Use of anaerobic co-digestion as an alternative to add value to sugarcane biorefinery wastes

Abstract

In this study the anaerobic co-digestion (AcD) of sugarcane biorefinery by-products, i.e. hemicelluloses hydrolysate (HH) (obtained by hydrothermal pretreatment of sugarcane bagasse), vinasse, yeast extract (YE) and sugarcane bagasse fly ashes (SBFA), was optimized by means of biochemical methane potential experiments. The best experimental conditions of AcD (25-75% HH-to-vinasse mixture ratio; 1.0 g L^-1 YE; 15 g L^-1 SBFA and 100-0% HH-to-Vinasse; 1.5 g L^-1 YE; 45 g L^-1 SBFA) led to the production of 0.279 and 0.267 Nm³ of CH₄ per kg of chemical oxygen demand (COD) with an energy surplus of 0.43 and 0.34 MJ kg SB^-1, respectively. Adsorption experiments using SBFA were carried out and showed this residue could adsorb up to 61.71 and 17.32 mg g^-1 of 5-hydroxymethyl-2-furfuraldehyde and 2-furfuraldehyde, thereby reducing toxicity and improving biogas production.

Keywords: Anaerobic co-digestion; Biogas; Hemicelluloses hydrolysate; Sugarcane bagasse fly ash; Sustainable biorefinery; Vinasse.