Food-to-Microorganism Ratio as a Crucial Parameter to Optimize Methane Production from Sugarcane Vinasse

Determining the biochemical methane potential (<i>BMP</i>) is a key part of the anaerobic digestion research, as well as the application of the process on a full scale. Optimization of the experimental <i>BMP</i> of this substrate through the food-to-microorganism ratio is a key issue to avoid its underestimation. However, the standardized food-to-microorganism ratio used for BMP tests does not rigorously reflect the impact of the compositional variability of vinasse on the achievable methane production. The objective of this study was to optimize the <i>BMP</i> of a mixed origin sugarcane vinasse (juice and molasses) by evaluating different food-microorganism ratios. Through a multifactorial experimental design methodology (Complete Factorial Design and Central Composite Rotational Design), the <i>BMP</i> of the vinasse was maximized by increasing the food-to-microorganism ratio. A conversion efficiency to methane was achieved at 95± 2.55% compared to the theoretical BMP, with a food-to-microorganism ratio between 1.34 and 1.42 gSCOD·g^-1 VSS.