Brackish water condition commonly occurs when fresh water meets sea water. In fact, the most extensive brackish water habitats worldwide are where a river meets the sea.
The term "brack" or Brackish was first used to describe bodies of waters that had been mixed with seawater in the 1500s, Brackish Water was not as salty as seawater, yet very distasteful, and was described as harmful water due to its characteristics and to unique microorganisms that caused human illness .
Well Water - Brackish Water - Borehole Water
Brackish water usually contains from 0.5 to 30 grams of salt per liter (500 to 30,000 ppm or mg/L); however, the brackish water salinity concentrations may vary considerably over space and time.
In general Brackish Water is a term for water that contains a significant concentration of dissolved salts (Na Cl). The concentration is usually expressed in parts per million (PPM) or milligram per liter (mg/L) of salt. Brackish Water that is saline contains significant amounts (referred to as "concentrations")
The salinity concentration is the amount of salt in the water by weight, as expressed in "parts per million" (PPM). For example if water has a concentration of 5,000 ppm of dissolved salts, then one percent (5,000 divided by 1,000,000) of the weight of the water comes from dissolved salts.
The salinity concentration level used by US Geological Survey classifies brackish water in three categories.
1- Slightly saline water contains around 1,000 to 3,000 ppm.
2- Moderately saline water contains roughly 3,000 to 10,000 ppm.
3- Highly saline water has around 10,000 to 35,000 ppm of salt.
Brackish Water can be found in wells, boreholes, mangrove swamps, inland lakes and seas. The Caspian Sea, which is very famous for the great sturgeons fish (source of the best caviar in the world), is the largest brackish lake in the world with a salinity level of 1.2% (12,000 PPM), about one-third that of normal seawater. The Baltic Sea is another example of brackish water, the Baltic Sea has the least Saline concentrations in the world with a salt concentration of 0.5% (5000 PPM) compared to the Red Sea and the Persian Gulf both with a salt concentration of about 4.5% (45,000 PPM)
Brackish Water Treatment:
Most Brackish Water can be treated with a Reverse Osmosis Water Purification System, however, desalinating brackish water occurs at lower pressure compared to seawater desalination, resulting in more economical process, less energy consumption and more cost efficient.
Types of Reverse Osmosis by Water Quality:
1- Standard Reverse Osmosis (Salinity up to 2,000 ppm)
2- Brackish Reverse Osmosis (Salinity up to 10,000 ppm)
3- Seawater Reverse Osmosis (Salinity up to 45,000 ppm)
All Reverse Osmosis Systems require sufficient pre-treatment to ensure proper production, operation and to preserve its operational life. Pre-treatment process is engineered depending on feed water quality, water conditions and flow rates required.
Undersized pre-treatment process may cause a system overload, increasing the plant's internal parts damage and usage, requiring more service and maintenance which will interrupt normal operations more often, and this will reduce productivity and increase cost. Undersized pre-treatment will also increase scaling, fouling and plugging of the membrane elements which is the most expensive part of the reverse osmosis process.
The kind of pre-treatment system that is used greatly depends on feed water quality. Consequentially, sufficient feed water pre-treatment is dependent on:
· The source of the feed water
· The composition of the feed water
· The function of the feed water
We always require an exact water analysis report before we commence the manufacturing process of a reverse osmosis project in order to design and build a complete and a correct Reverse Osmosis system (http://ampac1.com/)