Factors Affecting The Removal Of Iron And Manganese From Ground Water

This research study describes the chemistry and suggested treatment of manganese in drinking water, with the goals of reducing customer complaints and improving perceived water quality. The problems are aesthetic-water discoloration (usually black or dark red), clothing and fixture staining, turbid water sediments, and, at very high levels, metallic taste.

The presence of iron and manganese in drinking water are generally not hazardous to health. However, there are few things are more alarming to customers than seeing red water or black water come out of their faucets. This book offers an analysis of current and emerging methods for iron and manganese removal as well as guidance for handling residuals. Using firsthand field experience and detailed case studies, the authors explain the processes to follow.

This Best Practice Guide on the Control of Iron and Manganese in Water Supply is one of a series produced by the International Water Association’s Specialist Group on Metals and Related Substances in Drinking Water. Iron and manganese are often found in soft upland water sources associated with natural organic matter and are also commonly found in the groundwater abstracted from confined and unconfined aquifers. The presence of iron and manganese in water is one of the most frequent reasons for customers’ complaint due to aesthetic issues (yellow, brown and black or stains on laundry and plumbing fixtures). These two metals can be removed fairly readily by physico-chemical treatment. The municipal treatment systems deployed derive benefit from their larger scale, particularly in relation to control, but the processes used are less suitable for the numerous small supplies that are the most common water supplies throughout Europe, especially in rural areas. One important source of iron in drinking water is from old corroded cast-iron water mains, historically the material used most commonly in supply networks. Replacement and refurbishment is very expensive and the major challenge is how best to prioritize available expenditure. The purpose for this Best Practice Guide on the Control of Iron and Manganese in Water Supply is to give readers the broad view of a problem based on state-of-the-art compilation of the range of scientific, engineering, regulatory and operational issues concerned with the control of iron and manganese in drinking water. The Guide is of interest to water utility practitioners, health agencies and policy makers, as well as students on civil engineering and environmental engineering courses. Authors: Dr Adam Postawa, AGH University of Science and Technology, Faculty of Geology, Geophysics and Environment Protection, Krakow, Poland and Dr Colin R Hayes, University of Swansea, UK, Chair of IWA Specialist Group on Metals and Related Substances in Drinking Water.

Dissolved trace elements, including iron and manganese, are often an important factor in use of ground water for drinking-water supplies. Concentrations of these trace elements can very over several orders of magnitude across local well networks as well as across regions of the United States.

In The Netherlands, Belgium and other European countries, manganese is removed by conventional groundwater treatment with aeration and rapid (sand) filtration. Such a treatment process is easy to operate, cost effective and sustainable, because it does not make use of strong oxidants such as O3, Cl2, ClO2 and KMnO4 with the associated risk of by-product formation and over or under dosing. However, application of aeration-filtration is also facing drawbacks, especially the long ripening time of filter media. Due to the long ripening time, water companies have to waste large volumes of treated water, making this process less sustainable. Also, costs associated with filter media ripening (man power, electricity, operational and analysis costs) are high. Therefore decreasing the filter ripening time, regarding manganese removal is a big issue. Although already extended research has been carried out into manganese removal, the controlling mechanisms, especially of the start up face of filter media ripening, are not fully understood yet. The emphasis of this thesis is to provide a better understanding of the mechanisms involved in the ripening of virgin filter media, regarding manganese removal and how to shorten or completely eliminate the long ripening period of filters with virgin material. This thesis therefore highlights the role of the formation of a manganese oxide coating on virgin filter media. Characterization and identification revealed that the responsible manganese oxide for an effective manganese removal was Birnessite. It was found that Birnessite, formed at the beginning of the ripening process was of a biological origin. Based on the knowledge that manganese removal in conventional groundwater treatment is initiated biologically, long ripening times may be reduced by creating conditions favouring the growth of manganese oxidizing bacteria, e.g., by limiting the back wash frequency and / or intensity. Additionally, this thesis also shows that the use of freshly prepared manganese oxide, containing Birnessite, can completely eliminate filter media ripening time.