- Biological Processes Laboratory (LPB), São Carlos School of Engineering (EESC), University of São Paulo (USP), Av. João Dagnone, 1100, Santa Angelina, São Carlos, São Paulo, 13563-120, Brazil (mdamianovic@sc.usp.br)
Anaerobic digestion (AD) offers a sustainable solution for managing sugarcane vinasse, producing renewable energy and nutrient-rich effluents. However, the seasonal availability of vinasse (7–8 months annually) causes operational interruptions during the sugarcane off-season, undermining the stability and energy output of AD systems. This study addresses these limitations by evaluating glycerol as an alternative substrate during the sugarcane off-season in an anaerobic structured bed reactor (AnSTBR). The reactor was operated for 370 days at 30°C with polyurethane foam as support material. The system was inoculated with UASB granular sludge and transitioned between four operating stages: vinasse mono-digestion (V-moD), vinasse-glycerol co-digestion (VG-coD), glycerol mono-digestion (G-moD) and vinasse mono-digestion (V-moD), respectively. During Stage I, vinasse AmoD achieved 81.1 ± 1.5% COD removal at the highest organic loading rate (OLR) of 5.0 kg-COD m⁻3 d⁻1, with volumetric methane production (VMP) of 1027 NmL-CH4 L⁻1 d⁻1 and a methane yield (MY) of 250.6 ± 13.2 NmL-CH4 g⁻1-CODrem. Supplementing glycerol up to 50% (in terms of mass COD) in Stage II increased COD removal to 84.7 ± 1.1% and VMP to 1106.9 ± 70.2 NmL-CH4 L⁻1 d⁻1, though methane content declined by 5%. Glycerol AmoD (Stage III) yielded stable COD removal (93.1 ± 0.6%) and VMP (1075.1 ± 95.0 NmL-CH4 L⁻1 d⁻1), despite partial alkalinity reductions (881 to 253 mg-CaCO3 L⁻1) linked to higher metabolite accumulation (20 to 277 mg L⁻1). Returning to vinasse AmoD restored COD removal to 82.3 ± 0.6% with enhanced methane content (69.6 ± 0.6%) due to increased homoacetogenic activity. Substrate switching showed no significant impact (α = 0.05) on vinasse MY. Microbial analysis revealed shifts from Clostridium dominance during glycerol use to Bacteroides and Porphyromonas during vinasse digestion. Methanosaeta (47.6–74.2%) and Methanolinea (11.1–30.5%) dominated acetoclastic and hydrogenotrophic methanogenesis, respectively, supporting balanced acidogenesis-methanogenesis through acetogen-methanogen syntrophy
How to cite: Damianovic, M. H. R. Z., Takeda, P. Y., and Borges, A. D. V.: Glycerol Supplementation for Seasonal Stability in Anaerobic Digestion of Sugarcane Vinasse: Performance and Microbial Shifts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13931, https://doi.org/10.5194/egusphere-egu25-13931, 2025.
