The wastewater composition can vary strongly depending on the location of the wastewater treatment plant (WWTP) and the type of influent streams. For instance, high concentrations of SO4 2-, Na + and Cl -can be expected in coastal WWTPs, where seawater intrusions can occur . Even higher salt loads can be found in specific places like Hong-Kong, where seawater is directly used to flush toilets . It is also common for WWTPs to process some industrial wastewater, which can bear important loads of diverse elements, depending on the type of industry.