The effect of different oxidation and filtration processes on the molecular size distribution of humic material

The effect of different oxidation and filtration processes on the amount and character of organic matter in drinking water was studied. TOC, KMnO₄ value, colour and fractions of humic material were analyzed from bank filtrated lake water, chemically coagulated and sand filtrated water, ozonated, O₃/H₂O₂ treated, chlorinated, granular activated carbon (GAC) filtrated and nanofiltrated water. Size exclusion chromatography was used to separate different fractions of humic molecules. Six different fractions were found from bank filtrated lake water and from chemically coagulated and sand filtrated water. The molecular weight of humic fractions ranged from about 1000 (the last fraction) to about 100 000 dalton (the first fraction). Most of the humic molecules of bank filtrated lake water were found in the third and fourth fractions. After the oxidation and filtration processes the first fraction of humic molecules disappeared completely and the fourth and fifth fractions dominated. The total sum of the humic fractions was most effectively reduced after the O₃/H₂O₂ treatment, by about 70%.