Pretreatment options for large scale SWRO plants: case studies of OF trials at Kindasa, Saudi Arabia, and conventional pretreatment in Spain

Development of an Environmental Impact Assessment and Decision Support System for Seawater Desalination Plants

“…An SDI range of 2-4 is typically required by membrane manufacturers for conventional pretreatment. UF/MF has a reported SDI range of 0.8-2.2 [50,99,107,112,119,126], and beachwells have reported values of 0.4-2.8 [58, 60, Tables 3 to 7, page 29ff.]. Concerning ecological impact, it is assumed that the open intakes of UF and conventional pretreatment systems have the potential to cause the impingement and entrainment of marine organisms ('yes'), which is not the case for beachwell intakes ('no').…”

“…Doses ranged between 0.2-2.8 mg/l as Fe (ten studies) and 0.1-10 mg/l as FeCl 3 (ten studies). Many studies found that pre-coagulation improved the UF/MF performance in terms of UF/MF fouling or filtrate quality [e.g., 99,101,112,119]. Although UF generally performed well in terms of particles and microorganisms removal, a few studies found UF/MF to be less efficient in terms of TOC removal than conventional pretreatment [105,107], or observed irreversible fouling [122].…”

“…Chlorine levels in CEB varied between 5-20 mg/l every 15-40 minutes [i.e., every backwash, 98,99,101,119,123], to 20-50 mg/l every 2-6 hours [112,117], up to 100-500 mg/l once or twice per day [98,100,102,107,110,120,121]. These values show a higher upper range than the results of a review carried out by Fritzmann et al [126], who reported chlorine levels of 10-200 mg/l in CEB of UF/MF membranes.…”

“…Other membrane suppliers which produce insideout UF membranes are Hydranautics, Inge and Aquasource. Their chlorine dose levels range from 5 mg/l every 30 minutes [119, for Aquasource] to 20-50 mg/l every 2-6 hours [92,93,112,[115][116][117], for Hydranautics, Inge] in pilot plants. Doses in full-scale plants are lower and less frequent with 20 mg/l every 8-24 hours [92][93][94].…”

Study on the removal of biodegradable NOM from seawater using biofiltration

“…A considerable number of reports can be found in the literature associated with conventional and membrane pretreatments (Rosberg, 1997;Vial et al, 2003;Halpern et al, 2005;Bonnelye et al, 2008;Voutchkov, 2010, van Hoof et al, 1999Brehant et al, 2002;Pearce et al, 2004;Kumar et al, 2006;Xu et al, 2007;Lorain et al, 2007;Bonnelye et al, 2008;Shon et al, 2008;Salinas Rodriguez et al, 2009). Nevertheless, dosages of biocides (often chlorinated substances) are the currently employed common strategy to prevent biofouling because biocides can kill nearly all microorganisms.…”