Reaction kinetics modeling for dry anaerobic digestion of lignocellulosic Hura crepitans leaves

In this study the impact of feedstock-to-inoculum (F/I) ratio in dry anaerobic digestion (DAD) of Hura crepitans leaves was evaluated. Measured biogas volumes, as well as the chemical kinetic predictions for exponential, logistic and Gompertz model, depicting the agreement of the simulations over time, were also determined. The digesters were codenamed DAD2, DAD4 and DAD6 based on their F/I ratios 2, 4 and 6 at 22% total solids. Digester DAD4 was the most promising in terms of biogas production with daily biogas production of 235 ml while the cumulative biogas production was 2200 ml. On the other hand, digester DAD6 with the F/I ratio 6 recorded the lowest cumulative biogas production of 615 ml. Early commencement of biogas production in all the digesters was indicative of a good start-up phase, which is one of the challenges often encountered in DAD process. Furthermore, kinetic studies revealed a direct correlation between biodegradability constants and biogas production. The kinetic models studied revealed that logistic and Gompertz models performed better than the exponential model.

Automated summary

In this study, the impact of feedstock-to-inoculum ratio in dry anaerobic digestion of Hura crepitans leaves was evaluated. The best F/I ratio and biogas production of the digesters were determined. It was found that early start-up and biodegradability constants were positively correlated with biogas production. Logistic and Gompertz models performed better in the kinetic analysis.