Effluents from wastewater treatment plants are disinfected with chlorine to control waterborne diseases, which still afflict thousands of people each year in the United States. Fish kills, fish avoidance and losses of aquatic wildlife diversity have been described near treatment plants discharging chlorinated water, and these usually result in severe economic hardship for fishermen. Some of the chlorinated compounds formed during the chlorination of wastewater have been found to be carcinogenic or toxic to aquatic organisms like fish. Consequently, there is safety concern over the consumption of these aquatic organisms because of the present trend towards increased consumption of seafood, fish, etc., to reduce the intake of fat-rich meat. Whether the consumption of these aquatic organisms will result in cancer in the human population is not yet clear. Residual chloro-oxidant is present even in SO2 dechlorinated wastewater effluent (the most common form of dechlorination) and this sulfite resistant oxidant, is extractable into octanol. This indicates that these oxidants are hydrophobic which might explain part of the adverse effect on organisms at receiving streams of wastewater treatment plants. This project is geared towards the isolation, characterization, and toxicological testing of these oxidants. Two undergraduate students will test the hypothesis that this sulfite resistant oxidant consists of organic chloramines which are formed by the chlorination of peptides and proteinaceous compounds. Hydrophobic chloramines such as N-chloro-cyclohexylamine, appear to be nearly as toxic as HOC1 to fish. The hydrophobic character of the sulfite resistant oxidants may therefore make them toxic to organisms in receiving streams. The student participants will determine the class of compounds that contribute to the source of the residual oxidant in dechlorinated wastewater effluent, by studying the chlorination/dechlorination properties of amines, proteins and peptides. They will develop an effective method for the destruction of the residual oxidant. Radioactive chlorine will be used as a tracer in the chlorination of model compounds, and in the isolation and characterization of the oxidant present in sulfite dechlorinated wastewater. High performance liquid chromatography (HPLC) with fluorescence detection will be used in the characterization of the oxidant, and a fluorometer will be used to determine rate constants for the chlorination and dechlorination reactions. The complex reaction between S(IV) agents and chlorinated secondary amines and peptides will be studied to determine the persistence of the residual oxidant in the environment. The data obtained will serve as preliminary data for the toxicological experiments using fish or a suitable cell culture. Ultraviolet spectroscopy and fluorescence techniques will be used to conduct this study.
