Assessment of Disinfection By-Products Formation by Oxidizing Iodinated Contrast Media by Sequential Ozone-Ultra Violet Light Followed By Chlorination and Chloramination

Abstract

The increasing population worldwide has caused water demand and stress in water supply, therefore water reuse has taken interest in wastewater treatment plants. Iodinate contrast media (ICM) is a contaminant of emerging concern (CEC) that can be poorly removed during conventional biological processes along wastewater treatment plants, therefore it can reach surface water and groundwater at ppb level. This ubiquitous contaminant can be removed it by advanced oxidation processes (AOP) such as low-pressure ultra violet light (LP-UV) and ozone. In this dissertation, a LP-UV AOP with different oxidants (i.e. hydrogen peroxide, free chlorine, and monochloramine) are tested to remove seven targets ICMs in groundwater. The idea is to look at whether the addition of oxidants can enhance the abatement of target ICMs. Surrogate organic parameters were measured and correlated them to the removal of each ICM. A surrogate correlation model was developed to predict the removal of individual ICMs. In addition to the surrogate correlation models, a disinfection by-products (DBPs) assessment was carried out. For this purpose, a sequential oxidation treatment ozone-LPUV followed by chlorination and chloramination was implemented. The model compound to study was iopamidol. Different treatment conditions were tested such as ozone doses, UV dose or fluence and chlorinated oxidants reaction times. Three major groups were studied: trihalomethanes (THMs), Haloacetonitriles (HANs) and haloaecetamides (HAMs). Results showed that ozone-LPUV post chlorination produced the lower content of DBPs.