Characterization of U.S. Seawaters and Development of Standardized Protocols for Evaluation of Foulants in Seawater Reverse Osmosis Desalination
Samer Adham, Ph.D., MWH
Desalination technologies using reverse osmosis (RO) membranes have been in development for more than four decades. Although significant advances in membrane technology have been developed to efficiently operate seawater RO (SWRO) systems, control of membrane fouling still seems elusive. Because of seawater’s complex matrix, characterization and identification of the nature of foulants responsible for decreased SWRO performance are incomplete.
In this study, a systematic approach to study organic fouling and determine the key foulants depositing on the membrane surface is presented. The objectives of the study were to characterize seawater from various locations in the United States, evaluate methods for characterizing clean and fouled membranes, identify organic foulants using bench-scale RO experiments, study the influence of membrane properties and algal bloom (red-tide events) on organic fouling, and compare fouling between bench-scale SWRO operation and pilot-scale SWRO operation.
Seawater from West Basin Municipal Water District (WBMWD), Carlsbad Desalination Project (CDP), Tampa Bay Desalination Plant (TBDP), and South Bay Power Plant (SBPP) was chosen as the feed water sources for this study. Membranes used in the study were DowFilmtec SW30HR, Hydranautics SWC4, and Saehan SR. To test the different seawaters for fouling propensity, a bench-scale RO unit was constructed at MWH in California and University of Illinois, Urbana-Champaign (UIUC). Experimental results and evaluation of methods for determining organic fouling in seawater are presented in detail in this study.
The techniques and methods used in this study can be used prior to the operation of a pilot-scale process in order to access the nature of foulant material that would preferentially deposit on the membrane surface. The bench-scale experiments must be combined with the various analyses, characterizations, and autopsy techniques described in this study to obtain meaningful results. An understanding of the nature of foulant will facilitate cost-effective and optimal design/operation of pretreatment and the overall SWRO process.
(2011, 66 pages, 06-014-1)
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