Disinfection Byproducts in Direct Potable Reuse and Conventional Drinking Waters: Influence of pH, Cu2+, and Water Age under Distribution System and Premise Plumbing Conditions.
Journal Article
Overview
abstract
Disinfection byproduct (DBP) formation and transformation in distribution and premise plumbing systems are incompletely characterized, especially in wastewater-impacted waters. We evaluated the impact of pH, Cu2+ addition, and water age on 54 regulated and unregulated DBPs after chlorination of direct potable reuse (DPR) and conventional drinking waters. DPR water produced 1.6× higher DBP and 3.9× higher calculated additive toxicity (CAT) yields than conventional drinking water. Iodinated trihalomethanes (I-THMs) reached 63 μg/L in DPR and 25 μg/L in conventional drinking water. Raising pH to 10 increased trihalomethanes, I-THMs, and dihalogenated haloacetamides but decreased haloacetaldehydes. CAT values decreased with increasing pH, primarily due to base-catalyzed degradation of more toxic DBPs. Cu2+ addition had minimal impact on DBP formation and speciation, except for hindering I-THM formation in both waters and catalyzing trichloroacetaldehyde formation in the conventional drinking water. DBP levels increased over time at pH 7-8 but not at pH 10. CAT declined at pH 7 and remained stable at pH 8-10, indicating that higher water age does not necessarily increase DBP risk. CAT results have the caveat that they are inherently relative; they are intended for comparative purposes between water types and conditions rather than as an absolute measure of risk.
