Automação no monitoramento e controle do oxigênio dissolvido na água de um sistema de recirculação para cultivo de tilápia do Nilo

Abstract

Advances in the development of new technologies have transformed the reality of the aquaculture sector. Nowadays, there are modern autonomous systems that perform repetitive activities and help maintain a stable production environment. Among these systems there are automated feeding and monitoring and control of water quality parameters, such as temperature, pH and dissolved oxygen, considered the most important. This work aimed to install an automation system to monitor and control dissolved oxygen in the water of a recirculation system to turn on and turn off the oxygenation system, saving electricity consumption. The research was carried out at the Estação de Aquicultura of the Federal University of Ceará. The recirculation system included 6 circular tanks with a volume of 250 L and a water treatment system containing a primary clarifier, secondary clarifier, mechanical filtration, biological reactor and equalizer. Coupled to the equalizer, an oxygenation system was installed comprising an ultrafine bubble generator and an oxygen concentrator. Each tank was stocked with approximately 1,150 g of Nile tilapia weighing approximately 130 g. The automation system consisted of an Arduino microcontroller, an oxygen sensor, a signal inverter board, an OLED display and a relay that activated and turned off the oxygen concentrator of the oxygenation system. Nile tilapia presented zootechnical performance as expected for the species, with survival of 100 ± 0,0%, and growth of 19,7 ± 0,5 cm, with an average biomass gain of approximately 118.3 g for each of the six tanks. The water quality parameters were within the comfort range for the specimens, with total ammonia at 2,2 ± 0,5 mg/L, non-ionized ammonia at 0,01 ± 0,0 mg/L and pH at 6,9 ± 0,1. Dissolved oxygen concentration (DO) values remained within the limits established in the programming (4,0 mg/L < DO < 8,5 mg/L) throughout the experimental period. Based on the results found, it was possible to see that the equipment guaranteed the supply of oxygen to the tilapia stored in the system without any need for human interference.