Development of a water quality sensor: Electrochemical Impedance Spectroscopy to monitor a broad range of (micro)contaminants in a single device

Large quantities of water are used worldwide for various industrial purposes and communal uses. Wastewater from e.g. petroleum or food industry, must be treated to remove a variety of chemical contaminants before it can be discharged to surface waters. It is necessary to monitor the effectiveness of this water treatment, both for operational control and to comply with regulations. However, with current monitoring methods that rely on grab sampling composite sampling or the application of sensors, timely, cost-effective detection of incidents that overload the wastewater treatment plant is not always possible. Thereby risking that such incidents will not be detected timely to take mitigating measures. While sensors enable continuous and near real time monitoring, they almost all provide information on sum-parameters. This means that the presence and/or concentration of a group of contaminants can be measured, but that no information about individual contaminants can be obtained.
Currently, no sensor exists that combines the specificity and sensitivity in order to detect and identify a wide range, let alone all, possible contaminants. However, electrochemical Impedance Spectroscopy (EIS) has the promise to provide such a capacity. Therefore, the application of EIS for monitoring of water quality has been investigated.