Water containing high levels of iron and manganese can be unpleasant both in taste and appearance often causing staining of baths, basins and clothes. Drinking water with elevated manganese levels can, in the long term, cause a manganese build-up in your system. Coftec has experience in addressing a variety of contaminants in drinking water, one of which is manganese.
Manganese has long been a difficult contaminant to remove during water treatment to bring it to the level for drinking water compliance. Difficulties are caused by different characteristics of manganese; soluble or insoluble, organically bound or inorganic. “Do not Consume” notices for drinking water sources are ever increasing in Ireland due to elevated manganese concentrations in the raw water sources, resulting in breaches of manganese in treated water. Elevated manganese in surface water sources is different to that from ground water sources and therefore should be treated differently.
Stratification of surface water into the epilimnion (upper layer) and hypolimnion (lower layer) results in different water characteristics such as DO & pH. In the epilimnion, radiation from the sun allows for photosynthesis resulting increased DO and pH. Under these conditions manganese is oxidised to insoluble forms which can be easily removed from the water by coagulation, clarification, and filtration.
In the hypolimnion layer, DO is depleted and bacteria obtain oxygen through Manganese ion reduction, thus releasing dissolved Mn+2 into the water. Molecules cannot diffuse back to the epilimnion due to different densities and properties (DO levels and pH) causing a cascading deterioration of water quality.
When the lake “turns-over” circulation begins, and the dissolved manganese is mixed throughout the water column. At this point elevated levels of soluble manganese is abstracted from the lake to the water treatment plant. This sudden elevated level of soluble manganese in the water treatment plant cannot be removed efficiently and results in a sudden spike of manganese in the treated water and at customer taps.
At Coftec, we understand the complexities and difficulties faced when dealing with manganese and other recalcitrant substances in raw and wastewater sources. Our multi-disciplinary team of scientists and engineers offer a proven track record of leveraging their expertise and experience in finding innovative and practical solutions to the problems such as excess levels of manganese faced at water treatment plants.
Contact Coftec whether designing a new facility or refurbishing, expanding or bringing an existing facility up to regulatory standards to discuss how we can help in your project.
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