The main objective of this research was to determine the integrity of reverse osmosis (RO) and nanofiltration (NF) membrane
systems with respect to microbial passage using both microbial- and non-microbial surrogates.
The focus of this paper is to present the results from pilot-scale tests. Pilot-scale experiments were conducted at two sites: Water Factory 21 (WF-21) at the
Orange County Water District (OCWD) in Fountain Valley, Califormia and the Northwest River Water
Treatment Plant (NWR-WTP) in the City of Chesapeake, Virginia. The source waters used were
micro-filtered secondary effluent (MFSE) for the WF-21 tests, and conventional process-treated
river water (CTRW) for the NWR-WTP tests. Waters from WF-21 and NWR-WTP were
selected to reflect two generic types of source waters, i.e., surface waters and reclaimed
wastewater effluent, for which disinfection or removal credit for pathogens by RO and NF would
be most likely required.
Two units were employed for testing in WF-21: a dual-element test unit (DETU) and a multi-stage test unit (MSTU). The DETU consisted of two pressure vessels
arranged in series, operated in single-pass mode with no concentrate or permeate recycle to the
feed. The ESPA1 RO element was operated in the lead vessel and the TFCS NF element in the
trailing vessel. The test surrogates were injected into the feed line using an electromagnetic
dosing pump. Pressure was measured in the feed and concentrate of each vessel using a single
pressure gauge coupled to a 4-way selector valve. Permeate flow rate in each vessel and the final
concentrate flow rate were measured using in-line flowmeters. Samples were collected from the
feed (from an in-line sample port), the permeate from each vessel, and the final concentrate. The
MSTU setup consisted of two separate flow streams in parallel each with two vessels in series
(i.e. four lead vessels) followed by combined flow with a series of two vessels in series. Each vessel was designed to hold three spiral-wound elements. Permeate flows were
regulated by a valve located in the final concentrate line. Permeate and concentrate flow rates
were measured using in-line flowmeters. A single pressure gauge coupled to a four-way selector
valve was used to measure the pressure difference between feed and concentrate at different
locations (i.e., vessel 1&2, 3&4, 5, and 6). Samples were collected from the feed, final
concentrate, individual vessel permeates and combined permeate through in-line sample ports. Includes 7 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 420 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 14 |
| Published : | 06/16/2002 |
