Biogas Production from Mono / Co-digestion of Chicken droppings with Ipomoea perfurea Grass

Abstract

The depletion of fossil fuel reserves, energy crisis, industrialization, rapid growth in population and environmental issues across the globe have aroused interest and attention to be shifted to biofuels (biogas) production. This research work focused on biogas production by mono / co-digestion of Chicken droppings with Ipomoea perfurea grass. Simplex Centroid Design (S.C.D) was employed for designing the experiment in-terms of mixing ratios using Minitab Software version 17. The proximate compositions of fresh formulated substrates prior to digestion for mono and co-substrates A (100%: Ipomoea perfurea), B (100%: Chicken droppings) and A+B (50%: Ipomoea perfurea & 50%: Chicken droppings) were determined with respect to their potentialities in terms of volatility content as 47.10, 52.60 and 55.80%, while 18.10, 16.01 and 14.20% for moisture content, 29.26, 26.08 and 24.04% for carbon content respectively. The biogas production was carried-out at mesophilic temperature ranging from 26^oC to 31^oC for residential period of 42days. The production began on the first day and reached peak on the 4^th and 5^th day but declined on the 40th and 42nd day before termination. The least and optimum yield for dried substrates were 334g/kg for mono substrates (B) and 357g/kg for co-substrates (A+B), while 410g/kg for fresh mono-substrate A and 430.5g/kg for co-substrate A+B respectively. The methane flammability test confirmed that the biogas was combustible and a pale bluish flame that burnt for 1 minute 45 seconds without soot was confirmed, and the ANOVA results revealed a statistical significance difference between fresh and dried substrates at P ≤ 0.05 confidence level. The least and optimum C/N ratio for dried mono and fresh co-digested substrates were 14:1 and 21:1accordingly. Based on this research study, the fresh co-digested substrates produce a better yield than dried mono / co-digested substrates in the production of biogas for cooking. Purification of biogas mostly depends on end usage, therefore, scrubbing needs to be carried out to improve methane yield and reduce impurities to the minimum level to suit the application of interest.

Keywords: Biogas, Mono-digestion, Co-digestion, Mesophilic temperature, Substrate.