Q&A: Selecting and Maintaining an Arsenic Treatment System

Learn more about what parameters should be considered when choosing and operating an arsenic removal system

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Q&A: Selecting and Maintaining an Arsenic Treatment System

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This Q&A continues the discussion of arsenic treatment options with AdEdge Water Technologies.

How does E33 get disposed of?
One of the key advantages of granular ferric oxide adsorbent is its ability to strongly bind arsenic as water passes through the media through a combination of adsorption, adhesion and other physical/chemical mechanisms. The spent adsorption media easily passes the U.S. EPA’s Toxic Characteristic Leaching Procedure threshold. The TCLP test is an extraction procedure used for determining whether the media, when discarded, would classify as a hazardous waste.

How long does E33 last and what do you do when its exhausted?
AdEdge has a predictive model for all treatment approaches that gives the expected life of the media. When the water chemistry is fully reported, none of AdEdge’s treatment systems has underperformed in media life. Media life depends on total gallons through the system and the water quality. Once the media is exhausted, a vac truck will remove the spent media from the treatment system and new media will be funneled into the vessels.

What parameters must be considered when choosing an arsenic removal system?
When designing an APU33 arsenic removal system for a small water system application, it is always recommended to obtain sizing information from AdEdge Water Technologies; however, water quality and hydraulics are important design parameters when undertaking design of an APU33 arsenic removal system. Water quality parameters to consider include: arsenic concentration, pH, phosphate concentration, silica concentration, iron and manganese concentration, vanadium, sulfide and other heavy metals.

What is empty bed contact time?
Empty bed contact time is the time it would take water to fill a volume equivalent to the media bed. It essentially ignores the actual volume of the media and so the calculated EBCT is greater than the actual contact time. The EBCT required is set by the reaction kinetics of the adsorption process and for simple waters is generally three to four minutes. For more complex waters an EBCT of 5 minutes or more is recommended.

Why do you backwash the media? How often do you backwash the media?
It is recommended that periodic backwashing or “fluffing” of the media is performed every one to three months depending on the usage and water quality. It is performed for two reasons. All media in pressurized systems over time can compact and potentially develop preferential channels that can cause short-circuiting or incomplete adsorption. Additionally, sediment from the well, oxidized iron precipitate from the feed water, or other suspended material may be retained and captured in the media bed. To prevent excessive pressure drop or channeling, backwashing to lift or fluff the media is best performed periodically.

What options do homeowners have to treat their homes?
Homeowners have a couple options to treat arsenic in their homes. A point of use system is an under-the-counter treatment system that has a cartridge made of E33 and a carbon block. A point of entry system is another treatment option. Point of entry systems treat the entire house and contain AdEdge’s Bayoxide E33 arsenic removal media.

About AdEdge Water Technologies
Headquartered just north of Atlanta, Georgia, AdEdge Water Technologies specializes in the design, development, manufacturing and supply of innovative water treatment solutions that remove contaminants from process or aqueous streams. AdEdge offers a full range of conventional and innovative treatment technologies to achieve trough standards including adsorption, coagulation, ion exchange, biofiltration and membrane-based solutions. For more information, call 866/8ADEDGE or visit www.adedgetechnologies.com.


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