The growth of desalination plants worldwide is on the increase as global warming and local drought conditions continue. In all 7,500 desalination plants are currently operating worldwide with 60% of these situated in the Middle East. Unfortunately, many desalination plants are adversely affecting the environment.
Desalination removes dissolved minerals and salts from sea water, brackish water, or treated wastewater and has become an everyday accepted part of life in some countries. Without fresh water for drinking, irrigation and live stock they would simply cease to exist.
The most common processes used today are Reverse Osmosis(RO) and Distillation. Reverse osmosis removes dissolved salts through a porous membrane under high pressure, while distillation heats the water which is evaporated to separate out dissolved minerals.
Both reverse osmosis and distillation processes use harmful chemicals, produce waste and pollute their local environment. Cleaning agents such as chlorine, alkaline solutions, chemical disinfectants and crystal growth inhibitors are used to maintain their systems from cluggy build up.
Exhaust chimneys on many desalination plants belch harmful chemical clouds, and waste brine containing concentrated salt is produced and pumped back into waterways and coastal water. Local marine habitats face pressure with micro-organisms dying as salinity and water temperature increases.
Solutions to the environmental damage caused by harmful desalination plants include siting plants in areas with high volumes of brackish or salty groundwater which is more cost-effective than converting seawater. In addition, desalination plants are able to recover pure salt from their waste brine, which is then usable as raw material for chlorine, caustic soda, and hydrochloric acid.
New plants capable of extracting pure salt are being planned, yet with an existing 7,500 plants already discharging waste brine, it is imperative that future research include back porting technology for existing plants. With the growth of plants increasing worldwide, environmental concerns cannot be overlooked in our quest for more fresh water.