Improving Water by Removing Arsenic
By Marguerite Huber
If you lead an active and busy life like me, you probably don’t spend a lot of time thinking about what is in the water you drink. You just fill up your water bottle and are out the door.
But behind the scene a lot goes into making our water safe to drink. To protect public health, EPA regulates arsenic in drinking water. Arsenic is a semi-metal element that can enter drinking water supplies through natural deposits or from agricultural and industrial practices. Health effects due to prolonged excess exposure can include skin damage, circulatory system problems, and increased risk of cancer.
EPA initiated the Arsenic Removal Technology Demonstration Program to evaluate the performance, reliability, and cost of arsenic removal and the effect on water distribution systems. One type of arsenic removal system consists of a tank of adsorptive media that is similar to a home water softener.
As the water passes through the tank of media, the dissolved arsenic adsorbs on to surface of the media. Adsorption is not to be confused with absorption, which is the process in which a fluid is dissolved by a liquid or solid, such as water being absorbed by a sponge.
Adsorption on the other hand is the process in which atoms, ions or molecules, stick to a surface. Once the media reaches its arsenic removal capacity, the media must be replaced. Many water systems, such as the Twentynine Palms Water District in California, have experienced high operating costs due to frequent replacement of the adsorptive media.
EPA researchers partnered with Battelle to conduct lab and pilot studies to investigate the possibility of these media being reused to reduce costs. The study found that as much as 94% of the arsenic from exhausted media could be removed and the media could be regenerated.
Following the successful results of the laboratory regeneration study, EPA and Battelle demonstrated the efficiency of media regeneration in Twentynine Palms, CA. The testing led to substantial reductions in the operational cost, proving to be successful and that regeneration can work.
The goal of this research was to reduce operating costs, and since starting the regeneration program in 2010, Twentynine Palms Water district has been saving about $20,000 a year.
All in all, there is a lot of science and technology that bring you the clean water in your water bottle. I’m now going to stop and appreciate that each time I fill up my water bottle.
About the author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.
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