In natural environments, microalgae play a crucial role as a food source (primary producers), but also as oxygen producers and bioremediation agents, since during their development they can absorb excess nutrients that are harmful to the environment. In aquaculture, the use of biofloc technology promotes nutrient cycling and improves water quality, representing one of the innovative approaches to environmental sustainability. Effluent from biofloc-based farming systems contains high levels of nitrogenous and phosphate compounds, which can be used as nutrients in microalgae cultivation. This study aimed to investigate how the use of effluent from a super-intensive marine shrimp farming system with biofloc technology (BFT) affects the growth of Phaeodactylum tricornutum, a marine diatom, as a potential alternative culture medium.
For this, experimental cultures were developed under three treatments, with four repetitions each: LCA-AM Culture Medium (LCA-AM), commonly used at the Algae Cultivation Laboratory (LCA); Culture Medium with 100% effluent (BFT100); and Culture Medium with a 50% effluent and 50% LCA-AM mixture (BFT50).
Growth curves were developed and compared (Fig. 1), and the following parameters were analysed: maximum cell density reached, maximum biomass achieved (estimated by turbidity), cultivation time, and volumetric productivity.
Statistical analysis showed no significant differences (p>0.05) among treatments for any of the growth parameters evaluated (Table 1). A high removal of nitrogenous and phosphate compounds was observed.
It is possible to cultivate P. tricornutum in effluent from the biofloc system without the addition of nutrients in water, enabling higher productivity at lower costs.