Análise da biomassa e do óleo microalgal de lagoa de estabilização

Abstract

Stabilization ponds produce effluents with high amounts of biomass that are transmitted to the receiving lagoons, which can lead to environmental damages. However, this seaweedy biomass, originated from the stabilization ponds’ effluent, can be removed and applied in several ways, mostly used as an energy source (biofuels). Therefore, the main purpose of this work is evaluating biomass metabolic constituents profile from stabilization pounds in Ponta Negra (Natal - RN) aiming its future applications. A qualitative and quantitative characterization of the microalgae species present in the stabilization ponds was carried out. The biomass was removed from the effluent by centrifugation and air flotation techniques using aluminum polychloride (100mg/l) and ferric chloride (75mg/l) coagulants. The extraction method was mixed using solvent system n-hexane / magnetic stirrer and ultrasonic bath. The lipid material extracted from the sample was analyzed by Fourier Transform Infrared Spectroscopy (TFIR), thermogravimetry and thin-layer chromatography. After the oil extraction, the dry and residual biomass was evaluated by atomic absorption spectrophotometry. The results show that the predominant species detected in the lagoons were Synechococcus sp (10%), Synecocytis sp (43%) and Chlorella sp. (36%). The average yield of the lipid material content extracted from the biomasses was 3.83%. The Infrared spectra and chromatography results indicated the presence of ester, fatty acids and triglycerides without extract the lipid material from the biomass. Also, atomic absorption analyzes detected significant presence of total iron and aluminum contents in the residual samples. In summary, results show that the lipid material extracted from the stabilization pond has the potential to produce an oil rich in triacylglycerides capable of being reused by biodiesel production. In addition, it was verified that the coagulants used in the propagation process caused an increase in the concentration of metals, limiting their reuse in future applications.