Tratamento de efluente em Lagoa de Alta Taxa e potencial energético da biomassa algal

Abstract

The high rate algal ponds (HRAP) comprise one of algal cultivation system types and provide treatment for various effluents with efficiency and economy. Understanding the limitations and mechanisms of the photosynthetic process, nutrients assimilation, degradation of organic compounds and consequent microalgae/bacteria growth are fundamental for the wastewater treatment and high biomass productivity. In summary, the study brought several contributions to the literature. First, the focus was algae cultivation in HRAP with UASB reactor effluent from the Wastewater Treatment Plant at UFLA as a source of nutrients (phosphorus, nitrogen and organic matter). By maintaining the temperature and hydraulic retention time (HRT) it was possible to determine the best cultivation condition with high biomass productivity, as well as, by laboratory analysis, it was possible to determine the removal efficiency in accordance with current environmental legislation for effluents disposal in water bodies. Under HRT of 10 days and variable temperature throughout the day, primary and total biomass productivity was observed at 0.13 and 4.85 g m-2 d -1 , respectively. In this operating condition, the removal of ammonia nitrogen, COD and total phosphorus were 89.86, 54.41 and 42.39%, respectively. Afterwards, the biochemical composition of generated biomass was analyzed in order to guide energy conversion routes development in the future. The proposed system obtained removal efficiencies above those required by legislation and the ability to generate biomass with significant properties for energy conversion, highlighting the carbohydrate content at 19.61%.