Harnessing the Energy Potential and Value-Added Products from the Treatment of Sugarcane Vinasse: Maximizing Methane Production Through Co-Digestion with Sugarcane Molasses and Enhanced Organic Loading.

This study assessed the impact of organic loading rate (OLR) on methane (CH) production in the anaerobic co-digestion (AcoD) of sugarcane vinasse and molasses (SVM) (1:1 ratio) within a thermophilic fluidized bed reactor (AFBR). The OLR ranged from 5 to 27.5 kg COD.m.d, with a fixed hydraulic retention time (HRT) of 24 h. Organic matter removal varied from 56 to 84%, peaking at an OLR of 5 kg COD.m.d. Maximum CH yield (MY) (272.6 mL CH.gCOD) occurred at an OLR of 7.5 kg COD.m.d, while the highest CH production rate (MPR) (4.0 L CH.L.d) and energy potential (E.P.) (250.5 kJ.d) were observed at an OLR of 20 kg COD.m.d. The AFBR exhibited stability across all OLR. At 22.5 kg COD.m.d, a decrease in MY indicated methanogenesis imbalance and inhibitory organic compound accumulation. OLR influenced microbial populations, with Firmicutes and Thermotogota constituting 43.9% at 7.5 kg COD.m.d, and Firmicutes dominating (52.7%) at 27.5 kg COD.m.d. Methanosarcina (38.9%) and hydrogenotrophic Methanothermobacter (37.6%) were the prevalent archaea at 7.5 kg COD.m.d and 27.5 kg COD.m.d, respectively. Therefore, this study demonstrates that the organic loading rate significantly influences the efficiency of methane production and the stability of microbial communities during the anaerobic co-digestion of sugarcane vinasse and molasses, indicating that optimized conditions can maximize energy yield and maintain methanogenic balance.