Chlorination and Coagulation of Humic and Fulvic Acids

Drinking waters have recently been found to contain potentially harmful concentrations of chloroform and other trihalomethanes. Rook1 2 has shown that chloroform is formed from the reaction of chlorine with humic substances in natural waters. These substances originate from vegetative decay and make up a significant portion of the total organic carbon content of natural waters. Humic acids and fulvic acids, which together constitute over 80 percent by weight of all natural aquatic organic material, can be coagulated by aluminum and iron(III) salts.3 5 The humic acids (the alkaline-soluble, acid-insoluble fraction) have a higher molecular weight and are more readily coagulated than the fulvic acids (alkaline-soluble and acid-soluble fraction). The extent to which chlorine reacts with humic and fulvic acids has not been