Utilization of Papaya seed in anaerobic co-digestion with dairy cow manure on the bio-digester performance

Abstract

This study examined utilization of papaya seed (PS) and the effect of pre-treatment in the form germination of PS and used it as a co-substrate with dairy cow manure (DCM) on the biogas digester performance. There were three digesters, namely, R1 (100% DCM), R2 (95% DCM and 5% non-germinated meal of PS), and R3 (95% DCM and 5% germinated meal of PS), which were run for three hydraulic retention times. The presence of PS as co-substrates of DCM can increase (p<0.05) methane production (L/kg substrate) by 195.01% at R2 and 211.08% at R3 compared to that in R1, and R3 resulted in 5.45% more methane production than that in R2. This enhancement was a significant increase in the biogas industry. Total ammonia nitrogen concentrations, pH values were close to the neutral levels, and the concentrations of volatile fatty acids were not significantly different (p>0.05) so that the digester conditions were optimum for the anaerobic digestion process. Therefore, germinated and non-germinated PS can be used as co-substrates with DCM to increase the methane yield, and germination can be considered as a method that can increase the methane yield of PS.