Closed-Loop Water Recirculation and IoT-Based Monitoring System for Aeroponic Cultivation

Aeroponic cultivation has gained popularity as a sustainable alternative for urban agriculture since it gives the possibility to produce food in reduced areas. These cultivation systems enable the reuse of water and fertilizers, reducing costs. Moreover, the performance of crops depends on maintaining the nutrient solution, at adequate levels of pH and electrical conductivity (EC).

In this work, we present a Closed-Loop Recirculation System and Internet of Things (IoT)-Based Nutrient Solution Monitoring System for Aeroponic Cultivation. This system allows users to access the data remotely and to adjust the recirculation time intervals.

The recirculation system is based on two tanks called the main tank and monitoring tank, two pumps called the irrigation pump and recirculation pump, a solenoid valve, and calibrated pH, temperature, and EC sensors. This system sends the data to the cloud for remote access, and also stores the measurements on an SD card.

The nutrient solution is stored in the main tank. After irrigation activation, the recirculation pump is activated to transfer the liquid to the monitoring tank, where the sensors are located and the data is captured. Finally, the solenoid valve is activated, and the liquid returns to the main tank.

The results obtained during the calibration process shows a coefficient of determination (R²) of 1.0, 0.9996, and 0.9999 for the pH, EC, and temperature sensors, respectively. The aeroponic system was evaluated with 70 lettuce plants during two months. During this period, the pH remained between 5.3 and 7.3, while the EC ranged from 1371 to 2940 µS/cm. All the plants remained healthy during the study period.

These results indicate that sensors, wireless communication, and water recirculation can be effectively integrated into aeroponic systems to improve resource management. As future work, an intelligent control method will be incorporated to optimize the application of fertilizers.