Laboratory investigation of deferrization processes of ground water using physico-chemical method

S.Stasyuk

Keywords: ground water, water deferrization, simplified aeration of water, pinot-polystyrene media, upward water filtration, pollution-holding capacity, filtration cycle duration, intensity and duration of rinsing

 Reagent and non-reagent methods are used to remove iron from water, the selection of which depends on the amount and form of iron, the qualitative composition of water and the efficiency of the water treatment plant. The Institute for Water Problems and Land Reclamation of NAAS has developed and patented a plant  for iron removal and water softening, which can remove impurities that are most commonly found in underground waters from water using reagent or non-reagent methods. The processes of underground water deferrization using physical and chemical method were investigated at such plant in order to determine the patterns of changing the iron content in filtered water during the filtracycle at three constant filtration rates: 7; 9 and 11 m/h. Iron oxidation was carried out directly in the water-tank of the plant using the method of simplified aeration.

During water aeration, the oxidation of divalent iron was carried out with its transformation into a trivalent form and the formation of slightly soluble iron oxide Fe (OH)3, which was deposited in the precipitate, and a carbon dioxide CO2, which was removed from water. Iron oxidation can be carried out in two ways: the physico-chemical used in this work, in which the reaction occurred directly in the water-tank of the laboratory plant; and biological, in which the specific iron bacteria in the fibrous media of water tank intensively oxidize bivalent iron, consuming the oxidation energy for their life. The maximum filtration duration was determined by the time of water filtration, after which the contact clarifying filter should be flushed, as the quality of the filtered water reached the maximum permissible values ​​of the iron content controlled by the corresponding limiting head loss at the contact clarifying filter. According to the results of laboratory investigations of the processes of deferrization of groundwater applying their simplified aeration and upward filtering through floating pinot-polystyrene media, the patterns of changes in the iron content in filtered water during the filtration cycle at different rates of water filtration were established and recommendations for optimal modes of operation of water treatment facilities were developed.

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