Evaluation of biogas performance of saturated and unsaturated fatty acids content

Abstract. The purpose of this study was to examine the effect of saturated and unsaturated fatty acids content on the performance of biogas production and examined the characteristics of the anaerobic digestion. Experiments were performed using biogas potential tests at a substrate loading of 5g VS/L and feed to microorganism ratio (F/M) of 1.0 under the mesophilic condition. The biogas production patterns, lag phase, and times taken for 90% biogas production (T90) were used for the evaluation of the biogas production with biochemical methane potential(BMP) test. The cumulative biogas yield of the mixed agricultural by-products(ABPs) by most unsaturated fatty acids was higher than most saturated fatty acids. As the content of unsaturated fatty acids increased, the initial compliance time and T90 increased and the biogas production rate slowed down. The biogas production pattern of mixed ABPs by most unsaturated fatty acids was shown two-step lag phase, while mixed ABPs by most saturated fatty acids was shown one-step lag-phase. The trend of two-step lag phase might come from the effect of large numbers of double bonds between the carbon atoms of fatty acids in ABPs.