Last update:
11/09/2004
Membrane Selection and Operating Conditions - Diagnostic Studies and Development of Test Protocols
Inland waters (e.g., brackish groundwater and agricultural drainage water, high salinity surface water and seawater) are complex mixtures of dissolved and suspended chemical species that also may contain a wide variety of micro- organisms. Membrane performance may vary significantly with water composition, which in turn may vary depending on geographical location. In the present program, which is in support of a number of membrane desalination field studies diagnostic protocols are being developed to compare the performance of commercial membranes with respect to salt rejection, flux, bio-fouling potential, mineral scale fouling and response to antiscalant treatment. Fouling by suspended particles, microorganisms and mineral scaling can severely impede membrane performance and longevity. Therefore, membrane performance and fouling resistance must be considered when selecting an operational membrane. In the present approach, commercial and research grade membranes are being evaluated using both diagnostic solutions and field water samples. Membrane performance (including fouling and scaling propensity) are being evaluated, over a range of conditions, in a laboratory dual-cell membrane test unit. Bio-fouling potential is evaluated via a batch bio-fouling assay. In addition, propensity for mineral salt precipitation is evaluated in both batch crystallization cell and in membrane scaling studies. The effectiveness of leading anti-scalants (in terms of the incipient precipitation time) is ranked and correlated with antiscalant dose and initial level of solution supersaturation. Diagnostic protocols developed in our laboratory have already proven effective in guiding the selection of candidate membranes for field studies and membrane autopsies.
The above work is sponsored, in part, by the California Department of Water Resources (DWR) and involves a collaboration with the DWR.
References
Ron-Wai Lee, Julius Glater, Yoram Cohen, Chris Martin and Kurt Kovac, Martin N. Milobar, Dan W. Bartel, "Low-pressure RO membrane desalination of agricultural drainage water", Desalination, 15, 109-120 (2003).
Diagnostic Laboratory RO System
Biofouling potential for selected RO membranes following the method of Ridgway et al (1999) as described below.
