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Monthly Archives: May 2011

  • Rising Salinity Cause for Concern at North Carolina Desalination Plant

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    An increase in salinity levels at the North Reverse Osmosis Water Plant in Kill Devil Hills (yes, that’s the town name) that had been creating stress for some local officials has been explained in a recent study. Researchers from nearby Duke University found that the rising salinity levels at this coastal aquifer are the result of fossil seawater and not seawater intrusion, as had been feared. Since the well’s installation in the late 1980’s salinity has more than doubled from about 1,000 mg/L to about 2,500 mg/L. There was much cause for relief however, when researchers were able to attribute the rise to fossilized seawater and not to seawater leaking in from the coast.

    According to the director of the study, Duke Professor Avner Vengosh, knowing the source of the salinity increase is important because fossil seawater raises salinity, “At a relatively slow and steady rate that is more manageable and sustainable than the rapid increase we’d see if there was modern-day seawater intrusion.” As a result of this study the community will be able to rely on this aquifer for decades to come without having to resort to more expensive seawater desalination techniques which require more energy and advanced filtration methods.

    Current treatment for groundwater desalination includes the use of reverse osmosis (RO) membranes to separate dissolved salts from potable water. Even with the rising salinity level these membranes remove around 96 to 99 percent of the dissolved salts. RO membranes also remove between 16 and 42 percent of the boron and 54 to 75 percent of the arsenic from the groundwater. Additional treatment following reverse osmosis desalination continues to remove arsenic until it is within safe drinking levels (10 parts per billion, according to the EPA).

    Because seawater consistently has more salt than groundwater it requires more energy to treat, and therefore the cost is higher. Per this report on desalination from the Pacific Institute, “Energy is the single largest variable cost for a desalination plant, varying from one-third to more than one-half the cost of produced water.” The report also states, “At these percentages, a 25% increase in energy cost would increase the cost of produced water by 11% (for RO plants).” In looking at these percentages, it’s easy to see why the plant was concerned about seawater intrusion. Thanks to this research, the local citizens can drink easier knowing they have a supply of healthy, affordable water for a long time to come.

    Click here to learn more about this case.

    This post was posted in Water and Fluid Separation News and was tagged with Water and Wastewater Treatment, Environmental Lab, Water Treatment, Reverse Osmosis, EPA, Brakish Water

  • Kids Today

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    If you haven’t taken a look at the semifinalists for the Google Science Fair you still have a few days left to view the submissions and cast your votes! At stake is a $50,000 scholarship from Google, along with an opportunity to apprentice with Google or one of their partner organizations. There are 60 very interesting entries spread across three categories and covering just about every discipline of science. Suffice to say that the projects went beyond the paper-mache volcano. Some examples include:

    Impressive stuff indeed! Especially considering all of these submissions came from 13-18 year-olds, a time when a lot of us were just trying to get a grasp on puberty. Kudos to Google and their partners for this project: CERN, the LEGO Group, National Geographic, and Scientific American. And of course, best of luck to all the entrants! Surely there are some incredibly proud parents, teachers, and mentors behind them.

    This post was posted in Company News and was tagged with General Science, Off Topic

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