Effects of co-digesting swine manure with chicken Manure on biogas production

Abstract

Swine manure (SM) was co-digested with chicken manure (CM) with a view to optimizing biogas production. Five mixtures of SM and CM at ratios of SM/CM 0:1 (CM only), 3:7, 1:1, 7:3 and 1:0 (SM only) (w/w dry basis) were digested in batch-type anaerobic digesters for 63 days. The results showed that co-digestion had significant (p ≤ 0.05) effect on the substrate temperature, pH and biogas production. The mean substrate temperature and  pH during digestion were 28.5 ± 2.5^o C and 6.80 ± 0.55, respectively. Biogas production from mixture ratios    (MRs) 3:7, 1:1, 7:3 and 1:0 stopped on the 32^nd, 61^st , 35 ^th and 33^rd day, respectively, suggesting completion or  inhibition of the digestion process. The individual manures, MRs 0:1 and 1:0 produced 0.52 and 0.38 L kg^-1 VS  fed day^-1 , respectively. MR 3:7 produced 61.5% and 47.4% lower than MRs 0:1 and 1:0, respectively. MR 1:1 produced 69.2% and 131.6% higher than MRs 0:1 and 1:0, respectively. MR 7:3 produced 21.2% lower than MR 0:1 and 7.89% higher than MR 1:0. It can be inferred from the results that anaerobic digestion of mixture of SM and CM at ratio 1:1 (w/w dry basis) appeared to be the optimum for improving biogas production.

Keywords: Co-digestion, Biogas, Swine manure, Chicken manure, Mixture ratio