Nov 30, 2006

Is Desalination Answer To Water

Despite the fact that desalination of seawater can provide needed freshwater to certain areas of the world, there are problems associated with it.

There are over 7,500 desalination plants in the world, converting billions, if not trillions of gallons of sea water.

60 percent of all the desalination plants are in the Middle East while 12% of desalinated water is produced in the Americas, including several plants in the Caribbean.

Despite the fact that desalination plants can produce fresh water, usually by reverse osmosis, there are some serious drawbacks to desalination.

  • Destruction of fish and crab larvae. It is estimated that one plant in California alone is responsible for killing 53 million fish larvae and 14 million crab larvae per year.
  • What to do with the brine? When seawater is desalinated, salty brine remains. Currently, this brine is being dumped into the sea, sent to wastewater plants, injected into saline aquifers, or injected into oil wells. But problems exist. Sinking brine plumes threaten sea life, particularly those at the lower end of the food chain. Injected, it runs the risk of polluting groundwater.
  • Toxic metals. The brine may also contain toxic metals which can also contaminate ground and surface water.
  • Chemicals used in defouling process. Desalination plants use chemicals to defoul, kill bacteria and algae that tend to grow in pipes and systems. These chemicals must be removed before the water is used as potable water, or water for irrigation.
  • Cost. The cost of water produced by desalination plants is significantly higher than that obtained from reservoirs or aquifers. In general, desalinated water costs anywhere from $700 per acre-foot to $6,000 per acre foot. Water from aquifers costs around $200 per acre-foot. Water in reservoir basins costs about $35 per acre-foot.