The influence of solution pH, DOC concentration, the relative molecular weight distribution of DOC, and the source of DOC were investigated for their effects on the removal of complexed Fe(II) by alum coagulation and/or KMn04 and H20 2 oxidation. The differentiation between particulate, colloidal, and soluble iron species was achieved through the use of 0.2 urn filters and 100K ultrafilters.

Results from oxidation and ultrafiltration studies indicated incomplete complexation of the Fe(II) by DOC in solution. Following the addition of either oxidant, uncomplexed Fe(II) was oxidized to Fe (III) which was either complexed by high molecular weight DOC or formed colloidal iron oxides, both of which were efficiently removed by alum coagulation. Alum coagulation alone, however, was ineffective for removing Fe(II) in the presence of DOC.

Results revealed the formation of particulate iron species to be a function of DOC source. The formation of colloidal iron was dependent upon DOC concentration and DOC source. The adsorption of DOC by iron oxides was observed to accompany the formation of colloidal iron species.