Water. desalination + reuse

| 28 | Desalination & Water Reuse | February-March 2014 RESEARCH _________ Matt Armstrong, sales and marketing manager, Genesys ___ Editor's Note: At the IDA World Congress in Tianjin last October, a team from Genesys International launched an innovative new membrane cleaning system powered by microbubbles. Genesys sales and marketing manager, Matt Armstrong, tells the story behind Genairclean DRIVEN BY rising demand from customers for a more efficient way to clean their reverse osmosis (RO) membranes, the Genairclean system is the result of a three-year in-house research and development programme. A growing proportion of RO plants are operating on wastewater or recycled water. Typically these are high silt density index (SDI) waters with a high potential for organic fouling and biofilm growth. Even with robust pretreatment systems, using a post membrane bioreactor (MBR) or ultrafiltration (UF), plants with such challenging feed water need more intensive and more frequent cleaning than normal brackish water (BW ) systems. This means increased costs and downtime. BuBBling inspirAtion For some time Genesys' senior R&D chemist, Max Fazel, had been keen to explore the hypothesis that air could be used to enhance the effectiveness of chemical cleaning methods. Previous tests of using compressed air to assist with the cleaning of spiral-wound RO membranes had yielded poor results. Bubbles had formed over only a limited area of the surface and the potential for membrane damage increased. However, Fazel was convinced that a different approach to applying the air could avoid these problems and increase the effectiveness of cleaning chemicals. In 2010, managing director Steve Chesters secured a grant from the Technology Strategy Board and UK government that enabled Genesys to invest in the equipment and facilities needed to put Fazel's theory to the test. EffEct of BuBBlEs on foulAnt The development team set to work to develop an effective way to produce bubbles that would cover the entire surface and help to lift organic foulants from spiral-wound RO membranes. Their hypothesis was that the right type of bubbles can: • Completely cover the surface of a spiral-wound membrane without damaging the polyamide layer • Increase the removal of organic-based RO membrane foulants. To prove the hypothesis they would need to visualise and measure the effect of bubbles on the foulant at the membrane surface. However, due to the structure of spiral-wound membranes, it is impossible to know exactly what is happening at the surface when bubbles are introduced. Genesys sought technical assistance from one of its longstanding distributors, Salt Separation Services – designers and manufacturers of specialist desalination equipment for the marine and off-shore industry. Directors Daniel Shackleton and Steve Grindrod designed and built a bespoke flat sheet test rig (FSTR) with a polycarbonate viewing window. Used in conjunction with an endoscope, this equipment would enable the lab team to observe and film the action of bubbles on foulant directly at the membrane surface. optiMising BuBBlE gEnErAtion And sizE In order to develop a commercially viable process, Genesys realised that its bubble-generation technique would need to be: • Energy neutral • Easy to install onto existing cleaning in place (CIP) systems From concept to launch in three years: Genairclean's story

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