Manganese is a naturally occurring mineral deposited from sediment and rocks. When present in high levels, manganese affects the taste of water and can cause staining on pipes and plumbing fixtures, as well as toxicity to plant life. To limit its effects, the U.S. Environmental Protection Agency’s (EPA’s) maximum contaminant level (MCL) for manganese is 0.05 mg/L. Here is how three municipalities used AdEdge Water Technologies solutions to reduce manganese (and co-occurring iron) in their water.
1. World War II Memorial – Washington, D.C.
The World War II Memorial sprawls across 7.4 acres on the National Mall in Washington, D.C. It is comprised of 56, 17-ft granite pillars and two, 43-ft pavilions that surround a plaza with a rainbow pool. During its construction in 2003, Walsh Construction contracted AdEdge to develop a treatment system for shallow groundwater collected by subsurface drainage. High levels of manganese, iron and arsenic in the groundwater needed to be treated before being discharged into the Potomac River.
AdEdge’s treatment solution consisted of two AD26 parallel, skid-mounted oxidation/filtration (O/F) systems rated for 30 gpm. Raw water is pretreated with hypochlorite before it reaches the filtration systems, which are located 20 feet below the memorial in a secured concrete vault. The systems then oxidize and filter manganese and iron using a proprietary, NSF 61-certified, granular ferric oxide media. When the media is spent, it is discarded as a non-hazardous solid waste.
The system went into operation in June 2004 and is currently being operated by the National Park Service.
2. City of Roswell – Roswell, Ga.
In December 2012, AdEdge was tasked with developing a manganese and iron removal system for a new water treatment facility that would service about 90,000 residents in Roswell, Ga. At >0.1 mg/L and >0.8 mg/L respectively, the raw water had manganese and iron levels well above EPA standards.
To treat the water supply wells, AdEdge designed a 400-gpm, compact, skid-mounted unit that utilizes its GS+ coagulation/filtration (C/F) media. Raw water is pretreated with sodium hypochlorite to oxidize iron and manganese for optimal removal once it enters the two, 72-inch diameter carbon steel vessels within the treatment system. The system also has inline turbidity, pH, and chlorine influent and effluent monitoring equipment, as well as differential pressure monitoring, local pressure gauges, flow sensors and a central hydraulic panel.
The system (pictured) has consistently met effluent treatment goals for manganese and iron since it was commissioned in late 2012.
3. Worthington Hills Neighborhood – Worthington Hills, Ohio
The following year, in August 2013, AdEdge was contacted for a project about 600 miles north of Roswell, Ga., in the Worthington Hills neighborhood outside of Columbus. Aqua Ohio, the water utility serving the area, contracted AdEdge to design, manufacture and start a manganese and iron removal system. Worthington Hills had a manganese concentration of 0.30 mg/L and an iron concentration that fluctuated between 1.8 mg/L and 2.0 mg/L.
AdEdge deployed a 625-gpm, AD26 O/F system to treat and remove manganese and iron. Similar to the systems in Washington, D.C., and Roswell, Ga., raw water is injected with sodium hypochlorite prior to entering the treatment system, where a manganese dioxide media removes manganese and iron. Backwashing of the treatment vessels occurs approximately every two to three days.
Since the treatment system began operation in August 2013, iron and manganese levels have lowered to below the EPA MCLs.