Seawater Desalination by RO

Modern distillation plants have unit capacities of about 25,000 t/d. The energy consumption is approximately 95 KWh/to distillate in the form of saturated steam of a pressure of about 2.2 bar and 4 to 5 KWh/to distillate in form of power for the pump drives. All distillation processes produce a distillate containing only 20 to 30 ppm salts (total dissolved solids). Reverse osmosis (RO) will be the alternative to distillation. The modules which are successfully employed are of the spiral wound or the hollow fiber configuration. Under favorable conditions, the economic service lifetime of the modules resp. the membranes is about 5 years and warranties for such a figure are given by manufacturers. 

RO plants are, however, much more sensitive to insufficient feedwater pretreatment than thermal plants. For this reason, it is accepted technology to use well water from wells drilled at the seashore rather than surface water as in thermal desalination. 

In general, the following measures have to be considered for feed pretreatment of RO seawater plants 18 

13 March 1983 (400 Operating Hours) k Before cartridge filters c 804 of permeators installed 

---