Pretreatment of digested manure fibers at high temperature (185°C) with lime added enhances methane production

Abstract

The anaerobic digestion of manure is facing the challenge of limited degradation because of recalcitrant nature of the fibers. In this study different concentrations (1–3%) of lime (CaO) pretreatment for AD of digested manure fibers under thermophilic conditions was evaluated. The results of the study revealed that there was 30.6, 36.4 and 23.5% reduction in cellulose, hemicellulose and lignin fraction of manure fibers during pretreatment when subjected to 3% CaO pretreatment. Degradation of manure fibers also improved because of pretreatment and 40.6% of volatile solids were degraded during AD process. Methane yield was improved by 115.7% in course of this study. Additionally, carbohydrates were main fraction used by anaerobic bacteria to produce methane and 74.9% cellulose and 79.3% hemicellulose was converted to methane in sample which was pretreated using 3% CaO at 185 °C for 30 min.