Total organic halogen (TOX) is an analytically defined measurement that can provide an estimate of total organic bound halogen in water. The analysis of TOX in drinking water indicates that a large amount of the TOX formed during disinfection processes cannot be attributed to known specific disinfection byproducts. There has been a concern over the impact that the unknown fraction of TOX might have on human health. The standard TOX method cannot differentiate organic chlorine, bromine, and iodine. Ion chromatographic (IC) detection has been proposed for the halogen specific TOX analysis. The first objective of this research was to determine the optimum TOX protocol for use with IC detection to analyze total organic chlorine (TOCl), bromine (TOBr), and iodine (TOI). The pyrolytic analyzer using pure O 2 and off-line IC combined with a standard TOX carbon (coconut based) worked best for the differential TOX analysis. The second objective of this research was to assess the impact of bromide and iodide concentrations, different oxidation scenarios, and reaction conditions on the formation of unknown TOX. Chloramines and chlorine dioxide produced byproducts with a higher percentage of unknown TOX than free chlorine. Free chlorine formed more TOCl and TOBr than chloramines and chlorine dioxide in the presence of bromide. However, chloramines and chorine dioxide produced more TOI than chlorine and ozone in the presence of iodide. The third objective was to characterize unknown TOX precursors using resin (XAD-8, XAD-4) extraction and ultrafiltration methodologies. Hydrophobic and high molecular weight natural organic matter (NOM) was found to be a more important precursor for unknown TOX formation than hydrophilic and low molecular weight NOM. The forth objective was to determine the size and hydrophobicity of unknown TOX in drinking water. Total organic halogen from several finished waters was isolated using XAD resins and ultrafiltration membranes. A large fraction of the unknown TOX was comprised of hydrophilic compounds with high molecular weights. Ultrafiltration membranes were found to reject TOX compounds with molecular weights substantially below the membrane cutoffs. Neglecting this effect can lead to overestimation of the molecular size of TOX compounds.

Chemical characteristics and environmental behavior of halogenated organic (OX) compounds in biologically treated wastewater from a secondary-fiber mill were investigated. Liquid-liquid extraction techniques were developed and optimized for the identification and quantification of OX compounds from this sample matrix. Twenty OX compounds were identified in the treated wastewaters, accounting for 20 to 60 percent of the total organic halide in the wastewater. A significant fraction of the OX in the treated wastewater was accounted for by one single compound: 1,3-dichloro-2-propanol, which persisted through biological treatment. Much of the the organic matter in the wastewater. Volatilization was identified as a prominent transport process that affected the fate of a small fraction of the identified OX compounds. Photolysis was the only environmental transformation process that could effectively reduce trichlorophenol concentrations within the time-scales studied at this site. A significant portion of the OX was relatively stable under typical environmental conditions, resulting in its persistence in the receiving water body. Conventional biological treatment was not effective in reducing OX concentrations in the wastewater. Advanced processes like chemically assisted secondary clarification (with alum and ferric chloride) and dechlorination (with sulfite) did not have a significant effect on OX removal. Ozone oxidation and alkaline hydrolysis reduced OX concentrations in the effluent by over 50 percent.

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