Formation and Control of Trihalomethanes in Chlorinated Drinking Waters Containing Fulvic Acid

摘要

The formation of halogenated organic compounds in drinking waters is a potentially serious environmental problem. This study examined the production of trihalomethanes by the chlorination of drinking waters containing fulvic acid and the effects of conventional water treatment processes on this phenomenon. Initially, fulvic acid was further fractionated into four subfractions by column chromatographic techniques. Chemical analysis via C-H-N-O elemental analysis, infrared spectroscopy, and nuclear magnetic resonance spectroscopy was employed to gain information on functional group content and distribution. The chlorination of fulvic acid fractions confirmed that fulvic acid compounds are significant precursors to trihalomethane formation and indicated that a number of chemical structures and functional groups is involved in the haloform reaction. The removal of fulvic acid in coagulation processes and its relationship to trihalomethane formation upon subsequent chlorination were studied in controlled experiments. Results indicated that coagulation does not uniformly remove all fulvic acid compounds. Evidence suggests that low molecular weight aromatic compounds are poorly removed by coagulation processes. In addition, studies demonstrated that the chloroform yield of fulvic acid compounds decreased significantly following coagulation.