Alfred D. Thruston

Identification of new drinking water disinfection by-products from ozone, chlorine dioxide, chloramine, and chlorine.

Many drinking water treatment plants are currently using alternative disinfectants to treat drinking water, with ozone, chlorine dioxide, and chloramine being the most popular. However, compared to chlorine, which has been much more widely studied, there is little information about the disinfection by-products (DBPs) that these alternative disinfectants produce. Thus, it is not known if the DBPs from alternative disinfectants are safer or more hazardous than those formed by chlorine. To answer this question, we have set out to comprehensively identify DBPs formed by these alternative disinfectants, as well as by chlorine. The results presented here represent a compilation of the last 8 years of our research in identifying new DBPs from ozone, chlorine dioxide, chloramine, and chlorine. We also include results from recent studies of Israel drinking water disinfected with both chlorine dioxide and chloramine. Over 200 DBPs were identified, many of which have never been reported. In comparing by-products formed by the different disinfectants, ozone, chlorine dioxide, and chloramine formed fewer halogenated DBPs than chlorine.

Multispectral identification of chlorine dioxide disinfection byproducts in drinking water

This paper discusses the identification of organic disinfection byproducts (DBPs) at a pilot plant in Evansville, IN, which uses chlorine dioxide as a primary disinfectant. Unconventioal multispectral identification techniques (gas chromatograpby combined with high- and low-resolution electron-impact mass spectrometry, low-resolution chernical ionization mass spectrometry, and Fourier transform infrared spectroscopy) were used to identify more than 40 DBPs in finished water at a chlorine dioxide pilot plant in Evansville, IN. Treatment variations included the use of liquid versus gaseous chlorine dioxide and the use of residual chlorine

Identification of Bromohydrins in Ozonated Waters

Because ozonation is becoming a popular alternative to chlorination for disinfection of drinking water and little is known about the potential adverse health effects of ozonation disinfection by-products (DBPs), we have sought to identify ozone DBPs, particularly brominated organics, which are of principal concern due to their anticipated toxicity. Using gas chromatography coupled (independently) to low-resolution electron-impact mass spectrometry (LR-EI-MS), high-resolution EI-MS, chemical ionization MS (with 2% ammonia in methane), and Fourier transform infrared spectrometry, we have identified a series of bromohydrins and related compounds detected in extracts of an ozonated natural water sample that was artificially enhanced with bromide. The bromohydrins, which constituted the majority of by-products in the samples we studied, were detected but could not be identified by GC/LR-EI-MS, the technique used almost exclusively for environmental monitoring. A key to identifying the bromohydrins was the manifestation of intramolecular hydrogen bonding in the gas-phase IR spectra. Many of the by-products had two chiral centers, and both diastereomers were present and were separated by GC. In most cases, the IR spectra also permitted us to distinguish between diastereomers. We interpreted the IR and EI-MS spectra of several representative compounds in detail, and gave peak assignments for all that were identified. Molecular mechanics calculations and an experimental determination of the enthalpy change for conversion of free and hydrogen-bound conformers for a representative bromohydrin were used to verify the IR interpretations.

Multispectral identification of alkyl and chloroalkyl phosphates from an industrial effluent

Multispectral techniques (gas chromatography combined with low and high resolution electron-impact mass spectrometry, low and high resolution chemical ionization mass spectrometry, and Fourier transform infrared spectroscopy) were used to identify 13 alkyl and chloroalkyl phosphates in a water sample taken from the effluent of a plant that manufactures fire-retardant chemicals. Of the 13 phosphates identified, only 4 were located in hbrary mass spectral data bases; thus, techniques other than conventional low resolution electron-impact mass spectrometry with data base matching were required. Several of the Identified phosphates are commonly used ftre retardants; however, three exhibited chemical structures different from those of the commercially manufactured fire retardants and the reactants used in their synthesis.