Biosensors for Water Quality and Monitoring and SensorViz Application
Water quality is a critical aspect of industrial and urban sustainability. A key challenge in wastewater treatment is assessing the biodegradability of organic pollutants, typically expressed as BOD (Biochemical Oxygen Demand) or COD (Chemical Oxygen Demand), which determines how effectively contaminants can be eliminated by biological treatment processes. Current conventional technologies are unable to estimate the biodegradability of organic matter in real time, forcing operators to rely on laboratory analyses that are time-consuming and unable to reflect rapidly changing conditions. Within the TRINEFLEX project, this challenge is addressed by combining advanced biosensors with intuitive digital tools such as SensorViz, developed by IMDEA and AIMEN.
Biosensors use electroactive bacteria as sensing element, to detect changes in water quality in real time. These bacteria naturally convert the biodegradable organic matter present in the water into an electrical signal, which can be directly related to the biodegradability of the contaminants in the wastewater. One of the biosensor installed in the ESAMUR wastewater treatment plant is shown in Figure 1.
Figure 1: Biosensor installed in the biological treatment stage of the ESAMUR wastewater treatment plant.
The electrical current produced by the electroactive bacteria is not solely determined by the biodegradable content of the water. Other physical and chemical parameters, such as presence of dissolved oxygen, temperature, pH, and conductivity, also influence bacterial activity and therefore affect the signal generated. To account for these effects, additional probes commercially available have been installed alongside the biosensors to continuously measure these variables. Furthermore, laboratory analyses are carried out to quantify how each of these parameters influences bacterial current production, allowing the models used to predict BOD and COD to be refined and improved over time.
Installed at different points of a wastewater treatment plant, these biosensors continuously monitor key parameters and can quickly signal abnormal conditions. However, the real value of these sensors lies in the ability to transform their data into clear and actionable information.
This is where SensorViz comes into play. The tool is designed to make biosensor data easy to understand and use, even for non-expert users (Figure 2). Through a simple and interactive dashboard, operators can visualise what is happening inside the plant at a glance—tracking water quality trends, identifying anomalies, and responding more quickly when needed.
Behind this simplicity lies a robust digital architecture. A backend service collects data from the biosensors via the Kharon platform and makes them available through an API, while a Grafana-based dashboard translates these data into dynamic graphs. Users can customise their view by selecting time ranges, adjusting how frequently data are displayed, and choosing which variables to monitor.
The result is a flexible tool that supports both real-time monitoring and the analysis of historical trends. Each biosensor can provide multiple variables, allowing a detailed yet accessible overview of the system’s behaviour.
SensorViz has been carefully tested to ensure that the data displayed accurately reflect real conditions and respond correctly to user interactions. It is currently operational within the TRINEFLEX TRAIN environment, with ongoing integration into the project’s Decision Support System (DSS), which will further enhance its role in supporting informed decisions.
By turning complex sensor data into clear visual insights, SensorViz helps bridge the gap between advanced technology and everyday operations. It represents a concrete step towards smarter and more sustainable water management—where data are not just collected, but truly understood and used
Figure 2: SensorViz platform displaying the real-time signal of one of the biosensors, together with the associated alarm system.
