Food-to-microorganism ratio as a crucial parameter to maximize biochemical methane potential from sugarcane vinasse

Determining the biochemical methane potential (BMP) is an important step in the study of anaerobic digestion of sugarcane vinasse before the implementation of a full scale bioreactor. However, the compositional analysis and the evaluation of different food-to-microorganism ratio to avoid underestimating the BMP of vinasse have not been extensively used in BMP assays. Consequently, the study of the literature revealed differences between vinasse BMPs where the food-microorganism ratio used was the standardized, probably because this factor does not reflect the impact of the vinasse compositional variability on its BMP. Thus, the present research aimed to optimize the food-microorganism ratio to maximize the BMP of a mixed origin vinasse and compare it with the literature. Through a multifactorial experimental design associated with the Response Surface Methodology, the BMP of the vinasse was maximized by increasing the food-to-microorganism ratio. The most significative factor in this study was the increase of vinasse concentration in the BMP test. A conversion efficiency to methane achieved was 95 ± 2.55% compared to the theoretical BMP, with a food-to-microorganism ratio between 1.34 and 1.42 gSCOD·g −1 VSS. Therefore, the results of this investigation demonstrated that the BMP of vinasse can be maximized by optimizing the food-microorganism ratio. It is not recommended to standardize this parameter for sugarcane vinasse due to its high compositional variability. Graphical abstract