Evaluation of the Specific Growth Rate to Predict the Biogas Production Process in a Mini-Biodigester

In this work, we are interested in the mathematical analysis of the model of a bioreactor based on the results of a model already implemented in ADM1. The study is based on the expectations of Burkinabè households with biodigesters of 4m3, 6 m3, 8 m3 or more in terms of biogas production capacity. It is an observability analysis and estimation scheme for specific growth rates for an anaerobic digestion (AD) process of cow dung. A 1- stage model of 3 dynamic states is assumed describing all anaerobic digestion with a different population of microorganisms, and the evaluation of biogas production (methane + carbon dioxide). The result of specific growth rates (µmax = 0.44d-1) of bacterial populations' concentration (24gL-1 ± 2.3%) and substrate concentration (6.5gL-1± 0.5%) are estimated from the dilution rate and biogas. Thus, biogas production ranges from 0 to 3.5 m3 per day, more than sufficient for three daily meals for a 4-person household. Overall, the dynamics of anaerobic digestion appear to depend on the type of organic matter contained in cow substrates.