Benefit of sodium hydroxide pretreatment of ensiled sorghum forage on the anaerobic reactor stability and methane production

Abstract

The assessment of the pretreatment effect on the anaerobic digestion process is generally based on the results of batch tests, which may fail in truly predicting full-scale anaerobic reactors performance. Therefore, in this study, the effect of alkaline pretreatment on the anaerobic digestion of ensiled sorghum forage was evaluated by comparing the results of two semi-continuous CSTR (Continuously Stirred Tank Reactor) anaerobic reactors. Results showed that an alkaline pretreatment step, prior to the anaerobic digestion of ensiled sorghum forage, can have a beneficial effect both in enhancing methane production (an increase of 25% on methane production was observed, if compared to that of untreated sorghum) and in giving more stability to the anaerobic digestion process.

Keywords: Alkaline pretreatment; Alkalinity; Anaerobic digestion; Biogas; Lignocellulosic biomass.