Reducing Arsenic at a U.S. Navy Facility

In late 2006, AdEdge Technologies was awarded a turnkey adsorption-based system for arsenic removal for the Naval Air Station Electronic Warfare Range (EWR) Centroid Facility in Fallon, Nev. AdEdge performed this turnkey contract under a task order from Barajas & Associates and U.S. Naval Facilities Engineering Command (NAVFAC) oversight.

The Nevada Department of Environmental Protection (NVDEP) approved engineering plans and the permit application. Extensive coordination was executed with the base, NAVFAC, BAI and other parties. Construction began in April 2007 to install the packaged adsorption system inside the existing facility.

The APU is designed to treat the flow from the single existing groundwater well, which directly feeds the system before entering a 300,000-gal above-ground storage tank. The system features a twin-vessel, parallel configuration that uses Bayoxide E33 adsorption media , an alternative for arsenic removal permitted by NVDEP at multiple locations in Nevada and throughout the U.S. The system also includes a control panel, differential pressure gauges, inlet and outlet pressure gauges and stainless steel sample ports for easy operation and monitoring.

The AdEdge APU-100CS-U-2-MVH arsenic treatment system features a model modular adsorption package unit (APU) system designed for 100-gal-per-minute flow at 60 psi. The system was modularized for easy placement through the available doorway near the former fuel tank storage area.

Prior to entering the system, the raw water is chlorinated with sodium hypochlorite. The system has the granular ferric oxide media loaded into the two vessels operating in parallel. The media is simple to use in conventional adsorption vessels, has a very long life before replacement, does not impart any harmful residuals or odor and is certified by NSF International for use in drinking water applications.

Each vessel is equipped with a 5-valve piping harness. To keep costs down, piping, internals and distributors on the units were SCH 80 PVC. Subsequent to the installation, a complete backwash recycle system was requested by the U.S. Navy and designed and installed by AdEdge . This additional equipment enables particulate filtration and 100% recycle of the periodic backwash water from the unit.

Since operations began in April 2007, the system has consistently met all the EPA maximum contaminant levels for arsenic and discharge criteria removing arsenic from approximately 28 parts per billion (ppb) to less than 2 ppb. The site uses approximately 40,000 gal per week. The system is sampled and monitored by a local certified operator contracted by the base. The system has operated thus far with 100% online time and minimal operator attention.