2.4.1. IoT System Demonstration in a Wastewater Treatment Scenario

The first experiment consisted of demonstrating the features implemented at the IoT application level. To do this, eight devices have been deployed in four WWTP located in the Region of Murcia (Spain): Alcantarilla, Molina de Segura, Los Alcázares, and San Pedro del Pinatar. A device has been placed at influent and effluent of each plant. During the test, devices have collected data related to nitrate and nitrite concentrations during the month of May 2019, twice a day, regardless of their location. This sampling frequency is appropriate for water quality monitoring applications, hence the term *near-real-time*. Note that the sampling frequency for traditional manual water quality monitoring techniques is usually once a week. The data transmitted by the devices are captured, stored, analyzed, and finally represented through the user interface by means of different customizations that compose the IoT application hosted in the system platform. In Section 3.1, all the customizations implemented in the integrated system are presented.
