Desalination brackish waters

The concentration of brackish water is far more variable than seawater. Depending on the location, brackish groundwater can have TDS concentrations ranging from several hundred up to several thousand mg/L. Table 2.2 shows the ion concentrations from the feed of three brackish water desalination plants in the Emirate of Abu Dhabi, United Arab Emirates. It can be seen that even three water sources in the same region can have widely variable concentrations of dissolved salts. 

Data from the Al Wagan BWRO desalination plant (Mohamed et al. 2005) has been used to highlight a typical brackish water desalination scenario. The following has been calculated assuming 200 m /day of brackish water is treated at a recovery of 70%. From Eq. 2.1 ... 

FIG. 11 Simplified schematic of a modern ED brackish water desalination plant. 

In the case of clarified feeds and low current densities, membrane lifetime can be as long as seven or 10 years for brackish water desalination or drinking water nitrate removal, respectively. However, if the feed solution is fouling or scaling or the ED separation plant has not been well designed or is not properly conducted, membrane lifetime is no longer than a year. 

Seawater and brackish water desalination membranes operated with 0.5 to 5 wt% salt solutions at pressures of 200-1000 psi. 

M. Hamada, Brackish Water Desalination by Electrodialysis, Desalination Water... 

Seawater and Brackish-Water Desalination with Membrane Operations... 

Another interesting possibility is the use of pressure-driven membrane processes, in particular MF and UF are becoming standard and very efficient pretreatment options for sea- and brackish-water desalination. Also, for wastewater treatment, MF/UF pretreatment technology can efficiently reduce the highly fouling nature of the feed. 

Another field where membrane contactors are studied in the logic of the process intensification is seawater and brackish-water desalination. The scarcity of... 

Atomic force microscopy (AFM) studies contribute also to the improvement of the NF membranes, especially for desalination of brackish water. AFM characterization of a series of commercial NF and RO membranes of different polymer types for brackish water desalination had not been attempted, so far. Thus, as reported by Hilal [79], it is imperative to study the properties of these membranes and to show that the characteristics obtained from AFM correlate to the process behaviour. This is expected to provide substantial new insights into the influence of NF/RO membrane properties on performance, providing a database for the selection of NF membranes to account for the complexities of brackish water. 

M. Pontie, H. Buisson, C.K. Diawara, H. Essis-Tome, Studies of halide ions mass transfer in nanofiltration - application to selective defluorination of brackish water, Desalination 157 (2003) 127-134. 

H. Dach, J. Leparc, H. Suty, C. Diawara, A. Jadas-Hecart, A. Lhassani, M. Pontie, Innovative approach for characterization of nanofiltration (NF) and low pressure reverse osmosis (LPRO) membranes for brackish water desalination, Desalination, 2006 (submitted). 

Table 1.1 Development of RO membranes for brackish water desalination.

Economics The largest application for RO and NF is water treatment. Brackish water desalination for drinking water is the largest. 

REVERSE OSMOSIS IN SEAWATER AND BRACKISH WATER DESALINATION... 

J. Passanisi, Project Compares Brackish Water Desalination Technologies. Part 1, Waterl Engin. Manag. 149(2), 14—17, Feb. (2002). 

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