Evaluating the capacity of a drinking water treatment plant to remove the disinfection by-product precursors.

International audienc

Formation and removal of disinfection by-products in a full scale drinking water treatment plant

International audience13 In this case study, high sensitivity simple methods for the analysis of trihalomethanes (THM4), 14 iodinated-trihalomethanes (I-THMs), haloacetic acids (HAAs), bromide, iodide and iodate have been 15 developed. A one-step procedure for the analysis of haloacetic acids by head-space GC-MS provides 16 good reproducibility and low limits of quantification (≤ 50 ng L-1). These methods were applied to 17 characterize the formation of DBPs in a full scale drinking water treatment plant. In this treatment 18 plant, the incorporation of bromine into THMs increases throughout the water treatment line, due to 19 the formation of bromine reactive species favored by the decrease of competition between DOC and 20 bromide towards chlorine. A linear correlation has been observed between the bromine incorporation 21 factor and the Br-/DOC mass ratio. The conversion of iodine to iodate by chlorination occurs in this 22 water due to the relatively high bromide concentration. Moreover, a higher formation of iodate 23 compared to iodide levels in the raw water is observed indicating a degradation of organic iodinated 24 compounds. The formation of I-THMs was constant in terms of quantity and speciation between 25 campaigns despite fluctuating concentrations of DOC and total iodine in the raw water. A preferential 2