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The Metropolitan Water District of Southern California initiated a study to evaluatemanganese (Mn) desorption from filter media during biological filtration start up. Mncontamination of the filter media was a byproduct of multiple years of pre-chlorinationwhile using Mn-containing ferric chloride (FeClsub3/sub) for coagulation. During pilot- and fullscaletesting, FeClsub3/sub coagulation (without chlorine) released soluble Mn at nearly fourtimes the level compared to alum (105 g/L for FeClsub3/sub and 27 g/L for alum). Pilot-scaleexperiments led to the conclusion that Mn was present in the filter column in threevalance states [Mn(II), Mn(III), and Mn(IV)]. Mn in the filter effluent was hypothesizedto be first physically displaced as Mn(III) from anthracite media by ferric iron,aluminum, and hydrogen, and then catalytically oxidized to Mn(IV) by silica sand. Includes 34 references, tables, figures.

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Edition: Vol. - No. Published: 11/01/2005 Number of Pages: 19File Size: 1 file , 610 KB