Manganese
Manganese
Manganese (Mn) is receiving increasing interest as a contaminant of concern in drinking water. It presents both health and aesthetic concerns at different concentrations. Although manganese is an essential nutrient, at higher concentrations it can have neurotoxic effects. At lower concentrations, it can discolor water and cause staining. Manganese in water does not have a noticeable taste.
About Manganese
Why is manganese of interest?
Manganese is an essential nutrient, but it can cause adverse cognitive and neurological effects, particularly in children, if consumed at too high of a concentration. It can also affect the aesthetic quality of drinking water, causing staining and discoloration. Manganese is present in both groundwaters and surface waters and is widely geographically distributed, so water systems across the U.S. should be aware of manganese and proactively manage it. It can accumulate in pipes in the distribution system over time, so systems likely need to manage manganese even after installing treatment to remove it.
What is its regulatory status?
- Health Canada — Maximum acceptable concentration of 0.12 mg/L and aesthetic object of 0.02 mg/L.
- The U.S. Environmental Protection Agency — Non-enforceable health advisory level of 0.3 mg/L for infants and 1.0 mg/L for the general population, and a non-enforceable secondary maximum contaminant level of 0.05 mg/L.
In the U.S., manganese was monitored from 2018-2020 as part of UCMR 4 and now is listed on the draft CCL 5 for potential regulation.
How can water systems manage manganese?
Managing manganese in drinking water can take place in the source water, at the treatment plant, and in the distribution system. For reservoirs, adjusting the intake level and adding mixing can lower the manganese concentration entering the plant. Primary treatment strategies for removing manganese at the plant are oxidation and particle separation, sorption to filter media, adsorptive contactor, and biological treatment. Manganese can slowly accumulate over time in the distribution system and deposits are more difficult to remove than iron, so more aggressive cleaning techniques like ice pigging or foam swabbing may be needed to remove manganese films.
Technical Resources
Manuals
AWWA Standards
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Events With a Focus on Manganese
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Related Resources
Iron and Manganese Removal Handbook
High levels of iron and manganese can cause adverse effects on water at the tap and subsequent customer dissatisfaction. This book addresses how to control and treat these contaminants.
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Full-Scale Implementation of Second-Stage Contactors for Manganese Removal
The use of post-filtration contactors for the removal of manganese (Mn) in the dissolved, reduced form (Mn2+ or Mn(II)) by sorption to manganese oxide–coated granular media and catalytic oxidation by free chlorine was implemented at the Lantern Hill Water Treatment Plant in Stonington, Conn., in order to lower disinfection by-product (DBP) formation while effectively controlling metals.
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Manganese: What Goes Around Comes Around
The complex chemistry of manganese makes optimizing its removal in surface water treatment plants challenging, particularly if a facility is zero-liquid discharge or if it recycles significant portions of its process washwater.
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Give Inorganic Contaminants the Respect They Deserve
Unlike some higher-profile contaminants utilities must deal with, inorganic contaminants don’t have long, unpronounceable names; they frequently occur naturally; and they have been a subject of concern in drinking water for many years.
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Adsorptive contractors for removal of soluble manganese during drinking water treatment
Water treatment facilities are often challenged to achieve effective soluble manganese (Mn) removal in the face of competing needs to achieve other water treatment objectives (e.g., disinfection by-product control and biological filtration). Previous research has demonstrated that effective soluble Mn removal can be achieved on media surfaces coated with manganese dioxide [MnOx(s)].
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Beware of Legacy Manganese Issues in Distribution Systems
Manganese (Mn) releases within water distribution systems aren’t always apparent, as in their effect on the aesthetic quality of water. Still, even without obvious visual signs, legacy Mn can present public health risks. Water utilities should develop a comprehensive Mn control strategy to safeguard water quality to the tap.
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Evaluate and Optimize Manganese Treatment
In light of increasing interest in water quality and health concerns related to manganese (Mn) at elevated levels, it’s important for water utilities to optimize existing treatment processes to enhance Mn control.
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Know The Benefits of Effective Manganese Management Strategies
The water industry is experiencing renewed interest in optimizing manganese (Mn) control. With greater knowledge of Mn in drinking water, water utilities will be better prepared to develop effective management strategies.
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External Resources
AWWA Policy Statements
AWWA’s policy statements are brief statements on protecting and improving water supply, water quality, management, and the interests of the public and the environment. They are written by consensus, subject to review and comment by AWWA committees, councils, and members. Because they represent AWWA’s position on these matters, they are approved by the AWWA Executive Committee of the board of directors.
Technical Committee Engagement
AWWA members are recognized globally for their industry expertise and their generosity in sharing that expertise for a better world through better water. AWWA members participate in committee activities, developing conference programs, writing technical manuals, developing standards, creating educational content and contributing to AWWA publications. Committee members primarily interact through conference calls, emails, and face to face meetings at conferences and events.
Inorganics Committee
Inorganic Contaminants Research Committee
Emerging Water Quality Issues Committee
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