Evaluation of Biogas Production and Composition Including Trace Gases from Local Feedstocks - A Case of Kersa District, Jimma Zone, Ethiopia

Abstract

This study examines the impact of substrate type and retention duration on the anaerobic digestion yields of biogas and methane produced, as well as the emission reduction of carbon dioxide and trace gases from cattle manure, poultry litter, and their mix. A series of experiments were conducted utilizing three feedstocks—100% cattle manure, 100% poultry litter, and a 50:50 mix—were used in anaerobic digestion tests in two reactors, a 100-liter slurry for poultry litter slurry,  50:50 mix (cattle manure +poultry litter), and 450 liter slurry for cattle manure slurry, adjusted to the reactors, poultry litter produced the highest total yield (0.71835mL/g VS) and average daily output (0.3991 mL/g VS). These findings suggest that optimizing the feedstock ratio could enhance biogas generation efficiency, particularly in rural settings, while simultaneously addressing issues caused by trace gases such as hydrogen sulfide and carbon monoxide that inhibit methane production. Future research endeavors should focus on refining the other feedstock combinations to maximize biogas potential. The Modified Gompertz model demonstrated superior fitting of biogas production data relative to first-order kinetics.