[show abstract][hide abstract] ABSTRACT: The removal of bacteriophage MS2 and fluorescent-dyed polystyrene microspheres with intact and purposely compromised spiral-wound RO membrane elements was investigated. MS2 rejection with intact membrane elements was >99.9995%. A model developed for data evaluation revealed that the advective passage of MS2 through imperfections of intact membrane elements was <2 x 10(-5)% of the overall product water flow produced. The advective passage of MS2 and microspheres through a pinhole induced in one of the elements was 0.05-0.1% of the overall product water flow. Prolonged testing of both intact and compromised elements resulted in increased MS2 rejection corresponding to advective MS2 passage through membrane imperfections of <3 x 10(-7)% of the overall product water flow. The permeate flow rate obtained with an element with a larger pinhole was 5-13% greater than that of the intact element, and the corresponding rejection of MS2 and microspheres was similar to that observed for sodium chloride. The use of a cracked o-ring in the connection of the permeate tube to the element vessel end-cup resulted in advective passage of MS2 through the crack of <0.0001% of the overall permeate flow.
Water Research 11/2004; 38(18):3821-32. · 4.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: This paper describes pilot-scale studies that examined three integrity test methods for: (1) quantifying virus removal by nanofiltration (NF) and reverse osmosis (RO) membrane systems when arranged in single element unit and two-stage system configurations, and (2) determining change in virus removal capability of such systems when subject to different types of membrane/o-ring compromisation and fouling. The three methods evaluated included one biologic type (MS-2 phage), that has been employed previously; and two, new non-biologic types (24-nanometre polystyrene fluorescent dyed microspheres and fluorescent Rhodamine WT (R-WT) dye, molecular mass 496 daltons). All three surrogates were employed in a manner intended to show a minimum of 4-logs removal by the NF and RO membranes selected for test. Methods of compromisation included a pinhole induced through one membrane leaf in the spiral wound NF/RO element, and both cracking of and removal of sections from one of the permeate tube o-rings. Testing was conducted on two source waters, representing brackish surface water and effluent categories: a microfiltered secondary effluent and a river water. The river water is characterized by low to moderate TDS and high TOC and was treated with conventional alum coagulation, flocculation, sedimentation and granular media filtration for subsequent membrane processing. Keywords Fluorescent microspheres; membranes; MS-2 phage; nanofiltration; reverse osmosis; Rhodamine WT dye; virus removal