CHAPTER 6: NDMA Formation After Coagulation with Ferric Chloride and Decarbonation

The N-nitrosamines are a group of emerging disinfection byproducts (DBPs) that are considered as probable human carcinogens. Of all the nitrosamines, N-Nitrosodimethylamine (NDMA) has been most commonly detected in drinking water and wastewater. Particularly, the presence of NDMA is of concern in locations where wastewater effluents are used for potable reuse. Thus, to investigate treatment processes specifically aimed at removing/transforming nitrosamine precursors is crucial to avoid high formation of these carcinogenic DBPs. In this study, coagulation with ferric chloride of a wastewater effluent destined for potable reuse was investigated to evaluate ozone NDMA precursor removal. Furthermore, the effect of carbon dioxide concentration in the effluent of an indirect potable reuse system in NDMA formation during chloramination was investigated as strategy to control NDMA formation. Results of the study showed that coagulation with ferric chloride is not effective in NDMA precursor removal and that the carbon dioxide concentration in water seems to not affect NDMA formation during chloramination.