Research efforts pertaining to natural organic material (NOM) have focused primarily on the dissolved portion of NOM since it is the most prevalent fraction. Numerous procedures have been developed to separate dissolved organic material (DOM) into fractions but methods were not fully refined in the areas of quantitative analysis, DOM recovery, and DOM isolation.

This research chemically and physically characterized DOM using synthetic resin adsorption and ultrafiltration, respectively. A 0.45 μm filter separated the NOM into particulate and nonparticulate fractions prior to characterization. The DOM of two natural waters were fractionated into six separate organic fractions (hydrophobic bases, acids, neutrals and hydrophilic bases, acids, neutrals). Apparent molecular weight distributions were performed on the two natural waters and six organic fractions via ultrafiltration. The effects of pH on coagulation removal efficiency were investigated on four of the organic fractions (acidic and neutral). A procedure was developed to investigate the synergistic/antagonistic effects of the hydrophobic acid fraction and the hydrophobic neutral fraction on each other during coagulation. Ultrafilters (30K and 100K nominal molecular weight cutoff) were utilized to analyze the phase-change behavior of DOM during coagulation.

Results indicated the coagulation pH affected the removal of the organic acidic fractions but not the neutral fractions. A further study showed poorer removal of the hydrophobic neutral fraction resulting from the greater presence of the hydrophobic acid fraction in a solution composed of the two fractions and vice versa. At less than enhanced doses of both alum and ferric chloride there existed the presence of colloidal metal bound organic material. This colloidal fraction can be effectively removed by the addition of a nonionic polymer, providing a cost effective alternative to the higher coagulant doses often required to achieve enhanced coagulation of surface waters.