engleski

Simultaneous Biological Removal Of Iron, Manganese And Ammonium From The Raw Water

High concentrations of iron, manganese and ammonia in groundwater have undesirable influence on water quality in distribution system. Thus, a simple and efficient treatment procedure is needed. The simultaneous biological removal of iron, manganese and ammonia in rapid sand filters seems to have increasing importance and become as procedure of choice at many sites. Unfortunately, problems my appear mainly caused by non proper design parameters of the treatment plants, neglecting the basic chemical and biological removal processes and their dependence on the composition of raw water. Investigations were carried out to define the basic removal processes of Fe2+, Mn2+ and NH4+ from the ground water. The chemically and biologically adapted, over ten years in operation, deep-bed sand filter mass of the treatment plant Ravnik (Croatia) was used for the experiments. Samples of silica sand particles from filter have been taken to demonstrate and identify the microorganisms capable to oxidize metal ions and ammonia present in the raw water. By direct microscopic examination and culturing in enrichment and selective media, several bacteria were isolated and identified in the immobilized layer of biomass covering the surface of the sand particles. Among them dominated bacteria belonging to the genus Siderocapsa that can oxidize Fe2+ and Mn2+ and nitrifying bacteria belonging to the genera Nitrosomonas and Nitrobacter. Moreover, the oxidation rate of Fe2+, Mn2+ and NH4+ in the presence of the isolated bacteria was determined under different laboratory conditions and reaction mechanisms of their simultaneous removal from ground water has been proposed

ammonium; biofiltration; groundwater; iron; manganese

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