Análise da eficiência de um aerador de baixo custo e avaliação da qualidade da água em sistemas intensivos de produção de tilápias com bioflocos em diferentes densidades de estocagem

Abstract

Among the types of production system applied in aquaculture, the system bioflocos (BTF) is becoming more popular due to its sustainable practices. Highlighting is low or zero water exchange, formation of the population of predominantly autotrophic and heterotrophic microorganisms, resulting in microbial flocs. Taking into consideration the effectiveness of the system in the production of tilapia, This study aimed to the construction, implementation and analysis of the efficiency of an inexpensive aerator. Assess and control the physical and chemical parameters of water. 3780 fingerlings of Nile tilapia with initial average biomass of 3±0.5 g, 24 distributed in rectangular tanks with a volume of 125 liters. The experiment had 6 treatments (T1 - 360 fish.m-³, T2 - 1800 fish.m-³, T3 - 1080 fish.m-³, T4 - 1440 fish.m-³, T5 - 720 fish.m-³ and T6 - 2160 fish.m-³) and four replications. The study lasted 60 days. We analyzed the effect of the venturi aerator efficiency and water quality parameters. They were compared using statistical analysis, using the SISVAR® software. Data were subjected to analysis of variance (ANOVA) and verified by F test (p <0.05). Mean comparisons were performed by Tukey test at 5% significance. The results for room temperature between treatments were maintained between 26 and 28 ° C. The dissolved oxygen were above 3 mg L-1. The pH remained close to 7.20 (recommended by some authors). As the alkalinity values given in mg.L-1, you have T1 = 68.75±18.49ª, T2 = 98.50±28.48c, T3 =71.75±21.83ª, T4 = 95.50± 30.29c, T5 =68.08±20.81ª and T6 = 77.50 ± 22.79b. To nitrite, data were obtained: T1= 1.57±1.97a, T2 = 1.47±1.42 a, T3 = 1.42±1.40a, T4 = 1.20±1.34 a, T5 = 0.98± 1.41a and T6 = 3.06±2.62b. For total ammonia: T1 = 0.99±1.23a, T2 = 0.97±1.08a, T3 = 1.58±1.24a, T4 = 1.27±1.04a, T5 = 1.10±1.43a and T6 = 1.02± 0.64a. Nitrate: T1 = 2.71± 1.79a, T2 = 2.94± 2.70a, T3 = 2.78± 2.42a, T4=2.56±1.89a, T5 = 2.80± 2.21a and T6 = 3.02±2.95a. Phosphate: T1 = 23.62±16.11a, T2 = 25.10±15.02a, T3 = 23.81±13.45a, T4 = 26.54±16.09a, T5 = 24.83±14.51a and T6 = 26.89± 15.19a. From the analysis of dissolved oxygen showed that the aerator Venturi effect was efficient during the experiment, achieving the desired levels, taking into account also the ease of applicability and low cost for its development. Through the analysis of the physico-chemical parameters of the water and the mortality during the experiment, one can also conclude that the safer to operate using the bioflocs density is up to 720 fish.m-³.