The wastewater treatment plant (WWTP) of Torredembarra, located in the province of Tarragona, Spain, has suffered for years from noticeable odor emission problems, mostly during the summer season. During past years, the odor treatment in the WWTP relied on a series of biological and physico-chemical systems, which led to significant operating costs and which had fluctuating efficiency, mostly during summer season.

   In order to mitigate these odor emission events, a comprehensive restructuring plan was developed for this whole treatment system. The emission rates of the main odorous compounds in all the critical points of the WWTP were assessed during different times of the year. The most relevant odour emission areas were then confined, and the headspace air treated in a series of new and retrofitted biotrickling filters.

   Nitrogen is used in agriculture to fertilise croplands. During the spreading of fertilisers, a substantial part of Nitrogen is lost by volatilisation of ammonia (NH3). These emissions are responsible for unpleasant odours but are also mainly precursors of particulate matters (PM). In Europe, agriculture is one of the main source of nitrogen-composed PM. There is a need to collect more emissions data to understand better this activity impact.

   Measurement techniques of NH3, used for ambient air quality monitoring, are expensive and heavy to manage for the agricultural sector. Other techniques less expensive, like passive sampling, are also used to estimate ammonia flow, but these devices are not adapted for continuous monitoring. For this reason, we decided to customise a common e-nose device to detect ammonia emissions from fertilised grasslands. The sensor array was built using six commercial metal oxide semiconductor sensors. The sensors were inserted radially and evenly into a small size cylindrical PTFE chamber. Four of the selected sensors were sensitive to ammonia, one was sensitive to VOC and the last one was for combustible gas.