacer developer’s perspective. Exploring feed spacer design and composition to impact performance has taken Conwed to utilize new technologies such as 3D printing, to shorten the development process between initial design and full production.

“Innovation in reverse osmosis has historically come from membrane manufacturers. However, we decided to proactively look into the spacer for alternative designs and technologies that could positively impact overall performance, but from the feed spacer standpoint. So, collaborating with industry and academic researchers to advance understanding of the role of feed spacers in RO has been and continue to be one of our main goals,” says Ivan Soltero, senior strategic marketing manager at Conwed.

Research into feed spacer design has concentrated on the effect of the feed spacer geometry on the hydrodynamics in the feed spacer channel. Hydrodynamics, subsequently, can influence other performance indicators, provide potential flow patterns and estimate shear stress on filaments and membranes. This new study shares the conclusions of using X-ray CT to obtain accurate three dimensional geometry representations of feed spacers and to model impact on flow characteristics in the feed channel.

Alternating Strand Design (ASD) by Conwed, was one of the feed spacer geometries tested in this study, which was found to provide a lower pressure drop while being highly efficient in converting pumping power into membrane shear. “Our technology and innovation team is rapidly breaking paradigms in feed spacer design. Our alternating strand design is an example of how we can explore new avenues to impact pressure drop, membrane damage and biofouling. We believe the next wave of innovation will come from the feed spacer,” says Soltero.