Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Disinfection By-Products in Potable Reuse Water and Interpretation of Their Relative Toxicities

Auteur : McKenna, Elizabeth

Université de soutenance : University of Nevada Reno

Grade : Master of Science in Civil and Environmental Engineering 2020

Résumé partiel
To preserve water resources, many arid regions have started recycling water via direct or indirect potable reuse treatment systems. One of the pitfalls of reused water is the potential for disinfection by-products (DBPs) to form and persist in the systems–many of which are carcinogens. DBPs form from reactions between disinfectants and organic or inorganic matter.Many methods have emerged to analyze and interpret DBP data. One such method, called “predicted toxicity,” has been used to compare the efficacy of different water treatments. Dividing each measured DBP concentration by an experimentally determined toxicological index, results in the relative contribution to the overall DBP associated toxicity of a sample, and summing the products results in a total “predicted toxicity” of a water sample, which is compared to other samples or water treatment methods. This thesis shows that this method of data use may result in biased conclusions due to the inability of any study to measure all DBPs. I removed or added actual or simulated DBP measurements to those of published studies which evaluated granular activated carbon as a treatment to reduce the relative toxicity of the effluent. In one example, removing measured haloacetaldehydes from the data caused the predicted cytotoxicity of a treated sample to decrease by up to 47%, reversing the initial conclusion that activated carbon increased the toxicity of the water. Though this additive approach should be carefully used when evaluating water treatments, it is an appropriate tool to demonstrate which species dominate toxicity. Understanding which compounds are more toxic than others can help inform future water regulations.Nitrosamines, especially N-nitrosodimethylamine (NDMA), are potential human carcinogens that form from reactions of chloramines (a common disinfectant) with nitrogenous organic matter

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