Reducing arsenic levels

Dec. 5, 2007

Wells J-12 and J-13 are located in Area 25 of the Nevada Test Site near Mercury, Nev. These wells supply potable water for the Yucca Mountain Project. Water quality analyses revealed that arsenic concentrations exceeded the new maximum contaminant level (MCL). Before choosing a technology to reduce it, the site manager, Bechtel SAIC, contracted with Dr. Dennis A. Clifford at the University of Houston and a team of consultants to review various treatment technologies for reducing the arsenic concentrations to acceptable levels.

Dr. Clifford and Los Alamos Technical Associates recommended using granular ferric oxide technology for the treatment system. AdEdge was subsequently selected and awarded the project. AdEdge assisted Bechtel-SAIC with obtaining Nevada DEP regulatory approvals that would allow the system to be installed.

It is one of the first arsenic treatment installations that the DEP has permitted in the state of Nevada.

The AdEdge arsenic treatment system consists a skid-mounted adsorption package unit sized to accommodate a maximum design flow rate of 80 gpm. The model APU-80CSLL utilizes a twin vessel carbon steel vessel configuration for arsenic removal in a series (lead/lag). The system is equipped with automated control valves and harness, a central control panel with programmable logic controller and a color user interface screen. System features also include differential pressure switches; control panel and local gauges; flow sensors and totalizers; and a central hydraulic panel with sample ports for a complete functioning packaged unit.

Groundwater is pumped from the two wells through a 20,000-gal storage tank. From the storage tank, groundwater is chlorinated and flows through another atmospheric water storage tank prior to treatment. The 48-in. diameter APU vessels each contain approximately 37 cu ft of Bayoxide E33 adsorption media.

The media has been in commercial use since 1999, serving nearly two million customers, and has been deployed in over 60 public water installations in the U.S., Canada and Mexico since 2002. AdEdge's packaged solutions, utilizing granular ferric oxide media, have applications for small community water systems, schools and mobile home parks. They have also been used in more than 1,500 private residential applications.

The 80-gpm Yucca Mountain system was deployed in early January 2006 and began full-scale operations, treating approximately 5,000 gpd. Effluent samples, taken at the time of startup and subsequently, have indicated the removal of arsenic to nondetectable level—well below the new arsenic treatment standard of 10 ppb. To date, AdEdge has also received NDEP approvals and deployed an arsenic treatment system at the Tonopah Test Range and will be deploying two additional packaged systems for Newmont Mining in Nevada.

About the Author

Greg Gilles