Co-fermentation of oil palm lignocellulosic residue with pig manure in anaerobic leach bed reactor for fatty acid production
Abstract Batch experiments were performed to investigate the co-fermentation of palm oil empty fruit bunch (EFB) and pig manure (PM) at various PM mixing ratios (% PM ) and flushing intervals ( FI ) over 60-day fermentation time ( FT ) using anaerobic leach bed reactors. Addition of PM promoted hydrolysis yield ( η h ) and acidification yield ( η a ) due to the more degradable and soluble nature of PM that gave out organic acids, and nutrients it supplemented. The highest η h and η a found were 27.9 ± 0.3% and 51.7 ± 2.6%, respectively. Longer FI that delayed bed flushing prolonged the dry condition where hydrolytic reaction could be enhanced. The developed multiple regression model with R 2  = 0.87 and p FI and higher pig manure mixing ratios. The mixing of an easier biodegradable pig manure as co-substrate could help induce higher degree of fermentation of the recalcitrant EFB.