Avaliação do cultivo de microalgas em efluentes domésticos tratados na ETE- Jaracati, São Luís-MA: isolamento, ficorremediação e produção de biomassa

Abstract

The frequent degradation of water by the release of effluents has increased the search for efficient and effective solutions for the treatment of wastewater. In this sense, the application of microalgae for the treatment of effluents has been highlighted, due to these organisms in nutrient removers and ability to metabolize compounds with high added value. Thus, the objective of this work was to evaluate the cultivation of microalgae isolated in domestic effluents, previously treated at the Jaracati Sewage Treatment Station (ETE-Jaracati), located on the island of Maranhão, aiming at the tertiary treatment of effluents and the algal biomass production. The present study carried out the isolation of two species of microalgae, which were identified as Asterococcus sp. and Tetraselmis sp. For each species isolated from the effluent, experiments were conducted on a laboratory scale, in batch, through a completely randomized design, with six treatments (CRT, T1, T2, T3, T4 and T5) and three replications, totaling 18 experimental units. To evaluate the efficiency of microalgae in removing dissolved nutrients, samples of cultures were submitted to analytical procedures to determine the concentration of phosphate (PO4 3- ) and N-ammoniacal (N-NH4 + ). In the present study, both microalgae species isolated were able to grow in the ETE-Jaracati effluent, and the species Asterococcus sp. reached the highest algal growth rates, highest growth velocity and lowest doubling time in relation to Tetraselmis sp. For the remediation of nutrients, the two species were efficient in removing the analyzed nutrients, the species Tetraselmis sp. obtained maximum remediation efficiency of 75.3% (PO4 3- ) and 99.5% (N-NH4 + ), while Asterococcus sp. removed 70.7%

(PO4 3- ) and 99.6% (N-NH4 + ) from the effluent. These results showed that both microalgae species, isolated from the ETE-Jaracati effluent, were efficient in the tertiary treatment for nutrient removal, at the same time they were able to adapt and grow in wastewater, showing potential for biomass production.