Recuperação de microalgas em lagoa de maturação por meio de floculação alcalina
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2019-10-11
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Universidade Federal de Goiás
Resumo
The biomass produced by microalgae can be used to various ends. Given the cost demanded to its
cultivation and biomass harvest, the conventional liquid medium separation mechanisms are not viable.
In face of that, alkaline flocculation, with the cultivation in wastewater, has the potential to overcome
the limitations on energy and nutritional costs. The present study aimed to test the alkaline flocculation
followed by sedimentation in maturation ponds from ETE Goianira (in the city of Goianira, Goiás), as
well as the lipid content obtained from the generated sediment. Three different bases were used to
induce pH to the desired value (NaOH, CaCO3 and Ca(OH)2) in five pH ranges (8, 9, 10, 11 and 12).
Ca(OH)2 presented the best efficiencies, reaching an average >70%, although the use of this base
implicated on a higher sediment volume, which may be a limiting factor. The NaOH showed efficiency
>40%, producing smaller amount of sludge and, consequently, higher lipid/sedimentation ratio. During
the tests, NaCO3 was not feasible to induction of alkaline flocculation. In general, the achieved
efficiencies were consistent with what is presented in the literature. The efficiencies were below trials
conducted with cultivation of isolated genera or species, or in a controlled environment. A total lipid of
125 and 286 mg.L-1 were extracted in the use of NaOH and Ca(OH)2, respectively. There are evidences
that the presence of other microorganisms may interfere with the achieved efficiency, reducing the
efficiency on the microalgae biomass recovery, but without making alkaline flocculation unfeasible.
The alkaline flocculation could be used to biomass recovery in maturation pond, with margin for
efficiency improvement. The method can be used as a treatment, since it seems to reduce the
concentration of orthophosphates, calcium and magnesium, microalgae and other negatively charged
microorganisms.
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MARINHO, P. H. O. Recuperação de microalgas em lagoa de maturação por meio de floculação alcalina. 2019. 88 f. Dissertação (Mestrado em Engenharia Ambiental e Sanitária) - Universidade Federal de Goiás, Goiânia, 2019.