Trace elements effect on hydrolytic stage towards biogas production of model lignocellulosic substrates.

Abstract The effect and the response of several trace elements (TE) addition to the anaerobic degradation of key compounds of lignocellulosic biomass were evaluated. Lignin, cellulose and xylose were selected as principal compounds of lignocellulosic biomass. Lignin degradation was only improved by the addition of 1000 mg Fe/L, which allowed an improvement on the methane yield coefficient of 28% compared to control. SEM images from an abiotic assay showed that this effect is more likely related with a chemical effect induced by the Fe solution, instead of an enzymatic response. Pre-treatments focused on breaking the recalcitrant structure of the lignin could be more promising than TE addition for rich lignin-content substrates. Unlike to the response observed with lignin, cellulose showed a clear effect of the TE addition on methane production rate, indicating a higher preponderance of the enzymatic activity compared to the lignin biomethanization. Experiments with xylose resulted in a strong accumulation of volatile fatty acids. TE addition should be adapted to the substrate composition given the different response of each lignocellulosic compound to the different TE addition. Highlights • Lignin, cellulose and xylose were selected to represent the lignocellulose biomass. • Trace elements addition affected differently the biomethanization of each compound. • The addition of 1000 mg Fe/L had an abiotic effect on the structure of the lignin. • Biomethanization of cellulose was significantly affected by Mn addition. [ABSTRACT FROM AUTHOR]