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The TDS contents of freshwater, brackish water, and seawater are defined as

follow :

Freshwater <500 ppm

Brackish 500-15000 ppm

Seawater >35000 ppm

Figure 2.1 TDS contents of water types.

2.2 Seawater desalination methods

Water desalination processes remove salts and other minerals from water.
desalination processes are divided according to:

1- Extraction base, refer to what we extract from saline water. We have two
choices :

A- Water extraction.

B- Salts extraction.

In water extraction, the main process is to extract water from saline water by
evaporating it (Thermal desalination) or by pressurized it in membranes (Reverse
osmosis desalination RO).

On the other hand, in salts extraction, the main process is to extract salts from saline
water by (Electrodialysis Reversal EDR) or by ionic exchange.

EDR

Salts

extraction Ionic
exchange
Desalination
Figure 2.2 Extraction base classifications.
RO
Water
extraction
Thermal
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