For the removal of iron from groundwater, aeration followed with rapid (sand) filtration is frequently applied. Iron removal in this process is achieved through oxidation of Fe2 + in aqueous solution followed by floc formation as well as adsorption of Fe2 + onto the filter media. The rate of oxidation of the adsorbed Fe2 + on the filter media plays an important role in this removal process. This study focuses on investigating the effect of pH on the rate of oxidation of adsorbed Fe2 + . Fe2 + has been adsorbed, under anoxic conditions, on iron oxide coated sand (IOCS) in a short filter column and subsequently oxidized by feeding the column with aerated water. Ferrous ions adsorbed at pH 5, 6, 7 and 8 demonstrated consumption of oxygen, when aerated water was fed into the column. The oxygen uptake at pH 7 and 8 was faster than at pH 5 and 6. However the difference was less pronounced than expected. The difference is attributed to the pH buffering effect of the IOCS. At feedwater pH 5, 6 and 7 the pH in the effluent was higher than in the influent, while a pH drop should occur because of oxidation of adsorbed Fe2 + . At pH 8, the pH dropped. These phenomena are attributed to the presence of calcium and /or ferrous carbonate in IOCS.
Research Article|November 01 2009
Oxidation of adsorbed ferrous iron: kinetics and influence of process conditions
1Department of Municipal Water and Infrastructure, UNESCO-IHE Institute for Water Education, P.O. Box 3015, 2601 DA, Delft, The Netherlands2Water Resources and Environmental Sanitation, Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
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Water Sci Technol (2009) 60 (9): 2353-2363.
R. Buamah, B. Petrusevski, J. C. Schippers; Oxidation of adsorbed ferrous iron: kinetics and influence of process conditions. Water Sci Technol 1 November 2009; 60 (9): 2353–2363. doi: https://doi.org/10.2166/wst.2009.597
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