Emerging trace organic contaminants (TrOCs) are broadly defined as any synthetic or naturally occurring chemicals that have not been routinely monitored but have the potential to enter the environment and cause known or suspected adverse ecological or human health effects . Most of these TrOCs are from municipal, agricultural and industrial wastewater sources (see Figure 9.1). Their release to the environment had likely occurred for a long time but was only recently recognised by new and advanced analytical methods . In some cases, emerging contaminants can also result from the synthesis of new chemicals either intentionally as a chemical of industrial interest or unintentionally as a by-product. A notable example of the latter is the N-nitrosamine group that can be formed as by-products due to a range of industrial activities including the production of rocket fuel, rubber and tobacco as well as water or wastewater disinfection by chloramine .