Ultrafine bubble generator for oxygenation of Nile tilapia (Oreochromis niloticus) breeding tanks under recirculating water system

The objective of this work was to evaluate the use of an ultrafine bubble generator of own manufacture for oxygenation of Nile tilapia (Oreochromis niloticus) breeding tanks in a recirculating water system. The research was divided into two steps: 1) oxygen saturation test; 2) application of ultrafine bubble production technology for the breeding of Nile tilapia. In the first step, the water of a 2.0 m3 test tank was completely deoxygenated and the ultrafine bubble generator was turned on for 60 min. In the second step, the generator was connected to the water recirculating system for breeding of Nile tilapia to compare the overall performance of this system with other under conventional aeration system. The ultrafine bubble generator could reach 100% oxygen saturation in the test tank (27.8 °C) in approximately 21 min and, at the end of 60 min, the concentration was 21.8 mg L-1 (277.52% saturation). The results showed significant difference (p<0.05) between the mean dissolved oxygen concentration in the treatment with ultrafine bubbles (9.80 ± 3.68 mg L-1) and the treatment with conventional aeration (3.47 ± 0.88 mg L-1). No significant difference (p>0.05) was found for the zootechnical performance parameters evaluated. The conclusion was that the ultrafine bubble generator is more efficient to maintain a high dissolved oxygen concentration in the recirculating water in Nile tilapia breeding tanks than the conventional aeration system.