Fotogranulação e recuperação de fósforo em fotobiorreator em bateladas sequenciais no tratamento de esgoto doméstico de baixa carga orgânica

Abstract

The application of the algal-bacterial consortium in the treatment of wastewater has been studied for several aspects beyond the reduction of pollutant load. Among these aspects, the high nutrient removal capacity and the potential for utilization of excess biomass stand out. Therefore, this study investigated the performance of the algal-bacterial granular consortium in a photobioreactor in sequential batches, operating with 4 h cycles, treating synthetic domestic wastewater under light intensity, as well as evaluating the phosphorus recovery capacity in the biomass. To achieve the objective of this research, a transparent acrylic photobioreactor was constructed with a useful volume of 3.5 L, with a height/diameter ratio of 8 mm and a volumetric change of 55%. The system was inoculated with the mixture of aerobic sludge from a sludge station activated by prolonged aeration. Aerobic granules were obtained in the photobioreactor, and granules with diameters between 0.2 and 1 mm were formed. Throughout the experiment, the COD removal efficiency averaged 88% and remained stable throughout the experiment. The system achieved 72% nitrogen removal efficiency, so the microalgae growth may have contributed to this removal. Chlorophyll concentration reached 5.8 mg/L in the photobioreactor, indicating a symbiosis between heterotrophic bacteria and microalgae. Concentrations were noticeable in five fractions of phosphorus present in the biomass, found concentrations of 4.9 mg/g.SSV, 4.1 mg/g.SSV, 5.4 mg/g.SSV, 1.4 mg/g.SSV, 0.38 mg/g.SSV for total, organic, inorganic, apatite and non-apatite phosphorus, respectively, showing the potential for application in agriculture.