The first World Water Day was held on March 22, 1993, when the United Nations General Assembly decided to celebrate the importance of freshwater. This year’s theme is ‘groundwater, making the invisible visible’.
Most people imagine the ocean when they think about desalination. However, the first reverse osmosis (RO) water treatment plant—built in Coalinga, California in 1965—was designed to desalinate brackish groundwater. There is a LOT of brackish groundwater across the United States, especially in locations that have limited freshwater supplies. The U.S. Geological Survey estimates that total brackish groundwater resources in the U.S. are 800 times the total amount of fresh groundwater pumped from all other sources every year. In line with this, NAWI Research Consortium Member Massachusetts Institute of Technology published an excellent assessment of the potential of brackish groundwater desalination in the country. Ocean desalination plants around the world currently produce more than 10 billion gallons of freshwater daily. In contrast, the total water production from brackish groundwater desalination facilities around the world is 2.3 billion gallons per day.
Brackish groundwater desalination has a number of advantages over ocean desalination:
- Brackish groundwater is often far less saline than ocean water, thus requiring less energy to remove the salt and enabling higher water recovery rates.
- It is geographically widespread and available as a resource for diverse communities (not just for those along the coast).
However, brackish groundwater is a challenging non-traditional water source to treat. Water is the “universal solvent”, and water that has remained underground for a long time can become saturated not only with highly soluble constituents (like salts) but also sparingly soluble constituents (such as silica and gypsum) that can precipitate out during the desalination process, “scaling” the interior surfaces of pipes and membranes. And, far from the seacoast, there are few options for economically disposing of the brine waste from the desalination process. Read more below as NAWI’s Research Director Dr. Meagan Mauter discusses the detailed baseline study conducted by NAWI researchers to assess the current technology approaches to treating this vast but challenging water supply.
NAWI has a number of research projects underway to tackle the many technical challenges that prevent wider use of brackish groundwater desalination.