While much of the discussion of “new water” in the western United States involves desalination of seawater, there’s an experiment getting underway outside Albuquerque that is part of a new approach to the problem: desalination of brackish groundwater. My colleague Rosalie Rayburn has a story in the Albuquerque Journal on the latest testing going on here, out in Sandoval County on the northwest edge of the Albuquerque metro area:
The water is in a briny aquifer more than 3,500 feet below the Rio Puerco basin. A county drilling project discovered the aquifer in 2007. Testing last year indicated it is big enough to support a community of 300,000 people for 100 years. The water contains dissolved solids that must be removed before it is suitable for domestic use.
The technology is largely the same as used for seawater desal, generally reverse osmosis. But the difference in water sources raises a couple of problems that make inland desal quite different from ocean desal.
First, the ocean is, for all practical purposes, a sustainable water source. There are other sustainability issues, involving energy use, but you’re essentially never going to run out of ocean water. Inland desal depends on reservoirs of ancient water that will be mined if this process goes forward in a big way. So, like any groundwater mining, it’s not sustainable in the long term.
Second, you’ve got an enormous waste disposal problem. Roughly speaking, for every three gallons or so of clean water you get the residual brines concentrated in a fourth gallon. You’ve got to get rid of that somehow.
And of course the whole process – ocean or inland – is quite energy intensive.
For more, see what El Paso, Texas is doing.