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To evaluate the cleaning efficiency of various protocols, an ultrafiltration membrane pilot skidwas operated for several months using settled water produced from the Seine Riverdownstream of Paris in order to simulate membrane fouling conditions that would beexpected in a typical water treatment plant. The pilot skid was equipped with micromodulesto allow for the comparison of different cleaning procedures given the same state of fouling.Cleaning procedures were evaluated with the objectives of simplicity, rapidity and costeffectiveness.To address these goals, a focus was placed on the use of commoditychemicals such as sodium hypochlorite and caustic soda which are commonly used in watertreatment. The specific protocols used were selected according to the quality of theultrafiltration membrane feedwater (settled water quality) and the level of foulingexperienced.Several parameters were studied in order to identify a suitable cleaning procedure. Theseincluded the order of chemical addition, the cleaning mode utilized (filtration, circulation, orsoaking) and the contact time employed. Additionally, the combined effect of sodiumhypochlorite and caustic soda was also evaluated.The efficiency of each cleaning procedure was monitored by measuring the membranespecific flux recovery as well as the evolution of fouling components within the cleaningsolution. For analysis of organic matter, ultraviolet (UV) absorption and GC-MS were utilized. Removal ofinorganic foulants was followed using ICP analysis of aluminum, manganese, and ironconcentrations.Results demonstrated that a cleaning solution containing a mixture of sodium hypochloriteand caustic soda was the most effective cleaning protocol for removal of fouling due toorganic matter and aluminum salts. In most cases a simple soaking of the membrane orcirculation of the cleaning solution for a one hour time period was sufficient to recover morethan 90% of the initial permeability. Includes 7 references, tables, figures.

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Edition: Vol. - No. Published: 03/05/2003 Number of Pages: 13File Size: 1 file , 530 KB