Utilização do resíduo sólido de um sistema de bioflocos como meio de cultura para produção da microalga Navicula sp

Abstract

Microalgae are widely used in aquaculture for their high nutritional value, the objective of this study was to evaluate the growth of microalgae Navicula sp. using a solid residue biofloco cultivation system as culture medium. Therefore, two experiments were conducted: the first with the addition of trace metals to the environment with waste and the second without the addition of trace metals to the environment with waste, totaling five treatments (one control) with three replicates each: R0C100 (0% residue and 100% means Conway); R25C75 (25% waste and 75% medium Conway); R50C50 (50% waste and 50% medium Conway) R75C25 (75% waste and 25% medium Conway) and R100C0 (100% and 0% residue Conway medium). The crops had 10 days duration and were conducted in Erlenmeyer flasks with a volume of 1L, with initial inoculum of 5x104 cél.mL. The units were kept under constant aeration and luminosity of 2.000 lux, for monitoring the maximum cell density (DCM), doubling time (DT) and growth rate (K) were held daily counts with the help of a Neubauer chamber. The pH and temperature were measured at the beginning and end of the experiments, for statistical analysis tests were used Cochran, Shapiro Wilk, ANOVA and Tukey (P<0.05). Chemical analysis of the solid residue showed that it has 3,83 g/L of total nitrogen, 1,25 g/L total phosphorus and 0,32 g/L of sulfur. Water quality variables were in normal concentrations of cultivation. As for growth, even with no significant difference between treatments, the R50C50 treatment showed higher cell density in the experiment with trace metals and R25C75 treatment showed higher cell density in the experiment without trace metals, noting that the presence of trace metals favored growth Navicula sp. The study showed that the medium with residue can be used in any proportion in the cultivation of Navicula sp.