Eficiência do carvão ativado do caroço do açaí (Euterpe oleracea) como mídia filtrante em Sistema de Recirculação para Aquicultura (SRA)

Abstract

The present study aimed to evaluate the efficiency of different proportions of activated charcoal from açaí seed (ACAS) in WRS and its influence on water quality, as well as on with zootechnical performance of tambaqui (Colossoma macropomum). The experiment occurred in a completely randomized way, with four treatments and three repetitions according to the following treatments: T1: 0% of ACAS; T2: 50% ACAS; T3: 75% ACAS; T4: Biological filter only (Control group). The ACAS used was characterized physically-chemically through moisture content, ash content, porosity, apparent specific mass and scanning electron microscopy (SEM) for structural analysis. The experiment lasted 60 days, where 1,200 tambaqui juveniles were used, divided at a density of 100 ind./m³ with an average starting weight of 3.35 ± 0.60g. Water collections were made in the morning at two points: after passing through the cultivation tank and after passing through the filter. To evaluate the efficiency of the filter and the quality of the water in the culture system, the following parameters were monitored: Temperature (° C); pH; dissolved oxygen (mg / L); electrical conductivity (µS / cm); turbidity (FNU); dissolved solids (mg / L); Total Ammoniacal Nitrogen (mg / L), nitrite (mg / L); nitrate (mg / L); total phosphorus (mg / L); alkalinity (CaCO3mg / L); total suspended solids (mg / L) and apparent color (UC). The final average weight, weight gain, biomass gain, feed conversion, average feed consumption and survival were also evaluated as zootechnical performance indexes of the cultivated fish. The data were submitted to the Shapiro-Wilk normality tests (α = 0.05); to the analysis of variance (ANOVA) (α = 0.05) and Kruskal Wallis (α = 0.05) followed by the Tukey test (α = 0.05) to verify the difference between treatments. Animal performance data showed no significant differences between treatments. Most parameters of water quality evaluated in the fish culture tank were within the recommended for the species. The filters composed by ACAS, were more efficient in removing turbidity, however for TAN and NO2 this efficiency was greater in treatments with higher percentages. It was found a greater efficiency in the nitrification process for these treatments. Therefore, the alternative media is an option to be used in WRS.