Cultivating conditions optimization of the anaerobic digestion of corn ethanol distillery residuals using response surface methodology~+

摘要

This study investigated the individual and interactive effects of three factors - temperature, inoculum/substrate ratio (ISR) and inoculum typology - on the anaerobic digestion of corn ethanol distillery wastewater. Biochemical methane potential assays planned with factorial design with two independent quantitative variables on three levels (ISR: 1:1, 2:1 and 3:1; temperature: 30°C, 33.5°C, 37°C) and one independent qualitative variable (inoculum type: suspended, granular, mixed) have been performed. Response Surface Methodology has been used to study the effect of the factors with the aim of maximizing the specific methane yields (Y_(CH4)) obtainable with this substrate. The results show that all three investigated factors influence in a significant matter the Y_(CH4), the ISR having the strongest effect on it. The temperature has significant influence on the Y_(CH4) only in combination with high ISR values. The optimal conditions for the maximum Y_(CH4) (551 mL CH4 g~(-1) VS_(added)) have been found at 37°C operating temperature, ISR=3:1 and using granular inoculum. These conditions gave rise to a 4-fold increase of Y_(CH4) with respect to the worst combination of factors (Y_(CH4)=129 mL g~(-1) VSadded for the suspended inoculum type, at 30℃ and ISR=1:1). The results improve the knowledge on the digestion of this substrate, providing information for successful process up-scaling.