Occurrence of iodinated X-ray contrast media in indirect potable reuse systems

Abstract

A lack of knowledge of the health and environmental risks associated with chemicals of concern (COCs) and also of their removal by advanced treatment processes, such as micro-filtration (MF) and reverse osmosis (RO), have been major barriers preventing establishment of large water recycling schemes. As part of a larger project monitoring over 300 COCs, iodinated X-ray contrast media compounds (ICM) were analysed in treated secondary wastewater intended for drinking purposes. ICM are the most widely administered intravascular pharmaceuticals and are known to persist in the aquatic environment. A direct injection liquid chromatography tandem mass spectrometry (DI–LC–MS/MS) method was used to monitor secondary treated wastewater from three major wastewater treatment plants in Perth, Western Australia. In addition, tertiary water treated with MF and RO was analysed from a pilot plant that has been built as a first step in trialling the aquifer recharge. Results collected during 2007 demonstrate that MF/RO treatment is capable of removing ICM to below the analytical limits of detection, with average RO rejection calculated to be greater than 92%. A screening health risk assessment indicated negligible human risk at the concentrations observed in wastewater.

Keywords:

• Iodinated X-ray contrast media
• reverse osmosis
• wastewater
• water reuse
• chemicals of concern
• pharmaceuticals and personal care products

Acknowledgments

This study was part of the Western Australian Premier's Collaborative Research Program “Characterising Treated Wastewater for Drinking Purposes Following Reverse Osmosis Treatment”. The authors would like to thank all project partners, particularly staff at the Water Corporation of Western Australia and CSIRO Land and Water who arranged sample collection, as well as the Department of Health for advice on drinking water guideline limits. We would also like to thank A. Chan from CWQRC for his valuable assistance in the laboratory. The LC-MS/MS instrumentation was funded by an Australian Research Council (ARC) LIEF grant.

Notes

∗RO rejection using virgin membranes;

∗∗RO rejection using fouled membranes.