Water. Desalination + reuse
Issue link: https://read.utilityweek.co.uk/i/258379
RESEARCH February-March 2014 | Desalination & Water Reuse | 29 | • Easily controllable, to cope with variations in foulants and RO systems. It would also need to work within the parameters of flow rate and pressure determined by the main membrane manufacturers. Max Fazel began by inducting air from the atmosphere using a simple, laboratory- scale device, and applying it directly to a submerged membrane sample. He found that the bubbles created in this way quickly coalesced and passed over a defined, limited area of the membrane surface, barely interacting with the foulant. Alongside working on this project, Fazel was developing new products for removing organic foulant to add to the company's solid formulation Genesol range. One of these was Genesol 704, a high pH detergent, surfactant and chelant mix. The team discovered that when they used the original air generation technique in conjunction with Genesol 704, the bubbles became much smaller. The formation of these microbubbles increased the turbulence of the cleaning solution, leading to an improved cleaning effect. Crucially, the bubbles also covered the entire membrane surface. Early testing of this dual approach, using membrane samples from operational RO plants heavily fouled with iron and manganese, produced encouraging results. The team observed that the foulant was completely removed and flux restored by around 30% within 20 minutes, compared with standard cleaning recommendations of 2-4 hours. These results caused Genesys to fundamentally question its existing approach to membrane cleaning. THE RigHT mix The purpose of the CIP process for RO membranes is to remove the maximum amount of foulant, therefore reducing the frequency of cleaning needed. The company developed its Genesol range with this in mind, to help customers clean their membranes with maximum efficiency as quickly as possible, keeping downtime to an absolute minimum. Since 2001, the firm's partners at Genesys Membrane Laboratories in Madrid have performed over 500 autopsies on membranes from RO plants facing serious fouling challenges. Their experience has shown that problems are rarely caused by a single foulant. In most cases many different foulants are present, and these interact with each Physical bubble generation and water produces bubbles of 1-2mm the size of the membrane spacer A flat sheet test rig enabled Genesys to observe and film bubble activity at the membrane surface