Silage as a pre-treatment of orange bagasse waste to increase the potential for methane generation

Abstract

Among the various methods of pre-treatment of lignocellulosic waste with the objective of optimizing the production of methane, silage stands out as a promising alternative due to its operational simplicity, low cost and effective results. In this work, the silage of orange waste (Citrus cinensis) with 14 and 21 days and its influence on the potential of methane generation was evaluated, also evaluating the impacts of silage on the kinetics of the process. Among several configurations of substrate and inoculum studied, the best configuration observed was using the ensiled residue with 21 days and granular anaerobic sludge (ENS21 + GS), reaching a methane generation potential of about 171 N mL·g−1 VS, increasing by 119% in terms of methane generation potential without silage pre-treatment (WENS+GS), obtaining biogas with 70% in CH4. In relation to the kinetics, the silage process drastically interfered in the kinetic behavior of the methane production, being the Cone model the one that obtained the best adjustments, among those studied, for the orange bagasse residue in the evaluated experimental conditions. Silage is an attractive alternative to increase the production of methane for lignocellulosic waste, as a pre-treatment, without significantly increasing operating costs, and it can also be associated with other sequential processes to take advantage of the maximum energy potential of lignocellulosic waste.