In November 2009, AdEdge Water Technologies LLC was contacted by Great West Eng. to provide an arsenic and iron removal system for the Gore Hill County water treatment plant wells in Great Falls, Mont. The existing water system consisted of multiple wells feeding into a centralized distribution system with a maximum capacity of 150 gal per minute (gpm).
The raw water for the first plant has an average arsenic level of 18 ppb and an iron level of 1.39 mg/L, well above the U.S. Environmental Protection Agency (EPA) maximum contaminant levels (MCLs) of 10 ppb and 0.3 mg/L. The second plant has an average arsenic level of 21 ppb and an average iron level of 4.51 mg/L, also well above the EPA MCLs.
Finding a Treatment Solution
AdEdge designed and manufactured a skid-mounted AD26 oxidation and filtration package unit sized for a maximum design flow of 150 gpm. The first plant features the model APU26-4260CS-2-AVH and utilizes the oxidation media in a two-vessel configuration. The second plant features the model APU26-4260CS-3-AVH and utilizes the oxidation media in a three-vessel configuration.
Each system is equipped with automated control valves and harness, an INGenius 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.
A continuous feed of sodium hypochlorite is fed prior to the treatment system to optimize the removal of arsenic and iron. Each 42-in.-diameter treatment vessel contains 28 cu ft of the oxidation and filtration media.
A Worthwhile Investment
In addition to the arsenic and iron treatment systems, AdEdge integrated an H2Zero backwash and recycle system for each site. The system reclaims 100% of the backwash wastewater and removes the captured arsenic and iron as a semi-solid sludge that can be disposed of in a non-hazardous landfill.
Backwashing of the treatment systems occurs two or three times a week, depending on the incoming levels of iron and water usage.
The system began operations in April 2011. Since then, iron and arsenic levels are at non-detectable levels.
Richard Cavagnaro Jr. can be reached at [email protected].
