Arsenic and Old… Media
There’s more than one way to remove Arsenic from water. Just like there’s more than one kind of Arsenic in the water. Arsenic is commonly found in different forms. For the sake of this Blog we will be discussing the most common types, Arsenite (As3), and Arsenate (As5). As3 is a smaller weaker Isotope of Arsenic than As5. However the As3 form is far worse for your health.
Because of it’s larger stronger size it is easier to remove As5 from the water. This can be done through Filtration, Anion Exchange, or Adsorption. The most common form of reduction used in Residential sites is Adsorption. Since the new Arsenic rule was released by the USEPA in 2006 there have been many new Media lines released with very little documentation regarding life expectancy. This is because Water quality is different from region to region. For more information on this subject please visit our website at www.secondwindwater.com.
Any time Secondwind solves for a Health concern we always recommend that redundancy be built into the system. If one system should stop working there should be a second, redundant, system in place to make the water safe. Therefore when we recommend Adsorption as a solution for Arsenic we usually are installing 2 tanks in series. When designing this system it is crucial to install a sampling port before the first Adsorber, at the mid point between Adsorbers, and after the second Adsorber. The 3 sampling ports are your life line to system diagnostics. The idea of having redundant tanks is that the first tank should offer ample contact time to adsorb all of the Arsenic, until the Media becomes exhausted. When the first Adsorber becomes exhausted As3, the smaller, weaker, and more harmful Isotope, will bleed through before the As5 does and so As3 will be the first to enter the fresh Second Adsorber. It is because of this that the Second Adsorber never last as long as the first.
Secondwind has been solving for Arsenic in water for many years. Our documentation indicates that it is most cost effective to replace the Arsenic media in the First Adsorber and switch the order of the tanks when the Mid Point samples reach 1/2 of the influent level. So if you have 30 ug/l coming in it would be most cost effective to exchange the Media when the Mid-point reaches 15 ug/l and then switch the order of the Adsorbers. If the lead Adsorber is not exchange with fresh Media at that point the Second Adsorber will become exhausted prematurely increasing the operation cost of the system. I will be writing more on this subject over the next few weeks.
Thank you for your continued support of Secondwind Water Systems. We truly appreciate your business and referrals. If you have any Water questions please visit our website at www.secondwindwater.com or call 1-800-287-5767. Until next time this is Chris Saltmarsh CWS-6, saying, “Thanks for reading!, and enjoy your great water”… : )
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