Meeting the new Canadian guideline for Manganese in drinking water

Meeting the new Canadian guideline for Manganese in drinking water

Greensand filtration vesselsGreensandPlus vessels for this Vancouver Island community on well water removes Iron, Manganese, Hydrogen Sulfide, Arsenic and Radium and recycles the backwash water.
Manganese is now a Canadian maximum acceptable concentration (MAC) and several British Columbia water utilities are looking for ways to address their well water with levels higher than 0.12 mg/L. If a utility can meet the aesthetic objective (AO) of 0.02 mg/L customers will be happier. Manganese causes a not pleasant looking brownish-black stain in consumer laundry, sinks, tubs, dishes, etc. Iron causes reddish-brown staining. Detergents don’t remove these stains, and the use of chlorine bleach and alkaline builders such as sodium carbonate can intensify the stains. Iron and manganese are chemically similar and often found together, and cause similar problems. Hydrogen sulfide – that rotten egg smell – is also often present. It is usually detected after potable water goes through a chemical change such as being heated in a hot water heater.

While the metals are still being studied for health issues, the black sticky mud like substance lining wells and reservoirs is a chronic headache for operators as it builds up over the years, plugging pipelines, tanks, water heaters and water softeners.

For BI Pure Water, high levels of manganese and iron in groundwater supply is the most common of water treatments. Manganese, iron, hydrogen sulfide and arsenic has been treated successfully for about 50 years with Greensand filters: the filters are easy to maintain and inexpensive. Ten years ago the manufacturer Inversand began selling the higher performing GreensandPlus which only needs chlorine to regenerate the media and we have used GreensandPlus in most of our systems. BI Pure Water is a Canadian distributor of GreensandPlus; if you can get it from a Canadian supplier it should be even lower cost.

Greensand and Manganese

Greensand particles have a large rough surface area and they attract soluble iron, manganese and sulfide compounds to the surface and retain them in the media bed. Silica Sand and chlorine can oxidize and filter like greensand but aren’t as efficient, requiring larger tanks.

As the oxidization happens these compounds/elements form the required precipitates and non-objectionable compounds — such as sulfide to sulfate. The sulfate is a soluble compound and passes through the filter. The iron and manganese form precipitates which are eventually backwashed from the filter.

The media is regenerated with chlorine either continuously or intermittently during a backwash process.

Manganese Treatment Case Studies

Brent Kennedy School near Castlegar will soon receive BI Pure Water’s Manganese Greensand system and chlorine injection. Three-quarters of the treated water is used to irrigate, one-quarter for potable water. A 1-3% chlorine solution is injected before a chlorine contact tank before the water entering four parallel vessels with Greensand to filter out the oxidants. The backwash of the Greensand occurs after hours: each of the vessels supplies water to the other as they go into backwash sequentially. We have proposed a detention cistern that would receive the backwash water which will then flow by gravity into the septic.

We have several Greensand systems in the Yukon. One will be delivered to a pre-built building with a truckfill on Kluane Lake called Burwash Landing.

In Teslin, Yukon the well source water is very difficult. It’s high in metals, as well as being hard, with Manganese close to 0.3 mg/L. Sodium is 12 mg/L, Chloride 24-27 mg/L, Arsenic 7-14.2 mg/L. Greensand also removes arsenic but will tend to remove iron, then manganese, then arsenic, so for capacity reasons there’s 3 additional filters with granular ferric hydroxide media for the arsenic. An additional RO unit was required to remove salts, dissolved organics, nitrates, residual inorganic chemicals and to effectively suppress microscopic parasites, bacteria and viruses.

A Greensand system for one of Powell River’s wells, has been performing according to spec, producing 234 m3/day.

Manganese Pilot Skid for Rent

Our pilot skids that consist of a GreensandPlus filter vessel, control panel for automatic operations, chlorine injection with a chlorine pump and chemical injector are being rented by the month and we have some available for municipal pilot testing. The space required by a pilot system is 2 feet wide x 4 feet long x 6 feet tall. Backwash tank if required: 48″ dia x 80″ tall. Power needed: 115 volt, single phase, 15 amp.

Contact us for more info, we’d like to help you with the most cost effective and efficient system for your Manganese issues.

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