Cultivo da microalga Chaetoceros muelleri (Lemmermann, 1898) em efluente de carcinicultura e seu efeito na qualidade de água, produção de lipídeos e exopolissacarídeos

Abstract

The development of intensive aquaculture has generated environmental impacts as its effluents rich in organic matter are disposed off without prior treatment in aquatic ecosystems. Phytoremediation by microalgae is a promising alternative for treatment of aquaculture effluents, since in addition to improving water quality, the algal biomass produced can be used for a variety of purposes. This study has as objectives: to cultivate a marine microalgae species Chaetoceros muelleri, totally and partially, in a shrimp effluent; and to evaluate the rate of reduction of ammonia, nitrite, nitrate and phosphate, as well as, the yield of lipids and polysaccharides released (exopolysaccharides) in culture medium. Three treatments with different culture media, and three replicates each one, were evaluated: shrimp effluent (100% E), Guillard f /2 medium (100% G) and shrimp effluent mixture with Guillard f / 2 (50% G + 50% E). Growth of microalgae cultures was monitored daily by counting the cell density. The nutrient removal was evaluated through initial and final water analyzes in the culture media and the extractions of lipids and exopolysaccharides were performed at the end of the experiment. As a result, the different cultures showed similar cell growth. As for the nutrient removal in the culture media, the medium (50% G + 50% E) significantly removed more ammonia, nitrate and phosphate, and consequently has the greater efficacy in water treatment. The production of lipids was not influenced by the culture media, however, the media (50% G + 50% E) and (100% G) obtained significantly higher amounts. As conclusion, the cultivation of the C. muelleri using shrimp effluent is an excellent choice of phytoremediation, replacement of culture medium for the production of algal biomass and biomolecules.