While our company has been installing and maintaining water treatment equipment to remove elevated levels of manganese for more than 25 years, in the past several months the number of calls from prospective and existing customers about manganese has been at elevated levels. Some of these calls were instigated from letters sent from their towns with regard to manganese levels and potential health threats. The following excerpt from a letter to public water suppliers from the Massachusetts Department of Environmental Protection (MassDEP) regarding manganese monitoring helps to explain why many of these phone calls are being generated:
"As part of this outreach initiative on manganese, the MassDEP, in conjunction with the Massachusetts Department of Public Health, is sending out information on the U.S. EPA manganese health advisory to all health professionals overseeing the care of young children and pregnant women. As a result, you may receive phone calls from health professionals and customers inquiring as to the level of manganese in their drinking water. While many suppliers are not presently required to do so, some water suppliers have already provided MassDEP with baseline manganese sample results. To be ready to respond to questions on manganese, MassDEP strongly recommends that, if you have not already done so, you voluntarily collect manganese baseline samples now. For PWS with no manganese sampling results in the last twelve months, MassDEP will be adding mandatory baseline sampling for manganese to their sampling schedules for the 2014-2016 sampling period."
So, what is manganese, and where does it come from?
Manganese is a mineral that, in very small amounts, is essential for proper functioning of the human body. It is a trace mineral present in the human body in small quantities, primarily in the bones, liver, kidneys and pancreas. Manganese is important in connective tissues, in the formation of bones and blood-clotting factors, and is also involved in fat and carbohydrate metabolism, calcium absorption and blood sugar regulation. In addition, it is important for brain and nerve function.
There are two forms of manganese in the environment: Inorganic and organic compounds. Inorganic manganese compounds are used in the production of steel, batteries, ceramics and dietary supplements. These manganese compounds are also generated as combustion products from motor vehicles and coal-burning industrial plants. Organic manganese compounds are used in some pesticides, fertilizers and in a gasoline additive called Methylcyclopentadienyl manganese tricarbonyl (MMT). Manganese compounds can be present as dust particles in the air and dissolved in groundwater or drinking water.1
Manganese can enter into the human body through a variety of ways, including:
- Air: Manganese can be found in air but generally not at levels of concern for exposure. However, manganese and manganese compounds can be of higher concern near industries processing some of the products mentioned above.
- Water: Although not generally found at elevated levels in surface water, manganese is a common natural constituent of groundwater. Elevated concentrations of manganese may exist in some groundwater due to certain bedrock formations or pollution sources. In New England, manganese and iron are common partners in many water supplies, particularly in well water. Black deposits or dark stains in sinks, dishwashers and other fixtures are typical symptoms of elevated manganese levels.
- Diet: Manganese may be found in infant formulas and breast milk, leafy vegetables, some cereals, fruits and fruit juices. Elevated intake of manganese above recommended amounts may be of concern in some dietary situations.
Manganese toxicity potential
According to the U.S. Environmental Protection Agency (EPA), the World Health Organization (WHO) and the Agency for Toxic Substances and Disease Registry (ATSDR), manganese at very high levels can pose a neurotoxic risk.2 Exposure to high concentrations of manganese over the course of several years has been associated with toxicity to the nervous system, producing a syndrome that resembles Parkinsonism. This type of effect may be more likely to occur in the elderly.
Higher risks for children
Children are considered to be particularly susceptible to possible effects of high levels of manganese exposure because they absorb more and excrete less manganese than adults.3 This adds up to a greater potential for exposure in the very young. Since manganese’s effects on the developing nervous system have not been adequately studied, it is especially prudent for pregnant women and young children to have drinking water that is below the manganese action level (AL).4
ATSDR reports several studies that showed decreased ability in neurobehavioral performance testing and in several educational parameters in children exposed to high level of manganese in drinking water and diet for several years.
Current regulation of manganese
There are no enforceable federal drinking water standards for manganese. EPA has a secondary maximum contaminant level (SMCL) of 0.05 mg/l, which is intended to let the public know manganese can affect water quality at this level. This secondary standard is not health-based and is not enforceable. Although the aesthetic effects related to elevated manganese in drinking water are likely to be encountered at concentrations below the notification level, the notification level provides an extra layer of protection to consumers of water from systems subject to the SMCL requirements.
"Advisory levels" (versus ALs) for manganese have been established by EPA, which has a manganese health advisory level of 0.3 mg/l, and WHO, which has a manganese health guideline level of 0.4 mg/l.
In the absence of a federal actionable standard, some states have enacted their own actionable levels to further protect consumers. For example, the Connecticut Department of Public Health (DPH) recently set a drinking water AL for manganese of 0.5 mg/l to ensure protection against manganese toxicity. This AL is consistent with the WHO guidance level for manganese in drinking water. The California Division of Drinking Water has mandated a notification level for manganese at 0.5 mg/l. When manganese is present in water served to customers at concentrations greater than the notification level, certain requirements and recommendations apply.5
The notification level applies to all public water systems, whether or not they are covered by the current regulation of manganese. When manganese is present in concentrations greater than the notification level, the following requirements and recommendations apply: Systems with drinking water sources with manganese concentrations greater than the notification level are required to notify local city and county governing bodies, just as for other contaminants with notification levels and for contaminants that exceed MCLs.5
Consumer notification is recommended at levels greater than the notification level. This may be handled through the water systems’ annual consumer confidence reports. Other means could be used as well, if more appropriate, such as direct mailing or posting a notice. These should be coordinated with the local DDW district office.
Source removal is recommended at 10 times the notification level.
Effective removal of manganese from water
There are a several treatment methods available for the reduction of manganese. They include ion exchange, oxidation and filtration, reverse osmosis (RO) and distillation.
Ion exchange, oxidation and filtration are the most common technologies used for large-scale or point-of-entry (POE) manganese reduction. RO and distillation will effectively reduce manganese also, but they are most commonly deployed as point-of-use (POU) systems to produce high quality water for drinking and cooking only. High levels of manganese would be detrimental to both of these systems if they were deployed for use in large, POE-type volumes and, therefore, not recommended for this purpose.
The effects of water on manganese treatment selection
As with all prudent approaches to water filtration solutions, getting a water test to determine the characteristics of the water along with the type and amount of contaminants present is paramount to designing the proper water treatment solution. It is important not only to determine the level and type of manganese in the water, but also any other contaminants that may be present, as well as the characteristics of the water. These factors can affect which method of treatment will work best.
For example, ion exchange water softening is commonly used for the reduction of manganese in well water as it is normally found predominantly in solution or fully dissolved in well water. Manganese in solution is easily reduced with ion exchange. However, if you are working on a manganese problem in chlorinated city water, ion exchange may not be effective. The chlorine in the water would act as an oxidant, which would want to oxidize the manganese and convert it to a particulate you would need to filter out of the water. In this case, you would want to take advantage of the chlorine in the water and install an oxidation filtration system that would capitalize on the chlorine to enhance the functionality of the system.
Source water pH and the state of manganese
One point of caution: Years of experience have taught us that manganese can sometimes be difficult to remove. The pH of the water is one of the characteristics that will have to be considered when designing a manganese reduction system as it will impact the form of manganese you may be dealing with. For example, when the water’s pH is below 7.0, it will be difficult to oxidize. Manganese can either be found in solution, fully oxidized or sometimes partially oxidized in the water. If you are dealing with manganese in multiple states, a combination of treatment methods may be necessary to achieve the desired reduction of manganese.
Long-term, successful treatment
Once the proper system is installed, additional water tests should be performed to confirm proper system function just after installation. This should be followed by future, periodic water testing and proper maintenance as these are important to provide your customers with consistent, high quality water as well as maximum lifespan for the equipment you have recommended and installed.
Sources
- U.S. Centers for Disease Control and Prevention (ATSDR). 2000. “Toxicological Profile for Manganese.” http://www.atsdr.cdc.gov/toxprofiles/tp151.html.
- ATSDR (2), 2008; U.S. EPA, 1996, 2003, 2004; WHO, 2004).
- ATSDR (2), 2008; U.S. EPA, 1996.
- Connecticut Department of Public Health, Drinking Water Section
- California Environmental Protection Agency, State Water Resources Control Board
Mark St. Hilaire of Atlas Watersystems, Inc.
