Comparative Anaerobic Digestion of Corn Stover, Chicken Droppings and Their Co-Digestion for Biogas Production

Abstract

Research interest in developing alternative energy sources, such as biogas generation, has been stimulated by the high cost of renewable energy technologies in Nigeria and concerns about the depletion of fossil fuels and the associated ecological consequences. Biogas contains methane, which can be used as a clean energy source. It is produced from the treatment of organic wastes, such as agricultural waste, manure, kitchen waste and sewage, through anaerobic digestion. This process reduces waste and supports economic sustainability. This study compared biogas production from corn stover and chicken droppings. The biogas experiment was carried out in three different 100-L anaerobic digesters, A, B and C, which contained corn stover, chicken droppings and a blend of chicken droppings and corn stover, respectively. These were incubated for 30, 45 and 30 days, respectively, for digesters A, B and C at ambient mesophilic temperatures (21oC to 32oC), reflecting differences in the substrates' characteristics and biodegradability. Methane gas production was monitored and collected for 10 days from the first day of methane production in all bioreactors (19th, 36th and 21st days for digesters A, B and C, respectively). A portable biogas analyser (Model AZ77535) was used to determine the composition of the biogas produced. The biogas production potentials obtained from digesters A, B and C were 80.013 L, 129.011 L and 88.014 L, respectively, while the methane compositions were 89%, 81% and 90%, respectively. An increase in cumulative production rate was recorded for all the substrates. The analysis showed that digester B had the highest biogas production potential, while digester C had the highest methane composition. This indicated the suitability of these substrates for biomethane production.