Aplicação de biossurfactante na remoção de escuma em reatores UASB: uma abordagem sustentável

Abstract

The Upflow Anaerobic Sludge Blanket (UASB) used by the Municipal Department of Water and Sewage (DMAE) is an anaerobic treatment system that operates with an upward gravity flow, where the effluent passes through a sludge blanket, promoting the decomposition of organic matter by anaerobic bacteria. However, foam accumulation on the reactor walls impairs process efficiency. This study aimed to produce a biosurfactant (BS) from the yeast Rhodotorula mucilaginosa and apply it for the bioremediation of foam accumulated in UASB reactors, providing a sustainable solution to this problem. The inoculum analysis showed sufficient dissolved oxygen (DO) on the first day to proceed with experiments, ensuring faster and more sustainable processing. The BS demonstrated droplet collapse and spreading, confirming its surfactant properties, with a yield of 10.66 g/L. The produced BS had a critical micelle dilution (CMD) of 60 g/L and a critical micelle concentration (CMC) of 5 g/L, indicating low micelle-forming efficiency. The emulsification index (EI) was considered good (≥50), showing efficiency in stabilizing emulsions. Stability tests indicated that pH 6.6 and 30 °C were the most favorable conditions. Foam was collected directly from the UASB reactor and analyzed for composition. Applying the BS to the foam showed the best results on the first day under condition C3 (medium + foam + BS + yeast). In optimized conditions, samples containing BS (C4) and BS combined with hydrogen peroxide (C5) significantly reduced total solids (TS), indicating effective foam degradation. Additionally, efficient recovery of acetone used in fermentation contributed to overall sustainability by reducing costs and environmental impacts. Although the results are promising regarding efficiency and sustainability, further experiments are needed to confirm the applicability of the BS in treating foam in UASB reactors.