In late 2009, Water Works Engineers contacted AdEdge to design and implement an arsenic, iron and manganese removal system to serve the city of Aurora in Oregon. The existing water supply consisted of three wells feeding into a centralized distribution system with a maximum combined capacity of 500 gallons per minute (gpm).
At the time, the site had an arsenic level of 12 parts per billion (ppb), which is above the U.S. EPA’s maximum contaminant level (MCL) of 10 ppb. The city of Aurora also had iron and manganese levels of 0.9 mg/L and 0.189 mg/L, well above the secondary MCLs of 0.3 mg/L and 0.05 mg/L.
Arsenic, Iron and Manganese Removal
AdEdge worked closely with Water Works Engineers and Ashley Engineering to supply the treatment system, backwash recycle pump skid and components, chemical feed and instrumentation. AdEdge also furnished the system with a programmable logic controller (PLC) communications module to perform the automated functions needed for proper operation of the control valves.
The AdEdge treatment system featured a skid-mounted AD26 oxidation and filtration packaged unit sized for a maximum design flow rate of 500 gpm. The model, APU26-7260CS-3-AVH, utilizes AdEdge ADGS+ media in a three-vessel carbon steel configured in series. ADGS+ is a manganese dioxide coated silica media, which is NSF 61 certified and used for the removal of arsenic, iron and manganese. Chlorine is injected ahead of the treatment unit via a chemical feed module to oxidize arsenic (III) to arsenic (V) for optimized performance.
The system is equipped with automated control valves and harness, a central control panel with PLC and a color user interface screen. System features also include differential pressure switches, flow sensors and totalizers, and sample ports for a complete functioning packaged unit. Each 72-inch diameter treatment vessel contains approximately 84 cubic feet of AdEdge ADGS+ oxidation/filtration media. Backwashing of the systems occurs every three to four days based on the incoming levels of iron and manganese. Water exiting the treatment system feeds the 300,000 gallon storage tank and distributed to end users.
The system was started up and began operation in November 2010. Since the installation of the system, the arsenic, iron and manganese levels have been treated to below the treatment goals of 10 ppb, 0.3 mg/L, and 0.05 mg/L
Case Study Fast Facts
Client: City of Aurora
Engineers: Water Works Engineers, Ashley Engineering
Location: Aurora, OR
Date: November 2010
Contaminants treated: Arsenic, iron, manganese
Flow rate: 500 gpm