Occurrence, monitoring and removal of drinking water contaminants by advanced technologies

In order to maintain drinking water primary standards compliance under the USEPA Stage 2 Disinfectant Disinfection Byproducts Rule, drinking water treatment plants (DWTPs) are switching from free chlorine (FC) to chloramines (MCA). Concerns are raised as MCA disinfection has been linked N-nitrosamine formation. N-nitrosamines are a group of nitrogenous DBPs (N-DBPs) which are highly carcinogenic in comparison to regulated DBPs (THMs and HAAs, generated by FC disinfection). Also in the forefront of drinking water concerns are other emerging drinking water contaminants such as perchlorate. Perchlorate is a contaminant which can enter drinking water from natural deposits or through introduction by anthropogenic actives and applications which the USEPA has decided to regulate. To contend with current drinking water issues, two major areas were targeted: (1) perchlorate removal and (2) drinking water DBP and emerging contaminant formation by an alternative disinfectant (peracetic acid, PAA). Perchlorate monitoring was performed at higher risk DWTP locations within the state of Missouri with levels below the estimated regulatory limit (4 µg/L or higher). Perchlorate removal from drinking water was also studied by adsorptive materials: powdered activated carbons (PACS) and clays. Out of all the materials studied, one clay (TC-99) had efficient removal with quick kinetics. PAA disinfection was studied to determine the formation of THMs, HAAs, HNMs, perchlorate, bromate, and N-nitrosamines. In comparison to FC and/or MCA, PAA disinfection yielded significantly less of the monitored contaminants, with the majority remaining below their respective detection limits --Abstract, page iv