Anaerobic digestion of stillage from a pilot scale wood‐to‐ethanol process II. Laboratory‐scale digestion studies

Abstract

The anaerobic digestion of stillage from a pilot‐scale wood‐to‐ethanol process was investigated using an 8‐litre, continuously‐fed reactor. A methanogenic consortium acclimated to Pinus radiata stillage was developed over 160 days by maintaining a low organic loading rate. The loading rate was then gradually increased to c. 4 kg COD m‐3 day‐1. Nutrient, alkalinity, and mineral requirements were quantified. Approximately 90% COD removal was obtained at specific COD utilisation rates up to 0.5 g COD g VSS ^‐1 day‐1. The methane and true cell yields, per gram of soluble COD removed, were 0.313 1 CH₄(STP) and 0.142 g VSS. The endogenous decay coefficient was 0.0083 day^‐1.