Localisation of IED manufacturing facilities by detection of explosives in sewage water

The objective of the EU-FP7 project EMPHASIS (Explosive Material Production (Hidden) Agile Search and Intelligence System) was to develop a system for detecting ongoing illicit production of explosives and improvised explosive devices (IEDs) in urban areas. The project started in 2011 and was finished in 2015. The EMPHASIS system is composed of several different networked sensors. Strategically positioned area sensors, monitoring the vapour phase as well as static sensors, positioned in the sewer, monitoring the sewage for traces of explosives were used. Information from all sensors is transferred to and assessed in a command centre. Air and water monitoring sensors allow the narrowing of the area to be searched. Mobile sensors are then used to pinpoint the exact location of the bomb factory. The consortium consisted of eight partners, research institutes (FOI, Fraunhofer ICT and IAF, TNO), industry (Morpho), SMEs (VIGO, Cascade) and an end user (Institut National de Police Scientifique). This paper presents final results concerning the detection performance of the sensors in the sewer system. Explosives, precursors to explosives and compounds from pyrotechnics can be disposed through the drain in the manufacturing of IEDs. Most of these compounds are present as ions when dissolved in (sewage) water leading to changes of the pH and the conductivity of the water. Within EMPHASIS we analysed these properties with ion selective electrodes (ISEs). An ISE is a sensor which converts the activity of a specific ion dissolved in a solution into an electrical potential which can be measured by a voltmeter or pH meter. In EMPHASIS we used a bunch of ISEs with different selectivities in order to facilitate the detection of a variety of compounds. This application was a new analytical challenge for these sensors. Related applications are known from research tasks such as tap water monitoring, analysis of contaminants of ground water and detection of sea mines by explosive traces. The established sensor techniques were applied in a new manner due to the complex matrix of sewage. The processing of this data with this highly variable background was a major challenge within in this project. Furthermore, realistic simulations with CFD (computational fluid dynamics) were performed to determine realistic velocities of flow, concentrations, dispersion and expansion of threat substances in sewage.