Comparativo entre tensoativos orgânicos e inorgânicos em processo de flotação por ar dissolvido utilizando efluente de lagoa de alta taxa para cultivo de microalgas (LAT) alimentada com efluente sanitário

Abstract

The availability of clean and renewable energy for the future is one of the biggest challenges of society and is closely linked to global stability, economic prosperity and quality of life. The recovery of energy from biomass has been studied by several researchers in the last decades. An attractive alternative is the production of biomass coupled with treatment of effluents to allow for cost reductions. This work presents the cultivation of algal biomass in high-rate pond (HRP) with subsequent separation by dissolved air flotation (DAF) using two surfactants. The HRP was operated under two different regimes, varying the hydraulic retention time (HRT), which was initially operated with 3 days HRT and then 7.5 days. In the first regime it was obtained a biomass concentration of 90.7 ± 44 and of 125.6 ± 68.3 mg / L in the second. Moreover, the production per area was highest during the first operation regime 9.1 ± 4.4 g / (m² ∙ d) compared to the second 5.0 ± 3.4 g / (m² ∙ d). Separation of the biomass (dewatering) was achieved by means of DAF, using an organic flocculant (Tanfloc sg) and an inorganic coagulant (ferric chloride), the former being more effective for the removal of biomass, 88.2 ± 4.3% when compared to coagulant, 66.8 ± 11%. The operating costs per hour of ferric chloride was smaller, R$ 2.67, compared with Tanfloc sg, R$ 2.98, however to remove the same amount of biomass, Tanfloc sg showed lower cost.