Polyamide Reverse Osmosis Membrane Fouling and its Prevention: Oxidation-Resistant Membrane Development, Membrane Surface Smoothing, and Enhanced Membrane Hydrophilicity
Separation Systems Technology, Inc; San Diego CA.
Orange County Water District; Fountain Valley CA.
Report #61 - Conclusions -
The search for a chlorine-resistant PA membrane was begun some 22 years ago and has continued since.
This project, while modest in funding and duration, possessed both depth and scope in pursuing a new approach; that is, to select the reactant pairs using moleular modeling for forming a PA membrane on the basis of steric differences.
A major thrust of the project involved the synthesis, separation, and purification of cis, trans, cis, trans-1,2,3,4-cyclohexanetetrabarboxylic acid chloride from a mixture of six sterioisomers; analysis of the purified products were determined by C-13 NMR, H-NMR, P-31 NMR, GCMS, FT-IT, and ATR/FT-IR spectrometry.
Membranes were prepared from the purified isomer and the RO transport properties optimized for water flow, salt rejection, and chlorine tolerance.
The membranes were further characterized with respect to bacterial attachment (biofouling), surface charge, air bubble contact angle determinations (hydrophilicity), surface morphology by atomic force microscopy, and chemical and structural analysis by both FT-IR and ATR/FT-IR spectrometry.
Chemical modifications of the membrane surface were made to reduce biofouling.
Finally, an ambitious field RO test program was carried out with the optimized PA membranes using chlorinated feed waters at the Water Quality Improvement Center, Yuma, AZ on surface waters and at the Orange County Water District, Fountain Valley, CA on municipal wastewater.
The initial results of those long-term RO tests are very promising.
For more information about the DWPR program, contact Kevin Price at: Bureau of Reclamation, 86-69000, PO Box 25007, Denver CO 80225; phone (303) 445-2260; or e-mail a message to MPrice@usbr.gov.