Antagonistic Effects on the Methane Yield of Liquid Hot-Water Pretreated Press Mud Fractions Co-digested with Vinasse

Sugar cane press mud pretreated by liquid hot water was separated into a liquid fraction and a solid fraction. These fractions were blended with vinasse in different proportions, according to a three-factor mixture design, to evaluate their synergetic and antagonistic effects on the methane yield. The biochemical methane potential was determined in batch assays under mesophilic conditions (37 ± 1 °C). The highest methane production rates were obtained for a mixture of 33% chemical oxygen demand (COD) vinasse and 67% COD liquid fraction of press mud and for sheer vinasse (73 and 84 N mL CH 4 g –1 COD fed day –1 ). The maximum methane yield was found for the pure liquid fraction with a value of 369 N mL CH 4 g –1 COD fed . For most mixtures examined, antagonistic effects were found, with significant differences when mixing vinasse and the liquid fraction.